1. Articles from Dan Zhu

    1-11 of 11
    1. Macular and Optic Disc Parameters in Children with Amblyopic and Nonamblyopic Eyes under Optical Coherence Tomography Fundus Images

      Macular and Optic Disc Parameters in Children with Amblyopic and Nonamblyopic Eyes under Optical Coherence Tomography Fundus Images

      The aim of this study was to investigate the characteristics of macular and optic disc parameters in children with amblyopic and nonamblyopic eyes, using fundus images under optical coherence tomography (OCT). 36 patients with anisometropic amblyopia were selected in the experimental group, and another 36 healthy volunteers were selected in the control group, OCT examinations were performed in all groups, and the mean diopter, mean corrected visual acuity (CVA), mean axial length, mean optic disc retinal nerve fiber layer (RNFL) thickness, and mean macular fovea thickness were recorded in the two groups. The results found that the average diopter of ...

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    2. Differentiation of breast tissue types for surgical margin assessment using machine learning and polarization-sensitive optical coherence tomography

      Differentiation of breast tissue types for surgical margin assessment using machine learning and polarization-sensitive optical coherence tomography

      We report an automated differentiation model for classifying malignant tumor, fibro-adipose, and stroma in human breast tissues based on polarization-sensitive optical coherence tomography (PS-OCT). A total of 720 PS-OCT images from 72 sites of 41 patients with H&E histology-confirmed diagnoses as the gold standard were employed in this study. The differentiation model is trained by the features extracted from both one standard OCT-based metric (i.e., intensity) and four PS-OCT-based metrics (i.e., phase difference between two channels ( PD ), phase retardation ( PR ), local phase retardation ( LPR ), and degree of polarization uniformity ( DOPU )). Further optimized by forward searching and validated ...

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    3. Automated fast computational adaptive optics for optical coherence tomography based on a stochastic parallel gradient descent algorithm

      Automated fast computational adaptive optics for optical coherence tomography based on a stochastic parallel gradient descent algorithm

      The transverse resolution of optical coherence tomography is decreased by aberrations introduced from optical components and the tested samples. In this paper, an automated fast computational aberration correction method based on a stochastic parallel gradient descent (SPGD) algorithm is proposed for aberration-corrected imaging without adopting extra adaptive optics hardware components. A virtual phase filter constructed through combination of Zernike polynomials is adopted to eliminate the wavefront aberration, and their coefficients are stochastically estimated in parallel through the optimization of the image metrics. The feasibility of the proposed method is validated by a simulated resolution target image, in which the introduced ...

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    4. Recent progress in optical probing and manipulation of tissue: introduction

      Recent progress in optical probing and manipulation of tissue: introduction

      This feature issue of Biomedical Optics Express represents a cross-section of the most recent work in tissue optics, including exciting developments in tissue optical clearing, deep tissue imaging, optical elastography, nanophotonics in tissue, and therapeutic applications of light, amongst others. A collection of 33 papers provides a comprehensive overview of current research in tissue optics, much of it inspired and informed by the pioneering work of Prof. Valery Tuchin. The issue contains three invited manuscripts and several mini-reviews that we hope will benefit researchers in this exciting area.

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    5. Visualization of skin microvascular dysfunction of type 1 diabetic mice using in vivo skin optical clearing method

      Visualization of skin microvascular dysfunction of type 1 diabetic mice using in vivo skin optical clearing method

      To realize visualization of the skin microvascular dysfunction of type 1 diabetic mice, we combined laser speckle contrast imaging and hyperspectral imaging to simultaneously monitor the noradrenaline (NE)-induced responses of vascular blood flow and blood oxygen with the development of diabetes through optical clearing skin window. The main results showed that venous and arterious blood flow decreased without recovery after injection of NE; furthermore, the decrease of arterious blood oxygen induced by NE greatly weakened, especially for 2- and 4-week diabetic mice. This change in vasoconstricting effect of NE was related to the expression of α1-adrenergic receptor. This study ...

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    6. A useful way to develop effective in vivo skin optical clearing agents

      A useful way to develop effective in vivo skin optical clearing agents

      Skin optical clearing has shown tremendous potential in improving various optical imaging performances, but there is some certain blindness in screening out high-efficiency in vivo optical clearing methods. In this work, three optical clearing agents: sucrose (Suc), fructose (Fruc) and PEG-400 (PEG), and two chemical penetration enhancers: propylene glycol (PG) and thiazone (Thiaz) were used. PEG was firstly mixed with the two penetration enhancers, respectively, and then mixed with Fruc and Suc, respectively, to obtain six kinds of skin optical clearing agents (SOCAs). Optical coherence tomography angiography was applied to monitor SOCAs-induced changes in imaging performances, skin optical properties, refractive ...

