Choledochoscopic Examination of a 3-Dimensional Printing Model Using Augmented Reality Techniques: A Preliminary Proof of Concept Study

Background. We applied augmented reality (AR) techniques to flexible choledochoscopy examinations. Methods. Enhanced computed tomography data of a patient with intrahepatic and extrahepatic biliary duct dilatation were collected to generate a hollow, 3-dimensional (3D) model of the biliary tree by 3D printing. The 3D printed model was placed in an opaque box. An electromagnetic (EM) sensor was internally installed in the choledochoscope instrument channel for tracking its movements through the passages of the 3D printed model, and an AR navigation platform was built using image overlay display. The porta hepatis was used as the reference marker with rigid image registration. The trajectories of the choledochoscope and the EM sensor were observed and recorded using the operator interface of the choledochoscope. Results. Training choledochoscopy was performed on the 3D printed model. The choledochoscope was guided into the left and right hepatic ducts, the right anterior hepatic duct, the bile ducts of segment 8, the hepatic duct in subsegment 8, the right posterior hepatic duct, and the left and the right bile ducts of the caudate lobe. Although stability in tracking was less than ideal, the virtual choledochoscope images and EM sensor tracking were effective for navigation. Conclusions. AR techniques can be used to assist navigation in choledochoscopy examinations in bile duct models. Further research is needed to determine its benefits in clinical settings.