Lawrence M. White University of Toronto, Canada. lawrence ...kcr2019/down/abs/SS/KCR 2019... ·...

372 KCR 2019

Musculoskeletal Sep 20, Fri

SF 11 MS-01 Imaging of knee: from fundamentals to advanced concepts 14:00 - 14:30 Grand Ballroom 105

Chairperson(s): Ik Yang Hallym University Kangnam Sacred Heart Hospital, Korea Young-Hwan Lee Daegu Catholic University Medical Center, Korea

Anatomy and injuries of the cruciates: beyond the basics

Lawrence M. WhiteUniversity of Toronto, Canada. [email protected]

Anterior cruciate ligament

Two functional bundle groups- terminology relative to tibial insertion

• Anteromedial (AM) and Posterolateral (PL) bundles - stability full range knee motion

MR imaging knee extension • AM bundle slightly lax, and PL bundle tight

ACL most commonly totally disrupted ligament knee • Consequences - Instability; Osteoarthritis

MR Imaging features ACL Tearing - nonvisualization, focal disruption of ligamentSecondary signs (impact, instability) - bone “bruising”/contusion, translational malalignment

Avulsion fractures tibial footplate~ 5%• Pediatric / Adolescent population• Often associated with - tensile, partial intrasubstance

ligament injuryLarge fragment vs subtle cortical avulsions

Significance; primary fixation vs. reconstruction

Partial ACL tears - represent up to 10-43% ACL injuries • Diagnosis difficult - overlap: complete tear,

myxoid changes Significance - functional instability “high-grade” partial tears

• Acutely or over time

Isolated tears AM or PL bundles ACL, < 5% of partial injuries

• Rare: Partial tears usually involve both bundles• MR Imaging: difficult accurately isolate partial injury

to AM or PL bands Setting - single bundle tear • ‘Single bundle augmentation’ surgical reconstruction

torn bundle, preservation intact bundle fibers

Posterior cruciate ligament

Two functional bundle groups - terminology relative to femoral origin PCL

• Anterolateral (AL) and Posteromedial (PM) bundlesPCL injury 2-40% of all knee injuries (10-20x less common than ACL tears)

• Isolated in only 30% • Other ligamentous Injury; ACL, Posterior lateral

corner, Posterior medial corner• Multi-ligamentous injuries - associated dislocation

(neurovascular status) Mechanism PCL Injury - tensile stretching deformation

• Direct blow to anterior t ibia on flexed knee (classically mid-distal tearing PCL)

• Hyperextension (classically proximal tearing PCL) MR Imaging features PCL Tearing - nonvisualization, discontinuity

• amorphous high T2 signal, avulsion injuries

Avulsion Injuries PCL - Femoral origin or Tibial insertion • Tibia - osseous fracture tibial footplate • Femur - periosteal stripping +/- osseous fragment

Surgical treatment (acute)- reduction/fixation

Acute versus Chronic PCL injury - MR imagingAcute injury - high clinical utility MRI evaluation - degree ligament disruptionChronic PCL injury * reliance clinical exam

• MR findings; limited value function ≠ integrity PCL (chronic injury) MRI

• Intrinsic healing capacity PCL - residual laxityTreatment PCL tears controversial- traditionally isolated injuries treated nonoperativelySurgical reconstruction - populari ty increasing understanding PCL instability and association with osteoarthritis

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Summary

Patterns injury and biomechanical failureUnique importance imaging features vs. clinical examInsight of which - important

• Clinical management• Evolving surgical techniques: - recapitulate

anatomy + function ligament bundles - restoration joint stability

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Imaging around the corners: MRI evaluation of the postero-medial and postero-lateral corners of the knee

Lawrence M. WhiteUniversity of Toronto, Canada. [email protected]

Multi-ligamentous injuries - Knee Joint • Diagnostic and therapeutic challenge• Often overlooked, difficult Dx at clinical exam

Accurate recognition & diagnosis - often by imaging • Critical - treatment, outcome; stability and prognosis

Posterolateral Corner -PLC complex InjuriesMR imagingReliably visualize; FCL, Popliteus tendon, Popliteofibular ligament (93-100%)Variable/Inconsistent visualization; Arcuate ligament: 24-100%, Fabellofibular ligament: 51-72 %

FCL - Most commonly injured. Usually torn middle 1/3 or fibular insertionPFL, Arcuate, FFL - Injuries can be difficult to detect MRI (especially chronically)

• Uncommon in absence other injury to critical stabilizers * edema adjacent to popliteus tendon

Mechanism - Posterolateral Corner InjuryBlow antero-medial knee; hyperextension, valgus/flexed knee, ++ external rotation tibia

Isolated injury rare (15-27%) - Frequently associated with ACL or multi-ligamentous injuries

Acu te - assoc ia ted ex t ra -a r t i cu la r in ju r ies (neurovascular injury)Chronic - varus + rotational (postero-lateral) instability

• Functional disability, degenerative osteoarthritis• Increased stress ACL/PCL reconstruction grafts

Treatment - Dependent upon timing of presentation

Posteromedial Corner - KneeAnatomically extends from posterior margin of MCL to medial margin PCLSynergistic Unit

• Semimembranosus• Meniscus + Meniscotibial ligament• Posterior Oblique Ligament

Posterior Oblique Ligament - Anatomically and functionally distinct from MCLImportant restraint - injured 90% cases of antero-medial rotational instability (AMRI)

Mechanism of injury - Posteromedial CornerValgus stress and internal rotation (± hyperextension)PMC injury isolated in only 12% (associated ACL injury in 78% of cases)

MCL- Primary medial stabilizer against valgus stress - most commonly injured knee ligament

Important to distinguish Isolated MCL vs. MCL + PMC (Post Oblique Lig) injuryImplications MCL + Posteromedial corner (POL) injury +/- ACL

AMRI - rotational instability/subluxation jointFunctional instability, weakness, ACL dysfunction, Osteoarthritis

Unrecognized PMC injury combined with ACL tear/reconstruction

• account for variable postoperative outcome: graft failure, osteoarthritis - after ACL reconstruction

Take Home Points: Posteromedial and Posterolateral Corner Injuries KneePLC - FCL, Popliteus, Popliteo-fibular ligamentsPMC - Posterior Oblique Ligament*, (Semimembranosis, Medial Meniscus)

Rarely isolated injuriesDiagnosis can be challenging + injuries can be overlooked. Imaging critical to managementUntreated

• Chronic rotational instability• poor outcomes following cruciate ligament

reconstruction

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Meniscal tears and postoperative menisci

Joon-Yong Jung The Catholic University of Korea, Seoul St. Mary's Hospital, Korea. [email protected]

1. Meniscus

The menisci are fibrocartilaginous structures of a dense extracellular matrix, composed of water, collagen and proteoglycan. The meniscus can be divided into three layers: a superficial layer with mesh-like fine fibrils, a lamellar layer with randomly oriented collagen fibers, and a central layer with circumferential collagen fibers, reinforced by radial collagen fibers. The major roles of the meniscus are shock absorption and axial load distribution across the knee. The concerted mechanism of the circumferential collagen bundles and strong attachment to tibia enables menisci to resist of compressive loading. Therefore, tears in meniscus proper or root are predisposing to osteoarthritis by alteration of the biomechanics and kinematics of the knee.

With the advent of ultrashort echo time (UTE) MRI, the complex collagen fibrillar network of the menisci is unmasked. Moreover, UTE- T1rho or T2 mapping provides quantitative metrics for the ultrastructural and biochemical alterations of the menisci and has a potential to be used as imaging biomarkers.

2. Meniscal degeneration and tear

Since water molecules within the tear are mostly bound component, short to intermediate TE sequences are the mainstay for diagnosis of most meniscal tears. Whereas, T2-weighted images with longer TE is preferred for root tears.

Meniscus pathologies range from intrasubstance degeneration, free edge irregularities representing fraying or fibrillation to tears. The MR diagnostic criteria for meniscal tears are contact of linear intrameniscal signal to the surface, and distortion of the normal meniscal appearance. The tear types are described by their orientation. But there has been no uniform classification system in tear types. The International

Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) classified meniscal tears into 6 types : longitudinal-vertical (extension would be a “bucket-handle tear”), horizontal, radial, vertical flap, horizontal flap, and complex.

Meniscal root tears have received increased attention in recent years due to its high association with meniscal extrusion. Meniscal ramp lesion is a meniscocapsular separation at the peripheral attachment of the posterior medial meniscus. It is a lesion associated with ACL tear in both acute and chronic setting and should be reported on MRI because of its location at arthroscopically “blind spot”, but have a favorable environment to heal with a repair.

3D FSE sequences offer isotropic submillimeter acquisition that can be used for multiplanar reformation. 3D axial images parallel to the orientation of meniscus is generated with a thin slice thickness to minimize partial volume effect and provides the overview of complex configuration of the displaced meniscal tears.

3. Postoperative meniscus

The primary goal of meniscal surgery is to restore pain-free function. In partial menisectomy, every effort is made to keep as much of the peripheral meniscal rim to preserve load transmission. Meniscal repair is generally used for red zone tear. However, with the increased effort to preserve as much meniscal substance as possible, repairs of the radial tear have become more popular. The root tears without significant cartilage abnormality are often promptly repaired because the healing is facilitated by surrounding rich synovial blood supply. Transtibial pullout technique can be performed for meniscal root tears.

The classic criteria for diagnosing meniscal tears are not suited for the re-tear of the postoperative meniscus. The irregularity in meniscal contour, a linear high-signal extending into the articular surface on several images, a

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displaced meniscus fragment, or a change in the signal intensity pattern through the meniscus compared with the baseline MRI should be considered.

The goal of meniscus allograft transplantation (MAT) is to provide load-bearing funct ion and

chondroprotective effects in younger active patients after partial menisectomy. Graft extrusion is frequent complication particularly in medial MAT. The long-term clinical implication of graft extrusion has yet to be established.

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Patellofemoral Joint

Jaehyuck YiKeimyung University School of Medicine, Korea. [email protected]

I. Anatomy

• Bone: patella (largest sesamoid bone, leverage of extension), femur trochlea

• Extensor muscles & tendon (quadriceps, patella tendon)

• Medial & lateral retinaculum• Anterior synovial tissues, joint capsule, suprapatellar

plica, infrapatellar plica• Fat pad (suprapatellar fat pad, Hoffa’s fat pad)• Bursa• Iliotibial band* Active stabilizers: extensor muscles* Passive stabilizers: bone (deep femoral sulcus, high

lateral trochlea), ligaments (retinaculum)* With full-extension & relaxation of knee, normally

about 1cm passive medial & lateral displacement of patella (25% width of patella)

II. Variant & anomaly

1. Bipartite/multiparite patella• Type 1: inferior pole (~1%), type 2: lateral margin

(20-25%), type 3: superolateral portion (~75%)2. Dorsal defect of patella

• Commonly superolateral quadrant3. Nail-Patella disease

• Hereditary osteo-onychodysplasia (HOOD) disease (autosomal dominant)

• Iliac horns (symmetric, 80%), absent/hypoplastic patella (asymmetric), overgrowth medial femoral condyle, hypoplastic lateral femoral condyle, absent/hypoplastic radial head, clubfoot deformity

III. Causes of painful patellofemoral joint

1. Patellar compression syndrome 2. Patellar instability3. Fracture/dislocation

4. Articular cartilage injury5. Osteochondritis dissecans6. Soft tissue lesions

• Plica syndrome• Fat Pad Syndrome• Iliotibial Band Friction Syndrome• Bursitis

7. Overuse Syndromes8. Complex regional pain syndrome9. Miscellaneous

• Inflammatory disorders, crystal-deposition disorders, neoplasm etc.

IV. Patellofemoral instability

• Chronic subluxation; acute dislocation; recurrent dislocation

• 3 major morphologic abnormalities predisposing patellar instability: trochlea dysplasia, patella alta (camelback sign), lateralization of tibial tuberosity

1. Patella maltracking• Movement imbalance of patella and its stabilizers

within trochlea groove , usually patella tilt (+)• Causing factors: muscular imbalance, joint

malalignment, excessive knee valgus, quadriceps contracture, joint overuse, patella alta, trochlea dysplasia, femoral torsion, joint laxity

2. Trochlea dysplasia• Type A: normal shape & shallow trochlear groove• Type B: flattened or even convex trochlea• Type C: trochlear facet asymmetry with high lateral

facet and hypoplastic medial facet• Type D: type C features with vertical link between

facets (cliff pattern)3. Imaging assessment

• Q angle (degree of valgus force on patella, 30˚ flexion): high Q angle (> 15˚), tendency for lateral instability

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• Patella height (Insall-Salvati ratio, TL/PL): normal 0.8-1.2; patella baja < 0.8; patella alta > 1.2

• Trochlea dysplasia (sulcus angle): mean angle of trochlear dysplasia > 151°

• Patella tilt (lateral patellofemoral angle): abnormal < 7˚

• Trochlea facet asymmetry (MT/LT): abnormal < 0.4• Trochlea depth: abnormal < 3 mm• Lateralization of patella: mild < 5 mm, moderate

5-10 mm, severe > 10 mm• Lateralization of tibial tuberosity (TT-TG distance):

normal < 15 mm, borderline 15-20 mm, abnormal > 20 mm

• Status of stabilizers, fat pad, cartilage & bone4. Chronic subluxation

• Extensor mechanism imbalance and some patellofemoral joint dysplasia

• Similar associated conditions to patella maltracking• Localized pain of medial aspect of patella or distal

pole5. Acute dislocation

• Usually twisting injury, in most cases, normal anatomy

• MRI: lateral subluxation of patella, impaction of medial patella & anterolateral lateral femoral condyle with/without osteochondral fragment, rupture of medial retinaculum (sometimes looks intact)

6. Recurrent dislocation• F > M (1.5:1~5:1), peak incidence during puberty• External rotation and valgus stress

V. Patella compression syndrome

• Overconstrained patella by the surrounding soft tissue → restricting patellar mobility

• May occur on one side (usually laterally) or on both sides of the patella

• Deleterious effects on the articular cartilage and degenerative arthropathy

1. Excessive lateral pressure syndrome2. Global patella pressure syndrome

VI. Fat pad syndrome

1. Suprapatella fat pad impingement• Suprapatellar fat pad: intracapsular, extrasynovial

structure, usually triangular shape• Usually due to either developmental cause or

abnormal mechanic (acute or repetitive trauma)• MR signal alteration & mass effect (convex posterior

border) of the fat pad2. Infrapatellar fat pad impingement (Hoffa disease)

• Usually single or repetitive trauma → hemorrhagic, inflamed & hypertrophied fat pad → impingement

between the tibia and femur (vicious circle)3. PTLFC (patella tendon-lateral femoral condyle)

friction syndrome • Impingement of lateral Hoffa’s fat pad between

patella and lateral femoral condyle & usually associated with patella maltracking

• Maybe patella tilt without subluxation• MRI: focal area of high T2 signal (edema) within

lateral portion of Hoffa fat pad, sometimes arthrosis of lateral PF joint, associated patella tilt or patellar subluxation, patella alta

4. Infrapatellar plica syndrome (posterior Hoffa’s fatpad impingement)• Infrapatella plica (ligamentum mucosum, 65% (+) in

cadaveric study)• Traumatic injury of infrapatellar plica, possibly

related to Hoffa’s disease• MRI: curvilinear or globular T2 high signal along

course of infrapatellar plica extending into Hoffa’s fat pad

VII. Osteochondrosis

1. Osgood-Schlatter disease• Traction apophysitis of patellar tendon insertion

on tibial tuberosity (repetitive microtrauma during phase of skeletal maturation of tibial tubercle

• Bilateral in 25-50%, adolescents (male 10-15, female 8-12 years old), M > F

• Common in jumping & kicking sports, Usually self-limited

2. Sinding-Larsen-Johansson disease• Attachment of patellar tendon on inferior pole

of patella, chronic traction injury (repetitive microtrauma) of immature osteotendinous junction

• Typically adolescent (10-14 years old)., may coexist with Osgood-Schlatter disease

• Associated with spastic paralysis (cerebral palsy)

VIII. Bursitis of anterior knee

• Prepatellar bursitis (anterior to patella): housemaid’s knee

• Superficial infrapatellar bursitis (anterior to tibial tuberosity): preacher’s knee

• In the athlete, acute hemorrhagic bursitis resulting from a direct blow

IX. Tendinopathy _ injury gout

1. Quadriceps tendon injury• More prone to traumatic tear (PT: more prone to

overuse injury)• Forced knee flexion or direct blow• Spontaneous rupture associated with predisposing

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illness (+): DM, connective tissue disorders (SLE, RA, gout), renal impairment, quinolone, steroid use

• Mostly osteotendinous junction at superior pole of patella

2. Jumper’s knee (patellar tendinosis)• Overuse injury of proximal patellar tendon (e.g.,

jumping sports), M > F

3. Patellar tendon rupture• Rare & predisposing factors (degenerative

tendinosis, previous steroid injections, previous ACL repair with patellar graft and certain chronic medical disorders)

4. Miscellaneous tendinopathy• Inflammatory tendinopathy (enthesitis), crystal

deposition disorders etc.

