Qualitative and quantitative superb vascular imaging in the diagnosis of thyroid nodules ≤10 mm based on the Chinese Thyroid Imaging Reporting and Data System 4 (C-TIRADS 4)

BACKGROUND: To compare qualitative and quantitative superb microvascular imaging (SMI) and determine the value of SMI in the diagnosis of thyroid nodules (TNs) ≤10 mm based on the Chinese Thyroid Imaging Reporting and Data System 4 (C-TIRADS 4). METHODS: From October 2020 to June 2022, 106 patients with 109 C-TIRADS 4 (C-TR4) TNs (81 malignant, 28 benign) at the Peking Union Medical College Hospital were included. Qualitative SMI reflected the vascular pattern of the TNs and quantitative SMI was recorded by the vascular index (VI) of the nodules. RESULTS: The VI was significantly higher in malignant nodules versus benign nodules both in the longitudinal (19.9±11.4 vs. 13.8±10.6, P=0.01) and transverse (20.2±12.1 vs. 11.3±8.7, P=0.001) sections. The area under the curve (AUC) of qualitative and quantitative SMI did not show a statistical difference in the longitudinal {0.657 [95% confidence interval (CI): 0.560–0.745] vs. 0.646 (95% CI: 0.549–0.735), P=0.79} and transverse [0.696 (95% CI: 0.600–0.780) vs. 0.725 (95% CI: 0.632–0.806), P=0.51] sections. Next, we combined qualitative and quantitative SMI to upgrade and downgrade the C-TIRADS classification. If a C-TR4B nodule had VIsum >12.2 or intra-nodular vascularity, the original C-TIRADS was upgraded to C-TR4C. If a C-TR4C or C-TR4B nodule manifested VIsum ≤12.2 and no intra-nodular vascularity, the original C-TIRADS was downgraded to C-TR4A. As a result, 18 C-TR4C nodules were downgraded to C-TR4A and 14 C-TR4B nodules were upgraded to C-TR4C. The new model of SMI + C-TIRADS showed high sensitivity (93.8%) and accuracy (79.8%). CONCLUSIONS: There is no statistical difference between qualitative and quantitative SMI in the diagnosis of C-TR4 TNs. The combination of qualitative and quantitative SMI may have the potential to manage diagnosis of C-TR4 nodules.