This is really cool technology, as a neuroradiologist anything that helps decrease time/cost and increase availability of imaging is a big win.
It should be clarified, though, that this machine uses a very weak magnetic field compared to traditional MRI, and while they are doing neat things to improve image quality, the resolution of their images is still far, far inferior to a standard 1.5 or 3 tesla magnet. This study does not compare to traditional MRI, just shows that it is feasible to deploy in a real clinical setting and that abnormalities can be detected. It should not be assumed that this cheap and portable technology can replace standard MRI for most indications.
You can see the lower image resolution in the JAMA Neurology paper.
It's not too shabby though, especially if you've looked at older MRI images enough.
I think part of their argument, at least implicitly, is that a lot of things don't necessarily need the resolution of standard MRI to be clinically useful, especially in places like ER settings.
My skepticism about papers like this with small Ns (maybe even some larger Ns) is how well they generalize to very unselected populations. It's sort of par for the course with early-stage medical products, even quality ones, but lots of times as the Ns increase and there's less control over the patient populations they're being used on, the patients become more heterogeneous, things don't work out quite as well.
Still good to see research in this area.
I'd have to look at the paper more closely but I wonder if this can be used for functional imaging as well.
I may be MRI ignorant, but even if the Teslas are lower, if the radius is smaller (say, can only fit a head or arm or leg), does that make up for it?
I understand MRIs are largely a compromise. Organizations will buy only 1 or 2, and therefore buy one that will fit all but the most obese patients, to the imaging detriment of anyone/anything smaller. Or is that all wrong?
No. More teslas are needed for more signal to improve the signal to noise ratio. And there is a lot of noise with portable non-shielded MRI. The only way to compensate for this is by having bigger voxels (3-5mm per voxel rather than the standard 1-2mm), or repeat scans and perform averaging. The more drastic way is to do funky image reconstruction with compressed sensing or deep learning.
The wider bore does indeed come at a cost. You have more geometric distortion and a less homogenous magnetic field at the edges of the bore. Also, you will need stronger magnetic gradients to form image, causing more energy disposition (i.e. Heating the patient) and higher probability of peripheral nerve stimulation (PNS, involuntary muscle twitches due electric fields induced in the nerve caused by MR gradients).
To add to this comment, use of strong gradients also slows down scanning When you hit SAR limits. The SAR has to be brought down with pauses between scans, reducing gradient amplitudes, reduced resolution or shorter echo trains. It’s really painful.
The compromise for bore size is convenience in fitting things in it vs homogeneity of field, field strength, and cost. This is why standard bore 7T clinical imaging systems are pretty niche, but 9-12T mouse imaging systems aren't.
To get a good high resolution signal you need field homogeneity (and/or accurate mapping), high quality gradients, and good SNR. Field strength helps with the last part.
There are other trade offs too, for example imaging artifacts due to implants (or even being able to image them), susceptibility, etc. vary with main field strength.
>need field homogeneity (and/or accurate mapping), high quality gradients
It always confused me that MRI did millimeter scale imaging with radio waves that are meters long. I learned, and other's might be interested to learn, the trick is that it's the magnetic gradient that does the imaging. Each nucleus in the volume is tagged to it's place along the magnetic gradient axis by the local magnetic field strength shifting the emission frequency proportionally. That frequency shift is then inverted back to position for that axis.
By comparison for head imaging, the Synaptive folks have pretty decent images at 0.5T, and can do DTI etc. Bulkier than this unit but still small, and much better IQ.
Long shot but do you think this would be sufficient to r/o tumor in someone with a first time seizure? What about assessing for hydrocephalus in peds with a shunt?
This looks small enough that it might just be possible to keep it in an ambulance, which would be an absolute game changer for treating stroke.
Stroke treatment medication must be taken IMMEDIATELY to avoid permanent brain damage, but there is a chance that the medication will kill you depending on the type of stroke, and the only way to find out what kind of stroke it is is with MRI.
Being able to treat stroke before a patient is MRI'd in a hospital will be a massive benefit for humanity.
I basically want to say the same thing as u/lostlogin said about CT for determination of what stroke it is, but maybe add some details.
You're basically looking at ischemic vs hemorrhagic stroke. Ischemic stroke can get tPA or thrombectomy (within a 4.5hr window based on current data). We're a bit more limited with hemorrhagic stroke, but some surgeries are successful (clipping, coil embolization, etc).
From most studies, the sensitivity of noncontrast head CT ruling out a hemorrhagic stroke (most likely due to an aneurysmal hemorrhage) is around 98-99%.[1] These tests are fast, take maybe 2-3 minutes, and the entire hospital will move heaven and earth for a stroke alert.
