Diffusion-weighted magnetic resonance imaging compared with fluoro-deoxy-glucose positron emission tomography-computed tomography for assessment in lymphoma

Purpose. - Diffusion weighted MRI (DW-MRI) sequences appear as a promising functional technique supplementary to morphologic MRI for oncology purposes. We evaluated the results of DW-MRI for the staging of lymphomas, compared to FDG PET/CT. Methods. - Twenty-seven patients with lymphoma referred for FDG PET/CT (initial staging, relapse or treatment evaluation) were prospectively included. They underwent MRI including free breathing DW and T2 weighted imaging. Lymph node areas and organs involvement were listed for each modality and compared using Cohen's kappa (kappa) test. MRI performances were evaluated using FDG PET as the gold standard. The results of PET and MRI were compared (with respect to the final staging by the haematologist). Results. - Regarding the lymph nodes, 154 involved areas were detected by MRI out of the 184 detected by PET, that is an excellent concordance (kappa = 0.87), sensitivity of 0.84 and specificity of 1. Concordance and sensitivity were inferior for extranodal disease (notably bone lesions) with 27 lesions detected by MRI out of the 40 viewed with PET. Regarding pre-treatment evaluation, two patients were understaged both with PET and MRI (bone marrow involvement); assessment of stage was concordant for both modalities in 18 patients out of 21. Conclusions. - Performance of MRI including DW images was close to that of FDG PET/CT for lymph node areas involvement. Further studies are needed to assess its sensitivity for extranodal lesions, and its accuracy for determining the stage of the disease. (c) 2012 Elsevier Masson SAS. All rights reserved.