Magnetic Resonance Imaging (MRI):
What You Should Know
What is an MRI?
MRIs use radio waves and strong magnets instead of X-rays. Energy from the radio waves is absorbed and then released in a pattern formed by both the type of tissue and by certain diseases.
A computer translates the pattern into a detailed image of parts of the body. Not only does this produce cross-sectional slices of the body like a CT scan, it can also produce slices that are parallel with the length of the body. An injected contrast material is sometimes used, but less often than with CT scans.
How an MRI is performed
MRI scans can be uncomfortable. A patient must lie inside a tube, which is confining and may be upsetting to people with a fear of enclosed spaces. However, newer "open" MRI machines are now available.
The machine also makes buzzing and clicking noises that some could find disturbing. Facilities may provide ear plugs or headphones with music to block the noise. MRIs can require up to an hour, but most exams last between 15 and 45 minutes depending on which body part is examined and how many images are required.
What are the possible risks of an MRI?
Certain implanted items — such as pacemakers, medicine pumps, or cochlear implants — can be a health hazard during an MRI. A screening form is required to determine eligibility.