Predictive parameters in differentiating physiological uptakes from pathological uptakes of palatine tonsil on PET/CT in patients with lymphoma

The purpose of this study was to distinguish physiological uptakes from pathological uptakes of the palatine tonsil (PT) in patients with lymphoma using positron emission tomography (PET)/computed tomography (CT) parameters, including standardized uptake value (SUV), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and carotid-tonsil SUVmax difference and ratio. We also aimed to investigate cutoff values for tonsillar lymphoma (TL), which was confirmed histopathologically. Medical charts of 45 patients undergoing diagnostic palatine tonsillectomy between 2022 and 2025 were prospectively reviewed. Tonsillectomy was performed for increased 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) uptakes in PT on PET/CT during regular follow-ups of patients with lymphoma. The PTs following tonsillectomy were sent for histopathological examination. SUV, MTV, and TLG were calculated for both groups, and these values for the groups were compared with each other. The common carotid artery was accepted as a reference point for SUVmax in both groups. The reference common carotid artery was chosen on the opposite side of the more evident FDG uptake on PET/CT. TL had higher SUVmax ( P  < .001), TLG ( P  < .01), and MTV ( P  < .01) as compared with PT with physiological uptakes. FDG involvement patterns for physiological uptakes were seen as focal in 8, diffuse in 9, and coin-shaped in 12 patients, whereas those for TL were seen as coin-shaped in 1, diffuse in 6, and ring-shaped in 9 patients ( P  < .001). Apart from SUVmax, TLG and MTV values may be added to the preoperative scanning parameters to increase specificity and to accurately differentiate physiological uptakes of PT from TL. MTV >3.48 may be more helpful for specifying TL, with 88.2% sensitivity and 91.3% specificity.