Dr. Peng Li Profile

Dr. Peng Li

SPIE Involvement:

Conference Program Committee | Author

Area of Expertise:

Biomedical optical imaging , optical coherence tomography angiography , optical coherence tomography

Websites:

Personal Website

Publications (19)

Proceedings Article | 13 March 2024 Presentation

Functional OCT angiography reveals early retinal neurovascular dysfunction in diabetes with capillary resolution

Kaiyuan Liu, Peng Li

Proceedings Volume PC12841, PC1284108 (2024) https://doi.org/10.1117/12.3002483

KEYWORDS: Capillaries, Optical coherence tomography, Angiography, Image resolution, Stereoscopy, Pathophysiology, Neurovascular coupling, Image segmentation

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Proceedings Article | 27 March 2023 Poster

Dynamic inverse SNR-decorrelation OCT angiography with GPU acceleration

Kaiyuan Liu, Tiepei Zhu, Xiaoting Yin, Juan Ye, Peng Li

Proceedings Volume PC12378, PC123780F (2023) https://doi.org/10.1117/12.2648978

KEYWORDS: Angiography, Optical coherence tomography, Hemodynamics, Data processing, Signal to noise ratio, Retina, Data acquisition, 3D acquisition

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Proceedings Article | 2 March 2022 Presentation

Noninvasive OCTA-based blood glucometry

Kaiyuan Liu, Tiepei Zhu, Lin Yao, Ziyi Zhang, Huakun Li, Juan Ye, Peng Li

Proceedings Volume PC11959, PC1195902 (2022) https://doi.org/10.1117/12.2612328

KEYWORDS: Blood, Signal attenuation, Retina, Glucose, Veins, Arteries, Tissues, Tissue optics, Optical coherence tomography, In vivo imaging

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Proceedings Article | 5 March 2021 Presentation

Improvement of decorrelation-based OCT angiography by an adaptive spatial-temporal kernel in monitoring stimulus-evoked hemodynamic responses

Ruixiang Chen, Lin Yao, Kaiyuan Liu, Tongtong Cao, Huakun Li, Peng Li

Proceedings Volume 11641, 116410E (2021) https://doi.org/10.1117/12.2577517

KEYWORDS: Hemodynamics, Optical coherence tomography, Angiography, Numerical simulations, Motion models, Motion analysis, Blood circulation

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SPIE Journal Paper | 31 March 2020 Open Access

INS-fOCT: a label-free, all-optical method for simultaneously manipulating and mapping brain function

Ying Zhang, Lin Yao, Fen Yang, Shanshan Yang, Akshay Edathodathil, Wang Xi, Anna Wang Roe, Peng Li

NPh, Vol. 7, Issue 01, 015014, (March 2020) https://doi.org/10.1117/12.10.1117/1.NPh.7.1.015014

KEYWORDS: Optical coherence tomography, Brain, Scattering, Tissue optics, Brain mapping, Neurophotonics, Light scattering, Optical imaging, Hemodynamics, Tissues

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Proceedings Article | 20 December 2019 Paper

Longitudinal monitoring of blood perfusion and brain tissue damage in photothrombotic ischemic stroke rat model

Shanshan Yang, Kezhou Liu, Guoqing Weng, Zhihua Ding, Peng Li

Proceedings Volume 11209, 112094C (2019) https://doi.org/10.1117/12.2549564

KEYWORDS: Optical coherence tomography, Brain, Light scattering, Scattering, Ischemic stroke

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Proceedings Article | 14 March 2018 Presentation

Hybrid averaging optical coherence tomography angiography and applications in brain (Conference Presentation)

Peng Li, Pei Li, Shanshan Yang, Zhihua Ding

Proceedings Volume 10481, 104810O (2018) https://doi.org/10.1117/12.2289926

KEYWORDS: Optical coherence tomography, Angiography, Image resolution, Tissues, Brain, Medical imaging, Imaging systems, In vivo imaging, Visualization, 3D image processing

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Proceedings Article | 19 April 2017 Presentation

Angular compounded OCTA for flow contrast enhancement (Conference Presentation)

Peng Li, Pei Li, Yuxuan Cheng, Liping Zhou, Zhihua Ding

Proceedings Volume 10053, 1005314 (2017) https://doi.org/10.1117/12.2254751

KEYWORDS: Lithium, Optical coherence tomography, Angiography, Modulation, Tissue optics, Blood circulation, Biological research, Light scattering, Fourier transforms, In vivo imaging

