Anatomy of the Lower Extremityin Computed Tomography

Michael C. Ficorelli, RT

Lesson Description

To explain the various exams pertaining to the lower extremity using computed tomography, incorporating cross sectional anatomy from images

Lesson Description

• To be able to identify anatomy of the lower extremity. Understand the clinical indications for exams of the abdomen. To understand the methods of patient scanning, positioning, and protocols. To understand indications for contrast.

CT of the Lower Extremity(Hip, Knee, Ankle, Foot)

Ankle and Foot Bony Anatomy• 7 Tarsal Bones

– Talus – responsible with the calcaneus for bearing weight; wedge shaped body with upper surface (trochlea) which articulates with Tibia and Fibula

– Calcaneus – Largest tarsal, prominence of the heel, tuberosity which is insertion for ligaments and tendons (Achilles)

• Sustentaculum Tali – medial surface which supports the talus• Sinus Tarsi – canal from articulation between talus and calcaneous

– Navicular, Cuboid, Lateral Cuneiform, Intermediate Cuneiform, Medial Cuneiform

• 5 Metatarsals• 14 phalanges – 3 for each toe except hallux (2)• Distal Tibia – Medial malleoli• Distal Fibula – Lateral malleoli

Ankle and Foot Anatomy

• Arches:– Longitudinal arch: Two parts – lateral and medial

– Provides firm base for support– Transverse arch: Distal row of tarsals (Cuboid, 3

cuneiforms) and bases of metatarsals creating dome – major weight bearing arch

• Important:– Retinacula – sheaths of tendons around the ankle– Fascia – thickened area on plantar surface

Foot Anatomy

Foot Anatomy

Ankle Joint

Knee Bony Anatomy

• Made up of:– Distal Femur – lateral and medial condyle and epicondyle

• Smooth anterior surface for articulation with the patella• Posterior - intercondylar fossa• Adductor tubercle – above medial epicondyle attachment for adductor

magnus– Tibia – widened proximal end with medial and lateral condyles

• Tibial Plateau – widened medial and lateral surfaces for articulation with femur

• Intercondylar eminence (Tibial Spine) – between the plateaus with two peaks (tubercles)

• Tibial Tuberosity – site of attachment of patellar ligament anteriorly– Fibula – long thin bone

• Head – apex, sharp and superior with surface that articulates with the lateral condyle of the tibia

Knee Anatomy• Patella

– Largest sesamoid in the body– Flat triangular bone with base proximal and apex distal

• Joint – 2 separate articulations – Femorotibia and Patellofemoral– Capsule – strong, fibrous membrane reinforced by extracapsular

ligaments• Anteriorly blends with quadriceps tendon

– Synovial membrane is largest synovial cavity of the body– Menisci – (2) found between femoral condyles, connective tissue

• Medial – attached to MCL, less mobile• Lateral – closed ring

– Ligaments – External and Internal• External – MCL, Lateral Collateral, Patellar• Internal – ACL, PCL

GROSS KNEE ANATOMY

KNEE ANATOMY

KNEE ANATOMY

KNEE ANATOMY

KNEE ANATOMY

KNEE ANATOMY

Ankle / Foot Protocol

• Lung nodules• Cancer• Vascular disease• Effusion and infiltration• Trauma• Pulmonary Parenchymal diseases• Hilar Masses

Parameters Single Slice 4 SLICE 16 SLICE

PATIENT FEET FIRST. SUPINE SAME SAME

SCANNING AREA

DEPENDS ON WHAT PART

SAME SAME

CONTRAST 100ML AT 1-2ML/SEC SAME SAME

DETECTOR COLLI NA 0.5MM 16X0.75

DFOV 14-18 SAME SAME

SLICE THICKNESS 16-20 MM SAME SAME

ANGLE NONE SAME SAME

TABLE FEED/ROT 3MM VARIES VARIES

PITCH 1 VARIES VARIES

ROT TIME 1 -2 SEC 0.75 SEC 1.5SEC

RECON STANDARD/BONE SAME SAME

WINDOW 450W/30L—2000W/200L

SAME SAME

Coronal Foot

1 – Calcanous2 – Talus3 – Navicular4 – Medial Cuneiform5 – Base of 1st MT6 – 2nd MT7 – 2nd Prox Phalanx8 – 2nd Middle Phalanx9 – 2nd Distal Phalanx10 – 5th MTP Joint11- Navicular

