this post was submitted on 23 Jan 2026
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MRI machines are crazy fascinating. They create a 3d model of ehatever limb you put in the tube by measuring in which way hydrogen atoms spin when under the influence of massive magnetic fields. Then do some math to represent that data as an image.
One of the loose ideas I remember from university was one professor talking about the progress of technology, concluding with something like “every invention is a logical step up from the previous one, built on increasingly intricate understanding of the way the world works and on more refined designs to employ our understanding. Except for MRI machines. If aliens landed tomorrow and we showed them our inventions, they’d be pleased to see how our progression accumulated, but at some point they’ll take one look at the MRI and say what the actual fuck is this.”
Another time he described MRI technology in our current time “like if the Crusaders had microwaves”.
To this day, any time an actually interesting innovation gets described, I still feel like it’s nothing compared to MRI tech. Really. It makes my head hurt just thinking about it. What the actual fuck is this.
Aaand then you put a bunch of enslaved lightning in rocks to work to hallucinate away the noise from the image.
Here’s the thing. Digital computing fits very neatly in the orderly march of technological progression. So yes the algorithms might be very advanced but advanced algorithms are just part of doing tech.
Jiggling hydrogen atoms of conscious beings and watching what happens is stratospherically more sci-fi than even the coolest signal processing tech. Like on a fundamental level.
How amazing does the average person think “A”I”” is? This is an order of magnitude more impressive than any society-melting party trick.
You can do nigh anything with electronics and software thanks to the cumulative efforts of many. Using physical constructions to achieve a goal is way more impressive to me.
Not that either is something to sniff at.
And have liquid Helium to cool the magnet coils so they become superconducting. Liquid helium is at 4 Kelvin!
Taking a cramped antique elevator with strange signs down into a basement with equipment holding mindboggling technology used to scan your body has a real cyberpunk vibe.
Or to put it into other words - unless these machines are incredibly cool, the electricity running through the magnets will start to heat up the magnets, causing their resistance to increase, causing them to heat up even further... eventually causing them to become incredibly hot if you're lucky, or explode if you're unlucky.
Now, I've never caused an MRI magnet to quench. But it's just as scary when it happens in a cryostat. :<
Before you people are scared to use a MRI now: I can not imagine that they don't have multiple safeties in place to avoid explosion. I've never worked on cryo stuff, but from regularly cooled big machines, there are always redundant measures to avoid the big boom, and where there aren't, you can identify them by the scary sign and the heavy breathing of the safety officer. And that is for internal stuff, patient/customer facing things are probably treated even more carefully
Oh yeah, sorry, didn't mean to scare people! Even if it catastrophically explodes, there's zero chance anything can happen to you. There's so much stuff between you and the magnet that even the worst case will just damage the machine.
In the event of a quench, there's no explosion. Just a venting of the (now) gaseous helium. Still don't want to be in it during, not no actual explosion.
The good news is, there's no way for these machines to not be incredibly cool.
Oh, is that ensured mechanically? That's really cool, do you have any links or similar? I always love learning about this kinda stuff!
I was making a joke about the two main meanings of cool.
MRI machines are really cool, like they're neat. I'm sure they can heat up, but their design is still pretty awesome.
They also use liquid nitrogen to help keep the liquid helium cold. Mainly because liquid helium is expensive and a finite resource. So the nitrogen is "topped up" much more frequently than the helium.
Pretty much. But more specifically the rate at which protons relax after the applied magnetic field. It can also be used for different molecules (13C, 19F, 31P, and others), but I think that's more for NMR (nuclear magnetic resonance) which is the same thing, but used to identify chemical structures, and not body scans.