PET/CT Scan (Positron Emission Tomography/Computed Tomography)
Name: __________________________________ MR:_______________________________
Date: __________________________________ Time: _____________________________
If you have any questions about
these instructions or about the
PET/CT Scan please call
608-265-8731 Monday through
Friday 800AM – 400PM.
Do not eat or drink anything except
for plain water for 6 hours before
your test (this includes chewing gum
You may take your non-diabetic
medicines as long as they do not
contain sugar or glucose.
If you have been told not to take
your medicines on an empty stomach
please do not eat more than 2 or 3
soda crackers within 4-6 hours of
If you have diabetes please do not
take your diabetic medicines for 6
hours prior to your test. Ideally we
would like your glucose less than
200 for the test, so let us know ahead
of time if we need to work with your
doctor to find the safest way for you
to get ready for your test.
If you have an insulin pump please
contact us so we can discuss your
prep for your test.
If you have any problems with
claustrophobia (afraid of small
spaces) or pain, your doctor may
prescribe medicine to help you relax
and make you comfortable during
your exam. If medicine is prescribed
you must arrange for someone to
drive you home.
No strenuous exercise for 24 hours
prior to your test.
If possible, do not wear jewelry or
clothing containing metal.
If you are pregnant or breast feeding
let us know.
Please bring your MRI or CT films
with you if they were taken at a
hospital or clinic other than UW
Why do I need a PET/CT Scan?
A CT or MRI scan tells the doctor what an
organ looks like or where a tumor is. A
PET/CT scan shows how cells and organs in
your body are working. A PET/CT scan can
measure how much energy a tumor is using.
Scar tissue and tumors that have responded
to chemotherapy or radiotherapy do not use
much energy and are not seen on the
PET/CT scan. Cells and tumors that are
growing or active use a lot of energy and are
seen as a bright area on the PET/CT scan. A
PET/CT scan can help tell the difference
between these types of cells. It is often able
to find cancer that has spread to other parts
of the body.
What is a PET/CT Scan?
A PET/CT scanner is a special camera that
can take pictures of the inside of your body
by sensing a radioactive tracer. For most
studies, this tracer is a radioactive glucose
(sugar). Before your PET/CT scan, you will
be given an injection of a small amount of
radioactive glucose. Cells in the body
absorb glucose at different rates. The
PET/CT scan can measure how much
radioactive glucose is being used. This
reflects the cells’ metabolism. A PET/CT
scan may find disease before it shows up on
other tests. It can tell doctors how a disease
responds to treatment.
Our PET Scanners are PET/CT Scanners.
This means the PET and CT Scanners are
combined as one scanner. Most of the PET
Scans will use the CT with a very low
radiation setting to create a map of what
your organs look like to help the doctors
interpret your PET Scan.
When is a PET/CT scan used?
Epilepsy: to show seizure focus
(where the seizures are coming
Alzheimer’s disease: to show areas
of reduced glucose metabolism.
Parkinson’s disease: to show areas of
Brain Tumors: to see if recurrent
tumor is present.
Cancer: to show areas of increased
glucose metabolism for staging.
Heart problems: to show blood flow
What happens when I come for the test?
You will receive an injection of a
radioactive tracer. The length of time
between the injection and the scan depends
on how long it takes the tracer to get to the
part of your body being scanned. Most
often, this will be 45 minutes to an hour.
If you are having a heart study you may not
need to wait at all. During the waiting time,
after you have been injected with the
radioactive tracer, you may not read, talk or
listen to music. For some exams you may
be asked to wait in a quiet dimly lit room so
as not to stimulate your brain by reading or
What is the scan like?
You will lie on a table that moves slowly
through the ring-like scanner. You must lie
very still because movement can effect the
test. You should feel normal during the test.
The CT Scan part is first and takes about 5
minutes. The PET Scan part is second and
takes about 35 minutes. The total exam time
from injection through scan can take 30
minutes to 2 hours.
How long will I be at the hospital?
Plan to spend 2-3 hours here. The length of
the actual exam varies depending on what
the doctor needs to see.
What happens after the scan?
You may leave as soon as the scan is
complete. You will be able to eat and drink
right away unless you have been told not to.
Drink a lot of fluids the day of the test to
help clear the tracer from your system.
Are there any risks in having a PET/CT
The radiation you from a PET/CT scan is
about the same as what you would receive
from a bone scan, a test often done in
Nuclear Medicine. The radioactive tracer
does not stay in your body for very long.
There is no reason to avoid being around
other people once you have left. To be extra
safe, avoid being around infants or women
who are pregnant for a couple of hours after
Your health care team may have given you this information as part of your care. If so, please use it and call if you
have any questions. If this information was not given to you as part of your care, please check with your doctor. This
is not medical advice. This is not to be used for diagnosis or treatment of any medical condition. Because each
person’s health needs are different, you should talk with your doctor or others on your health care team when using
this information. If you have an emergency, please call 911. Copyright © 8/2016 University of Wisconsin Hospitals
and Clinics Authority. All rights reserved. Produced by the Department of Nursing. HF#5599.