[nick238]

From the bubble center plot, I'm guessing that the bubbles are separated on average about a few mm apart? Taking the other comment's guess at face value, you're going from about 2 mm to 20 um, so 2 orders of magnitude. Air (technically SF6 in the article) and water (RBC is close enough) have acoustic impedances that differ by 3.5 orders of magnitude.

My assumptions here are *extremely generous*, i.e. favorable to the "oh, we'll just make it work with natural contrast", and even then, they can't hand wave 5-6 orders of magnitude of improvement. Furthermore, because of the use of super resolution, I'm guessing there's some exponential factor in there, i.e. double the density of bubbles/tracking points past some critical limit, then you need 8x the data to reconstruct things.

[Aurornis]

> From the bubble center plot, I'm guessing that the bubbles are separated on average about a few mm apart?

The page is vague so I can't tell. I think the images they're showing are actually a composite of many bubbles tracked through the vasculature.

They say this:

> As bubbles flow through the vasculature, we accumulate millions of these positions and stack them into a single image with detail finer than the wavelength.

And the rendering showing the bubble centers they're tracking only shows a few small points moving at a time.

I think that the amazing animation they produced at the top is actually a composite of many different trackings, not an actual representation of what they capture in real-time.