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SPIE Journal Paper | 24 August 2016 Open Access

Angular compounding by full-channel B-scan modulation encoding for optical coherence tomography speckle reduction

Pei Li, Liping Zhou, Yang Ni, Zhihua Ding, Peng Li

JBO, Vol. 21, Issue 08, 086014, (August 2016) https://doi.org/10.1117/12.10.1117/1.JBO.21.8.086014

KEYWORDS: Speckle, Modulation, Optical coherence tomography, Computer programming, Laser beam diagnostics, Mirrors, Fourier transforms, Lithium, In vivo imaging, Gaussian filters

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We describe an angular compounding method by full-channel B-scan modulation encoding for speckle reduction in optical coherence tomography. The complex-valued spectral interferogram (SI) is reconstructed by removing one of the conjugate terms in the depth space. Fourier transform of the complex SI along the lateral direction enables a full-channel (with both negative and positive Fourier space) for B-scan modulation in the spatial frequency (ν) domain. A full-size probe beam, determined by the scanning mirror size, is centered on the mirror pivot, which allows the negative and positive half-channels working in parallel. Compared with the existing method, where only a half-channel (negative or positive) works alone, the proposed full-channel method offers more than twice the performance in speckle reduction. The feasibility of the proposed full-space approach is validated through both the phantom and in vivo human thumbnail experiments.

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SPIE Journal Paper | 7 March 2016

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

Li Guo, Rui Shi, Chao Zhang, Dan Zhu, Zhihua Ding, Peng Li

JBO, Vol. 21, Issue 08, 081202, (March 2016) https://doi.org/10.1117/12.10.1117/1.JBO.21.8.081202

KEYWORDS: Optical coherence tomography, Skin, Blood circulation, Signal attenuation, Optical clearing, Angiography, Optical properties, Scattering, Tissue optics, Tissues

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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%) and refractive-index mismatching (more than ∼25.3%) in the superficial (epidermal, dermal, and hypodermal) layers. A high correlation (up to ∼90%) between the relative changes in refractive-index mismatching and Angio-OCT signal strength is measured. The optical clearing rate is ∼5.83×10−5 cm/s. In addition, Angio-OCT demonstrates enhanced performance in imaging cutaneous hemodynamics with satisfactory spatiotemporal resolution and contrast when combined with TOC, which exhibits a powerful practical application in studying microcirculation.

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SPIE Journal Paper | 2 November 2015

Statistical analysis of motion contrast in optical coherence tomography angiography

Yuxuan Cheng, Li Guo, Cong Pan, Tongtong Lu, Tianyu Hong, Zhihua Ding, Peng Li

JBO, Vol. 20, Issue 11, 116004, (November 2015) https://doi.org/10.1117/12.10.1117/1.JBO.20.11.116004

KEYWORDS: Optical coherence tomography, Angiography, Statistical analysis, Scattering, Advanced distributed simulations, Mathematical modeling, Motion models, Blood circulation, Tissues, Cadmium

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Optical coherence tomography angiography (Angio-OCT), mainly based on the temporal dynamics of OCT scattering signals, has found a range of potential applications in clinical and scientific research. Based on the model of random phasor sums, temporal statistics of the complex-valued OCT signals are mathematically described. Statistical distributions of the amplitude differential and complex differential Angio-OCT signals are derived. The theories are validated through the flow phantom and live animal experiments. Using the model developed, the origin of the motion contrast in Angio-OCT is mathematically explained, and the implications in the improvement of motion contrast are further discussed, including threshold determination and its residual classification error, averaging method, and scanning protocol. The proposed mathematical model of Angio-OCT signals can aid in the optimal design of the system and associated algorithms.

