1. Articles from Qiushi Ren

    1-19 of 19
    1. Weakly Supervised Deep Learning Based Optical Coherence Tomography Angiography

      Weakly Supervised Deep Learning Based Optical Coherence Tomography Angiography

      Optical coherence tomography angiography (OCTA) is a promising imaging modality for microvasculature studies. Deep learning networks have been widely applied in the field of OCTA reconstruction, benefiting from its powerful mapping capability among images. However, these existing deep learning-based methods depend on high-quality labels, which are hard to acquire considering imaging hardware limitations and practical data acquisition conditions. In this paper, we proposed an unprecedented weakly supervised deep learning-based pipeline for OCTA reconstruction task, in the absence of high-quality training labels. The proposed pipeline was investigated on an in vivo animal dataset and a human eye dataset by a cross-validation ...

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    2. N2NSR‐OCT: Simultaneous denoising and super‐resolution in optical coherence tomography images using semi‐supervised deep learning

      N2NSR‐OCT: Simultaneous denoising and super‐resolution in optical coherence tomography images using semi‐supervised deep learning

      Optical coherence tomography (OCT) imaging shows a significant potential in clinical routines due to its noninvasive property. However, the quality of OCT images is generally limited by inherent speckle noise of OCT imaging and low sampling rate. To obtain high signal‐to‐noise ratio (SNR) and high‐resolution (HR) OCT images within a short scanning time, we presented a learning‐based method to recover high‐quality OCT images from noisy and low‐resolution OCT images. We proposed a semi‐supervised learning approach named N2NSR‐OCT, to generate denoised and super‐resolved OCT images simultaneously using up‐ and down‐sampling networks ...

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    3. Retinal choroidal vessel imaging based on multi-wavelength fundus imaging with the guidance of optical coherence tomography

      Retinal choroidal vessel imaging based on multi-wavelength fundus imaging with the guidance of optical coherence tomography

      A multispectral fundus camera (MSFC), as a novel noninvasive technology, uses an extensive range of monochromatic light sources that enable the view of different sectional planes of the retinal and choroidal structures. However, MSFC imaging involves complex processes affected by various factors, and the recognized theory based on light absorption above the choroid is not sufficient. In an attempt to supplement the relevant explanations, in this study, we used optical coherence tomography (OCT), a three-dimensional tomography modality, to analyze MSFC results at the retina and choroid. The swept-source OCT system at 1060 nm wavelength with a 200 kHz A-scan rate ...

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    4. Comparative study of deep learning models for optical coherence tomography angiography

      Comparative study of deep learning models for optical coherence tomography angiography

      Optical coherence tomography angiography (OCTA) is a promising imaging modality for microvasculature studies. Meanwhile, deep learning has achieved rapid development in image-to-image translation tasks. Some studies have proposed applying deep learning models to OCTA reconstruction and have obtained preliminary results. However, current studies are mostly limited to a few specific deep neural networks. In this paper, we conducted a comparative study to investigate OCTA reconstruction using deep learning models. Four representative network architectures including single-path models, U-shaped models, generative adversarial network (GAN)-based models and multi-path models were investigated on a dataset of OCTA images acquired from rat brains. Three ...

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    5. Noise reduction in optical coherence tomography images using a deep neural network with perceptually-sensitive loss function

      Noise reduction in optical coherence tomography images using a deep neural network with perceptually-sensitive loss function

      Optical coherence tomography (OCT) is susceptible to the coherent noise, which is the speckle noise that deteriorates contrast and the detail structural information of OCT images, thus imposing significant limitations on the diagnostic capability of OCT. In this paper, we propose a novel OCT image denoising method by using an end-to-end deep learning network with a perceptually-sensitive loss function. The method has been validated on OCT images acquired from healthy volunteers’ eyes. The label images for training and evaluating OCT denoising deep learning models are images generated by averaging 50 frames of respective registered B-scans acquired from a region with ...

