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FIG 3. Patient 3.
A and B, Axial T2-weighted (3400/119/1) (A) and contrast-enhanced T1-weighted (600/14/2) (B) MR images show the nonenhancing left frontal lesion.
C, Corresponding contrast-enhanced CT scan shows a nonenhancing hypodense white matter lesion.
D and E, Arterial (D) and venous (E) phase DSA images (lateral projection) from the accompanying left ICA stereo angiogram depict a region of arteriovenous shunting corresponding to the location of the MR abnormality. An area of abnormal parenchymal blush (curved open arrow) is associated with arteriovenous shunting, resulting in the early opacification of an anterior caudate vein (arrowhead), which empties via the thalamostriate trunk into the left internal cerebral vein (straight arrow). Contrast within the vein of Galen is identified during the arterial phase (curved solid arrow, D).
F, Histopathologic specimen from the region of abnormal parenchymal blush and arteriovenous shunting show numerous small vascular channels (v) outlined by azocarmine. The neuropile (arrowheads) is rarified (azocarmine stain, original magnification x100).
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