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.
How to Prepare
When you schedule your appointment, we will inform you about any specific
preparations depending upon the specific procedure your doctor has ordered.
Please contact the Scheduling Department at 949.764-5573 if you have any
Since you will be positioned within a large, very strong magnet, you must
remove all loose metal objects. Doing so is important for your safety
as well as that of our staff, and for proper functioning of the equipment.
We offer storage lockers in which you may keep your valuables during your
examination. You may be asked to change into a gown unless you are wearing
clothing that is metal-free. You will need to complete a detailed screening
sheet, on which you will be asked whether or not you have any metal or
other devices implanted in your body that may interfere with the scan
or cause injury to you. If you have any concerns or questions about that
aspect of the procedure, please ask the technologist before you enter
the room. We also will be happy to answer your questions by telephone
at any time before your appointment.
Options exist for patients who suffer from claustrophobia or who are unable
to lie still for several minutes at a time, such as infants or children.
Because no radiation is involved, a family member or friend can remain
in the scan room with you to offer comfort and support. Anyone who enters
the scan room will need to be screened by our staff.
A second option is taking anxiety-relieving medication such as Valium,
which your physician or our radiologist can prescribe for you. If you
think you may need to be pre-medicated, please discuss the procedure and
timing when you are scheduling your appointment. Also, be aware that you
cannot drive for several hours after you take this medication, so you
will need to arrange for transportation home.
Some types of scans require fasting beforehand. You will be instructed
if fasting is necessary for your procedure.
If your physician has ordered your MRI with radiographic contrast:
- You should inform your physician if you have any allergies. If you have
been told you are allergic to contrast or have ever had a reaction to
Iodine or any form of contrast media, your doctor may prescribe medications
to reduce the risk of an allergic reaction. A Radiology nurse should contact
you. If you have not been contacted by a Radiology nurse at least 24 hours
prior to your appointment, please contact the Imaging Scheduler immediately.
- If you have diabetes, kidney problems, lupus, surgery on your kidneys or
multiple myeloma, you must have lab work that includes a BUN and Creatinine
performed within 30 days of your exam. If you are over the age of 65 you
must have lab work within 90 days of your exam. This provides us with
information regarding your current kidney function. Please call your physician
if you have not had this blood work.
- If you are currently receiving Dialysis; please schedule your dialysis
to follow your procedure with Contrast or the following day. It is imperative
you have dialysis no later than the following day after you have received
contrast for your procedure.
- We encourage you to hydrate with oral fluids at least 24 hours prior to
your study. You may have only clear liquids as well as your necessary
medications 2 hours before your exam.
Please complete, print out and bring with you the following forms to your
Side Effects/Follow-Up Care
Side effects and complications
MRI does not cause any known long-term side effects. You may experience
temporary ringing in the ears, similar to the sensation following a loud
music concert. The earplugs should minimize this. While MRI examination
has no known effects upon a fetus, please let the staff know if you may
be pregnant. In some cases, your scan may be modified or rescheduled later
during your pregnancy.
The MRI exam itself requires no follow-up care.
Locations where Hoag provides Advanced Cardiac MRI services