New technology This section is designed to bring forward some of the latest innovative technology with explanations in terms that will clarify their importance to the discipline of surgery. Through the efforts of the Innovative Technology Committee of the Society of American Gastrointestinal Endoscopic Surgeons (SAGES), leading experts in various areas will be invited to present a summary of new technology, often including their pioneering work. Initial experience with stereoscopic visualization of three-dimensional ultrasound data in surgery A. Gronningsaeter, 1 T. Lie, 1 A. Kleven, 1 T. Mørland, 1 T. Langø, 1 G. Unsga ˚rd, 2 H. O. Myhre, 3 R. Ma ˚rvik 4 1 SINTEF Unimed, 7034 Trondheim, Norway 2 Neurosurgical Department, Faculty of Medicine, Norwegian Institute of Technology, 7005 Trondheim, Norway 3 Department of Surgery, Faculty of Medicine, Norwegian University for Science and Technology, 7005 Trondheim, Norway 4 National Center for Advanced Laparoscopic Surgery, University Hospital of Trondheim, 7006 Trondheim, Norway Received: 5 August 1999/Accepted: 14 October 1999/Online publication: 22 May 2000 Abstract. Initial in vivo and in vitro experiments were per- formed to evaluate the feasibility of stereoscopically dis- playing three-dimensional (3D) ultrasound data from neu- rosurgery, laparoscopic surgery, and vascular surgery. Ste- reoscopic visualization was illustrated by four video sequences, which can be downloaded from http:// www.us.unimed.sintef.no/. These sequences show a brain tumor, hepatic arteries in relation to the gallbladder, a model that mimics a neuroendoscope in a cyst, and a “flight” into model of an artery with an intima flap. The experiments indicate that stereoscopic display of ultrasound data is fea- sible when there is sufficient contrast between the objects of interest and the surrounding tissue. True 3D vision im- proves perception, thus enhancing the ability to understand complex anatomic structures such as irregular lesions and tortuous vessels. Key words: Image-guided surgery — Laparoscopy — Neu- rosurgery — Stereoscopic display — 3D Ultrasound — Vascular surgery In recent years, the rapid development in computer graphics and the increasing number of medical imaging methods cap- turing volumetric data have made display of three- dimensional (3D) reconstructions a valuable tool in many clinical applications. However, current standard displays such as computer and video screens and photographic and radiographic film all are two-dimensional (2D) modalities. Although various shading techniques can be incorporated to provide some depth cues, displaying 3D reconstructions in this standard 2D fashion inescapably robs the image of all true depth information. On a 2D screen, true 3D vision can be obtained only by displaying the data stereoscopically (i.e., providing the op- erator with two projections from two slightly different view angles such that each eye can only see one projection)[6]. The fundamentals of this technique, which constitutes the basis of virtual reality (VR), have a long tradition. In medi- cal imaging, a well-known example is viewing pairs of x- ray images captured from slightly different view angles through stereoscopic glasses. Whereas the making of an x-ray stereo projection requires two image acquisitions, 3D imaging methods allow for generation of an infinite number of stereoscopic projections from only one data acquisition. This increased versatility has disclosed a broad range of potential applications for stereoscopic visualization in medi- cine. Any reconstruction and display of 3D data requires a minimum of contrast between the object of interest and the surrounding tissue. Because the noisy and fuzzy nature of ultrasound images, imaging methods such as magnetic reso- nance imaging (MRI), computer tomography (CT), and digital subtraction angiography (DSA) usually are better suited for stereoscopic visualization than ultrasound. How- ever, with the development in image processing and 3D ultrasound technology, the interest for stereoscopic display of ultrasound data is increasing. Certain anatomic structures such as the liquid-filled cavities of blood vessels, cysts, ventricles, and abscesses, as well as lesions surrounded by a low echogenic media (some tumors and hematomas) pro- vide good contrast in ultrasound images. Recently, several investigators have demonstrated the feasibility of stereo- scopically displayed ultrasound images of breast tumors [5, 12] and cardiac structures [1, 9, 10]. The introduction of 3D ultrasound in surgery implies the need for convenient visualization techniques. Several appli- cations before, during, and after surgery require that the surgeon gets a good 3D perception of the anatomy. Cur- rently, we are investigating the use of stereoscopic visual- ization for this purpose, with emphasis on neurosurgery, laparoscopic surgery, and vascular surgery. This article Correspondence to: A. Gronningsaeter © Springer-Verlag New York Inc. 2000 Surg Endosc (2000) 14: 1074–1078 DOI: 10.1007/s004640000079