Intraoperative tumor localization and tissue distinction during robotic adrenalectomy using indocyanine green fluorescence imaging: a feasibility study

To investigate the feasibility of a method for intraoperative tumor localization and tissue distinction during robotic adrenalectomy (RA) via indocyanine green (ICG) imaging under near-infrared light.

Ten patients underwent RA. After exposure of the retroperitoneal space, but before adrenal dissection was started, ICG was given intravenously (IV). Fluorescence Firefly™ imaging was performed at 1-, 5-, 10-, and 20-min time points. The precision with which the borders of the adrenal tissue were distinguished with ICG imaging was compared to that with the conventional robotic view. The number and the total volume of injections for each patient were recorded.

There were six male and four female patients. Diagnosis was primary hyperaldosteronism in four patients and myelolipoma, adrenocortical neoplasm, adrenocortical hyperplasia, Cushing’s syndrome, pheochromocytoma, and metastasis in one patient each. Procedures were done through a robotic lateral transabdominal approach in nine and through a robotic posterior retroperitoneal approach in one patient. Dose per injection ranged between 2.5 and 6.3 mg and total dose per patient 7.5–18.8 mg. The adrenal gland took up the dye in 1 min, with contrast between adrenal mass and surrounding retroperitoneal fat becoming most distinguished at 5 min. Fluorescence of adrenal tissue lasted up to 20 min after injection. Overall, ICG imaging was felt to help with the conduct of operation in 8 out of 10 procedures. There were no conversions to open or morbidity. There were no immediate or delayed adverse effects attributable to IV ICG administration.

In this pilot study, we demonstrated the feasibility and safety of ICG imaging in a small group of patients undergoing RA. We described a method that enabled an effective fluorescence imaging to localize the adrenal glands and guide dissection. Future research is necessary to study how this imaging affects perioperative outcomes.