Why is this important? Because you're essentially limited by transport to the hospital. The MRI in ambulance will save you maybe 20-30 minutes at most. It may help some, sure, but I don't think it would be as massive a benefit as you would expect.
You could argue that we should be administering tPA en route to hospital, and that can certainly be debated. I would say that the risks of tPA administration are pretty high, and should be done while in a hospital to manage any adverse effects such as hemorrhage. Maybe if we develop better safer clot busting tools we could improve morbidity after stroke.
My vote would be to increase preventative care, so that people stop having as many strokes. It would likely be more cost effective in the long run, but I'm no economist.
P.S. your fun fact for the day is that hospitals generally lose money from strokes and tPA administration. The real money is in procedures like thrombectomy! And maybe live close to a stroke center if you're at high risk (diabetes, hypertension, coaguable)
To follow up a bit more, there isn’t really any data on the time required for a mobile MRI, but we already have ambulances fitted out with ct for stroke detection operating in many cities
Off the top of my head:
Increase access to primary care
Encourage behavioral change in people that help prevent disease (stop smoking, or don't eat sugary foods, etc)
Increase treatment affordability for preventing disease
Add on cheap treatment options if patients fail the above (more aspirin, statin, metformin, etc)
It looks just a touch too big, and weighs 440lb. Another issue is power. While it can plug into a standard wall outlet, the total power used for a scan might not be convenient for the ambulance to supply. You'd likely have to design a vehicle around it to account for space/weight/power needs.
However, this could be a interesting product for field hospitals used in disaster relief. It could also be of use at medical facilities in more rural areas, where the purchase and/or use of a conventional MRI may not be feasible.
I come here just to say the same thing, it's a game changer for stroke treatment since for the ischemic stroke (most common type of stroke) every minute lost means millions of neurons loss in the brain that cannot be recovered.
Now there is a new procedure to "fish" and remove the blood clots that are blocking the blood vessels.
Anyone know the selling price for this portable MRI? I can see that it's not for any ambulance but definitely can be equipped for the special type of ambulance vehicles catering for the stroke treatment center.
Is there space in the ambulance for such a machine? Can it be operated while the ambulance is moving? If not, is it better to get the patient to the hospital quicker or wait to perform the scan?
> Using the portable MRI device, researchers from Yale found evidence of ischemic stroke, hemorrhagic stroke, subarachnoid hemorrhage, traumatic brain injury, and brain tumors in patients presenting with neurological symptoms at Yale New Haven Hospital.
Potentially a good use of this is so we can stop running CT's on children that banged their head on something. Kids do that all the time and 99.999% of the time it's nothing but hospitals run CT's to cover their butts.
This makes me happy and sad. Happy because this is some amazing technology that will have immense benefits.
Sad for a selfish reason. I spent several years working to make a portable MRI device and ultimately failed. I do wish it had worked in our lab, but am extremely happy to see it working for humanity.
I’m reminded of the work of Mary Lou Jepsen / Openwater, who have been attempting to leverage commodity consumer imaging technology and machine learning to create personal MRI-like 3D imagers orders of magnitude less expensive and more accurate.
This is all the current information I’ve been able to find on the project, looking forward to seeing how it progresses:
Her tech is very promising. They have apparently undergone initial FDA certification for device classification, so I’m also very curious to see how they progress.
My partner's sister could've potentially been saved if this existed already. They could've moved the MRI to her instead of needing to move her to the MRI, which couldn't be done. It's difficult seeing technology that could help save someone's life come out after its too late. I hope this becomes widely available and it saves lives.
I found it interesting that his parents founded Laticrete (according to Wikipedia), a well-known construction material company. He was born into a family that quite literally builds things.
"Clinicians operating in areas outside of major metropolitan areas need rapid diagnostic imaging results especially in cases of stroke, which requires immediate treatment to prevent death or poor outcomes for patients. For instance, the portable device could be used by doctors in poor countries, rural areas, or even in ambulances to differentiate between stroke symptoms caused by a brain bleed or blood clot. "
Sounds pretty neat. I wonder why this is only a brain thing, something about size constraints maybe? I have no idea how these things might work. Can they make a mini-mri for the rest of the body?
MRI has a pretty unique value proposition for the brain, as it can detect and discern things that other modalities (CT, US) simply cannot. Even a poor quality MRI (essentially what this is) provides more information within the brain than a high resolution CT. Many of the brain pathologies are also very time-sensitive. So a good place to start.
Elsewhere in the body, MRI is less useful, and isn't really a workhorse as it is with neuroimaging. (Except maybe joint imaging.) Most emergent problems are detectable via those other cheaper, faster, & less onerous technologies.
