All Articles from Yan Li -Optical Coherence Tomography News

Articles from Yan Li

1-24 of 51 1 2 3 »
1. Cerebral edema detection in vivo after middle cerebral artery occlusion using swept-source optical coherence tomography
  
  Explore SPIE Digital Library Nov 12 2019 Neurology
  
  Cerebral edema is a severe complication of ischemic cerebrovascular disease, which can lead to microcirculation compression resulting in additional ischemic damage. Real-time and continuous in vivo imaging techniques for edema detection are of great significance to basic research on cerebral edema. We attempted to monitor the cerebral edema status in rats with middle cerebral artery occlusion (MCAO) over time, using a wide field-of-view swept-source optical coherence tomography (SS-OCT) system. Optical attenuation coefficients (OACs) were calculated by an optimized depth-resolved estimation method, and en face OAC maps covering the whole cortex were obtained. Then, the tissue affected by edema was segmented ...
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  Mentions: University of Michigan Yan Li
2. Simultaneous detection of cerebral blood perfusion and cerebral edema using swept‐source optical coherence tomography
  
  Explore Wiley Online Library Nov 12 2019 Neurology
  
  The progression of ischemic cerebral edema (CE) is closely related to the level of cerebral blood perfusion (CBP) and affects each other. Simultaneous detection of CBP and CE is helpful in understanding the mechanisms of ischemic cerebral edema development. In this article, a wide field of view (FOV) SS‐OCT system was used to detect CE status and CBP levels simultaneously in middle cerebral artery occlusion (MCAO) rats. Images reflecting these two physiological states can be reconstructed with only one C‐scan. We quantify these two physiological states into 4 parameters, which contain two vascular parameters (vascular displacement distance and ...
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3. Multimodal endoscopy for colorectal cancer detection by optical coherence tomography and near-infrared fluorescence imaging
  
  Explore OSA | OSA Publishing Apr 20 2019 Gastroenterology
  
  While colonoscopy is the gold standard for diagnosis and classification of colorectal cancer (CRC), its sensitivity and specificity are operator-dependent and are especially poor for small and flat lesions. Contemporary imaging modalities, such as optical coherence tomography (OCT) and near-infrared (NIR) fluorescence, have been investigated to visualize microvasculature and morphological changes for detecting early stage CRC in the gastrointestinal (GI) tract. In our study, we developed a multimodal endoscopic system with simultaneous co-registered OCT and NIR fluorescence imaging. By introducing a contrast agent into the vascular network, NIR fluorescence is able to highlight the cancer-suspected area based on significant change ...
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  Mentions: Zhongping Chen UC Irvine Yan Li
4. 1.7 micron optical coherence tomography for vaginal tissue characterization in vivo
  
  Explore Wiley Online Library Jul 30 2018 Gynecology
  
  Objectives Optical coherence tomography (OCT) can noninvasively visualize in vivo tissue microstructure with high spatial resolution that approaches the histologic level. Currently, OCT studies in gynecology are few and limited to a conventional 1.3 μm center wavelength swept light source which provides high spatial resolution but limited penetration depth. Here, we present a novel endoscopic OCT system with improved penetration depth and high resolution. Methods A novel endoscopic OCT system was developed based on a 1.7 µm swept source laser, which is capable of deeper tissue penetration due to its longer wavelength. To evaluate the performance of system ...
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  Mentions: Zhongping Chen UC Irvine Yan Li
5. Deep imaging in highly scattering media by combining reflection matrix measurement with Bessel-like beam based optical coherence tomography
  
  Explore aip.scitation.org Jul 7 2018
  
  Multiple scattering in biomedical tissue limits the imaging depth within a range of 1–2 mm for conventional optical imaging techniques. To extend the imaging depth into the scattering medium, a computational method based on the reflection matrix measurement has been developed to retrieve the singly back-scattered signal light from the dominant detrimental multiple-scattered background. After applying singular value decomposition on the measured matrix in the post-process, the target image underneath the turbid media is clearly recovered. To increase the depth of focus of the incident light by elongating the focal spot along the optical axis, a digital grating pattern ...
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  Mentions: Zhongping Chen UC Irvine Yan Li
6. Multimodality endoscopic optical coherence tomography and fluorescence imaging technology for visualization of layered architecture and subsurface microvasculature
  
