1. Articles from Yoshiaki Yasuno

    1-24 of 134 1 2 3 4 5 6 »
    1. Clinical prototype of pigment and flow imaging optical coherence tomography for posterior eye investigation

      Clinical prototype of pigment and flow imaging optical coherence tomography for posterior eye investigation

      Measurements of the randomness of polarization (RP) obtained using polarization-sensitive optical coherence tomography (PS-OCT) are applied in several applications, and RP is attractive for posterior eye imaging. The addition of RP without retardation requires a minimal extension to standard OCT; therefore, we developed a prototype OCT system with a simplified scheme for RP measurement. A compact polarization-diversity receiver module is the only required hardware extension to a standard OCT system. All components were packed into the retinal scanning head. The degree-of-polarization uniformity and complex-decorrelation based OCT angiography were calculated using noise-corrected algorithms that accounted for the depth-dependent noise power. The ...

      Read Full Article
    2. Machine-learning based segmentation of the optic nerve head using multi-contrast Jones matrix optical coherence tomography with semi-automatic training dataset generation

      Machine-learning based segmentation of the optic nerve head using multi-contrast Jones matrix optical coherence tomography with semi-automatic training dataset generation

      A pixel-by-pixel tissue classification framework using multiple contrasts obtained by Jones matrix optical coherence tomography (JM-OCT) is demonstrated. The JM-OCT is an extension of OCT that provides OCT, OCT angiography, birefringence tomography, degree-of-polarization uniformity tomography, and attenuation coefficient tomography, simultaneously. The classification framework consists of feature engineering, k -means clustering that generates a training dataset, training of a tissue classifier using the generated training dataset, and tissue classification by the trained classifier. The feature engineering process generates synthetic features from the primary optical contrasts obtained by JM-OCT. The tissue classification is performed in the feature space of the engineered features ...

      Read Full Article
    3. Pixel-wise segmentation of severely pathologic retinal pigment epithelium and choroidal stroma using multi-contrast Jones matrix optical coherence tomography

      Pixel-wise segmentation of severely pathologic retinal pigment epithelium and choroidal stroma using multi-contrast Jones matrix optical coherence tomography

      Tissue segmentation of retinal optical coherence tomography (OCT) is widely used in ophthalmic diagnosis. However, its performance in severe pathologic cases is still insufficient. We propose a pixel-wise segmentation method that uses the multi-contrast measurement capability of Jones matrix OCT (JM-OCT). This method is applicable to both normal and pathologic retinal pigment epithelium (RPE) and choroidal stroma. In this method, “features,” which are sensitive to specific tissues of interest, are synthesized by combining the multi-contrast images of JM-OCT, including attenuation coefficient, degree-of-polarization-uniformity, and OCT angiography. The tissue segmentation is done by simple thresholding of the feature. Compared with conventional segmentation ...

      Read Full Article
    4. Comparison of intensity, phase retardation, and local birefringence images for filtering blebs using polarization-sensitive optical coherence tomography

      Comparison of intensity, phase retardation, and local birefringence images for filtering blebs using polarization-sensitive optical coherence tomography

      Polarization-sensitive optical coherence tomography (PS-OCT) allows the recording of depth-resolved polarimetric measurements. It has been reported that phase retardation and local birefringence images can noninvasively detect fibrotic area in blebs after glaucoma surgery. Evaluation of scar fibrosis in blebs is important not only for predicting bleb function, but also for planning revision trabeculectomy. Herein, we characterize the intensity, phase retardation, and local birefringence images of blebs using PS-OCT. A total of 85 blebs from 85 patients who had undergone trabeculectomy were examined. Both phase retardation and local birefringence images detected fibrotic changes in blebs after glaucoma surgery. Phase retardation images ...

      Read Full Article
    5. Simultaneous tissue birefringence and deformation measurement by polarization sensitive optical coherence elastography with active compression

      Simultaneous tissue birefringence and deformation measurement by polarization sensitive optical coherence elastography with active compression

      Polarization sensitive optical coherence tomography (PS-OCT) measures tissue birefringence, while optical coherence elastography (OCE) reveals the mechanical property of the tissue. Since both birefringence and mechanical properties are associated with tissue microstructures such as collagen, simultaneous PS-OCT and OCE measurement will provide useful insight for the tissue microstructures. In this paper, we present a combined PS-OCT and OCE technique. The PS-OCT is based on Jones matrix OCT theory. It measures a tomography of Jones matrix. Birefringence tomography is then deduced from the Jones matrix. The OCE is obtained with active tissue compression. The tissue compression was performed by a ring ...

