1. Articles from Shuichi Makita

    1-24 of 100 1 2 3 4 5 »
    1. Non-destructive characterization of adult zebrafish models using Jones matrix optical coherence tomography

      Non-destructive characterization of adult zebrafish models using Jones matrix optical coherence tomography

      The zebrafish is a valuable vertebrate animal model in pre-clinical cancer research. A Jones matrix optical coherence tomography (JM-OCT) prototype operating at 1310 nm and an intensity-based spectral-domain OCT setup at 840 nm were utilized to investigate adult wildtype and a tumor-developing zebrafish model. Various anatomical features were characterized based on their inherent scattering and polarization signature. A motorized translation stage in combination with the JM-OCT prototype enabled large field-of-view imaging to investigate adult zebrafish in a non-destructive way. The diseased animals exhibited tumor-related abnormalities in the brain and near the eye region. The scatter intensity, the attenuation coefficients and ...

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    2. Evaluation of choroidal melanin-containing tissue in healthy Japanese subjects by polarization-sensitive optical coherence tomography

      Evaluation of choroidal melanin-containing tissue in healthy Japanese subjects by polarization-sensitive optical coherence tomography

      In this study, the choroidal melanin content in healthy eyes was evaluated with polarization-sensitive optical coherence tomography (PS-OCT). We evaluated 105 healthy eyes of 105 Japanese subjects. The mean thickness of melanin-containing tissue in the choroid (thickness of MeCh) and the choroidal melanin occupancy rate within a 5-mm circular region from the foveal center were calculated using the degree of polarization uniformity obtained by PS-OCT and compared with the choroidal thickness, patient age, and axial length. To evaluate regional variations, the 5-mm circular region was divided into a center area and an outer ring area, and the outer ring area ...

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    3. Objective evaluation of choroidal melanin loss in patients with Vogt–Koyanagi–Harada disease using polarization-sensitive optical coherence tomography

      Objective evaluation of choroidal melanin loss in patients with Vogt–Koyanagi–Harada disease using polarization-sensitive optical coherence tomography

      In this study, sunset glow fundus was evaluated in patients with Vogt-Koyanagi-Harada (VKH) disease using polarization-sensitive optical coherence tomography (PS-OCT). We evaluated 40 VKH eyes (20 patients) and 59 healthy eyes (59 age-matched controls). VKH eyes were divided into three groups according to color fundus images: sunset (17 eyes), potential sunset (13 eyes), and non-sunset (10 eyes). Choroidal melanin thickness (ChMeT) and the choroidal melanin thickness ratio (ChMeTratio) were calculated based on the degree of polarization uniformity from PS-OCT. ChMeT was significantly lower in sunset eyes than in non-sunset or control eyes (P = 0.003). The ChMeTratios of sunset or ...

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    4. Deep convolutional neural network-based scatterer density and resolution estimators in optical coherence tomography

      Deep convolutional neural network-based scatterer density and resolution estimators in optical coherence tomography

      We present deep convolutional neural network (DCNN)-based estimators of the tissue scatterer density (SD), lateral and axial resolutions, signal-to-noise ratio (SNR), and effective number of scatterers (ENS, the number of scatterers within a resolution volume). The estimators analyze the speckle pattern of an optical coherence tomography (OCT) image in estimating these parameters. The DCNN is trained by a large number (1,280,000) of image patches that are fully numerically generated in OCT imaging simulation. Numerical and experimental validations were performed. The numerical validation shows good estimation accuracy as the root mean square errors were 0.23%, 3.65 ...

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    5. Three-dimensional dynamics optical coherence tomography for tumor spheroid evaluation

      Three-dimensional dynamics optical coherence tomography for tumor spheroid evaluation

      We present a completely label-free three-dimensional (3D) optical coherence tomography (OCT)-based tissue dynamics imaging method for visualization and quantification of the metabolic and necrotic activities of tumor spheroid. Our method is based on a custom 3D scanning protocol that is designed to capture volumetric tissue dynamics tomography images only in a few tens of seconds. The method was applied to the evaluation of a tumor spheroid. The time-course viability alteration and anti-cancer drug response of the spheroid were visualized qualitatively and analyzed quantitatively. The similarity between the OCT-based dynamics images and fluorescence microscope images was also demonstrated.

