1. Articles from Meng-Tsan Tsai

    1-24 of 49 1 2 »
    1. A Generic Framework for Fourier-Domain Optical Coherence Tomography Imaging: Software Architecture and Hardware Implementations

      A Generic Framework for Fourier-Domain Optical Coherence Tomography Imaging: Software Architecture and Hardware Implementations

      Fourier-domain optical coherence tomography (FD-OCT), including spectral-domain OCT (SD-OCT) and swept-source OCT (SS-OCT), allows the volumetric imaging of the tissue architecture with a faster speed and higher detection sensitivity than does time-domain OCT. Although the hardware implementations of SD-OCT and SS-OCT are different, these technologies share very similar signal processing steps for image reconstruction. In this study, we developed hardware implementations and software architectures to design a generic framework for FD-OCT. For SD-OCT systems, an external synchronization approach was used to realize a data acquisition schematic similar to that used in SS-OCT by carefully managing the timing clocks in the ...

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    2. Imaging devices, systems, and methods of operation for acoustic-enhanced optical coherence tomography

      Imaging devices, systems, and methods of operation for acoustic-enhanced optical coherence tomography

      The present invention provides imaging devices, systems, and methods of operation for acoustic-enhanced optical coherence tomography. The systems coordinate imaging devices, optical coherence tomography (OCT), and pulsed ultrasound (FUS) and or pulsed ultrasound (PUS) to enhance the contrast of images. Moreover, the systems improve in vivo diagnosis and drug release through the utilization of sonographic enhancers such as microbubbles (MBs).

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    3. Optical coherence tomography/angiography-guided tumor ablation with a continuous-wave laser diode

      Optical coherence tomography/angiography-guided tumor ablation with a continuous-wave laser diode

      Laser ablation can be an effective modality for treatment, but it is complicated to apply continuous-wave (CW) light sources for laser ablation because of the unpredictable photothermal damage. In this study, an integrated theranostic system combining a low-cost CW laser diode with optical coherence tomography (OCT)/angiography (OCTA) was utilized for the in vivo ablation of tumor tissues. To examine the effect of laser exposure on tissue scattering characteristics, the OCT backscattering intensities of non-ablated and ablated tissues were analyzed, and the effect on the skin microvasculature produced by laser ablation was quantitatively evaluated. Moreover, the integrated system and the ...

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    4. Early detection of enamel demineralization by optical coherence tomography

      Early detection of enamel demineralization by optical coherence tomography

      Enamel is the outermost layer of the tooth that protects it from invasion. In general, an acidic environment accelerates tooth demineralization, leading to the formation of cavities. Scanning electron microscopy (SEM) is conventionally used as an in vitro tool for the observation of tooth morphology changes with acid attacks. Yet, SEM has intrinsic limitations for the potential application of in vivo detection in the early demineralization process. In this study, a high-resolution optical coherence tomography (OCT) system with the axial and transverse resolutions of 2.0 and 2.7 μm in teeth has been utilized for characterizing the effect of ...

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    5. Ultrahigh-resolution optical coherence tomography/angiography with an economic and compact supercontinuum laser

      Ultrahigh-resolution optical coherence tomography/angiography with an economic and compact supercontinuum laser

      In this study, a Q-switch pumped supercontinuum laser (QS-SCL) is used as a light source for in vivo imaging via ultrahigh-resolution optical coherence tomography and angiography (UHR-OCT/OCTA). For this purpose, an OCT system based on a spectral-domain detection scheme is constructed, and a spectrometer with a spectral range of 635 − 875 nm is designed. The effective full-width at half maximum of spectrum covers 150 nm, and the corresponding axial and transverse resolutions are 2 and 10 µm in air, respectively. The relative intensity noise of the QS-SCL and mode-locked SCL is quantitatively compared. Furthermore, a special processing algorithm is ...

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    6. Non-Invasive Quantification of the Growth of Cancer Cell Colonies by a Portable Optical Coherence Tomography

      Non-Invasive Quantification of the Growth of Cancer Cell Colonies by a Portable Optical Coherence Tomography

      Investigation of tumor development is essential in cancer research. In the laboratory, living cell culture is a standard bio-technology for studying cellular response under tested conditions to predict in vivo cellular response. In particular, the colony formation assay has become a standard experiment for characterizing the tumor development in vitro. However, quantification of the growth of cell colonies under a microscope is difficult because they are suspended in a three-dimensional environment. Thus, optical coherence tomography (OCT) imaging was develop in this study to monitor the growth of cell colonies. Cancer cell line of Huh 7 was used and the cells ...

