t takes only a tiny magnetic field to see clear through a person’s head, a new study shows. A method called ultra-low field magnetic resonance imaging (MRI) has captured its first, blurry shots of a human brain, revealing activity as well as structure.MRI scanners image the human body by detecting how hydrogen atoms respond to magnetic fields. They typically require fields of a few tesla – about 10,000 to 100,000 times stronger than the Earth’s magnetic field. The powerful magnets necessary make scanners pricey and also dangerous for people with metal implants.
