To determine the diagnostic efficacy of the computer aided diagnosis (CAD) system in discriminating malignant and benign thyroid nodules and the possible influencing factors.

This retrospective study analyzed 1035 patients with 1065 thyroid nodules at Sun Yat-sen University Cancer Center between May 2013 and October 2017. All the nodules was proven by ultrasound guided fine needle aspiration cytology or thyroidectomy. The CAD system was used to analyze the thyroid nodules, according to the categories defined by the K-TI-RADS, ATA, and ACR-TI-RADS guidelines. Using pathology as the gold standard, receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic efficacy of the CAD system. In addition, the differences of CAD diagnostic efficacy were compared among different thyroid nodule sizes and thyroid background.

The area under the ROC curve (AUC) of the ACR-TI-RADS was higher than those of the K-TI-RADS (Z=3.026, P=0.0025) and ATA (Z=3.669, P<0.001). The sensitivity of the ACR-TI-RADS was better than that of the K-TI-RADS (P<0.001), and was comparable to that of the ATA (P=0.7123). Using 4C as the cutoff value, the K-TI-RADS demonstrated a significantly higher specificity than the ATA and ACR-TI-RADS (P<0.001). The size of thyroid nodules influenced the diagnostic efficacy of CAD. The AUCs of CAD in the 5~<10 mm and ≥20 mm group were higher than those in the 10~<15 mm and 15~<20 mm group (P<0.001). There was no significant difference in AUC of the CAD between the normal background and Hashimoto thyroiditis background groups (P=0.82).

The CAD system exhibits a better diagnostic efficacy based on the ACR-TI-RADS, and the size of thyroid nodules influences the diagnostic efficacy of CAD

Thyroid nodule; Ultrasonography; Computer aided diagnosis