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    6. Label-free functional and structural imaging of liver microvascular complex in mice by Jones matrix optical coherence tomography

      Label-free functional and structural imaging of liver microvascular complex in mice by Jones matrix optical coherence tomography

      We demonstrate label-free imaging of the functional and structural properties of microvascular complex in mice liver. The imaging was performed by a custom-built Jones-matrix based polarization sensitive optical coherence tomography (JM-OCT), which is capable of measuring tissue's attenuation coefficient, birefringence, and tiny tissue dynamics. Two longitudinal studies comprising a healthy liver and an early fibrotic liver model were performed. In the healthy liver, we observed distinctive high dynamics beneath the vessel at the initial time point (0 h) and reappearance of high dynamics at 32-h time point. In the early fibrotic liver model, we observed high dynamics signal that ...

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    7. Computational multi-directional optical coherence tomography for visualizing the microstructural directionality of the tissue

      Computational multi-directional optical coherence tomography for visualizing the microstructural directionality of the tissue

      We demonstrate computational multi-directional optical coherence tomography (OCT) to assess the directional property of tissue microstructure. This method is the combination of phase-sensitive volumetric OCT imaging and post-signal processing. The latter comprises of two steps. The first step is an intensity-directional analysis, which determines the dominant en face fiber orientations. The second step is the phase-directional imaging, which reveals the sub-resolution depth-orientation of the microstructure. The feasibility of the method was tested by assessing muscle and tendon samples. Stripe patterns with several sizes were visualized in the phase-directional images. In order to interpret these images, the muscle and tendon structures ...

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    8. Accurately motion-corrected Lissajous OCT with multi-type image registration

      Accurately motion-corrected Lissajous OCT with multi-type image registration

      Passive motion correction methods for optical coherence tomography (OCT) use image registration to estimate eye movements. To improve motion correction, a multi-image cross-correlation that employs spatial features in different image types is introduced. Lateral motion correction using en face OCT and OCT-A projections on Lissajous-scanned OCT data is applied. Motion correction using OCT-A projection of whole depth and OCT amplitude, OCT logarithmic intensity, and OCT maximum intensity projections were evaluated in retinal imaging with 76 patients. The proposed method was compared with motion correction using OCT-A projection of whole depth. The comparison shows improvements in the image quality of motion-corrected ...

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    9. Optical coherence tomography-based tissue dynamics imaging for longitudinal and drug response evaluation of tumor spheroids

      Optical coherence tomography-based tissue dynamics imaging for longitudinal and drug response evaluation of tumor spheroids

      We present optical coherence tomography (OCT)-based tissue dynamics imaging method to visualize and quantify tissue dynamics such as subcellular motion based on statistical analysis of rapid-time-sequence OCT signals at the same location. The analyses include logarithmic intensity variance (LIV) method and two types of OCT correlation decay speed analysis (OCDS). LIV is sensitive to the magnitude of the signal fluctuations, while OCDSs including early- and late-OCDS (OCDS e and OCDS l , respectively) are sensitive to the fast and slow tissue dynamics, respectively. These methods were able to visualize and quantify the longitudinal necrotic process of a human breast adenocarcinoma ...

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    10. Quantitative multi-contrast in vivo mouse imaging with polarization diversity optical coherence tomography and angiography

      Quantitative multi-contrast in vivo mouse imaging with polarization diversity optical coherence tomography and angiography

      Retinal microvasculature and the retinal pigment epithelium (RPE) play vital roles in maintaining the health and metabolic activity of the eye. Visualization of these retina structures is essential for pre-clinical studies of vision-robbing diseases, such as age-related macular degeneration (AMD). We have developed a quantitative multi-contrast polarization diversity OCT and angiography (QMC-PD-OCTA) system for imaging and visualizing pigment in the RPE using degree of polarization uniformity (DOPU), along with flow in the retinal capillaries using OCT angiography (OCTA). An adaptive DOPU averaging kernel was developed to increase quantifiable values from visual data, and QMC en face images permit simultaneous visualization ...

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    11. Depth‐resolved investigation of multiple optical properties and wrinkle morphology in eye‐corner areas with multi‐contrast Jones matrix optical coherence tomography

      Depth‐resolved investigation of multiple optical properties and wrinkle morphology in eye‐corner areas with multi‐contrast Jones matrix optical coherence tomography

      Background Multi‐contrast Jones matrix optical coherence tomography (JM‐OCT) can provide quantitative depth‐resolved local optical properties by improving the measurement algorithm. Materials and methods We examined the relationship between depth‐resolved local optical properties of eye‐corner skin measured by JM‐OCT and corresponding wrinkle morphology of aged women (n = 21; age range, 71.7 ± 1.7 years). Wrinkle morphology was analyzed by measuring the surface topography of three‐dimensional replicas. The same regions were measured three‐dimensionally by JM‐OCT, and the local optical properties at each depth were computed. Results Birefringence (BR) and mean wrinkle depth ...

