Dr.Huda Moutaz Ismail

Department of oral & maxillofacial surgery

University of Baghdad /college of dentistry

Diagnostic imaging in oral & maxillofacial surgery

Diagnostic imaging classified in to :

A-Non invasive imaging which include

1- plain radiographic (conventional)

2-Computed tomography (CT)

3-Magnetic resonance imaging (MRI)

4-Contrast enhanced imaging (sialography ,arthrography )

5-Ultrasonography

6- Nuclear Imaging (SPECT, PET …)

B-Invasive imaging:

This is performed for diagnostic as well as

therapeutic purpose

This include :

-Angiography

-Angioplasty

-Embolization

-Calculus destruction ,others…

Before embolization (left); immediately after embolization(middle); and, 12 months following embolization (right). Angiography

Non invasive imaging technique :1-plain conventional radiograph

A-intra-oral radiograph :

A-Periapical

B-Bite-wing

C-Occlusal include : >> Maxilla (occlusal view )

-Mandible (occlusal view )

- Upper standard occlusal -Upper oblique occlusal-Vertex occlusal

Lower 90° occlusal Lower 45° occlusal Lower oblique occlusal

B-Extra oral radiography :

• Standard occipitomental (0° OM)

• 30° occipitomental (30° OM)• Postero-anterior of the skull (PA skull)sometimes referred to as occipitofrontal (OF)

• Postero-anterior of the jaws (PA jaws)• Reverse Towne's• Submento-vertex (SMV)• Transcranial• Transpharyngeal.

-Lateral radiographs of the head and jaws are

divided into:

• True laterals

• Oblique laterals

• Bimolars (two oblique laterals on one film).

Lateral jaw projection (lateral oblique projection).Key words :

•To Examine the posterior region of the mandible, impacted teeth ,lesions, fracture etc..•Valuable in children, or Senile patients who can’t withstand intraoral films or unconscious patient.

-Cassette is positioned flat against the cheek and centered over the mandibular first molar area.-Head position is tilted about 10 to 20 degree toward the side to be examined and the chin is protruded.

Oblique lateral radiographic of # of the left body and angle.

Lateral skull (cephalometric )projection:

This projection shows the skull vault and facial skeleton from the lateral aspect.

Purpose : Conditions affecting the sella turcica, • Fractures of the cranium and the

cranial base • Investigation of the frontal, sphenoidal and maxillary sinuses

Chromophobe adenoma; pituitary adenoma

Sella turcica (lateral projection): destruction by tumour

Submandibular sialolith

Eagles' syndrome

Bimolar technique

Bimolar is the term used for the radiographic projection

showing oblique lateral views of the right and left sides of the

jaws on the different halves of the same radiograph.

Standard occipitomental (0° OM)Water’s view projection (sinus projection)

Key points :-Purpose: To Evaluate the maxillary , frontal and ethmoid sinuses ( paranasal sinus).-Detect middle third fractures (Le fort I,II,III) , Coronoid process fracturesNote : The patient facing the film with the head tipped back so the radiographic baselineis at 45° to the film, The X-ray central ray horizontal (0°) centred through the occiput

Le fort II fracture

Occipito Mental 30° (OM30) View Standard occipitomental (0° OM)

the head tipped back, radiographicbaseline at 45° to the film, the central ray at 30° to the horizontal.

the head tipped back, radiographicbaseline at 45° to the film, the central ray at 0 to the horizontal.

Key points :

-This projection shows the skull vault, primarily the frontal bones and the jaws.

-The beam passes through the skull in a posterior to anterior direction.

Purpose: Asymmetry , Developmental abnormalities ,fracture of the skull vault.

• Conditions affecting the cranium, particularly:

— Paget's disease

— Multiple myeloma

— Hyperparathyroidism

Note : The X-ray tubehead is positioned with the central ray horizontal (0°) centred through the occiput

Posteroanterior skull (PA) projection:

Asymmetry

Posteroanterior radiographic view of

a fracture of the left body and angle.

