What are the Differences Between a Resonance, a CT scan and a Brain PET Scan ?
Magnetic resonance, Computerized Axial Tomography (CAT) or Positron Emission Tomography (PET) are three neuroimaging tests that allow us to obtain high-resolution 3D images of the brain.
Neurologists can request them to confirm a diagnosis of Alzheimer's disease and rule out other causes that may be behind cognitive disorders such as memory loss.
When we talk about these tests, the image that comes to mind is that of a diagnostic test in which we have to be completely still, lying down and with our heads inside a donut-shaped device. Although the machine and a part of the procedure are similar, the three tests are different and offer us different information.
Below, we present the most significant differences between them:
Magnetic resonance
It works with a magnet. To get an idea of its power, a 3 Tesla magnetic resonance is equipped with a magnetic field 60,000 times more potent than that of the Earth. This magnetic field is combined with radio impulses to detect the magnetic characteristics of the body's hydrogen atoms, and thus be able to send the computer the necessary information to reproduce the brain image.
Provides comprehensive information of soft tissues. It is one of the most used techniques in MRI scan center in new Delhi since it allows to obtain high-resolution images, with the detail of up to 0.4 millimeters, in the case for example, of resonance of 3 Tesla.
It is harmless, and it does not produce ionizing radiation. Therefore, due to the magnetic field, it is only contraindicated in people who have a pacemaker or metal implants.
The test usually lasts more than 30 minutes. The person inside the machine must be immobile throughout the acquisition.
It is a very noisy test. The sound comes from the quiver of the gradient coils, produced by the alternative step of the current needed to scan.
TAC
It works with an X-ray beam. The scanner allows obtaining multiple images, taken from different angles, from the absorption that different tissues make to X-rays.
Offers bone, soft tissue and air images. Its resolution in soft tissues is lower than that of magnetic resonance.
It emits little ionizing radiation. The risk of having cancer due to pollution is negligible. However, it is not recommended to repeat the test excessively, and only its use is prescribed in children when it is strictly necessary. It is also not instructed for pregnant women, because of the risk that it may affect the fetus.
Some tests can be done in just 10 minutes. The person inside the machine must also be immobile throughout the acquisition.
Brain PET
It works with a radioactive tracer that is administered intravenously before performing the test. To take the images, the PET CT scanmachine also incorporates a CT or an MRI.
It provides information about biological processes. Thanks to the contrast substances contained in the tracer, it allows obtaining high definition images to assess aspects such as, for example, glucose consumption in the brain, which indicates the activity of different areas or detect amyloid protein deposits, characteristic of Alzheimer's disease.
It also uses ionizing radiation. Therefore, the test is also not recommended in pregnant women.
In addition to the time of exploration, it requires a time of preparation between the administration of the radioactive drug and the taking of the images.
Thanks to them, we can detect and analyze the brain alterations that precede Alzheimer's, and guide clinical trials that try to prevent these alterations to avoid the onset of the disease.