Your guess about size is also likely correct; the positioning of the antenna/coils and relation to the magnet are very important (especially with a weak magnet) and much more challenging/variable if you're thinking about the range of abdomen sizes (for example) versus head sizes.
Do MRIs have any value in replacing physical examinations (prostate, colonoscopy) with diagnostic imaging? My understanding is that assay testing is getting better, but still no replacement for the physical procedures I mentioned.
For measuring spread of disease like prostate cancer imaging can be really helpful, see: PSMA PET-CT. I could imagine a world where imaging is really cheap and agents were safer, in which case we might opt to use imaging instead of physical exams, as they would offer way earlier detection. But for now the additional radiation (not present in MR), cost, risk, time, etc makes it a no go for standard of care screening.
Imaging in general has an important role in screening for certain diseases, and in some cases is already more important than physical examination. This mainly depends on how "well" physical examinations can detect an illness, the characteristics of a particular imaging study (cost, radiation exposure, etc), and the characteristics of a disease (prevalence in a population, potential benefit of early detection/treatment). So in short, for MRI to replace physical exam and/or lab testing in screening for a particular disease, the cost needs to come down or the benefit should outweigh the cost.
Prostate cancer screening in general is no longer officially recommended by the AAFP as a rule [1], but if a patient decides to opt-in to screening, the "assay" (PSA) is preferred over a digital rectal examination, which has been shown to be increasingly useless in the detection of prostate cancer. MRI doesn't currently have a role in prostate cancer screening, but Prostate MRI has an increasingly critical role in diagnosis.
CT colonography is currently a viable option for colon cancer screening instead of colonoscopy, though colonoscopy is still considered the gold standard.
Chest CT is currently recommended to screen for lung cancer in patient's that meet certain criteria (age, smoking history).
Mammography is obviously the workhorse of screening for breast cancer, rather than physical examination. But MRI is recommended as a screening mechanism for certain patient populations with very high risk of breast cancer (e.g. certain BRCA mutations). The small population, high prevalence, and benefit of early detection combine to make this a viable option.
I think (I might be wrong) the brain might be a good target because there is not much motion. To get fast readings from an MRI you probably need the stronger magnets. MRI works not by capturing spatial variation directly like a camera, but collects a time series of aggregate magnetic field readings while a gradient field is used to create changing spatial variation. In essence, the time series gives the k-space of the image, which is then Fourier transformed into the original image. Consequently, the body must remain fairly still while this k-space time series is constructed. The heart, for instance, is notoriously hard to image.
The size of the machine tends to scale more-than-linearly with the cross-section of the thing you're scanning. Small animal MRI machines are really tiny:
You don't typically need an MRI in an ER setting except for the problem stated, differentiating between various reasons for a stroke. A CT can do the rest and is way cheaper and simpler to setup and operate.
There are other reasons an MR could be better though, for example no ionizing radiation, so you could argue you could send more patients through it than you would with an ER CT (you would only send patients you have a higher confidence of them requiring it to avoid spamming radiation).
It also relates to the patient though. Stroke patients are often not very compliant and a morality that is slow and requires a still patient is ill suited to a lot of the work an ED sees.
True enough, but MRI is not inherently too slow for this use. If the economics otherwise made sense, an acceptably fast throughput stroke protocol MR is quite doable.
It is. The requirements of the MR environment make it a lot more difficult than CT though. For example a tubed patient is harder to manage in MR than CT, and while this is done regularly it isn't as easily done as CT.
You are probably aware, but there are 5 minute protocols (Siemens call their one a “go brain”) that are pretty reasonable, and probably not far off a gold standard routine protocol 10 years ago.
That just excludes haemorrhagic stroke rather than confirms most ischaemic strokes. It allows for antiplatlets to be safely given. MRI is still needed to diagnose all but severe or very late strokes as far as I’m aware (although this is not my field. Happy to be proven wrong)
CT is often done both as a non-contrast study (to exclude hemorrhage or large established stroke) and also as a CTA and sometimes with perfusion. This data at most stroke centers is all that is needed acutely to decide whether and how to treat, and MRI is often not done until days later to evaluate final extent of the stroke.
I saw a demo of this device at RSNA last year. It is quite small, which is their goal to make it as portable as it is. But, the opening where the body parts go is also small, and at this point too small I think to fit the whole body. It would work for head and extremities I should think.
You need a lot of Tesla’s for animal work. Everything is so small that fine slices and high in-plane resolution is needed. The spinal cord on a small dog is not always easily imaged at 3T, 0.1T is going to be a problem.
GM adverted a hand held MRI years ago. Where is it?
