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Has your MRI clinic booked you in for a scan in the near future? Or are you just curious about how MRI scanners work? Well, you’ve come to the right place. This post has everything you need to know about the MRI scan machine! From how it works, to interesting facts you never would have guessed.

Interested? Read on and find out more!

MRI scan machine

Image courtesy of Storyblocks.

How does an MRI scan machine work?

MRI scanners are among the most powerful and accurate diagnostic tools available. They help doctors around the world to treat their patients, by accurately diagnosing their condition, and the efficacy of any treatment they’re prescribed. Not only that, but they’re one of the safest diagnostic scans available to medical science. But how exactly does an MRI scanner work?

The first clue is that MRI stands for magnetic resonance imaging. So we can establish that MRI scanners use some kind of magnetism (electromagnetism, to be precise) to see inside the body. And that’s true, although the real way that MRI scanners work is a little more complicated than that! You have to start by understanding that the human body is mostly made of water. Now, of course, if you stand close to a magnet you won’t notice any physical changes, no matter how long you’re next to it. But on a microscopic level, the water in your body actually does react.

When placed in a strong magnetic field, the hydrogen atoms of the water inside your cells starts to move. Do you remember your high school science class experiments? Like the one with the magnet and the iron filings? If you skipped class that day, when you sprinkle iron filings around a magnet they fall in a particular pattern because of the effect of the magnetism. Believe it or not, the hydrogen atoms of the water in your cells do exactly the same when they’re placed in a strong magnetic field. The change happens at different rates in different kinds of tissue. Radio waves produced by the scanner detect these changes to create a detailed image of your tissue. Sounds crazy? It’s true.

Are there different kinds of MRI scan machine?

There are a number of different kinds of MRI scanner. For starters, there are ‘closed bore’, ‘wide-bore’ and ‘open’ MRI scanners. The earliest models were of the closed bore kind. Basically, a closed bore scanner is like a big box that you slide into. Because some people find that experience claustrophobic, wide bore and open scanners were invented! Wide bore scanners have a little more room for you to fit into, normally only a few inches, but that can make a big difference. Open MRI scanners offer plenty more room, but aren’t as powerful. That’s the tradeoff that a clinic has to make between patient comfort, image quality, and scanner cost.

There are also mobile MRI scanners! These scanners are built into large lorries which can be stationed outside a clinic to offer extra scanner availability. Or, clinics can request them where they’re needed most. There are also combined PET-MRI scanners. These are some of the most modern on the market, having first been introduced in 2011. Since then, clinics haven’t adopted them all that quickly, and there are only 70 models of this MRI scan machine in use worldwide. Without going into too much detail, PET-MRI scanners offer the best of both worlds that PET scanners and MRI scanners normally offer alone. So that’s the soft tissue contrast scanning of MRI, with the quantitative data that a PET scanner can create.

When was the first MRI scan performed?

MRI scanning has a long history. It was first theorized by a physician named Raymond Damadian, who wrote in the journal Science about the idea way back in 1971. He worked on turning his theory into practice over a number of years, before in 1974 he was granted his first patent. He wasn’t working in secrecy, so his seminal paper sparked a revolution of thought which spread across the world. The very first MRI scan on a human being was performed in England in 1976, on the finger of a scientist named Andrew Maudsley. But it was Damadian himself who would perform the first ever full body scan just a year later on a fellow scientist. It took five hours to produce a simplistic, low resolution image of his midriff. Thankfully, an MRI scan machine doesn’t take that long to produce images these days.

Are MRI scans dangerous?

MRI scans are not dangerous, not in the same way as an X-ray scan, and not in any other way either! Every year, roughly 10 million patients across the world undergo MRI scans. None of them are injured in any way because of the scan. Although, that being said, there are a few ways that an MRI scan could pose a danger.

First, the fact that the magnets used in the scanner are very powerful, means that metal objects can be pulled across the room towards the scanner- and the patient inside. That’s why scan rooms in clinics like ours use only non-magnetic metals! And if you have a pacemaker, that’s what we call an absolute contraindication to you having a scan: there’s no way you’re allowed. Unless, that is, you have one of a number of modern pacemakers that are designed specifically to be MRI safe! It’s also possible to have an allergic reaction to the contrast injection, although that’s incredibly rare. And last but not least, the magnets in an MRI have to run at exceptionally cold temperatures. In fact, they run very close to absolute zero, the coldest possible temperature- around -270 degrees centigrade, or -459 fahrenheit. They’re contained securely in their housing, though, so you can’t touch them!