Computed Tomography-Detected Central Lymph Node Metastasis in Ultrasonography Node-Negative Papillary Thyroid Carcinoma: Is It Really Significant?

Because of the limitations in ultrasonography (US), the advantages of computed tomography (CT) for detecting central lymph node (LN) metastasis have been suggested in papillary thyroid carcinoma (PTC). First, we compared the diagnostic accuracy of US and CT for detecting central LN metastasis in 6577 central neck levels from 3668 PTC patients. Second, to examine the clinical impact of CT-detected central LN metastasis (CT cN1a) in PTC patients with clinically node negative in US (US cN0), we selected two groups: group I comprised 1245 US cN0 PTC patients who did not have CT scans and did not undergo central neck dissection (CND), while group II comprised 348 US cN0 and CT cN1a PTC patients who underwent CND. After propensity score matching, 254 matched pairs were yielded. For detecting central LN metastasis, CT showed significantly higher sensitivity (38.9 vs. 27.5 %; p < 0.001) and accuracy (66.1 vs. 63.2 %; p < 0.001) than US. Furthermore, US + CT showed significantly higher sensitivity (47.8 vs. 27.5 %; p < 0.001) and accuracy (69.0 vs. 63.2 %; p < 0.001) than US. After matching, radioactive iodine ablation (81.5 vs. 85.8 %; p = 0.235) and locoregional recurrence (p = 0.663) were not significantly different between groups I and II. Despite the diagnostic advantages of preoperative CT, 'CT-based CND' in US cN0 PTC patients did not significantly influence postoperative management and locoregional recurrence. The strategy for the management of central neck in PTC patients can be sufficiently determined by US only.