Positron Emission Tomography definition
Positron emission tomography or better known as the PET Scan is an imaging test used to evaluate the functioning of organs and body tissues. This type of imaging utilizes a nuclear or radioactive compound called the radiotracer, to transmit a reverse current of images to a computer.
Doctors utilize the results of a PET scan to measure some physiological functions. Among them are the use of oxygen, sugar metabolism, blood flow, even inflammatory reactions.
This examination uses Radiotracer to emit gamma rays, special cameras, and a computer for recording and analyzing data. The goal is to identify all sorts of changes or irregularities in cells that are indicative of disease progression or abnormalities.
This early detection is very important for the success of treatment procedures and treatments of various types of diseases.
In some cases, the results of a PET scan are combined with the results of a CT scan to create a more accurate diagnosis and detailed information that is not produced by other imaging tests. The specific location of anatomical anomaly is easier to be detected by combining imaging tests.
Positron Emission Tomography Facts
Here are some important points about PET scanning. More details are in the main article.
- PET scans are often used to diagnose a condition or track their progress.
- Used in conjunction with a CT or MRI, it can show how the body parts work.
- PET scans are often used to investigate epilepsy, Alzheimer’s disease, cancer, and heart disease
- Scans are painless, but patients should not consume any food for at least 4 to 6 hours prior to the scan. They must drink plenty of water.
Positron Emission Tomography Function
Positron emission tomography is an effective way of examining chemical activity within the body, which helps to detect abnormalities in the area. Generally, positron emission tomography is used for people with cancer, heart disease, or brain disorders.
In cancer, cancer cells will absorb more radioactive material because the cells have a higher metabolism. As a result, cancer cells will look brighter than healthy cells. Positron emission tomography in cancer is used to see the spread of cancer, a response to treatment, and whether the cancer has been a relapse.
Examining heart organ
Positron emission tomography is used in the heart organ to detect the heart area that has decreased blood flow. By knowing the area, it can prevent further damage and determine whether the surgery can provide benefits.
Examining brain organ
In the brain organs, positron emission tomography detects areas that have the highest activity in a variety of situations, such as when speaking, counting, and so on. Positron emission tomography can also detect abnormalities, such as tumors, memory impairment, and seizures.
PET Scan indications
PET scans are performed by doctors to diagnose cancer, heart disease, and brain nerve disorders. Here is the explanation:
PET scan serves to detect the location of the cancer and see the spread of cancer in other parts of the body. Some of the cancers that can be scanned with a PET scan are:
- Brain cancer
- Head and neck cancer
- Breast cancer
- Cervical cancer
- Colorectal cancer
- Lung cancer
- Melanoma skin cancer
- Prostate cancer
- Pancreatic cancer
- Hodgkin’s lymphoma and non-Hodgkin’s lymphoma
- Thyroid cancer
- Esophageal cancer
Heart and lung diseases
Through a PET scan, doctors can see blood circulation, both from and towards the heart and lungs. That way, doctors can detect diseases caused by blood flow disorders.
Some types of heart disease and lung disease that can be diagnosed with a PET scan are:
- Heart infections
- Heart attack
- Cardiac sarcoidosis
- Congestive heart failure
- Pulmonary embolism
- Coronary heart disease
- Sarcoidosis of the lungs
In addition to detecting the disease, pet scan results can help doctors to determine the possible success of heart disease treatment, such as angioplasty and heart bypass surgery.
Nervous disorders of the brain
Doctors can use a PET scan to detect brain nerve disorders including:
- Alzheimer’s disease
- Brain tumors
- Parkinson’s disease
- Multiple sclerosis
- Huntington’s disease
Why do you need a Positron Emission Tomography (PET) Scan?
PET scans are mainly used to detect and monitor conditions, including cancers, neurological (brain) disorders, and cardiovascular (heart-related) diseases. It can detect cancer before the cancer can be detected using other imaging techniques (eg. CT and MRI scans).
In addition, the tool also allows your doctor to determine, whether, and where to spread the cancer to other parts of the body.
