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      Fast pulsatile blood flow measurement in deep tissue through a multimode detection fiber

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          Significance: Noninvasive in vivo fast pulsatile blood flow measurement in deep tissue is important because the blood flow waveform is correlated with physiological parameters, such as blood pressure and elasticity of blood vessels. Compromised blood flow may cause diseases, such as stroke, foot ulcer, and myocardial ischemia. There is great clinical demand for a portable and cost-effective device for noninvasive pulsatile blood flow measurement.

          Aim: A diffuse-optics-based method, diffuse speckle pulsatile flowmetry (DSPF), was developed for fast measurement ( 300    Hz ) of deep tissue blood flow noninvasively. To validate its performance, both a phantom experiment and in vivo demonstration were conducted.

          Approach: Over the past two decades, single-mode fibers have been used as detection fibers in most diffuse-optics-based deep tissue blood flow measurement modalities. We used a multimode (MM) detection fiber with a core size of 200    μ m for diffused speckle pattern detection. A background intensity correction algorithm was implemented for speckle contrast calculation. The MM detection fiber helped to achieve a level of deep tissue blood flow measurement similar to that of conventional modalities, such as diffuse correlation spectroscopy and diffuse speckle contrast analysis, but it increases the measurement rate of blood flow to 300 Hz.

          Results: The design and implementation of the DSPF system were introduced. The theory of the background intensity correction for the diffused speckle pattern detected by the MM fiber was explained. A flow phantom was built for validation of the performance of the DSPF system. An in vivo cuff-induced occlusion experiment was performed to demonstrate the capability of the proposed DSPF system.

          Conclusions: An MM detection fiber can help to achieve fast ( 300    Hz ) pulsatile blood flow measurement in the proposed DSPF method. The cost-effective device and the fiber-based flexible probe increase the usability of the DSPF system significantly.

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          Most cited references 30

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          Pathogenesis of myocardial ischemia-reperfusion injury and rationale for therapy.

          Since the initial description of the phenomenon by Jennings et al 50 years ago, our understanding of the underlying mechanisms of reperfusion injury has grown significantly. Its pathogenesis reflects the confluence of multiple pathways, including ion channels, reactive oxygen species, inflammation, and endothelial dysfunction. The purposes of this review are to examine the current state of understanding of ischemia-reperfusion injury, as well as to highlight recent interventions aimed at this heretofore elusive target. In conclusion, despite its complexity our ongoing efforts to mitigate this form of injury should not be deterred, because nearly 2 million patients annually undergo either spontaneous (in the form of acute myocardial infarction) or iatrogenic (in the context of cardioplegic arrest) ischemia-reperfusion. Copyright (c) 2010 Elsevier Inc. All rights reserved.
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            Laser speckle contrast analysis (LASCA): a nonscanning, full-field technique for monitoring capillary blood flow.

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              Failure of collateral blood flow is associated with infarct growth in ischemic stroke.

              Changes in collateral blood flow, which sustains brain viability distal to arterial occlusion, may impact infarct evolution but have not previously been demonstrated in humans. We correlated leptomeningeal collateral flow, assessed using novel perfusion magnetic resonance imaging (MRI) processing at baseline and 3 to 5 days, with simultaneous assessment of perfusion parameters. Perfusion raw data were averaged across three consecutive slices to increase leptomeningeal collateral vessel continuity after subtraction of baseline signal analogous to digital subtraction angiography. Changes in collateral quality, Tmax hypoperfusion severity, and infarct growth were assessed between baseline and days 3 to 5 perfusion-diffusion MRI. Acute MRI was analysed for 88 patients imaged 3 to 6 hours after ischemic stroke onset. Better collateral flow at baseline was associated with larger perfusion-diffusion mismatch (Spearman's Rho 0.51, P<0.001) and smaller baseline diffusion lesion volume (Rho -0.70, P<0.001). In 30 patients without reperfusion at day 3 to 5, deterioration in collateral quality between baseline and subacute imaging was strongly associated with absolute (P=0.02) and relative (P<0.001) infarct growth. The deterioration in collateral grade correlated with increased mean Tmax hypoperfusion severity (Rho -0.68, P<0.001). Deterioration in Tmax hypoperfusion severity was also significantly associated with absolute (P=0.003) and relative (P=0.002) infarct growth. Collateral flow is dynamic and failure is associated with infarct growth.

                Author and article information

                J Biomed Opt
                J Biomed Opt
                Journal of Biomedical Optics
                Society of Photo-Optical Instrumentation Engineers
                13 May 2020
                May 2020
                13 May 2020
                : 25
                : 5
                Singapore Bioimaging Consortium , Singapore
                Author notes
                [* ]Address all correspondence to Malini Olivo, E-mail: Malini_Olivo@ 123456sbic.a-star.edu.sg
                JBO-200030R 200030R
                © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
                Page count
                Figures: 6, Tables: 0, References: 39, Pages: 10
                Funded by: Joint Council Office
                Award ID: 1331AFG077
                Funded by: Biomedical Research Council
                Funded by: Agency of Science, Technology and Research (A*STAR)
                Award ID: H19H6a0025
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                Bi et al.: Fast pulsatile blood flow measurement in deep tissue through a multimode detection fiber


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