Coronal Foot

1 – Base of 5th MT2 – Cuboid3 – Calcaneus4 – Navicular5 – Medial Cuneiform6 – 1st MT7 – 1st Prox Phalanyx8 – 1st Distal Phalanyx9 – 2nd Middle Phalanyx10 – 4th MT Head

AXIAL ANKLE

1

2 1- Fibula

2- Tibia

AXIAL

12 3

1- Lateral malleolus

2- Tallus

3- Medical malleolus

AXIAL

1

2

3

1- Talus

2- CALCANUS

3- NAVICULAR

AXIAL

1

2

1- CUNEIFORM BONES

2- CUBOID BONE

SAGITAL MPR

12

3

4

5

6

1- TALUS

2- SINUS TARUS

3- CALCANEUS

4- CUBOID

5- CUNEIFORM

6- NAVICULAR

CORONAL MPR

1

2

3

4

5

1- LATERAL MALLEOLUS

2- TALAR JOINT

3- MEDICAL MALLEOLUS

4- TALLUS

5- CALCANEOUS

CORONAL MPR

1

1- Calcaneous

BONE VS SOFT TISSUE

BONE SOFT TISSUE

KNEE

1

1- FEMUR

KNEE

1

2

3

4

1- Medial condyle

2- Patella

3- Lateral condyle

4- intercondylar fossa

KNEE

1

1- Tibial Plataeu

KNEE1

2

1-Tibia

2- Head of fibula

CORONAL KNEE

1

2

3

1- Intercondylar fossa

2- Tibial plateau

3- Condyle of femur

PROTOCOL FOR HIP AND BONY PELVIS

• Lung nodules• Cancer• Vascular disease• Effusion and infiltration• Trauma• Pulmonary Parenchymal diseases• Hilar Masses

Parameters Single Slice 4 SLICE 16 SLICE

PATIENT FEET FIRST. SUPINE SAME SAME

SCANNING AREA CREST TO PUBISABOVE JOINT TO BELOW LESSER TUBEROSITY

SAME SAME

CONTRAST 100ML AT 2ML/SEC @ 30 SECOND DELAY

SAME SAME

DETECTOR COLLI NA 4 X 1MM 16 X 0.75

DFOV DEPENDS ON PATIENT FOR PELVIS/ 20 CM FOR HIP

SAME SAME

SLICE THICKNESS 5 MM SAME SAME

ANGLE NONE SAME SAME

TABLE FEED/ROT 3-5 MM VARIES VARIES

PITCH 1 OR 1.6 VARIES VARIES

ROT TIME 1- 2SEC 0.75 SEC 1 SEC

RECON STANDARD/BONE SAME SAME

WINDOW 450W/30L—1600W/600L SAME SAME

HIPS

1

2

3

4

5

1- Head of Femur

2- Acetabulum

3- Fovea Capitis

4- Pubic Bone

5- Ischium

HIPS

1- Pubic Ramus

2- Femoral Neck

3- Ischial Tuberosity

4- Greater Trochanter

1

2

34

HIPS

1

2

1- Symphysis Pubis

2- Lesser Trochanter

HIPS

11- Pubic Bone

HIP CORONAL MPR

1

2

1- SYMPHYSIS PUBIS

2- PUBIC BONE

HIP CORONAL MPR

1

2

3

4

1- Greater Trochanter

2- Acetabulum

3- Femoral Neck

4- Lesser Trochanter

BONY PELVIS

1- Sacrum

2- Ilium

3- S.I. Joint1

2

3