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.
We have developed a multifunctional catheter-based OCT system, which provides architecture and birefringence information of biological tissue and allows volumetric imaging of the luminal part of the cervix. Preliminary imaging results of the in vivo human buccal mucosa and tongue were shown to validate the capabilities of volumetric imaging in the developed multifunctional OCT system, and further obtained the birefringence information by analyzing the polarization information of the OCT signal to implement the multifunctional OCT imaging.
In this study, a Swept-Source Optical Coherence Tomography (SS-OCT) system and a Raman fiber laser with high laser output are used to investigate the photothermal effect on biological tissue. An optical focuser is connected to the Raman fiber laser to focus the laser power on the specific area of the tissue. To simultaneously observe the induced photothermal effect, a dynamic algorithm is used in the process to produce dynamic image of the tissue from time-series OCT images. The results show that with dynamic images, we can identify the extent and area of laser ablation with time. Moreover, after merging the dynamic image and the original OCT image, we can indicate the ablated area in the tissue apart from the surrounding area without ablation.
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.
In this study, an ultrahigh resolution OCT(UHR-OCT) system is constructed, with 1.5 um axial resolution and 1.9 um lateral resolution in enamel. Despite the inverse relationship of clinical process, early-stage dental caries and calculus are both imaged as bright zones on the top of enamel yet cannot be distinguished in conventional OCT. The results indicate that early-stage caries and calculus can be detected and distinguished clearly in our developed UHR-OCT. We also compared the UHR-OCT images with the results obtained from commercial OCT to clarify the system performance. This work shows the potential for using UHR-OCT in early-stage dental detection.
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.
We demonstrated computational multi-directional optical coherence tomography to visualize the microstructural directionality of a tissue. It uses numerical sub-aperture masks to the spatial frequency spectrum of en face OCT signals. An OCT signal consists of the intensity and phase, and they are processed independently. By applying the sub-aperture masks with several directions to the intensity signal’s spectrum, we can determine the dominant en face direction of the microstructure. In addition, sub-resolution depth-orientation of the microstructure is obtained by sub-aperture processing of the OCT phase signal. The microstructural directionality of bovine Achilles tendon and chicken breast muscle samples were visualized.
A virtual multi-directional optical coherence tomography method to visualize directional microstructures of the tissue is demonstrated. The directional measurement is achieved by numerical aperture masks applied after the data acquisition. So multi-directional images are created only a single measurement with no hardware extension. By applying several types of aperture masks, we created not only multi-directional images but also multi-structural-frequency images. These images showed the difference appearance which come from the microstructural directionality of chicken breast muscle sample.
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