  Explore OSA | OSA Publishing May 2 2018 Gastroenterology , Probes
  
  Endoscopic imaging technologies, such as endoscopic optical coherence tomography (OCT) and near-infrared fluorescence, have been used to investigate vascular and morphological changes as hallmarks of early cancer in the gastrointestinal tract. Here we developed a high-speed multimodality endoscopic OCT and fluorescence imaging system. Using this system, the architectural morphology and vasculature of the rectum wall were obtained simultaneously from a Sprague Dawley rat in vivo . This multimodality imaging strategy in a single imaging system permits the use of a single imaging probe, thereby improving prognosis by early detection and reducing costs.
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  Mentions: Zhongping Chen UC Irvine Yan Li
7. Optical coherence tomography angiography of a pigmented Fuchs' adenoma (age-related hyperplasia of the nonpigmented ciliary body epithelium) masquerading as a ciliary body melanoma
  
  Explore ScienceDirect Jan 13 2018 Ophthalmology
  
  Purpose To report a case of age-related hypertrophy of the nonpigmented ciliary epithelium (ARH-NPCE) clinically resembling a ciliary body melanoma and report the optical coherence tomography angiography (OCTA) findings associated with this lesion. Observations A 51-year-old male was referred for evaluation of a deeply pigmented ciliary body mass with extension through the iris root. Iridocyclectomy was performed due to concern for ciliary body melanoma. Histopathologic analysis was instead consistent with ARH-NPCE, also known as Fuchs' adenoma. Prior to surgery, OCTA images revealed abnormal vasculature in the area of the lesion. Vessels in the peripheral iris approaching the lesion appeared more ...
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  Mentions: David Huang Oregon Health & Science University Center for Ophthalmic Optics and Lasers
8. Imaging of Iris Lesions With High-Speed Optical Coherence Tomography
  
  Explore m4.healio.com Dec 3 2017 Ophthalmology
  
  n BACKGROUND AND OBJECTIVES:To image and measure iris tumors with optical coherence tomography (OCT). n PATIENTS AND METHODS:High-speed(2,000– 4,000 axial-scan/sec and 4–16 frames/sec) 1.3-micron wavelength anterior segment OCT prototypes were used to image 6 eyes of 6 patients with a variety of iris lesions, including focal iris nevus, diffuse iris nevus, amelanotic iris nevus, iris melanocytosis, and iris melanoma. OCT images were compared with slit-lamp photography and ultrasound biomicroscopy. n RESULTS: OCT at 1.3-micron wavelength could penetrate the full thickness of the iris lesions and allow three-dimensional measurement of lesion ...
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  Mentions: Joseph A. Izatt Andrew M. Rollins David Huang
9. Intravascular Optical Coherence Tomography for Characterization of Atherosclerosis with a 1.7 Micron Swept-Source Laser
  
  Explore Nature Publishing Group Nov 15 2017 Cardiology
  
  The main cause of acute coronary events, such as thrombosis, is the rupture of atherosclerotic plaques. Typical intravascular optical coherence tomography (IVOCT) imaging systems that utilize a 1.3 μm swept source laser are often used for identifying fibrous cap thickness of plaques, yet cannot provide adequate depth penetration to resolve the size of the lipid pool. Here, we present a novel IVOCT system with a 1.7 μm center wavelength swept light source that can readily penetrate deeper into the tissue because of the longer wavelength and allows for better identification of plaques due to the lipid absorption spectrum ...
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  Mentions: Zhongping Chen UC Irvine Yan Li
10. Methods and systems to measure corneal epithelial thickness and power, stromal thickness, subepithelial corneal power and topography for disease diagnosis
  
