Simulation of pneumoperitoneum for laparoscopic surgery planning.

Laparoscopic surgery planning is usually realized on a preoperative image that does not correspond to the operating room conditions. Indeed, the patient undergoes gas insufflation (pneumoperitoneum) to allow instrument manipulation inside the abdomen. This insufflation moves the skin and the viscera so that their positions do no longer correspond to the preoperative image, reducing the benefit of surgical planning, more particularly for the trocar positioning step. A simulation of the pneumoperitoneum influence would thus improve the realism and the quality of the surgical planning. We present in this paper a method to simulate the movement of skin and viscera due to the pneumoperitoneum. Our method requires a segmented preoperative 3D medical image associated to realistic biomechanical parameters only. The simulation is performed using the SOFA simulation engine. The results were evaluated using computed tomography [CT] images of two pigs, before and after pneumoperitoneum. Results show that our method provides a very realistic estimation of skin, viscera and artery positions with an average error within 1 cm.