While optical coherence tomography (OCT) has proven immensely useful in both ophthalmology and dermatology, it has not been able to capture sufficiently detailed subcutaneous images to detect the early stages of cancer or to monitor skin cancer progression. But new laser technology is maximizing the quality of OCT imagery. It operates at a near-infrared (NIR) wavelength (1300 nm), allowing recording of 440,000 depth profiles per second—compared to 20,000 to 60,000 using standard OCT—and deeper penetration of skin tissue.
According to MUW researcher Rainer Leitgeb, the study's principal investigator, "The higher speed is necessary so that we do not lose contrast while we are imaging the details due to the patient moving. It gives us a detailed picture of the perfusion of the blood and the structure of vessels." He adds that his team is the first anywhere to "achieve this degree of detail to image the vascular system of human skin cancers."
The technology also enables understanding of how existing tumors are nourished, thereby providing a tool for development of targeted therapies.
|A basal cell carcinoma on a patient's forehead, imaged using (a) dermascopy, with square indicating the optical coherence tomography (OCT) field of view depicted in (b), where black and red bars indicate depth range for (c) and (d), respectively. (c) Intensity en-face mean projection for depth range in (b); dashed line indicates the tomogram position. (d) 2 × 2 mm en-face fly through the microvasculature starting from surface (see http://bcove.me/h2kra3do; video courtesy of Biomedical Optics Express). (e) Overlay of microcirculation on structural information.|
The researchers think their system has the most promise for clinical application in diagnosing and treating skin cancer, but that it could help doctors assess how quickly a tumor is likely to grow and spread, and to monitor the effectiveness of treatments such as topical chemotherapy. "Treatment monitoring may also be expanded toward inflammatory and auto-immune related dermatological conditions," says Cedric Blatter of MUW, lead author on the publication.1
Going forward, the researchers would like to increase the device's field of view so it can image the full lesion along with its border to healthy tissue. They are also working on speeding up the post-processing of the optical signal to enable live vasculature display and improving the portability of the system, which currently occupies an area about half the size of an office desk.
1. C. Blatter et al., Biomed. Opt. Exp., 3, 10, 2636–2646 (2012).