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 (11)C-Pittsburgh compound B ((11)C-PiB) and (18)F-fluorodeoxyglucose ((18)F-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 (11)C-PiB uptake and microhemorrhages. (11)C-PiB and (18)F-FDG PET are useful for detecting CAA-associated encephalopathy, including atypical CAA cases.