Accurate Intervertebral Disc Localisation and Segmentation in MRI Using Vantage Point Hough Forests and Multi-atlas Fusion

An accurate method for localising and segmenting intervertebral discs in magnetic resonance (MR) spine imaging is presented. Atlas-based labelling of discs in MRI is challenging due to the small field of view and repetitive structures, which may cause the image registration to converge to a local minimum. To tackle this initialisation problem, our approach uses Vantage Point Hough Forests to automatically and robustly regress landmark positions, which are used to initialise a discrete deformable registration of all training images. An image-adaptive fusion of propagated segmentation labels is obtained by non-negative least-squares regression. Despite its simplicity and without using specific domain knowledge, our approach achieves sub-voxel localisation accuracy of 0.61 mm, Dice segmentation overlaps of nearly 90% (for the training data) and takes less than ten minutes to process a new scan.