Safety and feasibility of near-infrared image-guided lymphatic mapping of regional lymph nodes in esophageal cancer

Objective: To assess safety and feasibility of an intraoperative, minimally invasive near-infrared (NIR) image-guided approach to lymphatic mapping in patients with esophageal cancer. Methods: Although local lymph nodes (LNs) are removed with the esophageal specimen, no techniques are available to identify the regional LNs (separate from the esophagus) during esophagectomy. We hypothesize that NIR imaging can identify regional LNs with the potential to improve staging and guide the extent of lymphadenectomy. Nine of the 10 patients enrolled had resectable esophageal adenocarcinoma and underwent NIR mapping following peritumoral submucosal injection of indocyanine green (ICG) alone or premixed in human serum albumin (ICG:HSA) before resection. NIR imaging was performed in situ and ex vivo. Results: In 6 of the 10 patients, intraoperative NIR imaging demonstrated an NIR signal at all tumors and in 2 to 6 NIR+ regional LNs. NIR+ LNs were not identified in 4 patients: 1 patient with occult stage IV disease, for whom further imaging was not performed and thus was excluded from analysis, and 3 patients in whom ICG was used without HSA. Identification of local LNs on the esophagus was obscured by a peritumoral background. Importantly, the pathological status of NIR+ regional LNs reflected overall regional nodal status. Conclusions: NIR lymphatic mapping is safe and feasible in patients with esophageal cancer and can identify regional LNs when ICG: HSA is used. Although more work is needed to improve background signals and local LN identification, intraoperative detection of regional NIR+ LNs allows an in-depth histological analysis of LN basins not commonly scrutinized as part of the specimen and may improve the detection of occult nodal disease.