What is an MRI scan?
An MRI (or magnetic resonance imaging) scan is a
radiology technique that uses magnetism, radio waves, and a computer
to produce images of body structures. The MRI scanner is a tube
surrounded by a giant circular magnet. The patient is placed on
a moveable bed that is inserted into the magnet. The magnet creates
a strong magnetic field that aligns the protons of hydrogen atoms,
which are then exposed to a beam of radio waves. This spins the
various protons of the body, and they produce a faint signal
that is detected by the receiver portion of the MRI scanner.
The receiver information is processed by a computer, and an image
is produced.
The image and resolution produced by MRI is quite
detailed and can
detect tiny changes of structures within the body. For some procedures,
contrast agents, such as gadolinium, are used to increase the accuracy
of the images.
When are MRI scans used?
An MRI scan can be used as an extremely accurate
method of disease detection throughout the body. In the head,
trauma to the brain can be seen as bleeding or swelling. Other
abnormalities often found include brain aneurysms,
stroke,
tumors
of the brain, as well as tumors or inflammation of the spine.
Neurosurgeons use an MRI scan not only in defining brain anatomy
but in evaluating the integrity of the spinal cord after trauma.
It is also used when considering problems associated with the
vertebrae or intervertebral discs of the spine. An MRI scan can
evaluate the structure of the heart and
aorta, where it can detect
aneurysms or tears.
It provides valuable information on glands
and organs within the abdomen, and accurate information about
the structure of the joints, soft tissues, and bones of the body.
Often, surgery can be deferred or more accurately directed after
knowing the results of an MRI scan.