11C-PiB PET Imaging of Encephalopathy Associated with Cerebral Amyloid Angiopathy

We herein report that the clinical, laboratory, and radiographic features and positron emission tomography (PET) imaging may provide valuable clues to the pathogenesis of cerebral amyloid angiopathy (CAA)-associated encephalopathy, which currently remains unclear. We herein describe two cases of encephalopathy with CAA, with an emphasis on PET imaging with 11C-Pittsburgh compound B (11C-PiB) and 18F-fluorodeoxyglucose (18F-FDG). One case of Alzheimer's disease for which a brain biopsy was performed showed CAA-related inflammation. Another case that had developed sudden sensory aphasia presented with posterior reversible encephalopathy syndrome-like vasogenic edema in the left temporal region with 11C-PiB uptake and microhemorrhages. 11C-PiB and 18F-FDG PET are useful for detecting CAA-associated encephalopathy, including atypical CAA cases.