Association Between Computed Tomography Characteristics and Ultrasound-Based Risk Stratification in Incidental Thyroid Nodules of Oncologic Patients

Abstract

Background: Incidental thyroid nodules (ITNs) are frequently detected in oncologic patients undergoing computed tomography (CT). However, the diagnostic accuracy of CT for these nodules, particularly in comparison with ultrasound-based Thyroid Imaging Reporting and Data System (TIRADS) and Korean Thyroid Imaging Reporting and Data System (K-TIRADS) classifications, remains unclear. Objectives: We evaluated the diagnostic accuracy of CT for characterizing high-risk sonographic patterns in ITNs in oncologic patients by comparing CT findings with ultrasound-based classifications. Methods: This retrospective study analyzed 420 oncologic patients who underwent contrast-enhanced chest CT. Of the 65 patients with ITNs, 55 were included in the final analysis, comprising 81 nodules. CT findings, including density, enhancement, calcification, and size, were compared with the TIRADS and K-TIRADS ultrasound classifications. Fine-needle aspiration (FNA) was performed when indicated according to the K-TIRADS criteria. Statistical analyses included the intraclass correlation coefficient (ICC), chi-squared tests, logistic regression, and receiver operating characteristic (ROC) curve analysis. Results: ROC analysis of enhancement-based prediction yielded an area under the curve of 0.86 (95% CI, 0.78 - 0.94) for K-TIRADS and 0.88 (95% CI, 0.80 - 0.94) for TIRADS. The optimal enhancement threshold for high-risk sonographic patterns was 38.8 Hounsfield units (HU). Diagnostic accuracy was 80.0% (95% CI, 69.0%-88.0%) for K-TIRADS and 78.0% (95% CI, 68.0%-87.0%) for TIRADS. Calcification was significantly associated with both TIRADS (P < 0.01) and K-TIRADS (P = 0.04). CT and ultrasound measurements of nodule size were strongly correlated (ICC = 0.96; P < 0.001). Follicular adenoma was the most common final diagnosis after FNA (63.2%). Conclusions: CT enhancement and calcification patterns provide complementary diagnostic value for ITNs in oncologic patients and may facilitate more targeted management. However, ultrasound remains essential for evaluating high-risk patterns. These findings suggest that CT may serve as a useful adjunct in ITN triage.