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Whole-body magnetic resonance imaging at 0.05 Tesla

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Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#111

Post by Auracle »

thsksbd wrote: post #90
pavlov wrote: post #36

Earlier quoted context omitted.

> “A camera is supposed to take pictures of what it sees.” Feels like that’s just a matter of expectations. A phone used to be a device for voice communications. It’s right there in the Greek etymology, “phonē” for sound. But 95% of what people do today on devices called phones is something else than voice. Similarly, if people start using cameras more to produce images of things they want rather than what exists in…

Some of us want a record of what was, not a hallucination of what might have or could have been. Courts, for example. Forensic science was revolutionized by widespread adoption of photography leading to a reduction of the importance given to witnesses. Who also hallucinate what might have happened.

So when I took an 8 second exposure of the aurora on Friday and then used Capture One to process the raw to make it more vivid than it was in real life - is that a record of what was?

Don’t get me wrong, I’m not super keen on AI type stuff in cameras as a whole. The line is muddy though. A smartphone camera straight up can’t capture the moon well, or at all. If it then looks more like it did in real life after processing is that better or worse than my above example?

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#112

Post by bufferoverflow »

atoav wrote: post #29
eig wrote: post #24

A few months ago there were articles going around about how Samsung galaxy phones were upscaling images of the Moon using AI [0]. Essentially, the model was artificially adding landmarks and details based on its training set when the real image quality was too poor to make out details. Needless to say, AI upscaling as described in this article would be a nightmare for radiologists. 90% of radiology is confirming the…

This is one aspect about machine learning models I keep discussing with non-technical passengers of the AI-hype-train: They are (in their current form) unsitable for applications where correctness is absolutely critical.

As long as AI makes things better on average, it's useful. It doesn't have to be 100% correct.

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#113

Post by dendrite9 »

Auracle wrote: post #111
thsksbd wrote: post #90

Earlier quoted context omitted.

Some of us want a record of what was, not a hallucination of what might have or could have been. Courts, for example. Forensic science was revolutionized by widespread adoption of photography leading to a reduction of the importance given to witnesses. Who also hallucinate what might have happened.

So when I took an 8 second exposure of the aurora on Friday and then used Capture One to process the raw to make it more vivid than it was in real life - is that a record of what was? Don’t get me wrong, I’m not super keen on AI type stuff in cameras as a whole. The line is muddy though. A smartphone camera straight up can’t capture the moon well, or at all. If it then looks more like it did in real life after proces…

I recently took a picture of a lizard on a granite with large grains. When I zoomed in to identify the type of lizard I saw that all the grains and some leaves on a tree had been simplified with some type of swirl. I find it unlikely those swirls were artifacts of the sensor itself. My assumption is the effect is related to compression given how often it repeated but I'm not sure.

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#114

Post by nullc »

azalemeth wrote: post #92
fnordpiglet wrote: post #83

Earlier quoted context omitted.

Would it be easier to deploy devices like this to developing counties without the infrastructure to support liquid helium distribution? I imagine a much simpler device WRT exotic cooling and distribution of material requirements is a plus. Couple that with the scarcity and non-renewable nature of helium, maybe using devices like this at scale for gross MRI imagery makes sense? The AI used here as I read it is a gener…

Zero-boil-off "dry" magnets have been widely used for the last decade -- we engineered away the thousands of litres of liquid helium in exchange for bigger electricity bills and some added complexity (and arguably cost). They basically put the cryocompressor/cold head on a large heatsinked plate and use helium gas as a working fluid to cool it and through conduction the rest of the magnet. The supercon wire has a cri…

> I've seen spurious peaks in spectra from this.

Perhaps a standard bit of kit for an imaging room ought to be a receiver at the operating frequency outside of the room that can pause the sequence when a potential jammer is active, and log the event so that you could potentially make a report to the relevant authorities (perhaps encourage them to keep the transmitters off near your facility).

Pausing the sequence is also not so much of an option when contrast was just administered either, I guess.

