The use of sonoelastographic elasticity index to differentiate benign and malignant thyroid nodules

The aim of this study is to evaluate the elasticity index of thyroid nodules by sonoelastographic imaging, and to determine the cut-off value to distinguish malignant nodules from benign nodules with optimum sensitivity and specificity.

Fine needle aspiration biopsy (FNAB) of 84 cases were evaluated with B-mode US and Sonoelastography (USE) preoperatively. The elasticity score (ELX 2/1) index of the nodules were calculated. Seventy-three patients with diagnostic biopsy results were included in this study.

According to the FNAB results, 9 (12 %) nodules were malignant, 64 (88 %) nodules were benign. All malignant nodules were papillary carcinoma, and their diagnosis was confirmed with thyroidectomy. The ELX 2/1 index of all malignant nodules was higher than 1.65. The ELX 2/1 index of 45 (70.3 %) benign nodules was lower than 1.65 whereas the ELX 2/1 index of 19 (29.7 %) benign nodules was higher than 1.65. Using an ELX 2/1 index cut-off value of 1.65 led to a sensitivity of 100 % and a specificity of 71 % in detecting papillary thyroid carcinomas.

Assessing the ELX 2/1 index as a screening test and deciding on FNAB accordingly, in addition to gray-scale ultrasound findings of the nodules, will be beneficial in order to prevent unnecessary biopsies.