I fear perverse economic incentives are holding the industry back. Case in point, the X-Prize funded medical tricorder. Amazing work was done by many teams, but we see no end product because the FDA over regulates (to support entrenched business interests).
I was high school age in the early 80's when MRI machines were first getting deployed and I was very interested in the technology back then. I remember reading books/articles that claimed that within a few years there would be in-vivo NMR machines in doctors offices which would replace many blood tests. I've often wondered why that future never materialized. Is there some major technical obstacle that wasn't understood then, did the economics turn out against it or is there some other reason ?
Looking at the pictures and I can't be anything but glad and hopeful. Having recently gone through (as in, last Friday) a head MRI scan, the process definitely leaves for something to be desired for.
I don't suffer from claustrophobia normally, but being stuck in that long tunnel for half an hour really did a number on me. The head coil was a bit too snug and pressed on my chin making it harder and harder to swallow and panic started to set in halfway through. If it was just my head in a device (with clear sides nonetheless!) I would've been a-okay for longer times as well, but being in that tunnel with only my soles peaking out of it, I had a very real fear of choking and/or getting stuck.
Sometimes modern medicine feels very brutal and scary and it takes a toll on my mental wellbeing. I've put off on getting my gastroscopy for a few years now because again, I don't exactly enjoy feeling like I'm choking and dying.
Anyways, this was just a tangent. Keeping my fingers crossed that I have a tumor in my pituary, would be the best thing to discover in my situation. I'll find out on Friday!
I could breathe normally during my gastroscopy. No pain though it felt strange. The MRI was a lot more taxing mentally, and I had some of the same issues as you. Best of luck.
For their purposes, "low-field" goes down to 0.25T, which is still somewhat higher than the machine linked here, but they extrapolate values of some of the parameters all the way down to 0. (And it seems like the general principles are mostly the same.)
There is some renewed interest in low field scanners. Past four decades have mainly been pushing for higher fields to improve SNR. But low field has a few advantages:
- no need for superconducting magnets. This is a big win for developing countries and portable systems.
- better geometric accuracy. While not an show stopper as it can be corrected for, but low field exhibits better geometric accuracy as you move away from isocenter, which is of extra concern with e.g. radiotherapy applications.
- more patient comfort as lower field strengths need less strong gradients thus less chance for PNS (involuntary muscle twitches due electric fields induced in the nerves)
Can ultrasound do brain scanning ... we cannot do mri of everything due to cost and hard to arrange (even ct scan I were told is much easier to arrange but I stick to the ultrasound vs mri). but we do ultrasound more frequently. If that help, that helps.
When people are hunger As cannot afford food to tell them meat can also be food may not make sense.
I posted this article. You might have noticed that I made some minor changes to the title before I posted it to HN. I believe this improved the likelihood that it would be read by others on HN a tiny bit. I encourage others to do a little creative editing of titles, but only if it improves the titles of their posts in some way.
If you're interested to learn more about how MRI works. I recently found an excellent video on the topic. It's 42 min and quite technical, but that's what I like about it.
Isn't the resolution on these governed by the magnetic field strength (like the nuclear spectrometers in chemistry?) That's why MRI machines are so big; the magnets are insane (and (edit)[involve] a bizarre material: liquid helium!)
Ummmm... they're not made of liquid helium. They use superconducting magnets which need extremely low temperatures to work, and they use liquid helium for cooling them.
No the resolution can be set at will, down from microns to centimeters (depending on the gradient system and sequence). But! The amount of signal per voxel depends on the magnetic field strength. So with tiny voxels there is hardly any signal at low field strength so you won't see anything and you will measure mostly noise.
You can get past this with more averages. So the real issue is that it is very slow to get high resolution at low field strengths. The flip side of this is that high field strength scanners get a lot more image artefacts than low strength systems.
Using sophisticated signal processing (which has been standard for ages at this point) gets you some gains, sure; but it's not magic and high field systems have better resolution.
Worth noting: A lot of the focus on advanced signal processing has been focused on scan speed, and main field strength and homogeneity is only one factor in resolution. You need high quality gradients too, the finer the resolution the more precise everything has to be set up or you are just smearing the signal around in space.
It should be clarified, though, that this machine uses a very weak magnetic field compared to traditional MRI, and while they are doing neat things to improve image quality, the resolution of their images is still far, far inferior to a standard 1.5 or 3 tesla magnet. This study does not compare to traditional MRI, just shows that it is feasible to deploy in a real clinical setting and that abnormalities can be detected. It should not be assumed that this cheap and portable technology can replace standard MRI for most indications.
That aside, I hope we get one at my hospital!