Abstract
As advances in research and technology continue to reduce rates of morbidity and mortality in patients undergoing major liver surgery, there is a strong interest in moving toward more complex cases with extended tumor spread that would otherwise be considered nonoperable. This endeavor shows promise with the advent of intraoperative navigation systems. Currently, selection of patients and surgical planning for hepatic resections are based in large part on computed tomography or sometimes magnetic resonance imaging. Based on these images and the additional information gained by the palpating hand and intraoperative ultrasound, the operative resection plans are made. With the increasing use of ablative procedures and laparoscopy, intraoperative imaging and navigation will hold increasing significance for the hepatobiliary-pancreatic surgeon. With the navigation system, monitors adjacent to the surgical field display computer-generated three-dimensional virtual liver resection proposals, which can be executed onto the real liver. An intended resection can be performed virtually, and the influence of different resection planes on blood supply and drainage within the remaining liver parenchyma can be calculated by a computer-assisted risk analysis; thus, the surgeon may optimize the functional level of the remnant liver. Although computer-assisted imaging and navigation has mostly been used for extended hepatic resection for tumors, it also plays an important role in operative planning for live-donor liver transplantation.
In this review, Donati et al. 1 briefly discuss the goals of navigation, methods of acquiring images to build a three-dimensional map of the liver, the navigation systems available, and unsolved problems in navigation for liver surgery. The authors summarize the challenges that navigation must overcome before it can become established in routine clinical practice for liver surgery. At present, more effort will need to be directed toward achieving greater precision and overcoming concomitant real-time deformation of the model during surgical manipulation of the liver, as well as the shift in localization that occurs with brief movements of the liver during surgical resection, such as with breathing movements. In the future, a fusion of navigation techniques may facilitate a continuous recording of the three-dimensional image to overcome these problems. Video-dependence of surgeons must also be addressed with further development of optional audio-feedback. The millimetric correspondence between reconstructed anatomy and real anatomy must narrow (currently a middle error of about 1 cm) before even the best surgical cases are considered on a routine basis. In addition to the challenges presented in this article, development of navigation support functionalities according to defined surgical problems is needed because generic surgical navigation applications will not be able to adjust to complex clinical scenarios, workflows, and individual treatment options. Also, for magnetic resonance imaging–based navigation systems, which allow for real-time visualization of pathology and delineation of internal architectural changes during treatment, the remaining challenge will be to lower cost and space occupancy in the operation room. After achieving these goals, randomized control studies will need to demonstrate superiority of navigation systems over current practice.
The development of navigation techniques in liver surgery has huge potential for hepatobiliary surgeons to more strategically plan their operative procedures and execute them with more precision.
This article 1 is a concise description of the navigation technology in liver surgery and some of the challenges that remain to be tackled before completely navigated soft-tissue surgery goes from being an object of desire to one of reality.