Preoperative ultrasound-guided carbon nanoparticles localization for metastatic lymph nodes in papillary thyroid carcinoma during reoperation: A retrospective cohort study

Due to the damaged anatomical structure and a large amount of fibrous and scar tissues in the surgical field, reoperation of papillary thyroid carcinoma is difficult. This study introduces a new method of locating metastatic lymph nodes during reoperation and evaluates the effectiveness and safety of the preoperative ultrasound-guided carbon nanoparticles (CNs) localization. This retrospective cohort study enrolled 52 patients who were diagnosed with lymph node metastasis by histopathology and underwent reoperation from October 2015 to February 2016. The modified radical neck dissection or selective neck node dissection was performed. A total of 26 patients underwent preoperative ultrasound-guided CNs injection, and other 26 patients did not. Tolerance, the result of injection, the number of resected metastatic lymph nodes, and postoperative complications were recorded and analyzed. In CNs group, 102 suspicious nonpalpable lesions in 26 patients were injected with CNs, and 99 of the 102 lesions were successfully identified by surgeon in the reoperation. The positive rate of resected lymph nodes in total, in the central compartment, and in the lateral compartment were 31.6%, 31.2%, and 32.8%, respectively, which was significantly higher than that in the control group (P < 0.001, P < 0.001, and P = 0.041). In addition, the positive rates of levels III, IV, and V in the CNs group were 35.6%, 21.9%, and 30.5%, respectively, which was significantly higher than that in the control group (P < 0.001, P = 0.005, and P = 0.01). In additional, in the CNs group, the rate of temporary hypoparathyroidism was significantly lower compared with the control group (0% vs 26.9%, P = 0.021). Preoperative ultrasound-guided CNs injection is a safe and effective method for localization of the metastatic lymph nodes during reoperation.