X. Cartilage injury

1. MR classification of chondromalacia• Grade 0: normal• Grade 1: cart i lage signal abnormal i ty, but

architecturally intact

• Grade 2: superficial fraying; erosion or focal defects of less than 50% of cartilage thickness

• Grade 3: partial-thickness defect of more than 50%, without bone edema

• Grade 4: fu l l - th ickness cart i lage loss with associated bone edema

2. Osteochondritis dissecans• 5% of knee OCD, 2nd~3rd decades, predominantly

male• Usually middle & lower third of medial facet (very

rarely lateral facet)• Arthroscopic classification

- type 1: stable lesion with a continuous but softened area covered by intact articular cartilage

- type 2: lesion with partial articular cartilage discontinuity, stable

- type 3: lesion with complete articular cartilage discontinuity, but no displacement (“dead in situ”)

- type 4: empty defect or defect with a displaced fragment or loose fragment within the bed

• MRI: T2 high signal l ine beneath the lesion indicating instability (i.e., need to operative treatment)

• DDx: dorsal defect of patella (superolateral aspect)

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Musculoskeletal Sep 21, Sat

SF 15 MS-01 Emergency & trauma 08:00 - 08:25 Grand Ballroom 103

Chairperson(s): Sang Yong Lee Soo Hospital, Korea Seon-Kwan Juhng Wonkwang University Hospital, Korea

Easily missed fractures of the upper extremity

Hyun-joo KimSoonchunhyang University Hospital Seoul, Korea. [email protected]

The role of radiologists is to diagnose more subtle easily missed injuries and to recommend the best imaging protocols. Roughly 30% of the radiographs are misinterpreted. The 2 categories of interpretations errors are: cognitive errors owing to a lack of knowledge or mistaken judgment and perceptual errors which is not seen usually (up to 80% of radiological errors). About 43~48% of the missed fractures are in upper extremity. The most common cause of the missing of the interpretation was subtlety and imperceptibility. The missed fractures are a particular problem in emergency and trauma care. The reasons of easily missed upper extremity fractures in adults are in following 3 categories: 1. Common but challenging. We know we have to look for it but they are so subtle. 2. Out of mind, out of sight. The fractures are usually out of mind because they are so uncommon. 3. Satisfaction of search. The more diagnostically challenging injuries obscure the missed fractures.

I. Common but challenging fractures

Isolated fracture of the greater tuberosity of the humerus affects younger and healthier patients compared to other humerus fractures. The major mechanism of the fractures are impaction against the acromion or superior glenoid on hyperabduction or shear or avulsion injuries associated with anterior dislocation by the rotator cuff tendons. The 59% of isolated greater tuberosity fractures are overlooked initially and they are diagnosed on MRI later (Fig. 1). External rotation AP projection image is important to evaluate the greater tuberosity humerus (Fig. 1) or true lateral view.

Radial head or neck fracture is most common fracture at the elbow joint, approximately one third of all the fractures at the elbow joint. Nearly half of the fractures at the elbow joint are nondisplaced and they may not be apparent on the initial radiographs; however, secondary signs of the fracture can be seen by visualization of the

posterior fat pad and/or elevated anterior fat pad (Fig. 2). This is an important red flag for hidden fracture in acute trauma setting. Additional view like internal and external oblique view or radial head capitellum view should be taken with this sign. MRI is a diagnostic test of choice to identify all combined injuries around elbow joint in traumatic setting.

The distal radius fracture is the most common fracture of the skeleton and account for nearly one sixth of all acute fractures. The most common mechanism is a fall on an outstretched hand. The majority of the distal radius fractures are not challenging to identify; however, nondisplaced fracture, particularly of the radial styloid are exceptional. Usually the radial styloid fractures is an oblique fracture, so they can be subtle or imperceptible.

The scaphoid is most commonly fractured bone in carpal bones and the fracture of this bone is one of the most common missed fracture (20% of the fracture is occult on routine radiographs). Up to 60 to 70 % of the fracture involve the waist of the scaphoid. Nondisplaced facture of the scaphoid can be challenging. The fracture line and cortical breakage may be subtle or absent on initial radiograph. When the patients have pain in anatomical snuff box after acute trauma, additional scaphoid view images should be obtained.

Volar plate is a fibrous structure at the volar aspect of the joint capsule of MCP and interphalangeal joints which serves to prevent hyperextension of the joint. During the process of acute hyperextension, a distal volar plate injury can result in avulsion of the adjacent bony attachment site. The injury of this volar plate more frequently occurs in younger patients and half of them are sports related. Commonly the fracture is only seen on either one view and sometime, overlapped other joints obscure the fracture. AP, lateral, and pronated oblique view should be performed when a volar plate injury is suspected clinically.

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II. Out of mind, out of sight fractures

The fracture of scapula is very uncommon (only 1% of all fractures) and is usually obscured by adjacent structures or obvious other injuries (Fig. 3). Rarity of this fracture contributes the difficulty in fracture diagnosis. Most of the scapular fractures can be detected on scapula AP and lateral image; however, only shoulder AP and lateral projection images are obtained in trauma settings. The base of the coracoid process is most commonly fractured due to avulsion. Additional axillary view or striker notch view can be helpful for detecting hidden coracoid process fracture. This type of fracture should be suspected when the patient has persistent pain after successful closed reduction from shoulder dislocation. The fracture of acromion is often associated with other shoulder injuries. Rockwood view can be a useful supplement in diagnosis. Os acromiale shouldn’t be missed as a fracture.

Carpometacarpal joint is an interlocking joint with curved and irregular articular surface, so the fracture of this joint is difficult to be evaluated radiographically. The 4th and 5th CMC joint dislocations results from less severe trauma, such as punch against to the hard surface. On AP projection image, the interruption of normally smoothly undulating and parallel articular surface is seen (disruption of parallel M). These joints is hard to be evaluated owing to overlapping structures. Further CT evaluation is needed to look for associated injuries.

The fracture in hamate occurs in dorsum, body and hook of the hamate. Except for the fracture in hook, the fractures of this bone are well visualized on routine wrist images. Carpal tunnel view or 20° supine oblique view should be additionally obtained when the patient has a persistent volar side pain. The triquetrum fracture is second most common carpal fracture and dorsal triquetrum is most commonly involved. The routine wrist images are sufficient for detection of the fractures. Most of the fractured fragments are clearly seen on the lateral view images. A 45° oblique radiograph can help to isolate the triquetrum from the adjacent bones. Most of the carpal bone fractures are treated nonsurgically. When the patients have persistent symptoms, usually removal of the fractured fragment is performed.

III. Satisfaction of search

This type of error is a common in diagnostic radiology. It occurs then the reporting radiologist fails to continue to search for other abnormalities after identifying an initial one and reports of the case is prematurely ended.

Perilunate dislocation and perilunate fracture dislocation result from a fall on an outstretched hand. Unfortunately, they are missed up to 25% of the

patients radiographically. The mechanism of this injury is a sequential process across the carpal arcs. Carpal instability occur in a stepwise manner from the radial to the ulnar aspects of the lunate. The trans-scaphoid fracture-dislocation is the most common of the carpal fracture-dislocation. Routine AP and lateral radiographs are enough to make the correct diagnosis (Fig. 4). In stage I, there is the finding of scapholunate dissociation. In stage II, there is disruption of the arc of Gilula along the lunate margins. In stage III, the lunate is completely separated from the carpal bones. The lunate is tilted volarly and partially subluxed and the other carpal bones are dorsally dislocated. In stage IV, the lunate may have pie shape on AP projection image. On lateral projection image, the lunate is dislocated volarly and other carpal bones are aligned with the radius.

Conclusion

Sometimes diagnosis of the fractures in upper extremity is challenging. The awareness of the specific injuries and an understanding of their findings will give a best opportunity to make the correct diagnosis.

References

1. Berlin L, Berlin JW. Malpractice and radiologists in Cook County, IL: trends in 20 years of litigation. AJR Am J Roentgenol 1995;165:781-788

2. Tyson S, Hatem SF. Easily missed fractures of the upper extremity. Radiol Clin North Am 2015;53:717-736, viii

3. Gyftopoulos S, Chitkara M, Bencardino JT. Misses and errors in upper extremity trauma radiographs. AJR Am J Roentgenol 2014;203:477-491

4. Itri JN, Kang HC, Krishnan S, Nathan D, Scanlon MH. Using focused missed-case conferences to reduce discrepancies in musculoskeletal studies interpreted by residents on call. AJR Am J Roentgenol 2011;197:W696-705

5. Hallas P, Ellingsen T. Errors in fracture diagnoses in the emergency department--characteristics of patients and diurnal variation. BMC Emerg Med 2006;6:4

Fig. 1. A 48 year old female patient admitted ER for

her right shoulder pain after the trauma. She had a

history of anterior dislocation of the right shoulder

and underwent successful closed reduction. On initial

right shoulder AP projection image (A), it looks like

as normal. However, there is an isolated fracture in

greater tuberosity on MRI (B). On follow up external

rotation AP projection image after 8days, more

displaced comminuted fracture is noted in greater

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tuberosity (C). External rotation view couldn’t be

obtained initially because of her shoulder pain.

Fig. 2. A 24 year old male patient admitted ER for

his left elbow joint pain after direct trauma to the

elbow joint by falling down. The anterior fat pad

is elevated on lateral projection image (A, arrows).

Nondisplaced fracture line is noted in left radial neck

on AP projection image (B, arrowhead).

Fig. 3. A 47 year old male patient admitted ER after

fall down from 5 m height. He had severe pain and

bleeding in his left elbow joint and also there was

comminuted fracture in left proximal ulna and radius.

On routine shoulder AP projection image for trauma

evaluation, there are comminuted fracture lines in

scapular spine base and medial border (arrows). The

fracture was missed initially and this fracture was

detect on chest CT later.

Fig. 4. A 24 year old male patient admitted ER after

motorcycle TA. He suffered from left wrist pain.

There is a fracture line in waist of the scaphoid (A,

arrow). Also the disruption of Gilula’s carpal arcs

is noted. On lateral projection image, the lunate is

slightly volarly tilted and has the normal articulation

with the distal radius. However, the other carpal

bones are dorsally dislocated (B, dotted circle).

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Easily missed fractures of the lower extremity

Eun Hea Park Chonbuk National University Hospital, Korea. [email protected]

In a recent study of 3081 confirmed fractures in emergency department patients

- Missed fracture: n= 115█ Subtle fractures (37%) and radiographically occult

fractures (33%).█ Lower extremity fracture: 53%Most common error alleged in medical malpractice

suits against radiologists maybe failure to diagnose, and extremity fractures are the second most frequently missed diagnosis.

Although some missed fractures may be related to perceptual errors that appear to be avoidable in retrospect, others are related to anatomic, technical, and physiologic factors that are out of the interpreting radiologist’s control.

AJR 2014; 203:492-500

1. Lower extremity fracture

1) Pelvic ring fracture2) Proximal femoral fracture: femoral head, neck,

intertrochanteric, subtrochanteric fracture3) Patella fracture4) Tibial plateau fracture5) Ankle fracture6) Midfoot and forefoot fracture

2. The pitfalls for lower extremity fractur- Insufficient views- Improperly positioned or technically imperfect

radiographs- Nondisplaced fractures- Little avulsion fractures- Satisfaction of search

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Normal and abnormal fracture healing

Wan Tae Kim Veterans Health Service Medical Center, Korea. [email protected]

Bones are organs of the skeletal system, providing shape, mechanical support, and protection to the body and facilitating the movement. Under some stressful and continuous compressive conditions, the ability of the bone tissue to tolerate strength decreases. Whenever these forces overcome the toleration of the bone tissue, bone fracture occurs.

Bone is a unique tissue and its repair process is of great biological importance, as it aims to fully restore the lamellar bone to its original condition, thereby regaining the initial bone strength. There are three main phases following a fracture in the bone repair process: 1) The early inflammatory stage, 2) The proliferative stage, and 3) The remodeling stage.

Three phases of fracture healing

Inflammatory phaseThe first phase occurring immediately following a

fracture is the formation of a hematoma in the injured bone. This hematoma is caused as a result of bleeding from the ruptured bone and the periosteal vessels that are formed within the medullary canal and beneath the periosteum. The activated coagulation system releases potent vasoactive mediators from the degranulated platelets present in the hematoma. The levels of several inflammatory mediators, including cytokines such as interleukin, and tumor necrosis factor-α (TNF-α), are significantly elevated within the first few days after the injury. During the inflammatory phase, a primitive callus develops and reduces the uncontrolled mobility at the fracture site. Under a normal condition, the inflammatory stage is fast and lasts up to a week after the fracture.

Proliferative phaseAs proliferative phase begins, necrotic bone resorption

is carried out by osteoclasts that are derived from the circulating monocytes in the blood and by monoblastic precursor cells originating from the local bone marrow.

The proliferative phase is characterized by the formation of callus and begins with continued vascular ingrowth, secretion of osteoid, and the presence of collagen fibers. This phase involves a periosteal response with angiogenesis and formation of connective tissue and soft callus, which is gradually replaced by the immature woven bone formed via intramembranous or endochondral bone formation. The osteoblasts begin to synthesize intramembranous (woven) bone tissue distal to the fracture site. Endochondral bone formation occurs in the region, which is mechanically less stable.

Remodeling phaseThe th i rd phase involves the format ion and

mineralization of the callus and replacement of the mineralized callus with mineralized bone and sculpting of the bone back to its original shape, size, and biomechanical competency via modeling and remodeling. This phase can also be referred to as secondary bone formation and involves converting the irregular woven bone callus into the lamellar bone. Adequate strength develops by 6 months and remodeling phase may occur over months to years.

Classification of fracture healing

Direct or primary fracture healingDirect healing does not commonly occur in the

natural process of fracture healing. This kind of healing involves intramembranous bone formation and direct cortical remodeling without any external tissue (callus) formation. It occurs only when rigid internal fixation anatomically reduces the mobility of the fracture fragments, thereby, reducing inter-fragmentary strain.

Indirect or secondary fracture healingIndirect bone healing is an ordered process of

bone repair and reorganization. The stages of indirect healing include impaction, inflammation, primary soft

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callus formation, callus mineralization, and callus remodeling. This type of fracture healing is generally enhanced by motion and inhibited by rigid fixation. Both intramembranous and endochondral bone healing occur in the indirect model of fracture healing.

Complications of fracture healing

Delayed unionDelayed union, by definition, is present when an

adequate period of time has elapsed since the initial injury without achieving bone union, taking into account the above variables. Inadequate reduction of a fracture, regardless of its cause, may be a prime reason for delayed union or nonunion. It usually leads to instability or poor immobilization.

Malunion

Malunion is defined as a healing of the bones in an abnormal position. Malunions can be classified as functional or nonfunctional. Malunions can occur with both axial deviations and rotational deformities.

NonunionNonunion is defined as the cessation of all reparative

processes of healing without bony union. Since all of the factors discussed under delayed union usually occur to a more severe degree in nonunion, the differentiation between delayed and nonunion is often based on radiographic criteria and time. Failure to show any progressive change in the radiographic appearance for at least 3 months after the period of time during which normal fracture union would be thought to have occurred, is evidence of nonunion.

388 KCR 2019




Imaging of muscle injuries in sports medicine

Kyung Ryeol Lee Jeju National University Hospital, Korea. [email protected]

I. Introduction

1. Muscle is an important component of the muscle-tendon-bone unit, driving skeletal motion through contractions that alter the length of the muscle.

2. Muscle-tendon-bone unit is a highly organized complex of tissues consisting of the following: (a) the muscle; (b) the myotendinous junction (MTJ), where muscle fibers interdigitate with the tendon and epimysium; (c) the tendon, which may be at the ends of and/or within the muscle; (d) the enthesis, where the tendon attaches to the bone; and (e) the bone

Fig. 1. Diagram of the muscle-tendon-bone unit.

Skeletal muscle (round circle), MTJ (arrow) and

enthesis (arrowhead) (1).

3. Muscle contraction1) Isometric contraction2) Isotonic contraction

(1) Concentric contraction(2) Eccentric contraction

II. Classification of muscle injury and cases

1. Acute trauma1) Indirect injury

(1) Muscle strain:a. Occurs during activity, typically related to

excessive stretching of a contracted muscle

during eccentric exercise while engaged in sports that emphasize speed and power, such as soccer, American football, rugby, and track and field.

b. Occurs commonly in hamstring muscle, biceps brachii, hip adductor muscles, rectus femoris muscle

c. The majority of strain injuries take place at the myotendinous junction, where muscle interdigitates with collagen, allowing force to be transferred from the muscle to the tendon

d. Three Grades based on clinical severity- Grade 1: Mild injury resulting in pain without

loss of range of motion and function, so that the athlete is able to continue activity soon after the injury

- Grade 2: Moderate injury with loss of muscle strength and range of motion

- Grade 3: Severe injury, typically related to a complete tear, with loss of function

2) Direct injury(1) Contusion:

a. An acute injury caused by a direct nonpenetrating blow to the muscle, typically affecting the anterior thigh, posterior thigh, or anterolateral upper arm

b. Injury severity is determined by the force of impact, size of the striking object, and the muscle’s state of contraction. Small objects produce more damage than a large or flat object, as the impaction force is focal rather than distributed over a broader extent of tissues,

c. Muscle damage results from compression of muscle by the striking object and compression of muscle between the object and underlying bone

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Musculoskeletal Sep 21, SatFig. 2. Contusion caused by direct impact with a

striking object (1).

(2) Hematoma: Intramuscular hematoma is easily recognized owing to local architectural distortion, appearing as an intramuscular mass of variable signal intensity depending on the stage of blood degradation. The evolution of blood degradation within intracranial hematoma at MR imaging is well described; muscle follows the same pattern, albeit with a more variable time course

(3) Laceration: Muscle laceration results from acute direct penetrating trauma by a sharp object, typically a pointed item such as a knife. Such injuries disrupt the skin, subcutaneous tissues, and fascia before piercing the muscle.