Postero-anterior of the jaws(PA jaws/PA mandible)

Purpose : • Fractures of the mandible ,lesions such as cyst or tumor in post 1/3 of body & in ramus of mandible ,condylar hypoplasia or hyperplasia

The PA view is used to evaluate the entire mandible. However, the symphysis is often obscured by the cervical spine, and the condylescan be superimposed over the mastoid process and occipital bone. A Waters view or a basal view should be obtained to better evaluate

the symphysis to negate the overlap of the cervical spin.

Note :The X-ray tubehead is again horizontal (0°), but now the central ray is centred through the cervical spine at the level of the rami of the mandible

Reverse –towne projectionKey points:

This projection shows the condylar heads and necks.

Purpose to examine fractures of the condylar neck of the mandible ,Condylar

hypoplasia or hyperplasia..

Submentovertex projectionKey words : This projection shows the base of the skull, sphenoidal sinuses and facial skeleton

from below.

Purpose :• Destructive lesions affecting the palate, pterygoid region or base of skull• Investigation of the sphenoidal sinus• Assessment of the thickness (medio-lateral) of the posterior part of the mandible beforeosteotomy• Fracture of the zygomatic arches

Lateral Transcranial View of TMJ

Main indicationsThe main clinical indications include:• TMJ pain dysfunction syndrome and internalderangements of the joint producing pain,clicking and limitation in opening• To investigate the size and position of the disc— this can only be inferred indirectly from therelative positions of the bony elements of thejoints

TranspharyngealMain indicationsThe main clinical indications include: TMJ pain dysfunction syndromeTo investigate the presence of joint disease, particularly osteoarthritis and rheumatoidArthritis ,to investigate pathological conditions affecting the condylar head, including cysts or tumours ,fractures of the neck and head of the condyle.

Disadvantage of conventional plain radiograph :-Ionizing radiation (X ray) -Two dimensional image of 3D object-Superimposition - It can't detect early pathology unless at least 30% of mineral is changed

Test yourself

-Patient with fracture mandible

Imaging modalities ?

-fracture of zygomatic arch

Imaging modalities ?

2- computed tomography (CT scan) or computed axial tomography (CAT scan)

Key points:

-Introduced in 1974 by Sir Jeffrey Hounsfield

-A CT image is a computer-generated picture based on multiple x-ray exposures taken around the

periphery of the subject.

-It is made in variety of planes (axial ,coronal ,sagittal ) ,Most CT is done in the axial Plane.

-Slice thickness is usually 5 mm through the head and neck, unless three dimensional

reconstruction is anticipated. In such cases, the slice thickness

is 1.0 to 1.5 mm in order to provide adequate data.- It take 20-30 min

-The images are usually viewed in two modes: bone windowing and soft-tissue windowing.

- Bone windowing > contrast is set > so the osseous structures visible in max details

-Soft-tissue windowing, the bone looks uniformly white, but various types of soft tissues can be

distinguished

Windowing allows the CT scan reader to focus on certain tissues within a CT scan that fall

within set parameters.

What Is Bright on CT?

• Blood

• Contrast

• Bone

• Calcium

• Metal

• Why?

What Is Dark

on CT?•Air

•CSF/H20

•Fat

•Why?

What is gray =?The denser the object, the whiter it is on CT

This ability to block x-rays as they pass through a substance is known as attenuation.

Substance HU

Air −1000

Lung −500

Fat −84

Water 0

CSF 15

Blood +30 to +45

Muscle +40

Soft Tissue, Kontrastmittel +100 to +300

Bone+700(cancellous bone)to +3000 (dense bone)

The HU of common substances

The Hounsfield scale applies to medical grade CT scans

but not to cone beam computed tomography (CBCT) scans

(the x ray attenuation value of ct scan are scored )

Purpose : CT is typically used to evaluate

(1) The extent of lesions suspected or detected with other radiographic techniques,

(2) In maxillofacial Trauma

(3) Evaluation of the paranasal sinuses & salivary glands

(4) In evaluation of dental implant site

5) Cervical L.N & neck masses

Note : CT is rarely indicated for evaluation of the TMJ since the osseous structures can

be visualized adequately with less expensive techniques such as conventional

tomography or panoramic radiography, and disk displacement and other joint soft-tissue

information can be better obtained with magnetic resonance imaging.

