  Magnetic Resonance Imaging (MRI) has become one of the most important tools
to screen humans in medicine, virtually every modern hospital is equipped with
an NMR tomograph. The potential of NMR in 3D imaging tasks is by far greater,
but there is only 'a handful' of MRI studies of particulate matter. The method
is expensive, time-consuming, and requires a deep understanding of pulse
sequences, signal acquisition and processing. We give a short introduction into
the physical principles of this imaging technique, describe its advantages and
limitations for the screening of granular matter and present a number of
examples of different application purposes, from the exploration of granular
packing, via the detection of flow and particle diffusion, to real dynamic
measurements. Probably, X-ray computed tomography is preferable in most
applications, but fast imaging of single slices with modern MRI techniques is
unmatched, and the additional opportunity to retrieve spatially resolved flow
and diffusion profiles without particle tracking is a unique feature.