  Explore uspto.gov May 23 2017 Ophthalmology , Patents
  
  This invention discloses methods and systems for measuring corneal epithelial thickness and power, stromal thickness, subepitheila corneal power and topography. The systems and methods disclosed herein are non-invasive, non-contact and automated imaging methods which preferably makes use of Fourier-domain optical tomography. Also disclosed herein are scanning patterns and image analysis methods for utilizing and analyzing Fourier-domain optical coherence tomography images to obtain information about conical epithelial and stromal properties as well as parameters useful for evaluating the properties. The methods and systems described herein are useful as eye disease diagnostic tools and eye surgery planning tools.
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  Mentions: David Huang University of Southern California Ou Tan
11. Extended axial imaging range, widefield swept source optical coherence tomography angiography
  
  Explore Wiley Online Library May 11 2017
  
  We developed a high-speed, swept source OCT system for widefield OCT angiography (OCTA) imaging. The system has an extended axial imaging range of 6.6 mm. An electrical lens is used for fast, automatic focusing. The recently developed split-spectrum amplitude and phase-gradient angiography allow high-resolution OCTA imaging with only two B-scan repetitions. An improved post-processing algorithm effectively removed trigger jitter artifacts and reduced noise in the flow signal. We demonstrated high contrast 3 mm×3 mm OCTA image with 400×400 pixels acquired in 3 seconds and high-definition 8 mm×6 mm and 12 mm×6 mm OCTA images with ...
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  Mentions: David Huang Oregon Health & Science University UC Irvine
12. Distinguishing between contact lens warpage and ectasia: Usefulness of optical coherence tomography epithelial thickness mapping
  
  Explore Journal of Cataract & Refractive Surgery Mar 24 2017 Ophthalmology
  
  Purpose To distinguish between corneal ectasia and contact lens–related warpage by characteristic patterns on corneal topography and optical coherence tomography (OCT) epithelial thickness maps. Setting Casey Eye Institute, Portland, Oregon, USA. Design Prospective and retrospective case series. Methods Axial and mean power maps were obtained on corneal topography systems. Epithelial thickness maps were generated using RTVue OCT. A sector divider was applied to all maps. The locations of the minimum epithelial thickness, maximum epithelial thickness, maximum axial power, and maximum mean power were determined based on sector averages. Agreement was defined as the extremums occurring in the same or ...
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  Mentions: David Huang Oregon Health & Science University Optovue RTVue-100
13. Fully integrated optical coherence tomography, ultrasound, and indocyanine green-based fluorescence tri-modality system for intravascular imaging
  
  Explore OSA | OSA Publishing Jan 28 2017 Cardiology
  
  We present a tri-modality imaging system and fully integrated tri-modality probe for intravascular imaging. The tri-modality imaging system is able to simultaneously acquire optical coherence tomography (OCT), ultrasound (US), and fluorescence imaging. Moreover, for fluorescence imaging, we used the FDA-approved indocyanine green (ICG) dye as the contrast agent to target lipid-loaded macrophages. We conducted imaging from a male New Zealand white rabbit to evaluate the performance of the tri-modality system. In addition, tri-modality images of rabbit aortas were correlated with hematoxylin and eosin (H&E) histology to check the measurement accuracy. The fully integrated miniature tri-modality probe, together with the ...
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  Mentions: Zhongping Chen UC Irvine Yan Li
14. Optical Coherence Tomography Angiography Characteristics of Iris Melanocytic Tumors
  
  Explore Elsevier Health Nov 14 2016 Oncology , Ophthalmology
  
  Purpose To evaluate tumor vasculature with optical coherence tomography angiography (OCTA) in malignant iris melanomas and benign iris lesions. Design Cross-sectional observational clinical study. Participants Patients with iris lesions and healthy volunteers. Methods Eyes were imaged using OCTA systems operating at 1050- and 840-nm wavelengths. Three-dimensional OCTA scans were acquired. Iris melanoma patients treated with radiation therapy were imaged again after I-125 plaque brachytherapy at 6 and 18 months. Main Outcome Measures OCT and OCTA images, qualitative evaluation of iris and tumor vasculature, and quantitative vessel density. Results One eye each of 8 normal volunteers and 9 patients with iris ...
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  Mentions: Massachusetts Institute of Technology James G. Fujimoto David Huang
15. Subclinical keratoconus detection by pattern analysis of corneal and epithelial thickness maps with optical coherence tomography
  
