Laser speckle contrast imaging: Multifractal analysis of data recorded in healthy subjects

Humeau-Heurtier, Anne; Durand, Sylvain; Henrion, Didier; Ábrahám, Pierre

doi:10.1118/1.4748506

Cited by 9 publications

(16 citation statements)

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“…This means that, when the ROI size increases and when LSCI pixel values are averaged in ROI and followed with time, the patterns of the resulting time series approach the patterns of LDF signals. These results are in accordance with other studies where it has been reported, via other signal processing methods, that LSCI pattern becomes close to the one of LDF data for ROI large enough [47], [49], [50]. However, from our results, this is not the case when recordings are performed during a vascular occlusion (see Fig.…”

Section: Discussionsupporting

confidence: 90%

“…The average value for the distance obtained for all the subjects is then computed, for each value of ( varies between 4 and 12) and for each recording procedure (rest and biological zero). 2) Around each pixel chosen in 1), square ROI of size 3 3 pixels (1.44 mm ), 9 9 pixels (12.96 mm ), 15 [49], [50]. For each ROI, the mean of the pixel values (in ) inside the ROI is computed and followed on each image of the sequence to obtain a time-evolution signal.…”

Section: Linguistic Analysis and Implementationmentioning

confidence: 99%

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Linguistic Analysis of Laser Speckle Contrast Images Recorded at Rest and During Biological Zero: Comparison With Laser Doppler Flowmetry Data

Humeau-Heurtier

Ábrahám

Mahé

2013

IEEE Trans. Med. Imaging

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Laser speckle contrast imaging (LSCI) is a newly commercialized imaging modality to monitor microvascular blood flow. Contrary to the well-known laser Doppler flowmetry (LDF), LSCI has the advantage of giving a full-field image of surface blood flow using simple instrumentation. However, laser speckle contrast images are not fully understood yet and their link with LDF signals still has to be studied. To quantify the similarity between LSCI and LDF symbolic sequences, we propose to use, for the first time, the index adapted from linguistic analysis and information theory proposed by Yang For this purpose, LSCI and LDF data were recorded simultaneously on the forearm of healthy subjects, at rest and during a vascular occlusion (biological zero). We show that there are different dynamical patterns for LSCI and LDF data, and the distances between these patterns differ through the space scales explored. Moreover, our results suggest that these different dynamical patterns could be linked to blood flow. The quantitative metric used herein therefore provides new information on LSCI and brings knowledge on links between LSCI and LDF.

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Section: Discussionsupporting

confidence: 90%

Section: Linguistic Analysis and Implementationmentioning

confidence: 99%

Linguistic Analysis of Laser Speckle Contrast Images Recorded at Rest and During Biological Zero: Comparison With Laser Doppler Flowmetry Data

Humeau-Heurtier

Ábrahám

Mahé

2013

IEEE Trans. Med. Imaging

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“…This means that, for scale factors larger than three, LDF signals complexity becomes closer to the ones of LSCI time series with the largest ROI size. These results are in accordance with previous works where it has been reported that: (i) there are different dynamical patterns for LSCI and LDF data [26]; (ii) when the ROI size increases in LSCI data and when LSCI pixel values are averaged in ROI and followed with time, the patterns of the resulting time series approach the patterns of LDF signals [26,31,32,38]. Several studies have been carried on compression entropy [34,37,[39][40][41][42][43][44][45][46].…”

Section: Discussionsupporting

confidence: 80%

“…The global decreasing trend observed for LSCI time series computed from the smallest ROI sizes are in accordance with other works, where it has been reported that LSCI single pixels (or small ROI sizes) in time have statistical properties similar to those of white noise [31,32]. It has also been reported that, for larger ROI sizes on LSCI data, the signal-to-noise ratio increases and the behavior asymptotically approaches the one of LDF [31,32]. Our findings are therefore consistent with these previous results.…”

Section: Discussionsupporting

confidence: 76%

“…This pixel was followed with time to obtain a time series of 1,600 samples. Moreover, around each pixel chosen above, square regions of interest (ROI) of a size of 3 × 3 pixels 2 (1.44 mm 2 ) and 15 × 15 pixels 2 (36 mm 2 ) were determined [26,31,32]. For each ROI, the mean of the pixel values (in APU LSCI ) inside the ROI was computed and followed on each image of the sequence to obtain a time-evolution signal (see Figure 3).…”

Section: Measurement Proceduresmentioning

confidence: 99%

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Multiscale Compression Entropy of Microvascular Blood FlowSignals: Comparison of Results from Laser Speckle Contrastand Laser Doppler Flowmetry Data in Healthy Subjects

Humeau-Heurtier

Baumert

Ábrahám

2014

Entropy

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Microvascular perfusion is commonly used to study the peripheral cardiovascular system. Microvascular blood flow can be continuously and non-invasively monitored with laser speckle contrast imaging (LSCI) or with laser Doppler flowmetry (LDF). These two optical-based techniques give perfusion values in arbitrary units. Our goal is to better understand the perfusion time series given by each technique. For this purpose, we propose a nonlinear complexity analysis of LSCI and LDF time series recorded simultaneously in nine healthy subjects. This is performed through the computation of their multiscale compression entropy. The results obtained with LSCI time series computed from different regions of interest (ROI) sizes are examined. Our findings show that, for LSCI and LDF time series, compression entropy values are less than one for all of the scales analyzed. This suggests that, for all scales, there are repetitive structures within the data fluctuations. Moreover, at the largest scales studied, LDF signals seem to have structures that are different from those Entropy 2014, 16 5778 of Gaussian white noise. By opposition, this is not observed for LSCI time series computed from small ROI sizes.

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Assessment of cerebral hemodynamics during neurosurgical procedures using laser speckle image analysis

Venugopal

Sujatha

Bach

et al. 2019

Journal of Biophotonics

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Aneurysmal subarachnoid hemorrhage (aSAH) is a severe medical condition associated with a significant cause of mortality throughout the world. Cisterna magna injection model is accepted widely to mimic clinical aSAH and is performed on small animal models to study aSAH during neurosurgery. Coherent light scattered from the surface of the rat brain is used to infer information about the variations in blood flow during this condition. We obtained speckle images from the exposed cortex during the entire experiment using an external tissue imaging system. Contrast and fractal analyses are carried out for the recorded speckle pattern time series. Correlation analysis based on Hurst exponent for these images is found to be a more sensitive tool in studying aSAH as compared to routinely used laser speckle contrast analysis for assessing the changes in blood flow velocity. Additionally, our studies provide improved blood flow detection sensitivity with image Hurst exponent in combination with computed fractal dimension, during an event of aSAH.

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Laser speckle contrast imaging: Multifractal analysis of data recorded in healthy subjects

Abstract: Single pixels from laser speckle contrast images may not possess the same multifractal properties as LDF signals. These findings could now be compared with the ones obtained with other ranges of scales and with data recorded from pathological subjects.

Cited by 9 publications

References 50 publications

Linguistic Analysis of Laser Speckle Contrast Images Recorded at Rest and During Biological Zero: Comparison With Laser Doppler Flowmetry Data

Linguistic Analysis of Laser Speckle Contrast Images Recorded at Rest and During Biological Zero: Comparison With Laser Doppler Flowmetry Data

Multiscale Compression Entropy of Microvascular Blood FlowSignals: Comparison of Results from Laser Speckle Contrastand Laser Doppler Flowmetry Data in Healthy Subjects

Assessment of cerebral hemodynamics during neurosurgical procedures using laser speckle image analysis

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