Detection of stable mammographic features under compression using simulated mammograms

Stable features under simulated mammographic compressions, which will become candidate landmarks for a temporal mammographic feature-based registration algorithm, are discussed in this paper. Using these simulated mammograms, we explore the extraction of features based on standard intensity projection images and local phase projection images. One approach to establishing corresponding features is by template matching using a similarity measure. Simulated mammographic projections from deformed MR volumes are employed, as the mean projected 3D displacements are computed and therefore validation of the technique is possible. Tracking is done by template matching using normalized cross correlation as the similarity measure. The performance of standard projection images and local phase projection images is compared. The preliminary results reveal that although the majority of the points within the breast are difficult to track, a small number may be successfully tracked, which is indicative of their stability and thus their suitability as candidate landmarks. Whilst matching using the standard projection images achieves an overall error of 14.46mm, this error increases to 22.7mm when computing local phase of the projection images. These results suggest that using local phase alone does not improve template matching. For the identification of stable landmarks for feature-based mammogram registration, we conclude that intensity based template matching using normalized correlation is a feasible approach for identifying stable features.