Calcium-Based MRI Sensor Enables More Sensitive Brain Imaging (mit.edu) 30
An anonymous reader quotes a report from MIT News: MIT neuroscientists have developed a new magnetic resonance imaging (MRI) sensor that allows them to monitor neural activity deep within the brain by tracking calcium ions. Because calcium ions are directly linked to neuronal firing -- unlike the changes in blood flow detected by other types of MRI, which provide an indirect signal -- this new type of sensing could allow researchers to link specific brain functions to their pattern of neuron activity, and to determine how distant brain regions communicate with each other during particular tasks. In tests in rats, the researchers showed that their calcium sensor can accurately detect changes in neural activity induced by chemical or electrical stimulation, deep within a part of the brain called the striatum.
The new sensor consists of two types of particles that cluster together in the presence of calcium. One is a naturally occurring calcium-binding protein called synaptotagmin, and the other is a magnetic iron oxide nanoparticle coated in a lipid that can also bind to synaptotagmin, but only when calcium is present. Calcium binding induces these particles to clump together, making them appear darker in an MRI image. High levels of calcium outside the neurons correlate with low neuron activity; when calcium concentrations drop, it means neurons in that area are firing electrical impulses. The current version of the sensor responds within a few seconds of the initial brain stimulation, but the researchers are working on speeding that up. They are also trying to modify the sensor so that it can spread throughout a larger region of the brain and pass through the blood-brain barrier, which would make it possible to deliver the particles without injecting them directly to the test site.
The new sensor consists of two types of particles that cluster together in the presence of calcium. One is a naturally occurring calcium-binding protein called synaptotagmin, and the other is a magnetic iron oxide nanoparticle coated in a lipid that can also bind to synaptotagmin, but only when calcium is present. Calcium binding induces these particles to clump together, making them appear darker in an MRI image. High levels of calcium outside the neurons correlate with low neuron activity; when calcium concentrations drop, it means neurons in that area are firing electrical impulses. The current version of the sensor responds within a few seconds of the initial brain stimulation, but the researchers are working on speeding that up. They are also trying to modify the sensor so that it can spread throughout a larger region of the brain and pass through the blood-brain barrier, which would make it possible to deliver the particles without injecting them directly to the test site.
The Blood-Brain Barrier (Score:5, Informative)
There's probably something here, it's just that the press release is a little over the top.
Scientist develop car to drive on Mars. Now they just have to figure out how to get it there.
Re:The Blood-Brain Barrier (Score:5, Interesting)
There's a small gap in the blood-brain barrier. It's designed to allow brain-side neuron receptors to measure glucose levels.
What about detecting iron in haemoglobin. With deoxygenated blood, haemoglobin is actually dia-magnetic and will repel a magnetic field
(around 5:00 https://www.youtube.com/watch?... [youtube.com])
Unfortunately ... (Score:1)
The current version of the sensor responds within a few seconds of the initial brain stimulation, but the researchers are working on speeding that up.
Re: (Score:2)
The AMA keeps introducing advances that they won't let us have.
But The Phone Company will!
As a matter of fact, it'll soon be be mandatory!
This has been in the works literally for decades. This breakthrough topples one of the final barriers. They've even gotten to somebody close to the POTUS!
https://youtu.be/s2NNZdigSXg [youtu.be]
Strat
Is this a new sensor or MRI contrast agent? (Score:5, Interesting)
Is this a new sensor, or is it a new MRI contrast agent [wikipedia.org]? The headline says it's a sensor but the description is of an MRI contrast agent. I was thinking it could be both (a new contrast agent and a sensor to detect it) but reading TFA it definitely looks like a agent.
This will make a big difference in how quickly it can be implemented. On one hand a new agent would need medical approval. On the other, once approved all hospitals could use it with their existing machines.
Re: (Score:2)
It's a contrast agent. It's also not likely that neuroscience studies are going to be using it routinely. The iron nanoparticles by themselves are very useful as a contrast agent but there are safety concerns so they aren't used much unless there's a medical benefit. Even standard MR contrast agents are becoming very difficult to use in healthy people.
Still, this contrast agent is likely to be very useful for animal research, if they can speed up the response so it offers practical benefits over standard f
Helvetica Scenario (Score:2)
There still needs to be rigorous testing though, since this is calcium-based, there is a higher risk for the dreaded Helvetica Scenario [youtube.com].
Won't binding to calcium lower availability? (Score:2)
And how are you supposed to get rid of it when you're done? Seems like you'd be leaving a lot of junk trapped on the wrong side of the blood-brain barrier.
I wish (Score:2)
Re: (Score:2)
There are large bore MRI machines, like this.. http://www.hitachimed.com/prod... [hitachimed.com]
Also, open MRI machines have been around for a long time. http://www.hitachimed.com/prod... [hitachimed.com]
The open MRI machine image quality is not the best though. Much better if you can't sedate a claustrophobic
patient though.
Re: (Score:2)
There are large bore MRI machines, like this.. http://www.hitachimed.com/prod... [hitachimed.com]
Yes, I've used one. They actually are not very "wide", as you can see from your own link.
The widest patient opening (74cm) of any 1.5T MR system
Also, open MRI machines have been around for a long time. http://www.hitachimed.com/prod... [hitachimed.com]
The open MRI machine image quality is not the best though. Much better if you can't sedate a claustrophobic patient though.
Precisely - what they have now isn't good enough. That's why I'm hoping for better.
Re: (Score:2)
You can use as big a bore as you want. I've seen demonstrations of MRI done in the Earth's magnetic field.
The tradeoff is between image quality, bore geometry, and cost. With cost usually having an exponential relationship to the other two.