Comparison between whole-body diffusion MRI and 18FDG PET/CT in the diagnosis of symptomatic myeloma

Introduction. - Our work aims to compare whole-body diffusion MRI (DWMRI) and (18)FDG PET/CT in the diagnosis of symptomatic myeloma. Patients and method. - From November 2008 till May 2010, 19 patients were investigated by DWMRI and by (18)FDG PET/CT. The patients were classified according to the criteria of the International Myeloma Working Group in eight non-symptomatic myelomas and 11 symptomatic myelomas. The sensitivity and the specificity of two methods of imaging were studied by retaining the presence or the absence of a diffuse infiltration (ID), focal lesions (FL), or both parameters (FL + ID), in both modalities of imaging. We compared the concordance between two techniques for every patient by using these signs using a weighted kappa test. Results. - The performances of both modalities seem comparable, with superior diagnostic performances for the FL (Se = 100% and Sp = 75% in DWMRI and Se = 91% and Sp = 75% for (18)FDG PET/CT). By combining both parameters, the (18)FDG PET/CT seems more specific, but the sensitivity is comparable in both modalities (Se = 100% in MRI and Se = 100% in (18)FDG PET/CT; Sp = 37% in DWMRI and Sp = 62% for (18)FDG PET/CT). The concordance between both techniques is better by taking into account the FL than the other parameters (weighted kappa = 0.61 for FL, 0.5 for the FL + ID and 0.16 for ID alone). Conclusion. - Diagnostic performances of whole-body diffusion MRI and (18)FDG PET/CT seem equivalent, but concordance between both techniques is imperfect. Further studies are necessary to understand this discrepancy. (C) 2012 Elsevier Masson SAS. All rights reserved.