MRI - Magnetic Resonance Imaging
Magnetic Resonance Imaging (MRI) is a non-invasive procedure
using magnetism and radio waves to provide detailed images of your
body and its soft tissue structures. MRI's help diagnose your
disease, monitor the progress of your treatment or help understand
other medical situations that arise.
In most cases, there is no special preparation for an MRI scan.
You can eat and drink normally on the day of the scan although it
is best to avoid large amounts of coffee or other things that might
make you restless.
Depending on what part of your body is being scanned, you might
have to wear a gown, but usually you can wear regular clothes
(without heavy metal attachments). Because of the strong magnetism,
it is very important not to bring any metal into the scan room. You
will be asked to remove your watch, keys, coins, earrings and
anything else metallic.
For the actual procedure, you lie on your back on a movable
scanning table that moves into the MRI scanner. Depending on what
type of scan is necessary, the table moves you into the machine
head or feet first. Once the body part to be scanned is in the
exact center of the magnetic field, the scan begins.
Most young people have no trouble during the procedure but some
feel claustrophobic. To make you more comfortable, the inside of
the scanner is well lit, and has a fan that gently blows fresh air.
Even though the technician is in another room during the procedure,
he or she can see you at all times and you can see through a mirror
positioned at eye level inside the machine. You can also talk to
the technician through an intercom system. If you want, you can
usually bring someone with you in the room (check with the
technician first).
Most MRI scans take between 30 and 90 minutes. Your only job is
to remain completely still because even slight movement can spoil
the images. During the scan you will hear a variety of sounds such
as humming and hammering. It may sound like the technician is
hitting the side of the scanner with a large hammer. These sounds
are normal. You may be given earplugs or stereo headphones to
muffle the noise (in most MRI centers you can even bring your own
cassette or CD). But don't be surprised if the music is drowned out
by the noise.
Other than maybe being a little uncomfortable (and loud!), an
MRI is completely painless and you should have no side effects to
worry about.
CAT (or CT) Scan
CAT stands for Computerized Axial Tomography. (sometimes
referred to as CT scans). CAT Scans combine x-rays and computers to
produce very detailed cross sectional images of your body.
Depending on what part of your body is to be scanned, you may be
given something called "contrast" to make things show up better on
the scan. The contrast is given through an IV or if you are having
an abdominal scan, you may have to drink it. It tastes really
terrible but it's important. Just make sure it's cold and that you
have a good "chaser" nearby - soda or juice.
The good thing about CT's is that they are quick but you need to
lie very still to get a good scan. After the scan is done, it can
be computer reconstructed to show three-dimensional images of the
part of your body that was scanned.
Because the machine produces X-rays, the technician is in a
separate room near the computer but can talk with you through an
intercom. You will probably be alone in the room, unless you
request that someone be with you. That person will need to wear a
lead vest as protection against the x-rays.
Bone scans
Bone scans can show abnormalities long before they show up in
x-rays, which is why your doctor probably ordered one. The
radioactive compound is given through an IV and is absorbed by your
bones as it travels through your body. You have to drink a lot of
water or juice right after the isotope is injected to clear your
body of radioactive material not absorbed by your bones.
The bone scan may take about an hour and you have to lie very
still while the camera moves back and forth. You might be asked to
change positions several times to get different images. Because no
x-rays are emitted, you can have someone stay in the treatment room
with you.
The radioactive material or tracer concentrates in areas where
there is a lot of activity, so to speak - like normal growing bone
or in bone tumors or bone infections. These areas will show up as
"hot spots" on the scan.
Ultrasound
Ultrasound scans are images of your internal organs created by
using sound waves. High frequency waves are directed at your body
and then reflected (echoed) back to a scanner that creates an image
of the area scanned.
A special gel is spread on the skin over the area to be
examined. This helps to define the area as clearly as possible by
enhancing the transmission and reception of the sound waves. The
ultrasound scanner or transducer looks like a small paint roller
that the technician moves over the area to be scanned. It is
completely painless but the gel can sometimes feel a bit cold.
There is nothing special that you have to do to prepare for an
ultrasound and there are no side effects.