Diagnostic Sensitivity of [18F]-Florbetaben-PET/CT in Detecting Cardiac Involvement in AL Amyloidosis

Abstract

Background Early detection of cardiac involvement in light-chain (AL) amyloidosis remains challenging despite its prognostic importance. [18F]-florbetaben positron emission tomography/computed-tomography (F-PET) shows promise for amyloid detection. Objectives The authors report results from the prospective MoRBiDA (Molecular, magnetic resonance, and echocardiographic imaging combined with biomarkers of cardiac and clonal disease to predict survival and assess response to therapy in cardiac AL amyloidosis) study integrating multimodality imaging in treatment-naive AL amyloidosis patients to evaluate F-PET diagnostic sensitivity and correlations with established markers. Methods Patients with suspected cardiac involvement underwent baseline echocardiography, cardiac magnetic resonance (CMR), and F-PET. Cardiac involvement was defined by consensus criteria. F-PET included 50-minute dynamic cardiac acquisition (static reconstructions at ∼15 and 50-min postinjection), delayed static scan at 110 min, and myocardial tracer retention. Positive uptake was defined by visual myocardial retention exceeding blood-pool/background plus quantitative mean and maximum standardized uptake value. Results Of the 28 enrolled patients, 25 had cardiac involvement (3 patients without cardiac involvement had no myocardial-uptake). Early and late F-PET uptake (15-50 min) was present in all 25. Delayed uptake (110 min) was absent in 4/25 (84% sensitivity); these showed retention up to 50-min with typical CMR findings. F-PET parameters correlated moderately with N-terminal pro–B-type natriuretic peptide (standardized uptake value rho = 0.40-0.54, P < 0.05) and echocardiographic global longitudinal strain (myocardial tracer retention rho = 0.70, P < 0.001) but not with CMR-derived extracellular volume. Conclusions Early-to-late F-PET demonstrates excellent sensitivity for cardiac AL amyloidosis. Delayed (110-min) retention is not universal, indicating variable washout kinetics that limits its discriminatory value for amyloid typing vs late imaging or multiorgan analysis. Extracellular volume may not fully capture amyloid burden. These findings complement recent multicentric data and support further studies on optimal timing and volumetric metrics.