Effects of speckle/pixel size ratio on temporal and spatial speckle-contrast analysis of dynamic scattering systems: Implications for measurements of blood-flow dynamics

Ramírez-San-Juan, J. C.; Méndez-Aguilar, Emilia M.; Salazar-Hermenegildo, N.; Fuentes-Garcia, A.; Ramos-Garcı́a, R.; Choi, Bernard

doi:10.1364/boe.4.001883

Cited by 44 publications

(23 citation statements)

References 17 publications

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“…1(b), we can observe the validity of β correction in correcting μ K and μ T/τ , even at a speckle size of 0.125 pixel. As expected, at each speckle size, the calibrated μ T/τ shows a linear relation with m. The sensitivity of LSCI in detecting relative change in flow speed keeps basically constant with speckle size, which is in agreement with [30]. Figures 1(e) and 1(f) show the dependences of σ K /μ K and σ T/τ /μ T/τ on m and speckle size.…”

Section: Analysis Of Simulated Datasupporting

confidence: 85%

Correcting speckle contrast at small speckle size to enhance signal to noise ratio for laser speckle contrast imaging

Qiu¹,

Li²,

Huang³

et al. 2013

Opt. Express

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In laser speckle contrast imaging, it was usually suggested that speckle size should exceed two camera pixels to eliminate the spatial averaging effect. In this work, we show the benefit of enhancing signal to noise ratio by correcting the speckle contrast at small speckle size. Through simulations and experiments, we demonstrated that local speckle contrast, even at speckle size much smaller than one pixel size, can be corrected through dividing the original speckle contrast by the static speckle contrast. Moreover, we show a 50% higher signal to noise ratio of the speckle contrast image at speckle size below 0.5 pixel size than that at speckle size of two pixels. These results indicate the possibility of selecting a relatively large aperture to simultaneously ensure sufficient light intensity and high accuracy and signal to noise ratio, making the laser speckle contrast imaging more flexible.

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Section: Analysis Of Simulated Datasupporting

confidence: 85%

Correcting speckle contrast at small speckle size to enhance signal to noise ratio for laser speckle contrast imaging

Qiu¹,

Li²,

Huang³

et al. 2013

Opt. Express

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show abstract

“…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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“…12 This improved accuracy appears to be from the reduction in sensitivity of temporal analysis to the presence of static optical scatterers. We discovered that the temporal algorithm is more accurate than the spatial algorithm at assessing the relative change in flow speed.…”

Section: Introductionmentioning

confidence: 99%

Spatial versus temporal laser speckle contrast analyses in the presence of static optical scatterers

et al. 2014

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Previously published data demonstrate that the temporal processing algorithm for laser speckle contrast imaging (LSCI) can improve the visibility of deep blood vessels and is less susceptible to static speckle artifacts when compared with the spatial algorithm. To the best of our knowledge, the extent to which the temporal algorithm can accurately predict the speckle contrast associated with flow in deep blood vessels has not been quantified. Here, we employed two phantom systems and imaging setups (epi-illumination and transillumination) to study the contrast predicted by the spatial and temporal algorithms in subsurface capillary tubes as a function of the camera exposure time and the actual flow speed. Our data with both imaging setups suggest that the contrast predicted by the temporal algorithm, and therefore the relative flow speed, is nearly independent of the degree of static optical scattering that contributes to the overall measured speckle pattern. Collectively, these results strongly suggest the potential of temporal LSCI at a single-exposure time to assess accurately the changes in blood flow even in the presence of substantial static optical scattering.

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Effects of speckle/pixel size ratio on temporal and spatial speckle-contrast analysis of dynamic scattering systems: Implications for measurements of blood-flow dynamics

Cited by 44 publications

References 17 publications

Correcting speckle contrast at small speckle size to enhance signal to noise ratio for laser speckle contrast imaging

Correcting speckle contrast at small speckle size to enhance signal to noise ratio for laser speckle contrast imaging

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

Spatial versus temporal laser speckle contrast analyses in the presence of static optical scatterers

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