Preoperative ultrasonography of thyroid cancers: is it overdiagnosis or underdiagnosis?

Abstract

Objective To investigate the accuracy and missed diagnosis rate of preoperative ultrasound in the diagnosis of thyroid carcinoma. Methods With the method of natural language recognition, 816 solitary thyroid nodules which received thyroidectomy were enrolled for the analysis of preoperative ultrasound examination and post-operative pathology results. The accuracy and the rate of missed diagnosis of ultrasonography for the diagnosis of thyroid carcinoma and lymph node metastasis were evaluated with the pathological results as the gold standard. Results There were 783 (96.0%) malignant thyroid tumors, 6 (0.7%) follicular tumor with uncertain malignant potential, and 27 (3.3%) benign thyroid tumors. Ultrasonography yielded an accuracy of 96.1% in the differential diagnosis between benign and malignant thyroid nodules and an accuracy of 94.5% in the quantification of nodule numbers. 5.5% of solitary nodules reported by ultrasound were proved to be 2 or more malignant nodules after the surgery. Regarding the diagnosis of central lymph node, the preoperative ultrasound yielded an accuracy of 73.0% and a misdiagnosis rate of 38.7%. For the lateral neck lymph node, the accuracy was 88.3%, and the misdiagnosis rate was 3.4%. Conclusions Natural language recognition method can assist clinical research. Ultrasonography is valuable in the diagnosis of thyroid carcinomas and neck lymph nodes. However, ultrasonography has a certain rate of misdiagnosis for the quantification of nodule numbers, and for the diagnosis of lymph nodes in central and lateral necks. Key words: Ultrasonography; Thyroid carcinoma; Overdiagnosis; Underdiagnosis