226 Sphenoidal Sinus Nasal Septum Tumor Nasal cavity Optical Nerve Sphenoidal Sinus Nasal Septum Tumor Nasal cavity Optical Nerve Image stitching of sphenoid sinuses from monocular endoscopic views T. Bergen 1 , P. Hastreiter 2 , C. Münzenmayer¹, M. Buchfelder 2 , T. Wittenberg 1 ¹ Fraunhofer Institute for Integrated Circuits IIS, Erlangen, Germany ² Department for Neurosurgery, University Clinics Erlangen, Germany Contact: thomas.wittenberg@iis.fraunhofer.de Abstract: For operations of the pituitary glands, the most subtle method is an intervention through the paranasal and especially through the sphenoid sinus. To avoid dangerous interference with adjacent organs and nerves, the surgeon has to orient himself in the very small sphenoid cavity and navigate across the hollow space to break through the sellar floor to the pituitary gland above. Especially in reoperations or anatomical variants such as so-called kissing carotids, transsphenoidal surgery is a challenge even in experienced hands. To support such a surgery, various imaging modali- ties can be applied such as CT, MRI or endoscopy. While pre-operative MRI or CT-data can be used for intervention planning and navigation support, endoscopy can be applied intra-operatively for the examination of surfaces inside the sphenoid sinus. In this work, we present initial experiments and results from real-time panorama-endoscopy of the sphenoid sinus for navigation and orientation support, based on monocular endoscopic sequences of a skull phantom, yielding partial reconstructions of the walls of the sphenoid sinus. Key words: pituitary surgery, sinus surgery, panorama-endoscopy, stitching, mosaicking, real-time 1 Introduction The most subtle method for operations of the pituitary glands, such as the removal of tumors or adenomas, is transsphenoidal surgery. This involves the difficulty of maneuvering through the paranasal and especially the sphenoid sinus, a small cavity behind the eyes, to break through the sellar floor and gain access to the pituitary gland. This is a difficult operation due to the risk of damaging adjacent nerves and organs, such as the internal carotid artery. depicts the situation in a CT slice. Various imaging modalities can be applied to support the surgeon, including e.g. CT, MRI or endoscopy. CT and MRI are available in the pre-operative planning phase. The standard imaging mo- dality during the operation is the view through an endoscope. One major as- pect of difficulty is the limited field of view provided by the endoscope. To improve orientation and maneuverability for the surgeon, image stitching techniques can be applied to provide an augmented field of view. In this pa- per, we propose a real-time panorama-imaging approach for navigation and orientation support, based on monocular endoscopic sequences of a skull phantom, yielding partial reconstructions of the walls of the sphenoid sinus. These experiments are based on prior experiences, gained from a 3D recon- struction approach from endoscopic views [1]. Further work concerning view enhancement in sinus surgery includes registration techniques for CT/endoscopy registration by Burschka et al. and Mirota et al. [2, 3]. Wise and DelGaudio as well as Palmer and Kennedy provide review articles of computer-assistance in paranasal sinus surgery [4, 5]. Different aspects of navigation and registration of pre- and intra-operative imaging techniques are discussed as a means of facili- tating orientation for the surgeon. However, panorama-endoscopy has not yet been considered in the field of sinus sur- gery. Figure 1: Transnasal approach to the tumor in the pituitary gland, depicted in an axial CT slice of a head.