scholarly journals Dynamic Spatio-Temporal Imaging of Early Reflow in a Neonatal Rat Stroke Model

2012 ◽  
Vol 33 (1) ◽  
pp. 137-145 ◽  
Author(s):  
Pierre-Louis Leger ◽  
Philippe Bonnin ◽  
Pierre Lacombe ◽  
Elisabeth Couture-Lepetit ◽  
Sebastien Fau ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arterial Occlusion ◽  
Tissue Perfusion ◽  
Laser Speckle ◽  
Neonatal Rat ◽  
Immature Rat ◽  
Collateral Pathway ◽  
Flow Changes ◽  
Spatio Temporal ◽  
Blood Flow Velocities

The aim of the study was to better understand blood-flow changes in large arteries and microvessels during the first 15 minutes of reflow in a P7 rat model of arterial occlusion. Blood-flow changes were monitored by using ultrasound imaging with sequential Doppler recordings in internal carotid arteries (ICAs) and basilar trunk. Relative cerebral blood flow (rCBF) changes were obtained by using laser speckle Doppler monitoring. Tissue perfusion was measured with [14C]-iodoantipyrine autoradiography. Cerebral energy metabolism was evaluated by mitochondrial oxygen consumption. Gradual increase in mean blood-flow velocities illustrated a gradual perfusion during early reflow in both ICAs. On ischemia, the middle cerebral artery (MCA) territory presented a residual perfusion, whereas the caudal territory remained normally perfused. On reflow, speckle images showed a caudorostral propagation of reperfusion through anastomotic connections, and a reduced perfusion in the MCA territory. Autoradiography highlighted the caudorostral gradient, and persistent perfusion in ventral and medial regions. These blood-flow changes were accompanied by mitochondrial respiration impairment in the ipsilateral cortex. Collectively, these data indicate the presence of a primary collateral pathway through the circle of Willis, providing an immediate diversion of blood flow toward ischemic regions, and secondary efficient cortical anastomoses in the immature rat brain.

scholarly journals Monitoring of rhythms in laser speckle data

2014 ◽  
Vol 07 (03) ◽  
pp. 1450015 ◽  
Author(s):  
D. E. Postnov ◽  
A. Y. Neganova ◽  
D. D. Postnov ◽  
A. R. Brazhe
Keyword(s):  
Blood Flow ◽  
Graphics Processing Units ◽  
Surrogate Data ◽  
Laser Speckle ◽  
Tubuloglomerular Feedback ◽  
Additional Information ◽  
3D Data ◽  
Kidney Blood Flow ◽  
Rhythm Analysis ◽  
Spatio Temporal

While the laser speckle imaging (LSI) is a powerful tool for multiple biomedical applications, such as monitoring of the blood flow, in many cases it can provide additional information when combined with spatio-temporal rhythm analysis. We demonstrate the application of Graphics Processing Units (GPU)-based rhythm analysis for the post processing of LSI data, discuss the relevant structure of GPU-based computations, test the proposed technique on surrogate 3D data, and apply this approach to kidney blood flow autoregulation. Experiments with surrogate data demonstrate the ability of the method to extract information about oscillation patterns from noisy data, as well as to detect the moving source of the rhythm. The analysis of kidney data allow us to detect and to localize the dynamics arising from autoregulation processes at the level of individual nephrons (tubuloglomerular feedback (TGF) rhythm), as well as to distinguish between the TGF-active and the TGF-silent zones.

scholarly journals Comparison of Indocyanine Green Angiography and Laser Speckle Contrast Imaging for the Assessment of Vasculature Perfusion

Neurosurgery ◽  
2012 ◽  
Vol 71 (5) ◽  
pp. 1023-1031 ◽  
Author(s):  
Erica L. Towle ◽  
Lisa M. Richards ◽  
S. M. Shams Kazmi ◽  
Douglas J. Fox ◽  
Andrew K. Dunn
Keyword(s):  
Blood Flow ◽  
Indocyanine Green ◽  
Single Point ◽  
Tissue Perfusion ◽  
Laser Speckle ◽  
Optical Methods ◽  
Contrast Imaging ◽  
Laser Speckle Contrast Imaging ◽  
Speckle Contrast ◽  
Excellent Method

