Ante mortem amyloid imaging and β-amyloid pathology in a case with dementia with Lewy bodies

The association between ante mortem [ ¹¹C]-Pittsburgh Compound B (PiB) retention and β-amyloid (Aβ) load, Lewy body (LB) and neurofibrillary tangle (NFT) densities were investigated in a pathologically confirmed case of dementia with Lewy bodies (DLB). A 76 year old man presenting with a clinical diagnosis of DLB had undergone PiB-positron emission tomography (PET), ¹⁸F FDG-PET and magnetic resonance imaging (MRI) 18 months before death. The pathologic diagnosis was DLB neocortical-type with low-likelihood of Alzheimer's disease by NIA-Reagan criteria. Sections from regions of interest (ROI) on post-mortem examination were studied. A significant correlation was found between cortical Aβ density and PiB retention in the 17 corresponding ROIs (r = 0.899; p < 0.0001). Bielschowsky silver stain revealed mostly sparse neocortical neuritic plaques, whereas diffuse plaques were frequent. There was no correlation between LB density and PiB retention (r = 0.13; p = 0.66); nor between NFT density and PiB retention (r = -0.36; p = 0.17). The ROI-based analysis of imaging and histopathological data confirms that PiB uptake on PET is a specific marker for Aβ density, but cannot differentiate neuritic from diffuse amyloid plaques in this case with DLB.