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We present a novel approach to motion compensation for bronchoscope navigation where the bronchoscope trajectory is modeled using a spline curve. Initial position and orientation measurements from electromagnetic tracking are refined using the distance of the trajectory from airways segmented in preoperative CT data, and similarity between real and virtual bronchoscopic images. We present an evaluation on a dynamic motion phantom and on a moving ex-vivo porcine lung. Ground truth data is provided by human experts.

We present a novel approach to tracking of flexible bronchoscopes by modeling the output as spatially continuous over time. Bronchoscopy is a widespread clinical procedure for diagnosis and treatment of lung diseases and navigation systems are highly needed. Tracking of the bronchoscope can be regarded as a deformable registration problem. In our approach we use hybrid image-based and electromagnetic tracking, and the bronchoscope pose relative to CT data is interpolated using Catmull-Rom splines for position and SLERP for orientation. We evaluate the method using ground truth poses manually selected by experts, where mean inter-expert agreement was determined as 1.26 mm. For four dynamic phantom data sets, the accuracy of our method is between 4.13 and 5.93 mm and shown to be equivalent to previous methods.We significantly improve inter-frame smoothness from 2.35-3.08 mm to 1.08-1.51 mm. Our method provides a more realistic and physically plausible solution with significantly less jitter. This quantitative result is confirmed by video output, which is much more consistent and robust, with fewer occasions of tracking loss or unexpected movement.

Navigated bronchoscopy has been developed by various groups within the last decades. Systems based on CT data and electromagnetic tracking enable the visualization of the position and orientation of the bronchoscope, forceps, and biopsy tools within CT data. Therefore registration between the tracking space and the CT volume is required. Standard procedures are based on point-based registration methods that require selecting corresponding natural landmarks in both coordinate systems by the examiner. We developed a novel algorithm for a fully automatic registration procedure in navigated bronchoscopy based on the trajectory recorded during routine examination of the airways at the beginning of an intervention. The proposed system provides advantages in terms of an unchanged medical workflow and high accuracy. We compared the novel method with point-based and ICP-based registration. Experiments demonstrate that the novel method transforms up to 97% of tracking points inside the segmented airways, which was the best performance compared to the other methods.