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Laser speckle contrast imaging

Recently, there has been great interest in using laser speckle contrast imaging (LSCI) as a tool for imaging flow in preclinical research and clinical applications. LSCI utilizes intrinsic tissue contrast from dynamic light scattering and provides a relatively simple technique for visualizing detailed spatiotemporal dynamics of blood flow changes in real-time. Laser speckle is a random interference pattern produced when coherent light scatters from a random medium and can be imaged onto a detector. Motion from scattering particles, such as red blood cells in the vasculature, leads to spatial and temporal variations in the speckle pattern. Speckle contrast analysis quantifies the local spatial variance, or blurring, of the speckle pattern that results from blood flow. Areas with greater motion have more rapid intensity fluctuations and therefore have more blurring of the speckles during the camera exposure time. LSCI can be used to quantify relative changes in blood flow, and has been studied both in animal models and in the clinic.

In our lab, we focus on functional brain imaging and use LSCI to image cerebral blood flow dynamics. Cerebral blood flow (CBF) is an important parameter in the brain, and can be used to study neurological events, including stroke, cortical spreading depression, and functional activation. In animal models, we can use LSCI as a tool to better understand the neurophysiological mechanisms behind each of these events, which can impact future development of therapeutics. In the clinic, LSCI can be used as a monitoring tool during neurosurgery, alerting surgeons of a reduction in cerebral blood flow in a timely manner to reduce the risk of post-operative deficits.

Recent research projects:

  • Development of a low-cost LSCI system that can image microcirculatory blood flow
  • Assessment of LSCI as an intraoperative blood flow monitoring tool during brain tumor resection procedures

Publications Related to this Research Area

Low-cost laser speckle contrast imaging of blood flow using a webcam

L. M. Richards, S. M. Shams Kazmi, J. L. Davis, K. E. Olin, A. K. Dunn,

Biomedical Optics Express

Comparison of indocyanine green angiography and laser speckle contrast imaging for the assessment of vasculature perfusion.

E. L. Towle, L. M. Richards, S. Kazmi, D. J. Fox, A. K. Dunn,

Neurosurgery

Laser speckle contrast imaging of cerebral blood flow in humans during neurosurgery: a pilot clinical study

A. B. Parthasarathy, E. L. Weber, L. M. Richards, D. J. Fox, A. K. Dunn,

Journal of Biomedical Optics

Relative blood flow overlay with a webcam

Acquired using a webcam, inexpensive aspheric lenses, and a laser pointer, this image shows baseline speckle contrast images overlaid with the reduction in blood flow after a stroke in a mouse. The scale of the color overlay displays all flows <35% of the baseline value.