      Read Full Article
    6. Objective evaluation of choroidal melanin contents with polarization-sensitive optical coherence tomography

      Objective evaluation of choroidal melanin contents with polarization-sensitive optical coherence tomography

      We non-invasively evaluated choroidal melanin contents in human eyes with PS-OCT. We calculated the percentage area of low DOPU in the choroidal interstitial stroma for Vogt-Koyanagi- Harada disease with sunset glow fundus, without sunset glow fundus, control group and tessellated fundus with high myopia. The mean percentage area of low DOPU in the sunset group was significantly lower than the other groups. PS-OCT provides an in vivo objective evaluation of choroidal melanin loss in vivo human eyes.

      Read Full Article
    7. Eye-motion-corrected optical coherence tomography angiography using Lissajous scanning

      Eye-motion-corrected optical coherence tomography angiography using Lissajous scanning

      To correct eye motion artifacts in en face optical coherence tomography angiography (OCT-A) images, a Lissajous scanning method with subsequent software-based motion correction is proposed. The standard Lissajous scanning pattern is modified to be compatible with OCT-A and a corresponding motion correction algorithm is designed. The effectiveness of our method was demonstrated by comparing en face OCT-A images with and without motion correction. The method was further validated by comparing motion-corrected images with scanning laser ophthalmoscopy images, and the repeatability of the method was evaluated using a checkerboard image. A motion-corrected en face OCT-A image from a blinking case is ...

      Read Full Article
    8. Generation and optimization of superpixels as image processing kernels for Jones matrix optical coherence tomography

      Generation and optimization of superpixels as image processing kernels for Jones matrix optical coherence tomography

      Jones matrix-based polarization sensitive optical coherence tomography (JM-OCT) simultaneously measures optical intensity, birefringence, degree of polarization uniformity, and OCT angiography. The statistics of the optical features in a local region, such as the local mean of the OCT intensity, are frequently used for image processing and the quantitative analysis of JM-OCT. Conventionally, local statistics have been computed with fixed-size rectangular kernels. However, this results in a trade-off between image sharpness and statistical accuracy. We introduce a superpixel method to JM-OCT for generating the flexible kernels of local statistics. A superpixel is a cluster of image pixels that is formed by ...

      Read Full Article
    9. Introduction to the feature issue on the 25 year anniversary of optical coherence tomography

      Introduction to the feature issue on the 25 year anniversary of optical coherence tomography

      This feature issue commemorates the approximately 25 year history of Optical Coherence Tomography (OCT), one of the most successful biophotonic technologies. While OCT has technological origins traceable to ultrafast laser development and fiber optic system test instrumentation of the 1980’s, innovations in low coherence interferometry for optical ranging and imaging for biomedical applications in the U.S., Europe and Japan by the early 1990’s led to coinage of the now widely known term OCT in 1991 [1]. As discussed in the following cited Invited Review and Invited Research articles in this issue, remarkable strides have since been made ...

      Read Full Article
    10. Multi-contrast imaging of human posterior eye by Jones matrix optical coherence tomography

      Multi-contrast imaging of human posterior eye by Jones matrix optical coherence tomography

      A multi-contrast imaging of pathologic posterior eyes is demonstrated by Jones matrix optical coherence tomography (Jones matrix OCT). The Jones matrix OCT provides five tomographies, which includes scattering, local attenuation, birefringence, polarization uniformity, and optical coherence angiography, by a single scan. The hardware configuration, algorithms of the Jones matrix OCT as well as its application to ophthalmology is discussed.

      Read Full Article
    11. Noise-bias and polarization-artifact corrected optical coherence tomography by maximum a-posteriori intensity estimation

      Noise-bias and polarization-artifact corrected optical coherence tomography by maximum a-posteriori intensity estimation

      We propose using maximum a-posteriori (MAP) estimation to improve the image signal-to-noise ratio (SNR) in polarization diversity (PD) optical coherence tomography. PD-detection removes polarization artifacts, which are common when imaging highly birefringent tissue or when using a flexible fiber catheter. However, dividing the probe power to two polarization detection channels inevitably reduces the SNR. Applying MAP estimation to PD-OCT allows for the removal of polarization artifacts while maintaining and improving image SNR. The effectiveness of the MAP-PD method is evaluated by comparing it with MAP-non-PD, intensity averaged PD, and intensity averaged non-PD methods. Evaluation was conducted in vivo with human ...

