The alignment of medical images is an ongoing topic of research. Early attempts date back as far as the early 1970s (e.g. Dowsett and Perry, A comparative statistical analysis of brain scans using a digital computer, BJR 1970). Still, to this day new challenges arise in the clinical workflow that require further development and improvement of registration methods. The focus of image registration research is on methodological innovation, both to improve techniques and to further application of registration in clinical problems. Some example results from past research include work on mutual information (1, 2), approaches that incorporate knowledge to improve registration (3, 4), a method to automatically determine registration quality locally in a pair of images (5), atlas-based segmentation techniques (6, 7), a tool to quickly produce reference standards for image registration in a semi-automatic fashion (8, isimatch) and an open source package for registration, elastix.