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    12. Depth-resolved investigation of multiple optical properties and wrinkle morphology in eye-corner areas with multi-contrast Jones matrix optical coherence tomography

      Depth-resolved investigation of multiple optical properties and wrinkle morphology in eye-corner areas with multi-contrast Jones matrix optical coherence tomography

      Background: Multi-contrast Jones matrix optical coherence tomography (JM-OCT) can provide quantitative depth-resolved local optical properties by improving the measurement algorithm. Materials and methods: We examined the relationship between depth-resolved local optical properties of eye-corner skin measured by JM-OCT and corresponding wrinkle morphology of aged women (n = 21; age range, 71.7 ± 1.7 years). Wrinkle morphology was analyzed by measuring the surface topography of three-dimensional replicas. The same regions were measured three-dimensionally by JM-OCT, and the local optical properties at each depth were computed. Results: Birefringence (BR) and mean wrinkle depth correlated significantly at a depth of 88.2-138.6 ...

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    13. Bulk-phase-error correction for phase-sensitive signal processing of optical coherence tomography

      Bulk-phase-error correction for phase-sensitive signal processing of optical coherence tomography

      We present a numerical phase stabilization method for phase-sensitive signal processing of optical coherence tomography (OCT). This method removes the bulk phase error caused by the axial bulk motion of the sample and the environmental perturbation during volumetric acquisition. In this method, the partial derivatives of the phase error are computed along both fast and slow scanning directions, so that the vectorial gradient field of the phase error is given. Then, the phase error is estimated from the vectorial gradient field by a newly developed line integration method; a smart integration path method. The performance of this method was evaluated ...

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    14. Polarization-sensitive optical coherence elastography

      Polarization-sensitive optical coherence elastography

      Polarization-sensitive optical coherence elastography (PS-OCE) is developed for improved tissue discrimination. It integrates Jones matrix-based PS-optical coherence tomography (PS-OCT) with compression OCE. The method simultaneously measures the OCT intensity, attenuation coefficient, birefringence, and microstructural deformation (MSD) induced by tissue compression. Ex vivo porcine aorta and esophagus tissues were investigated by PS-OCE and histological imaging. The tissue properties measured by PS-OCE are shown as cross-sectional images and a three-dimensional (3-D) depth-trajectory plot. In this trajectory plot, the average attenuation coefficient, birefringence, and MSD were computed at each depth, and the trajectory in the depth direction was plotted in a 3-D feature ...

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    15. Evaluation of Retinal Pigment Epithelium Layer Change in Vogt-Koyanagi-Harada Disease With Multicontrast Optical Coherence Tomography

      Evaluation of Retinal Pigment Epithelium Layer Change in Vogt-Koyanagi-Harada Disease With Multicontrast Optical Coherence Tomography

      Purpose : Clinical evaluation of retinal pigment epithelium (RPE) change is important for the therapeutic management of chronic Vogt-Koyanagi-Harada (VKH) disease. We evaluated long-term change in the RPE layer in VKH disease, using near-infrared (NIR; 817 nm) images and autofluorescence images at 488 nm (short-wavelength [SW]-AF) and 785 nm (NIR-AF), and compared those images with images from multicontrast optical coherence tomography (MC-OCT). MC-OCT is capable of simultaneous measurement of OCT angiography, polarization-sensitive OCT, and standard OCT. Methods : We evaluated 24 eyes of 12 patients with chronic VKH disease. RPE changes were assessed using NIR, NIR-AF, SW-AF, and MC-OCT imaging performed ...

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    16. Multi-scale and -contrast sensorless adaptive optics optical coherence tomography

      Multi-scale and -contrast sensorless adaptive optics optical coherence tomography

      Background: The roles of the retinal microvasculature and the retinal pigment epithelium (RPE) in maintaining the health and metabolic activity of the retina lend great clinical value to their high-resolution visualization. Methods: By integrating polarization diversity detection (PDD) into multi-scale and -contrast sensorless adaptive optics optical coherence tomography (MSC-SAO-OCT), we have developed a novel multi-contrast SAO OCT system for imaging pigment in the RPE as well as flow in the retinal capillaries using OCT angiography (OCTA). Aberration correction was performed based on the image quality using transmissive deformable optical elements. Results: MSC-SAO-OCTA imaging was performed at multiple fields-of-view (FOVs) with ...

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    17. 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 ...

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    18. 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 ...

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    19. 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 ...

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    20. 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 ...

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    21. 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.

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    22. 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 ...

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    23. 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 ...

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    24. 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 ...

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