Diagnostic accuracy of TI-RADS in the diagnosis of Thyroid Nodules, keeping Ultrasound-Guided FNAC as the Gold Standard

Abstract

Background: To determine the diagnostic accuracy of Thyroid Imaging Reporting and Data System (TI-RADS) in predicting thyroid malignancy using ultrasound-guided fine needle aspiration cytology (FNAC) as the gold standard.

Methodology: This retrospective cross-sectional study was conducted from August 2019 to April 2025 at the Interventional Radiology Department of Rehman Medical Institute. The study included 424 patients with thyroid nodules who underwent ultrasound evaluation using TI-RADS classification followed by ultrasound-guided FNAC. Statistical analysis was performed to calculate sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy.

Results: The overall sensitivity and specificity of TI-RADS were 54.55% and 75.79%, respectively, with PPV of 20.69% and NPV of 93.51%. The risk of malignancy for TI-RADS categories 3, 4, and 5 were 22.7%, 29.16%, and 86.66%, respectively. TI-RADS 2 demonstrated high specificity (98.2%), while TI-RADS 5 showed perfect sensitivity (100%). A significant association was found between TI-RADS scores and Bethesda classification (P < 0.001), with an area under the curve of 0.932.

Conclusion: TI-RADS is a useful tool for thyroid nodule evaluation, particularly in high-risk categories. However, the moderate overall accuracy highlights the need for larger multicenter studies to improve generalizability and reduce interobserver variability.