Whole-body MRI versus 18 F-FDG PET/CT for pretherapeutic assessment and staging of lymphoma: a meta-analysis

F-fluorodeoxyglucose ( F-FDG) positron emission tomography/computed tomography (PET/CT) is the reference standard in staging of F-FDG-avid lymphomas; however, there is no recommended functional imaging modality for indolent lymphomas. Therefore, we aimed to compare the performance of whole-body magnetic resonance imaging (WB-MRI) with that of F-FDG PET/CT for lesion detection and initial staging in patients with aggressive or indolent lymphoma. We searched the MEDLINE, EMBASE, and CENTRAL databases for studies that compared WB-MRI with F-FDG PET/CT for lymphoma staging or lesion detection. The methodological quality of the studies was assessed using version 2 of the "Quality Assessment of Diagnostic Accuracy Studies" tool. The pooled staging accuracy ( ) of WB-MRI and F-FDG PET/CT for initial staging and for assessing possible heterogeneity ( ) across studies were calculated using commercially available software. Eight studies comprising 338 patients were included. In terms of staging, the meta-analytic staging accuracies of WB-MRI and F-FDG PET/CT for Hodgkin lymphoma and aggressive non-Hodgkin lymphoma (NHL) were 98% (95% CI, 94%-100%) and 98% (95% CI, 94%-100%), respectively. The pooled staging accuracy of F-FDG PET/CT dropped to 87% (95% CI, 72%-97%) for staging in patients with indolent lymphoma, whereas that of WB-MRI remained 96% (95% CI, 91%-100%). Subgroup analysis indicated an even lower staging accuracy of F-FDG PET/CT for staging of less FDG-avid indolent NHLs (60%; 95% CI, 23%-92%), in contrast to the superior performance of WB-MRI (98%; 95% CI, 88%-100%). WB-MRI is a promising radiation-free imaging technique that may serve as a viable alternative to F-FDG PET/CT for staging of FDG-avid lymphomas, where F-FDG PET/CT remains the standard of care. Additionally, WB-MRI seems a less histology-dependent functional imaging test than F-FDG PET/CT and may be the imaging test of choice for staging of indolent NHLs with low F-FDG avidity.