The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Ruikang K. Wang - One of the best experts on this subject based on the ideXlab platform.
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visualization of oct signal pulsatility at variable tissue depth with optical Microangiography
Dynamics and Fluctuations in Biomedical Photonics XVII, 2020Co-Authors: Zhiying Xie, Qinqin Zhang, Yuxuan Cheng, Geng Wang, Ruikang K. WangAbstract:Pulsatile signals from the cutaneous blood flow could be informative for evaluating the health condition of an individual. One of the popular optical measuring devices, photoplethysmogram (PPG) is often used to detect the pulse signal from skin. However, the origin of the PPG signal still remains controversial. Benefiting from the non-invasive, label-free, 3D imaging tool, optical coherence tomography (OCT) is able to capture the intrinsic tissue signals at different penetration depth in high spatial and temporal resolution. Periodic pulse signal was observed by taking advantage of the optical Microangiography (OMAG) algorithm which is sensitive to the motion of blood flow. The pulsatile pattern from the capillary and arteriole was successfully differentiated and their morphology showed distinct property at different local blood pressure. The pulse signal from the arteriole is more consistent and has similar waveform as the PPG signals. The result indicated that the PPG signal could be deceive by the mixing signal from the capillary bed and arterioles since it measures the total blood volume change in the plexuses. This study may shed some new light on understanding the mechanical property of how blood travel through different types of vasculature networks and elucidate its potential application in disease assessments.
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patterned human microvascular grafts enable rapid vascularization and increase perfusion in infarcted rat hearts
Nature Communications, 2019Co-Authors: Meredith A Redd, Ruikang K. Wang, Wei Wei, Wan Qin, Charles E Murry, Nicole Zeinstra, Amy M Martinson, Yuliang Wang, Ying ZhengAbstract:Vascularization and efficient perfusion are long-standing challenges in cardiac tissue engineering. Here we report engineered perfusable microvascular constructs, wherein human embryonic stem cell-derived endothelial cells (hESC-ECs) are seeded both into patterned microchannels and the surrounding collagen matrix. In vitro, the hESC-ECs lining the luminal walls readily sprout and anastomose with de novo-formed endothelial tubes in the matrix under flow. When implanted on infarcted rat hearts, the perfusable microvessel grafts integrate with coronary vasculature to a greater degree than non-perfusable self-assembled constructs at 5 days post-implantation. Optical Microangiography imaging reveal that perfusable grafts have 6-fold greater vascular density, 2.5-fold higher vascular velocities and >20-fold higher volumetric perfusion rates. Implantation of perfusable grafts containing additional hESC-derived cardiomyocytes show higher cardiomyocyte and vascular density. Thus, pre-patterned vascular networks enhance vascular remodeling and accelerate coronary perfusion, potentially supporting cardiac tissues after implantation. These findings should facilitate the next generation of cardiac tissue engineering design.
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optical coherence tomography Microangiography imaging of circumscribed choroidal hemangioma
Ophthalmic Surgery and Lasers, 2018Co-Authors: Adam R Sweeney, Ruikang K. Wang, Qinqin Zhang, Kasra A RezaeiAbstract:Optical coherence tomography angiography (OCTA) is a new imaging technology capable of providing three-dimensional (3-D) retinal and choroidal microvascular maps without a need for exogenous dye. In this study, the authors evaluate the retinal and choroidal microvascular architecture of the macula in a patient with choroidal hemangioma using OCTA. Widefield OCTA with tracking capability and segmentation was performed to provide images with a field of view at 9 × 9 mm2. The en face maximum projection was used to generate 2-D angiograms of different layers with color-coded images. Variable levels of perfusion within the lesion were identified, which correlate well with the known vascular abnormalities of choroidal hemangiomas. OCTA demonstrated an accurate modality to measure the 3-D borders of this lesion. This is the novel utilization of OCTA imaging on choroidal hemangioma. OCTA may provide detailed vascular findings in circumscribed choroidal hemangiomas, which may aid in the diagnosis and evaluation of the treatment response. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:134-137.].
