Laparoscopic navigated liver resection: technical aspects and clinical practice in benign liver tumors

Abstract

Laparoscopic liver resection has been performed mostly in centers with an extended expertise in both hepatobiliary and laparoscopic surgery and only in highly selected patients. In order to overcome the obstacles of this technique through improved intraoperative visualization we developed a laparoscopic navigation system (LapAssistent) to register pre-operatively reconstructed three-dimensional CT or MRI scans within the intra-operative field. After experimental development of the navigation system, we commenced with the clinical use of navigation-assisted laparoscopic liver surgery in January 2010. In this paper we report the technical aspects of the navigation system and the clinical use in one patient with a large benign adenoma. Preoperative planning data were calculated by Fraunhofer MeVis Bremen, Germany. After calibration of the system including camera, laparoscopic instruments, and the intraoperative ultrasound scanner we registered the surface of the liver. Applying the navigated ultrasound the preoperatively planned resection plane was then overlain with the patient's liver. The laparoscopic navigation system could be used under sterile conditions and it was possible to register and visualize the preoperatively planned resection plane. These first results now have to be validated and certified in a larger patient collective. A nationwide prospective multicenter study (ProNavic I) has been conducted and launched.

Figure 1

3D MeVis data. (a) liver anatomy and tumor, (b) liver anatomy and portal veins, (c) liver anatomy, portal veins, and hepatic arteries, (d) potential resection plane.

Figure 2

(a–c) Screen shot of the LapAssistent with simultaneous presentation of (a) virtual reality navigation with registered intraoperative B-Mode ultrasound picture to the preoperative 3D-MRI-planning data, (b) real-time laparoscopic video screen imported from surgical laparoscopic imaging device, and (c) real-time ultrasound B-Mode picture with overlapping tumor.

Figure 3

System calibration under sterile conditions. (a) Pivot shift calibration, (b) rotating calibration.

Figure 4

Calibration of the camera. (a) Monitor picture, (b) virtually generated squares, (c) exposure of the squares to the camera, (d) calibrated camera view by definition of square crossings.

Figure 5

Calibration. (a) Calibration of the ultrasound device by placing it onto the calibrating phantom, (b) calibration process by registered strands in the calibrating phantom.

Figure 6

Intraoperative liver registration. (a) Positioning of the field generator beside the patient, (b) liver registration using four defined spots. The landmark on the left lobe is already activated.

Figure 7

LapAssistent placed intraoperatively on the right patient side; simultaneous laparoscopic and ultrasound scenes are described above.

Figure 8

Comparison of pre- and postoperative liver volume. (a) Preoperative 3D presentation of liver with portal venous and arterial vessels and tumor location. (b) Postoperative 3D presentation of liver with portal venous and arterial vessels.