MR Imaging and Angiography of Primary CNS Vasculitis of Childhood

T2-weighted (A), FLAIR (B), and isotropic DWI (C) of a unilateral lesion in a patient with an acute or chronic presentation of worsening right-sided weakness. There are 2 T2-weighted hyperintense lesions involving the genu and posterior limb of the internal capsule (white arrow) and posterolateral putamen (black arrow). Both T2-weighted (A) and FLAIR (B) images reveal lesions of differing age with an anteromedial well-defined encephalomalacic cavity and a posterolateral lesion. The isotropic image (C) confirms a new focal area of infarction within the lateral lenticulostriate artery territory (black arrow) as an area of reduced diffusion.

Fat-saturated T2-weighted MR imaging of bilateral lesions. There is T2-weighted signal intensity abnormality involving bilateral basal ganglia nuclei, thalami, subcortical, and deep white matter, greater on the right. The distribution of abnormality is consistent with both anterior and posterior circulation involvement.

T2-weighted MR imaging. There is expansion and irregular hyperintensity within the right middle cerebellar peduncle extending into the right cerebellar deep white matter and dentate nuclei. Mild fourth ventricular effacement is evident (black arrow). The appearances are consistent with anterior inferior cerebellar artery (AICA) and perforator infarcts.

A, FLAIR demonstrating acute infarct within a superficial distribution. There is cortical swelling and hyperintensity and adjacent patchy subcortical involvement within the right MCA territory. Additional punctate signal intensity abnormalities are present within the right external capsule and parietal deep white matter (black arrows). B, T2-weighted axial MR imaging demonstrating bilateral peripheral infarcts with hyperintensity within deep and subcortical white matter best appreciated within the right frontal lobe. Bilateral cortical involvement and left deep white matter involvement are appreciated more easily on FLAIR (not shown).

Time-of-flight MRA maximum intensity projection (MIP) viewed from posteriorly. The posterior circulation has been removed. There is smooth, regular, concentric, distal left internal carotid and proximal prebifurcation M1 segment flow attenuation (white arrowhead) resulting in reduction in flow signal intensity from remaining MCA branches (white arrow). The A1 segment of the ACA is unaffected. The pattern of proximal involvement was seen in >80% and the “benign” morphology was seen in half of patients studied.

Time-of flight MIP oblique view demonstrating distal involvement of the postbifurcation M1 and proximal M2 segments. There is eccentric, irregular narrowing with alternating stenosis and dilation consistent with beading (white arrowheads). “Aggressive” features are said to be the hallmark of vasculitis but were seen in only 11% of our patients. Multiple additional stenoses are present within the left M2 and P2.