Quantitative laser speckle flowmetry of the in vivo microcirculation using sidestream dark field microscopy

Nadort, Annemarie; Woolthuis, Rutger G.; Leeuwen, Ton G. van; Faber, Dirk J.

doi:10.1364/boe.4.002347

Cited by 31 publications

(64 citation statements)

References 33 publications

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“…With this hypothesis, we assume that 1) a single voxel at a functional blood vessel has a time scale of random fluctuations of OCT speckle owing to random motion of RBCs passing through this voxel (here, most of constituents of blood are assumed to be red blood cells), and 2) the OCT speckle dynamics at single voxel can be quantified by using the temporal statistics of the speckle pattern. For the temporal assessment of speckle dynamics, usually, the characteristic decorrelation time τ c is derived through the Siegert relation: g 2 (τ) = 1 + β M |g 1 (τ)| 2 [22], where β M is a measurement-geometry specific constant, g 1 (τ) and g 2 (τ) are the autocorrelation functions of scattered electric field and intensity, respectively. However, because of difficulty in direct derivation of τ c from the g 1 (τ), most of LSCI investigations have been focused on the spatial assessment of speckle dynamics for derivation of τ c .…”

Section: Basic Conceptmentioning

confidence: 99%

“…For this, we utilize the speckle contrast analytical models that have been already well-established in the many LSCI literatures [21,22]. Table 1 shows the modified Siegert relation based speckle visibility expressions for different scattering regimes and different velocity distributions.…”

Section: Derivation Of Temporal Decorrelation Timementioning

confidence: 99%

“…(3), a decorrelation time τ c can be extracted with the temporal speckle contrast K t obtained from OCT signal fluctuations and the known time interval t. As stated, τ c should have an inverse linear relationship with flow velocity V; V = ατ c −1 , where α is a weighting factor depending on a combination of scatter properties and imaging geometry [22]. In Sec.…”

Section: Derivation Of Temporal Decorrelation Timementioning

confidence: 99%

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Cerebral capillary velocimetry based on temporal OCT speckle contrast

Choi

Wan

et al. 2016

Biomed. Opt. Express

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Abstract:We propose a new optical coherence tomography (OCT) based method to measure red blood cell (RBC) velocities of single capillaries in the cortex of rodent brain. This OCT capillary velocimetry exploits quantitative laser speckle contrast analysis to estimate speckle decorrelation rate from the measured temporal OCT speckle signals, which is related to microcirculatory flow velocity. We hypothesize that OCT signal due to sub-surface capillary flow can be treated as the speckle signal in the single scattering regime and thus its time scale of speckle fluctuations can be subjected to single scattering laser speckle contrast analysis to derive characteristic decorrelation time. To validate this hypothesis, OCT measurements are conducted on a single capillary flow phantom operating at preset velocities, in which M-mode B-frames are acquired using a high-speed OCT system. Analysis is then performed on the time-varying OCT signals extracted at the capillary flow, exhibiting a typical inverse relationship between the estimated decorrelation time and absolute RBC velocity, which is then used to deduce the capillary velocities. We apply the method to in vivo measurements of mouse brain, demonstrating that the proposed approach provides additional useful information in the quantitative assessment of capillary hemodynamics, complementary to that of OCT angiography.

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Section: Basic Conceptmentioning

confidence: 99%

Section: Derivation Of Temporal Decorrelation Timementioning

confidence: 99%

Section: Derivation Of Temporal Decorrelation Timementioning

confidence: 99%

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Cerebral capillary velocimetry based on temporal OCT speckle contrast

Choi

Wan

et al. 2016

Biomed. Opt. Express

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“…Particularly, the use of multiple camera exposures spanning nearly three decades of duration has enabled better sampling and mapping of the flow distributions in the specimen. Therefore, MESI is quickly being recognized as a substantial and necessary step in the progression of laser speckle flowmetry [22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

Kazmi

Balial

Dunn

2014

Biomed. Opt. Express

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Improved Laser Speckle Contrast Imaging (LSCI) blood flow analyses that incorporate inverse models of the underlying laser-tissue interaction have been used to develop more quantitative implementations of speckle flowmetry such as Multi-Exposure Speckle Imaging (MESI). In this paper, we determine the optimal camera exposure durations required for obtaining flow information with comparable accuracy with the prevailing MESI implementation utilized in recent in vivo rodent studies. A looping leave-one-out (LOO) algorithm was used to identify exposure subsets which were analyzed for accuracy against flows obtained from analysis with the original full exposure set over 9 animals comprising n = 314 regional flow measurements. From the 15 original exposures, 6 exposures were found using the LOO process to provide comparable accuracy, defined as being no more than 10% deviant, with the original flow measurements. The optimal subset of exposures provides a basis set of camera durations for speckle flowmetry studies of the microcirculation and confers a twofold faster acquisition rate and a 28% reduction in processing time without sacrificing accuracy. Additionally, the optimization process can be used to identify further reductions in the exposure subsets for tailoring imaging over less expansive flow distributions to enable even faster imaging.

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“…The increased depth of light penetration into the tissue using SDF allows the deeper arterioles to be clearly observed in the sublingual area where it is usually placed. The imaging output on a monitor portrays RBCs flowing as a dark moving globules against a white/grayish background [8]. Imaging optimization correcting for motion-induced hemoglobin blurring (i.e., flowing RBCs) has been resolved by synchronizing the LED light pulse illumination with the CCD camera frame rate, resulting in intravital stroboscopy using short illumination intervals (13 ms).…”

Section: A Principle Of Sdf Imagingmentioning

confidence: 99%

Determining the Optimal Site for Imaging the Microcirculation in Neonates Using Sidestream Dark – Field Imaging

Sklia

Kyriacou

Petros

2016

XIV Mediterranean Conference on Medical and Biological Engineering and Computing 2016

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This is the accepted version of the paper.This version of the publication may differ from the final published version. Abstract-Sidestream dark field (SDF) spectral imaging has been used to take pictures of capillaries within the skin. The most common location to place the SDF is the mucosa area in the mouth. However, in neonates the sublingual area is not easily accessible, thus an optimal location on the skin should be found. This feasibility study aims to determine the optimal site, out of five body areas on the neonate from which to obtain image of capillary microcirculation. These preliminary results indicate that the chest wall can be considered as the optimal measurement location on the skin when using the SDF modality. Permanent

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Quantitative laser speckle flowmetry of the in vivo microcirculation using sidestream dark field microscopy

Cited by 31 publications

References 33 publications

Cerebral capillary velocimetry based on temporal OCT speckle contrast

Cerebral capillary velocimetry based on temporal OCT speckle contrast

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

Determining the Optimal Site for Imaging the Microcirculation in Neonates Using Sidestream Dark – Field Imaging

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