MRI is short for “magnetic resonance imaging.”
The MRI scanner does not use any X radiation or ionizing radiation like X-rays or a cat scan. To obtain images of your brain, the MRI scanner uses a very strong magnet and radio frequency antennas to spin tiny atoms inside your body to help them send “signals” to more antennas that will listen for those signals. The MRI scanner then sends the analog wavelengths to computers to convert them into digital signals to create computerized images that will create highly detailed images of your brain.
The time it takes to make these images is longer than a quick snapshot, because the tiny atoms rotate for a few minutes to create each set of images. Patients feel nothing during the images other than the vibration of the machine.
The MRI scanner is a very high-powered magnet that creates a controlled magnetic field that the patient enters for examination. We live in a magnetic field on earth that is about 0.4 to 0.5 Gauss, or half a Gaussian field. There are different field strengths of MRI systems on the market. Most open MRI scanners were low-field systems a decade ago, but now many of the higher-field systems are called open even if they are donut-shaped, with a hole. MRI manufacturers have created a larger hole in the center of the magnet for patients to enter. Some of those holes are around 70 centimeters wide.
Low-field MRI scanners were traditionally 0.3 or 0.35 Tesla. The MRI scanners in most hospitals are what are called high-field magnets and have a field strength of around 1.5 Tesla, which means they are about 30,000 times the magnetic field we normally live in. .
In the last six to seven years, there are now what are called ultra-high-field full-body MRI scanners that sit around the 3.0 Tesla range, around 60,000 times stronger than the magnetic field we normally live in. . Most of the time, 3.0 Tesla scanners provide better image quality for MRI brain studies due to the field strength and signal-to-noise ratio of the images.
You will also need to be “screened for metals and pacemakers before entering the MRI exam room” for safety reasons.
Regardless of the field strength you choose to perform your brain MRI study, we hope you know more about brain MRI scans.
