Fluorodeoxyglucose positron emission tomography in multiple myeloma, solitary plasmocytoma and monoclonal gammapathy of unknown significance.

The aim of our study was to evaluate the role of fluorine-18 fluorodeoxyglucose positron emission tomography (FDGPET) in 49 patients with plasma cell malignancies. FDG-PET results were verified by conventional imaging methods, including plain radiographs, magnetic resonance imaging (MRI) and computer tomography (CT). Focally increased FDG uptake was observed in three (23 %) of 11 newly diagnosed myeloma patients with negative bone radiographs. Focally increased tracer uptake was found in five of 26 patients with MM in remission but with suspected relapse. Of the 20 patients who had negative FDG-PET scans, only one relapsed 12 months after FDG-PET examination.. FDG-PET was positive in two of six patients with MGUS and with suspected progression to MM or with suspected other malignancy. In one case a thyroid carcinoma was later detected, in the other an intestinal tumor was found. We conclude that FDG PET might contribute to initial staging of MM patients with negative bone radiographs and is useful for the follow-up of patients in remission especially in non-secretory MM and in patients with large plasmocytoma (>5 cm) after radiochemotherapy.