Virtual pneumoperitoneum for generating virtual laparoscopic images based on shape deformation

A method for performing a virtual pneumoperitoneum based on shape deformation and its application to virtual laparoscopy are described. Laparoscopic surgery is now widely performed as minimum-invasive surgery. Because a laparoscope has a very narrow viewing area, this limits the surgeon's viewable area. A virtual endoscopy system that provides virtual laparoscopic images rendered at arbitrary viewpoints and view directions to a surgeon during surgery would be very helpful for intra-operative surgical navigation or pre-operative surgical planning. Because CT images are taken before a pneumoperitoneum in most cases, the abdominal wall needs to be lifted for generating virtual laparoscopic images. We deform original 3-D abdominal CT images so that the abdominal wall is virtually elevated. The entire process consists of five major steps: (a) extracting the abdominal wall, (b) elastic modeling, (c) elastic deformation of the model, (d) deformation of the original image, and (e) rendering virtual laparoscopic images. Virtual laparoscopic images are then generated from the deformed image. We have applied the method to three cases of 3-D abdominal CT images. From the experimental results, we confirmed that the abdominal wall was appropriately elevated by the proposed method. Laparoscopic views generated were very helpful for intra-operative surgical navigation as additional views of a surgeon or pre-operative surgical planning.