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SPIE Journal Paper | 9 September 2014

Visualization of the ocular pulse in the anterior chamber of the mouse eye in vivo using phase-sensitive optical coherence tomography

Peng Li, Zhihua Ding, Yang Ni, Baishen Xu, Chen Zhao, Yi Shen, Chixin Du, Bo Jiang

JBO, Vol. 19, Issue 09, 090502, (September 2014) https://doi.org/10.1117/12.10.1117/1.JBO.19.9.090502

KEYWORDS: Optical coherence tomography, Cornea, Visualization, Eye, In vivo imaging, Tissues, Image segmentation, Lithium, Crystals, Signal to noise ratio

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We report on a phase-based method for accurately measuring the ocular pulse in the anterior chamber in vivo. Using phase-sensitive optical coherence tomography with optimized scanning protocols and equations for compensating bulk motion and environmental vibrations, a high sensitivity of 0.9 μm/s minimal velocity is demonstrated at a wide detection band of 0 to 380 Hz. The pulsatile relative motion between cornea and crystalline lens in rodents is visualized and quantified. The relative motion is most likely caused by respiration (1.6 Hz) and heartbeat (6.6 Hz). The velocity amplitude of the relative motion is 10.3±2.4 μm/s. The displacement amplitudes at the respiratory and cardiac frequencies are 202.5±64.9 and 179.9±49.4 nm, respectively. The potential applications of the measurement technique can be found in the evaluation of intraocular pressure and the measurement of biomechanical properties of the ocular tissue, which are important in several ocular diseases.

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Proceedings Article | 26 March 2013

In vivo functional imaging of embryonic chick heart using ultrafast 1310nm-band spectral domain optical coherence tomography

Peng Li, Xin Yin, Ruikang Wang

Proceedings Volume 8593, 859304 (2013) https://doi.org/10.1117/12.2004773

KEYWORDS: Heart, Blood circulation, Optical coherence tomography, Doppler effect, Phase shifts, Ultrafast imaging, Tissues, Functional imaging, Signal to noise ratio, In vivo imaging

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During the cardiac development, the cardiac wall and the blood flow actively interact with each other, and determine the biomechanical environment to which the embryonic heart exposes. Employing an ultrafast 1310nm-band dual-camera spectral domain optical coherence tomography (SDOCT), the radial strain rate of the myocardial wall can be extracted with high signal-to-noise ratio, at the same time the Doppler velocity of the blood flow can also be displayed. The ability to simultaneously characterize these two cardiac tissues provides a powerful approach to better understand the interaction between the cardiac wall and the blood flow, which is important to the investigation of cardiac development.

Proceedings Article | 20 March 2013

Phase-sensitive optical coherence tomography characterization of pulse-induced trabecular meshwork displacement in ex vivo non-human primate eyes

Peng Li, Roberto Reif, Zhongwei Zhi, Lin An, Elizabeth Martin, Tueng Shen, Murray Johnstone, Ruikang Wang

Proceedings Volume 8571, 85711S (2013) https://doi.org/10.1117/12.2006992

KEYWORDS: Optical coherence tomography, Tissues, Mercury, Eye, Tissue optics, Imaging systems, Veins, Resistance, Image segmentation, Visualization

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Purpose. It is suspected that the abnormalities of aqueous outflow pump composed of trabecular meshwork (TM) and Schlemm’s canal (SC) results in the increased outflow resistance and then elevated intraocular pressure (IOP) in initial glaucoma. In order to explore the casual mechanism and the early diagnosis of glaucoma, the dynamic characterizations of aqueous outflow pump were explored.
Methods. As a functional extension of optical coherence tomography (OCT), tissue Doppler OCT (tissue-DOCT) method capable of measuring the slow tissue movement was developed. The tissue-DOCT imaging was conducted on the corneo-scleral limbus of 4 monkey eyes. The eye was mounted in an anterior segment holder, together with a perfusion system to control the mean IOP and to induce the cyclic IOP transients with amplitude 3 mm Hg at frequency 1 pulse/second. IOP was monitored on-line by a pressure transducer. Tissue-DOCT data and pressure data were recorded simultaneously. The IOP-transient induced Doppler velocity, displacement and strain rate of TM and the normalized area of SC were quantified at 7 different mean IOPs (5, 8, 10, 20, 30, 40, 50 mm Hg).
Results. The outflow system, including TM, SC and CCs, was visualized in the micro-structural imaging. The IOP-transient induced pulsatile TM movement and SC deformation were detected and quantified by tissue-DOCT. The TM movement was depth-dependent and the largest movement was located in the area closest to SC endothelium (SCE). Both the pulsations of TM and SC were found to be synchronous with the IOP pulse wave. At 8 mm Hg IOP, the global TM movement was around 0.65μm during one IOP transient. As IOP elevated, a gradual attenuation of TM movement and SC deformation was observed.
Conclusions. The observed pulsation of TM and SC induced by the pulsatile IOP transients was in good agreement with the predicated role of TM and SC acting as a biomechanical pump (pumping aqueous from anterior chamber into SC and from SC into CCs) in the aqueous outflow system. As the IOP elevated, the attenuated pulsation amplitude of the aqueous outflow pump indicated the failure of the mechanical pump and the increase of aqueous outflow resistance. The promising results revealed the potential of using the proposed tissue-DOCT for diagnosis and associated therapeutic guidance of the initial and progressive glaucoma process by monitoring the pulsation of the outflow pump.