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association between oct based Microangiography perfusion indices and diabetic retinopathy severity
British Journal of Ophthalmology, 2017Co-Authors: Alexander Lin, Kasra A Rezaei, James L Kinyoun, Qinqin Zhang, Ruikang K. Wang, Aaron Y Lee, Cecilia S LeeAbstract:Aim To evaluate the association between retinal capillary non-perfusion and diabetic retinopathy (DR) severity using optical coherence tomography-based Microangiography (OMAG). Methods 33 patients (51 eyes) with a history of diabetes underwent imaging with a 68 kHz Cirrus-5000 spectral domain OMAG prototype. Demographic and clinical characteristics were collected. The perfusion index (PI) was defined as per cent coverage of area by retinal vessels with flow, measured within a minimum of 6.8×6.8 mm 2 OMAG scan. The PI in each ETDRS zone was analysed using an automated algorithm. Univariate and multivariate analyses were used to determine the degree of association between PI and DR severity. Results 51 eyes with different DR severities were imaged. More severe DR was significantly associated with lower PI after adjusting for logarithm of the minimum angle of resolution best-corrected visual acuity, hyperlipidaemia, diabetes type and ETDRS ring in a multivariate mixed linear model. Compared with the none–mild non-proliferative diabetic retinopathy (NPDR) group, the moderate–severe NPDR group had 2.7 lower PI (p=0.03) and proliferative DR group had 4.3 lower PI (p=0.003). All ETDRS zones except for the foveal centre showed inverse associations between PI and DR severity (p values Conclusions A statistically significant inverse association exists between PI and DR severity. Our study suggests that PI may become a useful biomarker in evaluating and following the progression of DR.
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repeatability of vessel density measurement in human skin by oct based Microangiography
Skin Research and Technology, 2017Co-Authors: Shaojie Men, Wei Wei, Shaozhen Song, C L Chen, T Y Lai, Ruikang K. WangAbstract:PURPOSE To investigate the repeatability of vessel density measurement at human arm skin in healthy subjects with OCT-based Microangiography (OMAG). METHODS Four locations including volar wrist, volar forearm, shoulder, and volar upper arm were scanned using an optimized swept source OCT system, working at center wavelength of 1300 nm and A-line rate of 100 kHz. Three scans were acquired at each location at the same visit. Vascular images of papillary dermis, reticular dermis, and the whole dermis layer were generated with OMAG processing and automatic segmentation algorithms. The vessel density (VD) of each layer was calculated based on vascular images, and the repeatability of the VD at the same physiological location was thereafter assessed. RESULTS Fifteen healthy volunteers were included. High repeatability of VD was found for wrist, forearm, shoulder, and upper arm (coefficient of variation (CV)=2.4, 2.7, 2.7, 2.0, and intraclass correlation coefficient (ICC)=0.906, 0.854, 0.943, 0.916 respectively). The VD measurements showed no significant difference between the four locations in any of the three layers, ie papillary layer (P=.1063), reticular layer (P=.3371), and whole dermis layer (P=.3233). CONCLUSION Quantification of VD by using OCT/OMAG is repeatable when imaging skin tissue beds in healthy individuals.
Utku Baran - One of the best experts on this subject based on the ideXlab platform.
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potential use of oct based Microangiography in clinical dermatology
Skin Research and Technology, 2016Co-Authors: Utku Baran, Woo June Choi, Ruikang K. WangAbstract:Background Optical coherence tomography (OCT) is a revolutionary imaging technique used commonly in ophthalmology, and on the way to become clinically viable alternative in dermatology due to its capability of acquiring histopathology level details of in vivo tissue, non-invasively. In this study, we demonstrate the capabilities of OCT-based Microangiography in detecting high resolution, three-dimensional structural, and microvascular features of in vivo human skin with various conditions. Methods A swept-source OCT system that operates on a central wavelength of 1310 nm with an A-line rate of 100 kHz is used in this study. We apply optical Microangiography (OMAG) technique to visualize the structural and microvascular changes in tissue. Results OMAG images provide detailed visualization of functional microvasculature of healthy human skin from cheek and forehead areas, abnormal skin conditions from face, chest and belly. Moreover, OMAG is capable of monitoring the progress of wound healing on human skin from arm, delivering unprecedented detail of microstructural and microvascular information during longitudinal wound healing process. Conclusion The presented results promise the clinical use of OCT angiography, aiming to treat prevalent cutaneous diseases, by detecting blood perfusion, and structural changes within human skin, in vivo.
