MRIs Getting Closer to Frog Levitation
By Kyle Hill on May 17, 2014
Tech giant GE is ushering in the new line of MRIs, and they are 140,000 times stronger than the Earth’s magnetic field. They will be like spinning 1,400 refrigerator magnets around a patient.
Nuclear Magnetic Resonance Imaging (we dropped the “nuclear” because it scares people) works by applying a moving magnetic field at the resonant frequency of the body’s hydrogen atoms. The hydrogen atoms get excited (in a physics way, not a happy way) and emit radio signals that we then detect and transform into detailed images.
The stronger magnetic field we create, the better images we can get. According to GE, their newly developed MRIs can generate 7-Teslas—five times stronger than most MRIs in hospitals and pretty close to the 8-Teslas that the magnets in the Large Hadron Collider can produce.
As you can see from the image above, better magnets mean better images, which could lead to better diagnoses. Parkinson’s disease, for example, doesn’t have any discernible markers that doctors can see in an MRI. GE claims that this might change with stronger magnets able to see finer details.
But producing that much magnetic energy isn’t easy. A 7-Tesla magnet is 11-feet long and a monstrous 80,000 pounds. It’s filled with literally miles of wire, needs to be cooled to -450 degrees Fahrenheit with 10,000 liters of liquid nitrogen over two weeks, and takes a good 40 hours to charge. It needs to be so cold because MRIs take advantage of superconductivity—when electrons flow with almost no resistance at nearly absolute-zero temperatures. These are serious machines.
When you get to 10-Teslas, it may not have a practical application for MRIs, but magnetic fields strong enough to interact on an atomic level can float a frog. So there’s that.