Fluorescence cholangiography during laparoscopic cholecystectomy 45 Discussion This clinical report on the application of a newly developed laparoscopic fluorescence system during laparoscopic cholecystectomy shows that conducting real‐time intermittent fluorescence imaging of the extra‐hepatic bile ducts during laparoscopic gallbladder surgery is feasible. It provides a significantly earlier identification and a clear delineation (high TBR) of both common bile duct and cystic duct, therewith assisting in safe and efficient dissection of the gallbladder according to the CVS technique. Ishizawa et al.18 performed a study of fluorescent cholangiography in 52 laparoscopic cholecystectomies. By using a prototype fluorescent imaging system (Hamamatsu Photonics, Hamamatsu, Japan) coupled with a specially developed laparoscope the cystic duct could be identified intraoperatively in all subjects. In this study 1ml ICG (2.5 mg/ml Diagnogreen®; Daiichi Sankyo, Tokyo, Japan) was administered 30 minutes before the patient entered the operating theatre. In our study we injected the same dose of ICG, but after induction of anesthesia, which helps overcome logistical problems (e.g. no need to monitor the patient on the ward after ICG administration). Ishizawa et al.19 also tested their prototype system subsequently during single‐incision laparoscopic cholecystectomy (n=7), with promising outcomes for possible future implementation in this minimally invasive surgical technique. Differences with other studies are that we administered iodine‐free ICG (Infracyanine®) instead of iodinated ICG (e.g. Diagnogreen® 18‐20) and that the fluorescence signal is displayed in blue instead of green. Furthermore, in this study we conducted a ‘standardized application’ of NIRFC (i.e. every 5‐10 minutes switching to fluorescence imaging). To our knowledge such standardized implementation of fluorescent cholangiography has not been reported before. Compared with the other available laparoscopic fluorescence imaging system (Olympus Corp., Tokyo, Japan)9 the newly developed Karl Storz laparoscopic fluorescence imaging system offers the advantage that it is equipped with a foot pedal to switch between conventional and fluorescence imaging using the same laparoscope. A slight disadvantage of the current and the other available devices is that it does not yet possess the ability to real‐time overlay the NIRFC images with the conventional white light images. Another improvement could be contrast enhancement of Calot’s triangle during NIRFC imaging for even better delineation of the biliary tract. Quantitative fluorescence image analysis (e.g. TBR) as conducted in this study, could possibly be applied as a base for image enhancement. The present plasma light guide appeared quite rigid and in combination with the 30‐degree laparoscope sometimes inconvenient to handle during surgery. With respect to the hardware this requires modification.
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