Sarcoidosis of the CNS: comparison of unenhanced and enhanced MR images.

Sarcoidosis involving the CNS has a predilection for the leptomeninges, although parenchymal involvement occurs. We retrospectively evaluated the appearance of CNS sarcoidosis on unenhanced and enhanced MR images. MR studies were abnormal in 17 of 20 patients with CNS sarcoidosis. In all 17 patients, meningeal disease was detected on the gadopentetate-dimeglumine-enhanced T1-weighted images; the disease was detected on unenhanced images in three patients. Well-defined leptomeningeal patterns of enhancement were present in 15 patients. Other areas of involvement were the dura; brain parenchyma including hypothalamus, periventricular white matter, and ventricular ependyma; optic chiasm; and pituitary gland. Gadopentetate dimeglumine optimally evaluates meningeal disease and highlights the importance of the leptomeninges and Virchow-Robin spaces in the pathogenesis of CNS sarcoidosis. Enhanced MR is the preferred imaging technique for the evaluation of CNS sarcoidosis.