目的    评价甲状腺术前高频超声对喉返神经喉外分支变异的预测价值。  方法    前瞻性收集2023年12月至2024年6月笔者单位进行甲状腺切除术患者的术前超声资料，留存甲状腺下动脉（ITA）水平和环甲关节（CTJ）水平的横断面图像，分别测量上述平面喉返神经的最大径（SD）和横截面积（CSA）；根据术中喉返神经探查结果，分为喉外未分支组和喉外分支组，对比两组参数差异，根据约登指数计算组间的临界值。  结果    共纳入来自76例患者的95条神经，术中发现20.0%（19条）神经存在喉外分支，喉外分支组CTJ水平的神经SD、CSA及与ITA水平相应参数的比值均显著低于未分支组（P<0.05）。预测喉返神经喉外分支的临界值为CTJ水平CSA 1.4 mm2（AUC=0.823）及该参数与ITA水平的比值0.78（AUC=0.875）。  结论    甲状腺术前高频超声能够预测喉返神经喉外分支，对甲状腺切除手术规划和术中喉返神经保护有积极意义。

Objective    To evaluate the predictive value of high frequency ultrasound on the extra-laryngeal branching of recurrent laryngeal nerve.   Methods    Preoperative ultrasound data of patients undergoing thyroidectomy from December 2023 to June 2024 were collected and cross-sectional ultrasound images of lower thyroid artery (ITA) and cricothyroid  joint (CTJ) were saved to measure the maximum diameter (SD) and cross-sectional area (CSA) of the recurrent laryngeal nerve area on the above planes. The results of exploration of recurrent laryngeal nerve during thyroidectomy were used as the gold standard, the cases were divided into extra-laryngeal branching group and non-extralaryngeal branching group. Statistical differences of parameters between the two groups were compared, and the cut-off between the groups was calculated according to the Youden index.    Results   A total of 95 nerves from 76 patients were included, 19 extra-laryngeal branching nerves (accounting for 20.0%) were confirmed intraoperatively. The SD, CSA on CTJ level and the ratio of the parameters to ITA level were significantly lower in the branching group than that of the non-extralaryngeal branching group (P<0.05). The cut-off value for predicting the extra-laryngeal branching was CSA of 1.4 mm2 of the nerve (AUC=0.823) and the ratio of this parameter to ITA level was 0.78 (AUC=0.875).  Conclusions  Preoperative high-resolution ultrasound could predict extra-laryngeal branching of recurrent laryngeal nerve, and have positive significance for surgical planning and nerve protection of thyroidectomy.