Comparison of 11C-4′-thiothymidine, 11C-methionine, and 18F-FDG PET/CT for the detection of active lesions of multiple myeloma

Abstract

PurposeThe aims of this study were to evaluate the possibility of using 11C-methionine (11C-MET) and 11C-4′-thiothymidine (11C-4DST) whole-body PET/CT for the imaging of amino acid metabolism and DNA synthesis, respectively, when searching for bone marrow involvement in patients with multiple myeloma (MM) and to compare these findings with those for 18F-FDG PET/CT and aspiration cytology.MethodsA total of 64 patients with MM, solitary plasmacytoma, monoclonal gammopathy of undetermined significance, or an unspecified diagnosis were prospectively enrolled. All the patients underwent three whole-body PET/CT examinations within a period of 1 week. First, the tracer accumulation was visually evaluated as positive, equivocal, or negative for 55 focal lytic lesions visualized using CT in 24 patients. Second, the percentages of marrow plasma cells as calculated using a bone marrow aspiration smear and tracer accumulation were evaluated in the posterior iliac crests of 36 patients.ResultsAmong the 55 lytic lesions, the 11C-MET and 11C-4DST findings tended to reveal more positive findings than the 18F-FDG findings. Based on the standard criteria for the diagnosis of active myeloma using the percentage of marrow plasma cells, significant differences were found between the 18F-FDG and 11C-MET findings and between the 18F-FDG and 11C-4DST findings, but no significant difference was observed between the 11C-MET and 11C-4DST findings.ConclusionThe addition of 11C-MET and 11C-4DST to 18F-FDG when performing PET/CT enabled clearer evaluations of equivocal lesions. Based on cytological diagnostic criteria, 11C-MET and 11C-4DST were more sensitive than 18F-FDG for the detection of active lesions. 11C-MET and 11C-4DST were more useful than 18F-FDG for the detection of active lesions, especially during the early stage of disease.

Nuclear medicine imaging of multiple myeloma, particularly in the relapsed setting

“…Once [11C]-4DST is incorporated into DNA, de-phosphorylation occurs relatively rarely, unlike [18 F]-FLT. This has also been shown in a study of MM patients in which [11C]-4DST showed more positive findings per patient than [18 F]-FDG-PET, particularly in patients with low numbers of bone marrow plasma cells (Table 2B) [25]. …”

“…Due to the active protein synthesis by the malignant plasma cells, this might also be a useful tracer for MM. In several studies, [11C]-MET was compared with [18 F]-FDG-PET (Table 2B) [25, 26]. Compared to [18 F]-FDG-PET, more lesions were detected with [11C]-MET, especially when a low number of aberrant plasma cells were present in the bone marrow (<30 %) [25].…”

“…In several studies, [11C]-MET was compared with [18 F]-FDG-PET (Table 2B) [25, 26]. Compared to [18 F]-FDG-PET, more lesions were detected with [11C]-MET, especially when a low number of aberrant plasma cells were present in the bone marrow (<30 %) [25]. A limitation for widespread use of [11C]-MET is the short half-life of approximately 20 minutes, necessitating production by an on-site cyclotron.…”

Positron Emission Tomography (PET) Radiopharmaceuticals in Multiple Myeloma

“…The main findings of the study were the following: firstly, the number of equivocal lesions observed using 18 F-FDG was larger compared to using 11 C-methionine or 11 C-4DST both before and after therapy. Secondly, 11 C-methionine and 11 C-4DST were superior to 18 F-FDG in clearly detecting skull lesions because of their low physiological accumulation in the brain [48].…”

Introduction of nuclear medicine research in Japan

“…Okasaki et al conducted a prospective study in an undeveloped medical field: a comparative study of the diagnostic evaluation of multiple myeloma (MM) using three different PET tracers, 18 F-fluorodeoxyglucose (FDG), an amino acid tracer 11 C-methionine (MET), and a tumour proliferation tracer 11 C-4′-thiothymidine (4DST) which has been recently introduced in Japan [1]. The progression of MM from care-not-required premalignant conditions, including monoclonal gammopathy of undetermined significance (MGUS) and smouldering MM (SMM), to care-required MM with end-stage organ damage requires clinical evaluation, but the diagnostic imaging for this purpose has not been established.…”