Cerebral vasculitis: MR imaging and angiographic correlation.

Cerebral vasculitis is an unusual disorder with numerous causes. One such entity, noninfectious granulomatous angiitis of the nervous system (GANS), is an extremely rare disease with a predilection for leptomeningeal and parenchymal arteries and veins. Isolated involvement of the central nervous system is characteristic of GANS, which has also been referred to as primary angiitis of the central nervous system (PACNS). The results of magnetic resonance (MR) imaging and angiography in seven patients with presumed PACNS were retrospectively analyzed and correlated. MR images were positive in every case. Characteristically, lesions were multiple, bilateral, and supratentorial. Both gray- and white-matter infarcts were identified in four of seven patients; infarcts were most common in the deep white matter. PACNS can also appear as primary parenchymal hemorrhage or simulate low-grade glioma. All lesions identified on MR images were associated with positive angiographic findings of cerebral vasculitis in the corresponding vascular distribution. However, for 12 of 33 vascular distributions with angiographic evidence of cerebral vasculitis, no lesions were identified on MR images. These correlative observations suggest that some patients with proved PACNS may have normal MR imaging results.