Figure 5.

Axial (a) and coronal (b) TSE T2w MRI of an 8 year-old girl with NF1, showing reduced visualization of left cavernous-supraclinoid internal carotid and proximal left middle cerebral arteries’ flow void (black arrows). Time-of-flight 3D MR angiography maximum intensity projection (c) confirmed the severe stenosis of left internal carotid artery and proximal segment of left middle cerebral artery, whereas distal segments are partly supplied by collaterals; dotted line region magnification (d) showed multiple small collateral vessels in proximal left middle cerebral artery region (white arrow). Axial time-of-flight 3D MR angiography (e) confirmed a reduction in distal middle cerebral artery branches flow (white arrowhead), with a diffuse net of prominent leptomeningeal collaterals with high signal on FLAIR (f) due to slow flow (black arrowhead).