A total of 118 patients with 153 thyroid nodules underwent examinations with real-time ultrasonic elastography to obtain the strain ratio from longitudinal section and cross section. Receiver operating characteristic (ROC) curves were used to evaluate the value of elastography. The nodules are divided into two groups, group one included nodules which were near the isthmus and group two included other nodules. Diagnostic results were compared with pathological results.

The area under the ROC curve (AUC) of the strain ratios for differentiating benign and malignant thyroid nodules were 0.906 and 0.844. There was no statistical difference (Z=1.542, P>0.05). The best diagnostic cut-off points of the strain ratios were 3.65 and 3.58. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value of the strain ratio from longitudinal section for differentiating benign and malignant thyroid nodules were 81.2%, 80.8%, 81.0%, 87.2% and 71.2% and those of strain ratio from cross section were 77.2%, 76.9%, 77.1%, 84.4% and 63.4%. In group one, the AUC were 0.903 and 0.830. There was no statistical difference (Z=1.125, P>0.05). The best diagnostic cut-off points were 3.30 and 3.28. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value of the strain ratio from longitudinal section for differentiating benign and malignant thyroid nodules were 86.2%, 68.8%, 80.0%, 83.3% and 73.3% and those of strain ratio from cross section were 78.6%, 58.8%, 71.1%, 75.9% and 62.5%. In group two, the AUC were 0.906 and 0.852. There was no statistical difference (Z=0.936, P>0.05). The best diagnostic cut-off points were 3.33 and 3.71. The sensitivity, specificity, accuracy, positive predictive value, negative predictive value of the strain ratio from longitudinal section for differentiating benign and malignant thyroid nodules were 90.1%, 75.7%, 85.2%, 87.7% and 80.0% and those of strain ratio from cross section were 84.7%, 70.3%, 80.6%, 83.6% and 72.2%.

Real-time ultrasonic elastography is helpful to the differential diagnosis of thyroid nodules, but there is no statistical difference between the strain ratio from longitudinal section and cross section.