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


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.


CONCLUSIONS
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.
Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU) , Trondheim , Norway.
Sinara
S
Vijayan
Ingerid
I
Reinertsen
Erlend Fagertun
EF
Hofstad
Anna
A
Rethy
Toril A Nagelhus
TA
Hernes
Thomas
T
Langø
D000818:Animals; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D004195:Disease Models, Animal; D021621:Imaging, Three-Dimensional / Q000379:methods; D010535:Laparoscopy / Q000379:methods*; D008099:Liver / Q000378:metabolism / Q000601:surgery*; D016343:Monitoring, Intraoperative / Q000379:methods; D011027:Pneumoperitoneum / Q000503:physiopathology*; D012119:Respiration; D013552:Swine
Laparoscopy; anatomic shift; deformable registration; pneumoperitoneum