Laser speckle contrast imaging in biomedical optics

Abstract

Abstract. First introduced in the 1980s, laser speckle contrast imaging is a powerful tool for full-field imaging of blood flow. Recently laser speckle contrast imaging has gained increased attention, in part due to its rapid adoption for blood flow studies in the brain. We review the underlying physics of speckle contrast imaging and discuss recent developments to improve the quantitative accuracy of blood flow measures. We also review applications of laser speckle contrast imaging in neuroscience, dermatology and ophthalmology.

Chronic Imaging of Cortical Blood Flow using Multi-Exposure Speckle Imaging

“…These are the camera exposure durations most commonly used for in vivo studies 30 and have been shown to have optimal flow sensitivity in rodents. 31 Laser Speckle Contrast Imaging correlation times were calculated from the speckle contrast values using the expression 32 :…”

Transdermal iontophoresis as an in-vivo technique for studying microvascular physiology

“…The technique in theory combines the advantages of single-point LDF and scanning LDPI techniques, as it provides instantaneous recording of the perfusion in an area of tissue. Laser Speckle Contrast Imaging is based on the analysis of speckle contrast and, like LDF and LDPI, provides a perfusion measure that is proportional to the concentration and the average velocity of red blood cells (Boas and Dunn, 2010;Briers, 2001;O'Doherty et al, 2009). …”

‘Go with the flow ’: A review of methods and advancements in blood flow imaging

“…The amount of decorrelation depends on the speed and volume of the scatterers in the tissue. To quantify the blurring of the speckles, the speckle contrast is computed as the ratio [110,111]:…”

“…The time-varying component of speckle may be quantified by comparisons of like pixel intensities recorded in successive scans of the subject, thus forming 2D maps of flow across the region of interest. A successful approach was developed using laser speckle contrast analysis (LASCA), which assumes that (considering a Lorenztian flow profile) the speckle contrast could be related to correlation time t C (and hence RBC V ) [110,112]:…”

“…Although accurate absolute measurements RBC V cannot be calculated, perfusion changes can be successively monitored and tracked. Laser speckle imaging has been demonstrated on the rodent skin fold model [119,120], assessed the vasodilation responses of intestinal tissues [121], analysed retinal blood flow and cerebral perfusion [122][123][124][125], and stroke [110].…”