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optical coherence tomography based Microangiography a tool good for dermatology applications conference presentation
Proceedings of SPIE, 2016Co-Authors: Ruikang K. Wang, Utku Baran, Woo June ChoiAbstract:Optical coherence tomography (OCT) based Microangiography (OMAG) is a new imaging technique enabling the visualization of blood flow within microcirculatory tissue beds in vivo with high resolution. In this talk, the concept and advantages of OMAG will be discussed and its potential clinical applications in the dermatology will be shown, demonstrating its usefulness in the clinical monitoring and therapeutic treatment of various skin pathologies, e.g. acne, port wine stain and wound healing.
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video rate volumetric optical coherence tomography based Microangiography
Optical Engineering, 2016Co-Authors: Utku Baran, Wei Wei, Wyatt O Davis, Ruikang K. WangAbstract:Video-rate volumetric optical coherence tomography (vOCT) is relatively young in the field of OCT imaging but has great potential in biomedical applications. Due to the recent development of the MHz range swept laser sources, vOCT has started to gain attention in the community. Here, we report the first in vivo video-rate volumetric OCT-based Microangiography (vOMAG) system by integrating an 18-kHz resonant microelectromechanical system (MEMS) mirror with a 1.6-MHz FDML swept source operating at ∼ 1.3 μ m wavelength. Because the MEMS scanner can offer an effective B-frame rate of 36 kHz, we are able to engineer vOMAG with a video rate up to 25 Hz. This system was utilized for real-time volumetric in vivo visualization of cerebral microvasculature in mice. Moreover, we monitored the blood perfusion dynamics during stimulation within mouse ear in vivo . We also discussed this system’s limitations. Prospective MEMS-enabled OCT probes with a real-time volumetric functional imaging capability can have a significant impact on endoscopic imaging and image-guided surgery applications.
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application of optical coherence tomography based Microangiography for cerebral imaging
Proceedings of SPIE, 2016Co-Authors: Utku Baran, Ruikang K. WangAbstract:Requirements of in vivo rodent brain imaging are hard to satisfy using traditional technologies such as magnetic resonance imaging and two-photon microscopy. Optical coherence tomography (OCT) is an emerging tool that can easily reach at high speeds and provide high resolution volumetric images with a relatively large field of view for rodent brain imaging. Here, we provide the overview of recent developments of functional OCT based imaging techniques for neuroscience applications on rodents. Moreover, a summary of OCT-based Microangiography (OMAG) studies for stroke and traumatic brain injury cases on rodents are provided.
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intervolume analysis to achieve four dimensional optical Microangiography for observation of dynamic blood flow
Journal of Biomedical Optics, 2016Co-Authors: Wei Wei, Utku Baran, Shaozhen Song, Wan Qin, Ruikang K. WangAbstract:We demonstrate in vivo volumetric optical Microangiography at ∼ 200 volumes/s by the use of 1.6 MHz Fourier domain mode-locking swept source optical coherence tomography and an effective 36 kHz microelectromechanical system (MEMS) scanner. We propose an intervolume analysis strategy to contrast the dynamic blood flow signal from the static tissue background. The proposed system is demonstrated by imaging cerebral blood flow in mice in vivo. For the first time, imaging speed, sensitivity, and temporal resolution become possible for a direct four-dimensional observation of microcirculations within live body parts.
Zhongwei Zhi - One of the best experts on this subject based on the ideXlab platform.
