Relationship between suvmax values and malignancy of incidently detected thyroid lesions on FDG-PET imaging

Objective: The aim of this study was to evaluate the relationship between SUVmax values and malignancy in incidentally detected thyroid lesions on FDG-PET imaging. Methods: This retrospective study included 284 patients with incidental thyroid nodules detected during FDG-PET/CT imaging performed at Istanbul University-Cerrahpaşa Cerrahpaşa Faculty of Medicine between 2016-2023. The Maximum Standardized Uptake Value (SUVmax), laboratory findings, and pathology results of the nodules were compared. The patients were classified as malignant or benign according to both fine needle aspiration biopsy (FNAB) cytopathology results with the BETHESDA system and postoperative pathology results, and the relationship between SUVmax values and malignancy was evaluated. Results: The demographic data, nodule sizes, thyroid function tests, SUVmax values, FNAB and postoperative pathology results of the patients included in the study were analyzed. No significant relationship was found between SUVmax values and malignant/benign distinction in postoperative pathologies. As a result of FNAB, a cutoff value (≥12.125) was obtained, which can be evaluated as moderately sensitive and highly specific in distinguishing malignant from benign. Conclusion: SUVmax values in incidentally detected thyroid lesions on FDG-PET/CT imaging may serve as an important indicator for malignancy. However, histopathological confirmation remains essential for definitive diagnosis.