2. Subacute lesions1) Direct injury

(1) Delayed-onset muscle soreness (DOMS): Delayed-onset muscle soreness (DOMS) is a stretching injury caused by unaccustomed, prolonged, or overly vigorous eccentric exercise. The intensity, rather than the duration, of exercise is most closely related to the risk of developing DOMS. While strain injuries develop acutely during activity, patients with DOMS report gradual onset of muscle pain, stiffness, and swelling several hours or days after activity, followed by spontaneous resolution within 1-2 weeks. The etiology of DOMS is related to increases in compartment pressure and water content that disproportionately affect type 2 fast-

twitch fibers, with disruption of the Z bands of sarcomeres throughout the muscle. Diffusion tensor imaging is particularly sensitive for noninvasive identification of these microstructural alterations. Inflammation and necrosis are not consistent or dominant features

2) Indirect injury(1) Subacute hematoma

3. Chronic lesions1) Indirect injury

(1) Fibrosis/atrophy2) Direct injury

(1) Chronic hematoma(2) Myositis ossificans: Disordered satellite cell

differentiation can cause intramuscular bone proliferation, a nonneoplastic aberration of repair termed myositis ossificans. Myositis ossificans is most common after direct muscle trauma, although burns, immobilization, and neurologic dysfunction can also incite its formation. Posttraumatic ossification most commonly affects the quadriceps, adductor, or brachialis musculature of children and young adults.

(3) Muscle hernia

4. Grading systems of muscle injuryThe utility of these comprehensive systems suggest that classifications incorporating mechanism, clinical assessment, and imaging findings reflecting the precise location and extent of injury improve prognostic accuracy

5. Cases of muscle injuries in upper extremity, body, lower extremity: assessment using imaging

1) US2) MR

(1) Best imaging tool(2) Protocol advice: gradient echo MR + FS most

sensitive to subtle areas of acute interstitial hemorrhage and chronic hemosiderin

III. Conclusion

An understanding of the underlying anatomy and pathophysiology of muscle injuries helps one understand the varied imaging appearances of a range of different muscle injuries encountered in clinical practice. And MR imaging and US allow accurate diagnosis, objective assessment of injury severity, and precise localization of the sites of tissue damage, enabling detailed grading of injury severity.

References

1. Flores DV, Mejia Gomez C, Estrada-Castrillon M,

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Smitaman E, Pathria MN. MR Imaging of muscle trauma: anatomy, biomechanics, pathophysiology, and imaging appearance. Radiographics 2018;38:124-148

2. 강흥식, 홍성환, 강창호 편저. 근골격 영상의학, 제 1판. 서울:

범문에듀케이션, 2013: 323-328 3. Benca rd ino JT, Rosenbe rg ZS , B rown RR,

Hassankhani A, Lustrin ES, Beltran J. Traumatic musculotendinous injuries of the knee: diagnosis with MR imaging. Radiographics 2000;20 Spec No:S103-120

4. Lee YK, Skalski MR, White EA, Tomasian A, Phan DD, Patel DB, et al. US and MR Imaging of Pectoralis Major Injuries. Radiographics 2017;37:176-189

5. Matalon SA, Askari R, Gates JD, Patel K, Sodickson AD, Khurana B. Don't Forget the Abdominal Wall: Imaging Spectrum of Abdominal Wall Injuries after Nonpenetrating Trauma. Radiographics 2017;37:1218-1235

6. A n d r e w S o n i n e t a l . D i a g n o s t i c i m a g i n g , Musculoskeletal: Trauma 1st ed.

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SF 19 MS-01 Cartilage & bone: present and future 14:00 - 14:20 Grand Ballroom 105

Chairperson(s): Sang Hoon Lee University of Ulsan College of Medicine, Asan Medical Center, Korea Jang Gyu Cha Soonchunhyang University Hospital Bucheon, Korea

Normal cartilage structure and basic MR grading

Wook Jin Kyung Hee University Hospital at Gangdong, Korea. [email protected]

I. Normal cartilage structure

Structure and composition of articular cartilageArticular cartilage is hyaline cartilage with about 2 to 4

mm in thickness. Unlike most tissues, articular cartilage does not have blood vessels, nerves, or lymphatics. It is composed of a dense extracellular matrix (ECM) with a sparse distribution of highly specialized cells (chondrocytes). The ECM is principally composed of water, collagen, and proteoglycans, with other non-collagenous proteins and glycoproteins present in lesser amounts. Together, these components help to retain water within the ECM, which is critical to maintain its unique mechanical properties.

Along with collagen fiber ultrastructure and ECM, chondrocytes contribute to the various zones of articular cartilage-the superficial zone, the middle (transitional) zone, the deep zone, and the calcified zone. Within each zone, 3 regions can be identified-the pericellular region, the territorial region, and the interterritorial region.

The surface collagen fibrils are smaller and more closely packed than are those in the middle and deeper layers. The collagen concentration is greatest at the surface, where the small fibrils are compacted tangentially to the surface. This arrangement creased an effective pore size, which has been calculated to be about 6 nm. The largest molecule that can traverse a pore of this dimension is hemoglobin. Therefore, the surface pores readily admit most of the synovial fluid molecules. Small ions and glucose, for example, easily traverse these pores, but larger molecules such as proteins and hyaluronan (hyaluronic acid) do not enter cartilage in significant amounts under normal conditions.

Collagen fibers in the intermediate layers are no longer oriented principally tangentially to the surface but are directed obliquely or randomly. They are larger than the surface fibrils. The deepest fibrils are the largest in cartilage. They are oriented perpendicular to the joint surface. They perforate the calcified basal layers of

cartilage through the tidemark regions and eventually enter the subchondral bone layer, where they are attached firmly, similar to Sharpey’s fibers of cortical bone.

Articular (hyaline) cartilage components

1. Function1) Decreases friction and distributes loads2) Cartilage exhibits stress-shielding of the solid

matrix components due to its high water contents, the incompressibility of water, and the structural organization of the proteoglycan and collagen molecules

2. Composition1) Inclusion- extracellular matrix (water, 90% type II collagen,

proteoglycans)- cells (chondrocytes)2) % by weight- water > collagen > proteoglycan > noncollagenous

protein > cells3. Extracellular matrix

1) Watermakes up 65% to 80% of mass of the cartilage- accounts for 80% of the weight near the surface- 65% at the deep zonewater content- decreases with normal aging- increases wi th osteoar thr i t is à increased

permeability; decreased strength; creased Young Modulus of elasticity

2) Collagenmakes up 10% to 20% of total cartilage masstype II collagen accounting for 90% to 95% of the total collagen content- functions to provide cartilaginous framework and

tensile strengthSmall amounts of type V, VI, IX, X and XI collagen

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are also present3) Proteoglycansmake up 10% to 15% cartilagefunction to provide compressive strength and attract wateraggrecan is most responsible for hydrophilic behaviorproduced by chondrocytesproteoglycans composed of GAG subunits - chondroitin sulfate, keratin sulfate4) Noncollagenous protein

4. CellsChondrocytes- produce collagen, proteoglycans, and enzymes- derive from chondroblasts that are trapped in

lacunae and become chondrocytes

- chondrocyte metabol ism responds to both mechanical (mechanical load, hydrostatic pressure change) and chemical stimuli (growth factors, cytokines)

- immature articular cartilage has stem cells (mature articular cartilage does not)

II. Basic MR grading of chondromalacia on MR

- Modified Outerbridge grading- Modified Noyes grading- ICRS (the International Cartilage Research Society)

grading

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Osteochondral Injuries

Ja-Young ChoiSeoul National University Hospital, Korea. [email protected]

Osteochondral injury is a broad term used to describe an injury or abnormality of the articular cartilage and adjacent bone encompassing osteochondritis dissecans, osteochondral fracture, osteochondral defect, and osteochondral lesion. Osteochondral injuries of the major joints are important type of musculoskeletal trauma that can lead to disabling arthritis if not recognized and treated properly in the early stages. The aim of this lecture is 1) to provide an overview of

technical factors for imaging of the osteochondral injury, 2) to describe characteristic of the osteochondral injury, 3) to introduce the classifications, 4) to show typical osteochondral injuries of the knee and ankle on imaging, and 5) to present imaging findings suggesting unstable osteochondral injuries. In addition, some situations which could mimic the osteochondral injury on imaging will be illustrated.

394 KCR 2019




Bone and cartilage imaging biomarker for osteoarthritis

Hee Jin Park Kangbuk Samsung Hospital, Korea. [email protected]

Definition of biomarker

Biomarker is objectively measured and evaluated as indicators of normal biological processes, pathogenic processes or pharmacologic responses to a therapeutic intervention. Biomarker is a surrogate endpoint to substitute for a clinical endpoint (clinical endpoint -- how a patient feel, functions or survives, not objective).

Issues for biomarker for osteoarthritis (OA)In contrast with many other conditions, such as

rheumatoid arthritis, diabetes and cancer, there is a paucity of biomarkers in OA to inform clinical decision making and to enable evaluation of treatments and other interventions. Furthermore, there are no biomarkers either to enable early detection of the condition, or to identify people who are most likely to progress to severe OA.

Biomarkers for OABiochemical markers

Best Pract Res Clin Rheumatol 2014;28:61-71

Imaging markers

X-ray and MRI measures being obtained in the FNIH OA Biomarkers Consortium.

The types of imaging biomarkers are numerical (joint space width [mm], volume of medial tibial cartilage [ml]) and categorical (Kellgren-Lawrence [KL] grade, MOAKS synovitis score). As long as they are objectively measured they can be a biomarker, otherwise, it is not a true biomarker.

Traditional imaging biomarkerAlthough a full understanding of OA requires

consideration of a range of biopsychosocial factors, our traditional method of defining clinical OA has relied upon plain radiography. Radiographic measures have been the traditional outcomes in studies involving diagnosis and progression of OA. FDA guidance and current gold standard for measuring clinical efficacy in disease modifying therapy development in OA is radiographic joint space narrowing (JSN). The JSN measure is currently recommended by both the FDA and European Agency for the Evaluation of Medicinal Products (EMEA) guidance documents as the imaging endpoint for clinical trials of disease-modifying OA drugs (DMOADs).

Issues for JSN as a biomarker for OAJSN indicate changes in bone, and only indirectly

measure alterations in cartilage. JSN is confounded by meniscal cartilage lesions and meniscal extrusion. JSN can be changed by positioning of the joint and has very

Musculoskeletal 395


small annual change. Bone marrow lesion and synovial abnormalities may go undetected. If targeted structures are synovium or bone marrow lesions, ascertaining its therapeutic benefit by the measurement of JSN may not be appropriate. JSN is poorly correlated with joint function.

Imaging biomarkers for cartilage morphologyCommon MR sequences used for quantification of

cartilage morphology are fat-suppressed T1-weighted spoiled gradient echo (SPGR or FLASH) and fat-suppressed T2-weighted fast spin echo (FSE).

Semi-quantitative joint scoringSemi-quantitative MRI-based scoring enables

evaluation of various OA features - integrity of articular cartilage, meniscus and ligaments, bone marrow abnormalities, synovitis and joint effusion, and cystic lesions and loose bodies (cartilage and bone fragments).

Advantage -- consider the whole knee instead of focusing on individual tissues, and exploit the proficiency of expert readers to judge the condition of the whole knee.

Disadvantage -- time consuming to perform, these scales have multiple subscales, and it is not at all clear whether and how these subscales should be combined.

Whole Organ Magnetic Resonance Imaging Score (WORMS)Knee Osteoarthritis Scoring System (KOSS)Boston-Leeds Osteoarthritis Knee Score (BLOKS)MRI osteoarthritis Knee Score (MOAKS)

Quantitative methodsCartilage volume measurement

Most straightforward parameterCartilage volume and thickness mappingPercent cartilaginous (or eroded) joint surface areaCartilage surface curvature (joint incongruity)Measurement precision (reproducibility) is critical. Because changes in cartilage morphology occur at a very slow rate, highly reproducible techniques are required.Normal -- 0.3% to 0.5% of cartilage is lost per yearOA -- 4% to 6%For more rapid indicators of disease progression

and treatment response, one must look upstream to earlier stages in the process of cartilage degeneration. Accordingly, there has been a great deal of interest in MRI markers of cartilage matrix damage.

Measurement of cartilage glycosaminoglycan content

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC)Chemical exchange saturation transfer (GAG-CEST)

T1ρSodium MRI

Cartilage water content and the integrity of the collagen matrix

T2 mappingDiffusion-weighted imagingDiffusion tensor imaging

3D MRI3D bone shape support its utility as a viable imaging

biomarker that can identify knees at risk of developing OA, of more rapid progression, and of eventually requiring arthroplasty. 3D bone shape also provides the possibility of more rapidly testing potentially promising treatments: the rate of bone shape change could be used as a metric of drug efficacy.

Issues of imaging biomarkersBone marrow lesion (BML), synovitis, meniscal lesion

It is not yet known how each of these tissues change with time, and with extent of disease, and how they interact with each other. MRI-measured BML and synovitis or synovial effusions and increasing symptoms have moderate to strong correlations. Between MRI cartilage loss or meniscal tears and symptoms have weak correlations. OA is a slow-moving disease, and the amount of change which occurs within a clinical study (typically of 1 year’s duration) is very small.

CartilageCartilage thickness changes by fractions of 1 mm per

year on average (total thickness is only 3-5 mm). It is about a ¼ of the width of a single pixel on the screen. Measuring such small changes is a challenge. It requires painstaking work, excellent measurement tools and the use of very large patient cohorts to establish statistical significance.

With technical aspectWe need adequate three-dimensional spatial

resolution (because the cartilage is relatively thin and has high curvature) and sufficient contrast-to-noise. Negligible chemical shift artifact is essential to permit accurate delineation of the bone-cartilage and synovial-cartilage interfaces.

3D bone shape support its utility as a viable imaging biomarker that can identify knees at risk of developing OA, of more rapid progression, and of eventually requiring arthroplasty. 3D bone shape also provides the possibility of more rapidly testing potentially promising treatments: the rate of bone shape change could be used as a metric of drug efficacy.

396 KCR 2019


References

1. Spain L, Rajoub B, Schluter DK et al. Biomarkers for knee osteoarthritis: new technologies, new paradigms. Int J Clin Rheumatol 2015;10:287-297

2. Hunter DJ, Nevitt M, Losina E, Kraus V. Biomarkers for osteoarthritis: Current position and steps towards further validation. Best Pract Res Clin Rheumatol 2014;28:61-71

3. Bauer DC, Hunter DJ , Abramson SB, e t a l . Classification of osteoarthritis biomarkers: a proposed approach. Osteoarthritis Cartilage 2006;14:723-727

4. Dieppe PA, Lohmander LS. Pathogenesis and management of pain in osteoarthr i t is. Lancet 2005;365:965-973

5. Creamer P. Osteoarthritis pain and its treatment. Curr Opin Rheumatol 2000;12:450-455

6. U.S. Department of Health and Human Services. Guidance for Industry: clinical development programs for drugs, devices, and biological products intended for the treatment of osteoarthritis (OA), 1999

7. Hunter DJ, Zhang YQ, Tu X, et al. Change in joint space width: hyaline articular cartilage loss or alteration in meniscus? Arthritis Rheum 2006;54:2488-2495

8. Pelletier JP, Cooper C, Peterfy C, et al. What is the predictive value of MRI for the occurrence of knee replacement surgery in knee osteoarthritis? Ann Rheum Dis 2013;72:1594-1604

9. Li W, Abram F, Pelletier JP, et al. Fully automated system for the quantification of human osteoarthritic knee joint effusion volume using magnetic resonance imaging. Arthritis Res Ther 2010;12:R173

10. Krasnokutsky S, Belitskaya-Lévy I, Bencardino J, et al. Quantitative magnetic resonance imaging evidence of synovial proliferation is associated with radiographic severity of knee osteoarthritis. Arthritis Rheum 2011;63:2983-2991

11. Journal of Biomedical Graphics and Computing, 2013, Vol. 3, No. 1

12. Neogi T, Felson DT. Osteoarthritis: Bone as an imaging biomarker and treatment target in OA. Nat Rev Rheumatol 2016;12:503-504.

13. Barr AJ, Dube B, Hensor EM. The relationship between three-dimensional knee MRI bone shape and total knee replacement-a case control study: data from the Osteoarthritis Initiative. Rheumatology (Oxford) 2016;55:1585-1593

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Cartilage repair

Ji hoon Bae Korea University Guro Hospital, Korea. [email protected]

Cartilage damaged by trauma has a limited capacity to regenerate. Cartilage repair generally is indicated if nonoperative methods fail to relieve pain and mechanical symptoms. Treatment options include debridement, marrow stimulation, osteochondral transplantation to fill the defect, cell-based therapy, and the use of growth factors or pharmacologic agents. The choice of procedure is based primarily on the size of the lesion and the activity demands of the patient.

For patients with minimal symptoms and small lesions (< 2 cm2) in areas of limited weight bearing, arthroscopic debridement to remove loose flaps or edges that impinge in the joint can provide short-term relief. The goal of arthroscopic debridement and lavage is to reduce the inflammation and mechanical irritation within the joint. Debridement may include smoothing of the fibrillated articular surface (chondroplasty), meniscal trimming, shaving of osteophytes, and removal of inflamed synovium. Joint lavage is thought to reduce synovitis and pain by washing fragments of cartilage and calcium phosphate crystals from the knee. Results after debridement are not as good in patients with significant knee arthritis.

Abrasion chondroplasty or microfracture techniques may stimulate a reparative process for small lesions (< 2 cm2) in low-demand patients. These procedures which involve penetration of the avascular cartilage layer into the vascular subchondral bone to stimulate extrinsic repair, are well supported in the literature. Improvement in symptoms has been reported in 60% to 70% of patients after abrasion or microfracture, but the fibrocartilaginous repair appears to deteriorate with time, beginning at about 18 months after surgery. Results are significantly better in patients younger than 40 years than in patients older than 40 years. Advantages of microfracture are the simplicity of the procedure, the relatively low cost, and the low risk of patient morbidity. It also does not prevent the later use of other, more complex procedures. Five factors have been identified

as affecting the quality of the cartilaginous repair tissue after microfracture of a chondral defect: (1) during debridement, the calcified cartilage layer must be removed, but the abrasion of the subchondral bone must be avoided; (2) a 1- to 2-mm bridge of bone must be left between penetrations to allow connective tissue to fill the defect and adhere to the base of the defect; (3) joint function must be maintained after surgery by the use of early continuous passive motion; (4) protected weight bearing must be strictly enforced, depending on the location of the lesion; and (5) any significant abnormality in the mechanical axis must be corrected in conjunction with the microfracture procedure. In an attempt to improve long-term results, principles of tissue engineering currently are being applied to microfracture techniques (“enhanced microfracture”). Autologous matrix-induced chondrogenesis (AMIC) combines microfracture with the use of an exogenous scaffold to stabilize the marrow clot and allow the ingrowth of mesenchymal stem cells. Several such matrices are commercially available in Korea, but currently, there are few studies reporting the performance of these enhancements.