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optical coherence tomography based Microangiography for quantitative monitoring of structural and vascular changes in a rat model of acute uveitis in vivo a preliminary study
Journal of Biomedical Optics, 2015Co-Authors: Woo June Choi, Kathryn L Pepple, Zhongwei Zhi, Ruikang K. WangAbstract:Uveitis models in rodents are important in the investigation of pathogenesis in human uveitis and the development of appropriate therapeutic strategies for treatment. Quantitative monitoring of ocular inflammation in small animal models provides an objective metric to assess uveitis progression and/or therapeutic effects. We present a new application of optical coherence tomography (OCT) and OCT-based Microangiography (OMAG) to a rat model of acute anterior uveitis induced by intravitreal injection of a killed mycobacterial extract. OCT/OMAG is used to provide noninvasive three-dimensional imaging of the anterior segment of the eyes prior to injection (baseline) and two days post-injection (peak inflammation) in rats with and without steroid treatments. OCT imaging identifies characteristic structural and vascular changes in the anterior segment of the inflamed animals when compared to baseline images. Characteristics of inflammation identified include anterior chamber cells, corneal edema, pupillary membranes, and iris vasodilation. In contrast, no significant difference from the control is observed for the steroid-treated eye. These findings are compared with the histology assessment of the same eyes. In addition, quantitative measurements of central corneal thickness and iris vessel diameter are determined. This pilot study demonstrates that OCT-based Microangiography promises to be a useful tool for the assessment and management of uveitis in vivo.
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In vivo OCT Microangiography of rodent iris.
Optics letters, 2014Co-Authors: Woo June Choi, Zhongwei Zhi, Ruikang K. WangAbstract:We report on the functional optical coherence tomography (OCT) imaging of iris tissue morphology and microcirculation in living small animals. Anterior segments of healthy mouse and rat eyes are imaged with high-speed spectral domain OCT (SD-OCT) utilizing ultrahigh sensitive optical Microangiography (UHS-OMAG) imaging protocol. 3D iris microvasculature is produced by the use of an algorithm that calculates absolute differences between the amplitudes of the OCT interframes. We demonstrate that the UHS-OMAG is capable of delineating iris microvascular beds in the mouse and rat with capillary-level resolution. Furthermore, the fast imaging speed enables dynamic imaging of iris micro-vascular response during drug-induced pupil dilation. We believe that this OCT angiographic approach has a great potential for in situ and in vivo monitoring of the microcirculation within iris tissue beds in rodent disease models that have microvascular involvement.
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changes in cochlear blood flow in mice due to loud sound exposure measured with doppler optical Microangiography and laser doppler flowmetry
Quantitative imaging in medicine and surgery, 2013Co-Authors: Roberto Reif, Suzan Dziennis, Zhongwei Zhi, Alfred L Nuttall, Ruikang K. WangAbstract:In this work we determined the contributions of loud sound exposure (LSE) on cochlear blood flow (CoBF) in an in vivo anesthetized mouse model. A broadband noise system (20 kHz bandwidth) with an intensity of 119 dB SPL, was used for a period of one hour to produce a loud sound stimulus. Two techniques were used to study the changes in blood flow, a Doppler optical Microangiography (DOMAG) system; which can measure the blood flow within individual cochlear vessels, and a laser Doppler flowmetry (LDF) system; which averages the blood flow within a volume (a hemisphere of ~1.5 mm radius) of tissue. Both systems determined that the blood flow within the cochlea is reduced due to the LSE stimulation.
