The use of the grey level SAT to find the salient cavities in echocardiograms

The aim of this work is to find out whether the grey level symmetric axis transform ( SAT) is a useful grey level shape description for finding the salient cavities in echocardiograms. The centres of the maximal discs of the grey level SAT are calculated using mathematical morphology as described by Peleg and Rosenfeld, and these centres are grouped to form symmetry surfaces. These surfaces are described as a graph in which each vertex has associated with it a description of a path from the top to the bottom of a symmetry surface, and two vertices are connected if their two paths are adjacent. The subgraphs of this graph which correspond to the salient cavities in the image are found by growing subgraphs from seed vertices. Finally, the boundaries of the cavities are reconstructed from these subgraphs. Our initial results are promising, although further work is needed to make the method more robust.