Branch identification method for CT-guided bronchoscopy based on eigenspace image matching between real and virtual bronchoscopic images

摘要

This paper presents a method for identifying branches for CT-guided bronchoscopy based on eigenspace image matching. This method outputs the current location of a real bronchoscope (RB) by displaying branches where a bronchoscope is currently observing or by presenting anatomical names of branches currently being observed. In the previous method of bronchoscope navigation, the motion of a real bronchoscope is tracked by image registration between RB and virtual bronchoscopic (VB) images. Although bronchoscope tracking based on image registration gives us very accurate tracking results, it requires a lot of computation time and it is difficult to perform real-time tracking. If we focus only on navigation to a target branch, it is enough to identify a branch where a bronchoscope is currently located. This paper presents a method for identifying branches in which a bronchoscope is currently observing and presenting their anatomical names. Branch identification is done by image matching between RB images and pre-generated VB images. VB images are pre-generated at each bifurcation point based on structural analysis results of bronchi regions extracted from CT images. For each frame of an RB video, we find the most similar VB image to the input one from a training dataset (pre-generated VB image) and output the branch levels associated with the found image by using the eigenspace method. We have applied the proposed method to a pair of comprising a 3D CT image and real bronchoscopic video. The experimental results showed that the proposed method can identify branches for about 77.7% of the input frames.