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tracking dynamic microvascular changes during healing after complete biopsy punch on the mouse pinna using optical Microangiography
PLOS ONE, 2013Co-Authors: Yeongri Jung, Suzan Dziennis, Zhongwei Zhi, Roberto Reif, Ying Zheng, Ruikang K. WangAbstract:Optical Microangiography (OMAG) and Doppler optical Microangiography (DOMAG) are two non-invasive techniques capable of determining the tissue microstructural content, microvasculature angiography, and blood flow velocity and direction. These techniques were used to visualize the acute and chronic microvascular and tissue responses upon an injury in vivo. A tissue wound was induced using a 0.5 mm biopsy punch on a mouse pinna. The changes in the Microangiography, blood flow velocity and direction were quantified for the acute (<30 min) wound response and the changes in the tissue structure and Microangiography were determined for the chronic wound response (30 min–60 days). The initial wound triggered recruitment of peripheral capillaries, as well as redirection of main arterial and venous blood flow within 3 min. The complex vascular networks and new vessel formation were quantified during the chronic response using fractal dimension. The highest rate of wound closure occurred between days 8 and 22. The vessel tortuosity increased during this time suggesting angiogenesis. Taken together, these data signify that OMAG has the capability to track acute and chronic changes in blood flow, Microangiography and structure during wound healing. The use of OMAG has great potential to improve our understanding of vascular and tissue responses to injury in order to develop more effective therapeutics.
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hemodynamic and morphological vasculature response to a burn monitored using a combined dual wavelength laser speckle and optical Microangiography imaging system
Biomedical Optics Express, 2012Co-Authors: Jia Qin, Suzan Dziennis, Zhongwei Zhi, Roberto Reif, Ruikang K. WangAbstract:A multi-functional imaging system capable of determining relative changes in blood flow, hemoglobin concentration, and morphological features of the blood vasculature is demonstrated. The system combines two non-invasive imaging techniques, a dual-wavelength laser speckle contrast imaging (2-LSI) and an optical Microangiography (OMAG) system. 2-LSI is used to monitor the changes in the dynamic blood flow and the changes in the concentration of oxygenated (HbO), deoxygenated (Hb) and total hemoglobin (HbT). The OMAG system is used to acquire high resolution images of the functional blood vessel network. The vessel area density (VAD) is used to quantify the blood vessel network morphology, specifically the capillary recruitment. The proposed multi-functional system is employed to assess the blood perfusion status from a mouse pinna before and immediately after a burn injury. To our knowledge, this is the first non-invasive, non-contact and multifunctional imaging modality that can simultaneously measure variations of several blood perfusion parameters.
Woo June Choi - One of the best experts on this subject based on the ideXlab platform.
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using oct based Microangiography for in vivo longitudinal study of arteriogenesis conference presentation
Proceedings of SPIE, 2017Co-Authors: Woo June Choi, Ruikang K. WangAbstract:The adaptive growth of collateral vessels, termed “arteriogenesis”, is crucial for maintaining regional blood supply during arterial obstruction and offsetting the adverse effect of tissue ischemia. Stimulation of arteriogenesis has been applied for the treatment of occlusive vascular diseases, and in vivo imaging of the progressive development of collateral vessel will facilitate a better understanding of the mechanism. We present using high-resolution OCT-based Microangiography (OMAG) to image arteriogenesis process longitudinally in mouse cerebral cortex after middle cerebral artery occlusion (MCAO). We imaged the collateral arterioles at the arteriolo-arteriolar anastomosis (AAA) within 7-day period after MCAO to reveal key elements of collateral vessel remodeling, including alteration in vessel morphology, velocity and directionality of blood flow. The magnitudes of changes in these parameters matched the time course of the active building of collateral vessels stated in previous studies using histology. Hence, OMAG is a promising imaging tool for non-invasive longitudinal study of functional collateral vessel growth in small animal models and can be potentially applied in the experimental study of arteriogenesis stimulation.
