A thallium scan is a test that uses a radioactive substance (known as
a tracer) to produce images of the heart muscle. When combined with an
exercise test, the thallium scan helps determine if areas of the heart
do not receive enough blood.
The exercise, thallium test is especially useful in diagnosing coronary
artery disease, the presence of blockages in the coronary arteries. These
are the arteries that supply oxygen to the heart muscle. Tracers, other
than thallium, can be used for this type of scan. Your CCND doctor will
decide if your situation warrants a different type of tracer.
Before The Test
IF YOU ARE NURSING OR IF YOU THINK YOU MAY BE PREGNANT, INFORM THE
CCND DOCTOR OR NUCLEAR TECH BEFORE THE EXAMINATION.
You will receive a specific
instruction sheet that pertains
to the type of tracer
your physician plans for you to have.
you have any questions, please ask your doctor, or the
nuclear tech will be
happy to assist you.
You may be asked to fast
(not eat or drink anything) for
three to four hours
or longer prior to your exam. If you
cannot fast, or are
a diabetic, ask your CCND doctor or
nurse for special instructions.
You will be instructed
not to have food or drink prior to
the test that contains
caffeine. For example, coffee, tea,
colas (even "caffeine-free"),
and chocolate foods all
contain different amounts
Be sure to notify our
office nurse or nuclear tech of all the
medicines you are taking.
Some medicines may affect the
Wear loose, comfortable
clothing that is suitable for
exercise. You should
also wear comfortable walking
shoes or tennis shoes.
Before the test, you
will be given an explanation of the
test and you will be
asked to sign a consent form. Feel
free to ask any questions
about the procedure.
During The Test
The test has two parts: the exercise imaging portion and the rest imaging
Several electrodes (small
sticky patches) will be placed
on your chest to obtain
an electrocardiogram (ECG).
This will record your
heart's electrical activity.
An intravenous (IV) line
will be started in a vein in your
arm. This will allow
injection of the radioactive tracer
Depending on the type
of exam that is ordered, you will
be exercising several
minutes on a treadmill. If you
cannot walk on a treadmill,
then a prescribed medication
will be injected over
a several minute period. In either
case, the purpose is
to increase the workload being
placed on your heart.
You will be instructed
to report any symptoms, such as
chest pain, shortness
of breath, or dizziness. Try to
exercise for as long
as you are able to, as this will
increase the accuracy
of the test.
Tell the nuclear technician
when you are almost to the
point when you can no
longer exercise. At this point, the
tracer will be injected
into the intravenous line. You will
be asked to continue
to exercise for another minute or so
after the injection.
Imaging portion: You
will then lie flat on a special table
under a scanning camera.
Several pictures of the heart
will be taken at various
angles. You should remain still
while the pictures are
being taken. This part can take up
to 20 minutes.
After this initial set
of pictures, you will be asked to
return in 2 to 4 hours
to have additional pictures taken
without repeating exercise.
These images are compared
to the images obtained
during the first part of the test.
The technician will
give you specific instructions regarding
when to return, and
what food you can eat.
After The Test
No sedation is given
during this test, therefore, you will
be able to drive home
directly after the test.
The CCND doctor conducting
the test may be able to give
you preliminary results
before you leave. However, a
usually takes several days.
In addition to being
called, a copy of your test results is
sent to your referring
This test generally provides
more information than an
exercise stress test.
This will help your doctor make an
accurate diagnosis and
develop a treatment plan that is
best for you.