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    7. In vivo detection of UV-induced acute skin effects using optical coherence tomography

      In vivo detection of UV-induced acute skin effects using optical coherence tomography

      Ultraviolet (UV) rays have been identified as a carcinogen with long-term irradiation and are an important risk factor for skin cancer. Here, we report the use of optical coherence tomography/optical coherence tomography angiography (OCT/OCTA) to study acute UV-induced effects on skin in vivo . To understand the relationship between the acute effects and irradiated UV power density, three groups were irradiated with different power densities in our experiments. Furthermore, the same skin area was repeatedly scanned with OCT during UV irradiation to investigate the progress of the induced acute effects and after irradiation for observation of skin recovery. Subsequently ...

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    8. Extending the depth of focus of fiber-optic optical coherence tomography using a chromatic dual-focus design

      Extending the depth of focus of fiber-optic optical coherence tomography using a chromatic dual-focus design

      We report a dual-focus fiber-optic probe designed to extend depth of focus (DOF) in high-resolution endoscopic optical coherence tomography. We exploited the broad spectral bandwidth of a supercontinuum source and, in the fiber probe, the foci of the 750–1000 nm and 1100–1450 nm inputs were axially chromatically shifted. The interference signals from the two spectral bands were measured with a Si camera-based spectrometer and an InGaAs camera-based spectrometer, respectively. We verified the feasibility of the design using a phantom composed of microparticles and swine small intestine tissue ex vivo . The results showed that a transverse resolution below 5 ...

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    9. Assessment of temporary cerebral effects induced by focused ultrasound with optical coherence tomography angiography

      Assessment of temporary cerebral effects induced by focused ultrasound with optical coherence tomography angiography

      Focused ultrasound (FUS) in combination with microbubbles temporally and locally increases the permeability of the blood-brain barrier (BBB) for facilitating drug delivery. However, the temporary effects of FUS on the brain microstructure and microcirculation need to be addressed. We used label-free optical coherence tomography (OCT) and OCT angiography (OCTA) to investigate the morphological and microcirculation changes in mouse brains due to FUS exposure at different power levels. Additionally, the recovery progress of the induced effects was studied. The results show that FUS exposure causes cerebral vessel dilation and can be identified and quantitatively analyzed via OCT/OCTA. Micro-hemorrhages can be ...

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    10. Noninvasive structural and microvascular anatomy of oral mucosae using handheld optical coherence tomography

      Noninvasive structural and microvascular anatomy of oral mucosae using handheld optical coherence tomography

      In this study, we demonstrated the feasibility of using a handheld optical coherence tomography (OCT) for in vivo visualizations of the microstructural and microvascular features of various oral mucosal types. To scan arbitrary locations of the oral mucosa, a scanning probe was developed, composed of a probe body fabricated by a 3D printer, miniaturized two-axis galvanometer, relay lenses, and reflective prism. With a 3D printing technique, the probe weight and the system volume were greatly reduced, enabling the effective improvement of imaging artifacts from unconscious motion and system complexity. Additionally, in our design, the distal end of the probe can ...

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    11. Determination of Coefficient of Thermal Expansion in High Power GaN-Based Light-Emitting Diodes via Optical Coherent Tomography

      Determination of Coefficient of Thermal Expansion in High Power GaN-Based Light-Emitting Diodes via Optical Coherent Tomography

      One of the most challenging issues when operating a high-power light-emitting diode (LED) is to conduct appropriate packaging materials for the reliable thermal management of the entire device. Generally, the considerable amount of heat produced around the junction area of the LED would transfers to the entire device, and causes thermal expansion in the packaging material. It induces strain inevitably, and hinders the output performances and possible applications of high-power LEDs. The coefficient of thermal expansion (CTE) is a physical quantity that indicates the expansion to which value a material will be upon heating. Therefore, as far as an advancement ...

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    12. Using Optical Coherence Tomography to Identify of Oral Mucosae with 3D-Printing Probe

      Using Optical Coherence Tomography to Identify of Oral Mucosae with 3D-Printing Probe

      Biomedical materials have different optical properties (e.g. absorption) for different wavelengths. Therefore, probing biomedical materials with multiple wavelengths not only can get in-depth understanding of the detected biomedical materials but also can differentiate the detected biomedical materials. To achieve this purpose, in this conference paper, we present our initial results of building up a portable multiple-wavelength biomedical sensing system. At this initial phase, we assembled this kind of system with multiple wavelengths of light sources and photodetectors and preliminarily tested the absorbance of the glucose solutions with different concentrations. The result shows good linearity of the absorbance of the ...

