Mi2Wiki is a Wiki service which provides open source and collaborative efforts in in medical imaging informatics. It serves a virtual workspace to share research and education results and achievements in medical imaging informatics It provides a usefully platform not only to advocate the use of ontological descriptions of MII entities, but also to contribute each other's knowledge, vision, idea and presentations, as well as software tools in promoting the development of medical imaging informatic. It supports ontological descriptions of terms and terminologies used for future medical imaging informatics systems. It is based on both NBIRN and caBIG's infrastructure. It is compatible with NCBO's services and follows with NIH roadmap in the domain of medical imaging informatics.