R. Larsen, M. Nielsen, and J. Sporring (Eds.): MICCAI 2006, LNCS 4190, pp. 347 – 354, 2006. © Springer-Verlag Berlin Heidelberg 2006 Simultaneous Stereoscope Localization and Soft-Tissue Mapping for Minimal Invasive Surgery Peter Mountney 1 , Danail Stoyanov 1 , Andrew Davison 1 , and Guang-Zhong Yang 1,2 1 Royal Society/Wolfson Foundation Medical Image Computing Laboratory, 2 Department of Surgical Oncology and Technology Imperial College, London SW7 2BZ, UK {peter.mountney, danail.stoyanov, andrew.davison, g.z.yang}@imperial.ac.uk http://vip.doc.ic.ac.uk Abstract. Minimally Invasive Surgery (MIS) has recognized benefits of reduced patient trauma and recovery time. In practice, MIS procedures present a number of challenges due to the loss of 3D vision and the narrow field-of-view provided by the camera. The restricted vision can make navigation and localization within the human body a challenging task. This paper presents a robust technique for building a repeatable long term 3D map of the scene whilst recovering the camera movement based on Simultaneous Localization and Mapping (SLAM). A sequential vision only approach is adopted which provides 6 DOF camera movement that exploits the available textured surfaces and reduces reliance on strong planar structures required for range finders. The method has been validated with a simulated data set using real MIS textures, as well as in vivo MIS video sequences. The results indicate the strength of the proposed algorithm under the complex reflectance properties of the scene, and the potential for real-time application for integrating with the existing MIS hardware. 1 Introduction In surgery, the increasing use of MIS is motivated by the benefit of improved therapeutic outcome combined with reduced patient trauma and hospitalization. The technique is increasingly being used to perform procedures that are otherwise prohibited by the confines of the operating environment. MIS also offers a unique opportunity for deploying sophisticated surgical tools that can greatly enhance the manual dexterities of the operating surgeon. Despite the benefit of MIS in terms of patient recovery and surgical outcome, the practical deployment of the technique is complicated by the complexity of instrument control and difficult hand-eye coordination. Due to the large magnification factors required for performing MIS tasks, the field-of-view of the laparoscope cameras is usually very limited. This results in restricted vision which can affect the visual-spatial orientation of the surgeon and the awareness of the peripheral sites. In order to facilitate the global orientation of the target site, a number of spatial localization techniques have been developed. These include the use of pre-operative imaging combined with 2D/3D registration such that the underlying structure and morphology of the soft-tissue can be provided. To cater for tissue deformation,