Glandular abnormalities:
1) Contrast sialography:(Fig.1)
Sialography is a first radiographic method that can detect anatomic and architectural changes in the salivary gland duct system.
However its drawbacks are due to its invasiveness and the use of contrast media.
The sialographic changes are classified as punctate,
globular,
cavitary,
and destructive dilatation (sialectasia) of the acinar system.
It is the reference standard for staging and appears as alternating areas of ductal stenosis and dilatation (string of beads pattern).
2) Scintigraphy:(Fig.2)
It is a functional method that allows for the evaluation of the salivary gland parenchyma and function in patients with dry mouth.
We inject intravenous 99mTc-sodium pertechnectate,
sequential head images are acquired,
and glandular regions of interest are manually drawn,
followed by a computerized generation of time–activity curves for each major salivary gland.
Time activity curves have two phases: the uptake phase,
corresponding to tracer accumulation in the glandular parenchyma,
and the excretion phase,
initiated by the administration of a salivation stimulator agent,
for example,
citric acid.
The excretion phase corresponds to tracer elimination through the oral cavity and provides information on the functional integrity of the ductal system
The earliest and most common scintigraphic abnormality observed in SS is impairment of excretion,
followed by a decrease in tracer accumulation,
reflecting damage in the glandular parenchyma
Salivary gland scintigraphy is sensitive enough to detect mild abnormalities,
such as 25% destruction of glandular parenchyma,
and its results correlate with clinic-pathological features of SS.
3) Ultrasonography:(Fig.3)
Ultrasonography is an inexpensive and noninvasive technique that is used to detect anatomic changes in the major salivary glands with various
Studies showing its sensitivity to range from 70–95%.
Features of SS include parenchymal inhomogeneity,
hypoechoic foci with hyperechoic bands,
cysts,
calcifications,
and irregular contour of the gland.
Early stages of SS may show normal or increased glandular volume while advanced SS characteristically shows irregular gland contour and parenchymal atrophy
4) Computed Tomography (CT):(Fig.4)
In early stages of SS.
CT shows increasing areas of fat density in the salivary glands caused by glandular destruction that progress to complete fatty replacement with parenchymal atrophy as well as multiple punctate calcifications or microliths in advanced SS.
5) Magnetic Resonance Imaging (MRI):(Fig.5)
High resolution MRI,
using small surface coil.
We obtain conventional T1 and T2 weighted images,
MR Sialography and diffusion-weighted MRI
Staging,
grading & classification:
Stage I: punctate contrast/high signal =/< 1 mm
Stage II: globular contrast/high signal 1-2 mm
Stage III: cavitary contrast/high signal > 2 mm
Stage IV: parotid gland parenchymal destruction
- T1WI: early stages show collections of low signal denoting saliva within dilated ducts. Late stages with increased fat deposition show hypo- and hyperintense areas simultaneously on T1WI (so-called salt-and-pepper appearance).
- T2WI: multiple high signal foci
- T1WI with contrast: heterogeneous mild nodular enhancement of the parenchyma.
- Diffusion-weighted MR imaging has revealed that the apparent diffusion coefficients (ADCs) of the parotid glands in SS patients correlate with the severity of gland damage.
- MR Sialography using a heavily T2-weighted sequence is a promising alternative technique to contrast sialography with a sensitivity of 95%
6) Plain radiographs:(Fig.6)
Punctate calcifications in the parotid glands can be noted.
In addition to extensive dental caries in the late stages of Xerostomia.
Extra-glandular abnormalities:
In addition to the salivary and lacrimal glands,
a variety of systemic organs can be affected in SS.
The commonly affected parts are central/peripheral nervous system,
thyroid gland,
lungs,
gastrointestinal tract,
liver,
kidneys,
vagina,
joints,
muscles,
and skin.
Lymphoproliferative disorders
There’s an increased risk of malignancy in primary SS,
with the relative risk of NHL = 13.8.
The presence of a dominant parotid solid mass +/- cervical lymphadenopathies is worrisome for malignant lymphoma,
the predominant histopathological subtype is MALT lymphomas.
The majority of lymphomas associated with SS initially involve the neck organs including:
• Salivary glands
• Ocular adnexa
• Thyroid gland
• Cervical lymph nodes