Head-to-head comparison of [18F]florbetapir and [18F]FDG PET for the early detection of amyloidosis in systemic amyloidosis and plasma cell dyscrasias

Purpose: Amyloidosis is underdiagnosed in light-chain amyloidosis (AL) and hereditary transthyretin amyloidosis (hATTR), as well as plasma cell dyscrasias (PCD). We aimed to investigate the utility of [18F]florbetapir (FBP) and [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) for the early detection and evaluation of organ involvement in systemic amyloidosis. Methods: We retrospectively included 83 participants, including 38 AL patients, 8 hATTR polyneuropathy patients, 28 PCD patients and 9 healthy controls. Whole-body PET/CT using [18F]FBP was performed in all participants, [18F]FDG PET was performed in 37 patients with AL and PCD, and the results were analyzed by visual and quantitative assessment. Biochemical, serum, and urine assays and histological analysis of tissue biopsies were performed. Results: [18F]FBP SUV and TBR analysis showed comparable uptake in AL and hATTR-PN patients (p.A117S, p.V50M, p.K55N, p.T69AM, or p.H76R mutation carriers) and greater uptake than in PCD patients and control patients. Different regional [18F]FBP and [18F]FDG distributions were observed among the PCD, AL, and hATTR-PN groups. Both [18F]FBP and [18F]FDG enabled the detection of amyloidosis in patients with PCD before clinical detection of AL. [18F]FBP SUV and visual analysis provide comparable measures of organ involvement and were comparable to [18F]FDG and clinical assessment. Conclusions: [18F]FBP PET detected organ amyloidosis in PCD, AL and hATTR-PN patients with high sensitivity and specificity and was more sensitive than [18F]FDG. Visual analysis and SUV analysis of [18F]FBP PET data provide comparable methods for evaluating organ involvement and are useful for noninvasively assisting in the early and accurate detection of systemic amyloidosis.