Applied diagnostic imaging of salivary glands

TASHI FUTI SHERPA

ROLL NO: 37

BDS 4TH YEAR

APPLIED DIAGNOSTIC IMAGING OF SALIVARY GLANDS.

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CONTENTS : Introduction

Strategies for diagnostic imaging

• Projection radiograph

• Conventional sialography

• Computed tomography

• Cone beam computed tomography

• Magnetic resonance imaging

• Scintigraphy

• Ultrasonography

• Sialoendoscopy

Summary

References

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INTRODUCTION Diagnostic imaging of salivary gland diseases

may be undertaken

To diffrentiate inflammatory process from neoplastic disease

To distinguish diffuse disease from focal suppurative disease

To identify and localize sialoliths

To demonstrate ductal morphology

To determine the anatomic location of tumor

To diffrentiate benign from malignant disease

To aid in selection of biopsy sites

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STRATEGIES FOR DIAGNOSTIC IMAGING.Imaging modalities available to assess salivary

glands include:

• Projection radiograph

• Conventional sialography

• Computed tomography

• Cone beam computed tomography

• Magnetic resonance imaging

• Scintigraphy

• Ultrasonography

• Sialoendoscopy

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PROJECTION RADIOGRAPH- Fundamental part of the examination of salivary

glands.

- Two dimensional images acquired which can demonstrate moderaely calcified sialoliths and possible involvement of adjacent osseous structures.

-Intraoral radiography

-Extraoral radiography

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INTRAORAL RADIOGRAPHY:

• Intra oral occlusal view is helpful.

• Sialoliths in anterior two thirds of the submandibular ducts are typically imaged by cross-sectional mandibular occlusal projection.

• The posterior portion of duct may be demonstrated with over the shoulder occlusal projection.

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• Parotid sialoliths difficult to demonstrate tortuous course of Stensen’s duct around the anterior border of masseter.

• As a rule, only sialoliths anterior to the masseter muscle can be imaged on an intraoral image.

• Intraoral image receptor placed inside the cheek as high as possible in the buccal sulcus. Central ray is directed perpendicular to the centre of receptor.

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Fig: Mandibular occlusal view

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Fig: over the shoulder occlusal projection reveals a sialolith.

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EXTRAORAL RADIOGRAPHY:

Parotid gland.• PA view• Panoramic projection

Submandibuar gland.

• Lateral view• Panoramic projection

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Fig: pantamograph , calculus in distal segment of left wharton”s duct.

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Fig: parotid sialolith superimposed over condylar neck.

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CONVENTIONAL SIALOGRAPHY• First performed in 1902

• It is a radiographic technique where a radiopaque contrast agent is infused into the ductal system of a salivary gland before imaging with plain films/digital image receptors, panoramic radiographhy,

CBCT imaging or MDCT imaging.

ADVANTAGES:

- multiplanar and 3D visualization of ductal structures

- Ability to remove overlapping anatomic structures

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• The ductal systems of parotid & submandibular glands are most readily studied.

• A survey or “scout” image aid in verifying the optimal exposure factors and patient positioning parameters as well as detection of radiopaque sialoliths or extraglandular pathosis.

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Indications :• Detection of sialoliths or foreign bodies.

• Evaluation of fistulae,strictures,diverticula,communicating cysts & ductal trauma.

• Evaluating the extent of irreversible ductal damage.

• Diffrentiating between diseases.

• Evaluation of masses within the salivary glands.

Contraindications:• Allergic to contrast agent.

• Malignant lesions

• Acute infections.

• Pregnancy

• Immediately anticipated thyroid function tests.

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TECHNIQUE:

Lacrimal dilators:dilate the sphincters at ductal orifice

Passage of cannula connected by extension tubing to a syringe.

Slowly infuse the contrast solution.

Filling phase monitored by fluoroscopy or projection images.

-The image of ductal system appears as “tree limbs”.-With acinar filling,the “tree” comes into “bloom”.

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• The gland is allowed to empty for 5 mins without stimulation.

• Sialogogues such as lemon juice or 2% citric acid augment evacuation.