For larger lesions or multiple lesions, especially in high-demand patients, restorative procedures such as osteochondral autograft transfer, osteochondral allografting, and autologous chondrocyte implantation usually are indicated. Osteochondral autografts can be transplanted into damaged areas (up to 2 cm2) from areas of less weight bearing on the femoral condyle as either a single large bone plug or multiple small plugs (mosaicplasty).

For lesions up to 10 cm or for multiple lesions, autologous chondrocyte implantation can be an effective restorative procedure. This procedure is done in two stages. First, a small amount of articular cartilage or chondral bone is removed arthroscopically for growing of the autologous chondrocytes. Then, usually 3 to 6 weeks later, an open procedure is done to implant the

398 KCR 2019


cells in the chondral defect. A periosteal graft is sutured over the defect, and the chondrocytes are injected under the graft into the defect. The injection site is closed with one or two additional sutures and sealed with fibrin glue. Malalignment, ligament instability, and meniscal deficiencies must be corrected before or at the time of autologous chondrocyte implantation. Good to excellent results have been reported in 80% to 89% of patients at 2 to 9 years after surgery. Some authors have reported better results in patients younger than 40 years of age at the time of surgery, whereas others have found no differences in the outcomes of autologous chondrocyte implantation. Autologous chondrocyte implantation also has been reported to be successful in treating large (average approximately 500 mm2) chronic articular cartilage lesions. The most common complications are articular adhesions (2%) and detachment or delamination (< 1%). Because of the frequency of periosteal hypertrophy and the difficulty of harvesting the periosteum and sewing it in place, bioabsorbable collagen covers were developed as an alternative (second-generation autologous chondrocyte implantation). The implantation of cultured chondrocytes in suspension, as is done in both periosteal and collagen covers, raised concerns about uneven distribution of the chondrocytes in the defect and the possibility of cell leakage. To avoid these problems, chondrocytes have been seeded directly onto biodegradable scaffolds that are collagen based (e.g., MACI, Genzyme Biosurgery, Cambridge, MA) or hyaluronan based (e.g., Hyalograft-C, Anika Therapeutics, Bedford, MA; BioCart II, ProChon Biotech, Woburn, MA; Cartilix, polymer hydrogel, Biomet, Warsaw, IN; Cartipatch, agarose-alginate matrix, TBF Tissue Engineering, Mions, France). Because these membrane scaffolds are naturally “sticky,” they can be placed into the defect arthroscopically without additional fixation or covering.

The field of cartilage tissue engineering has advanced quickly in the past decade, and many novel approaches have been developed. The future of managing cartilage defects lies in providing biologic solutions through cartilage regeneration. Laboratory and clinical studies have examined the management of larger lesions using tissue-engineered cartilage. Regenerated cartilage can be derived from various cell types, including chondrocytes, pluripotent stem cells, and mesenchymal stem cells. Common scaffolding materials include proteins, carbohydrates, synthetic materials, and composite polymers. Scaffolds may be woven, spun into nanofibers, or configured as hydrogels. Chondrogenesis may be enhanced with the application of chondroinductive growth factors. Bioreactors are being developed to enhance nutrient delivery and provide mechanical stimulation to tissue-engineered cartilage ex vivo. The multidisciplinary approaches

currently being developed to produce cartilage promise to bring to fruition the desire for cartilage regeneration in clinical use.

However, although early results have been promising, engineered cartilage with properties identical to those of native cartilage is currently unavailable. Significant obstacles remain, and the future of cartilage engineering lies in addressing issues such as ensuring optimal and stable chondrogenic cellular phenotype and cartilage matrix production, preventing matrix and cellular degradation, promoting appropriate cartilage integration, and delivering antioxidant and anti-inflammatory factors to provide durable cartilage constructs. Challenges include regulatory hurdles, as well as safety, viability, and potential immunogenicity of the engineered tissue. The variety and depth of emerging technologies have the potential to revolutionize the field of cartilage regeneration, which is expected to develop and flourish in the next decade.

References

1. Gobbi A, Whyte GP. Long-term clinical outcomes of one-stage cartilage repair in the knee with hyaluronic acid-based scaffold embedded with mesenchymal stem cells sourced from bone marrow aspirate concentrate. Am J Sports Med 2019;47:1621-1628

2. Jones KJ, Kelley BV, Arshi A, McAllister DR, Fabricant PD. Comparative effectiveness of cartilage repair with respect to the minimal clinically important difference. Am J Sports Med 2019:363546518824552

3. Gao L, Orth P, Cucchiarini M, Madry H. Autologous matrix-induced chondrogenesis: a systematic review of the clinical evidence. Am J Sports Med 2019;47:222-231

4. Orth P, Gao L, Madry H. Microfracture for cartilage repair in the knee: a systematic review of the contemporary literature. Knee Surg Sports Traumatol Arthrosc 2019

5. Cavinatto L, Hinckel BB, Tomlinson RE, Gupta S, Farr J, Bartolozzi AR. The role of bone marrow aspirate concentrate for the treatment of focal chondral lesions of the knee: a systematic review and critical analysis of animal and clinical studies. Arthroscopy 2019;35:1860-1877

6. Solheim E, Hegna J, Strand T, Harlem T, Inderhaug E. Randomized study of long-term (15-17 years) outcome after microfracture versus mosaicplasty in knee articular cartilage defects. Am J Sports Med 2018;46:826-831

7. Krill M, Early N, Everhart JS, Flanigan DC. Autologous chondrocyte implantation (ACI) for knee cartilage defects: a review of indications, technique, and outcomes. JBJS Rev 2018;6:e5

8. Kraeutler MJ, Belk JW, Purcell JM, McCarty EC.

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Microfracture versus autologous chondrocyte implantation for articular cartilage lesions in the knee: a systematic review of 5-year outcomes. Am J Sports Med 2018;46:995-999

9. Ogura T, Bryant T, Mosier BA, Minas T. Autologous chondrocyte implantation for bipolar chondral lesions in the tibiofemoral compartment. Am J Sports Med 2018;46:1371-1381

10. Mundi R, Bedi A, Chow L, Crouch S, Simunovic N, Sibilsky Enselman E, et al. Cartilage restoration of the knee: a systematic review and meta-analysis of level 1 studies. Am J Sports Med 2016;44:1888-1895

11. Wylie JD, Hartley MK, Kapron AL, Aoki SK, Maak TG. Failures and reoperations after matrix-assisted

cartilage repair of the knee: a systematic review. Arthroscopy 2016;32:386-392

12. Sommerfeldt MF, Magnussen RA, Hewett TE, Kaeding CC, Flanigan DC. Microfracture of articular cartilage. JBJS Rev 2016;4

13. Knutsen G, Drogset JO, Engebretsen L, Grontvedt T, Ludvigsen TC, Loken S, et al. A randomized multicenter trial comparing autologous chondrocyte implantation with microfracture: long-term follow-up at 14 to 15 years. J Bone Joint Surg Am 2016;98:1332-1339

14. Tuan RS, Chen AF, Klatt BA. Cartilage regeneration. J Am Acad Orthop Surg 2013;21:303-311

400 KCR 2019

Musculoskeletal Sep 18, W

ed

Musculoskeletal 08:00 - 09:30 Grand Ballroom 104

Update on Joint Imaging

Chairperson(s)Sungjun Kim Gangnam Severance Hospital, KoreaYoung Cheol Yoon Samsung Medical Center, Korea

SS 02 MS-01 08:00Ruling out rotator cuff tear in shoulder radiograph series using deep learning: redefining the role of conventional radiographYoungjune Kim, Dongjun Choi, Kyong Joon Lee, Yusuhn Kang, Joong Mo Ahn, Eugene Lee, Joon Woo Lee, Heung Sik Kang Seoul National University Bundang Hospital, Korea. [email protected]

PURPOSE: To develop a deep learning algorithm that can identify patients in which unnecessary advanced imaging may be avoided in clinically suspected rotator cuff tear, using conventional radiographs.MATERIALS AND METHODS: To develop the algorithm, 6793 shoulder radiograph series examined between January 2015 and June 2018, labeled based on ultrasound or MRI examined within 90 days, and clinical information (age, sex, dominant side, history of trauma, degree of pain) were used. Its output was the probability of supraspinatus/infraspinatus complex tear > 50% of tendon thickness. The operating point corresponding to a sensitivity of 98% was set to achieve high negative predictive value (NPV) and low negative likelihood ratio (LR-). The performance of the algorithm was tested with 1095 radiograph series examined between July and December 2018. Subgroup analysis was performed to identify factors associated with negative test result and false omission rate; tested variables included clinical information, radiography vendor, and reference standard modality.RESULTS: With assistance of the deep learning algorithm, 33.4% patients with clinically suspected rotator cuff tear could potentially have a chance to avoid unnecessary advanced imaging. Sensitivity, NPV, and LR- was 96.3%, 95.9%, and 0.07, respectively. The subgroup analysis showed that patients with age < 60 years and absence of trauma history would benefit greater from the deep learning algorithm. False omission rates were not significantly different among the various subgroups except for the reference standard modality.CONCLUSION: The deep learning algorithm can help avoid unnecessary advanced imaging in considerable portion of patients with clinically suspected rotator cuff tear.

SS 02 MS-02 08:10Can ultrasonography (US) be useful in planning surgery for de Quervain's tenosynovitis?: emphasis on anatomical course of superficial radial nerve (SRN) and dominant pathologic tendonJoonsuk Park, Eun Kyung Khil, Sung-Jae Kim, Jung-Ah Choi, Ayeon Kim Hallym University Dongtan Sacred Heart Hospital, Korea. [email protected]

PURPOSE: Injury of the SRN can be a major cause of residual pain after surgical treatment of de Quervain’s tenosynovitis. We performed preoperative US to detect anatomical course of SRN and dominant pathologic tendon on the first extensor compartment.MATERIALS AND METHODS: We prospectively studied 25 patients (29 wrists) with de Quervain’s tenosynovitis, who underwent surgical release of the first extensor compartment. Prior to surgery, US examination were performed to evaluate the presence of dominant pathologic tendon, subcompartment analysis regarding septum, number of SRN on area of surgical incision, and anatomical running course of SRN. These variables were also checked intraoperatively. Descriptive statistics were used for demographic data. Cohen’s Kappa values were calculated to investigate agreement between US and surgical findings.RESULTS: There were 10 men, 15 women with mean age 47.8 years (range, 26-67). All Kappa statics were statistically significant (p < 0.05). For the dominant pathologic tendon, there were two cases (6.9%) of APL, 11 cases (37.9%) of EPB and 16 cases (55.2%) of non-dominant tendon, with a K-value of 0.94. For the subcompartment analysis, there were 10 cases without septum (34.5%), 8 cases (27.6%) with incomplete septum, and 11 cases (37.9%) with complete septum, for which K-value was 0.95. For number of observed SRN under surgical incision, most cases were seen with one branch (n = 22, 75.9%), five cases (17.2%) with two branches, and two cases without nerve branch, for which K-value was 0.77. For the anatomical course of SRN (K-value = 0.784), most SRNs were detected to cross the proximal radial to distal ulnar aspect of the first extensor compartment.CONCLUSION: Preoperative US evaluation can be useful in detecting the dominant pathology between the APL and EPB tendons, presence of the septum and its morphology, number and anatomical running course of SRN branches before surgery for de Quervain’s tenosynovitis. Therefore, preoperative US could be helpful to prevent SRN injury during surgery.

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SS 02 MS-03 08:20 Deep learning-based automatic fat quantification of supraspinatus muscle: quantitative comparison of a single slice at Y-view versus total MR slicesHyunjung Yeoh, Hye Jin Yoo, Sung Hwan Hong, Ja-Young Choi, Hee Dong Chae, Ji Eun Kim, Ji Hee Kang, Jin sun Lee Seoul National University Hospital, Korea. [email protected]

PURPOSE: To develop a deep learning-based automatic fat quantification from 6-point Dixon sequence (6-Dixon) and to determine whether the standard assessment for muscle fatty infiltration using a single image slice is indicative of the entire fatty infiltration in supraspinatus muscle (SSm).M AT E R I A L S A N D M E T H O D S : T h i s s t u d y retrospectively analyzed 72 MR images with (a) extended oblique sagittal T1-weighted images (T1WI) and (b) fat fraction (FF) map generated from 6-point Dixon sequence including total SSm. A deep learning model-based on the U-Net convolutional network architecture was developed to perform automatic segmentation. Subjects were divided into 3 groups (score 0, n = 49; score 1, n = 17; score 2, n = 6) according to the Fuchs scores of SSm based on T1WI. Deep learning-derived FFs of SSm on a single slice at Y-view (FFy) and total MR slices (FFt) were compared in 3 groups. We also compared FFy and FFt according to the retraction grade of a torn tendon (grade 1, n = 59; grade 2, n = 5; grade 3, n = 8). Performance of the automatic segmentation was evaluated on Dice coefficient overlap with the manual segmentation.RESULTS: The models produced strong Dice coefficient of 0.828 and accuracy of 0.996. The average of FFy and the average of FFt for each Fuchs score were as follows: score 0, 17.49 and 19.81%; score 1, 16.74 and 28.56%; score 3, 18.02 and 43.11%. FFy was

statistically different from FFt in all groups (score 0, p = 0.011; score 1, p = 0.001; score 2, p = 0.028). The difference between FFy and FFt was up to 39.33% in Fuchs score 2 group. In all retraction grade, FFt was significantly higher than FFy (grade 1, p < 0.001; grade 2, p = 0.043; grade 3, p = 0.017). Median values of FFt were 19.18%, 35.82%, and 36.86% for each grade.CONCLUSION: A deep learning-based fat quantification can achieve fully automated and accurate evaluation for muscle fat fraction in SSm. A single sagittal slice at Y-view is not indicative of the total fat fraction in SSm, especially in group with severe fatty infiltration. Also, the fat fraction could be influenced by the retraction grade of a torn tendon.

SS 02 MS-04 08:30Increased prevalence of pincer-type morphology including acetabular overcoverage in patients with type II Scheuermann’s diseaseYoungjun Chon1, Jaehyuck Yi1, Tae Eun Kim2, Hoseok Lee3, Jin young Kim1, Sungmin Moon1, Hye Min Son1 1Keimyung University Dongsan Medical Center, 2Daegu Fatima Hospital, 3Kyungpook National University Hospital, Korea. [email protected]

PURPOSE: Changes of the spinopelvic alignment have been recognized as a cause of hip pathologies, especially for patients with spine pathologies. The purposes of this study were to verify the prevalence of pincer-type morphology including acetabular overcoverage in type II Scheuermann’s disease and to show the relationship between the degree of changes in spine morphology and pincer-type morphology in type II Scheuermann’s disease.MATERIALS AND METHODS: This study included 44 patients with type II Scheuermann's disease who underwent the pelvis AP view between March 2014 and

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March 2019. Patients with prior hip surgery or childhood hip problems were excluded from the study. There were 70 hips from 35 male patients and 18 hips from 9 female patients. According to the degree of changes in spine morphology (wedged configuration of the thoracolumbar spine, loss of the normal lumbar lordosis, endplate irregularities, and Schmorl’s nodes), the patients were categorized into two groups: probable (Group A) and suspected (Group B). The features of pincer-type morphology including acetabular overcoverage were determined by radiographic signs, including lateral center-edge angle (LCEA) ≥ 40°, acetabular index ≤ 0°, coxa profunda, protrusio acetabuli, crossover sign, posterior wall sign, or ischial spine sign.RESULTS: In this study, the mean age of all patients was 35.4 years (range, 20-60 years). There were 17 patients in Group A and 27 patients in Group B. The prevalence of LCEA ≥ 40° in type II Scheuermann disease was 23.8%, in which Group A and Group B resulted in 41.2% and 12.9%. The prevalence of LCEA ≥ 40° in type II Scheuermann disease was significantly higher, compared with the result from previous studies of asymptomatic Asian population (2.0% to 9.1%). The prevalence of LCEA ≥ 40°, posterior wall sign in group A was significantly higher than that in group B (p < 0.05). There was no statistically significant difference between two groups in terms of acetabular index ≤ 0°, coxa profunda, protrusio acetabuli, crossover sign, and ischial spine sign.CONCLUSION: In type II Scheuermann disease, the prevalence of pincer-type morphology including acetabular overcoverage was higher than that in asymptomatic Asian population. Furthermore, the patients with more severe morphologic changes in spine showed higher probability of pincer- type morphology.

SS 02 MS-05 08:40Diagnostic performance of dual-energy CT with water-hydroxyapatite material decomposition for detection of bone marrow edema in non-traumatic hipWookon Son, Chankue Park, Hee Seok Jeong Pusan National University Yangsan Hospital, Korea. [email protected]

PURPOSE: To assess the diagnostic performance of dual-energy CT with water-hydroxyapatite (HAP) material decomposition for detection of bone marrow edema in patients with non-traumatic hip pain.MATERIALS AND METHODS: Forty patients (mean age, 58 years; M:F = 16:24) who underwent dual-energy CT with water-HAP material decomposition and MRI within 1 month between April 2018 and February 2019, with hip pain, without trauma, were enrolled.

