Chapter 5 ICG (also at 800 nm). However, after intravenous injection it is not only rapidly cleared by the liver and excreted into bile, but also by the kidneys and excreted into the urine. As a result this dye is eligible for imaging of the biliary anatomy and of the ureters9. Previously Tanaka et al. tested ICG and CW800‐CA for bile duct imaging in rats and pigs5 during open surgery. CW800‐CA proved to be more selective, as ICG suffered from lack of efficient secretion into bile from the liver. In addition, CW800‐CA was excreted into bile in a predominantly unmetabolized form, which increases the rapidity and signal intensity by which images can be obtained after administration. In the present study, CW800‐CA dosage in the first experiment was based on the report by Tanaka et al.5. A dose of 7.5 g/kg bodyweight appeared not sufficient for laparoscopic fluorescence detection of the cystic duct and artery. With a significantly higher dose (85 g/kg) of the injected dye, clear visualization of the course of the cystic duct and artery was obtained in this study. Furthermore, from this study it was noticed that time from injection until fluorescence identification of the cystic duct was reduced when CW800‐CA was used compared to ICG (respectively 11.5 versus 21.5 minutes). Based on target‐to‐back‐ground‐ratios this study demonstrates the ability of identifying the cystic duct after injection of both fluorophores. Regarding arterial fluorescence imaging, background signal (i.e. dye uptake by the liver parenchyma) was more profound when ICG was used, compared to CW800‐CA. Therefore recognition of the cystic artery might be easier with CW800‐CA. Besides laparoscopic cholecystectomy, fluorescence imaging of crucial biliary structures might be beneficial in other (laparoscopic) hepato‐pancreato‐biliary (HPB) surgical procedures as well. Possible applications of this technique during HPB surgery include tumor detection in liver and pancreas resections, and real‐time imaging of intra‐ and extra‐hepatic bile ducts and (branches of) hepatic, cystic, pancreatic, gastroduodenal and pancreatoduodenal arteries10‐12. Moreover, fluorescence imaging could be performed to detect bile leakage during open and laparoscopic partial liver resections. This complication after hepatectomy occurs in approximately 8% of all patients undergoing partial liver resection and is associated with greater postoperative mortality and health care costs13. Prevention of bile leakage after hepatectomy therefore deserves attention. A randomized clinical trial evaluated the use of ICG fluorescence cholangiography to prevent postoperative bile leakage after hepatic resections. The ability to detect leaking bile duct stumps at the cut surface of the remnant liver, which were missed by conventional bile leak tests, was demonstrated14. Given its pharmacokinetics, CW800‐CA might prove to be even more suitable for the detection of bile leakage. Although this report only describes a small experimental animal study and a large difference in dosage of CW800‐CA, the concept of fluorescence visualization of the 72
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