Tissue perfusion measurements: multiple-exposure laser speckle analysis generates laser Doppler–like spectra

Thompson, Oliver; Andrews, M. K.

doi:10.1117/1.3400721

Cited by 70 publications

(67 citation statements)

References 25 publications

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“…For fully Doppler shifted speckle patterns, Thompson and Andrews 16 have shown that the Doppler power spectrum can be calculated using the second derivative of the squared contrast with respect to the exposure time T. Following their work, the second derivative of a partially Doppler shifted speckle pattern can be described by …”

Section: From Contrast To Doppler Power Spectrummentioning

confidence: 99%

“…14,15 Based on these relationships, Thompson and Andrews have demonstrated that the Doppler power spectrum can in fact be deduced from the speckle contrast if the contrast is resolved as a function of exposure time. 16 In most LASCA studies, however, only a single exposure time has been used. As a single exposure LASCA image contains information from all Doppler frequencies, it will produce perfusion estimates that to some extent are sensitive to both the speed and the amount of moving red blood cells.…”

mentioning

confidence: 99%

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On the equivalence and differences between laser Doppler flowmetry and laser speckle contrast analysis

Fredriksson

Larsson

2016

J. Biomed. Opt

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, "On the equivalence and differences between laser Doppler flowmetry and laser speckle contrast analysis," J. Abstract. Laser Doppler flowmetry (LDF) and laser speckle contrast analysis (LASCA) both utilize the spatiotemporal properties of laser speckle patterns to assess microcirculatory blood flow in tissue. Although the techniques analyze the speckle pattern differently, there is a close relationship between them. We present a theoretical overview describing how the LDF power spectrum and the LASCA contrast can be calculated from each other, and how both these can be calculated from an optical Doppler spectrum containing various degrees of Doppler shifted light. The theoretical relationships are further demonstrated using time-resolved speckle simulations. A wide range of Monte Carlo simulated tissue models is then used to show how perfusion estimates for LDF and LASCA are affected by changes in blood concentration and speed distribution, as well as by geometrical and optical properties. We conclude that perfusion estimates from conventional single exposure time LASCA are in general more sensitive to changes in optical and geometrical properties and are less accurate in the prediction of real perfusion changes, especially speed changes. Since there is a theoretical one-to-one relationship between Doppler power spectrum and contrast, one can conclude that those drawbacks with the LASCA technique can be overcome using a multiple exposure time setup.

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Section: From Contrast To Doppler Power Spectrummentioning

confidence: 99%

mentioning

confidence: 99%

On the equivalence and differences between laser Doppler flowmetry and laser speckle contrast analysis

Fredriksson

Larsson

2016

J. Biomed. Opt

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“…Thompson and Andrews 62 have suggested that this can effectively be done by using multiple exposures. They showed that between 10 and 15 exposures, with each successive exposure being double the previous one, are sufficient to produce data on a par with Doppler techniques.…”

Section: Velocity Distributionmentioning

confidence: 99%

Laser speckle contrast imaging: theoretical and practical limitations

Briers¹,

Duncan²,

Hirst³

et al. 2013

J. Biomed. Opt

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465

324

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Abstract. When laser light illuminates a diffuse object, it produces a random interference effect known as a speckle pattern. If there is movement in the object, the speckles fluctuate in intensity. These fluctuations can provide information about the movement. A simple way of accessing this information is to image the speckle pattern with an exposure time longer than the shortest speckle fluctuation time scale-the fluctuations cause a blurring of the speckle, leading to a reduction in the local speckle contrast. Thus, velocity distributions are coded as speckle contrast variations. The same information can be obtained by using the Doppler effect, but producing a two-dimensional Doppler map requires either scanning of the laser beam or imaging with a high-speed camera: laser speckle contrast imaging (LSCI) avoids the need to scan and can be performed with a normal CCD-or CMOS-camera. LSCI is used primarily to map flow systems, especially blood flow. The development of LSCI is reviewed and its limitations and problems are investigated.

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“…The capability of LSR to assess blood coagulation status in real-time as demonstrated in this study will open new opportunities for assessing a patient's blood coagulation status at the point of care. The analysis of laser speckle patterns has been investigated for a number of biomedical applications such as the measurement of blood flow and tissue perfusion [33,34] and for skin surface roughness assessment [35]. LSR is distinct in that as it measures the viscoelastic properties of blood from time-resolved laser speckle intensity fluctuations to determine blood coagulation status in patients.…”

Section: Discussionmentioning

confidence: 99%

Assessing blood coagulation status with laser speckle rheology

Tripathi

Hajjarian

Cott

et al. 2014

Biomed. Opt. Express

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Abstract:We have developed and investigated a novel optical approach, Laser Speckle Rheology (LSR), to evaluate a patient's coagulation status by measuring the viscoelastic properties of blood during coagulation. In LSR, a blood sample is illuminated with laser light and temporal speckle intensity fluctuations are measured using a high-speed CMOS camera. During blood coagulation, changes in the viscoelastic properties of the clot restrict Brownian displacements of light scattering centers within the sample, altering the rate of speckle intensity fluctuations. As a result, blood coagulation status can be measured by relating the time scale of speckle intensity fluctuations with clinically relevant coagulation metrics including clotting time and fibrinogen content. Our results report a close correlation between coagulation metrics measured using LSR and conventional coagulation results of activated partial thromboplastin time, prothrombin time and functional fibrinogen levels, creating the unique opportunity to evaluate a patient's coagulation status in real-time at the point of care. (2013). 11. M. Kaibara, "Rheology of blood coagulation," Biorheology 33(2), 101-117 (1996). 12. C. E. Dempfle, T. Kälsch, E. Elmas, N. Suvajac, T. Lücke, E. Münch, and M. Borggrefe, "Impact of fibrinogen concentration in severely ill patients on mechanical properties of whole blood clots," Blood Coagul.

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Tissue perfusion measurements: multiple-exposure laser speckle analysis generates laser Doppler–like spectra

Cited by 70 publications

References 25 publications

On the equivalence and differences between laser Doppler flowmetry and laser speckle contrast analysis

On the equivalence and differences between laser Doppler flowmetry and laser speckle contrast analysis

Laser speckle contrast imaging: theoretical and practical limitations

Assessing blood coagulation status with laser speckle rheology

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