Fracture

osteosarcoma

CT scan

Fan beam Helical CT (HCT)Key points -bone , soft tissue & air window

Cone beam(CBCT)

Types of CT ScannersComputed tomography can be divided into 2 categories based on acquisition x-ray beam geometry; namely: fan beam and cone beam

Multiplanar reconstruction

Multiplanar reconstruction (MPR) is the

simplest method of reconstruction. A volume is

built by stacking the axial slices. The software

then cuts slices through the volume in a different

plane (usually orthogonal). As an option, a

special projection method, such as maximum-

intensity projection (MIP) or minimum-intensity

projection (mIP), can be used to build the

reconstructed slices

Contrast Ct scan:Contrast media/dye is a special fluid introduced into the body. It is used to“highlight” the area of the body being scanned.

Intravenous injection through a vein to highlight blood vessels & other structures It is an iodine-based dye.

Orally taken for an abdomen CT scan (drink 2-3 glasses of oral contrast 20-30 min before the scan.

Case : Aneurysmal bone cyst A. Cropped panoramic radiograph shows that the lesion grows largely and the internal septa showmultilocular soap bubble appearance five months later. B. Coronal contrast enhanced CT scan shows an expansile,multilocularosteolytic lesion with multiple internal septation and multiple fluid levels within cystic spaces at the left mandible.

False positives/negativesCT findings should not be interpreted in isolation, and scans should always be read in conjunction with clinical and endoscopic findings because of high rates of false-positive results. Up to 40% of asymptomatic adults have abnormalities on sinus CT scans, as do more than 80% of those with minor upper respiratory tract infections.

CT angiography

A CT Angiography (CTA) is a minimally invasive technique that helps physicians diagnose and treat medical conditions. Angiography uses one of three imaging technologies:-X-rays with catheters-Computed tomography (CT)-Magnetic Resonance Imaging (MRI)A CT angiogram is a less invasive procedure than a standard

angiogram. A traditional angiogram procedure involves inserting a catheter through artery; while with a CT angiogram exam no catheters or tubing is involved.

- During a CT angiogram. A special dye (contrast material) painlessly injected into the veins using an IV in your arm or hand.

Computed Tomographic Arteriography (CTA) with 3D reconstruction gives us the advantages of contrast arteriography

Fig. . CT angiography (64 slices, GE Healthcare Technologies) of a maxillofacial AVM for treatment planning. In- and outflow can be clearly differentiated, the maxilla is not destroyed.

Magnetic resonance imaging (MRI)

It use electrical and magnetic fields and

radiofrequency (RF) pulses, rather than ionizing radiation

to produce an image.

Key points :

-The patient is placed within a large circular magnet

that causes the hydrogen protons of the body to be aligned

with the magnetic field.

-It acquire image in 3 planes

Two distinct views are typically generated:

T1 and T2. Adipose tissue has the highest signal in the T1-weighted

image, and this view is often used for identifying anatomic structures

water appearing darker and fat brighter.

By comparison, the T2 image highlights tissues with high water

content and is especially useful in depicting inflammatory processes

and neoplasms. fat is differentiated from water, but in this case fat

shows darker, and water lighter, eg. in the case of cerebral and spinal

study, the CSF (cerebrospinal fluid) will be lighter in T2-weighted

images

-The typical MRI examination of the TMJ consists of bothclosed- and open-mouth views in an oblique sagittal plane.

