Patient Information on PET Scan Procedures
For the patient who is referred to our department for a PET scan by the treating physician, an appointment will be made, and instructions will be given for patient conduct before and after the examination.
A PET scan is performed after an intravenous injection of a radioactively labeled tracer. The examination is not invasive, and not painful. There are several types of scans, depending on the nature of the patient’s disease. The time required to complete the examination is from one to two hours.
During the examination, the patient lies on his/her back on a bed. The bed can move, and thus allows positioning of the problematic area of the patient’s body within the PET scanner. The scanner is open on both sides, and thus the patient does not experience a problem of lack of air or stifling feeling. After the scan is completed, the patient can leave the department and return home. The stage of processing and analysis of the scans is then performed.
Questions and Answers
Q: = What side effects are there as a result of the injection of the radioactive substance?
A: = There are no side effects.
Q: = Is there any preparation required before the scan?
A: = Yes! The patient is required to fast (though s/he may drink water) for 6 hours before the scan.
Q: = What about patients who have diabetes?
A: = The patient’s blood sugar will be measured in the department before the scan, and in the event that it is found to be very high, the required dose of insulin will be injected in order to reduce the high blood sugar.
Q: = What is the difference between a CT scan and a PET scan?
A: = A CT scan gives images of the anatomy of the body, while a PET scan gives images of the physiology and metabolism of the body.
Q: = What is the risk of a PET scan?
A: = There is no risk. The radiation exposure to the patient is less than that of a CT scan.
Q: = How long does the radioactive material remain in the body?
A: = The half-lives of the radioactive materials used for PET scans vary between 2 minutes and 2 hours. The biological half-lives of the substances are also short (the materials are excreted in the urine).
Q: = What is the accuracy of a PET scan?
A: = Very high.
Q: = Are there other PET scanners in Israel?
A: = No. At present, the PET scanner at the Hadassah Hospital, Ein Kerem, is the only dedicated PET in Israel.
Q: = What is so special about a PET scanner?
A: = Since the radioactive tracers used for PET are based on biological substances which are used by many systems in the body, the technology of PET makes it possible to locate and measure metabolic processes. For example: glucose (the sugar which the body uses to generate energy) labeled with a radioisotope can demonstrate where there is high demand for glucose in the brain, in the heart muscle, or in a malignant tumor. In tumor detection, PET scans with radioactively labeled glucose are used to distinguish between malignant tumors which have high glucose uptake, and benign tumors which do not (this can sometimes save the patient a more invasive procedure such as biopsy).
Summary
PET (Positron Emission Tomography) is a particularly efficient method for identification of a number of diseases including: various types of cancer (lung cancer, colon cancer, breast cancer, melanoma, lymphoma etc.), epilepsy, Parkinson’s disease, Alzheimer’s disease, ischemic heart disease and myocardial viability.