1. Articles from xiangqun xu

    1-17 of 17
    1. Assessment of blood coagulation using an acoustic radiation force based optical coherence elastography (ARF-OCE)

      Assessment of blood coagulation using an acoustic radiation force based optical coherence elastography (ARF-OCE)

      An apparatus and method of using an optical coherence elastography (OCE) under acoustic radiation force (ARF) excitation includes the steps of inducing an excitation wave in a blood sample by use of an ultrasound beam from an ultrasonic transducer; measuring an elastic property of the blood sample by use of an optical coherence tomography (OCT) beam transverse to the ultrasound beam to dynamically measure the elastic property of the blood sample during coagulation and assessing the clot formation/dissolution kinetics and strength.

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    2. Viscosity monitoring during hemodiluted blood coagulation using optical coherence elastography

      Viscosity monitoring during hemodiluted blood coagulation using optical coherence elastography

      Rapid and accurate clot diagnostic systems are needed for the assessment of hemodiluted blood coagulation. We develop a real-time optical coherence elastography (OCE) system, which measures the attenuation coefficient of a compressional wave induced by a piezoelectric transducer (PZT) in a drop of blood using optical coherence tomography (OCT), for the determination of viscous properties during the dynamic whole blood coagulation process. Changes in the viscous properties increase the attenuation coefficient of the sample. Consequently, dynamic blood coagulation status can be monitored by relating changes of the attenuation coefficient to clinically relevant coagulation metrics, including the initial coagulation time and ...

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    3. Coagulation monitoring based on blood elastic measurement using optical coherence tomography

      Coagulation monitoring based on blood elastic measurement using optical coherence tomography

      Blood coagulation monitoring is important to diagnose hematological diseases and cardiovascular diseases and to predict the risk of bleeding and excessive clotting. In this study, we developed a system to dynamically monitor blood coagulation and quantitatively determine the coagulation function by blood elastic measurement. When blood forms a clot from a liquid, ultrasonic force induces a shear wave, which is detected by optical coherence tomography (OCT). The coagulation of porcine whole blood recalcified by calcium chloride is assessed using the metrics of reaction time, clot formation kinetics and maximum shear modulus. The OCE system can noninvasively monitor the blood coagulation ...

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    4. Dynamic and quantitative assessment of blood coagulation using optical coherence elastography

      Dynamic and quantitative assessment of blood coagulation using optical coherence elastography

      Reliable clot diagnostic systems are needed for directing treatment in a broad spectrum of cardiovascular diseases and coagulopathy. Here, we report on non-contact measurement of elastic modulus for dynamic and quantitative assessment of whole blood coagulation using acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE). In this system, acoustic radiation force (ARF) is produced by a remote ultrasonic transducer, and a shear wave induced by ARF excitation is detected by the optical coherence tomography (OCT) system. During porcine whole blood coagulation, changes in the elastic property of the clots increase the shear modulus of the sample, altering the propagating ...

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    5. Effect of fibrinogen on blood coagulation detected by optical coherence tomography

      Effect of fibrinogen on blood coagulation detected by optical coherence tomography

      Our previous work demonstrated that an optical coherence tomography (OCT) technique and the parameter 1/ e light penetration depth ( d 1/ e ) were able to characterize the whole blood coagulation process in contrast to existing optical tests that are performed on plasma samples. To evaluate the feasibility of the technique for quantifying the effect of fibrinogen (Fbg) on blood coagulation, a dynamic study of d 1/ e of blood in various Fbg concentrations was performed in static state. Two groups of blood samples of hematocrit (HCT) in 35, 45, and 55% were reconstituted of red blood cells with: 1) treated ...

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    6. Monitoring the blood coagulation process under various flow conditions with optical coherence tomography

      Monitoring the blood coagulation process under various flow conditions with optical coherence tomography

      Our previous work demonstrated that an optical coherence tomography (OCT) technique was able to characterize the whole blood coagulation process. The 1 / e light penetration depth ( d 1 / e ) derived from the profiles of reflectance versus depth was developed for detecting the whole blood coagulation process in static state. To consider the effect of blood flow, in the present study, d 1 / e versus time from the coagulating porcine blood circulated in a mock flow loop with various steady laminar flows at mean flow speed in the range from 5 to 25     mm / s . The variation of d 1 / e ...

