To investigate the diagnostic value of CT signs of ipsilateral central lymph node metastasis (ICLNM) in single papillary thyroid carcinoma (PTC) by multivariate regression analysis.

The CT data of 302 single PTC with diameter >1.0 cm confirmed by operation and pathology were retrospectively analyzed. The optimal thresholds of lymph node metastasis diameter were obtained by receiver operating characteristic (ROC) curve analysis. And multivariate regression analysis was used to analyze the relation between lymph node size, degree of enhancement, calcification or cystic degeneration, central turbidity, positive lateral cervical lymph nodes and the ICLNM positivity.

In 302 PTC, the proportion of ICLNM positive and negative was 63.6% (192/302) and 36.4% (110/302) , respectively. According to the ROC curve, with the increase of lymph node diameter, the sensitivity of diagnosing lymph node metastasis decreased and the specificity increased. When the threshold was 0.4 cm, Youden index was the largest (0.358) , and the sensitivity and specificity was 50.5% and 80.3%, respectively. Multivariate analysis showed that the diameter≥0.4 cm, high enhancement, central turbidity and lateral cervical lymph nodes positivity were the independent risk factors of ICLNM, and the OR values were 4.189[95% CI (2.037-8.617) ], 3.875 [ (95% CI (1.561-9.617) ], 4.054[ (95%CI (2.230-7.371) ] and 8.735 [ (95% CI (1.093-69.831) ], respectively. Calcification or cystic degeneration was not statistically significant in ICLNM.

The diameter ≥0.4 cm, high enhancement, central turbidity and lateral cervical lymph nodes positivity are the independent risk factors of ICLNM. Although calcification or cystic degeneration is not the independent risk factor, it has high accuracy for ICLNM positivity. The accurate identification of these signs can help surgeons to take a more thorough surgical treatment and has great significance to reduce postoperative recurrence.

Thyroid cancer; Thyroid nodule; Central lymph node; Tomography; X-ray computed