Development of endoscope navigation system based on 3D image recognition, understanding, and video image analysis

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The purpose of this research project is to develop a flexible endoscope navigation system, which guides a physician by presenting navigation information derived from pore-operative 3D medical images of each patient. The system is implemented as a fusion of real and virtual endoscopy system. We have developed the following elementary techniques that are required in the flexible endoscope navigation system : (1) flexible endoscope tracking, (2) techniques that are required for presenting anatomical structures beyond the wall currently observed, (3) methods for assisting flexible endoscopic examination and surgery.(1) Flexible endoscope trackingWe developed several methods for estimating flexible endoscopic camera motion from real endoscopic videos and preoperative CT scans. Here, three types of tracking methods were investigated : (a) direct camera motion estimation from video sequences by using epipolar geometry analysis, (b) camera motion estimation by frame-by-frame image registration between real and virtual endoscopic images (a kind of 2D/3D image registration), (c) camera motion prediction by Kalman filtering and its application for reducing computation time.(2) Anatomical structure display beyond the organ's wall being currendy observedIn the endoscopic navigation system, it is very important to display anatomical structure existing beyond the organ's wall being currently observed. For realizing this function, we developed several methods for segmenting each organ from input CT images. These segmentation results were visualized by using fast software-based volume rendering during endoscopic examinations.(3) Navigation information for assisting endoscopyWe investigated three methods for presenting navigation information as assistance of endoscopy : (a) automated anatomical labeling of bronchial trees, (b) detection of unobserved regions during endoscopy, and (c) information display using image deformation.