Application Of Virtual Touch Tissue Quantification Techniques In The Differential Diagnosis Between Benign And Malignant Thyroid Nodules

Objective To investigate the clinical value of virtual touch tissue quantification(VTQ) technique of acoustic radiation force impulse imaging (ARFI) in differentiating malignant thyroid nodules from benign ones, and further to explore the impact factors of VTQ elastography in the evaluation of thyroid nodules.Methods180thyroid nodules in165patients were analyzed by2D ultrasound, color Doppler flow imaging(CDFI) and VTQ elastography. VTQ was used to determine the stiffness of the nodules and adjacent tissues of thyroid by measuring the value of shear wave velocities (SWV) at cross and longitudinal sections scanning, and then calculated difference between the nodules and the surrounding thyroid tissues. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic performance of VTQ and to find the best cut-off point. Z test was used to compare the diagnostic performance of these three methods in diagnosis of thyroid nodules. The multiple linear regression was used to analyze the relationship between the SWV of nodules and nodules maximum size, internal calcification, intranodular blood flow, nodules depth to the skin, probe scanning direction as well as pathologic finding.Results①180nodules included65benign nodules(54nodular goiters and11adenomas) and115malignant nodules(114papillary carcinomas and1follicular carcinoma). At cross and longitudinal sections, the mean SWV in benign nodules and the adjacent thyroid tissues were (2.15±0.78)m/s,(1.93±0.47)m/s and (2.22±0.71) m/s,(2.06±0.41)m/s, respectively, while in malignant thyroid nodules and the adjacent thyroid tissues were (2.97±1.12)m/s,(1.90±0.48)m/s and (3.09±1.08)m/s,(1.97±0.44)m/s, respectively.②A significant difference in mean SWV was found between malignant thyroid nodules on one hand and benign thyroid nodules(P<0.0001) or the adjacent thyroid tissues (P<0.0001) on the other hand, while no significant difference was found between benign thyroid nodules and the adjacent thyroid tissues(P>0.05).③The area under ROC curve (AUC) of cross and longitudinal sections scanning were0.772and0.799, using2.47m/s was the cut-off point, the corresponding sensitivity and specificity of VTQ were64.3%,71.9%and74.8%,73.4%, respectively. The AUC for the SWV of difference between thyroid nodules and surrounding tissues was0.831at longitudinal sections scanning, using0.34was the optimum value, the sensitivity and specificity were 87.0%and67.2%, respectively.④We found no statistically difference in SWV when using these three methods to differentiate diagnosis of thyroid nodules(P>0.05).⑤Multiple linear regression showed that there was no correlation of the SWV of nodules with respect to microcalcification, nodules depth or probe scanning direction (P>0.10), while pathologic finding, nodules maximum size and intranodular blood flow were significantly associated with the SWV (P<0.05). A regressive equation was established as:Y=1.163-0.054X1-0.054X3-0.228X6, and pathologic findings was the the most important factor influencing the SWV of nodules (standardized coefficient was-0.312).Conclusion①VTQ provides quantitative information about the thyroid tissue stiffiness, which is highly valuable in the differentiation diagnosis of benign and malignant thyroid nodules.②Pathologic finding, intranodular blood flow and nodules maximum size were the factors influencing the SWV of thyroid nodules, while nodules depth, probe scanning direction and microcalcification have nothing to do with the SWV of thyroid nodules.