Augmented Reality Guided Laparoscopic Liver Resection: A Phantom Study With Intraparenchymal Tumors

Abstract

Introduction: Augmented reality (AR) in laparoscopic liver resection (LLR) can improve intrahepatic navigation by creating a virtual liver transparency. Our team has recently developed Hepataug, an AR software that projects the invisible intrahepatic tumors onto the laparoscopic images and allows the surgeon to localize them precisely. However, the accuracy of registration according to the location and size of the tumors, as well as the influence of the projection axis, have never been measured. The aim of this work was to measure the three-dimensional (3D) tumor prediction error of Hepataug.

Methods: Eight 3D virtual livers were created from the computed tomography scan of a healthy human liver. Reference markers with known coordinates were virtually placed on the anterior surface. The virtual livers were then deformed and 3D printed, forming 3D liver phantoms. After placing each 3D phantom inside a pelvitrainer, registration allowed Hepataug to project virtual tumors along two axes: the laparoscope axis and the operator port axis. The surgeons had to point the center of eight virtual tumors per liver with a pointing tool whose coordinates were precisely calculated.

Results: We obtained 128 pointing experiments. The average pointing error was 29.4 ± 17.1 mm and 9.2 ± 5.1 mm for the laparoscope and operator port axes respectively (P = 0.001). The pointing errors tended to increase with tumor depth (correlation coefficients greater than 0.5 with P < 0.001). There was no significant dependency of the pointing error on the tumor size for both projection axes.

Conclusions: Tumor visualization by projection toward the operating port improves the accuracy of AR guidance and partially solves the problem of the two-dimensional visual interface of monocular laparoscopy. Despite a lower precision of AR for tumors located in the posterior part of the liver, it could allow the surgeons to access these lesions without completely mobilizing the liver, hence decreasing the surgical trauma.

Keywords: Accuracy; Augmented reality; Hepatectomy; Laparoscopic; Pointing; Projection.