Ultrasound imaging of the brain

Join the discussion

• Hacker News
• Not trying to sound alarmist at all but I am wondering if ultrasounds are safe to be used like this? My understanding is it's basically a high-frequency sound wave which is probably fine for most tissue usage, however here it says it's scattering off of red blood cells. I don't know why that feels so unsettling to me.
  by trevor-e
• Every few years one of these ultrasound companies comes around and promising to revolutionize medical imaging and nothing ever comes of it. Anyone remember https://www.openwater.health? The same ideas are in a perpetual state of being reinvented and part of me thinks its just a hustle for the MIT Media Lab/Stanford Imaging grads to give them something to do.

  The tell is "super resolution", "brain computer interface" and "mixed modality" -- adding some contrast agent here, or maybe an IR light source.

  It turns out the nyquist limit, diffraction and physics are real things.

  by iamleppert
• Meta is also going at it [0], which inevitably makes me ponder some orwellian questions for the near future:

  If I bring my pet mouse to the cinema and my friend scans the movie back using his apple ifmri does the DRM still holds or will the mouses be DRM locked? Will my iris suffice for booting my computer or would I need to press accept all brainwave cookies? Can I email my local Flock representative to install a new Brain Pole in my neighborhood? I saw a bunch of dark thoughted young males around and my amazon think camera says the probability of missing packages increased.

  [0]https://ai.meta.com/blog/tribe-v2-brain-predictive-foundatio...

  by frangonf
• The imaging stuff is cool but the homepage is making me wince.

  There's a compelling argument to be made that the level of detail in "mind reading" they are gesturing at is plain unrecoverable with hemodynamics. There's an irreversible loss of dimensions that occurs the instant you start recording blood instead of spikes on the neural circuits themselves, and it's not at all clear that what a VC reading the words "telepathy" is imagining even survives that transformation.

  What you have is food delivery data for a neighborhood, this can tell you a surprising amount, including when they might throw a party. What it can't tell you, however, is who wore the best outfit and what was talked about over dinner. The information simply does not survive across the interface.

  There is a spectacular canyon between "informed interpretation" and "mind reading"

  by Unearned5161
• re: imaging red blood cells

  The super-resolution trick as they’ve done it is highly reliant on the sparseness of the bubbles. If you imagine a point or a very sparse set of points at low resolution, you can fit for the locations of those points even though you don’t see them clearly. This is a common technique in radio astronomy and (I assume although I don’t have personal knowledge) astrometry, and compressed sensing was an extremely hot field a while back.

  But RBCs are weird squishy things, and they fill the bloodstream quite densely, and ChatGPT estimates that they’re spaced about 20µm apart and that, when confined to a capillary, they’re about 7µm long. (And that sounds at least plausibly correct to me.)

  So, even ignoring the much worse scattering properties of RBCs, they not nearly as sparse. You mostly lose a whole dimension of sparseness and up trying to resolve the entire capillary. Which seems possible but much harder. Unfortunately, brain capillaries are about 40µm apart, so the result might be a mess.

  The article did not say what wavelength they’re using or what their native (wavelength/2) resolution is.

  by amluto
• > The bubbles themselves are pockets of sulfur hexafluoride encapsulated in lipid shells.

  The high resolution images were generated by injecting sparse bubbles of this contrast agent. How sparse are they? Is the image we see a stacked set of many bubbles over time composited together?

  Their aspirations at the end of doing this without the bubbles are great, but there’s a big “now draw the rest of the owl” energy around that leap. The first technique relies entirely on the bubbles, but they provide no explanation for how they think this could be achievable without the bubbles other than vaguely saying that technology is advancing.

  by Aurornis
• Cool work and proof of concept, and very excited to see where this goes. However, I do think there is enough exaggeration and missing information here that it warrants some critical appraisal. What's really missing is a comparison and validation with any existing medical imaging tech. Whole brain, contrast-free neurovascular imaging is essentially solved with MRI, why not run a scan and compare? Ultrasound is of course portable and less expensive, but MRIs are actually widely available in most cities at reasonable cost for medical workflows, and low-field brain MRI is addressing the portability and cost issues to some extent. I guess they are pitching this as a wearable "telepathy" device, which I think appropriately differentiates their product, but of course, this wording also invokes a framing that "you won't / don't need to know how it works," which invites skepticism and a higher bar for validation in my view.
  by thaw13579
• Even low-dose ultrasound (what they use on pregnant woman) results in ultrastructural changes in brains [0], specifically at the nodes of Ranvier (the gaps between myelin along axons). See also [1] for a review.

  [0] Ellisman MH, Palmer DE, André MP (1987), "Diagnostic levels of ultrasound may disrupt myelination," Experimental Neurology 98:78–92 https://pubmed.ncbi.nlm.nih.gov/3308504/

  [1] Quarato, C.M.I., Lacedonia, D., Salvemini, M., Tuccari, G., Mastrodonato, G., Villani, R., Fiore, L.A., Scioscia, G., Mirijello, A., Saponara, A. and Sperandeo, M., 2023. A review on biological effects of ultrasounds: key messages for clinicians. Diagnostics, 13(5), p.855. https://pmc.ncbi.nlm.nih.gov/articles/PMC10001275/

  by davi