Additional detection of Bethesda greater than or equal to III cytology in cold thyroid nodules beyond American College of Radiology Thyroid Imaging Reporting and Data System risk stratification

Background Cold thyroid nodules identified on nuclear medicine scintigraphy have historically been associated with increased malignancy risk. However, contemporary practice relies primarily on ultrasound risk stratification systems such as the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) to guide fine needle aspiration (FNA). The additional value of scintigraphy beyond ultrasound risk stratification remains uncertain. Aim To determine whether scintigraphy identifies nodules with Bethesda greater than or equal to III cytology beyond ACR TI-RADS FNA criteria. Methods A retrospective review of thyroid nodules undergoing ultrasound, nuclear medicine scintigraphy, and FNA was performed. Nodules with reduced uptake were classified as cold nodules. Cytology was classified using the Bethesda System, with Bethesda greater than or equal to III considered clinically significant. Results A total of 235 cold thyroid nodules were identified. Of these, 169 met ACR TI-RADS FNA criteria, with 34 (20.1%) demonstrating Bethesda greater than or equal to III cytology. Sixty-six nodules below TI-RADS FNA thresholds underwent FNA because of cold scintigraphic findings, of which seven (10.6%) demonstrated Bethesda greater than or equal to III cytology. Overall, seven of 41 nodules (17.1%) with Bethesda greater than or equal to III cytology were identified solely because of scintigraphic appearance. Conclusion Most Bethesda greater than or equal to III cytology occurred in nodules already meeting ACR TI-RADS FNA criteria. Cold scintigraphy identified few additional nodules below ultrasound FNA thresholds, suggesting limited additional detection beyond ultrasound risk stratification.