Objective:To investigate the diagnostic performance of different thyroid imaging reporting and data systems (TI-RADS) in the diagnosis of medullary thyroid carcinoma (MTC) .Methods:A total of 160 thyroid nodules diagnosed as MTC by postoperative pathology from Aug. 2011 to Aug. 2022 at the First Affiliated Hospital of Zhengzhou University were included. Additionally, 160 papillary thyroid carcinomas (PTC) and 160 benign nodules were randomly selected as controls during the same period. Differences in gender, age, nodule diameter and various ultrasound features were observed. The nodules were classified according to American College of Radiology (ACR) TI-RADS, artificial intelligence (AI) TI-RADS and Chinese (C TI-RADS). Then, receiver operating characteristic curve (ROC) were plotted to calculate the diagnostic value. The Kendall concordance coefficient was used to evaluate the interobserver consistency of each TI-RADS system.Results:There was no statistically significant difference in gender among the three groups ( χ2=1.17, P=0.558). However, significant differences were observed in age and nodule diameter ( F=12.08,40.12, P<0.001 for both). The area under ROC (AUC) for diagnosing MTC and benign nodules using ACR, AI, and C-TIRADS were 0.762, 0.773, and 0.761, respectively, with no statistically significant differences ( Z=1.33, 0.01, 0.87, P=0.183, 0.994, 0.386). However, the sensitivity of C TI-RADS (87.5%) was lower than that of ACR and AI TI-RADS (both 95.0%) ( P=0.018). After combining the biopsy threshold, the false negative rate of C-TIRADS was lower than that of ACR (30.6% vs. 41.3%) ( P=0.048) and AI TIRADS (30.6% vs. 43.1%) ( P=0.020). The inter-observer diagnostic consistency of C-TIRADS was superior to ACR (0.884 vs. 0.819, P<0.001) and AI TIRADS (0.884 vs. 0.839) ( P<0.001) . Conclusions:AI and ACR TI-RADS have higher sensitivity in diagnosing MTC, while C TI-RADS has a lower puncture missed diagnosis rate. AI has similar diagnostic performance to ACR TI-RADS and can replace ACR TI-RADS.