Cardiac CT Angiography Image Reconstruction Presented by Saloni Goel M.Tech -CSE

Introduction The use of Content Adaptive Mesh model(CAMM) for Cardiac CT reconstruction is explored. Cardiac CT Angiography images are being reconstructed.

Problem Solution Approach Reconstruction of Cardiac CT Angiography Images Feature map extraction Adaptive Mesh- Node Placement Reconstruction of the image

Content-Adaptive Mesh Generation Mesh modeling of an image involves partitioning the image into a collection of non-overlapping (generally polygon) patches, called mesh elements. With a mesh model one can strategically place the mesh nodes more densely in regions containing significant features.

Sample Cardiac CT Angiography Image

Steps in Image Reconstruction Image is filtered using the Canny Edge Detection algorithm Floyd- Steinberg Error Diffusion algorithm is applied for the placement of mesh nodes. Mesh nodes are connected using Delaunay Triangulation algorithm. Iterative Reconstruction algorithms are applied so as to get the reconstructed image.

Feature Map Extraction Second derivatives are used for calculating the feature vector at any pixel. Then the following formulae is used to compute the feature map

Canny Edge Detection Algorithm preserving useful structural information about object. good detection the algorithm marks as many real edges in the image as possible. good localization edges marked are as close as possible to the edge in the real image. minimal response a given edge in the image should only be marked once, and where possible, image noise should not create false edges.

Our Finding We found that instead of using linear filtering i.e., second derivatives for filtering the image, the Canny Edge detection algorithm is far better to bring out the specific details about the image.

Adaptive Mesh- Node Placement Modified Floyd- Steinberg error diffusion algorithm used. Used for digital half-toning. Helps in placement of mesh nodes in accordance with the spatial density specified by the feature map .

Delaunay Triangulation algorithm Connects a given set of mesh nodes. the circle circumscribing any triangular element contains only the nodal points belonging to that triangle yields a well-structured mesh at a reasonable computational cost

Reconstruction of Image Iterative reconstruction algorithms applied. Maximum Likelihood and Maximum a Posteriori (MAP) algorithms being used for reconstructing the image with the help of the Content Adaptive Mesh Model

Image after filtering and error diffusion Results Original Image Image after filtering and error diffusion

Future Work We will extend the Reconstruction technique used here for reconstructing the 3D Cardiac CT Angiography Images. The 3D reconstructed image will help visualize the affected area more clearly. Which in turn will help in better diagnosis of the coronary blockage.

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