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Theranostics 2017; 7(11):2956-2964. doi:10.7150/thno.20491

Research Paper

¹¹C-Methionine-PET in Multiple Myeloma: A Combined Study from Two Different Institutions

Constantin Lapa^1*✉, Maria J. Garcia-Velloso^2*, Katharina Lückerath¹, Samuel Samnick¹, Martin Schreder³, Paula Rodriguez Otero², Jan-Stefan Schmid¹, Ken Herrmann^1,4, Stefan Knop³, Andreas K. Buck¹, Hermann Einsele³, Jesus San-Miguel^2#, Klaus Martin Kortüm^3#

1. University Hospital Würzburg, Department of Nuclear Medicine, Würzburg, Germany
2. Clinica Universidad de Navarra, Center of Applied Medical Research, Navarra Institute for Health Research (CIMA). IDISNA, Pamplona, Spain
3. University Hospital Würzburg, Department of Hematology and Oncology, Würzburg, Germany
4. University Hospital Essen, Department of Nuclear Medicine, Essen, Germany
* equal contribution
# equal contribution

Abstract

¹¹C-methionine (MET) has recently emerged as an accurate marker of tumor burden and disease activity in patients with multiple myeloma (MM). This dual-center study aimed at further corroboration of the superiority of MET as positron emission tomography (PET) tracer for staging and re-staging MM, as compared to ¹⁸F-2`-deoxy-2`-fluoro-D-glucose (FDG).

78 patients with a history of solitary plasmacytoma (n=4), smoldering MM (SMM, n=5), and symptomatic MM (n=69) underwent both MET- and FDG-PET/computed tomography (CT) at the University Centers of Würzburg, Germany and Navarra, Spain. Scans were compared on a patient and on a lesion basis. Inter-reader agreement was also evaluated. In 2 patients, tumor biopsies for verification of discordant imaging results were available.

MET-PET detected focal lesions (FL) in 59/78 subjects (75.6%), whereas FDG-PET/CT showed lesions in only 47 patients (60.3%; p<0.01), accordingly disease activity would have been missed in 12 patients. Directed biopsies of discordant results confirmed MET-PET/CT results in both cases.

MET depicted more FL in 44 patients (56.4%; p<0.01), whereas in two patients (2/78), FDG proved superior. In the remainder (41.0%, 32/78), both tracers yielded comparable results. Inter-reader agreement for MET was higher than for FDG (κ = 0.82 vs κ = 0.72).

This study demonstrates higher sensitivity of MET in comparison to standard FDG to detect intra- and extramedullary MM including histologic evidence of FDG-negative, viable disease exclusively detectable by MET-PET/CT. MET holds the potential to replace FDG as functional imaging standard for staging and re-staging of MM.

Keywords: PET/CT, ¹¹C-methionine, multiple myeloma, FDG.