eRadiograph Volume 7: Imaging of Oral Cavity | Page 225

the salivary glands to atrophy as the serous acini of salivary glands are very sensitive to
radiation injury. Sjogren’s syndrome is a systemic autoimmune disorder of the exocrine
glands. This may occur as a solitary finding termed as primary Sjogrens syndrome or
part of an extensive connective tissue disorder. In Sjogrens syndrome there is
destruction of exocrine glands which causes decreased secretions and dryness. The
lacrimal glands and salivary glands are involved, resulting in Keratoconjunctivitis sicca
and Xerostomia. There may be other manifestations such as involvement of articular
cartilage, neurologic, pulmonary or hepatic manifestations. The primary site of disease
involvement is the peripheral intraglandular salivary ducts and acini. During these early
stages cross sectional imaging is negative only a sialogram will demonstrate a normal
central ductal system with peripheral pooling of contrast due to destruction of the
peripheral intraglandular ducts and acini. With disease progression there is dilatation
of the central ducts. At later stages on cross sectional imaging – there is enlargement of
the gland with diffuse increase signal intensity, subsequently there is a honeycomb
appearance to the gland with multiple dilated ducts with a globular appearance. Finally
the gland shrinks in size with deposition of fat and formation of fibrous tissue.
A localized parenchymal mass may also develop known as a benign lymphoepithelial
lesion. This lesion needs to be differentiated from a non Hodgkins lymphoma by a
FNAC as non-hodgkins lymphoma occurs 44 times more in Sjogrens syndrome than
the general population.

Sialolithiasis
This is more common in the submandibular duct than the parotid duct due to the fact
the submandibular duct has an upward curved pathway and there is increase viscosity
in the submandibular saliva. CT is very sensitive in demonstrating stones. Secondary
effects of obstruction such as ductal dilatation, acute/chronic siladenitis may be seen.
Neoplasms
1% of all head and neck malignant tumors arise in the salivary glands. The smaller the
salivary gland, the more likely hood of malignancy. 70 – 80% of tumors in the parotid

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Parotid Space

MR Sialography is a very useful noninvasive alternative to conventional sialography.
The patients saliva is used as a natural agent. Heavily T2 weighted MRI sequences,
which are very sensitive to water are used similar to sequences used for MRCP. MRI
demonstrates the main salivary ducts, normal peripheral salivary ducts are usually not
demonstrated but pathologically dilated are demonstrated. The visualisation of the
ductal system can be better demonstrated by utilising ingestion of water and lime. The
advantages of MRI sialography are it is non invasive, doesn't utilise contrast or
radiation, provides a more physiologic depiction of ductal size. The limitations of MRI
are in individuals with pacemaker, claustrophobia and with dental amalgam as the
artefacts may mar the image quality.