Learning-based Object Detection in Cardiac MR Images

An automated method for left ventricle detection in MR cardiac images is presented. Ventricle detection is the rst step in a fully automated segmentation system used to compute volumetric information about the heart. Our method is based on learning the gray level appearance of the ventricle by maximizing the discrimination between positive and negative examples in a training set. The main di erences from previously reported methods are feature de nition and solution to the optimization problem involved in the learning process. Our method was trained on a set of 1,350 MR cardiac images from which 101,250 positive examples and 123,096 negative examples were generated. The detection results on a test set of 887 di erent images demonstrate an excellent performance: 98% detection rate, a false alarm rate of 0:05% of the number of windows analyzed (10 false alarms per image) and a detection time of 2 seconds per 256 256 image on a Sun Ultra 10 for an 8-scale search. The false alarms are eventually eliminated by a position/scale consistency check along all the images that represent the same anatomical slice.