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.