Near-infrared fluorescence laparoscopy of the cystic duct and cystic artery: first experience with two new preclinical dyes in a pig model.

Background: Imaging techniques that enhance visualisation of the anatomy may help prevent bile duct injury. Near-Infrared Fluorescence Imaging is such a technique. Previous experiments with ICG have shown that illumination of the extra-hepatic bile ducts is feasible. Yet, there is room for improvement in the visualisation of the target as compared to the background. Experiments with IRDye 800CW show promising results. However, this dye is too expensive for routine clinical use. The aim of this study is to test the first applicability of two newly developed preclinical dyes regarding intraoperative imaging of the cystic duct and cystic artery, compared with IRDye 800CW.

Methods: Laparoscopic cholecystectomy was performed in three pigs, using a laparoscopic fluorescence imaging system. Each pig received 6 mg of one of the fluorescent dyes (1 mg/mL; IRDye 800CW, IRDye 800BK or IRDye 800NOS) by intravenous injection. Intraoperative recognition of the biliary system and cystic artery was registered at set time points. All procedures were digitally recorded, and the target to background ratio (TBR) was determined to assess the fluorescence signal.

Results: With all three fluorescent dyes, the cystic artery was directly visualised. For the visualisation of the cystic duct, 15, 34 and 30 min were needed using IRDye 800BK, IRDye 800NOS and IRDye 800CW, respectively. The maximum TBR of the cystic duct was the highest with IRDye 800NOS (4.20) after 36 min, compared to 2.45 for IRDye 800BK and 2.15 for IRDye 800CW, both after 45 min. There were no adverse events.

Conclusion: IRDye 800BK and IRDye 800NOS seem to be good alternatives for IRDye 800CW for the visualisation of the cystic duct and cystic artery in pigs.