18 F-FDG and 11 C-Methionine PET/CT in Newly Diagnosed Multiple Myeloma Patients: Comparison of Volume-Based PET Biomarkers
Maria I Morales-Lozano (1) , Oliver Viering (2) , Samuel Samnick (2) , Paula Rodriguez-Otero (3) , Andreas K Buck (2) , Maria Marcos-Jubilar (3) , Leo Rasche (4), Elena Prieto (1) , K Martin Kortüm (4) , Jesus San-Miguel (3) , Maria J Garcia-Velloso (1) , Constantin Lapa (2, 5)
11C-methionine (11C-MET) is a new positron emission tomography (PET) tracer for the assessment of disease activity in multiple myeloma (MM) patients, with preliminary data suggesting higher sensitivity and specificity than 18F-fluorodeoxyglucose (18F-FDG). However, the value of tumor burden biomarkers has yet to be investigated.
Our goals were to corroborate the superiority of 11C-MET for MM staging and to compare its suitability for the assessment of metabolic tumor burden biomarkers in comparison to 18F-FDG.
Twenty-two patients with newly diagnosed, treatment-naïve symptomatic MM who had undergone 11C-MET and 18F-FDG PET/CT were evaluated. Standardized uptake values (SUV) were determined and compared with total metabolic tumor volume (TMTV) for both tracers: total lesion glycolysis (TLG) and total lesion 11C-MET uptake (TLMU). PET-derived values were compared to Revised International Staging System (R-ISS), cytogenetic, and serologic MM markers such as M component, beta 2 microglobulin (B2M), serum free light chains (FLC), albumin, and lactate dehydrogenase (LDH). In 11 patients (50%), 11C-MET detected more focal lesions (FL) than FDG (p < 0.01).
SUVmax, SUVmean, SUVpeak, TMTV, and TLMU were also significantly higher in 11C-MET than in 18F-FDG (p < 0.05, respectively). 11C-MET PET biomarkers had a better correlation with tumor burden (bone marrow plasma cell infiltration, M component; p < 0.05 versus p = n.s. respectively).
This pilot study suggests that 11C-MET PET/CT is a more sensitive marker for the assessment of myeloma tumor burden than 18F-FDG. Its implications for prognosis evaluation need further investigation.