The lymph node (LN) metastases of papillary thyroid cancer have been observed in 14-64% of cases. Although central cervical LN metastasis initially occurs, the accuracy of preoperative diagnosis is lower than that of lateral cervical LN metastasis. To help determine the surgical strategy, the factors influencing the false negativity of preoperative imaging studies for central cervical LN metastasis were examined in this study.

Between July 2021 and June 2022, 611 patients with papillary thyroid cancer who underwent thyroid surgery and those with histological diagnoses of N0/1a were included. Enrolled patients underwent preoperative computed tomography (CT) and ultrasonography (US) preoperatively. Binary logistic regression analysis was used to identify false negatives.

The male-to-female ratio was 1:2.7, and 184 (30.1%) patients underwent total thyroidectomy. Two hundred thirty-five patients (38.5%) had central LN metastasis on postoperative pathology, while 151 patients (64.2%) had false negativity. The sensitivity, specificity, and accuracy of CT and US were 35.7%, 91.2%, and 69.8%, respectively. False-negative values increased as obesity or neck depth increased. The smaller the size of the tumor, the greater the false negativity. Additionally, the false-negative rate increased when there was no ETE or multifocality on ultrasonography.

Although the tumor size and ETE were small, false negativity in the preoperative imaging test for central cervical LN metastasis was related to the depth of the neck. Therefore, in patients with a thick neck who do not have factors associated with pN1a, early treatment or additional examinations may be required, considering the high false-negative rate of preoperative imaging tests.