Evaluation of staging and early response to chemotherapy with whole-body diffusion-weighted MRI in malignant lymphoma patients: A comparison with FDG-PET/CT

BackgroundTo examine the utility of diffusion-weighted MRI (DW-MRI) for staging and early response to chemotherapy assessment in lymphoma patients as compared with fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). MethodsTwenty-eight patients with histologically confirmed malignant lymphoma underwent both MRI and FDG-PET/CT before (pretreatment) and after two courses of chemotherapy (mid-treatment). Staging with MRI (DW-MRI alone and with T2-weighted images) and FDG-PET was compared visually, and the concordance rate (kappa value, ) was calculated. To evaluate early response to chemotherapy, patients were divided into two groups, lesion-positive (LP) and lesion-negative (LN), based on a proposed original criterion. Progression-free survival (PFS) was compared between the groups using the Kaplan-Meier method. ResultsThe stage diagnosed with DW-MRI alone and with FDG-PET/CT was concordant in 22 patients (=0.71; P<0.05), and by adding T2-weighted images, the number of concordant patients increased to 26 (=0.90; P<0.05). On mid-treatment imaging, 19 patients were diagnosed as LN from both modalities. PFS differed significantly between LP and LN on both DW-MRI (P=0.0013) and FDG-PET/CT (P=0.037). ConclusionDW-MRI is a promising tool for staging and evaluation of early response to chemotherapy in patients with lymphoma. J. Magn. Reson. Imaging 2015;41:1601-1607. (c) 2014 Wiley Periodicals, Inc.