"Pulmonary Image Registration With elastix Using a Standard Intensity-Based Algorithm"
Marius Staring, Stefan Klein, Johan H.C. Reiber, Wiro J. Niessen and Berend C. Stoel
Accurate registration of thoracic CT is useful in clinical terms and also challenging due to the elastic nature of lung tissue deformations. The goal of the EMPIRE10 challenge (Evaluation of Methods for Pulmonary Image Registration 2010), a workshop of the MICCAI 2010 conference, is to provide a platform for in-depth evaluation and fair comparison of available registration algorithms for this application. To this end we registered to the challenge with team RubberBand. The goal of our submission is to determine what a standard, but fully automatic, intensity-based image registration algorithm can achieve compared to the competition. The algorithm, implemented in elastix, optimises the normalised correlation criterion, using a fast, parameter-free and robust stochastic optimisation procedure. A combination of an affine and two nonrigid B-spline transformations models the spatial relationship. The approach is embedded in a multi-resolution framework for both the image data and the transformation. No explicit regularisation is used. Of the 34 submitted algorithms, our contribution achieved the 7-th place with an average rank of 13.13 (best 8.03, worst 31.46). The incorporation of a regularisation term may improve the ranking of the algorithm, since our final score was most negatively influenced by the score for folding.