Association between Tsukuba elasticity scores 4 and 5 on elastography and Bethesda undetermined cytology on US-guided FNA with 27-G needle, verified by histopathology: a cut-off point of 20 mm of diameter designated for thyroid nodules.

PURPOSE

The purpose of this study was to assess the performance of strain elastography (SE) in predicting malignancy for the thyroid nodules with undetermined cytology, Bethesda categories III and IV. The cut-off point was 20 mm of a thyroid nodule.

METHODS

A retrospective analysis from April 2012 to April 2016 was conducted by examining the records of 547 consecutive eligible patients with 655 thyroid nodules, the undetermined cytology of which surgery had been recommended.

RESULTS

A sum of 655 nodules in 547 patients were studied. Eighty-two (12.5%) of 655 thyroid nodules were Bethesda Category III and IV (undetermined cytology). Of the 655 thyroid nodules examined, 401 (61.2%) were less than 20 mm and 254 (38.8%) were more than 20 mm in diameter. No significant difference was detected between nodule sizes more than 20 mm in diameter and Tsukuba Elasticity score (TES) 4 and 5 by McNemar test and 0.677 area under the curve (AUC). No significant difference was detected between nodule sizes over 20 mm in diameter and Bethesda III and IV (undetermined cytology) by McNemar test and 0.632 AUC. In addition, no significant difference was detected between nodule size with the cut-off value of 20 mm and the histopathology of the thyroidectomies by McNemar test and 0.607 AUC.

CONCLUSION

Nodules size 20 mm in diameter was not a useful cut-off point for distinguishing malignant from benign thyroid nodules among the nodules with TES 4 and 5, Bethesda III and IV, and malignant histopathology.