Indocyanine green enhanced diode laser ablation for porcine gastric wall with ablation depth monitoring using scattering light

We developed laser ablation depth monitoring using scattering light on indocyanine green (ICG) enhanced diode laser ablation for gastric wall. We have developed selective diode laser ablation for ICG stained submucosa to treat submucosal gastric cancer. To prevent gastric perforation, real-time ablation depth monitoring should be applied to this treatment even though the ablation depth can be roughly judged through gastric endoscope by ablation surface color change. The backscattered light spectrum of the diode laser from the ablation area may be influenced by surface absorption and plume absorption. We observed the scattering light spectrum and found a small spectral dip at the ICG absorption wavelength. We demonstrated that this dip depth corresponded to the remained ICG stained submucosal layer thickness. We concluded that simple spectral monitoring may be effective to prevent gastric perforation during ICG enhanced diode laser ablation therapy.