• The opacified gland can be imaged with:

Projection radiographs

CBCT

MDCT

MRI

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COMPUTED TOMOGRAPY:• Provides precise anatomical detail.

• Detects calcifications with high sensitivity .

• Indicated for evaluation of masses or generalized enlargement of glands, acute inflammatory processes or abscesses.

• Poor visualization of salivary ducts inferior to sialography.

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Fig: axial view demonstrates bilateral enlargement of parotid glands.

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CONE-BEAM COMPUTED TOMOGRAPHY • Minimally calcified sialolithiasis is well

depicted

• Provides three-dimensional visualization of ductal structure

Fig:submandibular sialolith

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MAGNETIC RESONANCE IMAGING:• Noninvasive & nonionizing radiation

• Best contrast resolution of soft tissues

Indications:• Evaluating parenchymal masses/ cystic lesions

• Neoplasia

• Sublingual masses

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Advantages :

• Noninvasive & use nonionizing radiation

• Excellent soft tissue contrast resolution.

Disadvantages:

• Contraindicated with pacemaker or metal implant.

• Long imaging time

• High cost

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MR SIALOGRAPHY

• Allows for precise morphological evaluation of salivary ducts & enables the visualization of tertiary branches.

• Performed before/after stimulation with lemon juice.

• It can reveal:

- intraglandular duct dilatation

- reveals stenoses

- Very tiny stones

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MR Sialography of left submandibular gland.

Dilated proximal segment of wharton”s

duct

Dilated intraglandular salivary duct

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SCINTIGRAPHY:

• Uses radioactive atoms or molecules that emit gamma rays

• Distribute in the body according to chemical properties

• Gamma camera detects gamma rays and forms planar images.

Indicated in patients when sialography is contraindicated or cannot be performed.

Sod. Pertechnetate (technetium99) is the commonly used element.

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• i.v injection of Tc-99m pertechnate is performed with gamma camera images obtained in every2 mins.

• Radionuclide appears in the ducts within minutes & reaches maximal concentration within 30-45 mins.

• A sialogogue is then administered to evaluate secretory capacity.

Abnormalities may be demonstrated by an increased, decreased or absent radionuclide uptake.

Increased uptake is seen in – Warthin”s tumor

- Oncocytomas

- Sialadenitis

- Granulomatous disease

- Resulting in formation of “hot spot”

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Fig: salivary gland scintigraphy showing parotid and submandibuar glands.

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ULTRASONOGRAPHY:

• Technique based on sound waves that acquires images without the use of ionizing radition.

• The primary application are the diffrentiation of solid masses from cystic ones & guided FNAC.

• More recent studies suggest thet this technique may also be helpful in detecting sialoliths & dignosing autoimmune lesions( Sjogren”s syndrome )

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Fig: ultrasonogram of submandibular gland , salivary stone in Wharton”s duct.

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SIALOENDOSCOPY• Introduced in 1990’s

• Allows direct visualisation of salivary duct lumen i.e

- Calculi

- Mucosal plugs

- Foreign bodies

- Polyp

• Enabled the surgeons to examine the duct from inside

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Fig: A.sialoendoscopic view of intraglandular branches of stensen’s duct B.sialoendoscopic view of calculus inside the wharton’s duct

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SUMMARY

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REFERENCES

• Oral radiology – principles & interpretation

- Stuart C. white

- Micheal J. pharoah

• Salivary gland calculi – contemporary methods of imaging (pol J radiol,2010 july-sep;75(3) PMC3389885 )

- Iwona rzymska ,Zygmunt stopa, Bartomiej grala,

Marek golebioski, Hubert wanyura, Monika sawika

• Burket”s oral medicine , 11th edition

- Greenberg

- Glick

- Ship

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Thank you !

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QUESTIONS:

• 1. injection technique: -hydrostatic injection

• Distention injection

• Hand injection

• Contraindications of sialography:

• Allergic to contrast agent

• Malignant lesions of salivary gland

• Pregnancy

• Acute salivary gland infections

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• Evacuation phase of sialography

• Non stimulated

• Stimulated

• Contrast agents:

• Lipiodol

• Conray 80

• Myodil

• Amipaque

• sinographin