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Figure 9. Hyperperfusion syndrome after carotid endarterectomy. The patient developed neurologic symptoms referable to the left hemisphere several days after undergoing a left carotid endarterectomy. The CT scan was abnormal, and the question of infarction was raised. Left: Transverse fast spin-echo T2-weighted MR image (4,000/104; echo train length, eight; matrix, 256 x 192; field of view, 200 x 200 mm, section thickness, 5 mm with 1-mm gap; one signal acquired) demonstrates numerous areas of abnormal high signal intensity (arrow) in the left hemisphere. Infarctions remained in the differential diagnosis. Middle: Transverse DW MR image (b = 1,000 sec/mm2; effective gradient, 14 mT/m; 6,000/108; matrix, 256 x 128; field of view, 400 x 200 mm; section thickness, 6 mm with 1-mm gap) reveals predominant isointensity in the left hemisphere with small areas of slight hypointensity and slight hyperintensity (arrow). ADC images (not shown) demonstrated no areas of restricted diffusion. Right: Transverse three-dimensional time-of-flight MR angiogram (49/6.9; 20° flip angle; matrix, 256 x 192; field of view, 200 x 200 mm; section thickness, 1 mm) demonstrates excellent flow-related enhancement (arrow) in the left hemisphere. A diagnosis of hyperperfusion syndrome with vasogenic edema was established on the basis of DW imaging findings. The patient was treated conservatively and recovered fully.
