Association of SUVmax with Malignancy in Focal FDG-Avid Thyroid Incidentalomas

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Öztop H., Hunutlu F. Ç., İşleyen Çolak E., Bilgiç S., Şahin A. B., Öz Gül Ö.

Uludağ Üniversitesi Tıp Fakültesi Dergisi, cilt.52, sa.1, ss.1, 2026 (TRDizin)

Özet

Thyroid incidentalomas (TIs) detected on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) are associated with an increased risk of malignancy, particularly in the presence of focal FDG uptake. While quantitative PET/CT parameters, such as the maximum standardized uptake value (SUVmax), have been extensively studied, current management guidelines primarily rely on nodule size and ultrasonographic features. This study aimed to evaluate whether PET/CT-derived radiological parameters provide additional information for malignancy in FDG-avid TIs. This retrospective single-center study included patients with focal FDG-avid thyroid incidentalomas detected on PET/CT who underwent ultrasonographic evaluation and cytological and/or histopathological confirmation. Demographic characteristics, metabolic parameters derived from PET/CT scans, ultrasonographic findings and anatomical localization were documented. Benign and malignant lesions were compared. Receiver operating characteristic (ROC) analysis was conducted to determine the optimal SUVmax cut-off value and logistic regression analyses were employed to identify variables independently associated with malignancy. A total of 53 patients were included, with 13 (24.5%) having malignant thyroid lesions. Malignant nodules demonstrated significantly higher SUVmax values than benign nodules (p=0.008). ROC analysis established a SUVmax cut-off value of 5.8 for discrimination between benign and malignant nodules (AUC: 0.748). Isthmus localization also remained significant in multivariate analysis (p=0.037). No other morphologic or ultrasonographic parameters were significant. In cases of focal FDG-avid TIs, an SUVmax value of ≥5.8 is associated with an increased risk of malignancy and may provide complementary information in risk stratification. However, SUVmax should be interpreted alongside clinical and ultrasonographic findings, not as a standalone decision-making tool.