      Read Full Article
    12. Three-dimensional eye motion correction by Lissajous scan optical coherence tomography

      Three-dimensional eye motion correction by Lissajous scan optical coherence tomography

      A three-dimensional optical coherence tomography imaging method based on Lissajous scanning is presented. This method was designed to correct eye motion in OCT images. A Lissajous scanning pattern, which has a trajectory that frequently overlaps with itself, is adopted as the OCT scanning protocol to obtain measurement data. Eye motion artifacts are then corrected automatically by software. By comparing the images without and with motion correction, we show the effectiveness of our method. We performed an experiment and compared the results obtained by our method with the ground truths to verify its validity. The experimental results showed that our method ...

      Read Full Article
    13. Polarization sensitive optical coherence tomography – a review [Invited]

      Polarization sensitive optical coherence tomography – a review [Invited]

      Optical coherence tomography (OCT) is now a well-established modality for high-resolution cross-sectional and three-dimensional imaging of transparent and translucent samples and tissues. Conventional, intensity based OCT, however, does not provide a tissue-specific contrast, causing an ambiguity with image interpretation in several cases. Polarization sensitive (PS) OCT draws advantage from the fact that several materials and tissues can change the light’s polarization state, adding an additional contrast channel and providing quantitative information. In this paper, we review basic and advanced methods of PS-OCT and demonstrate its use in selected biomedical applications.

      Read Full Article
    14. High contrast and polarization-artifact-free optical coherence tomography by maximum a-posteriori estimation

      High contrast and polarization-artifact-free optical coherence tomography by maximum a-posteriori estimation

      We propose a maximum a-posteriori (MAP) intensity estimator to improve the image contrast of polarization diversity (PD)-OCT imaging to achieve high contrast polarization-artifact-free images. The MAP estimator compensates for the inevitable reduction of signal-to-noise ratio (SNR) in PD-OCT caused by the splitting of power into two polarization detection channels. It also has low noise-offset in low intensity regions such as the vitreous. This method is applied to posterior eye images, and shows high-contrast, polarization-artifact-free images. This method also enables attenuation coefficient imaging with finer differentiation of attenuation levels.

      Read Full Article
    15. Birefringence and vascular imaging of in vivo human skin by Jones-matrix optical coherence tomography

      Birefringence and vascular imaging of in vivo human skin by Jones-matrix optical coherence tomography

      A customized 1310-nm Jones-matrix optical coherence tomography (JM-OCT) for dermatological investigation was constructed and used for in vivo normal human skin tissue imaging. This system can simultaneously measure the threedimensional depth-resolved local birefringence, complex-correlation based OCT angiography (OCT-A), degree-ofpolarization- uniformity (DOPU) and scattering OCT intensity. By obtaining these optical properties of tissue, the morphology, vasculature, and collagen content of skin can be deduced and visualized. Structures in the deep layers of the epithelium were observed with depth-resolved local birefringence and polarization uniformity images. These results suggest high diagnostic and investigative potential of JM-OCT for dermatology.

      Read Full Article
    16. Motion-corrected en face optical coherence tomography angiography imaging based on the modified Lissajous scanning pattern

      Motion-corrected en face optical coherence tomography angiography imaging based on the modified Lissajous scanning pattern

      A motion - corrected en face optical coherence tomography angiography (OCT - A) imaging method is presented in this paper. This method was designed to correct eye motion artifacts in en face OCT - A images automatically using a software. A modified Lissajous scanning pattern, which is compatible with OCT - A, was adopted as the scanning protocol for the optical coherence tomography (OCT) machine to obtain the OCT - A data. The OCT - A data was then processed using motion correction algorithm that was tailored for the modified Lissajous scanning pattern to correct the eye motion artifacts in the en face plane. The OCT ...

