Image analysis has been strongly present in several healthgrid initiatives from the start, and today we find many imaging projects with successful grid implementations and developments. An example is the analysis of functional MRI data on grids, which has been successfully realized by several projects and that could be of interest for others. However, crossing the borders of existing grids is not trivial because the infrastructures being created for these projects differ, each adopting a (slightly) different software stack. This paper describes our early attempts to cross the borders between the German and Dutch grid infrastructures for medical imaging, motivated by a true wish to share expertise about fMRI analysis on grids between these two communities. We describe how we used off-the-shelf, production-level, grid technology to implement supporting mechanisms for cooperation in fMRI at several levels (users, data, software, workflows and computing resources). This simple exercise provided us valuable insights into the problems of crossing the borders of real grids from a user's perspective. Besides technical aspects, we observed that security and usability are very important for the success of inter-operation of Healthgrid.