First Images of a Heart Injected With Liquid Metal

KentuckyFC writes "The early symptoms of many diseases show up first in the smallest blood vessels, but imaging the fine structure of these vessels is a tricky problem for medics. The most common way is to inject them with a contrast agent and use x-ray tomography to create a 3D image of their structure. This shows problems in the large vessels but not smaller ones. The problem is the lack of contrast. Conventional contrast agents are based on iodine, which has a high electron density and so better absorbs x-rays than other atoms. But a better solution would be to use a higher density fluid, such as a liquid metal. The obvious fears associated with toxicity and so forth mean this has never been tried. Until now. A team of Chinese biomedical engineers have created the world's first images of a pig's heart injected with gallium. This has a melting point of 29 degrees C, so it's a liquid at body temperature. And the results show the detailed structure of the tiniest blood vessels, revealing capillaries just 0.07 mm in diameter. That's significantly more detailed than is possible with iodine-based contrast agents. An important question is whether this technique will ever be possible in humans. The Chinese team seems optimistic. They say gallium is chemically inert, non-toxic to humans and can be injected and sucked out without leaving a residue. 'It suggests the possibility for localized in vivo vascular-enhanced radiological imaging in the near future.'"

Gallium = Sticky

[Iskender]

At least according to http://theodoregray.com/periodictable/Elements/031/index.s7.html [theodoregray.com] gallium and at least some of its alloys are really sticky, leaving residue on most anything. "Unfortunately, it stains your hands and is hard to get off, so I don't recommend it. In fact, it stains or sticks to just about anything, which is very irritating because it would otherwise make a very nice substitute for mercury where a liquid metal is called for."

I've used one of those gallium-containing fake-mercury thermometers myself, and after a few uses the liquid metal got stuck to the glass tube, and it never worked again. They could have made some better alloy of it or something, but that's not mentioned in the abstract, at least.

(Also, someone is actually using Medium? Impressive, I was compelled to use it for a course, and it was the most dead "social network" I've ever seen.)

Never been tried?

[TheCarp]

The problem is the lack of contrast. Conventional contrast agents are based on iodine, which has a high electron density and so better absorbs x-rays than other atoms. But a better solution would be to use a higher density fluid, such as a liquid metal. The obvious fears associated with toxicity and so forth mean this has never been tried.

So my mother was an X-Ray technition for 25 years, and was trained in the 70s. In fact, metals, if not this kind of "liquid metal" have not only been tried, but used. In fact, when she was working back in the 90s, she used to say that soft tissue x-rays back in the 50s were much sharper because of the better contrast they had.

Better....because it contained thorium. While it made amazing x-rays, it turned out to not be so good for the patients. Turns out those "harmless" alpha decays are a lot less harmless when they happen inside your body.

I never really looked up the specific contrast before, apparently mom got her decades wrong, but it was history for her too so that isn't too surprizing: http://en.wikipedia.org/wiki/Thorotrast [wikipedia.org]