KEYWORDS: Stomach, Computed tomography, 3D image processing, 3D modeling, Image visualization, 3D image reconstruction, Visualization, Endoscopy, 3D acquisition, Image processing
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.
This paper describes a method for generating an unfolded view of organs based on elastic deformation. When we observe the inside of an organ that has a large cavity with a virtual endoscopy system,
the viewpoint and the view direction need to be changed many times. Unfolded views can visualize the entire organ wall at a glance and are very useful for diagnosis. The unfolding process requires creating a model that approximates the shape of the target organ. The approximated shape is generated from the outer wall of the organ by extracting the organ wall. The user interactively specifies a cutting line on the approximated shape. The stretching is performed by adding forces and calculating the elastic deformation. The volumetric image where the target organ is unfolded is reconstructed from the original image by using the relation between the approximated and the stretched shapes. We applied the proposed method to six 3-D abdominal CT images. The experimental results showed that the method generates adequate unfolded views of the target organs.
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