Combined Diagnostic Utility of ACR-TIRADS, Fine Needle Aspiration Cytology and Histopathology in the Evaluation of Thyroid Nodules: A Prospective Study

Abstract

Background: Thyroid nodules are a common clinical problem, with malignancy occurring in approximately 4.5–6.5% of cases. High-resolution ultrasonography, combined with the American College of Radiology–Thyroid Imaging Reporting and Data System (ACR-TIRADS), has emerged as an effective tool for stratifying malignancy risk and guiding the need for fine-needle aspiration cytology (FNAC). Despite its increasing use, limited Indian data exist correlating ACR-TIRADS scores with final histopathology.

Aim: To evaluate the combined diagnostic performance and correlation of ACR-TIRADS, Fine Needle Aspiration Cytology (FNAC), and histopathological examination in patients with thyroid nodules.

Materials and Methods: This prospective observational study included 120 consecutive patients who underwent thyroidectomy after preoperative ultrasonography using ACR-TIRADS at a tertiary care centre in South India. Ultrasound features including composition, echogenicity, margins, shape, and echogenic foci were used to categorize nodules from TR1 to TR5. FNAC was selectively performed, and histopathology served as the gold standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated. Statistical significance was determined using Chi-square test (p < 0.05).

Results: Of 120 nodules, 98 (81.7%) were benign and 22 (18.3%) malignant. Malignancy rates increased progressively with higher TIRADS categories. TIRADS demonstrated high sensitivity and NPV but lower specificity, reflecting overlap of suspicious sonographic features between benign and malignant lesions. The correlation between TIRADS score and histopathological outcome was statistically significant (p = 0.001).

Conclusion: Although ACR-TIRADS provides effective risk stratification of thyroid nodules, definitive diagnosis cannot be established by ultrasonography alone. FNAC serves as an essential intermediate diagnostic modality, while histopathological examination remains the gold standard. The combined use of TIRADS, FNAC, and histopathology provides the highest diagnostic accuracy and should be adopted for comprehensive evaluation of thyroid nodules.