Content
The PET scan, also called positron emission computed tomography, is an imaging test widely used to diagnose cancer early, check the development of the tumor and whether there is metastasis. PET scan is able to show how the body is functioning, through the administration of a radioactive substance, called a tracer, which when absorbed by the organism, emits radiation that is captured by the equipment and transformed into an image.
The exam does not cause pain, however it can cause discomfort if the person is claustrophobic, as it is done in a closed equipment. In addition to being widely applied in oncology, PET scan is also useful in the diagnosis of neurological diseases, such as Alzheimer's and epilepsy.
PET scan is an exam available in health plans and SUS that is only performed for investigation, diagnosis and monitoring of lung cancer, lymphomas, colon cancer, rectal cancer and immunoproliferative diseases, such as multiple myeloma, which is a disease in which blood cells start to proliferate and accumulate in the bone marrow. Find out what the symptoms are and how to identify multiple myeloma.
What is it for
PET scan is a diagnostic test that is different from other imaging exams, such as computed tomography and magnetic resonance imaging, for example. This is because it allows visualizing problems at the cellular level through the emission of radiation, that is, it is able to check the metabolic activity of cells, identifying cancer early, for example.
In addition to its application in cancer identification, PET scan can be used to:
- Detect neurological problems, such as epilepsy and dementia;
- Check for heart problems;
- Monitor the evolution of cancer;
- Monitor response to therapy;
- Identify metastatic processes.
PET scan is also able to determine the diagnosis and define prognosis, that is, the chances of improvement or worsening of the patient.
How is done
The test is done with oral administration, through liquids, or directly into the vein of a tracer, which is normally glucose marked with a radioactive substance. Because the tracer is glucose, this test does not pose a health risk, as it is easily eliminated by the body. The tracer must be administered fasting for 4 to 6 hours, according to medical advice, and the PET scan is done after 1 hour, to allow time for the radioactive substance to be absorbed by the body, and lasts about 1 hour.
PET scan makes a reading of the body, capturing the emitted radiation and forming images. In the investigation of tumor processes, for example, the consumption of glucose by cells is very large, since glucose is the source of energy necessary for cell differentiation. Thus, the formed image will have denser points where there is greater consumption of glucose and, consequently, greater emission of radiation, which can characterize the tumor.
After the examination it is important that the person drinks a lot of water so that the tracer is eliminated more easily. In addition, there may be mild allergy symptoms, such as redness, at the site where the tracer was injected.
The test has no contraindications and can be performed even on people who have diabetes or kidney problems. However, pregnant or breastfeeding women are not advised to undergo this diagnostic test, as a radioactive substance that can affect the baby is used.