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    7. Evaluation of optical coherence tomography for the measurement of the effects of activators and anticoagulants on the blood coagulation in vitro

      Evaluation of optical coherence tomography for the measurement of the effects of activators and anticoagulants on the blood coagulation in vitro

      Optical properties of human blood during coagulation was studied using optical coherence tomography (OCT) and the parameter of clotting time derived from the 1/e light penetration depth (d1/e) vs. time was developed in our previous work. In this study, in order to know if a new optical coherence tomography test can characterize the blood coagulation process under different treatments in vitro, the effects of two different activators (calcium ions and thrombin) and anticoagulants, i.e., acetylsalicylic acid (ASA, a well-known drug aspirin) and melagatran (a direct thrombin inhibitor), at various concentrations are evaluated. A swept source OCT system ...

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    8. Characterization of flowing blood optical property under various fibrinogen levels using optical coherence tomography

      Characterization of flowing blood optical property under various fibrinogen levels using optical coherence tomography

      The feasibility of characterization of human blood fibrinogen levels using optical coherence tomography (OCT) was investigated. Three groups of blood samples were reconstituted of red blood cells and, I. phosphate buffered saline, II. plasma with its intrinsic fibrinogen removed and commercial fibrinogen added, III. native plasma with various fibrinogen levels (0-12 g/L). OCT signal slope (OCTSS) of blood was extracted from OCT depth-reflectivity profiles. Effects of hematocrit (HCT) and blood flow on OCTSS of the blood under various fibrinogen concentrations were also studied. The results of blood flowing at 5 mm/sec showed that OCTSS of all the three ...

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    9. Optical coherence tomography to investigate optical properties of blood during coagulation

      Optical coherence tomography to investigate optical properties of blood during coagulation
      This study investigates the optical properties of human blood during the coagulation process under statics using optical coherence tomography (OCT). OCT signal slope (OCTSS) and 1/e light penetration depth (d1/e) were obtained from the profiles of reflectance versus depth. Results showed that both OCTSS and d1/e were able to sensitively differentiate various stages of blood properties during coagulating. After 1 h clotting, OCTSS decreased by 47.0%, 15.0%, 13.7%, and 8.5% and d1/e increased by 34.7%, 29.4%, 24.3%, and 22.9% for the blood samples at HCT of 25%, 35 ...
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    10. Evaluation of whole blood coagulation process by optical coherence tomography

      Evaluation of whole blood coagulation process by optical coherence tomography
      This study was to investigate the feasibility of using optical coherence tomography (OCT) to evaluate whole blood coagulation process. Attenuation coefficients and 1/e light penetration depth (D1/e) against time of human whole blood during in vitro clot formation under static were measured from the OCT profiles of reflectance vs depth. The results obtained clearly showed that the optical parameters are able to identify three stages during the in vitro blood clotting process. It is concluded that D1/e measured by OCT is a potential parameter to quantify and follow the liquid-gel transition of blood during clotting.
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    11. Velocity Variation Assessment of Red Blood Cell Aggregation with Spectral Domain Doppler Optical Coherence Tomography

      Velocity Variation Assessment of Red Blood Cell Aggregation with Spectral Domain Doppler Optical Coherence Tomography
      We propose spectral domain Doppler optical coherence tomography (SD-D-OCT) to qualitatively measure red blood cell aggregation. Variance/standard deviation (SD) of the Doppler frequency spectrum in Doppler variance imaging of flowing blood under shearing conditions was developed as a new aggregation index. In in vitro microchannel-flow experiments, porcine blood at various hematocrits with aggregation characteristics induced by dextran 500 or at the presence of plasma fibrinogen was measured by a SD-D-OCT system with a spectrum centered at 1310 nm. The effects of shear rate, hematocrit, aggregation level on the SD values were investigated. The results demonstrate that Doppler variance imaging ...
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    12. Assessment of the effects of ultrasound-mediated alcohols on skin optical clearing

      Our previous studies have shown the ultrasound-induced skin optical clearing enhancement with topical application of glycerol on in vitro porcine skin and in vivo human skin. The objective of this study was to find more effective ultrasound-alcohol combinations on skin optical clearing. The effect of sonophoretic delivery (SP) in combination with a series of alcohols such as glycerol, propylene glycol, butanediol, butanol, polyethylene glycol (PEG200, PEG400) on skin optical clearing was investigated. Light transmittance and imaging depth of in vitro porcine skin were measured with spectroscopy and optical coherence tomography (OCT). Sixty percent alcohols and ultrasound (SP) with a frequency ...
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    13. Combined Effect of Ultrasound-SLS on Skin Optical Clearing

