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 does. To get pictures of your brain, the MRI scanner uses very strong magnet, and radio-frequency antennas to spin tiny atoms inside your body to help them send “signals” back to more antennas that will listen for those signals. The MRI scanner then send the analog wavelengths to computers to convert them to digital signals to create computerized images which will create highly detailed images of your brain.
The time it takes to make these pictures is longer than a quick snapshot, because the tiny atoms spin for a few minutes to create each set of images. The patients do not feel anything during the pictures other than the vibration from the machine.
The MRI Scanner is a very high powered magnet that creates a controlled magnetic field that the patient goes into for the exam. We live in a magnetic field on the earth which is about 0.4 to 0.5 Gauss, or a half Gauss field. There are different field strengths of MRI systems out there in the marketplace. 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 shaped like a donut, with a hole. The MRI manufacturers have created a bigger hole in the center of the magnet for the patients to go into. Some of those holes are around 70 centimeters across.
The low-field MRI scanners were traditionally 0.3 or 0.35Tesla. The MRI scanners in most hospitals are what’s called high field magnets and have a field strength around 1.5 Tesla, which means they are about 30,000 times the magnetic field that we normally live in.
Within the past six to seven years, there are now what are called ultra high field whole body MRI scanners that rank around the 3.0 Tesla range, around 60,000 times stronger than the magnetic field that we normally live in. More often than not, the 3.0 Tesla scanners give better picture quality for MRI brain studies because of the field strength and signal to noise ratio of the imaging.
You will also need to be “screened for metal and pacemakers before you go into the MRI exam room” for safety purposes.
No matter which field strength you choose to have your MRI Brain study performed on, we hope that you know more about MRI Brain scanners.