New microscope delves beneath skin to detect cancer
ROME – A new type of laser-scanning confocal microscope provides more information than previous versions and holds promise for skin cancer diagnostics.
Unlike typical laser-scanning confocal microscopes that take 3-D images of thick tissue samples by visualizing thin slices one layer at a time, the new device gathers spectrographic information at a wide spectral range – approximately 0.5 to 2.5 µm – for every point in the sample, and all in a single scan. This spectroscopic fingerprinting was detailed online Aug. 18 in AIP Advances (doi: 10.1063/1.3631661).
Physicists at Consiglio Nazionale delle Ricerche (CNR), in collaboration with a dermatologist, demonstrated the technology by taking high-resolution images of the edge of a silicon wafer and of metallic letters painted onto a piece of silicon less than a half-millimeter wide. They also demonstrated that it is possible to apply this technique to a tissue sample – in this case, chicken skin – without destroying it.
An illustration of the CNR confocal microscope showing the 80-µm-wide images from a silicon/silicon dioxide calibration sample. The 10-µm periodical structure is made of 100-nm-thick SiO2 squares over a silicon substrate. The left image is obtained with the 580-nm wavelength. The scientists can compute the full-color image (right) by averaging the reflectivity intensities around the red, green and blue regions and associating a suitable RGB color map. The greatest reflectivity for silicon is depicted by the green-blue portion of the spectrum, while the greatest contribution of the SiO2 island is depicted by the red-infrared part. Courtesy of F.R. Bertani, L. Ferrari, S. Selci, ISC-CNR, unpublished results.
“The main aim of our effort is not only to produce typical histologic results without tissue removal and specific preparation, but also to obtain reliable functional data on the tissue from spectral analysis,” said Dr. Stefano Selci of CNR. “The potential impact can be wide and deep.”
Because the spectral region is vast, Selci explained, the innovation could affect many applications and contexts, including dermatology, cosmetology, endoscopy for recessed diagnosis of general tissues as well as semiconductors and any materials science research.
With further testing, the microscope could be used to detect early signs of melanoma, Selci said. “We are examining now a wide range of human skin samples ex vivo to accumulate experience on significant samples and to correlate confocal spectroscopy data to specific cell types and skin structures,” he said. “On the technical side, we have mainly to speed up acquisition times as needed for biological specimens: Our microscope has been realized from scratch to avoid any compromise, and we have to invent new solutions for our particular optical setup to transport the brilliant white laser beam.”
Until then, he said, it is suitable for nonmedical applications such as inspecting semiconductor surfaces.
MORE FROM PHOTONICS MEDIA