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characterization of relationship between optical Microangiography omag signal and blood flow conference presentation
Proceedings of SPIE, 2017Co-Authors: Woo June Choi, Chiehli Chen, Qinqin Zhang, Jingang Wang, Wan Qin, Ruikang K. WangAbstract:Optical Microangiography (OMAG) is a powerful optical angiographic tool to visualize micro-vascular flow in vivo. Despite numerous demonstrations for the past several years of the qualitative relationship between OMAG and flow, no convincing quantitative relationship has been proven. In this paper, we attempt to quantitatively correlate the OMAG signal with flow. Specifically, we develop a simplified analytical model of the complex OMAG, suggesting that the OMAG signal is a product of the number of particles in an imaging voxel and the decorrelation of OCT (optical coherence tomography) signal, determined by flow velocity, interframe time interval, and wavelength of the light source. Numerical simulation with the proposed model reveals that if the OCT amplitudes are correlated, the OMAG signal is related to a total number of particles across the imaging voxel cross-section per unit time (flux); otherwise it would be saturated but its strength is proportional to the number of particles in the imaging voxel (concentration). The relationship is validated using microfluidic flow phantoms with various preset flow metrics. This work suggests OMAG is a promising quantitative tool for the assessment of vascular flow.
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characterizing relationship between optical Microangiography signals and capillary flow using microfluidic channels
Biomedical Optics Express, 2016Co-Authors: Woo June Choi, Chiehli Chen, Qinqin Zhang, Jingang Wang, Wan Qin, Xiaoqi Yang, Bruce Z Gao, Ruikang K. WangAbstract:Optical Microangiography (OMAG) is a powerful optical angio-graphic tool to visualize micro-vascular flow in vivo. Despite numerous demonstrations for the past several years of the qualitative relationship between OMAG and flow, no convincing quantitative relationship has been proven. In this paper, we attempt to quantitatively correlate the OMAG signal with flow. Specifically, we develop a simplified analytical model of the complex OMAG, suggesting that the OMAG signal is a product of the number of particles in an imaging voxel and the decorrelation of OCT (optical coherence tomography) signal, determined by flow velocity, inter-frame time interval, and wavelength of the light source. Numerical simulation with the proposed model reveals that if the OCT amplitudes are correlated, the OMAG signal is related to a total number of particles across the imaging voxel cross-section per unit time (flux); otherwise it would be saturated but its strength is proportional to the number of particles in the imaging voxel (concentration). The relationship is validated using microfluidic flow phantoms with various preset flow metrics. This work suggests OMAG is a promising quantitative tool for the assessment of vascular flow.
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potential use of oct based Microangiography in clinical dermatology
Skin Research and Technology, 2016Co-Authors: Utku Baran, Woo June Choi, Ruikang K. WangAbstract:Background Optical coherence tomography (OCT) is a revolutionary imaging technique used commonly in ophthalmology, and on the way to become clinically viable alternative in dermatology due to its capability of acquiring histopathology level details of in vivo tissue, non-invasively. In this study, we demonstrate the capabilities of OCT-based Microangiography in detecting high resolution, three-dimensional structural, and microvascular features of in vivo human skin with various conditions. Methods A swept-source OCT system that operates on a central wavelength of 1310 nm with an A-line rate of 100 kHz is used in this study. We apply optical Microangiography (OMAG) technique to visualize the structural and microvascular changes in tissue. Results OMAG images provide detailed visualization of functional microvasculature of healthy human skin from cheek and forehead areas, abnormal skin conditions from face, chest and belly. Moreover, OMAG is capable of monitoring the progress of wound healing on human skin from arm, delivering unprecedented detail of microstructural and microvascular information during longitudinal wound healing process. Conclusion The presented results promise the clinical use of OCT angiography, aiming to treat prevalent cutaneous diseases, by detecting blood perfusion, and structural changes within human skin, in vivo.
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optical coherence tomography based Microangiography a tool good for dermatology applications conference presentation
Proceedings of SPIE, 2016Co-Authors: Ruikang K. Wang, Utku Baran, Woo June ChoiAbstract:Optical coherence tomography (OCT) based Microangiography (OMAG) is a new imaging technique enabling the visualization of blood flow within microcirculatory tissue beds in vivo with high resolution. In this talk, the concept and advantages of OMAG will be discussed and its potential clinical applications in the dermatology will be shown, demonstrating its usefulness in the clinical monitoring and therapeutic treatment of various skin pathologies, e.g. acne, port wine stain and wound healing.
Qinqin Zhang - One of the best experts on this subject based on the ideXlab platform.
