The clinical application of indocyanine green fluorescence imaging in the lymph node dissection of radical thyroidectomy

Objective To investigate the efficacy and safety of indocyanine green fluorescence imaging in the lymph node dissection of radical thyroidectomy. Methods Radical thyroidectomy was performed using indocyanine green fluorescence imaging technology for two patients at the Department of General Surgery of Chinese People’s Liberation Army (PLA) General Hospital in July 2018. Indocyanine green was injected into the thyroid glands after bilateral thyroid glands were exposed during operation. Bilateral total thyroidectomy plus central lymph node dissection was performed in case 1, and bilateral total thyroidectomy plus central area and left lateral area (area Ⅱ a, III, IV) lymph node dissection was performed in case 2. Both operations were performed under the guidance of real-time fluorescence imaging system. The total number of lymph nodes detected, the number of small lymph nodes (diameter less than 3 mm) , the level of parathyroid hormone (PTH) , the incidence of complications such as hypocalcemia, hoarseness and short-term recurrence were observed. Results After excitation by the near-infrared light of the fluorescence detector probe, the display showed that the parathyroid gland and surrounding tissues were not visualized, and the thyroid glands and lymph nodes were brightly illuminated. The number of lymph nodes dissected in the central region of the two patients was 20 (13 with diameter less than 3 mm) and 10 (6 with diameter less than 3 mm) , respectively. For case 2, 13 lymph nodes were dissected in the left lateral area (area Ⅱa, III, IV) , and 8 lymph nodes with diameter less than 3 mm were dissected. There were no complications such as hypocalcemia and hoarseness after operation. The levels of parathyroid hormone and serum calcium were normal on the first day and 3 months after operation. There was no recurrence or metastasis of the tumors by ultrasonography 3 months after operation. Conclusion Indocyanine green fluorescence real-time imaging technology can help to identify lymph nodes specifically during radical thyroidectomy, and can achieve real-time dynamic imaging, which can make lymph node dissection more thorough and can be used as a new method for lymph node tracing in thyroid cancer surgery. Key words: Indocyanine green; Fluorescence imaging; Thyroid carcinoma; Lymph node dissection