Elastosonographic strain index in thyroid nodules with atypia of undetermined significance

In this study, we aimed to evaluate the diagnostic accuracy of elastosonography (ESG) scoring and strain ratio in patients who had atypia of undetermined significance (AUS) cytology and underwent surgery for thyroid nodules.

250 patients were included in this study. They had at least one nodule in thyroid USG, underwent USG-guided FNAC according to the current guidelines and had AUS cytology according to the Bethesda system. Both elastosonographic color scoring and strain index were evaluated.

A total of 270 nodules in 250 patients were evaluated. Histopathologically, 81 (30 %) nodules were malignant and 189 (70 %) were benign. According to the ESG, 10 (3.7 %) nodules were assigned a score of 1, while 13 (4.8 %) nodules were assigned a score of 5. All of the nodules with an ESG score of 1 were histopathologically benign and 92.3 % of the patients with ESG score 5 were in the malignant group. Median SI in the benign histopathologic group was significantly lower compared to malignant group [(2.58 (IQR = 2.35) vs. 14.54 (IQR = 10.71)]. The optimal SI cut-off value to distinguish between the benign and malignant nodules was 6.66, with a sensitivity of 98.77 % and specificity of 96.30 %.

Our study is one of the first studies evaluating the role of SI for discriminating malignant and benign nodules with AUS cytology. Malignant nodules had a significantly higher stiffness compared to benign ones and SI had high sensitivity, specificity, positive predictive value, negative predictive value and accuracy for these nodules. We think SI may be helpful for the presurgical selection of nodules with AUS cytology.