A Look Inside
Magnetic resonance tomography (MRT)! You feel scared by hearing the words and then, you’re imagining that you are on a padded table sliding slowly into a tunnel-like tube, from the top to the bottom. Hard time for claustrophobic people! But the technology behind is really benign and the medical benefits are enormous.
Magnetic resonance imaging (MRI) does not rely on the type of radiation used for an x-ray or computed tomography, but uses a powerful, constant magnetic field and radio frequency energy. During the MRI examination, the powerful, constant magnetic field aligns a tiny fraction of subatomic particles called protons that are present in most of the body’s tissues. Radio frequency energy is applied to cause these protons to produce signals that are picked up by a receiver within the scanner. These signals are specially characterized using the rapidly changing, local magnetic field and computer-processed in order to produce images of the body part of interest. As a matter of fact, MRI scanner creates three-dimensional images of body tissues (such as the brain, heart, spinal cord, arms and legs, blood) using a large magnet field and radio waves.
Nowhere else magnetism is closer to you than during this moment when the body is placed in a strong magnetic field forcing hydrogen atoms in the body to line up. In a certain way, it’s similar to how the needle on a compass moves when you hold it near a magnet. When radio waves are sent toward the lined-up hydrogen atoms, they bounce back, a computer records the signal and creates the image.
MRT can even transmit images in real-time from inside the pulsating heart or a woman’s belly during childbirth. At Berlin’s Charité Hospital doctors built an open MRI machine to enable cross-section images of birth hoping to better understand why some women need Caesareans. Before MRT, doctors had only x-ray endangering the unborn child or imprecise echographic pictures.
Paul Lauterbur of the University of Illinois and Sir Peter Mansfield of the University of Nottingham were awarded the 2003 Nobel Prize in Physiology or Medicine for their discoveries concerning magnetic resonance imaging. As a matter of fact, it was not really a groundbreaking discovery, but the outcome of many similar researches at different places in the world during some decades and the result of collaboration between Chemistry and Mathematics.
In vivo visualization in 3D using magnetic resonance is quite exciting and very useful. But they remain very expensive and for medical use only. That’s why you’ll have to wait certainly some years before publishing your own MRI 3D on YouTube…