[¹¹C]-メチオニンPET/CTによる骨髄浸潤の評価と多発性骨髄腫の予後予測因子としての利用

To evaluate the prognostic utility of a novel quantitative imaging metric, whole-body metabolic burden (WB-MB), derived from [¹¹C]-Methionine PET/CT, in patients with multiple myeloma (MM), and to assess its correlation with clinical biomarkers and survival outcomes.

In this prospective, single-center study, 34 patients with biopsy-confirmed MM underwent whole-body [¹¹C]-Methionine PET/CT for staging or restaging. WB-MB was calculated using a semi-quantitative method incorporating both the extent and intensity of methionine uptake across 12 anatomical regions. Liver- and aorta-normalized WB-MB ratios (WB-MB/liver and WB-MB/aorta) were also computed. Correlations with laboratory biomarkers were analyzed using regression models, and prognostic performance was assessed through Kaplan-Meier survival analysis and hazard ratios for progression-free survival (PFS) and overall survival (OS).

WB-MB showed significant inverse correlation with hemoglobin and positive correlations with LDH, beta-2 microglobulin (B2M), and serum kappa free light chain levels. No significant associations were observed with platelet count, WBC, or lambda light chains. WB-MB, WB-MB/liver, and WB-MB/aorta were all significantly associated with OS and PFS (p < 0.05), while maximum SUVmean was not. A WB-MB threshold of 164.79 was identified as predictive for PFS. Notably, no deaths occurred in patients with WB-MB < 101 during follow-up.

WB-MB scoring with [¹¹C]-Methionine PET/CT is a promising, reproducible imaging biomarker for evaluating disease burden and prognosis in MM. It correlates with key laboratory markers and outperforms static SUV-based metrics in predicting survival outcomes. Further multicenter studies are needed to validate these findings and explore integration into therapeutic decision-making.