Conformal Virtual Colon Flattening

Wei Hong, Xianfeng Gu, Feng Qiu, Miao Jin and Arie Kaufman
Solid and Physics Modeling 2006

We present an efficient colon flattening algorithm using conformal structure, which is angle-preserving and minimizes the global distortion.

Moreover, our algorithm is general which can handle high genus surfaces. First, the colon wall is segmented and extracted from the CT dataset. The topology noise (i.e., minute handle) is located and removed automatically. The holomorphic 1-form, a pair of orthogonal vector fields, is then computed on the 3D colon surface

mesh using the conjugate gradient method. The colon surface is cut along a vertical trajectory traced using the holomorphic 1-form. Consequently, the 3D colon surface is conformal mapped to a 2D rectangle. The flattened 2D mesh is then rendered using a direct volume rendering method accelerated with the GPU. Our algorithm is tested with a number of CT datasets of real pathological cases, and gives consistent results. We demonstrated that the shape of the polyps is well preserved on the flattened colon images, which provides an efficient way to enhance the navigation of a virtual colonoscopy system.