Fast extraction of minimal paths in 3D images and applications to virtual endoscopy

The aim of this article is to build trajectories for virtual endoscopy insi de 3D medical images, using the most automatic way. Usually the constructio n of this trajectory is left to the clinician who must define some points o n the path manually using three orthogonal views. But for a complex structu re such as the colon, those views give little information on the shape of t he object of interest. The path construction in 3D images becomes a very te dious task and precise a priori knowledge of the structure is needed to det ermine a suitable trajectory. We propose a more automatic path tracking met hod to overcome those drawbacks: we are able to build a path, given only on e or two end points and the 3D image as inputs. This work is based on previ ous work by Cohen and Kimmel [Int. J. Comp. Vis. 24 (1) (1997) 57] for extr acting paths in 2D images using Fast Marching algorithm. Our original contribution is twofold. On the first hand, we present a gener al technical contribution which extends minimal paths to 3D images and give s new improvements of the approach that are relevant in 2D as well as in 3D to extract linear structures in images. It includes techniques to make the path extraction scheme faster and easier, by reducing the user interaction . We also develop a new method to extract a centered path in tubular structur es. Synthetic and real medical images are used to illustrate each contribut ion. On the other hand, we show that our method can be efficiently applied to th e problem of finding a centered path in tubular anatomical structures with minimum interactivity, and that this path can be used for virtual endoscopy . Results are shown in various anatomical regions (colon, brain vessels, ar teries) with different 3D imaging protocols (CT, MR). (C) 2001 Elsevier Sci ence B.V. All rights reserved.