How did scientists snap such a beautiful image of the blood vessels in a pig heart? They filled them with liquid gallium!
Over at Medium, the Physics Arxiv blog has a full account of the study:
"Conventional contrast agents are based on iodine because it has a high electron density and so absorbs x-rays. A more effective way to absorb X-rays is by using a denser fluid. But until now nobody had tried the obvious solution: using a liquid metal.
That’s where Qian and co come in. These guys have tried it for the first time with gallium, a metal which melts at about 29 degrees centigrade and so is liquid at body temperature. Gallium is also chemically stable and does not react with water at this temperature and so ought to flow easily through the vessels.”
Go read the whole thing!