Novel technique of virtual touch tissue imaging quantification shear wave elastography in differential diagnosis of thyroid nodules:initial experience / 中华医学超声杂志（电子版）

ABSTRACT

Objective To evaluate diagnostic value of the novel virtual touch tissue imaging quantification (VTIQ) technique of acoustic radiation force impulse (ARFI) shear wave elastography in the differential diagnosis between benign and malignant thyroid lesions. Methods From June to July 2014, the imaging data of 82 thyroid lesions in 75 patients proven by fine needle aspiration cytology (FNAC) biopsy on conventional ultrasound and VTIQ were retrospectively analyzed. The thyroid nodules were examined by conventional ultrasound firstly and then the lesions were classified by thyroid imaging report and data system (TI-RADS). The maximum, minimum, median and average of shear wave velocity (SWV) values were obtained from multiple SWV measurement under the VTIQ speed mode. The region of interest (ROI) was determined according to the VTIQ quality mode after the patients holding the breath. According to the FNAC cytology results, ROC curve were plotted to determine the most accurate SWV value and the cut-off value for differential diagnosis. Results According to the FNAC results, grading≥5 level was set as the positive results and FNAC<5 level as the negative results. There were 28 positive nodules and 54 negative nodules in 82 thyroid nodules. The positive rates of TI-RADS classification were consistent with the theoretical results. The SWVmax, SWVmin, SWVmedian, and SWVmean on VTIQ of negative and positive thyroid nodules were (3.2±0.6), (2.2±0.4), (2.7±0.4), (2.6±0.4) m/s, and (4.6±1.7), (3.1±0.8), (3.5±1.0), (3.6±1.1) m/s. There were significant differences between positive and negative thyroid nodules in SWVmax, SWVmin, SWVmedian, and SWVmean on VTIQ (t=3.53, 3.68, 3.32, 3.81, all P<0.01). Based on the area under curve of ROC, the SWVmean value in the nodule was the best value in comparison with other SWV values. The cut-off value of VTIQ mean was 2.9 m/s. According to ROC curve analysis, the sensitivity, specificity and Youden index for VTIQ were 70.6%, 88.5%, 0.59, respectively. Conclusion The study proved that VTIQ elastography technique plays an important role in differential diagnosis of thyroid nodules and the VTIQ SWVmean is the best parameter for differential diagnosis.