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    6. Adaptive classifier allows enhanced flow contrast in OCT angiography using a histogram-based motion threshold and 3D Hessian analysis-based shape filtering

      Adaptive classifier allows enhanced flow contrast in OCT angiography using a histogram-based motion threshold and 3D Hessian analysis-based shape filtering

      In this Letter, we propose an adaptive digital classifier for flow contrast enhancement in optical coherence tomography angiography (OCTA). To solve the depth dependence in the initial motion-based classification, a depth-adaptive motion threshold was determined by performing a histogram analysis of an en-face image at each depth and identifying the static and dynamic voxel populations through fitting. In the follow-up shape-based classification, to adapt to the deformed vessel shapes in OCTA, a modified vesselness function along with an anisotropic Gaussian probe kernel was defined, and then a three-dimensional (3D) Hessian analysis-based shape filtering was utilized for effectively removing the residual ...

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    7. Dual band dual focus optical coherence tomography for imaging the whole eye segment

      Dual band dual focus optical coherence tomography for imaging the whole eye segment

      We developed an improved dual band dual focus spectral domain optical coherence tomography (SD-OCT) for in vivo 2D/3D imaging of the whole eye segment, including the whole anterior segment and retina. The system featured two OCT channels with two different bands centered at 840 nm and 1050 nm, which were designed to image the retina and the anterior segments of the eye, respectively. By combing the two probe light beams for co-axial scanning and separating them for focusing at different segments of the eye with a combination of three dichroic mirrors, we not only minimized the loss of the ...

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    8. PEGylated Aucore–Agshell Nanorods as Optical Coherence Tomography Signal Nanoamplifiers

      PEGylated Aucore–Agshell Nanorods as Optical Coherence Tomography Signal Nanoamplifiers

      Optimizing contrast enhancement in optical coherence tomography (OCT) is essential for producing specific image signals and realizing its potential use in various biomedical imaging fields besides ophthalmology and cardiology. Using nanoparticles as selective signal nanoamplifiers will be helpful to highlight the lesion sites and identify cancerous changes that are difficult to diagnose currently. In this study, a quantitatively detailed analysis on the improvement of contrast enhancement and penetration depth of Au core –Ag shell nanorods (Au@Ag NRs) as OCT contrast agent was performed. The average A-scan data of the tissue was extracted and investigated. The signal to noise ratio ...

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    9. Whole Eye Segment Imaging and Measurement With Dual-Channel Spectral-Domain OCT

      Whole Eye Segment Imaging and Measurement With Dual-Channel Spectral-Domain OCT

      BACKGROUND AND OBJECTIVES: To image and measure whole eye segments using dual-channel spectral-domain optical coherence tomography (SD-OCT) and to compare the results with those from the IOLMaster (Carl Zeiss Meditec, Dublin, CA). PATIENTS AND METHODS: Twenty eyes of 20 volunteers were recruited. Ocular dimensions, including cornea thickness, anterior chamber depth (ACD), lens thickness, anterior lens surface curvature, and axial length (AL), were calculated. The reproducibility of SD-OCT measurements, statistical significance of inter-instrument difference, correlation, and agreement were evaluated. RESULTS: No significant differences were found between independent SD-OCT measurements ( P > .05). The ACD and AL measured with IOLMaster were significantly shorter ...

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    10. Accommodation-induced variations in retinal thickness measured by spectral domain optical coherence tomography

      Accommodation-induced variations in retinal thickness measured by spectral domain optical coherence tomography

      To research retinal stretching or distortion with accommodation, accommodation-induced changes in retinal thickness (RT) in the macular area were investigated in a population of young adults ( n = 23 ) by using a dual-channel spectral domain optical coherence tomography (SD-OCT) system manufactured in-house for this study. This dual-channel SD-OCT is capable of imaging the cornea and retina simultaneously with an imaging speed of 24 kHz A-line scan rate, which can provide the anatomical dimensions of the eye, including the RT and axial length. Thus, the modification of the RT with accommodation can be calculated. A significant decrease in the RT ( 13.50 ...

