In the experimental study of the mechanics of granular media, x-ray tomography combined with 3D image analysis is finally opening the way for studies at the grain scale. Recent work shows that all the grains in a specimen containing several tens of thousands of grains can be successfully followed throughout deformation, allowing micro-mechanical interpretation of behaviour observed at the macro-scale. There are practical issues when trying to measure grain-to-grain contacts (i.e., identification of contacts and measurement of their orientation) from the same tomography images, however, these are an essential ingredient for a more profound understanding of the micro-mechanics of deformation. In this paper, we present a short selection of " mature " grain-scale measurements and then discuss the challenges associated with grain-to-grain contacts. Results from ongoing work show that very advanced image analysis techniques can allow this measurement to be made successfully, even when grains surfaces are not imaged at high resolution.