      Our previous studies demonstrated the ultrasound-induced skin optical clearing enhancement with topical application of optical clearing agents on in vitro porcine skin and in vivo human skin. The objective of this study was to develop more effective methods by simultaneously using two kinds of skin permeation enhancers. The effect of ultrasound (SP) in combination with a chemical enhancer, sodium lauryl sulfate (SLS), on skin optical clearing was investigated. Light transmittance and imaging depth of in vitro porcine skin were measured with spectroscopy and optical coherence tomography (OCT). Three treatments were performed: 1) 60% glycerol (60% Gly); 2) 60% glycerol $+ $15-min ...
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    14. Skin optical clearing enhancement with penetration enhancer azone using spectroscopy and optical coherence tomography

      In order to find a non-invasive way to improve the efficacy of skin optical clearing with topically applied optical clearing agents (OCA), we evaluated the effect of azone ® (epsilon-Laurocapram) as a chemical penetration enhancer on optical clearing of intact skin in vitro. Fresh porcine skin ... [Proc. SPIE 6791, 67910F (2008)] published Mon Jun 9, 2008.
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    15. Optical clearing of flowing blood using dextrans with spectral domain optical coherence tomography

      Xiangqun Xu, Lingfeng Yu, and Zhongping Chen Spectral domain optical coherence tomography (SDOCT) images have been used to investigate the mechanism of optical clearing in flowing blood using dextrans. The depth reflectivity profiles from SDOCT indicate that dextrans become increasingly more effective in reducing scattering in flowing blood, e ... [J. Biomed. Opt. 13, 021107 (2008)] published Tue Apr 29, 2008.
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    16. Sonophoretic Delivery for Contrast and Depth Improvement in Skin Optical Coherence Tomography

      Our previous studies demonstrated the feasibility of using a sonophoretic delivery method to enhance skin light transmittance with topical application of optical clearing agents using spectroscopy. In this study, we examined the effect of ultrasound [surgeon-performed (SP)] on optical coherence tomography (OCT) imaging depth and contrast of in vitro and in vivo skin. Sixty percent glycerol (G) and SP with a frequency of 1 MHz and a power of 0.75 W over a 3 cm probe was simultaneously applied for 15 min. We find that 60% G/SP results in a twofold increase in achievable OCT imaging depth for ...
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    17. Optical clearing of in vivo human skin with hyperosmotic chemicals investigated by optical coherence tomography and near-infrared reflectance spectroscopy

      Optical clearing of in vivo human skin with hyperosmotic chemicals investigated by optical coherence tomography and near-infrared reflectance spectroscopy
      Although application of clearing agents to skin and other tissues in vitro has been studied, few have led to quantifiable results in vivo human skin. This study was to evaluate the optical clearing of human skin in vivo with topical application of hyperosmotic agents. Optical coherence tomography imaging was used to perform visual assessment of human skin during optical clearing process. Topical application of 80% glycerol and 50% DMSO to palmar skin of volunteers results in an increase in imaging depth and contrast. Imaging depth was increased to 1.1 mm after 15 minute topical treatment. The layers that consist ...
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    1-17 of 17
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    Velocity Variation Assessment of Red Blood Cell Aggregation with Spectral Domain Doppler Optical Coherence Tomography Evaluation of whole blood coagulation process by optical coherence tomography Optical clearing of in vivo human skin with hyperosmotic chemicals investigated by optical coherence tomography and near-infrared reflectance spectroscopy Optical coherence tomography to investigate optical properties of blood during coagulation Characterization of flowing blood optical property under various fibrinogen levels using optical coherence tomography Evaluation of optical coherence tomography for the measurement of the effects of activators and anticoagulants on the blood coagulation in vitro A Generic Framework for Fourier-Domain Optical Coherence Tomography Imaging: Software Architecture and Hardware Implementations Vision-Inspection-Synchronized Dual Optical Coherence Tomography for High-Resolution Real-Time Multidimensional Defect Tracking in Optical Thin Film Industry Relative retinal flow velocity detection using optical coherence tomography angiography imaging Comparison of Optical Flow Ratio and Fractional Flow Ratio in Stent-Treated Arteries Immediately After Percutaneous Coronary Intervention Spaceflight Associated Neuro-Ocular Syndrome (SANS): A Systematic Review and Future Directions Retinal Thickness and Microvascular Pattern in Early Parkinson's Disease