The role of imaging in the diagnosis of central nervous system vasculitis.

Cerebral vasculitis is diagnosed with difficulty. Its presentation with heterogeneous symptoms and signs often delays diagnosis. In this context, imaging plays an important role in advancing the diagnosis. Digital subtraction cerebral angiography, MRI, and MRA, the most useful examinations for vasculitis, provide supportive, but not pathognomonic, evidence of cerebral vasculitis. On MRI, multiple infarcts in different vascular territories and of different ages are suggestive of vasculitis. On digital subtraction cerebral angiography, areas of stenosis, dilatation, and occlusion are suggestive of vasculitis. Small vessel vasculitis is currently best demonstrated by changes seen in brain parenchyma on MRI, but high field strength (7 T) magnetic resonance angiography offers the possibility of directly evaluating small vessel vasculitis. Ultrasound and high-resolution contrast MRI are excellent modalities for evaluating the superficial extracranial circulation.