 Your
doctor has referred you for a diagnostic study known as MRI (Magnetic Resonance
Imaging). It is an efficient, comfortable procedure which gives your doctor
information to better evaluate your current condition.
MRI imaging produces detailed pictures by using a magnetic field, radio waves
and sophisticated computer processing.
MRI is now the preferred method for assessing many parts of the body, including
the brain, joints and spine.
How MR imaging works
In MRI the body is placed in the magnetic field of the MRI machine. Radio waves
are then directed to the portion of the body being studied.
The MRI computer reads the radio waves leaving the body and processes them
into digital picture form (images). The images are recorded on film to become
part of your medical record. These pictures are then analyzed by one of the
radiologists at our center and sent, along with a written report, to your physician.
Precautions
There are several circumstances under which MR imaging should not be done, and
there are precautions which must be observed in other cases. Before your examination,
you will be asked whether or not you have any of the following:
Patients with the following should NOT have an
MRI:
- Cardiac Pacemaker
- Defibrillator
- Heart Stents (The patient may not be scanned
unless the stent was placed in the patient 8 weeks prior to the day of the
MRI scan.)
Please call (406) 327-3950 and ask to speak
to a MRI Technologist if you have any of the following:
- Cerebral aneurysm clip
- Neurostimulator
- Programmable internal or external pumps
- Pregnancy
- Other metal in the body, especially in your
eyes. (Some occupations are particularly prone to this, such as metal workers
and automotive mechanics)
The MRI Technologist will ask you for the following
information:
- The model number & manufacturer of the
device placed.
- The name of the Physician who placed it.
- The name of the facility where the surgery
was done, and the date of the procedure.
Preparing for the exam
No advance preparation is required. Eat normally and take any medication as
usual, unless your doctor has given you other instructions.
What to expect
You will be asked to remove jewelry, your watch, credit cards, dentures, hearing
aids and any metal objects which could be affected by the magnetic field. In
addition, you may be asked to change into comfortable clothing that we will
provide.
In the MRI room, you will be positioned on a softly padded table which will
be moved into the MRI machine by a health care assistant or by a technologist.
Depending on the part of your body which is being studied, a small device
called a coil will be placed over or underneath you. This is not to be constricting,
and it acts as a receiver for the radio waves produced by the MRI machine.
If only a single part of your body (for example, your head, back or knee)
is being studied, the examination usually takes 30-60 minutes. You will hear
a rhythmic thumping noise and may feel a slight vibration, but there should
be no other physical sensations.
Throughout your exam, you will be able to hear and speak to your technologist.
While the space in the MRI machine is adequate for most individuals, some people
may feel uncomfortable in it. If you have problems in confined areas,
please call us in advance to talk about this.
Occasionally a patient will need a moderate sedative to be comfortable in
the MRI machine. If this is the case you will need to bring someone to drive
you home.
Your job during the examination is simply to relax and not move. The quality
of your MR study depends very much on your ability to hold still. As in a time
exposure photograph, the MR image will blur if you move.
Results
We will send a written report of your study to your doctor. As a courtesy we
can make you a CD with a copy of your scan. You and your doctor can then discuss
the results of your study and how they apply to your medical care.
Risks and complications
In most cases, MRI is completely noninvasive, meaning that there are no injections.
In some situations, however, a contrast agent is needed. This contrast is a
liquid that is given by injection during the scan. All contrast materials used
are FDA approved and considered safe. The one used for your examination is specific
to MR imaging, and it produces fewer reactions than the iodine-containing
contrast used for CT scans and kidney x-rays.
There are no known health risks associated with the magnetic field or radio
waves used in MRI. The exposure time is of short duration and the radio frequencies
are different than those suspected of possibly causing health problems.
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