How It Is Done
A cardiac perfusion scan is usually done in a hospital radiology or
nuclear medicine department, a doctor's office, or at an outpatient clinic. The
test is done by a doctor and technologist trained in
nuclear medicine.
Resting scan
For resting scans, in which you do not exercise, you will be
asked to remove your clothing above the waist, and you will be given a hospital
gown to wear. Four electrodes will be attached to your chest to keep track of
your heartbeats.
For a resting scan, the injection site on your arm will be
cleaned and an elastic band will be placed around your upper arm. Then a small
amount of the radioactive tracer is injected, usually into a vein on the inside
of your elbow.
You will lie on your back on a table with a large camera
positioned above your chest. The camera records the tracer's signals as it
moves through your blood. The camera does not produce any radiation, so you are
not exposed to any additional radiation while the scan is being done.
You will be asked to remain very still during each scan, which
takes 5 to 10 minutes. The camera will move to take more pictures at different
angles. Several scans will be taken.
The entire test takes 30 to 40 minutes, after which you can
resume your normal activities.
Stress scan using medicine
The stress scan is done in two parts. In many hospitals, the
first images are taken while the person is at rest. Then a second set of images
is taken immediately after the person is given a medicine such as adenosine,
which makes the heart respond like it would to exercise. A stress test with
medicine is usually used when a person cannot exercise for some reason.
For this test, you will be asked to sit or lie on the examining
table and you will be given a routine electrocardiogram (EKG or ECG), which
takes about 5 to 10 minutes.
Then the medicine is injected into your arm. You may get a
headache and feel dizzy, flushed, and nauseated from the medicine, but these
symptoms usually do not last long. Additional EKGs and blood pressure
measurements are often taken. After the medicine takes effect (about 4
minutes), a small amount of radioactive tracer is injected. You will lie down
on a table for a set of scans. The camera records the tracer's signals as it
moves through your blood. The camera does not produce any radiation, so you are
not exposed to any additional radiation while the scan is being done.
Sometimes more pictures are taken after you rest for 2 to 4
hours. You may resume your normal diet and activities after the final set of
scans.
Stress scan using exercise
For stress scans using exercise, your heart rate will be checked
with an
electrocardiogram (EKG or ECG). Because EKG electrodes
need to be attached to the chest to check the heart, men are usually
bare-chested and women usually wear a bra, gown, or loose shirt. For more
information, see the medical test
Electrocardiogram.
The exercise stress scan is done in two parts. First a set of
resting images is taken, then a set of stress images is taken immediately after
exercise. In many hospitals, first resting pictures are taken using one type of
tracer. More pictures are taken using a different tracer after your heart has
been stressed by exercise.
In this stress test, you exercise on a treadmill or stationary
bike. Your heart rate will be checked during the test with standard
electrocardiography. Your blood pressure is checked using a blood pressure cuff
placed on your arm. For more information, see the medical tests
Exercise Electrocardiogram and
Electrocardiogram.
You will begin by walking or pedalling slowly and easily. Every
few minutes, the speed or incline of the treadmill or resistance of the bike
may be increased. You will exercise until you need to stop or until you reach a
suitable heart rate. At that point, a different tracer medicine is injected.
You will probably continue to exercise for an additional 30 to 60 seconds to
circulate the radioactive tracer.
You will then lie down on a table for scanning. Each scan takes 5
to 10 minutes. The camera does not produce any radiation, so you are not
exposed to any additional radiation while the scan is being done.
Sometimes more pictures are taken after you rest for 30 minutes
to 4 hours. You may usually resume your normal diet and activities after the
final set of scans.
In some hospitals, a second injection of radioactive tracer is
repeated several hours after exercise and before the final image. You may be
asked to return 24 hours after the test to have another set of pictures
taken.