MRI (Magnetic Resonance Imaging)
WHAT IS MRI?
MRI is a painless, non-invasive way to take detailed pictures of
internal organs and tissues using a powerful magnet and radio waves to
produce a series of cross-sectional images of the body. MRI provides
high-quality images with a greater level of detail compared to other
imaging modalities. It gives the best soft tissue contrast and has great
benefit in imaging the brain, spine and musculoskeletal system. Using
MRI, doctors can detect many conditions in earlier stages.
CAN I HAVE AN MRI? WHAT ARE THE RISKS?
MRI examinations are very safe for most people; however, because of the
very strong magnet used, some people cannot enter the MRI machine for
their own safety. MRI should NOT be used for patients with: pacemakers,
cochlear implants, indwelling medication pumps, certain types of
cerebral aneurysm clips, metal fragments in the eyes and some metallic
hardware. For your safety, the presence of certain metallic objects must
be determined before entering the exam room and may need to be removed
(e.g., jewelry, eyeglasses, or hairpins). Inside the bore of the MRI,
the space is small so if you are claustrophobic or think you may be, you
may need pre-medication, an â€œopenâ€ MRI, or MRI may not be for you. If
you are, or may be, pregnant, please discuss this with your doctor
before booking an MRI. There is no evidence that MRI can harm a
developing fetus, but the risk must be evaluated.
Contrast may need to be injected for certain MRI exams. Please see
the â€œif contrast is used sectionâ€ for further information regarding the
use of IV contrast.
HOW DOES MRI WORK?
There is a horizontal tube called the â€œbore,â€ which runs through the
magnet from front to back. You will lie on your back and slide into the
bore on the table. Once the body part being scanned is in the center of
the magnetic field, the MRI exam begins. You may enter head first or
feet first, and may not be entirely inside the machine depending on what
type of MRI exam is being performed.
Once in the MRI scanner, the magnetic force combines with radio wave
pulses to view various tissues in the body. The power of the magnetic
field causes hydrogen atoms in the body to organize themselves in a
certain way. The radio waves bounce off these hydrogen atoms and the
computer records the signal. Different types of tissues send back
different signals. From these signals, the scanner builds single images
called slices and integrates all of this information to create 2-D
images or 3-D models. MRI imaging is extremely detailed and is often the
choice of doctors to diagnose many conditions because the exam can be
tailored to cause tissues in the body to take on different appearances
and to help find abnormalities.
PREPARATION FOR YOUR MRI EXAM
- Most MRI exams do not require any preparation. If you are having
an MRCP (a special MRI of the abdomen), you will need to fast for
four to six hours prior to the exam.
- It is suggested that you do not wear anything metallic, if
- If you are having a scan of your brain, you should not wear
make-up, as some brands contain metal.
- You may take all medications on your usual schedule, as directed
by your doctor.
- If you are claustrophobic and are taking any medication to relax
you for the MRI, please take it as directed and bring someone with
you to drive you home after the MRI.
WHEN TO ARRIVE/WHAT TO EXPECT WHEN YOU DO
You should arrive a half hour before your appointment time and report to
the Fogarty Campus registration area to register and update your
information. You will be sent to MRI where you will change your clothes
and fill out the patient screening form (and possibly a patient
questionnaire for more information about why you are having the MRI).
The MRI technologist will review your answers with you, make sure that
you are cleared to enter the machine, explain the scanning process to
you, and answer any questions you may have prior to performing the scan.
WHAT TO EXPECT DURING THE MRI EXAM
- It is noisy inside the machine, but you may listen to a CD
during the exam or use earplugs to lessen the noise.
- The technologist will position you on the table and may place
small â€œcoilsâ€ around the head, arm, leg or other areas to be studied
to help send and receive radio waves for the best quality images.
- The technologist will watch you from the room next door and will
communicate with you via intercom. You and the technologist will be
able to see each other through the windows at all times.
- At any point in time if you feel uncomfortable or need
assistance, press the call button and the technologist will assist
you right away.
- You will have to lie flat and very still for the entire exam as
movement reduces the quality of the images.
- You may be asked to hold your breath briefly as pictures are
taken during the scan.
- If Gadolinium contrast is used, you will be injected and
returned to the scanner for pictures to be taken with contrast.
- Depending on the type of machine and the area(s) of interest,
the exam may take up to one hour or longer.
IF CONTRAST IS USED
Contrast may sometimes be needed to highlight your organs and/or blood
vessels to help the radiologist to see them better. The contrast used
for MRI exams is called Gadolinium. It does not contain iodine and is
very safe. Reaction is extremely rare. Most patients will feel nothing
at all during or after the injection. The technologist will answer any
questions you may have about the use of Gadolinium prior to injection.
Our equipment is serviced regularly to ensure your safety, and our
technologists are highly skilled and extremely knowledgeable. Also, the
MRI patient screening form is filled out by each patient and will be
thoroughly reviewed with you by the technologist prior to the exam. If
there are any contraindications, the scan will not be performed.
WHAT TO EXPECT AFTER THE MRI EXAM
There are no side effects, after-effects or restrictions after the MRI
exam. You may take all medications and perform all regular activities.
WHAT ABOUT MY RESULTS
Our radiologists will read the exam within 24 hours. If your physician
requests a STAT reading, it will be provided to them via phone call
and/or fax immediately following your exam. The results will also be
available via internet as soon as the final report is dictated by the
radiologist. A copy of the final report will be forwarded to the
ordering physician and/or primary care physician who will discuss the
results with you.