In the past several decades, medical imaging has made huge strides. The field of MRI in particular has seen huge advancements in technical capability, as recognized by a 2003 Nobel Prize in physiology/medicine and matched by an explosion in clinical use. Researchers continue to bring MRI to bear on new medical problems, continually expanding the range of conditions with which the technology can assist in diagnosis. Importantly, MRI does not share with x-ray or coherence tomography the safety risks inherent with ionizing radiation.