  Explore ScienceDirect Mar 26 2016 Ophthalmology
  
  Purpose To screen for subclinical keratoconus by analyzing corneal, epithelial, and stromal thickness map patterns with Fourier-domain optical coherence tomography (OCT). Setting Four centers in the United States. Design Cross-sectional observational study. Methods Eyes of normal subjects, subclinical keratoconus eyes, and the topographically normal eye of a unilateral keratoconus patient were studied. Corneas were scanned using a 26 000 Hz Fourier-domain OCT system (RTVue). Normal subjects were divided into training and evaluation groups. Corneal, epithelial, and stromal thickness maps and derived diagnostic indices, including pattern standard deviation (PSD) variables and pachymetric map–based keratoconus risk scores, were calculated from the ...
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  Mentions: David Huang Oregon Health & Science University Ou Tan
16. Imaging the anterior eye with dynamic-focus swept-source optical coherence tomography.
  
  Explore SPIE | Journal Dec 15 2015 Ophthalmology
  
  A custom-built dynamic-focus swept-source optical coherence tomography (SS-OCT) system with a central wavelength of 1310 nm was used to image the anterior eye from the cornea to the lens. An electrically tunable lens was utilized to dynamically control the positions of focusing planes over the imaging range of 10 mm. The B-scan images were acquired consecutively at the same position but with different focus settings. The B-scan images were then registered and averaged after filtering the out-of-focus regions using a Gaussian window. By fusing images obtained at different depth focus locations, high-resolution and high signal-strength images were obtained over the ...
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  Mentions: David Huang Oregon Health & Science University Center for Ophthalmic Optics and Lasers
17. Change of Retinal Nerve Layer Thickness in Non-Arteritic Anterior Ischemic Optic Neuropathy Revealed by Fourier Domain Optical Coherence Tomography
  
  Explore Taylor & Francis Online Nov 19 2015 Ophthalmology
  
  Purpose : To examine the changes of non-arteritic anterior ischemic optic neuropathy (NAION) by serial morphometry using Fourier domain optical coherence tomography (FD-OCT). Materials and methods : Retrospective study in patients with newly diagnosed NAION ( n =33, all unilateral) and controls ( n =75 unilateral NAION patients with full contralateral eye vision) who underwent FD-OCT of the optic disk, optic nerve head (ONH), and macula within 1 week of onset and again 1, 3, 6, and 12 months later. The patients showed no improvement in vision during follow-up. Results : Within 1 week of onset, all NAION eyes exhibited severe ONH fiber crowding and ...
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  Mentions: Yan Li
18. Corneal Epithelial Remodeling after LASIK Measured by Fourier-Domain Optical Coherence Tomography
  
  Explore Hindawi Publishing Corporation Jun 14 2015 Ophthalmology
  
  Purpose . To quantify corneal epithelial thickness changes after myopic LASIK by OCT. Methods. Epithelial thickness before and after myopic LASIK were measured by a Fourier-domain OCT system. Average central (within 1 mm diameter) and paracentral epithelial thickness (5~6 mm diameter) before and after LASIK were compared. Correlation between central epithelial thickness change and laser spherical equivalent setting was evaluated. An epithelial smoothing constant was estimated based on a mathematical model published previously. Results. Nineteen eyes from 11 subjects were included in the study. Eyes had myopic LASIK ranging from −1.69 D to −6.75 D spherical equivalent. The ...
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  Mentions: David Huang Oregon Health & Science University Center for Ophthalmic Optics and Lasers
19. Aqueous Cell Differentiation in Anterior Uveitis Using Fourier-domain Optical Coherence Tomography
  
