Comparison of the diagnostic performances of ultrasonography, CT and fine needle aspiration cytology for the prediction of lymph node metastasis in patients with lymph node dissection of papillary thyroid carcinoma: A retrospective cohort study.

Purpose: To evaluate the diagnostic performances of ultrasonographic (US) findings, computed tomography (CT) findings and fine needle aspiration cytology (FNAC) for the prediction of cervical lymph node (LN) metastases of papillary thyroid carcinoma (PTC) to determine which LN should be dissected.

Methods: 376 LNs in 302 patients who underwent both US-guided skin surface LN markings and CT before LN dissection were analyzed retrospectively. Indications for LN dissection were suspicious US findings of LN metastases (n = 300), suspicious CT findings (n = 67) or surgeon's request (n = 9). Diagnostic performances of US, CT and FNAC (including thyroglobulin (Tg)) were evaluated. The correlations of suspicious US, CT finding or malignant FNAC with the size, number and the presence of extranodal extension of metastatic LNs were analyzed.

Results: US indication of LN dissection was significantly correlated with malignancy (p < .0001). Values of area under the curve of highly suspicious US findings and FNAC+Tg were significantly higher than that of CT (0.786, 0.878, 0.585, p < .0001, respectively). Suspicious US, CT findings and malignant FNAC+Tg were significantly associated with the largest size of metastatic LNs (p = .003, p = .0003, and p = .0006, respectively) and total number of metastatic LNs (p = .007, p = .038, and p = .005, respectively).

Conclusion: The diagnostic performance of US or FNAC was superior to CT and highly suspicious US findings could be complimentary to FNAC results in predicting LN metastases of PTC. LN dissection should be performed for the LNs with any suspicious US findings or malignant FNAC results rather than LNs with only suspicious CT findings.