INFRASTRUCTURE FOR IMAGE GUIDED SURGERY 1 Abstract — Image guided surgery (IGS) requires an integrated environment for seamless acquisition, visualization, manipulation, display, registration and storage of complex data sets. The infrastructure to support IGS integrates image acquisition, networks, presurgical planning, surgical navigation, and archival storage elements. This paper describes the principal components of an integrated IGS environment and an implementation in a large academic medical center. The IGS infrastructure is illustrated for practical applications in neurosurgical case examples. Index Terms -- imaging, image storage, image transmission, medical image processing I. I NTRODUCTION mage guided surgery (IGS) requires image acquisition, visualization, surgical planning, navigation, and archival data storage. The purpose of this paper is to identify the requirements for IGS and introduce an integrated environment for IGS support. This infrastructure was implemented and is used daily for image guided neurosurgery and orthopedic surgery at the University of Iowa Hospitals and Clinics. Several case examples of image guided neurosurgery are shown to demonstrate the application of this infrastructure . The visualization and review of medical images, as well as surgical planning can be completed on personal computers with intranet and internet connections to a surgery-dedicated server. After surgical planning images are delivered from the server to the operating room, the patient anatomy is registered with the images and surgical navigation begins. Most image guided surgical procedures require preoperative 3D MRI or CT images. Other imaging modalities such as positron emission tomography (PET), ultrasound, and computed radiography can be used as the primary imaging modality, or to augment information provided by CT and MRI. These digital images are delivered from scanners to surgical planning workstations and Manuscript submitted June 28, 2001. This work was supported in part by the National Institute of Neurological Disease and Stroke, National Institute of Health Grant No. 5R01NS35368-05. J. W. Haller is with the Department of Radiology, University of Iowa College of Medicine, Iowa City, IA 52242 USA (telephone: 319-356- 2768, e-mail: john-haller@uiowa.edu). T. C. Ryken is with the Department of Neurosurgery, University of Iowa College of Medicine, Iowa City, IA 52242 USA (telephone: 319- 356-3853, e-mail: timothy-ryken@uiowa.edu). T. A. Gallagher is at Loyola University Stritch School of Medicine, Chicago, IL, USA (email: tgalla1@wpo.it.luc.edu) M. W. Vannier is with the Department of Radiology, University of Iowa College of Medicine, Iowa City, IA 52242 USA (telephone: 319- 356-3371, e-mail: michael-vannier@uiowa.edu). specialized workstations used to guide surgery in the operating room (figs. 1, 4-6, and 10). Successful everyday application of this technology requires specialized infrastructure that shares many components with a radiology departmental picture archiving and communication system (PACS). A system is introduced here which describes an integrated environment that supports workflow from CT and MRI scanners to radiologist to surgeon based on preoperatively gathered 3D images. Surgical planning requires visualization and analysis performed on a variety of networked workstations, which may include a home PC. The delivery of image guided surgery in the operating room is done with navigation appliances that match the surgical plan with the patient’s anatomy in a controlled environment. Superimposition of multiple scans and interaction with specialized workstations is integrated into the surgical procedure. Images can also be acquired during the surgery using MRI, ultrasound or other imaging devices to update the information as the surgery proceeds. A cost-effective and important new innovation is real time fusion of ultrasound images with 3D models of the patient’s anatomy created from CT and/or MRI. The ultrasound images serve to update the information provided by MRI and CT images but require instant multimodality fusion to be useful. II. IMAGE GUIDED SURGERY NETWORKS & METHODS A. Image Acquisition Modern radiology departments have CT and MRI scanners. The multislice CT and MRI scanner with fast gradients are used to collect preoperativ e images. All of these images must be transmitted via digital imaging communication (DICOM) interfaces to the PACS archive and into the image guided surgery network. The connectivity of scanners and PACS interfaces are, from a practical perspective, the most important aspects of scanners for image guided surgery. Almost any scanner, suitably connected and interfaced, can provide the data needed for image guided surgery once appropriate protocols and calibration procedures have been established. Technologists who operate the scanners use standard 3D imaging protocols that make these image guided procedures reliable and useful. B. Image Networks Successful implementation of image guided surgery on a large scale requires specialized infrastructure, especially a high performance network, that is mapped onto the hospital’s PACS. In a research environment, the network must have specialized distributed storage for critical and immediate access to key images. Flexibility in the network and its components is Infrastructure for Image Guided Surgery John W. Haller, Timothy C. Ryken, Thomas A. Gallagher and Michael W. Vannier I