Two independent readers (reader 1, experienced in water [HAP] image; reader 2, inexperienced), blinded to clinical and MRI information, retrospectively evaluated 80 hip joints (normal, 32 joints; osteonecrosis, 25 joints; osteoarthritis, 18 joints; others, 5 joints) for the presence, extent (1, femoral head involved; 2, head and neck involved; 3, head to intertrochanter involved), and severity (1, mild edema; 2, moderate edema; 3, severe edema) of bone marrow edema on dual-energy water (HAP) images. Water mass density (mg/cm3) on water (HAP) images were determined with region-of-interest-based quantitative analysis. MRI served as the standard of reference for presence of bone marrow edema.RESULTS: Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of readers 1 and 2 in the identification of bone edema at water (HAP) image were 85% and 85%, 93% and 73%, 89% and 79%, 92% and 76%, and 86 and 83%, respectively. Water mass density from water (HAP) images increased as the extent widened and severity increased (both ps < 0.001). The area under the receiver operating characteristic curve was 0.96 for reader 1 and 0.91 for reader 2 in differentiation of the presence of bone marrow edema from no edema. The optimal water mass density to classify the presence of bone marrow edema for reader 1 was 951.1 mg/cm3 with sensitivity of 93% and specificity of 93%. Inter-observer agreement was good for presence of bone marrow edema (κ = 0.62) and excellent for value of water mass density (ICC = 0.89).CONCLUSION: Dual-energy water (HAP) images had good diagnostic performance for detection of bone marrow edema in patients with non-traumatic hip pain.CLINICAL RELEVANCE: Dual-energy CT with water-hydroxyapatite material decomposition depicts bone marrow edema in patients with non-traumatic hip pain and may serve as an alternative to MRI in select patients.

SS 02 MS-06 08:50Patient-specific guide for reverse total shoulder replacement using 3D printingKyounghwan Koh1, Myungjin Shin1, Younsang Hwang2, Doyun Lee2, Hwayong Lee2, Guk Bae Kim1, Junoh Ryu2, Inho Jeon1 1Asan Medical Center, 2Anymedi Inc., Korea. [email protected]

BACKGROUND: Reverse total shoulder arthroplasty (RTSA) is a surgical option for several pathologies including glenohumeral arthropathy with irreparable rotator cuff tear, complex fractures in the elderly, failed anatomic arthroplasty. To prevent glenosphere loosening and scapular notching, position of baseplate has been

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emphasized. Hence the location and the angle of guide pin is utmost important for the long-term prognosis. However, limited surgical field and exposure and the current free-hand technique for guide pin depend highly on the surgeon’s experience.EVALUATION: 3D stereolithography (STL) model of the patient’s scapula was generated from the CT image of the patient. Using the 3D model of the base plate and the scapula model of the patient, the position and angle of the reaming-guide pin, and the optimized length and insertion angle of the peripheral screws was modeled considering the deformity of the glenoid and individual anatomy of the scapula. A 3-D guiding platform for reaming-guide pin and screws were designed so that it fits accurately to the glenoid surface. The 3-D guiding platform should have enough length of guiding hole and should be small to apply with a limited surgical exposure at the same time. The designed guiding platform model was printed using a Projet3510 3D printer using M3 crystal.RESULTS: Four patients with shoulder disease over 60 years of age were enrolled. Although conformity between the 3D printed guiding platform and the glenoid was enough to insert the reaming-guide pin and drill accurately, there was still room for improvement in seating the guiding platform on the glenoid since the individual anatomic variance, surrounding soft tissue, and limited visual field. Compared to preoperative plan, center peg showed the deviation less than 1 degree in insertion angle. Inferior translation, retroversion, and tilting of base plate was almost same as preoperative planning.CONCLUSION: With this 3D printed guiding platform, reaming-guide pins can be inserted as the planned position and angle regardless of the varying surgical environments, so that improved results are expected in operative consistency and long-term prognosis.

A C

Figure 1. (A) Coronal, (B) axial and (C) sagittal CT images.

Figure 2. Guide pins and peripheral screws modeled on 3D scapula and baseplate.

Figure 5. Operation using surgical guide.

SS 02 MS-07 09:00Superolateral Hoffa’s fat pad edema: relationship with cartilage T2* value and patellofemoral maltrackingSeul Ki Lee1, Joon-Yong Jung2, Hyerim Park2, Seung Eun Lee2, Aram Jo2 1The Catholic University of Korea, St. Vincent’s Hospital, 2The Catholic University of Korea, Seoul St. Mary’s Hospital, Korea. [email protected]

PURPOSE: To determine (1) the association between superolateral Hoffa’s fat pad (SHFP) edema and early cartilage degeneration using T2* mapping and (2) whether patellofemoral maltracking is related to cartilage T2* values or SHFP edema.MATERIALS AND METHODS: In this retrospective study, 68 patients (71 knees) with anterior knee pain who had undergone 3-Tesla magnetic resonance imaging (MRI) were enrolled. Cartilage T2* values in

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medial and lateral patellofemoral compartment as well as patellofemoral maltracking parameters (trochlear angle, sulcus angle, patellar tilt angle, tibial tuberosity-to-trochlear groove [TT-TG] distance, and patellar-tendon to patellar-length [PT-PL] ratio) were compared between case group (24 knees with SHFP edema) and control group (47 knees without the edema). The associations between the patellofemoral maltracking and the cartilage T2* values as well as the SHFP edema were investigated using logistic and linear regression analyses.RESULTS: The case group showed significantly higher cartilage T2* value in the lateral patellar facet, wider sulcus angle, greater TT-TG distance, and higher PT-PL ratio than the control group. Both SHFP edema and higher cartilage T2* value in the lateral patellar facet were significantly associated with wider sulcus angle, greater TT-TG distance, and higher PT-PL ratio.CONCLUSION: SHFP edema appears to be associated with inherent cartilage degeneration in the lateral patellar facet. Patellofemoral maltracking might be a risk factor for SHFP edema and early cartilage damage in the lateral patellar facet.

SS 02 MS-08 09:10 Longitudinal change of long head of the biceps brachii tendon on MRI after rotator cuff repairSeung Eun Lee, Joon-Yong Jung The Catholic University of Korea, Seoul St. Mary’s Hospital, Korea. [email protected]

PURPOSE: To determine the relationship between the alteration of long head of biceps tendon (LBT) after rotator cuff repair surgery and the immediate postoperative condition of shoulder elements on magnetic resonance (MR) images.MATERIALS AND METHODS: Two-hundred nineteen patients (F:M = 148:71; mean age, 57.4 years) who had undergone the rotator cuff repair surgery and examined postoperative MR more than twice by one year after surgery were included. The LBT was graded with 6-severity scale: normal, mild, moderate, severe intratendinous signal change, partial tear and complete tear. The deterioration of LBT was defined by increased grade or extent of the LBT abnormality between first and second postoperative MR. To find the possible association between postoperative MR findings and LBT deterioration, the fatty degeneration of superior cuff (supraspinatus and infraspinatus muscles) and subscapularis muscle, initial condition of LBT, subluxation of LBT, superior labral tear and adhesive capsulitis were evaluated on the initial postoperative MRI. Additionally, 63 patients (F:M = 39:24; mean age,

57.3 years) with long-term follow-up MRI over 3 times, the association between preservation or improvement of LBT and aforementioned factors were analyzed. The logistic regression was used to evaluate the association between the alteration of LBT and the postoperative factors.RESULTS: Among total 219 patients, 48.9% (n = 107) showed LBT deterioration. In univariate analysis, the fatty degeneration of superior cuff (p = 0.002) and subscapularis muscle (p = 0.026) were associated with LBT deterioration while the subluxation of LBT showed a tendency (p = 0.059). In multivariate analysis, only the fatty degeneration of superior cuff was significantly associated with LBT deterioration. In patients with long-term follow-up (1166.3 ± 610.3 days), 8, 23 and 32 were improved, stable or further deteriorated, respectively. The fatty degeneration of superior cuff and initial condition of LBT showed significant association with long-term preservation of LBT in multivariate analysis (p = 0.007, p = 0.028), respectively.CONCLUSION: The degree of fatty degeneration in rotator cuff is associated with the LBT deterioration on 1 year MRI follow-up and the LBT preservation in long-term MRI follow-up.

SS 02 MS-09 09:20 Deep learning-based metal artifact reduction in CT for total knee arthroplastyJimin Lee1, Hee Dong Chae2, Hyungjoo Cho1, Sung Hwan Hong2, Ja-Young Choi2, Hye Jin Yoo2, Sung-Joon Ye1 1Seoul National University, 2Seoul National University Hospital, Korea. [email protected]

PURPOSE: To investigate the metal artifact reduction (MAR) performance of deep learning (DL)-based MAR technique in the evaluation of postoperative CT of total knee arthroplasty (TKA) patients.MATERIALS AND METHODS: The training dataset consisted of 640 image pairs obtained from 10 lower extremity CT scans without a metal prosthesis. Each image pair consists of a metal artifact-free image with a virtual metal shape embedded in the original image and a metal artifact image simulated through sinogram handling. Our DL network is a convolutional neural network with encoder-decoder structure and skip connections. The summation of MSE and SSIM losses were implemented for parameter updating. For the test dataset, we used 10 lower extremity CT examinations from 10 patients who had a previous history of TKA (7 patients with unilateral TKA; 3 patients with bilateral TKA), and a total of 13 knee joints were used for analysis. To evaluate the metal artifacts quantitatively,

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the area, mean attenuation, and artifact index (AI) within the dark streak artifacts were calculated in the original, O-MAR, and DL-MAR images. For qualitative analysis, images were rated with a 5-point Likert scale regarding the degree of overall metal artifacts, conspicuity of bone cortex and trabeculae, and assessment of soft tissue around the prosthesis. Continuous variables were compared between different MAR protocols using the repeated measures ANOVA and qualitative grading results were analyzed by using the Friedman test.RESULTS: The O-MAR showed a 24% reduction in metal artifact area, while the DL-MAR showed an area reduction of more than 99%, almost completely eliminating the dark streak artifact. In terms of mean attenuation and AI, DL-MAR also showed better performance than O-MAR (p < 0.001). In qualitative analysis, DL-MAR showed significantly lower overall metal artifacts (p = 0.008) and better bone delineation (p = 0.020) compared to O-MAR. However, there was no significant difference in the assessment of soft tissue between two MAR protocols (p = 0.054), and DL-MAR showed unusual blurring of periarticular soft tissue.CONCLUSION: The DL-MAR technique has been successfully developed and shown comparable performance with conventional projection completion algorithm.


Update on Joint Imaging

Chairperson(s)Min Hee Lee Asan Medical Center, KoreaSuk-Joo Hong Korea University Guro Hospital, Korea

SS 04 MS-01 09:50Role of shoulder CT imaging in diagnosis of acromioclavicular and sternoclavicular joint injury in patients with clavicle fractureJi soo Oh, In Sup Song, Beum Jin Kim, Mi-Sook Lee, Jinok Choi Presbyterian Medical Center, Korea. [email protected]

PURPOSE: Since spiral CT has been available, shoulder CT is routinely performed in patients where clavicle fracture is suspected. Shoulder CT allows detection of not only clavicle fracture but also evaluation of acromioclavicular (AC) and sternoclavicular (SC) joint injury. We investigated the incidence of AC joint and/or SC joint injury in patients with clavicle fracture, which reported only three cases before.MATERIALS AND METHODS: 82 patients with clavicle fracture undertook shoulder CT between January 2017 and March 2019. We divided the clavicle fracture sites as proximal 1/3, middle 1/3 and distal 1/3. Then we evaluated the ipsilateral AC and SC joint asymmetry by comparing to the uninjured contralateral joints.RESULTS: 42 clavicle fracture patients (51%) had asymmetric AC and/or SC joint space. 40 patients (49%) had symmetric AC and SC joint on both sides. Among 42 patients with clavicle fracture and AC or SC joint dislocation, 6 patients had proximal clavicle fractures, five (83%) of them were combined with SC joint dislocation and one (17%) had SC and AC joint dislocation. 16 patients had mid clavicle fracture. 8 (50%) of them were combined with SC joint dislocation, 5 (31%) with AC joint dislocation, 3 (19%) combined with SC and AC joint dislocation. 19 patients had distal clavicle fracture. 8 (42%) was with SC joint dislocation, 6 (32%) with SC and AC joint dislocation, and 5 (26%) with AC joint dislocation. The SC joint dislocation was most common, regardless of the location of the clavicle fracture.CONCLUSION: Although it was reported rarely, high incidence of AC or SC joint dislocation was found in clavicle fracture patients. Therefore, when assessing the clavicle fracture in shoulder CT, it is advisable to also examine ipsilateral SC and AC joints.

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SS 04 MS-02 10:00MR evaluation of the meniscal flounce in the knee: association with the meniscal tear, knee joint effusion and angleHyojin Kim, Joong Mo Ahn, Youngjune Kim, Yusuhn Kang, Eugene Lee, Joon Woo Lee, Heung Sik Kang Seoul National University Bundang Hospital, Korea. [email protected]

PURPOSE: To determine the association of the meniscal flounce (MF) with the location and pattern of the meniscal tear, amount of joint effusion, and joint angle in the knee.MATERIALS AND METHODS: Among 651 consecutive knee magnetic resonance images (MRI) examined between July 2015 and March 2016, patients with age ≥ 17 years, without history of knee surgery, and without infectious arthritis, neoplasm, or moderate to severe osteoarthritis of the knee were included. Thus, 283 MRIs of 280 patients were finally reviewed. MF was considered positive if shown as S wavy appearance of the free edge of the meniscus on the sagittal images of fluid-sensitive sequences. Presence of meniscal tear was checked and if present, its location (medial or lateral meniscus; anterior root, anterior horn, body, posterior horn, posterior root, or meniscocapsular attachment) and pattern (longitudinal-vertical, horizontal, radial, or complex) were recorded. Amount of the joint effusion was measured as physiologic, small, moderate, or large amount. Knee joint angle was measured between the long axis of the femur and the tibia on the sagittal images. Fisher exact test, Cochran-Armitage trend test, and t test were performed to compare the findings in patients with MF with those in age and sex-matched patients without MF. Decision tree analysis was performed to determine the most significant factor of MF.RESULTS: MF was present in 11% (31 of 30 patients; M:F = 15:15; mean age, 53.0 years; age range, 27-76 years) of adult population (283 of 280 patients; 147/283, 52% in normal menisci, 136/283, 48 % in torn menisci). MF was detected only in the medial menisci (MM). About 81% of MF was present in the torn menisci. The presence of MF was significantly associated with tears at the body (p = 0.007), posterior horn (p = 0.001), and meniscocapsular attachment (p = 0.002) of the MM. Patterns of meniscal tear, amount of knee joint effusion, and joint angle were not associated with the MF. Decision tree analysis revealed that posterior horn tear of MM was the most significant predictor of MF.CONCLUSION: MF can be present in both normal and torn menisci, and the most significant injury associated with MF was tear at the posterior horn of MM.

SS 04 MS-03 10:10Diagnostic accuracy of dual-layer detector CT using calcium suppressed images for the detection of bone marrow edema in wristJi-Eun Kim, Hye Jin Yoo, Hee Dong Chae, Ja-Young Choi, Sung Hwan Hong, Ji Hee Kang, Hyunjung Yeoh Seoul National University Hospital, Korea. [email protected]

PURPOSE: To evaluate the performance of calcium suppressed images (CaSupp) obtained by dual-layer detector computed tomography (DLCT) for the detection of bone marrow edema (BME) in patients with wrist pain.MATERIALS AND METHODS: We retrospectively analyzed 49 patients with wrist pain (44 distal radius fractures, 2 carpal bone fractures, 2 scaphoid nonunion advance collapses, 1 Kienböck disease), who underwent both DLCT and MRI. Two blinded and independent readers evaluated CaSupp images for evaluating BME by using color-coded maps. Using MRI images as the reference standard, the sensitivity and specificity of CaSupp images were analyzed for detecting BME of radius, ulna, and carpal bones.RESULTS: On MRI, 44 distal radius and 30 distal ulna fractures were found. In detecting BME of radius and ulna, two readers showed 100% of agreement. When CaSupp images were compared with MRI images, sensitivity and specificity for detecting BME were both 100% for radius, and 88% and 87.5% for ulna, respectively. For carpal bone, BME was found in 8 of 44 radius fractures and 5 of patients with only carpal bone abnormalities on MRI. Those carpal bone BMEs were detected on CaSupp images with following diagnostic accuracy: sensitivity, 92.8% for reader 1 and 64.2% for reader 2; specificity, 88.5% in both readers. For detection of carpal bone BME, two readers showed moderate agreement (agreement 75.5%, kappa value 0.43).CONCLUSION: CaSupp images reconstructed from DLCT enabled detection of BME in fractured distal radius and ulna with substantially high diagnostic accuracy when compared to MRI images. However, CaSupp demonstrated limited performance in visualization of BME of carpal bone pathologiesCLINICAL RELEVANCE: CaSupp images showed similar performance in visualization and detection of BME in wrist, including incomplete fracture compared with MRI. CaSupp images is expected to be a promising technique to demonstrate BME in wrist.

