Scientists say it is possible to create a three-dimensional image of the most deadliest form of skin cancer using a new imaging technology.
Melanoma is one of the less common types of skin cancer but it also the deadliest one. So far no imaging technique has been up to the task of defining the melanoma's boundaries accurately enough to guide surgery. Instead surgeons tend to cut well beyond the visible margins of the lesion in order to be certain they remove all the malignant tissue.
Two scientists of Washington University in St. Louis have developed imaging technologies to overcome this difficult problem.
Their solution combines an imaging technique developed by Lihong Wang, the Gene K. Beare Distinguished Professor of Biomedical Engineering, and a contrast agent developed by Younan Xia, the James M. McKelvey Professor of Biomedical Engineering.
Together the imaging technique and contrast agent produce images of startling three-dimensional clarity.
The imaging technique is based on the photoacoustic effect discovered by Alexander Graham Bell 100 years ago. Bell exploited the effect in what he considered his greatest invention ever, the photophone, which converted sound to light, transmitted the light and then converted it back to sound at the receiver.
In Bell's effect, the absorption of light heats a material slightly, typically by a matter of millikelvins, and the temperature rise causes thermoelastic expansion.
"Much the same thing happens. when you heat a balloon and it expands," Wang said.
If the light is pulsed at the right frequency, the material will expand and contract, generating a sound wave.
"We detect the sound signal outside the tissue, and from there on, it's a mathematical problem. We use a computer to reconstruct an image. We're essentially listening to a structure instead of looking at it," Wang added.
"Using pure optical imaging, it is hard to look deep into tissues because light is absorbed and scattered. The useful photons run out of juice within one millimeter," he further said.
The technology has been described in the July issue of journal ACS Nano.