Abstract
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Objectives We developed and implemented a novel analytical approach to cerebral binding of [11C]Pittsburgh compound-B (PiB).
Methods We employed T1-weighed MRI and Neurostat software to identify cerebral surface gray matter voxels. These locations were then sampled from co-registered PiB scans, resulting in surface projection maps of amyloid binding. Analyses were performed in 28 subjects with clinically-defined probable Alzheimer disease (AD), 8 with dementia with Lewy bodies (DLB), 7 with frontotemporal dementia (FTD) and 4 with Parkinson disease with dementia (PDD). All subjects had concordant clinical classifications and qualitative results of imaging with [11C]PiB to define amyloid deposition and [11C]dihydrotetrabenazine to define nigrostriatal projection density.
Results The pattern of PiB deposition in AD revealed highest binding in the frontal lobe and the posterior cingulate / precuneous cortices. Less intense elevated binding was found in the temporal and parietal association cortices. Lowest PiB binding was present in the primary somatomotor and occipital cortices. This same pattern of elevated PiB binding was observed in PiB-positive DLB and PDD subjects. Subjects with FTD and PiB-negative DLB revealed no areas of increased cortical binding. An additional group of clinically-diagnosed FTD subjects, but with elevated cortical PiB binding, revealed a pattern identical to that of AD.
Conclusions A canonical pattern of distribution and intensity of PiB binding occurs in subjects with neurodegenerative dementia, regardless of clinical diagnosis, when cortical PiB binding is elevated. Surface projection maps generated in this analysis offer a simple and robust data display, permitting rapid recognition of amyloid deposition patterns, and its use may facilitate standardization of clinical research image classification with PiB. This surface mapping approach may also be valuable in clinical patient classifications with emerging 18F-labeled amyloid imaging agents.
Research Support USPHS P01 NS15655, USPHS P50 AG0086