Making Tissue Temporarily Transparent.

• Position: University of Texas use glycerol to see through skin - Brief Article

By manipulating how light passes through tissue, a biomedical engineering research team at The University of Texas at Austin has taken a step toward what was once the realm of science fiction. The researchers have made tiny bits of flesh transparent for brief periods of time in the lab. In effect, they temporarily can create a window of tissue, allowing doctors to see up to five times deeper than they can at present. Although it hasn't yet been tested on human skin, the engineers say the process could have wide applications for medical diagnosis and new therapies.

Using injections of substances such as glycerol, they have succeeded in making small areas of rat or hamster skin nearly transparent for a period of 20 minutes or more. Glycerol is hygroscopic alcohol, which means it pulls water out of tissue. Glycerol often is used in cosmetics and for medical applications.

Ashley J. Welch, a professor of biomedical engineering and chief investigator on the project, explains that, "When we injected glycerol into the skin of a hamster, we could actually see a blood vessel which had not been visible." If the procedure works on human tissue, it has the potential to lead to improvements in a variety of diagnostic and therapeutic medical procedures ranging from laser surgery to the treatment of tumors. At present, therapeutic procedures that depend on accurately focusing lasers on a particular area--such as retinal surgery and the targeting of tumors and other laser procedures--are limited by the fact that a beam of light cannot pass directly through overlying tissue.

The new process has to do with refraction--the fact that light is scattered as it moves through skin. Welch says that the optical process could be compared to searching for an object obscured by a dense fog. When a searchlight is directed at the fog, the light is scattered in all directions, creating a...