Two new handheld optical imaging devices can detect and measure the extent of skin cancer tumors, particularly melanoma, say their developers.
One packs three different spectroscopic techniques—Raman spectroscopy, diffuse reflectance spectroscopy, and laser-induced fluorescence spectroscopy—into a single probe the size of a pen, connected to supporting equipment on a portable utility cart. In about four and a half seconds, it can scan the surface of the skin and detect which lesions are most likely cancerous. The diagnosis will have to be confirmed by a biopsy, but the device should be able not only to detect cases of skin cancer at early stages but also to rule out cancer in some suspected cases. That should, the developers hope, reduce the estimated $6 billion worth of negative skin cancer biopsies performed in the United States every year.
A paper about the device was published in the August issue of Review of Scientific Instruments. The probe is being tested in pilot clinical trials. A news release from the American Institute of Physics, which publishes Review of Scientific Instruments, has details.
The other device specifically targets melanoma, the deadliest form of skin cancer. It measures how deeply a melanoma tumor extends into the skin, which can be useful for diagnosis and for planning surgery or other treatment. Earlier attempts at high-resolution optical methods haven’t worked, said Lihong Wang, PhD, the Gene K. Beare Distinguished Professor of Biomedical Engineering at Washington University in St. Louis:
None are really sufficient to provide the two- to four-millimeter penetration that’s at least required for melanoma diagnosis, prognosis, or surgical planning.
Dr. Wang led the Washington University team that developed the device and is senior author of a paper about it that was published this week in Optics Letters. He was quoted in a news release from The Optical Society, publisher of the journal.
Other imaging methods aren’t much better, the researchers said. Ultrasound doesn’t have enough image contrast, and neither MRI nor PET offers enough resolution. So Dr. Wang’s team turned to photoacoustics. Laser light shone onto and around the tumor is converted to high-frequency acoustic waves, which penetrate better than light with less scattering. The device’s detector turns the acoustic signal into a three-dimensional image.
Testing on artificial tumors and on tumors in mice has shown that the device can accurately measure a tumor’s entire volume, which has not previously been possible, at least noninvasively. Tests on human patients have begun.
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