Primary angiitis of the central nervous system: unusual MR appearance.

The MR findings of a biopsy-proved case of primary angiitis of the central nervous system are described and compared with previously reported cases. Multiple punctate and linear areas of gadopentetate dimeglumine enhancement were present in the brain stem and white matter and appear to correspond to the inflammatory reaction of the small perforating vessels and perivascular tissues seen in the pathologic specimen.