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Calcium-Based MRI Sensor Enables More Sensitive Brain Imaging (mit.edu)

Posted by BeauHD on from the new-and-improved dept.

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.

30 comments

  1. What about the appendix? by Anonymous Coward · · Score: 0

    Radiologists can't even find a chronically inflammed appendix the size of a cucumber on MRI scans, why don't they work on that first?

    1. Re:What about the appendix? by Anonymous Coward · · Score: 0

      Well, MRI is the wrong tool for that job. No electrical activity in the appendix.

    2. Re:What about the appendix? by Anonymous Coward · · Score: 0

      Um, what? MRI has nothing at all to do with electrical activity!
      And how does the appendix achieve peristalsis ??

      "the appendix is innervated by the superior mesenteric plexus"

      https://www.kenhub.com/en/library/anatomy/cecum-and-vermiform-appendix

  2. The Blood-Brain Barrier by methano · · Score: 4, Informative

    It's called a barrier for a reason. It's hard to get a lot of little molecules past the blood-brain barrier and, although they're called "nano", these nanoparticles are huge by comparison.

    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.

    1. Re:The Blood-Brain Barrier by mikael · · Score: 4, 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?...)

      --
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    2. Re:The Blood-Brain Barrier by Anonymous Coward · · Score: 0

      Only retards still shoot lead.

    3. Re:The Blood-Brain Barrier by Anonymous Coward · · Score: 0

      Fuck you, abusive moderator with no sense of humor.

    4. Re: The Blood-Brain Barrier by Anonymous Coward · · Score: 0

      That's a retarded sense of humor.

  3. Unfortunately ... by fahrbot-bot · · Score: 0

    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.

    ... subjects still must think in Russian for it to work.

    --
    It must have been something you assimilated. . . .
  4. But normal people won't be allowed this by Anonymous Coward · · Score: 0

    The AMA keeps introducing advances that they won't let us have.

    1. Re:But normal people won't be allowed this by BlueStrat · · Score: 1

      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

      Strat

      --
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  5. Is this a new sensor or MRI contrast agent? by Chrisq · · Score: 4, Interesting

    Is this a new sensor, or is it a new MRI contrast agent? 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.

    1. Re:Is this a new sensor or MRI contrast agent? by ceoyoyo · · Score: 1

      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 fMRI.

  6. Won't binding to calcium lower availability? by sabbede · · Score: 1
    If calcium ions are bound to enzymes, how are they going to move into cells to do their job? I guess that if the method works the enzyme must not bind very strongly, but it still seems like it should impact functionality.

    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.

    1. Re:Won't binding to calcium lower availability? by Anonymous Coward · · Score: 0

      What is a little Alzheimer's when you can have a calcium MRI?

      BTW - the contrast agents they use today are scary, although they have refined them. They wrap gadolinium in a lipid bubble (gadolinium will severely damage you without some kind of biological insulator) and inject it into the patient, where it circulates while they measure the gadolinium metal. The problem is that not all the gadolinium is properly insulated. Out of date contrast, bad manufacturing, etc. have all led to failures. https://link.springer.com/chapter/10.1007/978-1-4939-2395-3_12

      Basically it destroys your skin and organs slowly. It is rare these days, but still possible which is why we need to move to a safer contrast material.

  7. I wish by cascadingstylesheet · · Score: 1

    `I wish they'd just invent a way to use a much, MUCH bigger MRI tube.

    1. Re:I wish by Anonymous Coward · · Score: 0

      The strength of magnet required scales quite a lot worse than linearly. Tiny tubes for mouse studies are (comparatively) incredibly easy to build. Just scaling up to human size requires liquid helium, big superconducting coils, a Faraday-lined room, etc. Scaling larger gets very, very, very expensive very fast.

    2. Re:I wish by Sporkinum · · Score: 1

      There are large bore MRI machines, like this.. http://www.hitachimed.com/prod...
      Also, open MRI machines have been around for a long time. http://www.hitachimed.com/prod...

      The open MRI machine image quality is not the best though. Much better if you can't sedate a claustrophobic
        patient though.

      --
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    3. Re:I wish by ceoyoyo · · Score: 1

      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.

    4. Re:I wish by cascadingstylesheet · · Score: 1

      There are large bore MRI machines, like this.. http://www.hitachimed.com/prod...

      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...

      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.

  8. MRI resolution? by Anonymous Coward · · Score: 0

    Hi, I'm interested in the impact of this new tech on MRI brain scan resolution. I'm trying to fix my own tumor.

  9. Great but... by Anonymous Coward · · Score: 0

    That's great and all, but I would still die because there is no way in hell you are getting me into that tiny little coffin-tube.

  10. Helvetica Scenario by Ecuador · · Score: 1

    There still needs to be rigorous testing though, since this is calcium-based, there is a higher risk for the dreaded Helvetica Scenario.

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