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TitleSpatial and temporal effects in laser speckle perfusion measurement
Publication TypeConference Paper
Year of Publication2009
AuthorsThompson, O.B., and Andrews M.K.
Conference NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Date Published2009
KeywordsBlood, Blood flow, Dermal perfusion, Dynamics, Hemodynamics, Image resolution, Laser speckle, Lasers, Measurements, Movement artefacts, Physiological models, Pulse measurement, Pulsed laser applications, Speckle
AbstractLaser speckle contrast techniques have been increasingly applied to dermal perfusion measurements over the past few years. The interpretation of laser speckle contrast and its conversion to a physiologically-defined perfusion parameter related to that found from Doppler measurements is becoming clearer. Speckle contrast-based techniques provide both quantified perfusion images and a time-series record of perfusion. We use the image resolution available in speckle measurements to investigate spatial resolution which can be expected in tissue; in particular to reconcile speckle measurements with the large point-to-point variations reported from fibre Doppler probes. In vitro models show the extent of spatial blurring likely to be encountered in speckle measurements at different depths. Perfusion responses related to vascular challenges could have medical relevance. We find a small pulse-related signal in dermal speckle data. By identifying pulses in a temporal record using a matched filter, we find statistical average pulse shapes for several different subjects, allowing comparison of pulsatile flow profiles between them. The profiles measured by this technique are repeatable on the same subject, and vary between subjects. At some body sites, notably near arterioles, the response obviously relates to gross tissue motion, but at others the signature is of dermal origin. It is not yet clear whether it relates to actual capillary flow variation or distortion of the scattering tissue in response to changes in the driving pressure. © 2009 SPIE.

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