This study was to evaluate the feasibility of near infrared (NIR) fluorescent images as a tool for evaluating the perfusion of the gastric tube after esophagectomy. In addition, we investigated the time required to acquire enough signal to confirm the presence of ischemia in gastric tube after injection of indocyanine green (ICG) through peripheral versus and central venous route.
4 porcine underwent esophagogastrostomy and their right gastric arteries were ligated to mimic ischemic condition of gastric tube. ICG (0.6mg/kg) was intravenously injected and the fluorescence signal-to-background ratios (SBR) were measured by using the custom-built intraoperative color and fluorescence imaging system (ICFIS). We evaluated perfusion of gastric tubes by comparing their SBR with esophageal SBR.
In ischemic models, SBR of esophagus was higher than that of gastric tube (2.8±0.54 vs. 1.7±0.37, p<0.05). It showed high esophagus-stomach signal to signal ratio. (SSR, 1.8±0.76). We also could observe recovery of blood perfusion in few minutes after releasing the ligation of right gastric artery. In addition, in comparison study according to the injection route of ICG, The time to acquire signal stabilization was faster in central than in peripheral route (119 ± 65.1 seconds in central route vs. 295±130.4 in peripheral route, p<0.05).
NIR fluorescent images could provide the real-time information if there was ischemia or not in gastric tube during operation. And, central injection of ICG might give that information faster than peripheral route.
Pulmonary nodule could be identified by intraoperative fluorescence imaging system from systemic injection of indocyanine green (ICG) which achieves enhanced permeability and retention (EPR) effects. This study was performed to evaluate optimal injection time of ICG for detecting cancer during surgery in rabbit lung cancer model.
VX2 carcinoma cell was injected in rabbit lung under fluoroscopic computed tomography-guidance. Solitary lung cancer was confirmed on positron emitting tomography with CT (PET/CT) 2 weeks after inoculation. ICG was administered intravenously and fluorescent intensity of lung tumor was measured using the custom-built intraoperative color and fluorescence merged imaging system (ICFIS) for 15 hours. Solitary lung cancer was resected through thoracoscopic version of ICFIS.
ICG was observed in all animals. Because Lung has fast blood pulmonary circulation, Fluorescent signal showed maximum intensity earlier than previous studies in other organs. Fluorescent intensity showed maximum intensity within 6-9 hours in rabbit lung cancer. Overall, Fluorescent intensity decreased with increasing time, however, all tumors were detectable using fluorescent images until 12 hours.
In conclusion, while there had been studies in other organs showed that optimal injection time was at least 24 hours before operation, this study showed shorter optimal injection time at lung cancer. Since fluorescent signal showed the maximum intensity within 6-9 hours, cancer resection could be performed during this time. This data informed us that optimal injection time of ICG should be evaluated in each different solid organ tumor for fluorescent image guided surgery.
Since surface-enhanced Raman spectroscopy (SERS) makes it possible to enhance weak Raman signals which represent molecular own vibrational transition as a fingerprint, it has gotten much attention in the field of biosensor. Although SERS can detect specific molecules with high sensitivity and selectivity, it is still difficult to fabricate efficient SERS substrates, align ‘hot-spot’ with a detection site, and increase reproducibility for molecular sensing. Here, we converged plasmonic trapping with conventional SERS in order to overcome these drawbacks. As plasmonic trapping is to move nano particles toward the desired position by electric field gradient, we could trap gold nano particles (GNPs) onto a raw bowtie substrate and fabricate self-aligned hot-spots by using plasmonic trapping, which is directly contributed to enhancing weak signals by shortening structure-to-structure distances. Also, since a united laser was used to trap GNPs and to detect target molecules at the same time, it was possible to directly obtain Raman signal on the self-aligned hotspots. To further verify our technique, we also conducted numerical analysis for electric field distribution and trapping force by using finite element method and the results were well matched with the experimental data. This increases low reproducibility of SERS and as a result, we could repetitively obtain same results.
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