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edSS 04 MS-04 10:20The diagnostic performance of digital tomosynthesis in comparison with radiography and CT in the detection of avascular necrosis involving femoral heads as good screening tool Seunghun Lee1, Juyeon Kang2, Jeong Ah Ryu1, Yee-Suk Kim1 1Hanyang University College of Medicine, 2Hanyang University Seoul Hospital, Korea. [email protected]

BACKGROUND: Early diagnosis of AVN is necessary for optimal treatment, however, it is hard to take regular examination such as CT or MRI for detecting AVN. MRI is most sensitive to diagnosing osteonecrosis, but it is too expensive. We expect that tomosynthesis will not be a gold standard test but will be a useful tool for screening.PURPOSE: To evaluate the diagnostic performance of DTS in comparison with digital radiography in the detection of AVN of the femoral head with CT as the reference standard.MATERIALS AND METHODS: Forty-five consecutively enrolled patients (M:F = 24:21; mean age, 52.11 years; range, 25-77 years) underwent pelvic bone CT and DTS for evaluation of AVN. Radiography, DTS and CT were interpreted by two radiologists. AVN was classified into two types: one shows reactive interface showing linear sclerosis without fracture or collapse, and the other shows crescent sign or collapse. Receiver operating characteristic curve was used to compare the diagnostic performance of digital radiography with that of DTS. Intraobserver and interobserver reliability of readings was assessed with the intraclass correlation coefficient

(ICC) and Cohen kappa.RESULTS: Etiologies of AVN were as follows: systemic lupus erythematosus (n = 9), rheumatoid arthritis (n = 7), trauma (n = 7), osteoarthritis (n = 5), systemic sclerosis (n = 1), alcohol (n = 3), dermatomyositis (n = 1), unknown origin (n = 12). Eighteen patients had bilateral AVN on the femoral heads. Detection of sclerosis (AUC, 0.79 vs. 0.95, p = 0.011), crescent sign (AUC, 0.88 vs. 1.00, p < 0.001) and osteoarthritis (AUC, 0.85 vs. 0.95, p = 0.034) were significantly better with DTS than with digital radiography. Digital radiography and DTS showed excellent intraobserver agreement (ICC = 0.754-0.960, 0.840-0.994). Interobserver agreement were fair to almost perfect for digital radiography (ĸ = 0.167-0.881, p < 0.001), moderate to almost perfect for DTS (ĸ = 0.485-0.918, p < 0.001). The kappa values between radiography and CT showed moderate agreement (k = 0.41-0.51, p < 0.001), and the kappa value between DTS and CT showed almost perfect agreement value (k = 0.94-0.98, p < 0.001). CONCLUSION: DTS provides better diagnostic performance compared with digital radiography and similar diagnostic performance, lower cost and radiation compared with CT for evaluation of AVN.

SS 04 MS-05 10:30Reproducibility augmentation for pes planus assessment by deep learning-based algorithm in less-experienced physician: comparison between manual and algorithm-assisted measurements of Meary’s angleJalim Koo1, Sangchul Hwang1, Seung Hwan Han1, Sungjun Kim1, Joohee Lee1, Young Han Lee2, Jae ho Lee1, Jiae Choi1, Nari Shin1 1Gangnam Severance Hospital, 2Severance Hospital, Korea. [email protected]

PURPOSE: To ascertain whether deep learning-based algorithm augments reproducibility of Meary’s angle measurement in less-experienced physician by comparing inter- and intraobserver reproducibility between manual and deep learning (DL) algorithm-assisted measurements.MATERIALS AND METHODS: A total of 300 right and left weight-bearing lateral radiographs from 150 adult (> 18 years) patients, which were serially collected from August 2018 to September 2018, were split into training (n = 180), validation (n = 70), and test (n = 50) sets based on the obtained dates. A SegNet-based measurement tool was developed using training and validation data sets which were curated by two experienced radiologists. Using the test set, Meary’s angles were independently measured by two less-

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experienced resident trainees with algorithm-based tool and non-algorithm-based tools. The measurements were done twice for each tool with intervals between each measurement session being one-week. The points for measurements were automatically detected by the algorithm and the points were adjusted by the radiologists if being needed. Intraclass correlation coeff ic ient ( ICC) was calculated between the measurement in terms of inter-and intraobserver agreement. ICC comparison was done using z-test.RESULTS: ICC with algorithms for reader 1 and 2 were 0.897 (95% CI, 0.826-0.940) and 0.903 (95% CI, 0.836-0.944) respectively. ICC without algorithms for reader 1 and 2 were 0.543 (95% CI, 0.314-0.712) and 0.726 (95% CI, 0.563, 0.835), respectively. In both Reader 1 and Reader 2, ICC with algorithms were greater with statistical significance (p < 0.01). As for interobserver agreement, ICC for the first and second sessions without algorithm were 0.707 (95% CI, 0.535-0.822) and 0.661 (95% CI, 0.471-0.793). ICC for the first and second sessions with algorithm were 0.866 (95% CI, 0.775-0.922) and 0.900 (95% CI, 0.829-0.941), respectively. In both session 1 and 2, ICC with algorithms were greater with statistical significance (p < 0.05).CONCLUSION: Deep learning algorithm-tool augmented reproducibility of Meary’s angle measurement on weight-bearing lateral radiographs.CLINICAL RELEVANCE/APPLICATION: Deep learning algorithms are expected to elevate consistency of measurements to diagnose pes planus.

SS 04 MS-06 10:40Effect of supine and prone forefoot positions with or without silicone toe spacer on evaluation of MR anatomy of metatarsophalangeal jointSang Yong Lee1, Han a Lee2 1Soo Hospital, 2Jeonju Soo Hospital, Korea. [email protected]

PURPOSE: Morton’s neuroma, intermetatarsal bursitis and tear of plantar plate are known to be common clinical problems at the level of metatarsophalangeal joint (MPJ) of lesser toes. The correct diagnosis of these diseases is essential step for the determination of treatment plan. Clinical examination is important to diagnose, but ultrasonography or MRI of forefoot is commonly used for the confirmation. Recently prone position of forefoot for MRI is suggested for better diagnosis of Morton’s neuroma. We evaluated effect of supine or prone positions of forefoot with toe spacer or without toe spacer for MR anatomy of MPJ of lesser toes.MATERIALS AND METHODS: MRI of five young volunteers (mean age, 27 years) was obtained by using

proton-density weighted coronal MR sequence (TR/TE = 2820/28 ms, matrix = 300 × 261, FOV = 120 × 120 mm, slice thickness = 2 mm). MR images were obtained with (1) supine position without toe spacer and (2) with toe spacer, (3) prone position without toe spacer and (4) with toe spacer. We evaluated (1) lateral tilting of head of 2nd metatarsal bone, degree of visualization of (2) superficial transverse intermetatarsal ligament (STIL), (3) perforating fibers, (3) deep transverse intermetatarsal ligament (DTIL), (4) neurovascular bundle and (5) interosseous muscle tendon and collateral ligament of MP joint at the level of the head of metatarsal bone. Degree of visualization of anatomic structures was divided into four grades, 0 (fail), 1 (poor), 2 (fair) and 3 (good).RESULTS: Placement of toe spacer did not affect the MR evaluation of MPJ. Lateral tilting of head of metatarsal bone was less on MRI of prone position (25 degrees on supine, 10.5 on prone). Visualization of superficial and deep transverse intermetatarsal ligament and interosseous muscle tendons and collateral ligaments did not show significant differences between supine or prone position. However, perforating fibers was shown more clearly on MRI of prone position. Visualization of neurovascular bundle was shown to be better on MRI of prone position of forefoot.CONCLUSION: On MRI obtained with prone position head of metatarsal bone shows more vertically than that with supine position. MRI of prone position was helpful for the evaluation of neurovascular bundle which is structure involved in Morton’s neuroma. Perforating fibers, which surround the neurovascular bundle, between STIL and DTIL could be defined more clearly on MRI of prone position.

SS 04 MS-07 10:50Evaluation of articular cartilage of the glenohumeral joint in patients with labral tears using T2 mapping technique: is there a correlation between cartilage T2 values and location?Ayeon Kim, Eun Kyung Khil, Jung-Ah Choi Hallym University Dongtan Sacred Heart Hospital, Korea. [email protected]

MATERIALS AND METHODS: IRB approval was obtained and informed consent was obtained for this prospective study. From November 2016 to July 2018, we prospectively obtained and analyzed 30 unilateral shoulder MRIs with T2 mapping in patients with suspected labral tears. T2 values of cartilage were measured dividing the glenoid and humeral side into 9 areas as antero-superior, antero-central, antero-inferior, central-superior, central-central, central-inferior, postero-

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superior, postero-central, postero-inferior and measured twice by two radiologists. Intra- and interobserver agreements were calculated by using the intraclass correlation coefficient (ICC). Labral tears were classified according to location and extent as follows: SLAP II (variants included), SLAP V, VIII, inferior labral tear, circumferential labral tear. The correlation was analyzed using independent student T test and ANOVA test.RESULTS: Inter-observer agreement of MRI using T2 mapping value of cartilage was moderate (glenoid; 0.612, humerus; 0.530), intra-observer agreement was good (glenoid; 0.763, humerus; 0.866). Location and extent of labral tears showed a tendency to correlate with T2 values at glenoid cartilage although no statistically significant correlation was found. No significant association existed between the frequency of shoulder dislocation and T2 values of cartilage.CONCLUSION: Cartilage T2 values of glenohumeral joint cartilage showed good agreement regarding reproducibility; however, there was neither significant correlation with location and extent of labral tears and nor frequency of dislocation.

SS 04 MS-08 11:00Correlation between ultrasonographic, radiographic findings and pain scores in patients with osteoarthritis of knee jointAbhay Pratap Singh, Sonal Saran, Ravikant Kaushik, Surendra singh Subharti Medical College, India. [email protected]

PURPOSE: Pain and disability are predominant presenting features of knee osteoarthritis. Ultrasonography has evolved as one of the new imaging modalities in musculoskeletal imaging. This study aims to explore the correlation between ultrasonographic, radiographic findings and pain scores in patients with osteoarthritis of knee joint.MATERIALS AND METHODS: This descriptive study was carried out in the Department of Radiodiagnosis, Subharti Medical College, Meerut, India. Twenty-six consecutive patients with clinical osteoarthritis of the knee were included in the study. Knee pain was evaluated with the help of visual analog scale (VAS) and Western Ontario and Macmaster Universities Osteoarthritis Index (WOMAC) score. Conventional radiography was used to grade osteoarthritis by Kellgren and Lawrence (KL) system. Ultrasound criteria were the length of osteophytes, trochlear hyaline cartilage grading, presence or absence of meniscal protrusion, baker’s cyst and joint effusion. Ultrasonographic and radiographic assessment was performed by two different examiners blinded to the clinical results and to each

other.RESULTS: Among twenty-six patients (52 knees), male to female ratio was 7:19 with a mean age of 57.55 ± 8.48 years in females and 61.57 ± 10.43 years in males. The average duration of symptoms was 21.29 ± 18.94 months. The mean VAS score was 6.19 ± 1.79 and mean WOMAC score was 63.0 ± 13.77. The number of knees with a KL Grading score of 1, 2, 3, 4 were 3 (5.8%), 13 (25%), 13 (25%), 23 (44.2%) respectively which showed a significant positive correlation with VAS and WOMAC scores. The presence of medial meniscus extrusion (27 knees) and baker’s cyst (6 knees) showed a significant positive correlation with pain scores. The presence of lateral meniscus extrusion (21 knees) and effusion (20 knees) was associated with an increase in pain scores but a significant positive correlation was not seen. Higher grades of trochlear cartilage damage were associated with an increase in pain scores but a significant positive correlation was not seen.CONCLUSION: Our study found that conventional radiographic and few ultrasonographic criteria showed a significant positive correlation with pain scores of the knees. Both the modalities are complementary to each other, however, ultrasonography was able to demonstrate soft tissue pathologies better than radiography.


Recent Trend in MSK Imaging

Chairperson(s)Soo-Jung Choi GangNeung Asan Hospital, KoreaJi Seon Park Kyung Hee University Hospital, Korea

SS 31 MS-01 09:50Development and validation of deep learning based diagnosis algorithm for ankylosing spondylitis on CTYoung Kwang Lee1, Eun Hea Park1, Jin Hee You1, Myungjin Seol2, Yeong Sang Hong3, Gong Yong Jin1 1Chonbuk National University Hospital, 2Wonkwang University Hospital, 3Chosun University Hospital, Korea. [email protected]

PURPOSE: To develop and validate a diagnosis algorithm based on deep learning for Ankylosing Spondylitis on CT and check the performance by comparing to the experienced and inexperience radiologist.M AT E R I A L S A N D M E T H O D S : T h i s c l i n i c a l

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retrospective study used 681 SI joint CT image from 22 AS confirmed patient from ASAS guideline and 14 controls. A deep learning algorithm (DLA) based on a modified InceptionV3 architecture has been designed and tested, with one classifier produced simply by training and another produced by minimizing validation loss. Four radiologists composed of 2 musculoskeletal radiologists and 2 general radiologists reviewed CT image and checked erosion, sclerosis, and ankyloses. The sensitivity, specificity of DLA and radiologist was calculated.RESULTS: Our DLA achieves an 8-fold cross-validation accuracy and recall of 98.7% and 96.5%, respectively, for erosion vs. all control patient and the mean area under the curve (AUC) was 0.97. The sensitivity of musculoskeletal radiologist was 98.2% and the general radiologist was 88.1%.CONCLUSION: In differentiating between Ankylosing Spondylitis and normal patient including old age degeneration, the performance of DLA was comparable to the musculoskeletal radiologist and outperformed than the non-musculoskeletal radiologist.

SS 31 MS-02 10:00Automated quantitative assessment of normal attenuation muscle area and myosteatosis on CTDong Wook Kim1, Yousun Ko1, Kyung Won Kim1, Tae Yong Pak2, Yongbin Shin1, Ji Woo Lee1 1Asan Medical Center, 2Soongsil University, Korea. [email protected]

PURPOSE: To evaluate feasibility of automated quantitative measurement of skeletal muscle on CT for assessing normal attenuation muscle and myosteatosis.MATERIALS AND METHODS: Healthy subjects who underwent CT were retrospectively included and randomly selected to compose six different age groups from 20 s to 70 s. Automatic segmentation of total abdominal muscle area (TAMA), visceral fat area, and subcutaneous fat area was done using a pre-trained deep learning model on a single axial image at the inferior endplate level of L3 vertebra. By using an automated analysis function, the Hounsfield unit (HU) of each pixel in the TAMA was measured and categorized into three components, i.e., normal attenuation muscle area (NAMA; range, 30 to 150 HU), low attenuation muscle area (LAMA; range, -29 to 29 HU) representing muscle with excessive intra-myocellular fat deposit, and inter-muscular adipose tissue area (IMA; range, -190 to -30 HU). The TAMA and NAMA were divided by height squared to yield TAMA index and NAMA index. Area of myosteatosis was driven by adding the LAMA and IMA. With stratification by sex, these indices were compared between age groups using one-way analysis of

variance. Correlation between the area of myosteatosis, visceral fat, and subcutaneous fat was analyzed by using Pearson correlation.RESULTS: A total of 240 healthy subjects (135 males and 105 females) with 40 per age group were finally included. In the one-way analysis of variance, the NAMA, LAMA, IMA were significantly different between the age groups. The NAMA and NAMA index showed a gradual decrease with aging after a peak at 20 s in male and at 30 s in female, whereas no significant difference between age groups was noted in the TAMA and TAMA index in female (TAMA, p = 0.88; TAMA index, p = 0.10). The area of myosteatosis had moderate correlation with the visceral (r = 0.67 in male and 0.61 in female) and subcutaneous (r = 0.31 in male and 0.44 in female) fat areas.CONCLUSION: Quantitative CT assessment of normal attenuation muscle and myosteatosis might be better quantitative biomarkers for evaluating structural and functional changes in skeletal muscle with aging.CLINICAL RELEVANCE: The quantitative skeletal muscle mass assessment should consider intra- and inter-muscular fat, i.e., myosteatosis, and the normal attenuation muscle area might be the better biomarker of sarcopenia than total muscle area. We propose to use NAMA and myosteatosis area for future sarcopenia researches using CT.

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SS 31 MS-03 10:10Detection of rib fracture on chest radiographs using convolutional neural network (CNN)-based object detection modelJoohee Lee1, Youngno Yoon1, Daesung Kang2, Sungjun Kim1, Seungbo Lee1, Young Han Lee3, Sangchul Hwang1 1Gangnam Severance Hospital, 2Inje University,

3Severance Hospital, Korea. [email protected]

PURPOSE: To assess feasibility of convolutional neural network (CNN)-based object detection model in rib fracture detection on chest radiographs and to compare the performance among 3 detection models: RetinaNet, YOLO (You Only Look Once), and SSD (Single Shot Multibox Detector)MATERIALS AND METHODS: A total of 3809 chest radiographs were collected from 3167 patients from two hospitals between January 2011 and April 2018. The site of rib fracture was labeled by three experienced radiologists with consensus. We randomly separated the chest radiographs into training (3084/3809, 81%, 9413 fractures, 2596 patients), validation (381/3809, 10%, 923 fractures, 373 patients) and test (344/3809, 9%, 1215 fractures, 198 patients) sets. All images were resized to 512 by 512 or 1024 by 1024 pixels and randomly augmented in the deep learning network. We trained 4 networks for detecting rib fracture sites: RetinaNet resized to 1024 by 1024 pixels (RetinaNet_1024) and 512 by 512 pixels (RetinaNet_512), SSD resized to 512 by 512 pixels (SSD_512), YOLOv3 resized to 512 by 512 pixels (YOLO_512). With the proposed detections at each test images with the number of confidence and the coordinates, we calculated the value of mean Average Precision (mAP) which was used to evaluate the performance of network, and compared with their mAP values between three detection deep neural networks. Using the bootstrapping method, we calculated difference among the mAPs in 4 networks and sensitivity and positive predictive value (PPV) were compared using z statistics.RESULTS: RetinaNet_1024 achieved a higher mAP (0.53) than RetinaNet_512 (0.35), SSD_512 (0.28) and YOLO_512 (0.37). The sensitivity and PPV were 43.5% (528/1215) and 71.2% (528/742) for RetinaNet_1024, 16 .9% (205 /1215 ) and 83 .7% (205 /245 ) f o r RetinaNet_512, 7.5% (91/1215) and 92.9% (91/98) for SSD_512 and 8.1% (98/1215) and 96.1% (98/102) for YOLO_512, respectively, with a confidence threshold of 0.5.CONCLUSION: The Ret inaNet_1024 showed higher performance compared to the other object detection algorithms in detection of rib fracture on chest radiographs. Also, the resolution affected the

performance of RetinaNet.

