To assess the value of the thyroid imaging reporting and data system (TI-RADS), which was developed by the American College of Radiology in 2017, in diagnosing benign and malignant thyroid nodules.

A total of 176 patients with 216 thyroid nodules were retrospectively collected in this study at General Hospital of Eastern Theater Command. They were quantitatively evaluated for ultrasound features (structure, echo, morphology, margins, and focal echogenicity) by using the 2017 TI-RADS ultrasonographic stratification and were divided into a fine needle aspiration (FNA), a follow-up group, and an undealt group according to nodule size. The results were compared with FNA or surgery-based pathological results. The results of TI-RADS stratification between benign and malignant thyroid nodules were compared by the chi-square test. The receiver operating characteristic (ROC) curve analysis was conducted to determine the diagnostic values of thyroid TI-RADS stratification.

There were 84 benign and 132 malignant nodules in 216 thyroid nodules. They were classified into five categories according to the scores 0-14. The malignant rates of TI-RADS 1, 2, 3, 4, and 5 were 0, 0, 17.3%(4/23), 48.3%(29/60), and 93.4%(99/106), respectively. When TI-RADS 1, 2, and 3 thyroid nodules were classified as benign nodules, and TI-RADS 4 and 5 categories were classified as malignant nodules, the sensitivity, specificity, positive predictive value, and negative predictive value were 97.0%, 54.2%, 77.2%, and 91.8%, respectively. The area under the ROC curve was 0.918 (95% confidence interval [CI]: 0.881-0.956), and the Youden index was 0.699 with a critical value of 5.5. There was a statistically significant difference between TI-RADS stratification and pathological examination (χ²=77.222, Ρ<0.001). TI-RADS 1 and 2 nodules belonged to the undealt group. The rates of malignancy in TI-RADS 3 nodules were 18.2%(2/11), 0, and 25.0%(2/8) in the FNA group, follow-up group, and undealt group, respectively; the corresponding rates in TI-RADS 4 and 5 nodules were 31.0%(9/29), 63.6%(7/11), and 65.0%(13/20), and 96.3%(52/54), 88.9%(40/45), and 100.0%(7/7), respectively.

The TI-RADS classification of thyroid nodules has a high accuracy to identify benign and malignant nodules, especially benign nodules. Since TI-RADS 3 and above nodules of different sizes are all likely to be malignant, the indications for FNA of suspected malignant thyroid nodules according to TI-RADS classification in terms of nodule size may not be strictly obeyed.