SPIE Journal Paper | 18 January 2013

Extended imaging depth to 12 mm for 1050-nm spectral domain optical coherence tomography for imaging the whole anterior segment of the human eye at 120-kHz A-scan rate

Peng Li, Lin An, Gongpu Lan, Murray Johnstone, Douglas Malchow, Ruikang Wang

JBO, Vol. 18, Issue 01, 016012, (January 2013) https://doi.org/10.1117/12.10.1117/1.JBO.18.1.016012

KEYWORDS: Imaging systems, Optical coherence tomography, Image segmentation, Cameras, Eye, Image resolution, Line scan image sensors, Coherence imaging, Spectral resolution, Indium gallium arsenide

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We demonstrate a 1050-nm spectral domain optical coherence tomography (OCT) system with a 12 mm imaging depth in air, a 120 kHz A-scan rate and a 10 μm axial resolution for anterior-segment imaging of human eye, in which a new prototype InGaAs linescan camera with 2048 active-pixel photodiodes is employed to record OCT spectral interferograms in parallel. Combined with the full-range complex technique, we show that the system delivers comparable imaging performance to that of a swept-source OCT with similar system specifications.

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SPIE Journal Paper | 3 December 2012

Optical coherence tomography provides an ability to assess mechanical property of cardiac wall of developing outflow tract in embryonic heart in vivo

Peng Li, Ruikang Wang

JBO, Vol. 17, Issue 12, 120502, (December 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.12.120502

KEYWORDS: Optical coherence tomography, Heart, In vivo imaging, Wave propagation, Blood, Tissues, Protactinium, Image segmentation, Imaging systems, Hemodynamics

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Knowledge of the biomechanical/elastic property of the cardiac wall is of fundamental importance in improving our understanding of cardiac development, particularly the interaction between the wall dynamics and hemodynamics in the developing outflow tract (OFT). We describe a method that employs optical coherence tomography (OCT) as a means to noninvasively measure the local elastic property of the cardiac wall in vivo. The method uses a time-lapse sequence of OCT images that represent the dynamic behavior of the OFT longitudinal section to calculate the regional wall pulse wave velocity (PWV), upon which the Young's modulus of the cardiac wall is deduced by the use of the Moens-Korteweg equation. The experimental results show that the foot-to-foot PWV ranges from 3.2 to 6.6 mm/s with a mean of 4.7 mm/s, and the averaged Young's modulus is 0.36 Pa, both of which are comparable to the documented values of stage HH17 atrioventricular canal tissue. The proposed method that provides the quantitative mechanical assessment may play a significant role in the understanding of the cardiac development.

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SPIE Journal Paper | 6 September 2012

In vivo functional imaging of blood flow and wall strain rate in outflow tract of embryonic chick heart using ultrafast spectral domain optical coherence tomography

Peng Li, Ruikang Wang, Xin Yin, Liang Shi, Sandra Rugonyi

JBO, Vol. 17, Issue 9, 096006, (September 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.9.096006

KEYWORDS: Optical coherence tomography, Blood circulation, Heart, Doppler effect, Blood, Tissues, Imaging systems, In vivo imaging, Functional imaging, Ultrafast imaging

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During cardiac development, the cardiac wall and flowing blood are two important cardiac tissues that constantly interact with each other. This dynamic interaction defines appropriate biomechanical environment to which the embryonic heart is exposed. Quantitative assessment of the dynamic parameters of wall tissues and blood flow is required to further our understanding of cardiac development. We report the use of an ultrafast 1310-nm dual-camera spectral domain optical coherence tomography (SDOCT) system to characterize/image, in parallel, the dynamic radial strain rate of the myocardial wall and the Doppler velocity of the underlying flowing blood within an in vivo beating chick embryo. The OCT system operates at 184-kHz line scan rate, providing the flexibility of imaging the fast blood flow and the slow tissue deformation within one scan. The ability to simultaneously characterize tissue motion and blood flow provides a useful approach to better understand cardiac dynamics during early developmental stages.

