MRI technique zeroes in on Sjögren’s syndrome

Diffusion-weighted MR imaging can conclusively describe abnormalities of the lacrimal glands in patients with Sjögren's syndrome, according to a study from Japan in the April issue of the American Journal of Roentgenology. Although the disease is uncommon and often benign, it can lead to pulmonary and kidney infections, and even lymphoma.

Sjögren's syndrome, which affects the mucous membranes and several glands, occurs mostly in middle-aged women. Its most common symptoms are dryness of the eyes and mouth, which may occur alone or be associated with connective tissue diseases such as rheumatoid arthritis, polymyositis, and systemic lupus erythematosus. The syndrome affects 3% of the population.

Minimally invasive tests currently available to diagnose lacrimal and parotid gland abnormalities are inconclusive. Tests with a higher diagnostic value are more invasive and risky, but specialists value early assessment. Though usually benign, the condition can worsen into complications.

Dr. Yosuke Kawai and radiology colleagues at the University School of Dentistry in Nagasaki enrolled 31 healthy volunteers and 11 Sjögren's syndrome patients with impaired lacrimal function. Researchers applied a single-shot spin-echo planar MR technique using a 47-mm microscopy coil on the 42 subjects to assess the anatomy and function of the lacrimal and parotid glands.

They found the apparent diffusion coefficient of the lacrimal glands in Sjögren's syndrome patients to be significantly lower than that in healthy patients.

Diffusion-weighted imaging of the lacrimal and parotid glands comprised axial and coronal spin-echo T1- and T2-weighted sequences and fat-suppressed turbo spin-echo T2-weighted images at 1.5T. The imaging protocol included a field-of-view of 100 mm, a 160 x 144 matrix, 2-mm slice thickness, and a 0.2-mm slice gap.

Physicians rely too heavily on biopsy, lacrimal flow rate, and rose bengal tests to diagnose autoimmune diseases like Sjögren's syndrome, according to the study. The development of DWI allows the assessment of intraglandular changes and boosts the diagnosis and treatment of patients.

Though the technique is prone to motion artifacts, the use of homogeneity correction technology could improve image quality, the researchers said.

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