Magnetic Resonance Imaging (MRI), medical imaging technique most commonly used in radiology to visualize the internal structure and function of the body. MRI provides much greater contrast between the different soft tissues of the body, making it especially useful in neurological (brain), musculoskeletal, cardiovascular, and oncological (cancer).
CT scans (Cat Scans) of internal organs, bone, soft tissue and blood vessels provide greater clarity and reveal more details than regular x-ray exams.
I've had both done a few times, and no you don't have to hold your breath!!!
at 1:51 AM on May. 22, 2009