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SPIE Journal Paper | 24 July 2012

Phase-sensitive optical coherence tomography characterization of pulse-induced trabecular meshwork displacement in ex vivo nonhuman primate eyes

Peng Li, Roberto Reif, Zhongwei Zhi, Tueng Shen, Ruikang Wang, Elizabeth Martin, Murray Johnstone

JBO, Vol. 17, Issue 7, 076026, (July 2012) https://doi.org/10.1117/12.10.1117/1.JBO.17.7.076026

KEYWORDS: Optical coherence tomography, Tissues, Eye, In vivo imaging, Imaging systems, Adaptive optics, Image segmentation, Visualization, Eye models, Visual system

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Glaucoma is a blinding disease for which intraocular pressure (IOP) is the only treatable risk factor. The mean IOP is regulated through the aqueous outflow system, which contains the trabecular meshwork (TM). Considerable evidence indicates that trabecular tissue movement regulates the aqueous outflow and becomes abnormal during glaucoma; however, such motion has thus far escaped detection. The purpose of this study is to describe anovel use of a phase-sensitive optical coherence tomography (PhS-OCT) method to assess pulse-dependent TM movement. For this study, we used enucleated monkey eyes, each mounted in an anterior segment holder. A perfusion system was used to control the mean IOP as well as to provide IOP sinusoidal transients (amplitude 3 mmHg, frequency 1 pulse/second) in all experiments. Measurements were carried out at seven graded mean IOPs (5, 8, 10, 20, 30, 40, and 50 mm Hg). We demonstrate that PhS-OCT is sensitive enough to image/visualize TM movement synchronous with the pulse-induced IOP transients, providing quantitative measurements of dynamic parameters such as velocity, displacement, and strain rate that are important for assessing the biomechanical compliance of the TM. We find that the largest TM displacement is in the area closest to Schlemm's canal (SC) endothelium. While maintaining constant ocular pulse amplitude, an increase of mean IOP results in a decrease of TM displacement and mean size of the SC. These results demonstrate that the PhS-OCT is a useful imaging technique capable of assessing functional properties necessary to maintain IOP in a healthy range, offering a new diagnostic alternative for glaucoma.

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SPIE Journal Paper | 1 September 2011

Optical microangiography provides an ability to monitor responses of cerebral microcirculation to hypoxia and hyperoxia in mice

Yali Jia, Peng Li, Ruikang Wang

JBO, Vol. 16, Issue 09, 096019, (September 2011) https://doi.org/10.1117/12.10.1117/1.3625238

KEYWORDS: Hypoxia, Hyperoxia, Capillaries, Blood circulation, Brain, Oxygen, Doppler tomography, Biomedical optics, In vivo imaging, Tissues

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In vivo imaging of microcirculation can improve our fundamental understanding of cerebral microhemodynamics under various physiological challenges, such as hypoxia and hyperoxia. However, existing techniques often involve the use of invasive procedures or exogenous contrast agents, which would inevitably perturb the intrinsic physiologic responses of microcirculation being investigated. We report ultrahigh sensitive optical microangiography (OMAG) for label-free monitoring of microcirculation responses challenged by oxygen inhalation. For the first time, we demonstrate that OMAG is capable of showing the impact of acute hypoxia and hyperoxia on microhemodynamic activities, including the passive and active modulation of microvascular density and flux regulation, within capillary and noncapillary vessels in rodents in vivo. The ability of OMAG to functionally image the intact microcirculation promises future applications for studying cerebral diseases.

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Conference Committee Involvement (5)

Dynamics and Fluctuations in Biomedical Photonics XXII

25 January 2025 | San Francisco, California, United States

Dynamics and Fluctuations in Biomedical Photonics XXI

28 January 2024 | San Francisco, California, United States

Dynamics and Fluctuations in Biomedical Photonics XX

29 January 2023 | San Francisco, California, United States

Dynamics and Fluctuations in Biomedical Photonics XIX

22 January 2022 | San Francisco, California, United States

Dynamics and Fluctuations in Biomedical Photonics XVIII

6 March 2021 | Online Only, California, United States

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