[lostlogin]

The images are better that I expected. The ‘FLAIR like’ image is not particularly FLAIR like. FLAIR are nicer to look at when fat saturated (not everyone agrees with that), but that’s probably not feasible at that field strength and adding scan time would be a problem on these long sequences. Voxel sizes of 2x2x10 are pretty terrible resolution, but if the alternative is nothing, I guess that’s ok. The static field is so low, I’m impressed it works at all.

[TheJoeMan]

You know, sometimes all you need is “do I have a baseball sized tumor or not”.

[mabbo]

This is precisely what saved my father's life last year.

16 years ago he had some kind of brain cyst. Totally benign. But as a follow up, the doctor ordered yearly MRIs, much to his annoyance.

Last year those yearly routine MRIs spotted a brain tumor- before it had time to get dangerous or cause any damage to him. It was growing quickly though and was right near his eye. Quick surgery got it out.

I want to live in a world where everyone has access to that.

[lostlogin]

A tumour can be a lot smaller than 1cm and cause issues. A pituitary microadenoma is an example, and this machine would struggle to show it.

That said, I’d like a go. I suspect that with more samples (more time) you could get the resolution up.

[AnimalMuppet]

But if the answer is "yes", the next question is "do I also have pinhead-sized metastases, and if so, where?"

[car]

Those metastases get taken care of by chemo- or immunotherapy.

[littlestymaar]

Isn't this question answered by a PET scan and not MRI ?

[doctoring]

Usually not!

PET scans are limited in resolution when you get down to the sub-5 mm or so range due to scanner technology and fundamental limits of the physics of positron/electron annihilation & photon emission.

A typical MRI (i.e. alas, not what this article is describing) can usually resolve something at that size and identify characteristics like diffusion restriction or contrast enhancement which can confirm metastasis.

Also, in the brain, PET scans (at least the most common, FDG, which is based on glucose) are extremely limited in utility because of the baseline high glucose metabolism of the brain, which makes it hard to distinguish from the metabolic activity of a tumor.

[fluidcruft]

The flip-side of that is that PET is vastly multiple orders of magnitude far more sensitive than MRI. So while PET may not be able to localize as well as MRI, it can detect smaller things if the targeting of the radioisotope is good.

[lostlogin]

Maybe the state of play has changed, as we scan for this indication in MR, not PET.

Have you a link to something as my understanding is that small lesions are better found with MR?

Or is this a rule that applies to high end research work and hasn’t hit clinical practice yet? Maybe a limitation of the isotopes used clinically?

[lostlogin]

I am unsure of the exact state of play but believe that small mets (eg a few mm in size) are better seen with MRI. MR is probably easier to get than PET too.

There are usually a few radiologists lurking here and they would have better knowledge than me (I’m an MR tech).

https://appliedradiology.com/articles/diagnosing-brain-metas...

[innolitics]

That's absolutely true. We work with a lot of technical founders who are turning their research into a diagnostic medical devices. One of the first questions we always ask is: how will the information produced by your device help clinical decision making? More data is _nice_ but if it doesn't alter the course of treatment, it's pointless. Sometimes it's okay if the doctor doesn't know if the problem is A or B if the treatment for A and B is the same.

[queuebert]

Or a massive brain hemorrhage.

[fluidcruft]

That's generally been the challenge with these super low-field scanners--they can't get T2*/susceptibility that's anywhere close to useful (yet?).

[mwint]

Reading the terminology being thrown around here, where could I go to get a basic understanding of what you’ll are talking about?

It sounds like different modes of taking (or interpreting/visualizing?) an MRI.

[lostlogin]

I’ve spent a long time around scanners and re-read this book before helping students. It’s remarkable easy to lose track of the fundamentals, though maybe that’s just me.

The whole book is available for free as a download. MRI Made Easy (… Well almost). https://rads.web.unc.edu/wp-content/uploads/sites/12234/2018...

[fluidcruft]

(vastly simplified) MRI basically functions on two fundamental mechanisms--"spin echo" and "gradient echo". Spin echo signal is described by T1 and T2. Gradient echo signal is described by T1 and T2*. The difference between T2 and T2* relate to local magnetic properties of the tissue which is called "susceptibility". Blood contains iron so its presence alters T2* and this is exploited clinically. A good example of T2* imaging used clinically is susceptibility-weighted imaging (SWI).

T2* effects increase with higher MRI main field strength. From what I can tell so far these ultra low-field scanners have to rely on spin echoes.

[rasmus1610]

These are different MRI sequences that are weighted differently to produce a specific contrast that show different characteristics of the tissue that is imaged.

I really liked ‚MRI made easy‘ as an introduction to MRI physics. Just google it, it’s a free Book

[lostlogin]

How funny, you just beat my comment. A link to it.

https://rads.web.unc.edu/wp-content/uploads/sites/12234/2018...

[queuebert]

That's an interesting point. I didn't realize they had that problem. You could probably see a bleed on a T1 contrast exam, though.

[ska]

In that case, likely you found it before anyone asked for an MRI.

[an1sotropy]

I think it is amazing that they're getting decent ADC maps - diffusion imaging is fundamentally about measuring how much the image gets dimmer (due to diffusion sensitizing gradients), so it's always running up against SNR limits. This is so darn cool.

[lostlogin]

It really is.

For some reason it reminded me of the crazy project where some team used the earths field as the static field and just added gradients and the RF stuff. I can’t find the article I remember but this project looks similar and scans a capsicum rather than an apple.

https://www.researchgate.net/publication/6956005_A_practical...