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    11. Dual-channel spectral-domain optical-coherence tomography system based on 3 × 3 fiber coupler for extended imaging range

      Dual-channel spectral-domain optical-coherence tomography system based on 3 × 3 fiber coupler for extended imaging range

      We have demonstrated a dual-channel multiplexing spectral-domain optical-coherence tomography (SD-OCT) system based on a 3 × 3 fiber coupler for extended imaging range of whole human eye depth, with a single light source and spectrometer. OCT images of anterior segments of a human eye were sequentially performed and constructed to demonstrate an extended depth range as large as 15 mm in air. A good quality OCT image of the whole anterior segment of an eye was present. Furthermore, whole eye segmental imaging was performed and ocular distances were calculated to show the validation of the system for whole eye morphological measurement.

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    12. Evaluation of ultrasound and glucose synergy effect on the optical clearing and light penetration for human colon tissue using SD-OCT

      Evaluation of ultrasound and glucose synergy effect on the optical clearing and light penetration for human colon tissue using SD-OCT

      Topical application optical clearing agents (OCAs) can effectively enhance the tissue optical clearing on the human colon tissue, which has been demonstrated in our previous studies. Nevertheless, the strong light scattering still limits the diffusion rate of OCAs and penetration depth of light into the tissue. In this study, in order to further increase the diffusion of the OCA of glucose into tissue, we employ a method to improve the glucose permeability and light penetration with ultrasound (sonophoretic delivery, SP) and glucose (G) synergy on human normal and cancerous colon tissues in vitro, which was measured and quantified with spectral-domain ...

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    13. Noninvasive Imaging and Measurement of Accommodation Using Dual-Channel SD-OCT

      Noninvasive Imaging and Measurement of Accommodation Using Dual-Channel SD-OCT

      Purpose : To investigate the feasibility and practicality of real-time noninvasive imaging and measurement of ocular accommodation (0–5D with one diopter step) using dual-channel , dual-focus spectral domain optical coherence tomography ( SD-OCT ). Materials and Methods : A custom-built, dual-channel , dual-focus SD-OCT was used to image the anterior segment, including the cornea, iris, and anterior and posterior lens surfaces. Three consecutive measurements were taken in each accommodative session for each subject. Changes in ocular dimensions during accommodation were calculated based on the acquired SD-OCT images . A Friedman test was used to test sensitivity of ocular dimension changes per diopter of accommodation . Results : With ...

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    14. Ex vivo determination of glucose permeability and optical attenuation coefficient in normal and adenomatous human colon tissues using spectral domain optical coherence tomography

      Ex vivo determination of glucose permeability and optical attenuation coefficient in normal and adenomatous human colon tissues using spectral domain optical coherence tomography
      Recent reports have suggested that spectral domain optical coherence tomography (SD-OCT) is a useful tool for quantifying the permeability of hyperosmotic agents in various tissues. We report our preliminary results on quantification of glucose diffusion and assessment of the optical attenuation change due to the diffusion of glucose in normal and adenomatous human colon tissues in vitro by using a SD-OCT and then calculated the permeability coefficients (PC) and optical attenuation coefficients (AC). The PC of a 30% aqueous solution of glucose was 3.37 ± 0.23 × 10 − 6     cm / s in normal tissue and 5.65 ± 0.16 × 10 ...
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    15. Feature Of The Week 3/18/12: Research Results from Shanghai Jiaotong University on Optical Coherence Tomography for Whole Eye Segment Imaging

      Feature Of The Week 3/18/12: Research Results from Shanghai Jiaotong University on Optical Coherence Tomography for Whole Eye Segment Imaging

      Researchers from Shanghai Jiao Tong University, Shanghai Institute of Technology, Peking University, and UCLA recently published a paper on “Optical coherence tomography for whole eye segment imaging". Below is a summary of their work. We proposed a dual focus dual channel spectral domain optical coherence tomography (SD-OCT) for simultaneous imaging of the whole eye segments from cornea to the retina. By using dual channels the system solved the problem of limited imaging depth of SD-OCT. By using dual focus the system solved the problem of simultaneous light focusing on the anterior segment of the eye and the retina. Dual focusing ...

