Quantitative Assessment Of Real-time Shear Wave Elastography Imaging Differentiating Benign And Malignant Thyroid Nodules

Objective:Application of shear wave elastography (SWE) technology, to measure the Emax values, and the Eratio of nodules and the surrounding normal gland, to determine the ROC curve, and to measure the Emax and Eratio value in the diagnosis of benign and malignant thyroid nodules.Methods:1. A retrospective analysis of the clinical data of 79 patients with thyroid nodules was finished, confirmed by pathology(23 benign,56 malignant), all of the nodules are located in unilateral. According to the maximal diameter of thyroid nodules, the patients was divided into group A(≤1 cm)and group B(>1 cm).2. All patients underwent conventional ultrasound (US) examination before surgery to observe the nodules of the location, shape, edge, size, internal echo and blood flow. The nodules were classified according to TI-RADS. All the nodules were examined by real-time shear wave elastography, adjust the Q-BOXTM for 3 mm and placed in the nodules within the most hard, and the Emax and Eratio of the nodules and the surrounding glands were detected.3. According to pathologic results, ROC curve (receiver operating characteristic curve) was drawn to calculate the area under the curve (AUC) and evaluate the best cut-off value of Emax and Eratio in differentiating benign and malignant nodules.4. According to the value of optimal operating point of SWE for differential diagnosis of thyroid nodules, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of diagnosis for thyroid nodules were analyzed respectively.5.The chi-square test were performed comparing the nodule size to see whether it was influential in diagnosis of benign and malignant thyroid nodules by the Emax and Eratio of SWE.Results:1. The pathology tests showed 23 benign cases,56 malignant cases. The benign nodules Emax was 33.957±8.221 kPa, and the malignant lesions Emax was 86.736± 48.715 kPa. There was statistically significant difference (P<0.05) between within the benign and malignant nodules. The benign nodules Eratio was 0.974±0.228, and the malignant lesions Eratio was 2.425±1.923.There was statistically significant difference (P<0.05) between within the benign and malignant nodules.2. Using the SWE quantitative analysis for these thyroid nodules, with the Emax boundary value of 42.35 kPa, the area under the ROC curve was 0.970 (95%CI: 0.940～1.000), the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of SWE were 92.9%,91.3%,92.4%,96.3%,84.0%. In group A(≤1 cm), the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of SWE were 93.9%、89.5%、92.3%、93.9%、89.5%. In group B(>1 cm), the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of SWE were 91.3%、100%、92.6%、100%、66.7%.3. According to ROC curve, the critical point of strain ratio between benign and malignant lesions was 1.25, the area under the ROC curve was 0.966 (95%CI:0.932-1.000), the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of SWE were 87.5%、91.3%、88.6%、96.1%、75.0%. In group A(≤1 cm), the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of SWE were 87.9%、89.5%、88.5%、93.5%、81.0%. In group B(>1 cm), the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of SWE were 87.0%、100%、88.9%、100%、57.1%.4. The nodule size has no influence in the diagnosis of benign and malignant thyroid nodule by the Emax and Eratio of SWE (P>0.05).Conclusion:1. The maximum Young’s modulus value and the strain ratio all contribute to identification of benign and malignant thyroid nodules, the difference was statistically significant in benign and malignant nodules.2. Taking 42.35 kPa as the threshold of Emax value or when the critical point of strain ratio was 1.25, SWE is more helpful in differentiating malignant and benign thyroid nodules.3. The nodule size has no influence in the diagnosis of benign and malignant thyroid nodules by the Emax and Eratio of SWE.