Comparison of strain ratio with elastography score system in differentiating malignant from benign thyroid nodules

To prospectively compare strain ratio to elastography score system in distinguishing between malignant and benign thyroid nodules.

The local institutional review board approved the study, and all patients provided written informed consent. We examined 168 thyroid nodules (52 malignant and 116 benign) with freehand elastography. The elastogram was performed with both the five-degree elastography score system and thyroid tissue-to-nodule strain ratio before core biopsies as standard reference. The area under the curve (AUC) and the best cut-off point were both obtained using receiver-operating characteristic (ROC) curve analysis. The sensitivity, specificity, and accuracy of both techniques were compared with the χ(2) test. Furthermore, strain ratio distribution was also compared with histopathological result. P<.05 was considered to indicate significance.

The strain ratio distribution of malignant thyroid nodules significantly differed from that of benign nodules (all P<.001). The AUC of strain ratio was higher than that of the elastography score system (0.907 vs. 0.829; P<.05). By applying the best cut-off point of 3.855 for strain ratio and 3.5 for the elastography score system, strain ratio had significantly higher specificity (P<.05) in detecting malignant thyroid nodules. However, there was no significant difference in the sensitivity in distinguishing malignant thyroid nodules from benign ones between strain ratio and the elastography score system (P>.05).

Strain ratio is more specific than conventional elastography score system in differentiating malignant from benign thyroid nodules.