Abstract BACKGROUND: Assessment of the vasculature is critical for overall success in cranial vascular neurological surgery procedures. Although several methods of monitoring cortical perfusion intraoperatively are available, not all are appropriate or convenient in a surgical environment. Recently, 2 optical methods of care have emerged that are able to obtain high spatial resolution images with easily implemented instrumentation: indocyanine green (ICG) angiography and laser speckle contrast imaging (LSCI). OBJECTIVE: To evaluate the usefulness of ICG and LSCI in measuring vessel perfusion. METHODS: An experimental setup was developed that simultaneously collects measurements of ICG fluorescence and LSCI in a rodent model. A 785-nm laser diode was used for both excitation of the ICG dye and the LSCI illumination. A photothrombotic clot model was used to occlude specific vessels within the field of view to enable comparison of the 2 methods for monitoring vessel perfusion. RESULTS: The induced blood flow change demonstrated that ICG is an excellent method for visualizing the volume and type of vessel at a single point in time; however, it is not always an accurate representation of blood flow. In contrast, LSCI provides a continuous and accurate measurement of blood flow changes without the need of an external contrast agent. CONCLUSION: These 2 methods should be used together to obtain a complete understanding of tissue perfusion.

scholarly journals Dynamic Laser Speckle Imaging

2019 ◽  
Author(s):  
Dmitry D. Postnov ◽  
Jianbo Tang ◽  
Sefik Evren Erdener ◽  
Kıvılcım Kılıç ◽  
David A. Boas
Keyword(s):  
Blood Flow ◽  
Correlation Function ◽  
Light Scattering ◽  
Multiple Scattering ◽  
Laser Speckle ◽  
Laser Speckle Imaging ◽  
Speckle Imaging ◽  
Auto Correlation ◽  
Auto Correlation Function ◽  
Flow Changes

ABSTRACTUtilizing a high-speed camera and recording back-scattered laser light at more than 20,000 frames per second, we introduce the first wide-field dynamic laser speckle imaging (DLSI) in which we are able to quantify the laser speckleintensity temporal auto-correlation function g2(τ) for every pixel individually to obtain a quantitative image of the dynamics of the light scattering particles in the sample. The ability to directly and quantitatively measure the intensity auto-correlation function allows us to solve the problem of how to quantitatively interpret data measured by laser speckle contrast imaging (LSCI), multi-exposure laser speckle imaging (MESI) and laser Doppler flowmetry (LDF). The intensity auto-correlation function is related to the field temporal auto-correlation function g1(τ), which has been quantitatively related to the dynamics of the light scattering particles including flowing red blood cells. The form of g1(τ) depends on the amount of light scattering (i.e. single or multiple scattering) and the type of particle motion (i.e. ordered or unordered). Although these forms of the field correlation functions have been established for over 30 years, there is no agreement nor experimental support on what scattering and motion regimes are relevant for the varied biomedical applications. We thus apply DLSI to image cerebral blood flow in mouse through a cranial window and show that the generally accepted form of g1(τ), is applicable only to visible surface vessels of a specific size (20 – 200μm). We demonstrate that for flow in smaller vessels and in parenchymal regions that the proper g1(τ) form corresponds with multiple scattering light and unordered motion which was never considered to be relevant for these techniques. We show that the wrong assumption for the field auto-correlation model results in a severe underestimation of flow changes when measuring blood flow changes during ischemic stroke. Finally, we describe how DLSI can be integrated with other laser speckle methods to guide model selection, or how it can be used by itself as a quantitative blood flow imaging technique.

scholarly journals Monitoring of cerebral blood flow during hypoxia-ischemia and resuscitation in the neonatal rat using laser speckle imaging

2016 ◽  
Vol 4 (7) ◽  
pp. e12749 ◽  
Author(s):  
Thomas Wood ◽  
Elisa Smit ◽  
Elke Maes ◽  
Damjan Osredkar ◽  
Mari Falck ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Laser Speckle ◽  
Neonatal Rat ◽  
Laser Speckle Imaging ◽  
Speckle Imaging ◽  
Hypoxia Ischemia

Blood-borne vasodilating agent from ischemic tissues

1960 ◽  
Vol 15 (6) ◽  
pp. 1041-1045 ◽  
Author(s):  
B. R. Freeburg ◽  
Chester Hyman
Keyword(s):  
Blood Flow ◽  
Forearm Blood Flow ◽  
Peripheral Resistance ◽  
Arterial Occlusion ◽  
Flow Changes ◽  
Sustained Increase

Plethysmographic measurements of forearm blood flow show a drop to minimal values immediately after release of arterial occlusion of a leg; this is soon followed by a somewhat greater and more sustained increase to values above the control. Prepacking the leg with blood before arterial occlusion, or exercise before occlusion, or a combination of these procedures does not significantly alter the response. Calculated peripheral resistance in the forearm follows the pattern implied by the blood flow changes. It is suggested that the initial vasoconstriction is a reflex whereas the later vasodilatation is due to a stable, circulating agent from the previously ischemic leg. Submitted on April 29, 1960

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