  Explore iovs.org Feb 5 2015 Ophthalmology
  
  Purpose: The differential diagnosis of a patient presenting with anterior uveitis is broad and can present a diagnostic challenge. In this study, we evaluate the characteristic findings of inflammatory cells on optical coherence tomography (OCT) both in vitro and in vivo. Methods: Blood from two healthy volunteers was prepared using standardized methods for cell sorting with a flow cytometer (FASCAria; BD Biosciences). Neutrophils, lymphocytes, monocytes, and red blood cells were placed in suspension and scanned with a 26 kHz Fourier-domain OCT system (RTVue; Optovue, Inc.) with 5 µm axial resolution. Custom software algorithms were used to identify cells based on ...
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  Mentions: Optovue David Huang Oregon Health & Science University
20. Dual-channel spectral-domain optical-coherence tomography system based on 3 × 3 fiber coupler for extended imaging range
  
  Explore opticsinfobase.org Aug 13 2014
  
  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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  Mentions: Yan Li Peking University Chuanqing Zhou
21. Predicting Transepithelial Phototherapeutic Keratectomy Outcomes Using Fourier Domain Optical Coherence Tomography
  
  Explore LWW Online Jan 24 2014 Ophthalmology
  
  PURPOSE:: The aim of this study was to use Fourier domain optical coherence tomography to predict transepithelial phototherapeutic keratectomy outcomes. METHODS:: This is a prospective case series. Subjects with anterior stromal corneal opacities underwent an excimer laser phototherapeutic keratectomy (PTK) combined with a photorefractive keratectomy using the VISX S4 excimer laser (AMO, Inc, Santa Ana, CA). Preoperative and postoperative Fourier domain optical coherence tomography images were used to develop a simulation algorithm to predict treatment outcomes. Main outcome measures included preoperative and postoperative uncorrected distance visual acuities and corrected distance visual acuity. RESULTS:: Nine eyes of 8 patients were treated ...
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  Mentions: David Huang Oregon Health & Science University Center for Ophthalmic Optics and Lasers
22. NON-INVASIVE 3D Imaging And Measuring Of Anterior Chamber Angle Of The Eye
  
  Explore patentscope.wipo.int Dec 1 2013 Ophthalmology , Patents
  
  Embodiments of OCT measurement and analysis techniques described herein enable precise 3D anterior chamber angle measurement from major, pertinent landmarks in the eye. Such techniques result in a more reliable, quantifiable angle measurement technique that is both non-invasive and non- contact in nature, thereby improving clinical practicality, while improving patient comfort and care.
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  Mentions: David Huang Oregon Health & Science University Center for Ophthalmic Optics and Lasers
23. Keratoconus diagnosis with optical coherence tomography–based pachymetric scoring system
  
  Explore ScienceDirect Oct 29 2013 Ophthalmology
  
  Purpose To develop an optical coherence tomography (OCT) pachymetry map–based keratoconus risk scoring system. Settings Doheny Eye Institute, University of Southern California, Los Angeles, California, and Brass Eye Center, New York, New York, USA; Department of Ophthalmology, Affiliated Eye Hospital of Wenzhou Medical College, Wenzhou, China. Design Cross-sectional study. Methods Fourier-domain OCT was used to acquire corneal pachymetry maps in normal and keratoconus subjects. Pachymetric variables were minimum, minimum−median, superior–inferior (S–I), superonasal–inferotemporal (SN–IT), and the vertical location of the thinnest cornea (Ymin). A logistic regression formula and a scoring system were developed based on ...
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  Mentions: Fudan University David Huang Oregon Health & Science University
24. Anterior Chamber Cell Grading by Optical Coherence Tomography
  
  Explore iovs.org Dec 18 2012 Ophthalmology
  
  Purpose: To quantify cells in the ocular anterior chamber by optical coherence tomography (OCT). Methods: A time-domain anterior segment OCT system was used to image latex microsphere suspensions in vitro and the anterior chamber of uveitis and normal subjects in vivo. The OCT scan pattern, consisting of 2- and 4-mm diameter concentric circular scans, was divided into central, superior, and inferior regions. A computer algorithm was developed to automatically identify particles in OCT images. A uveitis specialist used slit-lamp biomicroscopy to grade the anterior chamber cells on a scale of 0 to 4+. Results: Latex microspheres and anterior chamber cells ...
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  Mentions: David Huang Cleveland Clinic Oregon Health & Science University
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