Salivary Gland Imaging

Salivary Gland Imaging

INTRODUCTION

Many different imaging modalities are useful in evaluation of salivary glands. In some

instances, one imaging technique is clearly preferable but in a number of situations the

information can be gathered using one or more approaches. The 2 most important clinical entities

to be imaged are palpable masses and recurrent swelling.



Salivary gland anatomy & physiology




 These are paired glands that secrete a highly modified fluid through a branching duct

system.


 Parotid saliva is released through Stenson’s duct, the orifice of which is visible on the

buccal mucosa adjacent to the maxillary first molars.

,  The orifice of the submandibular duct - the Wharton’s duct is located sublingually on

either side of the lingual frenum. Sublingual saliva enters the floor of the mouth via the

Bartholin’s duct.

There are also thousands of minor salivary glands throughout the mouth, most of which are

named for their anatomic location as labial, buccal palatal etc.


 The glands are composed of acinar & ductal cells. The acinar cells of parotid are serous,

those of sublingual, mucous & submandibular, mixed type.


 Saliva is a highly complex mixture of water & various organic & non - organic

components.


 It has a multitude of functions - lubrication, cleansing, physical protection, buffering

action & antibacterial.


 The secretion of saliva is controlled by sympathetic & parasympathetic neural input.

Applied diagnostic imaging of salivary glands


 Differentiate inflammatory processes from neoplastic disease.


 Distinguish diffuse disease from focal suppurative disease.


 Identify & localize sialoliths.


 Demonstrate ductal morphology.


 Determine anatomic location of tumour.


 Differentiate benign from malignant disease

,  Demonstrate the relationship between a mass & adjacent anatomic structures.


 Aid in the selection of biopsy sites.

Imaging modalities


 Plain films


 Sialography


 Computed tomography ( CT )


 Magnetic Resonance Imaging ( MRI )


 Ultrasound


 Radionuclide salivary study


 Sialoendoscopy

Overall imaging approach


 Plain film radiography is typically the appropriate starting point for imaging of the major

salivary glands from a cost benefit point of view.


 It can demonstrate sialoliths & possible involvement of adjacent osseous structures.


 Sialography remains the only imaging study for examining the fine anatomy of the

salivary ductal system.


 CT or ultrasound is the current standard for investigation of soft-tissue calcifications.

,  CT has about a 10 fold increased sensitivity compared to plain films for detecting soft-

tissue calcifications & one of the primary strengths of ultrasound is its ability to identify

small, solid soft-tissue densities.


 MR imaging is the primay modality of choice when a mass is palpated as it best

delineates the morphology of the mass.


 Functional disorders such as xerostomia are appropriately imaged with sialography or

scintigraphy.


 Nuclear medicine has specific applications. A Tc-99m pertechnate scan shows high

radionuclide uptake in Warthin’s tumour & oncocytoma.

Plain film radiography


 It is the fundamental part of the examination of salivary glands & may provide sufficient

information to preclude the use of more sophisticated & expensive techniques.


 Plain film radiographs are useful when the clinical impression, supported by a compatible

history, suggests the presence of sialoliths.


 Such an examination should include both intraoral & extraoral images to demonstrate the

entire region of the gland.


 It is expedient to use about half the usual exposure to avoid overexposure of the

sialoliths.

Parotid gland

Intraoral view - Periapical film