A method for generating unfolded views of the stomach based on volumetric image deformation

This paper presents a method for virtually generating unfolded views of the stomach using volumetric image deformation. When we observe an organ with a large cavity in it, such as the stomach or the colon, by using a virtual endoscopy system, many changes of viewpoint and view direction are required. If virtually unfolded views of a target organ could be generated, doctors could easily diagnose the organ's inner walls only by one or a several views. In the proposed method, we extract a stomach wall region from a 3-D abdominal CT images and the obtained region is shrunken. For every voxel of the shrunken image, we allocate a hexahedron. In the deformation process, nodes and springs are allocated on the vertices, edges, and diagonals of each hexahedron. Neighboring hexahedrons share nodes and springs, except for the hexahedrons on the cutting line that a user specifies. The hexahedrons are deformed by adding forces that direct the nodes to the stretching plane to the nodes existing on the cutting line. The hexahedrons are deformed using iterative deformation calculation. By using the geometrical relations between hexahedrons before and after deformation, a volumetric image in which the stomach region is unfolded. Finally, the unfolded views are obtained by visualizing the reconstructed volume can be constructed. We applied the proposed method to eleven cases of 3-D abdominal CT images. The results show that the proposed method can accurately reproduce folds and lesions on the stomach.