      Read Full Article
    17. Three-dimensional multi-contrast imaging of in vivo human skin by Jones matrix optical coherence tomography

      Three-dimensional multi-contrast imaging of in vivo human skin by Jones matrix optical coherence tomography

      A custom made dermatological Jones matrix optical coherence tomography (JM-OCT) is presented. It uses a passive-polarization-delay component based swept-source JM-OCT configuration, but is specially designed for in vivo human skin measurement. The center wavelength of its probe beam is 1310 nm and the A-line rate is 49.6 kHz. The JM-OCT is capable of simultaneously providing birefringence (local retardation) tomography, degree-of-polarization-uniformity tomography, complex-correlation-based optical coherence angiography, and conventional scattering OCT. To evaluate the performance of this JM-OCT, we measured in vivo human skin at several locations. Using the four kinds of OCT contrasts, the morphological characteristics and optical properties of ...

      Read Full Article
    18. Noise stochastic corrected maximum a posteriori estimator for birefringence imaging using polarization-sensitive optical coherence tomography

      Noise stochastic corrected maximum a posteriori estimator for birefringence imaging using polarization-sensitive optical coherence tomography

      This paper presents a noise-stochastic corrected maximum a posteriori estimator for birefringence imaging using Jones matrix optical coherence tomography. The estimator described in this paper is based on the relationship between probability distribution functions of the measured birefringence and the effective signal to noise ratio (ESNR) as well as the true birefringence and the true ESNR. The Monte Carlo method is used to numerically describe this relationship and adaptive 2D kernel density estimation provides the likelihood for a posteriori estimation of the true birefringence. Improved estimation is shown for the new estimator with stochastic model of ESNR in comparison to ...

      Read Full Article
    19. Full-range ultrahigh-resolution spectral-domain optical coherence tomography in 1.7 µm wavelength region for deep-penetration and high-resolution imaging of turbid tissues

      Full-range ultrahigh-resolution spectral-domain optical coherence tomography in 1.7 µm wavelength region for deep-penetration and high-resolution imaging of turbid tissues

      For the first time, we developed a full-range ultrahigh-resolution (UHR) spectral-domain optical coherence tomography (SD-OCT) technique working in the 1.7 µm wavelength region. This technique allowed high-resolution, deep-tissue imaging. By using a supercontinuum source operating at a wavelength of 1.7 µm, an axial resolution of 3.6 µm in a tissue specimen was achieved. To enhance the imaging depth of UHR-SD-OCT, we performed full-range OCT imaging based on a phase modulation method. We demonstrated the three-dimensional (3D) imaging of a mouse brain with the developed system, and specific structures in the mouse brain were clearly visualized at depths ...

      Read Full Article
    20. Quantitative Evaluation of Phase Retardation in Filtering Blebs Using Polarization-Sensitive Optical Coherence Tomography

      Quantitative Evaluation of Phase Retardation in Filtering Blebs Using Polarization-Sensitive Optical Coherence Tomography

      Purpose : Polarization-sensitive optical coherence tomography (PS-OCT) can detect and evaluate scar fibrosis of the filtering blebs after glaucoma surgery. Although the change in phase retardation reportedly reflects bleb function, quantitative assessment of phase retardation in ocular tissues has not been conducted. We aimed to establish quantitative methods to investigate changes in phase retardation in the blebs after surgery using PS-OCT. Methods : Twenty-two blebs of 22 patients who had undergone glaucoma filtration surgery were consecutively examined for 4 months. Phase retardation was measured by PS-OCT and quantitatively analyzed to evaluate its relationship with bleb function based on intraocular pressure and medication ...

      Read Full Article
    21. Investigation of Thermal Effects of Photocoagulation on Retinal Tissue Using Fine-Motion-Sensitive Dynamic Optical Coherence Tomography

      Investigation of Thermal Effects of Photocoagulation on Retinal Tissue Using Fine-Motion-Sensitive Dynamic Optical Coherence Tomography

      To enable an objective evaluation of photocoagulation, we characterize thermal tissue changes induced by laser irradiation with different laser parameters using optical coherence tomography (OCT). Spectral-domain OCT with a newly developed image processing method was used to monitor the thermal changes of ex vivo porcine retina. A sequence of OCT B-scans was obtained at the same retinal position simultaneously with the photocoagulation. Cross-sectional tissue displacement maps with respect to an OCT image taken before laser irradiation were computed for images taken before, during, and after laser irradiation, by using a correlation-based custom algorithm. Cross-sectional correlation maps (OCT correlation maps) were ...