(I suppose if the signal weren't so hot that it was saturating the ADCs there might be some opportunity to subtract it off... but that's starting to sound like another ten thousand phd-educated hours of labour mentioned up thread)

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#115

Post by nullc »

xattt wrote: post #60
sitkack wrote: post #56

Earlier quoted context omitted.

There is an opinion piece in the same issue that agrees with you. https://www.science.org/doi/10.1126/science.adp0670 > This machine costs a fraction of current clinical scanners, is safer, and needs no costly infrastructure to run (2). Although low-field machines are not capable of yielding images that are as detailed as those from high-field clinical machines, the relatively low manufacturing and operational costs…

> I don't think this machine is being billed as replacement to high-field machines. Countries where health regulation is less developed are likely to see misrepresentation where this form of MRI will be equated to full-field MRI by snake oil salesmen.

The US government bought divining rods to detect IED's in Iraq. Dumb stuff happens, but we achieve so much in spite of it.

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#116

Post by nullc »

cornholio wrote: post #23

> We conducted imaging on healthy volunteers, capturing brain, spine, abdomen, lung, musculoskeletal, and cardiac images. Deep learning signal prediction effectively eliminated EMI signals, enabling clear imaging without shielding. So essentially, the neural net was trained to what a healthy MRI looks like and would, when exposed to abnormal structures, correct them away as EMI noise leading to wrong diagnostics? I w…

I don't think that (necessarily) says what you think it says.

You can read that as saying that the DL eliminated the background noise rather than saying that the system was conditioned on images of healthy people. From that it may well have been conditioned on just an empty machine or neutral test samples.

If so, there may be a good reason to suspect that it isn't likely to create artifacts that look like or mask anatomical structures.

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#117

Post by AdamN »

thsksbd wrote: post #90
pavlov wrote: post #36

Earlier quoted context omitted.

> “A camera is supposed to take pictures of what it sees.” Feels like that’s just a matter of expectations. A phone used to be a device for voice communications. It’s right there in the Greek etymology, “phonē” for sound. But 95% of what people do today on devices called phones is something else than voice. Similarly, if people start using cameras more to produce images of things they want rather than what exists in…

Some of us want a record of what was, not a hallucination of what might have or could have been. Courts, for example. Forensic science was revolutionized by widespread adoption of photography leading to a reduction of the importance given to witnesses. Who also hallucinate what might have happened.

Pretty much all modern digital cameras are using heuristics and algorithms to construct the image you see - it's not just a sensor grid and a bitmap file and it hasn't been for a long time.

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#118

Post by hackerlight »

cornholio wrote: post #23

> We conducted imaging on healthy volunteers, capturing brain, spine, abdomen, lung, musculoskeletal, and cardiac images. Deep learning signal prediction effectively eliminated EMI signals, enabling clear imaging without shielding. So essentially, the neural net was trained to what a healthy MRI looks like and would, when exposed to abnormal structures, correct them away as EMI noise leading to wrong diagnostics? I w…

If the noise exists only on a certain frequency then the model would learn a passband filter of sorts and won't necessarily filter out abnormal structures. But they'd need to verify that.

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#119

Post by cornholio »

nullc wrote: post #116
cornholio wrote: post #23

> We conducted imaging on healthy volunteers, capturing brain, spine, abdomen, lung, musculoskeletal, and cardiac images. Deep learning signal prediction effectively eliminated EMI signals, enabling clear imaging without shielding. So essentially, the neural net was trained to what a healthy MRI looks like and would, when exposed to abnormal structures, correct them away as EMI noise leading to wrong diagnostics? I w…

I don't think that (necessarily) says what you think it says. You can read that as saying that the DL eliminated the background noise rather than saying that the system was conditioned on images of healthy people. From that it may well have been conditioned on just an empty machine or neutral test samples. If so, there may be a good reason to suspect that it isn't likely to create artifacts that look like or mask ana…

You can read it like that, but they surely didn't prove it works like that and the burden of proof is squarely on them.

Realistically, the training set is most likely MRIs of similar tissues and would be naturally biased towards healthy structures. Even the remotest possibility of a hallucination should be addressed and disproved for such an application but they make no mention of it, just "OMG magic ENHANCE button!".

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