Everybody played with magnets when they were kids. Iron filings on a sheet of glass. Some engineers never stopped. Today on Engineering Works, we’ll look at how their grownup magnets help doctors figure out what’s wrong when you’re sick.
One of the hardest parts of treating people who are sick is figuring out what’s wrong with them. For centuries, doctors had no good way to find out what’s going on inside of us. X-rays are good at seeing our bones, but not so good at seeing other things.
That’s where MRI comes in. MRI, or magnetic resonance imaging, uses big magnets and powerful magnetic fields to help doctors see the softer parts of our bodies.
But how does MRI do that? It starts with atoms, those tiny particles that make up everything around us. Hydrogen atoms, to be exact. That’s important, because we’re almost all water and water is mostly hydrogen atoms. And, it just happens, hydrogen atoms are what makes MRIs work.
Here’s where it gets tricky, so pay attention. Like all other atoms, hydrogen atoms spin. Like billions of tiny tops, all spinning inside you. When the powerful magnetic field from an MRI machine hits them, they all line up and start spinning in the same direction. With me so far?
Okay. After all the atoms are lined up and spinning, the MRI operator changes things so that the magnetic field slides off the atoms, a thin layer at a time. When this happens, and the atoms stop spinning together, each one blinks out a signal that the MRI machine can record. Powerful computers process these little signals into images that look like fuzzy photographs. Medical specialists can interpret those images just like x-rays. Here’s looking at you, kid.