      Read Full Article
    22. Objective Evaluation of Functionality of Filtering Bleb Based on Polarization-Sensitive Optical Coherence Tomography

      Objective Evaluation of Functionality of Filtering Bleb Based on Polarization-Sensitive Optical Coherence Tomography

      Purpose : The fibrosis score is a new diagnostic score that we have developed to evaluate the function of bleb structures after glaucoma filtration surgery using polarization-sensitive optical coherence tomography (PS-OCT). This study aims to assess the efficacy of the fibrosis score in discriminating nonfunctional from the functional blebs. Methods : A total of 20 patients who had undergone glaucoma filtration surgery were imaged at different time periods after surgery using PS-OCT. Birefringence tomography of blebs was obtained from PS-OCT, and the fibrosis score was computed for each patient. The fibrosis score is defined as the area of occupation of high birefringence ...

      Read Full Article
    23. Eye motion corrected OCT imaging with Lissajous scan pattern

      Eye motion corrected OCT imaging with Lissajous scan pattern

      Ophthalmic optical coherence tomography (OCT) is a powerful tool which provides high resolution three dimensional (3D) volumetric image of human retina. However, the measurement data of OCT suffer motion artifact due to the involuntary eye motion during data acquisition. To eliminate this motion artifact and provide the true shape of retinal image, an eye motion corrected OCT imaging method based on Lissajous scan pattern is proposed in this paper. In this approach, we adopted Lissajous scan pattern for 3D-OCT imaging and developed motion correction algorithm. To verify the effectiveness of this method, we compare our method with single raster scan ...

      Read Full Article
    24. Quantitative optical coherence tomography by maximum a-posteriori estimation of signal intensity

      Quantitative optical coherence tomography by maximum a-posteriori estimation of signal intensity

      A maximum a-posteriori (MAP) estimator for signal amplitude of optical coherence tomography (OCT) is presented. This estimator provides an accurate and low bias estimation of the correct OCT signal amplitude even at very low signal-tonoise ratios. As a result, contrast improvement of retinal OCT images is demonstrated. In addition, this estimation method allows for an estimation reliability to be calculated. By combining the MAP estimator with a previously demonstrated attenuation imaging algorithm, we present attenuation coefficient images of the retina. From the reliability derived from the MAP image one can also determine which regions of the attenuation images are unreliable ...

      Read Full Article
    1-24 of 134 1 2 3 4 5 6 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Topics in the News

    1. (133 articles) Yoshiaki Yasuno
    2. (130 articles) University of Tsukuba
    3. (82 articles) Shuichi Makita
    4. (44 articles) Masahiro Miura
    5. (41 articles) Masahiro Yamanari
    6. (24 articles) Tokyo Medical University
    7. (14 articles) Deepa K. Kasaragod
    8. (12 articles) Tapio E. J. Fabritius
    9. (11 articles) University of Oulu
    10. (8 articles) Hiroshi Goto
    11. (1 articles) Massachusetts Eye and Ear Infirmary
    12. (1 articles) Harvard University
    13. (1 articles) University of Kent
    14. (1 articles) Adrian G. Podoleanu
    15. (1 articles) Saba Adabi
    16. (1 articles) Seok-Hyun Yun
    17. (1 articles) Optovue
    18. (1 articles) Heidelberg Engineering
    19. (1 articles) Avinger
  3. Popular Articles

  4. Picture Gallery

    Automated segmentation of the macula by optical coherence tomography Tissue discrimination in anterior eye using three optical parameters obtainedby polarization sensitive optical coherence tomography Parabolic BM-scan technique for full range Doppler spectral domain optical coherence tomography Visibility of trabecular meshwork by standard and polarization-sensitive optical coherence tomography Reproducibility of Retinal and Choroidal Thickness Measurements in Enhanced Depth Imaging and High-Penetration Optical Coherence Tomography Repeatability, reproducibility and agreement of foveal avascular zone measurements using three different optical coherence tomography angiography devices Subclinical hypothyroidism is associated with lipid-rich plaques in patients with coronary artery disease as assessed by optical coherence tomography Mitigation of Speckle Noise in Optical Coherence Tomograms Mapping the phase and amplitude of ossicular chain motion using sound-synchronous optical coherence vibrography Avinger Receives CE Marking Approval for Pantheris SV, a New Image-Guided Atherectomy Device Designed to Treat Smaller Vessels Phenotyping of Mouse Models with OCT Effect of orbital atherectomy in calcified coronary artery lesions as assessed by optical coherence tomography