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    7. Optical coherence tomography angiography offers comprehensive evaluation of skin optical clearing in vivo by quantifying optical properties and blood flow imaging simultaneously

      Optical coherence tomography angiography offers comprehensive evaluation of skin optical clearing in vivo by quantifying optical properties and blood flow imaging simultaneously

      Tissue optical clearing (TOC) is helpful for reducing scattering and enhancing the penetration depth of light, and shows promising potential in optimizing optical imaging performances. A mixture of fructose with PEG-400 and thiazone (FPT) is used as an optical clearing agent in mouse dorsal skin and evaluated with OCT angiography (Angio-OCT) by quantifying optical properties and blood flow imaging simultaneously. It is observed that FPT leads to an improved imaging performance for the deeper tissues. The imaging performance improvement is most likely caused by the FPT-induced dehydration of skin, and the reduction of scattering coefficient (more than ∼ 40.5 % ∼40 ...

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    8. Alignment analyses of a galvanometer-based scanner in free-space Fourier domain optical coherence tomography

      Alignment analyses of a galvanometer-based scanner in free-space Fourier domain optical coherence tomography

      Free-space Fourier domain optical coherence tomography is adopted for biomedical imaging with ultrahigh resolution, in which the setup consists of an interferometer and a spectrometer. Two-dimensional lateral sampling in the sample arm of the interferometer is achieved by using a galvanometer-based scanner. Optical path difference (OPD) drift in the full scan field of view is observed in the assembly process of the scanner. A galvo mirror mount offset with respect to the rotation axis is demonstrated as the derivation of this OPD drift by both geometric analyses and model building. Then, an iterative assembly process of the scanner is proposed ...

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    9. Switchable skin window induced by optical clearing method for dermal blood flow imaging

      Switchable skin window induced by optical clearing method for dermal blood flow imaging

       Optical imaging techniques have shown tremendous potential for assessing cutaneous microcirculation, but the imaging depth and contrast is limited by the strong scattering of skin. Current skin windows have to be fulfilled by surgical operation and suffer from some side effects. In this study, a switchable skin window was developed by topical application of an optical clearing agent (OCA) and saline on rat skin in vivo. The validity of the skin window was evaluated by the laser speckle contrast imaging technique, and the safety of OCA to the body was tested through histologic examinations. The results indicated that administration of ...

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    10. Feature Of The Week 07/01/12: Enhanced Optical Clearing of Skin In Vivo and OCT In-Depth Imaging

      Feature Of The Week 07/01/12: Enhanced Optical Clearing of Skin In Vivo and OCT In-Depth Imaging

      Imaging methods such as optical coherence tomography (OCT), confocal reflectance/ fluorescence microscopy, second-harmonic generation microscopy, and 2-photon microscopy are limited by the optical scattering properties of the skin to superficial depths. Optical clearing technique using high refractive index and hyperosmolarity agents can reduce the scattering of biological tissues. With this approach, better optical imaging depth and contrast have been presented and deeper optical treatment has been achieved. However, noninvasive optical clearing of skin in vivo is difficult, because the outermost layer of the skin, the stratum corneum, presents a significant barrier to topically applied OCAs. In this work, OCT imaging ...

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    11. Enhanced optical clearing of skin in vivo and optical coherence tomography in-depth imaging

      Enhanced optical clearing of skin in vivo and optical coherence tomography in-depth imaging

      The strong optical scattering of skin tissue makes it very difficult for optical coherence tomography (OCT) to achieve deep imaging in skin. Significant optical clearing of in vivo rat skin sites was achieved within 15 min by topical application of an optical clearing agent PEG-400, a chemical enhancer (thiazone or propanediol), and physical massage. Only when all three components were applied together could a 15 min treatment achieve a three fold increase in the OCT reflectance from a 300 μm depth and 31% enhancement in image depth Zthreshold.

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    1-11 of 11
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    1. (2 articles) University of Oulu
    2. (2 articles) University of Illinois at Urbana-Champaign
    3. (2 articles) Oregon Health & Science University
    4. (2 articles) Zhejiang University
    5. (2 articles) Thorlabs
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    Enhanced optical clearing of skin in vivo and optical coherence tomography in-depth imaging Feature Of The Week 07/01/12: Enhanced Optical Clearing of Skin In Vivo and OCT In-Depth Imaging Switchable skin window induced by optical clearing method for dermal blood flow imaging Alignment analyses of a galvanometer-based scanner in free-space Fourier domain optical coherence tomography Optical coherence tomography angiography offers comprehensive evaluation of skin optical clearing in vivo by quantifying optical properties and blood flow imaging simultaneously A useful way to develop effective in vivo skin optical clearing agents Visualization of skin microvascular dysfunction of type 1 diabetic mice using in vivo skin optical clearing method Recent progress in optical probing and manipulation of tissue: introduction Automated fast computational adaptive optics for optical coherence tomography based on a stochastic parallel gradient descent algorithm Differentiation of breast tissue types for surgical margin assessment using machine learning and polarization-sensitive optical coherence tomography Influence of scan direction on subfoveal choroidal vascularity index using optical coherence tomography Subthreshold Nanosecond Laser for Non-resolving Central Serous Chorioretinopathy: A Double-masked Sham-controlled Randomised Trial