Pet/CT Scan

A PET/CT scanner is an advanced imaging machine that performs two kinds of scans – PET scans (positron emission tomography) and CT scans (computed tomography) in one appointment. Both scans create very detailed pictures of the body’s organs and tissues.

These scans can help doctors find certain medical problems before they show up on other imaging tests.

Before the scan, you’ll get tracers through a vein in your arm, through a solution you drink, or in a gas you inhale. Your body needs time to absorb the tracers, so you’ll wait about an hour before the scan begins.

How long it takes for your body to fully absorb the tracer will depend on the area of the body being scanned. While you wait, you’ll want to limit any movement, relax, and try to stay warm. If you’re undergoing a brain scan, you’ll want to avoid television, music, and reading.

Next, you’ll undergo the scan, which can last anywhere from 30 to 45 minutes. This involves lying on a narrow table attached to a PET machine, which looks like a giant letter “O.” The table glides slowly into the machine so that the scan can be conducted.

You’ll need to lie still during the scan. The technician will let you know when you need to remain still. You may be asked to hold your breath for several seconds. You’ll hear buzzing and clicking noises during the test. When all the necessary images have been recorded, you’ll slide out of the machine. The test is then complete.

Preparation for the Procedure

• You will be asked to follow the Limited Carbohydrate diet for the previous 24 hours before the date of your appointment.
• Do not eat or drink anything, except water, for 6 hours before the exam. You may drink water, as much water as you can would be helpful, until arrival.
• Routine medications may be taken, unless you have been instructed otherwise. If you are diabetic, you may take your diabetes medication no less than 4 hours prior to the exam.
• Arrive 15-30 minutes before your PET scan.
• The technologist will verify your identification and exam requested.
• You will be given a contrast screening form to complete.
• In certain situations, the doctor may order lab tests prior to contrast being given.
• Commonly, contrast is injected into a vein to better define the images throughout the body. If the radiologist believes this is helpful, a small intravenous (IV) line is placed in an arm vein. Through this line, the contrast and the isotope will be injected. The contrast will be excreted through your kidneys.

During the Exam

• The duration of the exam will vary, but the average is about 2 hours.
• The technologist will position you on the exam table, and give you instructions to remain still or to hold your breath.
• You will have the opportunity to ask the technologists questions. 

After the Procedure

• You should drink about 5 glasses of water.
• Nursing mothers should wait for 24 hours before resuming breast-feeding.
• If you feel any symptoms such as nasal congestion, itchy eyes, hives, rashes, sneezing, restlessness, tremors, pain, nausea, vomiting, dizziness, please notify the staff immediately. The staff is prepared to handle these situations.

A PET scan creates images that reveal how tissues and organs function. It's often used to find medical problems such as:

• Cancer
• Heart problems
• Lung disease and lung nodules
• Brain disorders
• Conditions that affect the central nervous system

1)X-rays are useful for limited disorders and conditions .

2) CT scan better delineates soft tissue legion, fractures, tumours, fluid collection in the body as compared to x-ray.

3) MRI delineates nerves,blood vessels,brain lesions,spinal cord legion and soft tissue tumours better than CT scan.

4)PET scans identify sides of active inflammation ,infection and cancer.This helps in identifying all sides before starting of treatment and reassessment after completions of treatment.

You will be exposed to small amounts of radiation during a PET scan, but this carries a very low risk. The benefits of a PET scan are usually much greater than the risks.

Chemotherapy and radiation therapy do not ‘interfere’ with the performance of a PET/CT scan.  However, these therapies can certainly have an effect on the underlying disease that a PET scan is evaluating.  For example, if a patient has an initial PET scan which shows the extent of disease, they may undergo chemotherapy and/or radiation therapy and then return some time later for a repeat PET scan.  If all goes well, that follow-up PET scan will no longer show the disease, indicating that the treatment was a success.  Therefore, chemotherapy and radiation therapy can change the results of a PET scan, but not by interfering with the process of the PET scan itself.

No, a PET/CT scan is a test used to diagnose disease, not provide treatment. The results of a PET/CT scan help your physician determine their treatment decisions.

Although FDG is very similar to glucose, the amount injected is so small it will not affect your blood glucose level.

Yes.  As the patient, you have a right to have a copy of your images and written report.  At the time you complete your PET scan, you will be given a CD containing all the original data from your PET scan.

Along with other factors, caffeine can alter the distribution of sugar in your body. Anything that has this effect reduces image quality, which could ultimately affect your diagnosis and treatment.

The radiopharmaceuticals used for PET scan are absolutely safe and have no reported allergic reactions.

The CT scan done as a part of PET-CT procedure may be performed with or without contrast enhancement. If undergoing a combination PET-CT scan, the iodine-based contrast dye used for the CT component can cause side effects, including nausea, vomiting, headache, itching, flushing, and mild rash. In rare cases, a serious, all-body allergic reaction known as anaphylaxis may occur. Severe Reactions: They occur rarely and include convulsion, cardiopulmonary arrest, profound hypotension, and arrhythmias.