It is a nuclear medicine imaging technique which produces a three-dimensional image or map of functional processes in the body. These images are reconstructed with the aid of a CT X-ray scan which is done on the same machine by computer analysis. It helps to locate abnormal biochemistry in a patient.
The principle behind the PET Scan
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All cells use glucose for their primary functions and the faster the growth of the cells, greater will be their use of glucose. Cancer cells are known to grow fast and hence consume more glucose.
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A type of glucose called FDG, which emits particles called positrons is used as a tracer to find the cells that grow fast.
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FDG is injected into the body of a person undergoing the PET scan.
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The scan then highlights areas in a map that indicates consumption of glucose in the body.
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These areas of the map help a physician to interpret the image as higher consumption of glucose indicates presence of cancer.
Pre-Scan preparations – Do’s and Don’ts
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It is advisable to arrive 15-20 minutes before the scheduled time of scan.
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Do not eat or take fluids (except water) for 6 hours preceeding the scan.
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Wear clothes that keep you warm.
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Diabetics need to discuss with their physicians before going for the scan.
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In case of a doubt of pregnancy, discuss with your physician as a PET scan is not performed on pregnant women.
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Any medication prescribed by your physician can be continued.
The scan process
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You are advised to carry previous X-rays, PET scans, CT and MRI scan and also respective written reports.
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After you are registered for the PET scan, you will be given intravenous through your arm. Through this, a small amount of a form of glucose called the FDG will be injected into your body.
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You will have to rest for 30-60 minutes till the I.V. is completed, which is a painless procedure.
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The scan will take a total time of 1 to 1 ½ hours after which you can leave
Activity after scan
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You can perform all your routine functions after the scan, like eating, drinking, taking your prescribed medication, driving or exercising.
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Your scan report will take about a day after your PET scan is reviewed by a physician.
Safety concerns
Although PET scanning is non-invasive, it does involve exposure to ionizing radiation. Therefore patients with small children may be advised to limit proximity to them for several hours following the completion of the test.
