Image-guided surgery - Preliminary feasibility studies of frameless stereotactic liver surgery

Background: Liver surgery can be difficult because there are few external l andmarks defining hepatic anatomy and because the liver has significant vas cularity. Although preoperative tomographic imaging (computed tomography or magnetic resonance imaging) provides essential anatomical information for operative planning, at present it cannot be used actively for precise local ization during surgery. Interactive image-guided surgery involves the simul taneous real-time display of intraoperative instrument location on preopera tive images (computed or positron-emission tomography or magnetic resonance imaging). Interactive image-guided surgery has been described for tumor lo calization in the brain (frameless stereotactic surgery) and allows for int eractive use of preoperative images during resections or biopsies. Hypothesis: The application of interactive image-guided surgery (IIGS) is f easible for hepatic procedures from a biomedical engineering standpoint. Methods: We developed an interactive image-guided surgery system for liver surgery and tested a porcine liver model for tracking liver motion during i nsufflation; liver motion during respiration in open procedures in patients undergoing hepatic resection; and tracking accuracy of general surgical in struments, including a laparoscope and an ultrasound probe. Results: Liver motion due to insufflation can be quantified; average motion was 2.5 +/- 1.4 mm. Average total liver motion secondary to respiration in patients was 10.8 +/- 2.5 mm. Instruments of varying lengths, including a laparoscope, can be tracked to accuracies ranging from 1.4 to 2.1 mm within a 27-m(3) (3 X 3 X 3-m) space. Conclusion: Interactive image-guided surgery appears to be feasible for ope n and laparoscopic hepatic procedures and may enhance future operative loca lization.