What is PET-CT?
= PET-CT is a noninvasive diagnostic imaging procedure
= The combined PET/CT scanner merges PET and CT images together
= CT - scans - produces a series of images showing anatomical structure and
abnormalities that do not normally show up on conventional X-rays
= In a PET scan, radioactive sugar molecules are injected into the body. Cancer cells
absorb sugar more quickly than normal cells, so they "light up" on the images created
by the PET scanner. The scan shows biologic data about the cellular activity of a tumor.
What to Expect from PET-CT study?
An integrated PET-CT scan combines the images from a positron emission tomography (PET) scan and a computed tomography (CT) scan, performed at the same time on the same machine.
Together, the two scans create a more complete (as structural as physiologic) image than either test can offer alone.
This study includes whole body imaging (usually from the base of the skull to midthighs) and is able to examine most organ systems for both primary and metastatic disease in a single procedure.
Benefit of PET in Oncology
Clinical research data has proven that PET-CT scanning is superior to conventional imaging in the diagnosis and management of various types of cancers.
Use of PET-CT can lead to a significant change in the management a patient's care.
When is PET-CT covered?
PET-CT is proved for the following indications in oncology:
= Solitary Pulmonary Nodules: Diagnosis
= Non-Small Cell Lung Cancer: Diagnosis, staging and restaging
= Esophageal Cancer: Diagnosis, staging and restaging
= Colorectal Cancer: Diagnosis, staging and restaging
= Lymphoma: Diagnosis, staging and restaging
= Melanoma: Diagnosis, staging and restaging
= Head and Neck Cancers (excluding CNS and Thyroid): Diagnosis, staging and
restaging
= Thyroid (follicular cell tumors): Restaging (when thymoglobulin is elevated)
= Breast Cancer: Staging, distant metastasis, restaging and treatment monitoring
= Cervical Cancer: Staging as adjunct to conventional imaging
PET has also been extensively studied in other cancers:
= ovarian and endometrial cancers,
= urinary bladder cancer,
= hepatocellular cancer,
= gallbladder cancer,
= sarcomas,
= gastric cancer,
= GIST,
= pancreatic cancer,
= testicular cancer,
= mesothelioma,
= renal cancer and
= unknown primary tumors.
How accurate is PET-CT?
PET-CT is considered the most advanced imaging modality for:
= identification of cancer;
= differentiation between malignant and benign disease;
= differentiation between recurrent or residual disease and therapy-induced changes;
= monitoring response to therapy.
Preparing for PET/CT Scan
Before your Appointment:
Prepare a list, which includes:
1. Names of medications you are currently taking
2. Brief medical history
3. Treatments you have had (Chemotherapy, Radiation Therapy, Surgery)
Do not eat for at least 8 hours prior: We recommend that you have nothing to eat for at least 8 hours prior to your test (except water and your usual medications).
Drink water: You are encouraged to drink 3-4 glasses of water prior to arriving at Stanford.
Do not take your diabetic medication the morning of the test. You may take all other medications as usual.
Procedure for FDG imaging:
An intravenous bolus injection of a dose of recently produced 2-FDG or 3-FDG is made, usually by a vein in one of the arms.
Dosage ranges from 0,1 to 0,2 mCi per kg of body weight.
After one or two hours, the patient is placed into the PET-CT deviceA whole body scan, which usually is made from mid-thights to the top of the head, takes about 40 min.
FDG imaging protocols acquires slices with a thickness of 2 to 3 mm.
Frequently Asked Questions:
= Are there any side effects?
You will feel no side effects from the radioactive injection.
= What do I do after the test is finished?
You may go home when the study is finished and resume your regular diet and medication. You are encouraged to drink water to help clear the radioactivity from your body.
= How do I find out about my test results?
Test results will be forwarded to your physician within 2 days.
= Can I have a PET/CT scan if I am allergic to contrast dyes?
Yes
= Can I take my medication the morning of the test?
Yes, unless it is for diabetes. All diabetic medication should be brought with you to the scanner. Please also bring your home glucometer.
= What are proteins?
Meat, milk products, cheese, nuts etc.
Atkin's diet is an appropriate diet to have the day before a scan.
= What are carbohydrates?
Bread, potatoes, pasta, beans, rice, sugar, sweets.
= Can I continue to have liquid protein tube feeds?
Yes the day before, however, we would like them to be stopped at midnight.
= Can I exercise the day before?
Only routine light exercise.
= Can I have sex the night before?
Yes, as long as you would not classify it strenuous exercise.
= Can I drink alcohol the night before?
It is best not to have alcohol.
= Can I have caffeine?
It is best to only have water on the day of the test.
= Can I wear body jewelry?
It would be best to come without any body jewelry.
= How is a PET/CT scan different from a CT scan?
The PET let's us look at glucose or sugar uptake by the cells of your body. The CT scan lets us get a clear image of the organs and tissues. Therefore, the PET scan defines sugar utilization of the tissues and a CT scan defines location and size, i.e. anatomy.
= What is significance of exposure to radiation?
A standard PET scan delivers a dose of 5-10 mSv (0.5 - 1 rad) to the body
(1 mSv = 0.1 rad).
A high-quality PET/CT examination delivers an effective dose of about
25 mSv (2.5 rad).
A low-dose technique which would decrease the effective dose from the CT
portion of the examination to less than 5 msV (0.5 rad) delivers an effective dose
of about 10-15 mSv (1-1.5 rad) | 
