How does MRI detect extent of injury?

According to WebMD…
An MRI is a test that uses powerful magnets, radio waves, and a computer to make detailed pictures inside your body.
For more info

Somebody who knows a lot more than I do can give a better answer, but here’s what I remember reading years ago: it has something to do with how quickly the body’s electrical charges return to their natural state after being disrupted by the spinning magnets.

The magnets cause the particles in the body to align in one direction rather than in their normal plus-to-minus position. And as they return to their usual state, the scan software can measure how long it takes. It happens more slowly(?) in thicker tissue—with the result that more solid areas appear darker(?) than less dense areas.

How am I doing so far? Not bad for an English major, I hope?

And then—I think—healing activity produces a denser appearance, so if there is a lot of activity in a certain area, it points to injury.

Also presumably you can see if something isn’t where it’s supposed to be or in the shape it’s supposed to be in. X-rays can show you that with bone masses, but for softer tissue you need MRI.

I’d give a moderately good confidence rating to my recall on this, but nothing like certainty.

It was thinking about the little pluses and minuses spinning around in my body that gave me a case of the giggles while trying to hold still during my first MRI. That was a long time ago, and that’s how old my information is.