156 IEEE TRANSACTIONS ON INFORMATION TECHNOLOGY IN BIOMEDICINE, VOL. 2, NO. 3, SEPTEMBER 1998 The EASI Project—Improving the Effectiveness and Quality of Image-Guided Surgery M. Breeuwer, J. P. Wadley, H. L. T. de Bliek, J. Buurman, Member, IEEE, P. A. C. Desmedt, P. Gieles, F. A. Gerritsen, N. L. Dorward, N. D. Kitchen, B. Velani, D. G. T. Thomas, O. Wink, J. D. Blankensteijn, B. C. Eikelboom, W. P. Th. M. Mali, M. A. Viergever, G. P. Penney, R. Gaston, D. L. G. Hill, Member, IEEE, C. R. Maurer, D. J. Hawkes, F. Maes, D. Vandermeulen, R. Verbeeck, P. Suetens, Member, IEEE, G. Schmitz, T. M. Buzug, C. Lorenz, J. Sabczynski, J. Weese, W. Zylka, and M. H. Kuhn, Member, IEEE Abstract— In recent years, advances in computer technology and a significant increase in the accuracy of medical imaging have made it possible to develop systems that can assist the clinician in diagnosis, planning, and treatment. This paper deals with an area that is generally referred to as computer-assisted surgery, image- directed surgery, or image-guided surgery. We report the research, development, and clinical validation performed since January 1996 in the European Applications in Surgical Interventions (EASI) project, which is funded by the European Commission in their “4th Framework Telematics Applications for Health” program. The goal of this project is the improvement of the effectiveness and quality of image-guided neurosurgery of the brain and image- guided vascular surgery of abdominal aortic aneurysms, while at the same time reducing patient risks and overall cost. We have developed advanced prototype systems for preoperative surgical planning and intraoperative surgical navigation, and we have extensively clinically validated these systems. The prototype systems and the clinical validation results are described in this paper. Index Terms—Clinical validation, image-guided surgery, neu- rosurgery, software and hardware prototyping, vascular surgery. I. INTRODUCTION D URING the last few decades, various medical imaging techniques have become available, such as computed tomography (CT) and magnetic resonance (MR) imaging, Manuscript received April 15, 1998; revised August 10, 1998. This work was supported by the European Commission under Contract HC1012 in their “4th Framework Telematics Applications for Health” program. M. Breeuwer, H. L. T. de Bliek, J. Buurman, P. A. C. Desmedt, P. Gieles, and F. A. Gerritsen are with EasyVision Modules-Advanced Development, Philips Medical Systems Nederland B.V., 5680 DA Best, The Netherlands (marcel.breeuwer@best.ms.philips.com). J. P. Wadley, N. L. Dorward, N. D. Kitchen, B. Velani, and D. G. T. Thomas are with the National Hospital for Neurology and Neurosurgery London, The University Department of Neurosurgery, Institute of Neurology, WC1N 3BG London, U.K. O. Wink, J. D. Blankensteijn, B. C. Eikelboom, W. P. T. M. Mali, and M. A. Viergever are with Image Sciences Institute, Utrecht University and University Hospital AZU, 3584 CX Utrecht, The Netherlands. G. P. Penney, R. Gaston, D. L. G. Hill, C. R. Maurer, and D. J. Hawkes are with Guy’s, King’s and St. Thomas’ Hospitals Medical Schools, Division of Radiological Sciences and Medical Engineering, Computational Imaging Science Group, King’s College London, SE1 9RT London, U.K. F. Maes, D. Vandermeulen, R. Verbeeck, P. Suetens are with the Laboratory for Medical Imaging Research, Radiology—ESAT, Katholieke Universiteit Leuven, B-3001 Heverlee, Belgium. G. Schmitz, T. M. Buzug, C. Lorenz, J. Sabczynski, J. Weese, W. Zylka, and M. H. Kuhn are with the Technical Systems Division, Philips Research Laboratories, D-22335 Hamburg, Germany. Publisher Item Identifier S 1089-7771(98)08543-4. which can be used as an aid in diagnosing pathologies and planning medical treatment. Diagnosing was first performed in a “visual manner:” the clinician compared what he/she perceived visually in the medical images with his/her knowl- edge of anatomy and pathology. Planning of treatment was performed in a similar way. Prior to surgery, for example, the surgeon used the medical images to project in his/her mind the three-dimensional (3-D) patient’s anatomy and determined the surgical plan on the basis of this “mental projection.” In recent years, advances in computer technology and a significant increase in the accuracy of imaging have made it possible to develop systems that can assist the clinician in diagnosis, planning, and treatment. This paper deals with an area that is generally referred to as computer-assisted surgery, image-directed surgery, or image-guided surgery (the last term will be used throughout this paper) [1]–[5]. The principle of image-guided surgery is as follows. Prior to surgery, images of the regions of interest in the patient are acquired (henceforth denoted as preoperative imaging) and these images are used to plan surgery. This preoperative planning may involve the application of advanced image processing and visualization techniques to segment and visualize various structures (bloods vessels, tumor tissue, etc.). In the operating theater, the pre- operatively acquired images are registered to the patient. During surgery, the position of surgical instruments is tracked and displayed in the preoperative images, which enables the surgeon to accurately navigate through the area of interest in the patient. In January 1996, the European Applications in Surgical Interventions (EASI) project started. In this three-year project, which is supported by the European Commission in their “4th Framework Telematics Applications for Health” program, research, development and clinical evaluation in the area of image-guided surgery are performed. This paper reports the achievements of this project. We intend to provide an overview and will therefore not give a great amount of detail. We mainly describe what has been developed for which specific reasons. Furthermore, results of the clinical evalua- tion of the developed tools are briefly discussed. References to papers with more detailed background information are given. The remainder of the paper is structured as follows. First, in Section II, the objectives of the EASI project and the approach 1089–7771/98$10.00  1998 IEEE