-MRI key points :--In dentistry, the primary uses of MRI have been the evaluation of various pathologic lesions (such as tumors) and the assessment of the TMJ, salivary glands .-To define the extension of soft T tumor -To distinguish fluid from tumor in Paranasal sinus -Relationship of major B.V to S.T tumor-visualize the anatomy of cranial nerves

Figure. (A) CT of a patient with maxillary sinus cancer demonstrates bony destruction, (arrow) a hallmark of malignancy. (B) MRI in the same patient more accurately distinguishes between the intermediately enhancing tumor (long arrow) lining the maxillary sinus and the non-enhancing secretions (short arrow) filling the maxillary sinus.

Figure 1. MRI and autopsy midcondyle anatomy of normal temporomandibular joint: upper left oblique sagittal MRI, upper right oblique coronal MRI, lower left oblique sagittal section, lower right oblique coronal section (Maxillofacial Imaging.2006[28]

The major disadvantage of MRI -Very loud continuous hammering noise when operating

-Some people are too big to fit inside the magnet

- Long periods of time ... up to 90 minutes

-Cost

-Contraindicated for certain patients,

Eg/patient with cardiac pacemakers, due to interference by

the electrical and magnetic fields. Patients with ferromagnetic metallic objects in strategic

places (such as aneurysm clips in the brain and metallic fragments in the eye) also should

not be placed in the magnet.

-Some patients feel claustrophobic inside the magnet and

may need to be sedated for the procedure.

in this figure Coronal pre- (A) and postgadolinium (B) T1-weighted MR images of the ABC. Note the contrast enhancement of intracystic septae.

Contrast MRIMRI contrast agents may be administered by IV injection

or orally, depending on the subject of interest-The most commonly used compounds

for contrast enhancement are gadolinium-based.

-Used for enhancement of vessels in MR angiography or for brain tumor ,For large vessels

such as the aorta and its branches, the gadolinium(III) dose can be as low as 0.1 mmol per

kg body mass. Higher concentrations are often used for finer vasculature

Gadolinium ion (highly magnetizable) chelated to a molecule that won’t pass an intact blood-brain barrier

Makes T1-weighted images brighter where it accumulates and makes T2- and T2*-weighted images darker

Figure 5. Preoperative Gadolinium-enhanced T1-weighted MRI. Locally advanced tumor (arrow) in the base of the tongue invaded the epiglottis (arrow head).

magnetic resonance (MR) angiography is an alternative to conventional angiography and CT angiography, eliminating the need for iodinated contrast media and ionizing radiation

-Non contrast enhanced MR angiography

A variety of techniques can be used to generate the pictures, such as administration of a paramagnetic contrast agent (gadolinium) or using a technique known as "flow-related enhancement", where most of the signal on an image is due to blood that recently moved into that plane

Nuclear Medicine

Key points:

-Radionuclide imaging is the technique of producing diagnostic images by analyzing the

radiation emitted from a patient who has previously been given radioactive medications

-Nuclear medicine differs from most other imaging modalities in that the tests primarily

show the physiological function

-It is based on the cellular function and physiology, rather than relying on physical

changes in the tissue anatomy

This is done by injecting certain radioactive compounds into the patient that have an

affinity for particular tissues — so-called target tissues.

Several radioisotopes are used in conventional nuclear medicine, depending on the tissue

under investigation

Eg/ Technetium (99mTc) — salivary glands, thyroid, bone, blood, liver, lung and heart

Main indications for conventional isotope imaging in the head and neck• Tumour staging — the assessment of the sites and extent of bone metastases• Investigation of salivary gland function, particularly in Sjogren'ssyndrome • Evaluation of bone grafts• Assessment of continued growth in condylar hyperplasia• Investigation of the thyroid• Brain scans and assessment of a breakdown of the blood-brain barrier.

Single Photon Emission Computed Tomography

(SPECT) /Key points:

• Single photon emission computed tomography (SPECT), where the photons (gamma rays) are emitted from the patient and detected by agamma camera rotating around the patient 360 and the distribution of radioactivity is displayed as a cross-sectional image or SPECT scan enablingthe exact anatomical site of the source of the emissions to be determined.

