Preoperative diagnosis of cervical metastatic lymph nodes in papillary thyroid carcinoma: Comparison of ultrasound, computed tomography, and combined ultrasound with computed tomography

Abstract

Background: Although ultrasound ( US) is routinely used for the preoperative evaluation of neck nodes in patients with papillary thyroid carcinoma ( PTC), the diagnostic role of computed tomography ( CT) has not been established. The purpose of our study is to determine the diagnostic accuracies of US, CT, and combined US and CT ( US/CT) for detecting metastatic neck nodes in patients with PTC. Methods: 165 consecutive patients ( 140 females and 25 males, mean age 47.9 years) with surgically proven PTC underwent US and CT for preoperative evaluation. CT was performed 2 or 3 months before radioiodine therapy. We assessed the diagnostic accuracies of US, CT, and US/CT using level- by- level analysis. Results: In terms of predicting node metastases, overall sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of US were 51%, 92%, 77%, 81%, and 76%, respectively. Those of CT were 62%, 93%, 81%, 84%, and 80%, respectively, and those of US/CT were 66%, 88%, 79%, 77%, and 81%, respectively, at all neck levels. US/CT significantly increased sensitivity and demonstrated similar specificity compared with US alone in lateral neck levels ( p =0.02 and p =1.0, respectively). US/CT increased sensitivity ( p = 0.01), but decreased specificity compared with US alone in the central neck levels ( p 0.02). CT provided additional benefit for detecting metastatic nodes at more than one level in 8% of all patients, in 14% of patients with suspected nodal metastasis on US, and in 25% of patients with metastatic lymph nodes. Conclusions: The US/CT combination was found to be superior to US alone for the detection of metastatic lymph nodes in the lateral neck levels in PTC patients by level- by- level analysis.