Neuroimaging correlates with neuropathologic schemes in neurodegenerative disease

Introduction: Neuroimaging biomarkers are important for early diagnosis of Alzheimer's disease, and comparing multimodality neuroimaging to autopsy data is essential. Methods: We compared the pathologic findings from a prospective autopsy cohort (n = 100) to Pittsburgh compound B PET (PiB-PET), ¹⁸F-fluorodeoxyglucose PET (FDG-PET), and MRI. Correlations between neuroimaging biomarkers and neuropathologic schemes were assessed. Results: PiB-PET showed strong correlations with Thal amyloid phase and Consortium to Establish a Registry for Alzheimer's Disease score and categorized 44% of Thal phase 1 participants as positive. FDG-PET and MRI correlated modestly with Braak tangle stage in Alzheimer's type pathology. A subset of participants with “none” or “sparse” neuritic plaque scores had elevated PiB-PET signal due to diffuse amyloid plaque. Participants with findings characterized as “suspected non-Alzheimer's pathophysiology” represented 15% of the group. Discussion: PiB-PET is associated with Alzheimer's disease, neuritic plaques, and diffuse plaques. FDG-PET and MRI have modest correlation with neuropathologic schemes. Participants with findings characterized as suspected non-Alzheimer's pathophysiology most commonly had primary age-related tauopathy.