Purpose: This study aimed to compare the findings of magnetic resonance imaging (MRI) and F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) to differentiate reactive lymphadenitis from nodal lymphoma of the head and neck. Material and methods: This study included 138 patients with histopathologically confirmed cervical lymphadenopathy, including 35 patients with reactive lymphadenitis and 103 patients with nodal lymphoma, who had neck MRI ( = 63) and/or F-FDG-PET/CT ( = 123) before biopsy. The quantitative and qualitative MRI results and maximum standardised uptake value (SUV) were retrospectively analysed and compared between the 2 pathologies. Results: The maximum diameter (22.4 �� 6.9 vs. 33.3 �� 16.0 mm, < 0.01), minimum diameter (15.8 �� 3.6 vs. 22.3 �� 8.5 mm, < 0.01), and SUV (6.9 �� 2.7 vs. 12.8 �� 8.0, < 0.01) of the lesion were lower in reactive lymphadenitis than in nodal lymphoma, respectively. T2-hypointense-thickened capsules > 2 mm (46% vs. 14%, < 0.05) and T2-hypointense areas converging to the periphery (15% vs. 0%, < 0.05) were more frequently observed in reactive lymphadenitis than in nodal lymphoma, respectively. Hilum of nodes on T2-weighted images (54% vs. 22%, < 0.05) and diffusion-weighted images (69% vs. 30%, < 0.05) were more frequently demonstrated in reactive lymphadenitis than in nodal lymphoma, respectively. Conclusions: Reactive lymphadenitis had a smaller size and lower SUV. The presence of T2-hypointense-thickened capsules, T2-hypointense areas converging to the periphery, and hilum of nodes were signs of reactive lymphadenitis.