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    13. Contrast-enhanced optical coherence microangiography with acoustic-actuated microbubbles

      Contrast-enhanced optical coherence microangiography with acoustic-actuated microbubbles

      In this study, we propose to use gas-filled microbubbles (MBs) simultaneously actuated by the acoustic wave to enhance the imaging contrast of optical coherence tomography (OCT)-based angiography. In the phantom experiments, MBs can result in stronger backscattered intensity, enabling to enhance the contrast of OCT intensity image. Moreover, simultaneous application of low-intensity acoustic wave enables to temporally induce local vibration of particles and MBs in the vessels, resulting in time-variant OCT intensity which can be used for enhancing the contrast of OCT intensitybased angiography. Additionally, different acoustic modes and different acoustic powers to actuate MBs are performed and compared ...

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    14. Noninvasive imaging of oral mucosae with optical coherence tomography

      Noninvasive imaging of oral mucosae with optical coherence tomography

      In this study, a swept-source optical coherence tomography (OCT) system is developed for in vivo visualization of structural and vascular morphology oral mucosa. For simplification of optical probe fabrication, probe weight, and system setup, the body of the scanning probe is fabricated by a 3D printer to fix the optical components and the mechanical scanning device, and a partially reflective slide is attached at the output end of probe to achieve a common-path configuration. Aside from providing the ability of 3D structural imaging with the developed system, 3D vascular images of oral mucosa can be simultaneously obtained. Then, different locations ...

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    15. Study on laser-assisted drug delivery with optical coherence tomography

      Study on laser-assisted drug delivery with optical coherence tomography

      The nail provides a functional protection to the fingertips and surrounding tissue from external injuries. Nail plate divided into three layers including dorsal, intermediate, and ventral layers. The dorsal layer consists of compact, hard keratins, limiting topical drug delivery through the nail. In this study, we investigate the application of fractional CO 2 laser that produces arrays of microthermal ablation zones (MAZs) to facilitate drug delivery in the nails. Moreover, optical coherence tomography (OCT) is implemented for real-time monitoring of the laser–skin tissue interaction, sparing the patient from invasive surgical sampling procedure. Observations of drug diffusion through the induced ...

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    16. Acoustic-actuated optical coherence angiography

      Acoustic-actuated optical coherence angiography

      Optical coherence tomography (OCT) angiography requires high sensitivity and image penetration for detailed microvascular monitoring. Unfortunately, no effective contrast-medium-enhanced scheme is currently available for imaging improvement. We here propose the simultaneous use of gas-filled microbubbles (MBs) and acoustic actuation to enhance the imaging contrast of OCT angiography. OCT-synchronized acoustic actuation was applied in the presence of MBs, and different moving object tracking angiographic algorithms were tested in in vitro tubing and in vivo mouse experiments. This scheme significantly enhanced the OCT angiography performance, including its sensitivity and penetration, and should advance the utilization of OCT as an effective microvascular diagnostic ...

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    17. Evaluation of Laser-Assisted Trans-Nail Drug Delivery with Optical Coherence Tomography

      Evaluation of Laser-Assisted Trans-Nail Drug Delivery with Optical Coherence Tomography

      The nail provides a functional protection to the fingertips and surrounding tissue from external injuries. The nail plate consists of three layers including dorsal, intermediate, and ventral layers. The dorsal layer consists of compact, hard keratins, limiting topical drug delivery through the nail. In this study, we investigate the application of fractional CO 2 laser that produces arrays of microthermal ablation zones (MAZs) to facilitate drug delivery in the nails. We utilized optical coherence tomography (OCT) for real-time monitoring of the laser–skin tissue interaction, sparing the patient from an invasive surgical sampling procedure. The time-dependent OCT intensity variance was ...

