Head-to-Head Comparison between FDG and 11C-Methionine in Multiple Myeloma: A Systematic Review

Abstract

The aim of this systematic review is to provide a comprehensive overview of the existing literature, comparing ¹⁸F-fluorodeoxyglucose (FDG) and ¹¹C-methionine (MET) for the imaging of multiple myeloma (MM) with positron emission computed tomography (PET/CT). Relevant studies published from 2013 up to March 2023 were selected by searching Scopus, PubMed, and Web of Science. Selected imaging studies were analyzed using a modified version of the critical Appraisal Skills Programme (CASP). Ten studies encompassing 335 patients were selected. On a patient-based analysis, MET sensitivity ranged between 75.6% and 100%, resulting higher than that measured for FDG (0-100%). MET outperformed FDG for the detection of focal lesions, diffuse bone marrow involvement and mixed patterns. PET-derived parameters resulted higher for MET than for FDG, with a strong correlation with clinical variables (e.g., monoclonal component and beta-2-microglobulin levels, bone marrow infiltration, etc.), although FDG maintained a prognostic impact on outcome prediction. When compared to other tracers or imaging modalities, MET showed stronger correlation and inter-observer agreement than FDG. Although biased by the small cohorts and requiring confirmation through multicenter studies, preliminary findings suggest that MET-PET should be preferred to FDG for PET imaging of MM, or alternatively used as a complementary imaging modality. Some issues, such as tracer availability and the role of MET with respect to other emerging tracers (i.e., ⁶⁸Ga-pentixafor, ¹⁸F-FACBC and ¹⁸F-FET), should be the topic of further investigations.

Keywords: PET/CT; amino-acid; choline; molecular imaging; multiple myeloma.

Figure 1

Schematic representation of PRISMA workflow for manuscripts’ selection.

Figure 2

Quality appraisal of selected articles using CASP checklist for diagnostic studies [14,15,16,17,18,19,20,21,22,23].

Figure 3

60-year-old male. Pathological fracture in C6. Bone marrow biopsy was compatible with multiple myeloma. (upper row) Baseline FDG PET/MR demonstrated the presence of multiple focal uptake in the bones, without extranodal involvement, corresponding to an increase of signal at DWI images. After induction chemotherapy (lower row), FDG PET/MR demonstrated no uptake in the site of pre-existing lesions, with the persistence of a slight signal at DWI images. Therefore, FDG–PET was conclusive for the presence of non-viable tissue.