The PET scan, also called positron emission computed tomography (PET), is a widely used imaging test to diagnose cancer early, check the tumor for development and whether there is metastasis. The pet scan is able to show how the body is functioning by administering a radioactive substance, called a tracer, which when absorbed by the body, emits radiation that is captured by the device and transformed into an image.
The exam does not cause pain, however it can cause discomfort if the person is claustrophobic because it is done in an enclosed equipment. Besides being very applied in oncology, the pet scan also has utility in the diagnosis of neurological diseases, such as Alzheimer's and epilepsy.
The pet scan is an expensive exam and it is often not covered by the health plan. The value of the exam is between R $ 3000 and R $ 4000, 00. In addition, the pet scan provided by SUS is only performed for the investigation, diagnosis and follow-up of lung cancer, lymphomas, colon cancer, rectal cancer and immunoproliferative diseases, such as multiple myeloma, which is a disease in which begin to proliferate and accumulate in the bone marrow. Find out what the symptoms are and how to identify multiple myeloma.
What is it for
The pet scan is a more advantageous diagnostic test than other imaging exams such as computed tomography and magnetic resonance imaging, for example. This is because it allows visualizing the problems at the cellular level through the emission of radiation, that is, it is able to verify the metabolic activity of the cells, identifying the cancer early.
Besides the application in the identification of the cancer, the pet scan can be used to:
- To detect neurological problems, such as epilepsy and Alzheimer's;
- Check for heart problems;
- Monitor the progression of cancer;
- Monitor response to therapy;
- Identify metastatic processes.
The 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 by oral administration, through liquids, or directly into the vein of a tracer, which is usually glucose labeled with a radioactive substance. Because the tracer is glucose, this test does not pose a health risk, since it is easily eliminated by the body. The tracer administration should be fasted 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 25 to 30 minutes.
The pet scan takes 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 the cells is very large, because glucose is the energy source necessary for cell differentiation. Thus, the image formed will have denser points where there is greater consumption of glucose and, consequently, greater emission of radiation, which may characterize the tumor.
After the examination it is important that the person drink plenty of water so that the tracer is eliminated more easily. In addition, there may be mild symptoms of allergy, such as redness, at the site where the tracer was injected.
The test has no contraindications, and can be performed even in people who have diabetes or kidney problems. However, pregnant women are not advised to perform this diagnostic test, since a radioactive substance that may affect the baby is used.
