The use of non-invasive imaging techniques in dermatology has been reported to improve the diagnostic accuracy and the practice of biopsies, and at the same time to reduce the need for tissue excision. However, the current clinically-available imaging techniques do not yet entirely meet the need for early and accurate, non-invasive detection of all skin cancers. A handheld line-field confocal optical coherence tomography (LC-OCT) device has been designed for high-resolution non-invasive imaging of human skin, in vivo. LC-OCT delivers tomographic images in real-time (10 frames/s) with a quasi isotropic spatial resolution of ~ 1 μm, revealing a comprehensive morphological mapping of skin tissues at a cellular level, down to a depth of ~500 μm. The device has been applied to the in vivo imaging of various skin lesions. Surgical excisions of the lesions have then been performed followed by tissue processing to realize H&E-stained histopathological images. The spatial resolution, orientation, and imaging contrast mechanism of the LC-OCT images have allowed for a good level of similarity with the conventional histopathological images. LC-OCT was able to show most of the histopathological elements that allow for medical diagnosis. Using handheld LC-OCT as an adjunct tool in dermatology could help improve clinical diagnostic accuracy, allowing for the early detection of malignant skin tumors and a reduction in the number of surgical excisions of benign lesions.
An improved optical coherence tomography (OCT) technique called line-field confocal OCT (LC-OCT) has been developed for high-resolution skin imaging. Combining the principles of time-domain OCT and confocal microscopy with line illumination and detection, LC-OCT acquires multiple A-scans in parallel with dynamic focusing. With a quasi isotropic resolution of ∼ 1 μm, the LC-OCT images reveal a comprehensive structural mapping of skin, in vivo, at the cellular level down to a depth of ∼ 500 μm. LC-OCT images of various skin lesions, including carcinomas and melanomas, are found to well correlate with histopathological images. LC-OCT could significantly improve clinical diagnostic accuracy, while reducing the number of biopsies of benign lesions.
An optical technique called line-field confocal optical coherence tomography (LC-OCT) is introduced for high-resolution, noninvasive imaging of human skin in vivo. LC-OCT combines the principles of time-domain optical coherence tomography and confocal microscopy with line illumination and detection using a broadband laser and a line-scan camera. LC-OCT measures the echo-time delay and amplitude of light backscattered from cutaneous microstructures through low-coherence interferometry associated with confocal spatial filtering. Multiple A-scans are acquired simultaneously while dynamically adjusting the focus. The resulting cross-sectional B-scan image is produced in real time at 10 frame / s. With an isotropic spatial resolution of ∼1 μm, the LC-OCT images reveal a comprehensive structural mapping of skin at the cellular level down to a depth of ∼500 μm. LC-OCT has been applied to the imaging of various skin lesions, in vivo, including carcinomas and melanomas. LC-OCT images are found to strongly correlate with conventional histopathological images. The use of LC-OCT as an adjunct tool in medical practice could significantly improve clinical diagnostic accuracy while reducing the number of biopsies of benign lesions.
Nephropathic cystinosis (NC) is a rare autosomal recessive storage disease characterized by the lysosomal accumulation of cystine crystals throughout the body, particularly in blood cells, the cornea, skin, kidneys, the central nervous system, and the muscles. The skin and the cornea are the most accessible sites to explore, and in vivo reflectance confocal microscopy (IVCM) helps identify crystals in both but does not provide any information to help define their composition. Raman spectroscopy (RS) allows cystine to be easily recognized thanks to its characteristic signature with a band at 499 cm −1 . Two dermatology confocal microscopes were used to visualize crystals in both the skin and the ocular surface of a cystinosis patient, and an ex vivo Raman examination of a skin biopsy and of the cornea was performed and removed during a corneal graft to confirm the cystine composition of the crystals. Recently, RS has been performed in vivo and coupled with IVCM. In the future, it is suggested that crystals in NC and other deposits in storage diseases could be identified with this noninvasive in vivo technique that combines IVCM to recognize the deposits and RS to confirm their chemical nature.