Magnetic Resonance Imaging (MRI) produces images of the body’s internal
structures by passing radio waves through a powerful magnetic field. Differing
frequencies of radio waves are produced by the different body structures,
in return, and these are mapped and converted into digital images by a
computer. MRI is especially good for imaging soft tissues in the body,
including the brain, nerves, muscles and organs.
Detailed MR images allow physicians to better evaluate various parts of
the body and certain diseases that may not be assessed adequately with
other imaging methods such as x-ray, ultrasound or computed tomography
(also called CT or CAT scanning).
Cardiac MRI imaging is performed to help:
- Evaluate the structures and function of the heart, valves, major vessels,
and surrounding structures (such as the pericardium)
- Diagnose and manage a variety of cardiovascular problems (including cardiomyopathies
such as arrhythmogenic right ventricular dysplasia and hypertrophic cardiomyopathy;
as well as characterization of cardiac mass)
- Detect and evaluate the effects of coronary artery disease
- Plan a patient's treatment for cardiovascular problems and monitor
a patient's progress.
Cardiac MRI is the gold standard for accurate assessment of cardiac function
and volumes. While these represent some of the most popular indications
for cardiac MRI, other reasons for this test exist and your physician
will be able to determine whether this type of examination will provide
relevant information in your case.
What to Expect
During an MRI scan, you will lie comfortably on your back on a table that
is moved inside a large magnet. A piece of equipment called a "coil,"
which sends and receives the radio frequency waves used in this technology,
will be placed around the area being examined. During the scan, as with
all MRI exams, you will hear various noises, ranging from a buzzing to
a loud knocking. You will be given earplugs to diminish the noise.
Because an MRI exam can take images or "slices" from various
angles, several sequences or sets of images will be taken. Each sequence
will last from one to 10 minutes, and the technologist will inform you
before the scanning noise begins. The total exam time for a scan can range
from 30 to 60 minutes. You must lie very still during each sequence, in
order to produce clear, diagnostic images.
Depending on your symptoms or prior medical history you may be given an
intravenous contrast medium for your scan. The technologist will explain
this procedure to you if necessary.