Fig. 3

a Completed left thoracic recurrent laryngeal nerve (RLN) node dissection. b Intraoperative ultrasound image showed one non-metastatic lymph node 0.50 cm in diameter located in the left RLN region. c Intraoperative ultrasound image showed the non-metastatic lymph node located in the left RLN region. d Intraoperative ultrasound image showed the metastatic lymph node located in the left RLN region. LN, lymph node; AO, aorta; PA, pulmonary artery; SCA, subclavicular artery