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visualization of oct signal pulsatility at variable tissue depth with optical Microangiography
Dynamics and Fluctuations in Biomedical Photonics XVII, 2020Co-Authors: Zhiying Xie, Qinqin Zhang, Yuxuan Cheng, Geng Wang, Ruikang K. WangAbstract:Pulsatile signals from the cutaneous blood flow could be informative for evaluating the health condition of an individual. One of the popular optical measuring devices, photoplethysmogram (PPG) is often used to detect the pulse signal from skin. However, the origin of the PPG signal still remains controversial. Benefiting from the non-invasive, label-free, 3D imaging tool, optical coherence tomography (OCT) is able to capture the intrinsic tissue signals at different penetration depth in high spatial and temporal resolution. Periodic pulse signal was observed by taking advantage of the optical Microangiography (OMAG) algorithm which is sensitive to the motion of blood flow. The pulsatile pattern from the capillary and arteriole was successfully differentiated and their morphology showed distinct property at different local blood pressure. The pulse signal from the arteriole is more consistent and has similar waveform as the PPG signals. The result indicated that the PPG signal could be deceive by the mixing signal from the capillary bed and arterioles since it measures the total blood volume change in the plexuses. This study may shed some new light on understanding the mechanical property of how blood travel through different types of vasculature networks and elucidate its potential application in disease assessments.
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optical coherence tomography Microangiography imaging of circumscribed choroidal hemangioma
Ophthalmic Surgery and Lasers, 2018Co-Authors: Adam R Sweeney, Ruikang K. Wang, Qinqin Zhang, Kasra A RezaeiAbstract:Optical coherence tomography angiography (OCTA) is a new imaging technology capable of providing three-dimensional (3-D) retinal and choroidal microvascular maps without a need for exogenous dye. In this study, the authors evaluate the retinal and choroidal microvascular architecture of the macula in a patient with choroidal hemangioma using OCTA. Widefield OCTA with tracking capability and segmentation was performed to provide images with a field of view at 9 × 9 mm2. The en face maximum projection was used to generate 2-D angiograms of different layers with color-coded images. Variable levels of perfusion within the lesion were identified, which correlate well with the known vascular abnormalities of choroidal hemangiomas. OCTA demonstrated an accurate modality to measure the 3-D borders of this lesion. This is the novel utilization of OCTA imaging on choroidal hemangioma. OCTA may provide detailed vascular findings in circumscribed choroidal hemangiomas, which may aid in the diagnosis and evaluation of the treatment response. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:134-137.].
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association between oct based Microangiography perfusion indices and diabetic retinopathy severity
British Journal of Ophthalmology, 2017Co-Authors: Alexander Lin, Kasra A Rezaei, James L Kinyoun, Qinqin Zhang, Ruikang K. Wang, Aaron Y Lee, Cecilia S LeeAbstract:Aim To evaluate the association between retinal capillary non-perfusion and diabetic retinopathy (DR) severity using optical coherence tomography-based Microangiography (OMAG). Methods 33 patients (51 eyes) with a history of diabetes underwent imaging with a 68 kHz Cirrus-5000 spectral domain OMAG prototype. Demographic and clinical characteristics were collected. The perfusion index (PI) was defined as per cent coverage of area by retinal vessels with flow, measured within a minimum of 6.8×6.8 mm 2 OMAG scan. The PI in each ETDRS zone was analysed using an automated algorithm. Univariate and multivariate analyses were used to determine the degree of association between PI and DR severity. Results 51 eyes with different DR severities were imaged. More severe DR was significantly associated with lower PI after adjusting for logarithm of the minimum angle of resolution best-corrected visual acuity, hyperlipidaemia, diabetes type and ETDRS ring in a multivariate mixed linear model. Compared with the none–mild non-proliferative diabetic retinopathy (NPDR) group, the moderate–severe NPDR group had 2.7 lower PI (p=0.03) and proliferative DR group had 4.3 lower PI (p=0.003). All ETDRS zones except for the foveal centre showed inverse associations between PI and DR severity (p values Conclusions A statistically significant inverse association exists between PI and DR severity. Our study suggests that PI may become a useful biomarker in evaluating and following the progression of DR.
