That’s not to say there isn’t value in mobile MR, but it’s not as the article states.
These devices are tiny and inexpensive (basically EEG headbands). Nuroflux is one (https://nuroflux.com/), I forget the name of the other.
Given these units are portable, I’m curious how acquisition times and/or resolution compares to gold-standard CT.
The time-savings seem to come from having to avoid transport to diagnostic imaging, but many EDs are already equipped with CT scanners for trauma cases.
Also I’m not sure what you increased “sensitivity” would get you. Acute stroke is a clinical diagnosis, the imaging determines the type of stroke and treatment.
https://www.sciencedirect.com/science/article/abs/pii/S00353... (there's free pdf available when you search for it): "The first-line brain imaging at WH was MRI in 69 SU (56.1%), CT in 6 (4.9%), and either MRI or CT depending on delay and severity in 48 (39.0%). The first-line brain imaging at NWH was MRI in 54 SU (43.9%), CT in 16 (13.0%) and either MRI or CT in 53 (43.1%). In practice, the proportion of patients who really underwent first-line MRI was higher than 90% in 46 SU (37.4%) at WH and in 36 SU (29.3%) at NWH"
> Also I’m not sure what you increased “sensitivity” would get you. Acute stroke is a clinical diagnosis, the imaging determines the type of stroke and treatment.
In clean and easy cases sure, not all cases are like that though and MRI is very useful then; by sensitivity I mean sensitivity - https://pmc.ncbi.nlm.nih.gov/articles/PMC1859855/
> by sensitivity I mean sensitivityWell yes, it's primary modality for stroke worldwide and it's leading modality in France, just like I've said before.
> You're a little confused. You're using "sensitivity" to mean sensitivity of detecting ischemic stroke. MRI is the obvious follow-up. When available, worldwide. But it doesn't guide emergency treatment.
I would appreciate if you stopped using condescending tone. It does not guide emergency treatment decisions because in most cases it is not performed in emergency settings. When it is performed in this setting it is guiding treatment and MRI is included in stroke guidelines for cases where clinical diagnosis is not clear (and these cases are not that rare). Why is it not widely adopted? Mostly logistic reasons (which can be overcome - like they were in France) and because TOF-MRA is generally worse than CTA. It has others positives apart from higher sensitivity though, e.g. you can use FLAIR/DWI mismatch in wake-up strokes which are VERY common (obviously perfusion serves generally same purpose).
Why not take fibrinolytics before the scan, just to be on the safe side? Ambulances could be equipped with fibrinolytics, for instance.
Is it because fibrinolytics could actually be harmful, depending on the stroke type?
A CNS hemorrhage can present similarly, but giving these meds would be a death sentence in this case.
>with a change in the primary outcome to highlight the small benefit found at 30d
So does that mean "time is brain" is a bit exaggerated then, if the benefits are small?
These meds need be given within 3-6 hours of stroke onset, depending on who you ask and what heroics you want to accomplish. After the six hour mark, you’re facing the same risks of disability from an iatrogenic bleed versus little gain from therapy because hypoxic tissue is dead at that point.
However, before that window closes, there is significant benefit in doing something versus nothing in stroke. It’s great when the use of the agent results in no deficits. The same can be said when the results are only limited deficits (i.e. use of a cane) versus a wheelchair or admission to long-term care.
Dangerous in general, especially for patients with acute stroke. Thankfully the risk of an intracranial bleed is much lower for patients without a stroke (~1% IIRC), so if you get the diagnosis wrong (as there are many mimics) at least the risk isn't as high.
> So does that mean "time is brain" is a bit exaggerated then, if the benefits are small?
¯\_(ツ)_/¯ -- my impression is that the "time is brain" is emphasizing that "earlier is better," which is absolutely the case. Unfortunately, better is not always "good."
Thankfully, for massive strokes, we now have much more effective options (which are generally performed along with tPA). Unfortunately these options require highly trained subspecialists that my be practically unavailable to rural hospitals.
Edit: To add some clarity, portable MR systems are low field, so that means the scans will be lower SNR and resolution, which are much faster to acquire. I think it would also rule out diffusion scans, since those require high gradients. MR acquisitions are also much faster nowadays due to compressed sensing and deep learning reconstructions.
Even if you have an MR machine with a very low strength primary fields you'll still need to consider safety issues related to the gradients and coils.
https://www.jira-net.or.jp/vm/pdf/ct_catalog/EMI-SCANNER.pdf
And yes a CT is preferable for stroke but you can't use a CT in a room with other people. A low field MRI might be acceptable, but there is still the noise issue and obviously field safety (though this can be less when you operate at 0.1T or something).