11C-Acetate PET/CT for metabolic characterization of multiple myeloma: A comparative study with 18F-FDG PET/CT

Abstract

We prospectively compared 11C-acetate with 18F-FDG in a PET/CT evaluation of multiple myeloma (MM), specifically on diagnostic accuracy, identification of high-risk patients, and monitoring of treatment response. Methods: Dual-tracer PET/CT was performed on 35 pathologically and clinically confirmed and untreated patients (26 with symptomaticMM,5 with smolderingMM,and 4 with monoclonal gammopathy of unknown significance) and 20 individuals with normal marrow. Results: 11C-acetate showed significant incremental value over 18F-FDG (84.6% vs. 57.7%) for positively identifying patients with diffuse and focal symptomatic MM, and was negative in patients with indolent smoldering MM and monoclonal gammopathy of unknown significance. Three functional parameters-number of 11Cacetate- avid and 18F-FDG-avid focal bone lesions and 11C-acetate general marrow activity-strongly correlated with β-2-microglobulin as surrogate imaging markers of tumor burden. After induction chemotherapy, the metabolic change in 11C-acetate general marrow activity correlated with clinical response. Conclusion: Metabolic characterization ofMMin diagnosis, risk stratification, and treatmentmonitoring can be done more accurately by assessing lipid metabolismwith 11C-acetate than by assessing glucose metabolism with 18F-FDG. © 2014 by the Society of Nuclear Medicine and Molecular Imaging, Inc.