A PET scan is an imaging technique that shows the actual functioning of the organs and tissues in the body. This scan uses a tracer which is nothing but a radioactive drug to scan the activity. A scan using this test can find diseases that are not seen in other imaging techniques.
How does a PET scan function?
This imaging test helps to find the changes that occur in the body at the cellular level. A tracer is administered to the patient who has to undergo the scan. FDG is a common tracer which is used by most Anderson PET scan Chennai centers and elsewhere. Once it enters the body, this tracer goes to the location in the body which consumes sugar and breaks down. That break down causes the positron to be released. The electron present in the body reacts with the positron and produces radioactive waves. A PET scanner then with the help of a computer interprets the waves into electrical signals. Dark shade represents the places where sugar consumption is more, tissues that are cancerous will appear brighter than the normal tissues on the images. Since these tests can discover biochemical changes in the body and also the extent of spread, it is commonly recommended to cancer patients. The tracers help to find how the tissues and organs are working and will accumulate in the region where the chemical activity is high and hence helps detect cancer. The PET scan shows them as bright spots on the scanner.
How is a tracer administered?
When a patient is recommended a PET scan by a doctor, before the imaging test, the patient is injected with a radiotracer. A vein on your arm or hand is found, and the drug is injected. This drug will take about an hour to get absorbed by the cells in the body. Patients will be asked to sit still, avoid walking and talking and asked to relax as it can affect the working of the drug. It is essential for the patient to relax. Once the drug is absorbed by the cells, a scan is performed. Bright areas on the scan represent chemical activity in the cells and an indication of a disease.
What disease does a PET scan show?
All diseases start from a cellular level, and hence PET scans can help catch these changes and also gives the doctor a chance of getting a view of complex systemic diseases such as
- Tumors in the brain
- Memory problems
- Cancer and the stage of the cancer
- How far cancer has spread and how large the tumor is
- Decide on the treatment process
- Check its spread to the other areas of the body
- Find how the patient is responding to the treatment
- Post-treatment of cancer, it shows if the cancer is active or not.
Advantages of a PET scan:
A PET scan has more benefits than a CT or MRI scan as it can find the biochemical changes in the body and helps to find the cause of the problem before it becomes apparent in the body. That enables the doctor to make an early diagnosis and provide a better and effective treatment for life-threatening diseases like cancer and other such illnesses. Also, the tracer administered carries minimal risk as it can be purged from the body in a short span of time.
Disadvantages of PET scan:
- Sometimes these tests can show high levels of activity in specific areas which is mistaken as cancer. Its accuracy is doubtful in the following scenarios:
- If the blood sugar levels are high, the cells absorb this rather than the radioactive sugar and may not show the desired results.
- May not detect tumors which are less than 7mm
- Tracer is not fully absorbed by tumors which are not active.
- The decay of the tracer is fast, and hence appointments for the scan cannot be delayed.
- PET scan cost in Chennai is expensive when compared to other imaging tests, and there are not many diagnostic centers that offer them. Moreover, it should be followed by CT and MRI for a better diagnosis.
To summarise, a PET scan shows how well your tissues and organs are working and helps investigate cases where cancer is confirmed. They also help in planning operations such as artery bypass or brain surgery.