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peripapillary retinal nerve fiber layer vascular microcirculation in eyes with glaucoma and single hemifield visual field loss
JAMA Ophthalmology, 2017Co-Authors: Chiehli Chen, Qinqin Zhang, Karine D Bojikian, Raghu C Mudumbai, Murray A Johnstone, Philip P Chen, Joanne C Wen, Chen Xin, Ruikang K. WangAbstract:Importance Understanding the differences in vascular microcirculation of the peripapillary retinal nerve fiber layer (RNFL) between the hemispheres in eyes with glaucoma with single-hemifield visual field (VF) defects may provide insight into the pathophysiology of glaucoma. Objective To investigate the changes in the microcirculation of the peripapillary RNFL of eyes with glaucoma by using optical Microangiography. Design, Setting, and Participants Eyes with glaucoma and single-hemifield VF defect and normal eyes underwent scanning using an optical Microangiography system covering a 6.7 × 6.7-mm 2 area centered at the optic nerve head. The RNFL microcirculation was measured within an annulus region centered at the optic nerve head divided into superior and inferior hemispheres. Blood flux index (the mean flow signal intensity in the vessels) and vessel area density (the percentage of the detected vessels in the annulus) were measured. Main Outcomes and Measures Differences in microcirculation between the hemispheres in eyes with glaucoma and normal eyes and correlations among blood flow metrics, VF thresholds, and clinical optical coherence tomography structural measurements were assessed. Results Twenty-one eyes from 21 patients with glaucoma (7 men and 14 women; mean [SD] age, 63.7 [9.9] years) and 20 eyes from 20 healthy control individuals (9 men and 11 women; mean [SD] age, 68.3 [10.7] years) were studied. In eyes with glaucoma, the abnormal hemisphere showed a thinner RNFL (mean [SE] difference, 23.5 [4.5] μm; 95% CI, 15.1-32.0 µm; P P P P P = .003) but not in RNFL thickness (3.4 [4.7] μm; 95% CI, −6.2 to 12.9 µm; P = .48). Strong correlations were found between the blood flux index and VF mean deviation (Spearman ρ = 0.44; P = .045) and RNFL thickness (Spearman ρ = 0.65; P = .001) in the normal hemisphere of the eye with glaucoma. Conclusions and Relevance Reduced RNFL microcirculation was detected in the normal hemisphere of eyes with glaucoma, with strong correspondence with VF loss and RNFL thinning. Although the results suggest that vascular dysfunction precedes structural changes seen in glaucoma, longitudinal studies would be needed to confirm this finding.
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characterization of relationship between optical Microangiography omag signal and blood flow conference presentation
Proceedings of SPIE, 2017Co-Authors: Woo June Choi, Chiehli Chen, Qinqin Zhang, Jingang Wang, Wan Qin, Ruikang K. WangAbstract:Optical Microangiography (OMAG) is a powerful optical angiographic tool to visualize micro-vascular flow in vivo. Despite numerous demonstrations for the past several years of the qualitative relationship between OMAG and flow, no convincing quantitative relationship has been proven. In this paper, we attempt to quantitatively correlate the OMAG signal with flow. Specifically, we develop a simplified analytical model of the complex OMAG, suggesting that the OMAG signal is a product of the number of particles in an imaging voxel and the decorrelation of OCT (optical coherence tomography) signal, determined by flow velocity, interframe time interval, and wavelength of the light source. Numerical simulation with the proposed model reveals that if the OCT amplitudes are correlated, the OMAG signal is related to a total number of particles across the imaging voxel cross-section per unit time (flux); otherwise it would be saturated but its strength is proportional to the number of particles in the imaging voxel (concentration). The relationship is validated using microfluidic flow phantoms with various preset flow metrics. This work suggests OMAG is a promising quantitative tool for the assessment of vascular flow.