Evaluation of real-time infrared intraoperative cholangiography in a porcine model

Background: Intraoperative cholangiograms (IOCs) may increase cost, surgical time, and radiation exposure of staff and patients. The authors introduce the application of passive infrared imaging to intraoperative cholangiography as a feasible alternative to traditional fluoroscopic IOCs. Methods: A porcine model was used in which the gallbladder, cystic duct, common bile duct (CBD), and duodenum were exposed and an 18-gauge angiocatheter was inserted into the cystic duct. Infrared emission was detected using a digital infrared camera positioned 30 to 60 cm above the abdomen. Infrared images were taken in real time (∼1/s) during infusion of room-temperature saline. A thermoplastic polymer stone then was inserted into the CBD. Once the artificial stone was placed, room-temperature saline was again injected. A standard single-shot renograffin IOC was obtained to confirm the obstruction. The experiment was concluded by creation of a lateral 2-mm CBD injury immediately proximal to the duodenum followed by infusion of room-temperature saline. Results: Six pigs were used in this study. Baseline infrared imaging was able to capture a visible temperature decrease, outlining the lumen of the CBD. With injection of room-temperature saline, a decrease in temperature was visualized as a dark area representing flow from the CBD to the duodenum. After placement of the synthetic stone, real-time infrared images displayed slowing of the injected bolus by the obstruction. The obstruction was correlated with fluoroscopic IOCs. Finally, after partial transection of the CBD, the infrared camera visualized saline flowing from the site of injury out into the peritoneal cavity. Conclusions: The CBD anatomy, obstruction, and injury can be clearly visualized with an infrared camera. Intraoperative infrared imaging is an emerging method already being used in several surgical fields. Ultimately, the integration of infrared and laparoscopic technology will be necessary to make infrared technology important in laparoscopic cholecystectomy.