Purpose18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is the reference standard in staging of 18F-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 18F-FDG PET/CT for lesion detection and initial staging in patients with aggressive or indolent lymphoma.Materials and methodsWe searched the MEDLINE, EMBASE, and CENTRAL databases for studies that compared WB-MRI with 18F-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 (μ) of WB-MRI and 18F-FDG PET/CT for initial staging and for assessing possible heterogeneity (χ2) across studies were calculated using commercially available software.ResultsEight studies comprising 338 patients were included. In terms of staging, the meta-analytic staging accuracies of WB-MRI and 18F-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 18F-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 18F-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%).ConclusionWB-MRI is a promising radiation-free imaging technique that may serve as a viable alternative to 18F-FDG PET/CT for staging of 18FDG-avid lymphomas, where 18F-FDG PET/CT remains the standard of care. Additionally, WB-MRI seems a less histology-dependent functional imaging test than 18F-FDG PET/CT and may be the imaging test of choice for staging of indolent NHLs with low 18F-FDG avidity.

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The characteristics of FDG uptake in the physiologic and malignant nasopharynx were investigated in the paper which was correlated with either pathologic findings or clinical follow-up. Three patients had pathologically established nasopharyngeal malignancy. In the 3 nasopharyngeal malignancies, 2 had diffusely and expansively increased FDG uptake, and one had asymmetric uptake. Our results indicated that the difference between adenoid hypertrophy and malignancy is asymmetric or diffusely expansive 18F-FDG uptake with or without correlating morphologic lesion on diagnostic CT in children under 10 years of age. The typical characteristics of physiologic and inflammatory 18F-FDG uptake in nasopharynx are symmetrically trapezoid. Diffusely increased nasopharyngeal FDG uptake can be considered physiologic if SUVmax is less than 7.6 but should be carefully assessed by pharyngorhinoscopy if SUVmax is greater than 11 and there is no correlating morphologic lesion on diagnostic CT. The diffusely, expansively increased uptake, and asymmetric uptake in particular, should be considered as malignancy. Further biopsy is especially indicated in patients with retropharyngeal space and bilateral cervical lymph node abnormality but no history of malignancy.

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