Intraoperative spectral imaging versus ICG fluorescence for gastric conduit viability in esophagectomy

Jens De Winne, Hanne Vanommeslaeghe, Danilo Babin, Hiep Luong, Siri Luthman, Elke Van Daele, Wim Ceelen

Anastomotic leakage remains a critical complication following esophagectomy, occurring in 8–20% of patients. While indocyanine green fluorescence imaging (ICG-FI) is commonly used to assess perfusion, it requires dye injection and does not directly measure tissue metabolism. This study evaluates a real-time, contrast-free spectral imaging (SI) system for quantifying gastric conduit oxygenation ( $$\mathrm {StO_{2}}$$ ) and compares its performance to ICG-FI. Intraoperative SI was successfully performed in 33 patients undergoing laparoscopic Ivor Lewis esophagectomy using a video-rate snapshot spectral camera, acquiring 16 spectral bands in the 460–600 nm range. A deep learning model estimated $$\mathrm {StO_{2}}$$ of the gastric conduit and quantitative perfusion metrics were derived from ICG-FI time-intensity curves. Local capillary lactate levels were measured as a physiological reference for tissue hypoxia. Statistical analyses compared $$\mathrm {StO_{2}}$$ and ICG-FI metrics. SI successfully differentiated well-perfused from ischemic tissue (median $$\mathrm {StO_{2}}$$ : $$69.16\%$$ vs. $$31.58\%$$ , p < 0.001). The estimated $$\mathrm {StO_{2}}$$ showed a strong negative correlation with local capillary lactate (r=-0.72, p < 0.001). While quantitative ICG-FI metrics ( $$\mathrm {T_{1/2}}$$ and $$\mathrm {AUC_{50\%}}$$ ) revealed significantly reduced perfusion at the anastomosis site compared to well-perfused tissue (p < 0.001), they showed only a moderate correlation with $$\mathrm {StO_{2}}$$ (r=0.50, p < 0.001). Notably, in a patient who developed anastomotic leakage, both modalities detected ischemia intraoperatively, but they show different transition borders, with SI indicating a more extensive hypoxic area than ICG-FI. Snapshot SI provides a real-time, objective assessment of tissue oxygenation without the need for contrast agents. Its strong correlation with lactate suggests it may offer potential complementary value to dye-based perfusion imaging, potentially improving anastomotic site selection, although outcome-based validation studies in larger cohorts are needed.