Diagnostic value of strain ratio measurement in differential diagnosis of thyroid nodules coexisted with Hashimoto thyroiditis.

OBJECTIVE To evaluate the differential diagnostic potential of lesion stiffness assessed by the sonoelastographic strain index ratio (SR) for thyroid nodules coexist with Hashimoto thyroiditis (HT). METHODS A total of 50 focal thyroid nodules from 36 patients with HT (mean age 38.4 years; range 19-77) scheduled for fine-needle aspiration or thyroid surgery were included. After a routine conventional ultrasound evaluation, real-time ultrasound elastography examinations were performed. Strain and area ratios of each lesion were calculated within the same machine. Histological diagnosis was used as the reference standard. The elastography images were scored according to the Asteria elasticity score. The area under the curve (AUC) and cut-off point were obtained by receiver operating curve (ROC). Sensitivity, specificity and accuracy were compared. RESULTS A total of 38 nodules were benign and 12 were malignant on pathology. The mean strain ratios of benign and malignant lesions were 2.89 and 7.83 respectively. When a cut-off point of 5.03 was used, SR had a sensitivity of 75.0%, a specificity of 92.1% and an accuracy of 84.0%. The AUC values were 0.836. The diagnostic accuracy of the SR was superior to that of elastographic score. CONCLUSION Real-time elastography is a promising tool for differential diagnosis of thyroid nodules coexist with HT, and SR measurement could be an effective predictor. The best cut-off point for benign and malignant nodules in patients with HT was 5.03.