A PET Scan can help with surgical planning for epileptic seizures by showing which part of the brain is causing the epilepsy. It is also used to examine Alzheimer’s disease and Parkinson’s diseases, as the resulting images can show more definite areas of the brain that are not functioning normally.
Early detection of these neurological disorders will lead to more effective treatment.
How Positron Emission Tomography Works
In PET scanning, the engine detects radiation emitted by the radiotracer.
Radiotracer is made up of radioactive materials characterized by natural chemicals, such as glucose.
The radiotracer is injected into the body, where it moves into the cells that use glucose for energy.
The more energy a bunch of cells need, the more the Radiotracer will form at that location. This will appear on the image reconstructed by the computer.
Cells, or activities, will appear as “hot spots” or “cold spots.”
Bright active Area on PET scanning. They are known as “hot spots.”
Where the cell needs less energy, the area will become brighter. This is a “cold point.”
Compared to normal cells, cancer cells are very active in using glucose, so the radiotracer made with glucose will illuminate the area of cancer.
A radiologist will examine the resulting image on the computer, and report his findings to the doctor.
Examples of glucose-based radiotracer are Fluorodeoxyglucose (FDG). In the FDG, radioactive fluoride molecules are characterized by glucose to make the radiotracer. FDG is the most commonly used radiotracer today.
PET Scan Warning
Before performing a PET scan, the doctor will inject a radiotracer into the blood vessel. The drug is at risk of causing allergic reactions, although it is rare. Therefore, tell your doctor if you have a history of allergies.
Tell your doctor when you have the following conditions or diseases:
- Fear of narrow spaces (claustrophobia)
- Pregnant or breastfeeding
- Morbid obesity
- Allergy to iodine
- Uncontrolled diabetes
- Consumption of certain medications
Before PET Scan
The following are some of the preparations that patients need to make before undergoing a PET scan procedure:
- Fasting for 4–6 hours before a PET scan and drinking only plain water
- Avoid consumption of caffeinated beverages at least 24 hours before the test, especially when a PET scan is performed to diagnose heart disease
- Stopping the consumption of drugs for diabetes
- Do not do strenuous activities or exercise at least 24 hours before the examination.
- Removing all metal jewelry and body accessories
- Wear loose and comfortable clothes, or hospital robes when available.
- Consult a doctor when you need sedatives to treat claustrophobia during the examination
PET Scan Procedure
The PET scan procedure can last for 30–60 minutes, depending on the part of the body being examined. The following are the steps carried out by doctors or medical personnel in the PET scan examination:
- Give a radiotracer injection and recommend the patient to sit still for 1 hour for the drug to reach the cells of the examined part of the body
- Ask the patient to lie on a special bed, then push the patient into a PET scan device similar in shape to a CT Scan machine
- Running a PET scan machine to scan the patient’s organs in detail
- Recommend the patient to remain still during the examination so that the resulting image is clear and not blurred
- Review the scan results, whether they are appropriate and focused before the patient leaves the examination site
The PET scan procedure is painless. However, the patient may feel uncomfortable, having to lie down for a long time.
After PET Scan
After undergoing a PET scan, the patient can return home and carry out normal activities, unless the doctor gives other instructions.
Please note, although the amount of radiotracer administered is very low, the substance may still be in the body for several hours or days. To help remove the substance from the body, patients are recommended to multiply drinking water.
Patients should not come into contact for about 2−10 hours with pregnant women or children after undergoing a PET scan.
The patient may receive the results of a PET scan a few days after the examination. If the patient is found to be suffering from a health problem, the doctor will determine the treatment method that suits the patient’s condition.
Side Effects of PET Scan
Pet scan is relatively safe to do. Even so, this procedure still risks causing side effects, including:
- Pain or redness of the skin from radiotracer injections
- Recurrent claustrophobia during examination
- Allergic reaction to radiotracer
- Less accurate test results in uncontrolled diabetics
- Exposed to radiation despite the small dose