- Acquiring rotating delayed static images, generally sixty-four projections over 360º

-SPECT offers the possibility to widen the observational time window (owing to the

longer half life of single photon emitters) thus allowing biomedical scientists to observe

biological processes in vivo several hours or days after administration of the labeled

compoundSPECT

Nuclear Medicine

Tc-99m Radioactive decay Gamma ray/photon emission(140KeV)

Gamma cameraImage

Positron Emission Tomography (PET) (PET) is a nuclear medical imaging technique that detect alterations in biochemical processes that suggest disease before changes in anatomy are apparent with other imaging tests, such as CT or MRI.

-Radionuclides used in PET scanning are typically isotopes with short half-lives such as carbon-11 (~20 min), nitrogen-13 (~10 min), oxygen-15 (~2 min), fluorine-18 etc... These radionuclides are incorporated either into compounds normally used by the body such as glucose (or glucose analogues), water, or ammonia, or into molecules that bind to receptors or other sites of drug action. Such labelled compounds are known as radiotracers.

-the most commonly used radiotracer in clinical PET scanning is fluorodeoxyglucose18F) 18F-FDG or FDG,.(it is used in > 95% of PET scan )

To conduct the scan, a short-lived radioactive tracer isotope is injected into the living subject (usually into blood circulation).

The tracer is chemically incorporated into a biologically active molecule. There is a waiting period while the active molecule

becomes concentrated in tissues of interest; then the subject is placed in the imaging scanner. The molecule most commonly

used for this purpose is fluorodeoxyglucose (FDG), a sugar, for which the waiting period is typically an hour. During the scan a

record of tissue concentration is made as the tracer decays.

Positron Emission Tomography - PET

Radionuclide with excess protons

Decay

Positrons

Positron + electron collision

Annihilation reaction generates two 511-keV gamma photons

PET detector ring for localization & imaging

-PET can give false results if a patient's chemical balances are not normal. Specifically, test results of diabetic patients or patients who have eaten within a few hours prior to the examination can be adversely affected because of blood sugar or blood insulin levels.

-limitation is inability to provide information about exact localization of the lesion because lack of anatomic landmarks

-Radioactive substance IV 30 to 90 minutes for the substance to travel and accumulate in the tissue .After that time, scanning begins. This may take 30 to 45 minutes.

-PET detects area of increased metabolic activity as indicated by uptake of radioactive glucose (tumor, infection)

Cancerous tissue, which uses more glucose than normal tissue, will

accumulate more of the substance and appear brighter than normal

tissue on the PET images

PET/CT : is hybrid system -Combined functional imaging of PRT & anatomical imagingof CT scan

-More accurate staging-More Accurate Surgical Planning-More Accurate Guided Biopsy-More Accurate RT Planning-Monitoring response to therapy & post operative recurrence

Fig. 9. (a) CT; (b) FDG; (c) FDG PET/CT. Intense FDG uptake due to a Warthin's tumour within the left parotid gland (arrow).

Fig. 3. Mouth floor carcinoma T4N2M0 invaded the tongue and alveolar region of the mandible. (A) Sagittal PET; (B) sagittal CT, reconstruction of HRCT; (C) sagittalPET/CT fusion; (D) sagittal image of the involved lymph nodes, PET; (E) CT; (F) PET/CT fusion.

Figure 5 Large cell lymphoma in a patient who presented with a shallow ulcer in the hard palate. Axial fused PET/CT image shows a large focus of abnormally increased FDG uptake in the hard palate (arrow), a finding that is suggestive of squamous cell carcinoma. However, histologic analysis of a biopsy specimen demonstrated non-Hodgkin large cell lymphoma.

Carcinoma of the tongue T1N0M0. (A, B) Primary staging,

PET/CT; (C, D)

restaging after partial glossectomy 6 months previously

showing local recurrence in the resection line and in the oral cavity

bottom.

