18F-FDG PET, the early phases and the delivery rate of 18F-AV45 PET as proxies of cerebral blood flow in Alzheimer's disease: Validation against 15O-H2O PET

Abstract

IntroductionDual-biomarker positron emission tomography (PET), providing complementary information on cerebral blood flow and amyloid-β deposition, is of clinical interest for Alzheimer's disease (AD). The purpose of this study was to validate the perfusion components of early-phase 18F-florbetapir (eAV45), the 18F-AV45 delivery rate (R1), and 18F-FDG against 15O-H2O PET and assess how they change with disease severity. MethodsThis study included ten controls, 19 amnestic mild cognitive impairment, and 10 AD dementia subjects. Within-subject regional correlations between modalities, between-group regional and voxel-wise analyses of covariance per modality, and receiver operating characteristic analyses for discrimination between groups were performed. ResultsFDG standardized uptake value ratio, eAV45 (0–2 min) standardized uptake value ratio, and AV45-R1 were significantly associated with H2O PET (regional Pearson r = 0.54–0.82, 0.70–0.94, and 0.65–0.92, respectively; P < .001). All modalities confirmed reduced cerebral blood flow in the posterior cingulate of patients with amnestic mild cognitive impairment and AD dementia, which was associated with lower cognition (r = 0.36–0.65, P < .025) and could discriminate between patient and control groups (area under the curve > 0.80). However, eAV45 was less sensitive to reflect the disease severity than AV45-R1 or FDG. DiscussionR1 is preferable over eAV45 for accurate representation of brain perfusion in dual-biomarker PET for AD.