Diagnostic performances of the KWAK-TIRADS classification, elasticity score, and Bethesda System for Reporting Thyroid Cytopathology of TI-RADS category 4 thyroid nodules.

Objective: To explore the value of the KWAK Thyroid Imaging Reporting and Data System (KWAK-TIRADS), elasticity score (ES), and Bethesda System for Reporting Thyroid Cytopathology (BSRTC) in the diagnosis of suspicious thyroid nodules.

Methods: The study included 392 cases of TI-RADS category 4 thyroid nodules that underwent thyroidectomy between January 2017 and October 2019. All patients underwent ultrasonography, ultrasound elastography, and fine-needle aspiration cytology (FNAC) before surgery. The nodules were classified into different categories based on the KWAK-TIRADS, ES, and BSRTC. Patients were divided into two groups based on postoperative pathological characteristics. The sensitivity (Se), specificity (Sp), and area under the receiver operating characteristic (ROC) curve were calculated. Student's t-test and Pearson chi-square test were used to compare diagnostic performance.

Results: There were 159 patients in the benign group and 233 in the malignant group. The percentage of malignant nodules in KWAK-TIRADS categories 4a, 4b, and 4c were 44.3%, 64.8%, and 92.9%, respectively. The percentages of malignant nodules in ES 2, 3, 4, and 5 were 0%, 37.1%, 93.8%, and 100%, respectively. The percentage of malignant nodules in BSRTC levels I, II, III, IV, V and VI were 57.1%, 2.8%, 9.9%, 76.6%, 99.1%, and 100%, respectively. Among those methods, the BSRTC had better diagnostic efficiency than the KWAK-TIRADS and ES (Sp 81.1%, Se 93.6%, and AUC 0.918, P<0.01). Among the combined methods, KWAK-TIRADS+ES+BSRTC was more effective than KWAK-TIRADS+ES, KWAK-TIRADS+BSRTC, and ES+BSRTC (Sp 93.7%, Se 91.4%, and AUC 0.967, P<0.01).

Conclusions: The combination of KWAK-TIRADS, ES, and BSRTC can improve the accuracy of identifying category 4 thyroid nodules.