• Figure 2. An 83-year-old woman with a history of squamous cell carcinoma of the left mandible. The patient was staged as N0 on clinical examination. 18F-FDG-PET and CT obtained preoperatively. The primary tumor is hypermetabolic (top arrow). There are multiple hypermetabolic foci in the left cervical region corresponding to levels 1, 2, 3, and 4 lymph nodes (middle and bottom arrows). Composite resection of the left mandible and neck was performed 2 weeks after the imaging study. Pathology on the composite resection specimen revealed 35 of 40 lymph nodes positive for metastatic cancer.Nahmias et al. PET/CT Staging in Oral/Head and Neck Cancer. J Oral Maxillofac Surg 2007.

•

Reccurent mouth floor carcinoma. Highly increased 18F-FDG was found

in tumorous tissue, the mild increase in 18F-FDG accumulation is in the

overused styloglossus muscle. (A) Axial PET/CT fusion; (B) coronal

PET/CT fusion; (C) sagittal PET/CT fusion.

Scintigraphy is a form of diagnostic test used in nuclear medicine, wherein radioisotopes

(here called radiopharmaceuticals) are taken internally, and the emitted radiation is

captured by external detectors (gamma cameras) to form two-dimensional images. In

contrast, SPECT and positron emission tomography (PET) form 3-dimensional images,

and are therefore classified as separate techniques to scintigraphy, although they also use

gamma cameras to detect internal radiation.

Bone scintigraphyevaluate for metastatic bone cancer, primary bone tumor , evaluate the extent of osseous inflammation , osteomyelitis., arthritis ,to evaluate abnormal metabolism or growth in the skeleton (metabloic disorder) …

Bone scans (scientigraphy) -Most common Technetium-99m which has a 6 hour half life with

good detector , with MDP

NORMAL BONE SCAN”

Over 3-4 hrsMDP (HDP) is accumulatedinthe bonesand in thelesions proportional to Blood Flow and to OsteoblasticActivityExcretionof

Normal results

The normal appearance of the scan will vary according to the

patient's age. In general, a uniform concentration of radionuclide

uptake is present in all bones in a normal scan.

Areas that absorb little or no amount of tracer appear as dark or "cold" spots. Areas of fast bone growth or repair absorb more tracer and show up as "hot" spots in the pictures..

Abnormal results

Bone scanning

Hot spotsuptake

Cold spotsuptake

TYPICAL “HOT”SPOTBONE SCANS

METASTATIC PROSTATE CANCER

Metastasis: “cold”Lesion Prostate Cancer

A 73-y-old woman, affected by multiple myeloma, previously treated with bisphosphonates. (A) Orthopantomography showed area of bone cortical irregularity (circled) in right mandible. (B) Three-phase bone scanning revealed increased blood pool (circled). (C) Hybrid SPECT/CT allowed definition of area of osteonecrosis (arrow) with neighboring hyperactive viable bone.

Bone Scintigraphy and SPECT/CT of Bisphosphonate-Induced Osteonecrosis of the Jaw

Ultrasonography

U- Ultrasound > 20 kHz; / for medical usage typically 2-10 MHz

This is a noninvasive and relatively inexpensive

technique for imaging

The probe converts electrical energy in to high frequency sound waves

Which pass in to tissue of different densities

The vibration energy of US is reflected back to the scanning

transducer Where the sound converting in to image

Reflection of US wave by different tissue :

-Fluid pass without reflection

-bone & lung All are reflected and not allowed to pass

-Soft tissue Waves are partly pass

Ultrasonography is most useful in the evaluation of deeply

seated masses and is often helpful in distinguishing

a solid mass from one that is cystic.

Regarding head and neck region it is used to evaluate

-Salivary glands

-Lymph node

Dual-energy x-ray absorptiometry (DEXA) First, obtain plain radiographs if a decrease in bone mineral density is suspected

Osteopenia may be apparent as radiographic lucency but is not always noticeable until

30% of bone mineral is lost

Plain radiography is not as accurate as BMD testing (bone mineral density )Devices that measure BMD include:

-Quantitative computed tomography -Dual-energy x-ray absorptiometry (DEXA) -Quantitative ultrasonography-Radiogrammetry

Dual energy x-ray absorptiometry (DXA) scan of edentulous person. Regions of interest are superimposed over maxilla and mandible and bone mineral density calculated with computer software.

