Ultrasonoraphic Staging of Papillary Thyroid Carcinoma

Abstract

OBJECTIVE The purpose of this prospective study was to evaluate the overall accuracy of the ultrasonographic (US) staging of papillary thyroid carcinoma (PTC). MATERIALS AND METHODS A total of 94 consecutive patients with PTC underwent preoperative US. Two experienced radiologists prospectively evaluated primary tumors (diameter, number, extrathyroidal invasion etc.) and cervical lymph nodes for metastasis. A 5-point scale capsular abutment grade was used to represent the possibility of extrathyroidal invasion. Lymph nodes (LN) were divided into central and lateral groups according to N staging requirements. US criteria for lymph node metastasis were an absent hilum, hyperechoic change, a round shape, calcification, cystic change, or an abnormal color Doppler pattern. US results were correlated with histopathologic findings. RESULTS 127 cancers in the 94 patients were proven after surgery. US accurately identified 75.8% multifocal cancers (22/29) and 83.3% of patients with bilateral cancers (15/18). Using a cut-off value of 50% or more capsular abutment (grade 2), the sensitivity, specificity and accuracy of US prediction of extrathyroidal invasion were 85.3%, 70.0%, and 74.5%, respectively, and its overall T staging accuracy was 67.0% (63/94). A total of 147 cervical LN levels were dissected. All six US findings were significantly more frequent in metastatic LNs in the lateral group. However, in the central group, only two criteria (calcification, abnormal Doppler pattern) were found to significantly predict the presence of metastasis. The overall accuracy of US for N staging was 71.3% (67/94). CONCLUSION US is a feasible tool for the preoperative staging of PTC.