SS 31 MS-04 10:20A preliminary study on deep learning-based automatic muscle segmentation of the thigh in CT imagesJi-Eun Kim, Ja-Young Choi, Hye Jin Yoo, Hee Dong Chae, Ji Hee Kang, Hyunjung Yeoh Seoul National University Hospital, Korea. [email protected]

PURPOSE: To develop and validate a deep learning-based automatic muscle segmentation of the thigh from the non-contrast CT images.MATERIALS AND METHODS: The clinical dataset consisted of 8226 images from 15 anonymized non-contrast thigh CT scans including both hip and knees. Manual drawing of three thigh muscle groups, i.e., anterior extensor (Class 1), medial adductor (Class 2), and posterior flexor (Class 3) group was performed on each axial image using the in-house developed software. In the preprocessing, left and right thighs were divided into separate images in order to increase the number of images and resampled to 512 × 512 while maintaining the image ratio. In each model of the three groups, a total of 5154 images were assigned for training set, and a total of 3072 images for test set. Deep learning was performed on three muscle groups using the Keras API (Application Programming Interface) based on the tensor flow in the Ubuntu system. Each learning model was based on DenseNET201+U-net architecture and trained with 16 batch sizes, 0.0001 learning rate and 1000 epochs, respectively.RESULTS: Average segmentation DSC score accuracy of each groups with 2.5D U-Net was 94.2%, 93.0%, 93.1% in class 1, 2, 3, respectively. As for using 2D U-Net, DSC score was 94.7%, 94.0%, 95.0%, respectively. Average sensitivity of each groups with 2.5D U-Net was 95.2%, 93.5%, 91.3% in class 1, 2, 3, respectively. As for using 2D U-Net, sensitivity was 94.3%, 94.5%, 93.7%, respectively.

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CONCLUSION: A deep learning-based automatic muscle segmentation of the thigh into three anterior extensor, medial adductor and posterior flexor groups was achieved. This method could be easily used for quantification of entire muscle volume for each functional group of the thigh. We expect that it can be used an indicator of sarcopenia as well as a more accurate preoperative factor to predict surgical outcome of the total knee arthroplasty.

SS 31 MS-05 10:30MRI in comparison to other imaging modalities and its correlation to clinical activity of ankylosing spondylitisLeela Chaudhary1, Mahesh Chaudhary2, Dinesh Chaudhary3 1Memorial Hermann Hospital, USA, 2BSM Medical University, Bangladesh, 3Hillcroft Physicians PA, USA. [email protected]

BACKGROUND: Di fferent imaging modal i t ies, particularly magnetic resonance imaging (MRI) have an important role in diagnosis and in making decisions about the treatment options of ankylosing spondylitis (AS). Disease activity is an important measure to determine the prognosis of AS.PURPOSE: 1. To evaluate different imaging techniques and show advantage of MRI in diagnosing sacroiliac joint (SIJ) involvement in ankylosing spondylitis. 2. To evaluate the disease activity by MRI.MATERIALS AND METHODS: 36 patients, with mean age 28.52, M:F = 8:1, having radiograph, computed tomography (CT) and MRI for the diagnosis of AS were selected for the first part of the study. Among 36 patients, 17 with normal radiograph were chosen for the second part of the study. The third part of the study was divided into two sections. The first section of the third part included 42 patients having MRI and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score, and the second section involved 56 patients having MRI with C - reactive protein (CRP) results. Grading of SIJ was done by New York criteria of sacroiliac joint (0-normal, I-rough articular surface in radiograph and CT/abnormal signal in cartilage, synovia, bone marrow in MRI, II- bone destruction/sclerosis, III- joint space involvement, IV- total ankylosis). These three modalities used were compared based on their grades of SIJ. Patients having BASDAI (≥ 4) or CRP (≥ 10 mg/l) were said to be clinically active whereas in MRI presence of bone marrow edema or contrast enhancement of synovia shows active disease. Activity of disease as depicted by MRI was correlated with the clinically active disease.RESULTS: In the first part of the study, 83.3% (n = 30) of 36 showed higher grades in MRI than in radiograph

and 66.7% (n = 24) of 36 showed higher grades compared to CT. In our second part of the study MRI and CT showed positive findings in 100% (n = 17) and 41.2% (n = 7) respectively whereas all radiographs (n = 17) showed no abnormality. In the third part of the study, MRI showed sensitivity of 81% and specificity of 66% compared to BASDAI, and sensitivity of 77% and specificity of 50% relative to CRP.CONCLUSION: After comparison to other imaging modalities, MRI can be used as a standard to diagnose AS and a specific predictor of disease activity as well due to presence of strong correlation with clinical activity parameters.

SS 31 MS-06 10:40A validation study of topology optimization-based trabecular bone reconstruction for accurate bone strength assessmentJung Jin Kim1, Young Han Lee3, Bong Ju Chun2, In gwun Jang2 1KEIMYUNG UNIVERSITY Department of Mechanic Automobile, 2Korea Advanced Institute of Science and Technology, 3Yonsei University College of Medicine, Korea. [email protected]

PURPOSE: High-resolution (HR) in vivo imaging for bone microstructure, which is indispensable for reliable bone strength assessment, is a clinically challenging task due to excessive radiation dose and long scan time. This study presents a novel topology optimization-based method that can reconstruct trabecular bone from routine CT scan data and validates a clinical feasibility of the proposed method using micro CT data.MATERIALS AND METHODS: A right proximal femur of a 64-age Korean male cadaver was scanned by a micro CT at a 78.125 × 78.125 × 78.125 μm3 resolution. Four volumes of the interest (VOIs) of a 5 × 5 × 5 mm3

cubic region were designated in the femoral head as the reference images. Micro-CT images for the VOIs were downscaled to achieve low-resolution (LR) images of a 625 × 625 × 625 μm3 resolution, which is close to a routine CT scan resolution. Then, the LR downscaled images was reconstructed to have the same resolution of the original CT scan data (i.e., reference images). Characteristic trabecular patterns, morphometric indices, and bone strength of the reconstructed HR images were compared with those of the reference images.RESULTS: The reconstructed HR images showed characteristic trabecular patterns observed in the femoral head. Morphometric indices (BV/TV, Tb.Th, Tb.Sp, Tb.N, SMI, and DA in this study) had a maximum of 3.8% deviation between the reference images and reconstructed HR images. Moreover, bone strength of

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the reconstructed trabecular bone showed a 9.8% error compared with that of the reference image.CONCLUSION: The proposed method successfully reconstructed trabecular bone in the femoral head from the LR downscaled images which resolution is similar with that of routine CT scan data. For validation, the reconstructed trabecular bone was compared with the reference images (micro-CT scan data) in terms of trabecular patterns, morphometric indices, and bone strength.

SS 31 MS-07 10:50 Are the advantages of 3D Image Sequences in Knee MRI time efficient?Ms Neha, Rajul Rastogi, Francis Randhawa Teerthanker Mahaveer Medical College and Research Center, India. [email protected]

INTRODUCTION: Knee joint is the most frequently evaluated joint by magnetic resonance imaging (MRI). Technological advancement in computer design, hardware & processing speed have enabled significant technological growth in MRI knee joint.Recently, in addition to conventional 2D imaging of knee joint, advanced 3D sequences are also available which can be done in less time including 3DT1W, 3DT2W, 3D-STIR & 3D-T2GRE image. In addition to multiple advantages offered by 3D sequences, reduced scan time helps in better imaging due to increased patient compliance especially in apprehensive & claustrophobic patients but also will help in increasing throughput in countries with high workload.With the objective of assessing the advantage of using 3D Knee imaging sequences in terms of scan time, we planned the following study to find out objectively the difference in scan time by using 2D & 3D image sequences in age & sex-matched controls.MATERIALS & METHODS: This study was carried out on a total of 100 cooperative patients (irritable and claustrophobic patients were excluded), 50 each for 2D and 3D sequence including both indoor & outdoor patients referred to MRI in the Department of Radiodiagnosis, Teerthanker Mahaveer Medical College & Research Centre Moradabad, Uttar Pradesh.All the patients were examined with 16 Channel Siemens Magnetom Avanto 1.5Tesla (Tim+Dot) MRI System with high-resolution knee coil.Usual protocol of knee MRI included T1W, T2W, STIR and T2GRE image sequences. For all of the above image sequences, 3D sequences are available.OBSERVATIONS AND RESULTS: The scan time for knee MRI with all 2D sequences ranged from 22-23 minutes while that for patients with 3D image sequences

was 18-19 minutes.Thus, the knee MRI scan time with available 3D image sequences offered to lower the scan time by nearly 20% allowing better time efficiency and throughput.CONCLUSION: Our study objectively proves that utilising available 3D image sequences during routine knee MRI imaging not only offer many advantages while overcoming many disadvantages of 2D image sequences but also helps in improving patient throughput by reducing scan time significantly. Reduced scan time is translated in to improved healthcare by reducing patient waiting time and improved business thus sustaining healthcare infrastructure including human resource.

SS 31 MS-08 11:00UTE for evaluating osseous erosion in SIJ MRI of SpA - comparison of conventional MRI and 3D isotropic proton densityMyungjin Seol1, Eun Hea Park2, Seon-Kwan Juhng1, Jin Hee You2, Young sang Hong3, Youngkwang Lee2, Dong han Shin2 1Wonkwang University Hospital, 2Chonbuk National University Hospital, 3Chosun University Hospital, Korea. [email protected]

PURPOSE: To determine the availability of an ultrashort TE (UTE) sequence for the evaluation of erosion in sacroiliac joint magnetic resonance imaging (MRI) compared with conventional T1-weighted (T1WI) and 3D isotropic proton density (3DPD).MATERIALS AND METHODS: Thirteen spondyloarthropathy (SpA)-diagnosed patients based on ASAS criteria who underwent MRI including T1WI, 3DPD and UTE were enrolled in this study. Three radiologists (2 musculoskeletal and 1 resident) reviewed T1WI, 3DPD, and UTE sequences and 1) assessed osseous erosion (4 point scale, right and left side) and 2) scored image quality in diagnosis of erosion based on anatomic sharpness (4 point scale, right and left side). Patients were divided into mild erosion (group A) and advanced erosion (group B).RESULTS: In group A, UTE was significantly better detecting erosion compared with other 2 sequences for all 3 readers (UTE vs. 3DPD vs. T1WI = 3.5 vs. 2.7 vs. 2.5, respectively, p < 0.05). With respect to anatomic sharpness, UTE showed a significantly higher score for the resident: UTE = 5.1, 3DPD = 4.7, T1WI = 3.3. In group B, there was no significant difference between the 3 sequences for the MSK radiologist, but for the resident, UTE yielded a higher score for detecting erosion (UTE vs. 3DPD vs. T1WI = 4.2 vs. 3.6 vs. 3.6, respectively, p < 0.05). Although the difference did not

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Musculoskeletal (SP) Sep 19, Thu

reach statistical significance, image quality showed a higher score with UTE and 3D compared with T1WI for all 3 readers.CONCLUSION: Choice #1: UTE yielded better detection of osseous erosion compared with 3DPD or T1WI when erosion was mild and showed improved anatomic sharpness. For those with advanced erosion, UTE, 3DPD, and T1WI all demonstrated erosion well. UTE is expected to aid better diagnosis in early SpA, especially for young radiologists. Choice #2: while T1WI and 3DPD can demonstrate osseous erosion well in advanced cases, the UTE sequence yielded better detection of erosion even in mild cases. UTE is expected to aid better diagnosis in early SpA, especially for young radiologists.CLINICAL RELEVANCE: Lately bone marrow edema is reported to be found even in nonSpA cases, allowing early detection of subtle erosion to be important factor in diagnosis of early SpA. UTE sequences of MRI can demonstrate an osseous structure well and are expected to aid better diagnosis of early SpA.

SS 31 MS-09 11:10 Spondyloarthropathy: improved diagnostic performance by combining UTE with conventional MRIYeong Sang Hong1, Donghun Kim1, Eun Hea Park2, Myungjin Seol3, Youngkwang Lee2, Donghan Shin2 1Chosun University Hospital, 2Chonbuk National University Hospital, 3Wonkwang University Hospital, Korea. [email protected]

PURPOSE: To evaluate whether the combination of ultrashort TE (UTE) sequences and conventional magnet ic resonance imag ing (MRI ) he lps to increase diagnostic performance in the diagnosis of spondyloarthropathy compared with those achieved by using each MRI technique alone.MATERIALS AND METHODS: The study included 28 sacroiliac joint (SIJ) MRI from 14 spondyloarthropathy (SpA) patients and 18 SIJ MRI from 9 patients without SpA. Patients were classified according to rheumatologist expert opinion. Four sets of MRI sequences (T1, CE T1FS, T2FS, and UTE) were assessed independently by two MSK radiologists for bone marrow edema on FS T2WI, enhancement on contrast enhanced FS T1WI, and erosion on each T1WI and UTE. On UTE image, erosion was subdivided based on depth. Diagnostic accuracy, sensitivity, and specificity were calculated.RESULTS: The overall diagnostic accuracy and sensitivity were significantly higher for the combined set (89.1% and 100%) of UTE and conventional MRI

than those for the conventional MRI-only (76.1% and 82.1%) or UTE-only (87.0% and 96.4%) sets. However, specificity was relatively low in combined set (72.2%) as well as UTE/conventional only sets (72.2%/66.7%). Subdivided by depth of erosion on UTE, the specificity was markedly increased (100%) without significant decreasing the accuracy (91.3%) and sensitivity (85.7%). Regarding the detection of erosion, readers showed high diagnostic confidence on UTE (2.65) compared with T1WI (1.97).CONCLUSION: UTE provides CT-like images, allowing good depiction of erosion; a combination set of UTE and conventional MRI show better diagnostic performance and confidence in the diagnosis of SpA.CLINICAL RELEVANCE: Recently, BME of the SIJ are reported to be nonspecific findings in SIJ MRI, leaving osseous erosion to be important finding. With UTE providing CT-like imaging, this will help detect early erosion, resulting better diagnosis of SpA.

Musculoskeletal(SP) 09:40 - 11:10 Grand Ballroom 102

Spine Imaging and Interventions

Chairperson(s)Sun Joo Lee Inje University Busan Paik Hospital, KoreaSung Gyu Moon Konkuk University School of Medicine,

Korea

SS 13 MS(SP)-01 09:40Prognostic prediction in initially diagnosed multiple myeloma patients using IVIM-DWI and multi-echo Dixon MR imagingAram Jo1, Joon-Yong Jung1, Hyerim Park1, Seung Eun Lee2 1The Catholic University of Korea, Seoul St. Mary’s Hospital, 2The Catholic University of Korea, Yeouido St. Mary’s Hospital, Korea. [email protected]

PURPOSE: To evaluate the feasibility of the multi-parametric MRI including intravoxel incoherent motion-diffusion-weighted imaging (IVIM-DWI) and multi-echo Dixon on prediction of the prognosis in initially diagnosed multiple myeloma (MM).MATERIALS AND METHODS: This retrospective study included forty-six patients (M:F = 29:17; mean age, 60.4 years), who initially diagnosed as MM in our institution. All patients underwent complete set of laboratory work-up and received MRI of lumbar spines, including IVIM-DWI and multi-echo Dixon prior to

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initiation of the therapy. The freehand region of interest (ROI) was drawn within the marrow space of vertebral body on a single axial parametric maps: pure diffusion coefficient (Dslow), pseudodiffusion coefficient (Dfast) and perfusion fraction (Pf) maps from IVIM-DWI, and proton-density fat-fraction (PDFF) maps from multi-echo Dixon MR imaging. The good and poor prognosis groups were defined by multiple myeloma international staging system (ISS). The measured values were compared between good prognostic group (ISS-1) and poor prognostic group (ISS-2&3). A logistic regression model was built to predict the prognosis.RESULTS: Among these 46 patients, 32 were ISS-1, and 14 were ISS-2&3. Dslow of ISS-1was significantly lower than that of ISS-2&3 (0.37 × 10-3 vs. 0.56 × 10-3 mm2/s, p < 0.01). PDFF of ISS-1 was significantly higher than that of ISS-2&3 (0.55 vs. 0.22, p < 0.001). In contrast, there was no difference in Pf and Dfast between ISS-1 and ISS-2&3 (p = 0.389, p = 0.544, respectively). The regression model using Dslow and PDFF as independent variables predict prognosis with an accuracy of 43.8%. The area under receiver-operating characteristic curve (AUC) value of the regression model was 0.93 ± 0.049.CONCLUSION: Dslow from IVIM-DWI and PDFF from multi-echo Dixon were significantly associated with the prognosis in initially diagnosed MM.CLINICAL RELEVANCE: Multiparametric bone marrow imaging with IVIM-DWI and multi-echo Dixon could be used to predict the prognosis in initially diagnosed MM.

