The 20th International Conference on Information Processing in Medical Im- ing(IPMI)washeldduringJuly2–6,2007,atRolducAbbey,locatedinKerkrade in the south of the Netherlands. Following the highly successful IPMI in Gl- wood Springs in the Rocky Mountains, Colorado, USA (2005), the conference was the latest in a series of biennial scienti?c meetings where new developments in acquisition, analysis, and use of medical images are presented. IPMI is one of the longest running conferences in medical imaging. It was started in 1969 by a group of young scientists working in nuclear medicine. With a few iterations the conference expanded to other areas and became established as an important meeting for in-depth discussion of new methodological developments in me- cal imaging. Nowadays it is widely recognized as one of the most exciting and in?uential conferences in its ?eld. At IPMI meetings a wide variety of topics are covered by a relatively small selection of papers presented in single-track sessions. This year, there were 210 manuscripts submitted to the conference. Of these papers, 26 were accepted for oral presentation, and 37 papers were accepted as posters. Papers were ca- fully judged by three reviewers and two paper selection committee members, with emphasis on originality, methodological development, scienti?c rigor, and relevance. Selection of papers was di?cult, but using the rankings and detailed comments of the reviewerswe wereable to makea greatselectionin anobjective way. Unfortunately, due to the large number of submissions, it was inevitable that many high-quality papers did not make it into the ?nal program.