Positron emission tomography (PET) tomography is a non-invasive test that creates a nuclear image of any part of the body such as the lung or the heart. To do this, a radioactive tracer also called radionuclides is injected into the blood. Once the tracer mixes with the blood, it is absorbed by the muscles and into the organ like the heart. The scan determines whether the heart is healthy or not by showing the blood flow. For example, narrowed arteries or dead cells from a previous heart attack can be diagnosed using a PET scan.
Basic operation of a PET scan
To perform a PET CT test, the following steps occur:
A tracer is injected into the bloodstream. It is an organic compound found in bodies marked with a tiny amount of radioactive material. Generally, glucose, ammonia or water is used.
Once inside the body, the tracer generates rays of gamma energy.
The beams are picked up by a detector that goes around the body, then it sends them to a computer. The system converts the signals into clear images.
The complete image is produced by assembling images of thin slices of heart. Each slice is photographed from different directions and angles to produce a holistic, 3D image.
A health professional can determine how the heart works using the image. If the muscles are strong, the tracer is perfectly absorbed. However, if the heart is no longer viable or has dead cells, the tracer is not taken up. On the PET, the absorption level of the tracer is considered as different colors or dimming of brightness.
The need for PET testing
At present, PET scanners are one of the most accurate procedures that can be used to detect:
Coronary artery disease
Low blood flow
Depending on what the analysis shows, a doctor may recommend a heart procedure such as:
percutaneous coronary intervention (PCI)
aortocoronary bypass surgery
The operations can restore correct blood flow to the heart.
The procedure for a PET scan
A pet MRI can be done in a hospital or diagnostic laboratory. It is performed 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 attached to a device using wires. These are intended to track and record the patient’s heart rate called the EKG. The ECG also indicates when the analysis should be performed.
The next step is to create a basic image of the organ. This is done without adding a tracer and takes about half an hour. Once the baseline is scanned, the tracer is injected through an intravenous line that is stuck to the person’s arm. After adding the tracer, the patient lies flat on a table which slides into the scanning device which has an appearance similar to a massive donut.
Scanning begins when the detectors pick up signals from the plotter. The data is converted into a digital image using a computer. A single image is, in reality, an accumulation of numerous photographs taken from all angles and in slices. The whole procedure can last from one to three hours. It is essential to be completely still during the whole scanning process, otherwise the images will be blurred.
Steps to Follow After PET Scanning
Because the analysis is a non-invasive process, the person can resume regular activity immediately after the end. It is recommended that you drink plenty of fluids the next day. Water allows all radioactive materials, i.e. the tracer, to be rinsed from the body. Also make an appointment with the doctor concerned to follow up on the test results.
Risks related to PET
Generally, PET is exceptionally safe for any individual. The amount of radiation to which the body is exposed is very small. As a result, the kidneys are able to remove it from the body in no more than 24 hours. The test is not recommended if the person is:
In both cases, scanning can harm the child.
The last word
Anyone who wants to know more about PET before the procedure should consult a doctor. Some questions that can help clear up any doubts are:
How is this test better than any other?
What are the steps to prepare for scanning?
Will additional tests be required after the analysis?
When can we expect the results?
by Uma Nathan