Optical coherence tomography (OCT) is a noninvasive, high-speed, and label-free imaging technique, providing 2D and 3D depth-resolved structures of biological tissue. In this study, we utilized a portable OCT system for in vivo studies of skin diseases and the evaluation of laser treatment outcome. A handheld probe with a light weight of 210 g is implemented for scanning arbitrary skin locations. To acquire en-face images at various skin depths, a segmentation algorithm was developed to identify skin surface and the boundary between the epidermis and dermis layers. According to the segmentation algorithm, skin parameters can be estimated including the thickness of stratum corneum, the thickness of epidermis, pore/hair follicle diameter, collagen concentration, and skin roughness. Moreover, the OCT images and skin parameters are used for clinical studies of skin diseases such as rosacea and psoriasis. In addition, the proposed method is utilized for observation and evaluation of laser treatment outcome in vivo. The results illustrate that such a portable OCT system could be potential for clinical diagnoses of skin diseases and laser treatment.
The diagnosis and treatment of dermatological diseases has always been valued, and the laser therapy is one of the main methods for the treatment of skin diseases. Optical Coherence Tomography (OCT) is a non-invasive, label-free, high-resolution and high-speed imaging technique, which is very suitable as a diagnostic tool in dermatology. In this study, we developed an Ultrahigh-Resolution OCT system (UHR-OCT), with below 2 μm in both axial and lateral resolution in tissue. The system is implemented to observe skin microstructure and layering, and to investigate postoperative follow-up of laser therapy. The results show that the developed UHR-OCT system can clearly distinguish the microstructure and layering of the skin, meaning that the system is well-suitable for skin diagnosis. In addition, we also investigated the photodamage such as LIOB in the tracking of laser treatment, which confirmed the value of UHR-OCT system in dermatology and laser treatment.
In this study, a portable and ultrahigh-resolution OCT (UHR-OCT) system is developed, and the axial and transverse resolutions are approximately 2 and 5 m, respectively. Although picosecond lasers are widely used for clinical treatment, it is difficult to predict and observe the treatment outcome. The developed UHR-OCT system is implemented to observe the photodamage induced by the picosecond laser and the laser-induced optical breakdown (LIOB) can be observed. Furthermore, the recovery process is studied and compared by UHR-OCT. The results indicate that the UHR-OCT system can clearly identify the skin structures, and the induced photodamage can be quantitatively evaluated.
Several optical technologies have been demonstrated as potential diagnostic tools for skin imaging, such as reflectance confocal microscopy (RCM) and optical coherence tomography (OCT). Although RCM could support cellular-level imaging, OCT could provide a larger field of view and a longer imaging depth than RCM. To quantitatively evaluate the skin condition with OCT, it is essential to develop an algorithm extracting different features, for example, the epidermis thickness and the optical characteristic of the epidermis. Although various segmentation algorithms have been proposed, most of the golden standards used involve the delineation of the boundary manually, where the labeling is highly relied on clinicians' experience and might vary among different physicians and the physician him or herself. Therefore, in this study, we collected skin OCT images of different sites from 20 subjects using a portable spectral-domain OCT system. The contrast of the OCT images can be effectively improved by optical attenuation coefficient (OAC) computation. This enables the development of a fully automatic segmentation algorithm, providing the parameters such as the (i) epidermis thickness and the (ii, iii) roughness of the boundary between the epidermis and air as well as the epidermis and dermis. Also, the (iv, v) OAC coefficients of the epidermis and upper dermis layer are available. Collectively, the developed algorithm supports the quantitative analysis of the five parameters across the imaging site with volumetric OCT imaging. We believe the developed algorithm can facilitate the implementation of skin OCT imaging for aesthetic medicine as a modality for objective pre- and post-treatment evaluation.
In this study, we compared the photothermal effects induced by the pulsed lasers including a fractional CO2 laser (=10600 nm) and a nanosecond Nd:YAG laser (=1064 nm). To investigate the induced photothermal effect, a spectral-domain optical coherence tomography (SD-OCT) system with a central wavelength of 840 nm was used to acquire 3D images of skin before and after the laser treatment. From the OCT results, the microscopic ablation zone (MAZ) resulted from the fractional CO2 laser can be identified that caused a stripe-shape photodamage on skin, ranging from the epidermis layer to the dermis layer. In contrast, the intra-dermal laser-induced optical breakdown (LIOB) induced by the nanosecond pulsed laser can also be observed from the OCT results.
Optical coherence tomography (OCT) can noninvasively reconstruct the three-dimensional microstructure of skin and
OCT has been commonly used for clinical studies. Additionally, the functional imaging abilities have been intensively
investigated in the past few years such as angiography, spectroscopy, polarization, elasticity, etc. The previous reports
have demonstrated that OCT can be a powerful tool for diagnoses of skin disorders. Vitiligo is a skin disorder by losing
the pigment and the skin patches become white and have sharp margins. Generally, the patches start on the skin areas
which are exposed to the sun. However, it is difficult to be identified before skin becomes white. Therefore, an imaging
tool is required for diagnosis of the early-stage skin vitiligo. In this study, we use OCT for in vivo imaging of skin vitiligo
and OCT is able to identify the loss of pigment in the early stage. The results demonstrated OCT could be a potential tool
for the diagnosis of the early-stage vitiligo.
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