Three-Mode Skin Probe Detects Cancer

A new device could potentially allow doctors to get a clearer picture of cancerous skin lesions and reduce the number of unnecessary biopsies.

A team at the University of Texas at Austin has developed a probe that combines three distinct spectroscopy methods to measure the properties of skin tissue: Raman spectroscopy, diffuse reflectance spectroscopy and laser-induced fluorescence spectroscopy. The 3-in-1 device offers a fast, comprehensive and noninvasive examination of melanoma and other skin cancer lesions.

The probe reveals information invisible to the human eye that can offer a better screening tool for cancer and eliminate many negative biopsies, according to the researchers. They noted that as normal skin becomes cancerous, cell nuclei enlarge, the top layers of skin thicken, and the skin cells can increase their consumption of oxygen and become disorganized. These changes alter the way light interacts with the tissue.

The figure is an exploded view of the filtered and lensed multispectroscopy probe by EmVision LLC. The cones illustrate how the Raman laser excitation region (red cone at distal tip) and Raman collection region (blue cone at distal tip, only one of seven cones shown for clarity) converge and intersect at the face of the lens. The figure also shows how the light is angled toward the green and yellow fibers used for diffuse reflectance and intrinsic fluorescence modalities, thereby collecting spectral data from all three spectroscopies from basically the same location. Courtesy of EmVision LLC.

In particular, diffuse optical spectroscopy can be sensitive to absorption by proteins such as hemoglobin, while Raman spectroscopy is sensitive to vibrational modes of chemical bonds, including those found in connective tissues, lipids and cell nuclei.

At present, the only definitive way to diagnose skin cancer is to perform a biopsy, according to the researchers.

However, determining which lesions to biopsy can be imprecise: For every case of skin cancer detected, roughly 25 negative biopsies are performed. The researchers noted that this can be quite expensive and sometimes unnecessarily time consuming.

“Skin is a natural organ to apply imaging and spectroscopy devices to because of its easy access,” said researcher James Tunnell, an associate professor of biomedical engineering at UT. “This probe that is able to combine all three spectral modalities is the next critical step to translating spectroscopic technology.”

The device is now being tested in clinical trials.

The research was published in Review of Scientific Instruments (doi: 10.1063/1.4890199).