Correlation and agreement between superb micro-vascular imaging and contrast-enhanced ultrasound for assessing radiofrequency ablation treatment of thyroid nodules: a preliminary study.

BACKGROUND: To evaluate the correlation and agreement between superb micro-vascular imaging (SMI) mode and the contrast-enhanced ultrasound (CEUS) mode for the ablative completeness and the volumes of ablation lesions to determine the clinical application value of SMI in follow-up after radiofrequency ablation. METHODS: From April 2020 to June 2020, two radiologists used SMI and CEUS mode to measure the volume of the ablation lesion. We use intra-class correlation coefficient (ICC), scatter plots and Bland-Altman plots to evaluate the correlation and agreement of the two techniques. In addition, intra- and inter-observer reliability in volume measurement of ablation lesions with SMI mode was assessed. RESULTS: SMI mode and CEUS mode have good agreement in the evaluation of ablative completeness. The ICC was 0.876 and 0.928 of reader A and reader B between SMI mode and CEUS mode in terms of ablation lesions volume measurement. There was a strong correlation between the two modes in both reader A and reader B (rA = 0.808; rB = 0.882). The ICC was 0.836 for the inter-observer reliability of SMI technique. The scatter plot showed a good linear relation (r = 0.715). In the Bland-Altman plot, 4.35% (1/23) of the points was outside the 95% limits of agreement. The ICC was 0.965 for the intra-observer reliability of SMI technique, the scatter plot also showed a strong linear correlation (r = 0.965). In the Bland-Altman plot, 8.70% (2/23) of the points was outside the 95% limits of agreement. CONCLUSIONS: SMI and CEUS have good agreement and correlation in the ablation volume measurement. SMI technology is expected to be applied as an alternative to CEUS in the clinical follow-up of ablation lesions.

The role of multimodal ultrasonic flow imaging in Thyroid Imaging Reporting and Data System (TI-RADS) 4 nodules.

BACKGROUND: Color Doppler imaging (CDFI), contrast-enhanced ultrasound (CEUS), and superb micro-vascular imaging (SMI) are used to observe blood flow characteristics in Thyroid Imaging Reporting and Data System (TI-RADS) 4 nodules. The ability of these techniques to distinguish benign from malignant nodules was investigated. METHODS: A total of 75 TI-RADS 4 nodules were examined using CDFI, SMI, and CEUS. The blood flow characteristics shown by the three methods were added to the current TI-RADS classification to establish a new TI-RADS classification. The value of the three methods and the diagnostic accuracy of the new and old TI-RADS classification were compared. RESULTS: SMI better captured type II flow in benign nodules and type III flow in malignant nodules relative to CDFI. Malignant nodules detected with CEUS manifested mainly with hypo-enhancement, whereas benign nodules showed iso- and hyper-enhancement. The areas under the receiver operating characteristic (ROC) curves (AUC) obtained through the aforementioned flow distribution models were 0.690 (CDFI), 0.840 (SMI), 0.910 (CEUS), and 0.903 (CEUS and SMI combined mode), respectively. The diagnostic value of CEUS was the highest. Joint inspection using SMI with CEUS showed certain advantages in sensitivity, although the overall accuracy was equal to that of CEUS alone. Except for CDFI, the AUC of the new TI-RADS classification was significantly higher than that of the old one. Perforating vessels and low enhancement were independent predictors of thyroid carcinoma. CONCLUSIONS: Both SMI and CEUS visualized lower-velocity blood flow within TI-RADS 4 nodules. The new TI-RADS classification described here could improve diagnostic accuracy.