Malignancy Risk Stratification of Thyroid Nodules: Comparison between the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) and the American Thyroid Association (ATA) Management Guidelines

Abstract

Background: Ultrasonography is the best choice to initially evaluate and stratify the malignancy risk of thyroid nodules. This study gives information and suggestion for further management for physicians. The two standard reporting systems are the ACR TI-RADS and ATA Management Guidelines. Objective: To compare the reliability of two ultrasonographic malignancy risk stratified systems and evaluate ultrasonographic features of benign and malignant thyroid nodules. Method: This diagnostic accuracy study were performed in Lampang Hospital. There were 83 patients who had thyroid neck masses. They were referred for evaluation and stratified for malignancy risk by using ultrasonogram. Both ACR TI-RADS and ATA Management Guidelines were applied and compared. These nodules were examined by cytology or pathology using FNA or thyroidectomy. The baseline characteristics, hormonal status and ultrasonographic features were recorded and reviewed. Results: 83 nodules were evaluated: malignant nodules = 20, benign nodules = 63. There was predominant in female patients. The range of age was 18-82 years old. The chi-square test of homogeneity of the two groups was in perfect agreement at 60.2%. The AuROC of ACR TI-RADS = 84.7%, log likelihood of ACR TI-RADS = -28.18 and the AuROC of ATA = 82.3%, log likelihood of ATA = -33.15. Both were great for detection and to differentiate malignancy nodules in TI-RADS 5 (LHR of positive = 10.24, 95%CI: 2.68, 46.72, p-value < .001) and ATA-High suspicious (LHR of positive = 4.9, 95%CI: 1.66, 14.72, p-value < .001). Conclusion: The two malignant risk stratification systems are useful when applied to evaluate malignancy risk in the thyroid gland, especially in highly suspicious nodules (ACR TI-RADS 5 and ATA high suspicion). The ACR TI-RADS is more beneficial when applied to the small size thyroid nodule (< 1.5-cm.), due to early detection, follow up management for small size cancer.