DEXA : Dual-energy x-ray absorptiometry requires less radiation, is less expensive, and has better reproducibility than quantitative computed tomography-The DEXA machine uses a special, low, dose x- ray.-It has become the standard method for determining bone density. -This method can be used in both adults and children-Results are reported as two values, T and Z scoresT-score'. your bone density compares to the normal average for young, healthy adults whose bone density is at its peak. A T-score of 0 means your bones are the same density as an average young.- 0 and -1 indicates the bone density is normal

-Between -1 and -2.5 indicates bone density is below normal, or osteopenia

-Below -2.5 indicates osteoporosis

sialography-Conventional sialography >>>

-Used for evaluating the ductal system of the major salivary glands

-Contrast medium is injected into the major duct of the salivary gland of interest ,

It is also contraindicated during acute infection because of possible exacerbation.

There is a modality CT sialography & MRI sialography.

SialographyEquipments1.Sialographiccannulas – tips ranging from 0.012 – 0.033.2.Lacrimal dilators.3.5ml / 10 ml syringe.4.Contrast media5.Secretogauges – fresh lemon etc-(about 0.7 ml for the parotid gland, 0.5 ml for the submandibular gland).

Lateral-oblique conventional sialographicimage obtained after MR sialography confirms the diagnosis of sialolithiasis and shows the distal displacement of the calculus (long straight arrow) caused by active filling of the ductal system. Bartholin duct (curved arrow) and primary (large arrowhead), secondary (small arrowheads), and tertiary branches (short straight arrow) are slightly dilated. The calculus was removed endoscopically.

Figure 1: Sialogram of the right and left parotid glands with juvenile recurrent parotitis demonstrates sialectasis (arrow) on the panoramic radiograph

Normal Sialographic Appearance of the Parotid Gland

The main duct is of even diameter (1-2 mm wide) filled completely.

The duct structure within the gland branches -regularly and tapers gradually

towards the periphery of the gland, the so-called tree in winter appearance

Sialographic appearances of sialadenitis

Dots or blobs of contrast medium within the gland , an appearance known as

sialectasis caused by the inflammation of the glandular tissue producing

saccular dilatation of the acini.

MRI sialographyKey points :

-Non invasive technique (not requiring cannulation )

-No contrast ( saliva act as a contrast media )

-No radiation

But

the spatial resolution of these techniques remains limited when compared

with X-ray

techniques in the evaluation of the branch ducts and the morphological

changes of early sialectasis.

-MR imaging was performed at least 4 hours after contrast-enhanced digital

sialography to allow normal salivation to wash away air bubbles. ( sometimes

the air bubbles are inadvertently injected with the contrast material)

-Prior to MR imaging, the patients were given lemon juice or sialogogue to

stimulate salivation, because saliva act as contrast media

Parotid duct strictures - MR sialography

Dilated left parotid duct with mutiple

strictures (arrows)

Heavily T2 ( T2W fat-suppression sequence)

-Heavy T2 weighting was achieved On T2-weighted turbo spin-echo MR images, saliva in the salivary ductal

system was hyperintense, and sialoliths were

hypointense.

- Thus, heavily T2-weighted sequences were the first

choice in MR sialography.

-An MR sialogram was acquired in an oblique sagittal

orientation, others .

• Discrepancy in imaging features of the parotid glands between MR sialography and conventional sialography.A–J, MR sialograms (A–E) and conventional sialograms (F–J) of the parotid glands in xerostomia patients with or without Sjögren’s syndrome: grade 0 (A and F), grade 1 (B and G), grade 2 (C and H), grade 3 (D and I), and grade 4 (E and J). Note apparent differences in sialographic features at grade 4 (E versus J).

Thank you