Fluorescent cholangiography in a mouse model: an innovative method for improved laparoscopic identification of the biliary anatomy

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Abstract
Real-time imaging of the biliary anatomy may facilitate safe and timely completion of laparoscopic cholecystectomy. This study sought to determine whether the unique autofluorescent properties of bile could facilitate intraoperative identification of the biliary anatomy in mice using fluorescent cholangiography. Fluorimetry was performed on samples of mouse bile to determine excitation and emission spectra. For seven mice, chevron laparotomy was performed, followed by liver retraction to expose the porta hepatis. Using stereomicroscopy, photographs were taken in brightfield and fluorescent modes without a change in depth or focus. Six surgical residents evaluated the pictures and identified the gallbladder, cystic duct, common bile duct, and whether the cystic duct joined the right hepatic duct or the common bile duct. Fluorimetry demonstrated autofluorescence of bile at an excitation wavelength of 475 nm. Intense emission was observed at 480 nm. At these settings, fluorescent stereomicroscopy easily identified the gallbladder and biliary tree in mice. This technique decreased diagnostic errors of the biliary anatomy 11-fold (2% vs 22%; p < 0.01), as compared with brightfield visualization. Fluorescent stereomicroscopy also was used to diagnose bile leak, obstruction, and complex anatomy. Using a prototype 5-mm laparoscope equipped with fluorescent filters, the results were reproduced. Fluorescent cholangiography based solely on the autofluorescence of bile may facilitate real-time identification of the biliary anatomy during laparoscopic procedures, without the need for extraneous dye administration or the use of radiography. This technique has the potential to decrease the rate of iatrogenic biliary tract injuries during laparoscopic cholecystectomy.