Application Of Strain Ratio In The Differential Diagnosis Between Benign And Malignant Thyroid Nodules

Objective To evaluate diagnostic value of strain ratio(SR) in differential diagnosis of benign and malignant thyroid nodules by using real-time tissue elastosonography(RTE), and further to explore the influencing factors of SR in differentiating thyroid nodules.Methods One hundred and seventy-one patients with a total of 171 thyroid nodules were analyzed retrospectively. Their images, including 2D ultrasound, color Doppler flow imaging(CDFI) and RTE were reviewed and conventional ultrasonic features(including the maximum diameter, echogenicity, composition, shape, magin, tall and wide ratio,depth, calcification and intranodular blood flow) and SR at longitudinal sections scanning were recorded. Receiver-operating characteristic curve(ROC) was employed to assess the diagnostic efficiency of SR in differentiating malignant nodules from benign ones. x2 test was used to compare the diagnostic performance of conventional ultrasound and SR in diagnosis of thyroid nodules. Firstly, the correlation between the aforementioned factors and SR was assessed by using malignant lesions as the research subjects. And then,the multiple linear regressions(MLR) was employed to evaluate the influence of particular features which turned out to be an important disturbing factor affecting SR value of the lesion in the first step of analysis and pathological type in all nodules(benign and malignant) on SR value.Results ① 171 patients with a total of 171 thyroid nodules, including 53 benign nodules(44 nodular goiters, 7 follicular adenomas and 2 focal subacute thyroiditis) and118 malignant nodules(116 papillary carcinomas, 1 medullary carcinoma and 1 follicular carcinoma). ②The sensitivity, specificity and accuracy of conventional ultrasound in the diagnosis o f thyroid nodules were 77.1%、75.5% 、76.6%. With a cut-off point of SR3.67,the sensitivity, specificity and accuracy of SR was 85.6% and 81.1%, respectively, and the area under ROC curve(AUC) was 0.891. There was significant difference in sensitivity and specificity between conventional ultrasound and SR.③The mean SR of the malignant nodules(6.33±3.03) was statistically higher than that of the benign nodules(2.64±1.96)(P<0.05).④Correlation between the maximum diameter and calcification and SR value was significant(P<0.05, r= 0.345 and 0.261 respectively). However, there was no significant correlation between other features(including composition, depth, shape,magin and intranodular blood flow) and SR value(P>0.05). ⑤ MLR indicated that the maximum diameter, calcification and the type of pathology of the nodule were associated with SR value(P<0.05). Among them, pathological nature was the most significant impact factor with a standardized coefficient 0.494).Conclusions ①SR value can be used to evaluate the hardness of thyroidnodules semi-quantitatively, but still need to combine with conventional ultrasound for diagnosis.② Its value mainly depends on the pathological nature of the nodules. The maximum diameter and calcification are also the influencing factors of SR value. However, the composition, shape, margin, depth, and intranodular blood flow have no obvious effect on SR value.