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Patient Information

What is PET?

Positron emitting isotope

A Positron Emission Tomography (PET) scan identifies both physiological and chemical changes in the body. It distinguishes organ function rather than structure by measuring metabolic activity. An isotope, called a ‘tracer’, is injected into a vein. A tracer is a natural, slightly radioactive chemical made in a cyclotron, which is then bound with glucose (a type of sugar). The amount of activity taken up by the organs tells us whether the chemical function of that organ is normal or abnormal. This, in turn, allows for the early detection of disease.

Benefits of PET

PET is a unique clinical tool in that it may show changes before CT or MRI imaging does. It shows all organ systems of the body in one image and may prevent the need for more invasive tests.

  1. Oncology.
    As PET is extremely sensitive, it is able to differentiate most cancerous tissue from benign tumours and scar tissue. It can accurately detect and monitor the spread of malignant tumours and monitor tumour response to treatment. This is very important in assisting the referring doctor to determine the appropriate course of treatment. It also shows the physical size and structure of organs and bones.

    Currently, PET is mainly used for the detection of lung, colon, ovarian, cervical, oesophageal, gastric and breast cancer, malignant melanomas, head and neck tumours, lymphomas, certain bone cancers, secondary cancers with an unknown primary site and brain tumours. It is important to know that not all tumours take up the tracer.
  2. Epilepsy.
    PET plays a significant role in the diagnosis of epileptic patients. It can help identify the brain region causing the seizures which can assist in determining the best treatment for the patient. This may be beneficial for the patient as they may not require a more invasive procedure, such as depth electrode recordings
  3. Cardiac Viability.
    PET scans are used for cardiac function, viability and blood perfusion. PET can identify if the heart tissue is alive (viable) It can also show, using different tracers, the delivery of blood to the heart muscle (perfusion). This assists your doctor in deciding the appropriate medications and interventional procedures required.

Is PET safe?

There are no known short or long term side effects of a PET scan. You are exposed to a small amount of radiation that is not considered to be a threat to your health. This is about the same amount as one receives when having a CT scan. Pregnant or breast-feeding women should not have a PET scan without discussing the risks with their doctor.

The cost of PET

If you have a Medicare card, the costs of the PET scan can be billed directly to Medicare. Similarly, if you have a Veteran’s Affairs Gold card or are a member of the Australian Defence Force, you will not be required to pay for your scan. Should you have a Veteran’s Affairs White card, please telephone the PET Service immediately so our staff can ensure that you scan will be covered by Veteran’s Affairs. If you have a Medicare card through a reciprocal visitors agreement with your home country, you will be required to pay for your scan up-front by cheque. Similarly, if you are a non-Australian citizen, or an overseas visitor or student, you will be required to pay for your scan up-front by cheque. The fee payable varies with the type of scan, so please contact the PET Service to find out how much the scan will cost.

How do I get a PET scan?

Medicare reimbursable PET studies can only be requested by a consultant or a specialist.

Preparation

A detailed instruction sheet will be sent to you with your appointment card and you will have an opportunity to speak with a staff member before the day of your scan should you have any questions.

Included with your appointment card and instructions will be a questionnaire about your medical history and medications. It is very important to complete this questionnaire as accurately and completely as possible and bring it with you to your scan as it assists us with the administration of the tracer and interpretation of your PET scan. Avoid any strenuous physical activities (e.g. jogging, cycling, heavy gardening) beginning the day before your scan.

Please tell staff prior to the day of your scan if you are diabetic, breast feeding, if there is a chance you are pregnant or claustrophobic or fearful of closed/small spaces. Please also telephone the PET Service if you do not have a Medicare card so alternative billing arrangements can be made.

You will need to bring to your appointment any private scans you may have, such as x-rays, CT, MRI or any other nuclear medicine scans or reports. You will need to bring your Medicare card and any medications you take for pain, anxiety or claustrophobia if you think you may need them. Should you take any of these medications, or if you receive a mild sedative during your scan, you will not be allowed to drive a motor vehicle or operate machinery for the rest of the day. If this is the case, you will need to arrange for someone to take you home. We have a limited selection of CDs that you may choose from, or alternatively you may bring your own CD, as long as it is relaxing. Please do not bring any valuable items to the PET Service.

You must not have sugary foods or drink on the day of your scan (e.g. no fruit, fruit juices, soft drinks, cereals) and you must fast for 6 hours prior to your appointment. During this time you may drink water only. Should you need to have food with your medication, you may have a cracker. Please note that if you have not fasted, your scan may be rescheduled.

Myocardial (heart) scan patients:

It is important that your blood glucose level is at a certain level, so it is continuously monitored whilst you are at the PET Service up until the time of your scan. Low blood fatty acids levels and normal blood glucose levels result in optimal heart glucose and tracer uptake. This results in a better study. We may administer either glucose loading solutions or medications to assist your body in reaching the optimal blood sugar level. The PET accredited physician will decide the appropriate course of action on the day.

Diabetics

Diabetic patients need to regulate their glucose as close to normal as possible prior to the scan because the glucose in the blood competes with the labeled glucose that will be administered. The blood glucose level needs to be less than 10 mmol/L at the time of your scan. If you take insulin it must be taken at least 4 hours prior to your scan. If your glucose levels are over 10 mmol/L, please contact the PET Service prior to coming for your scan so we can work with you and your doctor to obtain a high quality scan.

The procedure

You may expect to be at the PET Service for 3 – 4 hours, depending on the type and purpose of the scan. Upon arrival, a nurse or PET technologist will go through the questionnaire you have brought in with you and assist you in answering any questions you may need clarification on. You may use this opportunity to ask any other questions you may still have. Once you have been shown through to the preparation area, a cannula will be inserted into a vein of your arm, hand or foot for the injection of the isotope. Your glucose levels are measured utilising a finger prick and blood sugar monitoring equipment. A urinary catheter and sedation is occasionally administered should they be required.

The isotope is injected through the cannula and then you are required to remain relaxed and still, lying in a dimly lit room for 45 minutes whilst the glucose is metabolising in your body. This period is called the ‘uptake period’. You will then be asked to empty your bladder. A Technologist will then take you into the camera room, where you will be made as comfortable as possible on the camera table. You will need to relax, breathe normally and stay still. Scanning takes about 30 – 90 minutes for a whole body scan, depending on the type and purpose of the scan. Heart scans take between 20 – 30 minutes and brain scans approximately 30 minutes.

During the scan you may communicate with staff at any time. You will be allowed to play gentle music during the scan if you wish. Once the scan is completed, an accredited PET physician will view the images before you leave to ensure we don’t need any additional pictures taken. After your scan, you should drink plenty of fluids and have something to eat. If you have taken any medications for claustrophobia or anxiety, or if you have received a mild sedative, someone will need to drive you home.

Results

The results of the FDG tumour scan will be available to your referring physician within 24 hours of the examination. If your physician is not at a metropolitan teaching hospital, we will attempt to call the day of the study. Sometimes it does take until the next morning to be in touch with your physician. At a later time a copy of the PET scan report and a set of images of your scan will be sent to your physician. Your referring physician will discuss the PET scan report with you.

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