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    16. Optical coherence tomography for whole eye segment imaging

      Optical coherence tomography for whole eye segment imaging

      We proposed a dual focus dual channel spectral domain optical coherence tomography (SD-OCT) for simultaneous imaging of the whole eye segments from cornea to the retina. By using dual channels the system solved the problem of limited imaging depth of SD-OCT. By using dual focus the system solved the problem of simultaneous light focusing on the anterior segment of the eye and the retina. Dual focusing was achieved by adjusting the collimating lenses so the divergence of the two probing beams was tuned to make them focused at different depth in the eye. We further achieved full range complex (FRC ...

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    17. In-vivo full depth of eye imaging spectral domain optical coherence tomography

      In-vivo full depth of eye imaging spectral domain optical coherence tomography

      It is necessary to apply the spectral-domain optical coherence tomography (SD-OCT) to image the whole eye segment for practically iatrical application, but the imaging depth of SD-OCT is limited by the spectral resolution of the spectrometer. By now, no result about this research has been reported. In our study, a new dual channel dual focus OCT system is adopted to image the whole eye segment. The cornea and the crystalline lens are simultaneously imaged by using full range complex spectral-domain OCT in one channel, the retina is detected by the other. The new system was successfully tested in imaging of ...

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    18. Evaluation of spectrometric parameters in spectral-domain optical coherence tomography

      Evaluation of spectrometric parameters in spectral-domain optical coherence tomography

      The parameters of the spectrometer were analyzed in order to optimize the performance of spectral-domain optical coherence tomography (SD-OCT). Because probing depth is proportional to spectral resolution, it can be increased with the choice of a higher resolution spectrometer, which implies greater pixel numbers and lower imaging speed, or by sacrificing part of the spectrum, which compromises the axial resolution and side lobes. With a dynamic range of 8 bits or more, the signal-to-noise ratio remains constant for different noise levels. The results were verified experimentally with in vivo retinal SD-OCT imaging.

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    19. Comparison of different focusing systems for common-path optical coherence tomography with fiber-optic bundle as endoscopic probe

      A fiber-optic bundle–based submillimeter probe for endoscopic common-path optical coherence tomography with focusing system is presented. Three different focusing systems, bulk lenses, a gradient index (GRIN) lens, and a microlens array, are proposed and compared. The simulation results show that all the focusing systems can focus the beam with different degrees of effectiveness. The major differences between the different focusing systems exist in the beam size and the divergence angle between the inner and outer pixels of the fiber bundle. The microlens array shows the smallest change in beam size from the central fiber to the outermost fiber, while ...

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    1-19 of 19
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    1. (18 articles) Qiushi Ren
    2. (13 articles) Shanghai Jiao Tong University
    3. (13 articles) Chuanqing Zhou
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    6. (5 articles) Shuliang Jiao
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    Evaluation of spectrometric parameters in spectral-domain optical coherence tomography In-vivo full depth of eye imaging spectral domain optical coherence tomography Optical coherence tomography for whole eye segment imaging Feature Of The Week 3/18/12: Research Results from Shanghai Jiaotong University on Optical Coherence Tomography for Whole Eye Segment Imaging Ex vivo determination of glucose permeability and optical attenuation coefficient in normal and adenomatous human colon tissues using spectral domain optical coherence tomography Noninvasive Imaging and Measurement of Accommodation Using Dual-Channel SD-OCT Evaluation of ultrasound and glucose synergy effect on the optical clearing and light penetration for human colon tissue using SD-OCT Dual-channel spectral-domain optical-coherence tomography system based on 3 × 3 fiber coupler for extended imaging range Dual band dual focus optical coherence tomography for imaging the whole eye segment Factors Associated with Changes in Retinal Layers Following Acute Optic Neuritis: A Longitudinal Study Using Optical Coherence Tomography Relationship between N95 Amplitude of Pattern Electroretinogram and Optical Coherence Tomography Angiography in Open-Angle Glaucoma Historic Effort to 'End Blindness" Marks a Major Milestone with Leading Scientist Recognized for Pioneering Work at VIP Ceremony Featuring Tribute to Ruth Bader Ginsburg