How does a positron emission tomography (PET) scan of the lung, heart, or any other part of the body work? Understanding the basics
Positron emission tomography or PET is a non-invasive test that creates a nuclear image of any part of the body, such as the lung or heart. To do this, a radioactive tracer also known as radionuclides is injected into the blood. Once the marker mixes with the blood, it travels up the muscles and enters an organ such as the heart. The scan determines whether or not the heart is healthy by showing the flow of blood. For example, narrow arteries or dead cells from a previous heart attack can be diagnosed using a PET scan.
The Basic Operation of a Positron Emission Tomography
To perform a PET CT test, the following steps occur:
- A marker is injected into the bloodstream. It is an organic compound found in bodies marked with a small amount of radioactive material. Glucose, ammonia, or water are generally used.
- Once inside the body, the tracer generates rays of gamma energy.
- The rays are captured by a detector that surrounds the body and then sends them to a computer. The system converts the signals into clear images.
- The complete image is obtained by piecing together images of thin slices of the heart. Each slice is photographed from different directions and angles to produce a holistic, three-dimensional image.
A doctor can determine how the heart is working using the image. If the muscles are strong, the marker is excellently taken. On the other hand, if the heart is no longer viable or has dead cells, the marker is not recovered. On the PET scan, the absorption level of the tracer is seen as different colors or gradations of gloss.
The need for PET testing
Today, positron emission tomography scans are one of the most accurate procedures that can be used to detect:
- Coronary artery disease
- Low blood flow
- Injured tissue
- Dead tissue
Depending on what the scan shows, a doctor may recommend a cardiac procedure such as:
- percutaneous coronary intervention (PCI)
- coronary artery bypass surgery
- Operations will be able to restore proper blood flow to the heart.
The procedure of a positron emission tomography scan
A pet MRI can be done in a hospital or diagnostic lab. It is carried out by a nuclear medicine technician and a doctor using a PET machine. The first electrodes or small metal discs are placed on the patient’s legs, arms, and chest. The electrodes are then connected to a device using cables. These are meant to track and record the patient’s heart rate called an electrocardiogram. The ECG also indicates when the scan should be done.
The next step is to create a reference image of the organ. This is done without adding the marker and takes about half an hour. Once the baseline is scanned, the marker is injected through an IV line that is attached to the person’s arm. After the marker is added, the patient lies on a table that slides into the scanning device that has an appearance similar to a massive donut.
The scan begins when the detectors pick up the signals emitted by the tracker. The data is converted into a digital image by a computer. A single image is actually an accumulation of many photographs taken from all angles and in slices. The entire procedure can take between one and three hours. It is vital to be completely still during the entire scanning process, or the images will be blurry.
Steps to follow after PET scan
Because the scan is a non-invasive process, the person can return to normal activities immediately after it is finished. It is recommended to drink plenty of fluids during the next day. The water allows all the radioactive material, that is, the tracer, to be removed from the body. Also, make an appointment with the doctor in question to follow up on the test results.
Risks related to PET
In general, the PET scan is exceptionally safe for any individual. The amount of radiation the body is exposed to is very small. Therefore, the kidneys can remove it from the body in up to 24 hours. Testing is not recommended if the person:
- Pregnant
- Mother nurse
In both cases, the scan can harm the child.
The last word
Anyone who wants to know more about the PET scan before the procedure should consult a doctor. Some questions that can help clarify all doubts are:
- How is this test better than any other?
- What are the steps to take to prepare for the scan?
- Will there be a need for additional tests after the scan?
- When can the results be expected?
