Chapter 5 30‐degree 10‐mm laparoscope applicable for both white light and near‐infrared fluorescence imaging. A foot pedal allows the surgeon to easily switch from conventional imaging to fluorescence imaging, and back. Procedures were digitally recorded. Preparation of near‐infrared fluorophore In these animal experiments, the system, which is primarily developed for indocyanine green (ICG) imaging, was now also tested for its feasibility for real‐time intraoperative fluorescence visualization of biliary anatomy (cystic duct and cystic artery) after intravenous administration of the pre‐clinical fluorescent dye CW800‐CA (a carboxylate of near‐infrared fluorophore IRDye® 800CW, LI‐COR, Lincoln, Nebraska). CW800‐CA was diluted in a sterile PBS solution. Surgical technique Premedication comprised of intramuscular injection of azaperone 3 mg/kg, ketamine 10 mg/kg and atropine 0.05 mg/kg. Anesthesia was induced with intravenous administration of thiopental 10‐15 mg/kg, intubated and maintained under anesthesia with isoflurane (depending on effect) and oxygen (20‐40 ml/kg/min). Thereafter a laparoscopy was performed. In each pig a laparoscopic cholecystectomy was performed, according to the Dutch Guidelines and best practice for laparoscopic cholecystectomy7, which is based on the Critical View of Safety technique. One experiment per animal was conducted. In the first two pigs 1 ml ICG (2.5 mg/ml Infracyanine®; SERB, France) was injected intravenously. This dose has proven sufficient for clinical use8. For the third experiment (pig no. 3) 5 mg of CW800‐CA was diluted in 20ml of PBS solution (0.25 mg/ml). One ml of this solution (0.25 mg) was intravenously administered. For the subsequent three experiments, 5 mg of CW800‐CA was diluted in 5 ml of PBS solution (1 mg/ml). Next, 1 ml (1.0 mg) of the solution was injected in pig no. 4. Three ml (3.0 mg) of the solution was administered in pig no. 5 and 6. Fluorescence imaging was obtained directly after dye injection and subsequently every 5‐10 minutes. Intraoperatively the researcher systematically registered on a form whether the localization of cystic duct or cystic artery could be identified at set time points, comparing the WL camera mode to ICG mode. For agreement on the identification of the aforementioned structures the attending surgeon was consulted. A structure was scored as ‘identified’ if its localization was confirmed with great certainty by the experienced surgeon. An overview of the six experiments is presented in Table 5.1. 68
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