Velocity resolved laser Doppler blood flow measurements in skin

Dörschel, K.; Müller, G.

doi:10.1016/s0955-5986(96)00017-9

Cited by 16 publications

(13 citation statements)

References 12 publications

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“…The study protocol was approved by the University's Ethical Review Board. Changes of the DWS autocorrelation function upon stimulation were quantified by the decay time of the bundle-averaged field autocorrelation function g (1) b (τ),…”

Section: Methodsmentioning

confidence: 99%

“…The lower integration limit is τ 1 = 4 × 10 −7 s, and τ 2 is defined by g (1) b (τ 2 ) = 0.1. Our choice of the upper integration limit τ 2 aims at suppressing contributions from short photon paths which do not carry information on the cortex, and, secondly, at reducing the noise in the decay time b (τ), measured over the primary visual cortex, from one subject for baseline (blue circles) and visual stimulation periods (red squares).…”

Section: Methodsmentioning

confidence: 99%

“…Our choice of the upper integration limit τ 2 aims at suppressing contributions from short photon paths which do not carry information on the cortex, and, secondly, at reducing the noise in the decay time b (τ), measured over the primary visual cortex, from one subject for baseline (blue circles) and visual stimulation periods (red squares). Bottom: difference ∆g Figure 2 shows the bundle-averaged field autocorrelation function g (1) b (τ) from one subject, as a function of the lag time τ, measured with the long-distance receiver for baseline and stimulation periods. During the stimulation period, the decay of the autocorrelation function is faster, indicating that the dynamics in the visual cortex area probed by the DWS experiment is accelerated, such as by an increase in CBF.…”

Section: Methodsmentioning

confidence: 99%

“…Fluctuations of the speckle intensity I(r r r,t) at the position r r r yield information on microscopic motions of scatterers within the volume swept by the diffuse photon cloud. In contrast to laser Doppler velocimetry where the power spectrum of speckle fluctuations measured in near-backscattering geometry is dominated by skin blood flow [1], diffusing-wave spectroscopy (DWS [2,3]; also called diffuse correlation spectroscopy, DCS) measures the temporal intensity autocorrelation function g (2) (τ) = I(0)I(τ) / |I(0)| 2 at large source-receiver distances of up to several centimeters. The high sensitivity to even minute scatterer displacements has lead to several applications of DWS in the fields of tumor and skeletal muscle perfusion [4,5,6,7,8,9, 10].…”

Section: Introductionmentioning

confidence: 99%

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Activity of the human visual cortex measured non-invasively by diffusing-wave spectroscopy

Jaillon¹,

Li²,

Dietsche³

et al. 2007

Opt. Express

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Activity of the human visual cortex, elicited by steady-state flickering at 8 Hz, is non-invasively probed by multi-speckle diffusingwave spectroscopy (DWS). Parallel detection of the intensity fluctuations of statistically equivalent, but independent speckles allows to resolve stimulation-induced changes in the field autocorrelation of multiply scattered light of less than 2%. In a group of 9 healthy subjects we find a faster decay of the field autocorrelation function during the stimulation periods for data measured with a long-distance probe (30 mm source-receiver distance) at 2 positions over the occipital cortex (t-test: t(8) = −2.672, p = 0.028 < 0.05 for position 1, t(8) = −2.874, p = 0.021 < 0.05 for position 2). In contrast, no statistically significant change is seen when a short-distance probe (16 mm source-receiver distance) is used (t-test: t(8) = −2.043, p = 0.075 > 0.05 for position 1, t(8) = −2.146, p = 0.064 > 0.05 for position 2). The enhanced dynamics observed with DWS is positively correlated with the functional increase of blood volume in the visual cortex, while the heartbeat rate is not affected by stimulation. Our results indicate that the DWS signal from the visual cortex is governed by the regional cerebral blood flow velocity.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Activity of the human visual cortex measured non-invasively by diffusing-wave spectroscopy

Jaillon¹,

Li²,

Dietsche³

et al. 2007

Opt. Express

View full text Add to dashboard Cite

show abstract

“…), the angle between the velocity vector and the scattering wave vector (" ), and the number of Doppler shifts in the case of multiple scattering. Dörschel and Müller [18] tried to solve the problem of the angle " (angle 8 in their manuscript) with the assumption of an isotropically distributed angle between the velocity and the scattering vector and calculated a corrected frequency spectrum as if all vectors were parallel. The spectrum was corrected for various directions of velocity and reference vector by multiplication of the Doppler shift by the differential coefficient of the spectrum, which ultimately will lead to a velocity-resolved flow measurement.…”

Section: Recent Theoretical Developmentsmentioning

confidence: 99%