Liver deformation in an animal model due to pneumoperitoneum assessed by a vessel-based deformable registration

Abstract

Purpose: Surgical navigation based on preoperative images partly overcomes some of the drawbacks of minimally invasive interventions - reduction of free sight, lack of dexterity and tactile feedback. The usefulness of preoperative images is limited in laparoscopic liver surgery, as the liver shifts due to respiration, induction of pneumoperitoneum and surgical manipulation. In this study, we evaluated the shift and deformation in an animal liver caused by respiration and pneumopertioneum using intraoperative cone beam CT. Material and methods: 3D cone beam CT scans were acquired with arterial contrast. The centerlines of the segmented vessels were extracted from the images taken at different respiration and pressure settings. A non-rigid registration method was used to measure the shift and deformation. The mean Euclidean distance between the annotated landmarks was used for evaluation. Results: A shift and deformation of 44.6 mm on average was introduced due to the combined effect of respiration and pneumoperitoneum. On average 91% of the deformations caused by the respiration and pneumoperitoneum were recovered. Conclusion: The results can contribute to the use of intraoperative imaging to correct for anatomic shift so that preoperative data can be used with greater confidence and accuracy during guidance of laparoscopic liver procedures.

Key words::

• Laparoscopy
• pneumoperitoneum
• deformable registration
• anatomic shift

Acknowledgments

This work was supported by the Marie Curie ITN project IIIOS (Integrated Interventional Imaging Operating System) project 238802, SINTEF Department of Medical Technology, the Ministry of Health and Social Affairs of Norway through the National Competence Centre for Ultrasound and Image-Guided Therapy (Trondheim, Norway), the project196726/V50 eMIT (enhanced Minimally Invasive Therapy) in the FRIMED program of the Research Council of Norway, and the Future Operating Room project at St. Olavs Hospital (Trondheim, Norway).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.