Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Whole-body magnetic resonance imaging at 0.05 Tesla

science.org

Post reply on HN
Print view View original

61–70 of 159 posts

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#61

Post by w10-1 »

With a voxel size of 2x2x8mm^3, this would do what X-rays/CT's do now, and a bit more (but likely not replace high-energy MRI's? I'm not understanding how they rival high-energy accuracy in-silico, but that's how the paper's written)

In the acute setting, faster and more ergonomic imaging could be big. E.g., in a purpose-build brain device, if first responders had a machine that tells hemorrhagic vs ischemic stroke, it would be easier to get within the tPA time window. If it included the neck, you could assess brain and spine trauma before transport (and plan immobilization accordingly).

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#62

Post by nullc »

CooCooCaCha wrote: post #59
nullc wrote: post #41

Earlier quoted context omitted.

The state of the art MRI stuff uses "compressed sensing" -- essentially image completion in some domain or another. Presumably, carefully designed to not hallucinate details or one would hope. There isn't necessarily a particularly neutral choice here: the MRI scan isn't in the pixel domain, artifacts are going to be 'weird' looking-- e.g. edges that move during the scan ringing across the whole image.

Compressed sensing is far more mathematically rigorous.

I don't think we know what's in the black box here. It could be an equivalent relatively unopinionated regularizer ("the pixel domain will be locally smooth, to the extent it has edges they're spatially contiguous") or it could be "just look up the most similar image from a library and present that instead" or anywhere in between. :)

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#64

Post by elektropionir »

It is just weird that papers like this can be published. "Deep learning signal prediction effectively eliminated EMI signals, enabling clear imaging without shielding." - this means that they have found a way to remove random noise, which if true, should be the truly revolutionary claim in this paper. If the "EMI" is not random you can just filter it so you don't need what they are doing. If it isn't random, whatever they are doing can "predict" the noise, they even use the word in that sentence. They are claiming that they can replace physical filtering of noise before it corrupts the signal (shielding) with software "removal" of noise after it has already corrupted the signal. This is simply not possible without loss of information (i.e. resolution). The images that they get from standard Fourier Transform reconstruction are still pretty noisy so on top they "enhance" the reconstruction by running it through a neural net. At that point they don't need the signal - just tell the network what you want to see. The fact that there are no validation scans using known phantoms is telling.

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#65

Post by Toutouxc »

ed312 wrote: post #51
vhcr wrote: post #46

Earlier quoted context omitted.

Where do you draw the line? RAW, HDR, photo stitching, blur removal?

This is an excellent ponit, and I don't know where to exactly draw the line ("I know it when I see it"). I personally use "auto" (probably heuristic, maybe soon-ish AI-powered) features to adjust levels, color balance etc. Using AI to add things that are _not at all present_ in the original crossed the line into digital art vs photography for me.

I draw the line where the original pixel values are still part of the input. As long as you’re manipulating something that the camera captured, it’s still photography, even if the math isn’t the same for all pixels, or is AI powered.

But IMO it’s a point worth bringing up, most people have no idea how digital photography works and how difficult it is to measure, quantify and interpret the analog signal that comes from a camera sensor to even resemble an image.

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#66

Post by parpfish »

nullc wrote: post #9
parpfish wrote: post #3

> Each protocol was designed to have a scan time of 8 minutes or less with an image resolution of approximately 2×2×8 mm³ very cool, but is it clinically useful if one edge of your voxel is 8mm?

8mm slice thickness isn't particularly at odds with what is commonly done on commercial machines, though usually there is a second transverse scan (which can't be readily fused due to patient movement). But even if it were, plenty of interesting structures are many centimeters in size, a thousand fold decrease in costs from eliminating cryogenic / high power magnets could be very useful.

the structures are many centimeters, but I assume that the sort of anomalies you'd be looking for in a clinical scan aren't going to be that large.

if you had a fracture/tumor/damage-of-some-type that's small enough to fit between those slices and you didn't get the slices lined up just right the scan would miss it, no?

Re: Whole-body magnetic resonance imaging at 0.05 Tesla

#69

Post by op00to »

elektropionir wrote: post #64

It is just weird that papers like this can be published. "Deep learning signal prediction effectively eliminated EMI signals, enabling clear imaging without shielding." - this means that they have found a way to remove random noise, which if true, should be the truly revolutionary claim in this paper. If the "EMI" is not random you can just filter it so you don't need what they are doing. If it isn't random, whatever…

It would suck if lesions or tumors look like noise.
Post reply on HN