Magnetic resonance imaging, Computed Axial Tomography (CT) or Positron Emission Tomography (PET) are three neuroimaging tests that allow us to obtain 3D brain images and high resolution. 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 diagnostic testing 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.
Here are the most significant differences between them:
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 powerful than Earth's. This magnetic field is combined with radio pulses to detect the magnetic characteristics of the body's hydrogen atoms, and thus be able to send the computer the information necessary to reproduce the brain image.
Provides comprehensive information of soft tissues. It is one of the most used techniques in research since it allows to obtain high-resolution images, with detail of up to 0.4 millimeters, in the case for example, of resonance of 3 Teslas.
It is harmless, does not produce ionizing radiation. Therefore, and 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 still during the entire acquisition.
It is a very noisy test. The sound comes from the vibration of the gradient coils, produced by the alternative passage of the current needed to scan.
It works with an x-ray beam. The scanner allows obtaining multiple images, taken from different angles, from the absorption made by the different tissues to X-rays.
It offers bone, soft tissue, and air images. Its resolution in soft tissues is lower than that of magnetic resonance.
It emits small ionizing radiation. The risk of developing cancer due to radiation is negligible. However, it is not recommended to repeat the test excessively and its use is only prescribed in children when it is strictly necessary. Nor is it recommended for pregnant women, because of the risk that it may affect the foetus.
Some tests can be done in just 10 minutes. The person inside the machine must also be still during the entire acquisition. It is suggested to know the CT scan price in Delhi first, before having a CT scan.
It works with a radioactive tracer that is administered intravenously before testing. To take the images, the PET machine also incorporates a CT scan or an MRI.
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, the consumption of glucose in the brain, which indicates the activity of different areas or to detect the characteristic amyloid protein deposits of Alzheimer's disease.
It also uses ionizing radiation. Therefore, the best CT scan in Delhi is not recommended for pregnant women.