Value of dual-phase, contrast-enhanced CT combined with ultrasound for the diagnosis of metastasis to central lymph nodes in patients with papillary thyroid cancer

Aims: To evaluate the diagnostic performance of computed tomography combined with ultrasound (CT/US) in metastatic central lymph nodes (CLNs) compared with US in patients with papillary thyroid cancer (PTC). Material and methods: Six-hundred patients with surgically proven PTC who underwent both US and CT examination before CLN dissection were evaluated retrospectively. All cases were divided into four subgroups according to the tumor size and number. Diagnostic performances of US, CT and CT/US were evaluated. Results: Among 600 patients with CLN dissection, CT/US showed higher sensitivity (89.10%) and accuracy (83.00%) than US alone (76.06%, 76.50%). In the subgroup of solitary non-microcarcinomas, the AUC of CT/US was significantly higher than that for US alone (0.827 vs. 0.722, P < 0.05). For the subgroup of solitary or multiple microcarcinomas, the performance efficiency of CT had no obvious advantage over that of US (0.698 vs. 0.740, 0.798 vs. 0.802, P > 0.05). For the subgroup of multiple non-microcarcinomas, CT, US and US/CT had high diagnostic efficacy (AUC > 0.8, Accuracy >80%. P > 0.05), and there was no significant difference between them. Conclusions: In the subgroup of solitary non-microcarcinoma, CT combined with US provided better diagnostic efficacy, and for those cases, complementary CT examination was recommended. In other subgroups, the diagnostic efficacy of US/CT was similar to that of US alone, and there was no significant benefit from additional CT examination.