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    18. In vivo investigation of temporal effects and drug delivery induced by transdermal microneedles with optical coherence tomography

      In vivo investigation of temporal effects and drug delivery induced by transdermal microneedles with optical coherence tomography

      Transdermal drug-delivery systems (TDDS) have been a growing field in drug delivery because of their advantages over parenteral and oral administration. Recent studies illustrate that microneedles (MNs) can effectively penetrate through the stratum corneum barrier to facilitate drug delivery. However, the temporal effects on skin and drug diffusion are difficult to investigate in vivo . In this study, we used optical coherence tomography (OCT) to observe the process by which MNs dissolve and to investigate the temporal effects on mouse skin induced by MNs, including the morphological and vascular changes. Moreover, the recovery process of the skin was observed with OCT ...

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      Mentions: Meng-Tsan Tsai
    19. Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode

      Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode

      Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in ...

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    20. Optical inspection of solar cells using phase-sensitive optical coherence tomography

      Optical inspection of solar cells using phase-sensitive optical coherence tomography

      The inspection and measurement of solar cells has become an important technique in evaluating the efficiency and quality of solar cell devices. Currently, surface defect detection of solar cells can be achieved by several approaches such as machine vision, photoluminescence, and electroluminescence imaging techniques. Nevertheless, it is still difficult to inspect the inner structures of solar cells. In response to this need, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have become common techniques for investigating the nanostructures of solar cells. However, both carry the disadvantages of destructive imaging, high cost, and a small inspection area. Moreover, it is ...

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    21. Fabrication of a novel dissolving polymer microneedle patch for transdermal drug delivery

      Fabrication of a novel dissolving polymer microneedle patch for transdermal drug delivery

      Polymer microneedles (MNs) have gained increasing attention as a minimally invasive method for efficiently delivering drugs and vaccines in a patient-friendly manner. Herein, an easy and mild process with O2 plasma treatment was used to fabricate polyvinylpyrrolidone (PVP)/polyvinyl alcohol (PVA) MN patches, and efficient, sustained transdermal delivery was achieved. The diffusion rate of the entrained molecules could be controlled by adjusting the ratio of PVP/PVA. Optical coherence tomography was used to monitor the in vitro penetration in real time and to measure the penetration depth. Rhodamine 6G and fluorescein isothiocyanate-labeled bovine serum albumin (BSA-FITC) were used to explore ...

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    22. Feasibility of ablative fractional laser-assisted drug delivery with optical coherence tomography

      Feasibility of ablative fractional laser-assisted drug delivery with optical coherence tomography

      Fractional resurfacing creates hundreds of microscopic wounds in the skin without injuring surrounding tissue. This technique allows rapid wound healing owing to small injury regions, and has been proven as an effective method for repairing photodamaged skin. Recently, ablative fractional laser (AFL) treatment has been demonstrated to facilitate topical drug delivery into skin. However, induced fractional photothermolysis depends on several parameters, such as incident angle, exposure energy, and spot size of the fractional laser. In this study, we used fractional CO 2 laser to induce microscopic ablation array on the nail for facilitating drug delivery through the nail. To ensure ...

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    23. Investigation of temporal vascular effects induced by focused ultrasound treatment with speckle-variance optical coherence tomography

      Investigation of temporal vascular effects induced by focused ultrasound treatment with speckle-variance optical coherence tomography

      Focused ultrasound (FUS) can be used to locally and temporally enhance vascular permeability, improving the efficiency of drug delivery from the blood vessels into the surrounding tissue. However, it is difficult to evaluate in real time the effect induced by FUS and to noninvasively observe the permeability enhancement. In this study, speckle-variance optical coherence tomography (SVOCT) was implemented for the investigation of temporal effects on vessels induced by FUS treatment. With OCT scanning, the dynamic change in vessels during FUS exposure can be observed and studied. Moreover, the vascular effects induced by FUS treatment with and without the presence of ...

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    24. Two-Level Optical Coherence Tomography Scheme for Suppressing Spectral Saturation Artifacts

      Two-Level Optical Coherence Tomography Scheme for Suppressing Spectral Saturation Artifacts

      We demonstrate a novel method for reducing saturation artifacts in spectral-domain optical coherence tomography (SD-OCT) systems. This method is based on a two-level SD-OCT system with a dual-line charge-coupled device (CCD) camera. We compensate the saturated signal detected by the first line using the unsaturated signal detected by the second line. The Fourier transform of the compensated spectrum shows effective suppression of saturation artifacts. This method was also successfully performed on phantom material and skin on a human finger. Our method causes neither back-scattering power loss nor signal-to-noise ratio (SNR) degradation. The only difference between the traditional system and our ...

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    1-24 of 49 1 2 »
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