SS 13 MS(SP)-02 09:50 A semantic segmentation and separation with cascaded 3D U-Net to compare performances of normal controls and patients in cervical spine CTKeewon Shin1, Younghwa Byeon1, Seong Yi2, Sung-Uk Kuh3, Jin S. Yeom4, Namkug Kim1 1Asan Medical Center, 2Severance Hospital, 3Gangnam Severance Hospital, 4Seoul National University Bundang Hospital, Korea. [email protected]

PURPOSE: Segmentation of cervical vertebrae in CT is an essential but tedious and time-consuming task for radiologists. Moreover, a fully automated segmentation is much more difficult due to disease variations, thin bone thickness, and partial volume effects. In this paper, we propose a fully automated method of C-spine segmentation and separation in CT images and to see

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how the normal and abnormal patients dataset affect the segmentation performance.MATERIALS AND METHODS: 17 patients with spine diseases (contained HCD, CSM, C-OPLL, Stenosis) from Severance/Gangnam Severance Hospitals (S/GSH) and 40 healthy controls from Seoul National University Bundang Hospital (SNUBH) were scanned by using volumetric CT protocols. To prepare gold standard labels, each spine was segmented by using conventional image-processing methods and manually corrected by an expert. Semantic segmentation was evaluated as follows: firstly, a combined dataset was used to verify the segmentation performance of the cascaded 3D U-Net model with 5-fold cross-validation. Secondly, the model of training disease dataset was extra-validated with healthy control dataset, and vice versa. The evaluation metrics are the Dice similarity coefficient (DSC) and mean surface distance (MSD).RESULTS: 3D segmentation of the cervical spine showed high performance of DSC 95.20.27%, MSD 0.080.03 mm in the combined dataset from multi-centers. The mean and standard deviation of the DSC and MSD in intra-dataset (S/GSH, patients) and extra-dataset (SNUBH, normal control) were 92.25.82%, 0.090.03 mm and 88.74.94%, 0.240.17 mm and in vice versa, 92.16.07%, 0.240.12 mm and 65.418.50%, 4.352.45 mm respectively. When comparing the performance of training each normal and the disease patients dataset, the test performance was better when learning patient dataset even though the number of the disease group is smaller.CONCLUSION: We have deve loped the fu l ly automated segmentation and separation model on cervical vertebrae in CT using cascade 3D U-Net, which demonstrated high performance. In addition, it is important to train various diseases dataset to improve the performance of C-spine segmentation.

SS 13 MS(SP)-03 10:00Evaluation of the potential diagnostic value of the scout images on lumbar spine MRI Ja Yeon You1, Joon Woo Lee2, Jiwoon Seo3, Jee Won Chai4, Hee Dong Chae5, Heung Sik Kang2, Sung Hwan Hong5 1S&K Hospital, 2Seoul National University Bundang Hospital, 3Catholic Kwandong University International St. Mary’s Hospital, 4SMG-SNU Boramae Medical Center, 5Seoul National University Hospital, Korea. [email protected]

PURPOSE: To evaluate the diagnostic value of the scout images for the extra-spinal organs in lumbar spine MRI and investigate the difference of diagnostic performance according the scout image protocols.

MATERIALS AND METHODS: A total of 150 patients (M:F = 72:78; mean age, 59.4 ± 16.9 years; range, 18-86 years), who underwent 1.5T or 3T lumbar spine MRI from March to September 2015 at three hospitals (A, B, and C) having different scout image protocols, were selected. Two radiologists were retrospectively and independently reviewed scout images to investigate whether major diseases can be exclusively diagnosed in the femoral head, femoral neck, sacroiliac joint, and kidney. The diagnostic confidence level was divided to 4 categories: definitely, possibly, limited, and non-evaluable. Definitely and possibly evaluable cases were designated to the positive cases. Interobserver reliability was analyzed. The difference of diagnostic confidence level was compared according to the image protocols.RESULTS: Of 150 patients, 50-62 (33.3-41.3%), 37-66 (24.7-44.0%), 72-93 (48.0-62.0%), and 63-73 (42.0-48.7%) cases were classified in the definitely evaluable cases for the femoral head (κ = 0.63-0.71), femoral neck (κ = 0.41-0.48), sacroiliac joint (κ = 0.35-0.37), and kidney (κ = 0.45-0.47) by two readers, respectively. More than 50% cases of femoral head, sacroiliac joint, and kidney were classified in positive cases. Among them, excellent interobserver agreement was shown for the femoral head (κ = 0.92-0.93). According subgroup analysis, the number of positive cases in the femoral head was higher on gradient-proton density weighted image than gradient- T2* weighted image (p ≤ 0.007). The percentage of positive cases in both femoral head and neck was higher on hospital C (7 slices of coronal plane) than hospital A (3 slices of coronal plane) (p ≤ 0.015).CONCLUSION: The scout image in lumbar spine MRI is sufficiently readable to exclusively diagnose some major diseases in the extra-spinal organs. Consequently, scout image should not be ignored on routine practice.

SS 13 MS(SP)-04 10:10Intraarticular facet joint steroid injection related adverse events encountered during 11,980 procedures performed at a single centerBo Ram Kim, Joon Woo Lee, Eugene Lee Seoul National University Bundang Hospital, Korea. [email protected]

PURPOSE: To analyze incidence and characteristics of intraarticular facet joint injection (FJI) related adverse events requiring hospitalization and emergency room visits.MATERIALS AND METHODS: From January 2007 to January 2017, total 11,980 FJI procedures in 6066 patients (mean age, 66.8 years; range, 15-97 years; M:F = 2004:4062) were performed in our department. Of these, we retrospectively reviewed 489 cases in 432



patients who were hospitalized or visited the emergency room within a month of FJI. Cases other than hospitalization or ER visit that are not definitely related FJI, were regarded as FJI related adverse events. FJI related adverse events were classified as procedure related complications, drug related systemic events or uncertain etiology events, on the basis of consensus of the two spine radiologists. This is descriptive study without statistical analysis.RESULTS: There were 105 FJI related adverse event cases in 103 patients (mean age, 71.8 years; range, 39-97 years; M:F = 41:62). The overall incidence of FJI-related adverse was 0.88% (105/11980) per case and 1.73% (105/6066) per patient. The incidence of procedure related complications was 0.08% (9/11980); drug related systemic adverse events was 0.18% (21/11980) and uncertain etiology events was 0.63% (75/11980). All nine cases of procedure related complications were major complications. Seven cases were infectious spondylitis, one was cellulitis in other site and one was progression of systemic aspergillosis to spine. One patient died of an uncontrollable infection with infective endocarditis and two patients experienced partial recovery with neurological sequelae.CONCLUSION: Overall incidence of FJI related adverse event is low and procedure related major complications are rare. However, major complications can occur and result in serious outcome. FJI should be carefully decided and administered after confirming patient’s medical history and risk factors.

SS 13 MS(SP)-05 10:20 Efficacy of epidural steroid injection in patients with lumbar herniated intervertebral disc under a “wait-and-see” policyBo Ram Kim, Joon Woo Lee, Eugene Lee, Yusuhn Kang, Joong Mo Ahn, Heung Sik Kang Seoul National University Bundang Hospital, Korea. [email protected]

BACKGROUND: There are no consensus and guidelines on optimal timing and interval of repeat epidural steroid injections (ESIs) for patients with lumbar herniated intervertebral disc (HIVD) who respond to initial ESI. Decision to repeat ESI is solely based on clinician’s experience and preference and on patient demand.PURPOSE: To evaluate the efficacy of ESIs in patients with lumbar HIVD under a “wait-and-see” policy, i.e., as-needed injections not on a predetermined schedule.MATERIALS AND METHODS: This study was approved by the Institutional Review Board, and the requirement for informed consent was waived. Five hundred and ninety-two patients with lumbar HIVD

received spine injection from January 2017 to December 2017 in our department. After excluding patients with excellent response (no pain) or poor response (over 70% of residual symptoms) in the 2 or 3-week pain assessment, the data of 141 responders were analyzed (M:F = 60:73; age, 50.55 ± 17.25 years). We divided patients into two groups: a wait-and-see group (n = 124) and an early repeat-ESI group (n = 17), who received repeat ESI within 3 weeks. Evaluations of characteristics and outcomes were performed with the chi-squared test or independent Student’s t-test.RESULTS: Six patients (4.8%) in the wait-and-see group and one patient (5.9%) in the early repeat-ESI group underwent operation within 1 year (p = 0.853). A mean of 1.52 ± 0.82 ESIs was performed in the wait-and-see group and a mean of 2.29 ± 0.47 in the early repeat-ESI group during the follow-up period (p < 0.001). Seventy-eight patients (62.9%) in the wait-and-see group could control their pain with a single ESI, although one underwent surgery at another hospital. The time interval between the first and second ESIs (97.15 vs. 15.47 days, p < 0.001) was longer in the wait-and-see than in the early repeat-ESI group.CONCLUSION: A “wait-and-see” policy could be an effective pain management option for patients with lumbar HIVD who respond to initial ESI.

SS 13 MS(SP)-06 10:30The success rate and efficacy of fluoroscopy-guided synovial cyst rupture with intra-articular steroid injection, at the lumbar facet of post-laminectomy levelHyo Jin Kim1, Eugene Lee2, Joon Woo Lee2 1SMG-SNU Boramae Medical Center, 2Seoul National University Bundang Hospital, Korea. [email protected]

In this study, we reviewed the success rate and efficacy of fluoroscopy-guided synovial cyst rupture with intra-articular steroid injection, at the lumbar facet of post-laminectomy level.Retrospectively from 2008 to 2017, in our tertiary hospital, we chose patients who underwent fluoroscopy-guided synovial cyst rupture with facet joint steroid injection at previous lumbar laminectomy levels (the presence of cysts had been proven by MR before the procedure and the location of the cysts was matched the patients’ symptom). We reviewed whether cyst rupture and symptom improvement was achieved by the procedure. The degree of symptom improvement was divided into four categories; ‘improved’, ‘not improved’, ‘underwent operation after the procedure’, and ‘follow-up loss’. We also checked relationship between the success of cyst rupture and imaging findings of the cysts

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(internal signal intensity, maximal diameter and wall thickness).Total 14 patients and 15 synovial cysts were included. Cyst rupture was successful in 10 cysts (66.7%) at the first procedure. 13 patients (92.9%) were categorized as ‘symptom improved’ and the other one underwent operation after the first procedure. Seven (53.8%) experienced re-procedure due to recurred symptom, and cyst rupture was successful in two (28.6%). Five (71.4%) were ‘symptom improved’, one was ‘symptom not improved’ and the other one was ‘follow-up loss’ after the second procedure. Among ‘symptom improved’, three experienced third procedure and cyst rupture was successful in one (33.3%). All three (100%) were ‘symptom improved’ after the third procedure. These three underwent fourth procedure and cyst rupture was successful in none. One was ‘symptom improved’, another one underwent operation, and the other one was ‘follow-up loss’. There was no significant relationship between the success of cyst rupture and imaging findings of cysts. Mean total follow-up period was 823.14 days.In summary, although the success rate of percutaneous synovial cyst rupture decreased as procedures were repeated, by fourth procedure over 71% patients experienced symptom improvement. Operation rate was 14%.Therefore for symptomatic lumbar facet joint synovial cysts at post-laminectomy levels, fluoroscopy-guided cyst rupture with intra-articular steroid injection can be effective management.

SS 13 MS(SP)-07 10:40 Feasibility of MR-generated synthetic CT images at cervical spine: diagnostic performance for detection of OPLL and Comparison of CT numberChankue Park, Hee Seok Jeong Pusan National University Yangsan Hospital, Korea. [email protected]

PURPOSE: To determine the incremental value of MR-generated synthetic CT (MRCT) for evaluation of cervical ossification of posterior longitudinal ligament (OPLL) and compare the CT number (Hounsfield unit, HU) between MRCT and conventional CT (CT).MATERIALS AND METHODS: Twenty two patients (mean age, 60 year; M:F = 13:9) who underwent MRCT protocol and CT within 1 month between August 2018 and February 2019 were enrolled. MRCT protocol consisted of 3D T2WI, PETRA, T1 VIBE Dixon, and TOF sequences. MRCT images were generated from MRCT protocol sequences using frontier program. Two readers independently evaluated the presence of OPLL at each cervical spine level (C1-2, C3, C4, C5, C6, and C7)

during session 1 (conventional MRI only, T1- and T2-WI) and session 2 (addition of MRCT to conventional MRI). CT was the reference standard for presence of OPLL. One reader measured HU value of vertebral body and posterior element of each cervical spine at MRCT and CT images.RESULTS: The sensitivity, specificity, diagnostic accuracy, positive predictive value, and negative predictive value during session 1 were as followed: reader 1 - 47%, 98%, 86%, 88%, and 86% and reader 2 - 63%, 94%, 87%, 76%, and 90%. Session 2 results were as followed: reader 1 - 90%, 89%, 89%, 71%, and 97% and reader 2 - 93%, 84%, 86%, 64%, and 98%. Inter-reader agreement was moderate (ĸ = 0.45) during session 1 and good (ĸ = 0.62) during session 2. Mean HU value between MRCT and CT shows moderate positive correlation (ρ = 0.58, p < 0.001).CONCLUSION: The combined analysis of MRCT and MRI improves sensitivity and negative predictive value on evaluation of cervical OPLL. Mean HU value between MRCT and CT shows moderate positive correlation.CLINICAL RELEVANCE: MR-generated synthetic CT images showing potential applicability for routine clinical practice.

SS 13 MS(SP)-08 10:50Visual and quantitative assessment on the annulus fibrosus in intervertebral disk degeneration with gradient echo phase imagingHyerim Park, Joon-Yong Jung, Yoonho Nam The Catholic University of Korea, Seoul St. Mary’s Hospital, Korea. [email protected]

PURPOSE: To demonstrate the potential application of phase image in the assessment of annulus fibrosus (AF) in the intervertebral disk degeneration (IDD).MATERIALS AND METHODS: Ex vivo intervertebral disk (IVD) sample from goat were scanned at 9.4T animal MRI using multiecho gradient echo (GRE) imaging (echo time = 7.5/12.5/17.5 ms) with two different orientations (perpendicular to B0 field and parallel with B0 field). The multiecho phase images were processed with Homodyne filtering to remove background phase, and normalized by echo time. Seventy-two axial images of intervertebral disk from 30 patients who underwent MRI of L-spines including multiecho GRE were processed and analyzed in this study. Phase image and corresponding R2* images are generated from multiecho GRE. For visual assessment, 3 independent readers analyzed AF-Nucleus purposus (NP) differentiation on phase images with 4-scale grading system. The visual grading were validated using rank correlation coefficient between phase image-based grading and Pfirrmann



grading, and interobserver agreements (weighted κ) among three readers. For quantitative analysis, phase and R2* values were measured at outer AF, and compared those values between mild, moderate and severe IDD groups using one-way ANOVA.RESULTS: Ex vivo sample demonstrated B0 orientation dependent phase contrasts between the AF regions and other regions, and direct correlation between the lamellar structures in the AF regions and the phase contrasts. Correlation between Pfirrmann grade and visual grading of NP-AF differentiation shows strongly positive (ρ = 0.813). Interobserver agreements (weighted κ) were substantial to nearly perfect: 0.841 (reader 1-2), 0.686 (reader 2-3) and 0.803 (reader 1-3). Average phase values in AF were -8.1 ± 5.25 (standard deviation), -4.9 ± 2.37 and -3.2 ± 3.64 in mild, moderate and severe IVD degeneration groups. There were significantly different between mild and moderate (p < 0.001), and mild and severe (p < 0.001) IDD groups. Whereas there was no difference in R2* values between groups: 61 ± 27.6 (mean ± standard deviation) in mild, 69 ± 23.5 in moderate, and 67 ± 19.7 in severe IDD.CONCLUSION: We demonstrated the potential of GRE phase imaging for assessment of AF in IVD. Visual grading of NP-AF differentiation using phase image could provide reliable indicator of IDD.

SS 13 MS(SP)-09 11:00Risk prediction of new vertebral compression fractions (VCF) following percutaneous vertebroplasty (PVP) in old women after menopause with osteoporotic vertebral compression fractures (OVCFs) Jiaying Zhou, Shenghong Ju Zhongda Hospital, Medical School, Southeast University, Nanjing, China. [email protected]

PURPOSE: To determine the risk predictors of new vertebral compression fractions following percutaneous vertebroplasty (PVP) in old women after menopause with osteoporotic vertebral compression fractures (OVCFs) and build the risk prediction model.MATERIALS AND METHODS: We retrospectively c o l l e c t e d t h e c l i n i c a l a n d i m a g i n g d a t a o f postmenopausal old women patients who are diagnosed with OVCF and treated with PVP between January 2008 and December 2016 in Zhongda Hospital Southeast University. The patients between January 2008 and December 2013 were grouped into the training cohort. The remainder were grouped into validation cohorts. Every patients were examined with computer tomography (CT) and magnetic resonance imaging (MRI) before treatment to be diagnosed with

OVCF. 3 days after PVP, all patients need to review the CT. In the training cohort, we use the Kaplan-Meier analysis and the Cox proportional hazard regression analysis to identify the risk predictors of the new VCF following PVP. Finally, we create the nomogram to show the visualization of the short-term and long- term probability of new VCF according to these risk factors. The accuracy of the model was validated internally and externally using the training and validation cohorts respectively.RESULTS: We enrolled 325 patients (training cohort: n = 196, validation cohort: n = 129) and 441 vertebras (training cohort: n = 274, validation cohort: n = 167). In training cohort, there were 64 patients who suffered from the new VCF following the first PVP (32.7%). After univariate and multivariate analysis, the fracture severity (p = 0.001), the number of vertebra involved (p = 0.001), the intradiscal cement leakage (p = 0.001), the history of fracture (p = 0.001), the age group (p < 0.001), hypertension (p = 0.007) and the average CT value of vertebra (p < 0.001) are identified as the risk factors of new VCF (p < 0.05). The c statistic of the model was 0.82 in the training cohort and 0.76 in the validation cohort. The new VCF 1 months, 1 year and 2 years after PVP would not happen, when patients have no risk factors. But when having the all risk factors, the short-term probabilities of new VCF were over 80%.CONCLUSION: More advanced age, hypertension, history of fracture, greater fracture severity, a greater number of vertebra involved, intradiscal cement leakage and a smaller CT value of adjacent vertebra are the independent risk factors of new vertebral fractions after PVP. The nomogram is helpful to predict the short-term and long-term probability of the new VCF after PVP.

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