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.

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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.

Ongoing Projects:

  • Low-cost system that can image microcirculatory blood flow
  • Multiple Exposure Speckle Imaging (MESI) for quantitative blood flow imaging
  • Intraoperative blood flow monitoring tool during brain tumor resection procedures

Relevant Publications

Evaluating multi-exposure speckle imaging estimates of absolute autocorrelation times

S. M. S. Kazmi, R. K. Wu, and A. K. Dunn,

Optics Letters

(2015)

Flux or speed? Examining speckle contrast imaging of vascular flows

S. M. S. Kazmi, E. Faraji, M. A. Davis, Y. Huang, X. J. Zhang, and A. K. Dunn,

Biomedical Optics Express

(2015)

Expanding applications, accuracy, and interpretation of laser speckle contrast imaging of cerebral blood flow

S. M. S. Kazmi, L. M. Richards, C. J. Schrandt, M. A. Davis, and A. K. Dunn,

Journal of Cerebral Blood Flow & Metabolism

(2015)

Chronic monitoring of vascular progression after ischemic stroke using multiexposure speckle imaging and two-photon fluorescence microscopy.

C. J. Schrandt, S. M. S. Kazmi, T. A. Jones, and A. K. Dunn,

Journal of Cerebral Blood Flow & Metabolism

(2015)

Intraoperative laser speckle contrast imaging with retrospective motion correction for quantitative assessment of cerebral blood flow

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

Neurophotonics

(2014)

Imaging depth and multiple scattering in laser speckle contrast imaging

M. A. Davis, S. M. S. Kazmi, A. K. Dunn,

Journal of Biomedical Optics

(2014)

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

S. M. S. Kazmi, S. Balial, A. K. Dunn,

Biomedical Optics Express

(2014)

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

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

Biomedical Optics Express

(2013)

Laser speckle contrast imaging of blood flow in rat retinas using an endoscope

A. Ponticorvo, D. Cardenas, A. K. Dunn, D. Ts’o, and T. Q. Duong,

Journal of Biomedical Optics

(2013)

Chronic imaging of cortical blood flow using Multi-Exposure Speckle Imaging.

S. M. S. Kazmi, A. B. Parthasarthy, N. E. Song, T. A. Jones, and A. K. Dunn,

Journal of Cerebral Blood Flow & Metabolism

(2013)

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

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

Neurosurgery

(2012)

Laser speckle contrast imaging of cerebral blood flow

A. K. Dunn,

Annals of Biomedical Engineering

(2012)

Introduction: feature issue on In Vivo Microcirculation Imaging

A. K. Dunn, R. Leitgeb, R. K. Wang, and H. F. Zhang,

Biomedical Optics Express

(2011)

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, and A. K. Dunn,

Journal of Biomedical Optics

(2010)

How to build a Laser Speckle Contrast Imaging (LSCI) system to monitor blood flow.

A. Ponticorvo and A. K. Dunn,

Journal of Visualized Experiments

(2010)

Quantitative imaging of ischemic stroke through thinned skull in mice with Multi Exposure Speckle Imaging

A. B. Parthasarathy, S. M. S. Kazmi, and A. K. Dunn,

Biomedical Optics Express

(2010)

Spreading depolarizations cycle around and enlarge focal ischaemic brain lesions

H. Nakamura, A. J. Strong, C. Dohmen, O. W. Sakowitz, S. Vollmar, M. Sue, L. Kracht, P. Hashemi, R. Bhatia, T. Yoshimine, J. P. Dreier, A. K. Dunn, and R. Graf,

Brain

(2010)

Simultaneous imaging of oxygen tension and blood flow in animals using a digital micromirror device

A. Ponticorvo and A. K. Dunn,

Optics Express

(2010)

Laser speckle contrast imaging in biomedical optics

D. A. Boas and A. K. Dunn,

Journal of Biomedical Optics

(2010)

Perfusion in hamster skin treated with glycerol

R. T. Zaman, A. B. Parthasarathy, G. Vargas, B. Chen, A. K. Dunn, H. G. Rylander, and A. J. Welch,

Lasers in Surgery and Medicine

(2009)

Sensitivity of neural-hemodynamic coupling to alterations in cerebral blood flow during hypercapnia

T. J. Huppert, P. B. Jones, A. Devor, A. K. Dunn, I. C. Teng, A. M. Dale, and D. A. Boas,

Journal of Biomedical Optics

(2009)

Simultaneous multispectral reflectance imaging and laser speckle flowmetry of cerebral blood flow and oxygen metabolism in focal cerebral ischemia

P. B. Jones, H. K. Shin, D. A. Boas, B. T. Hyman, M. A. Moskowitz, C. Ayata, and A. K. Dunn,

Journal of Biomedical Optics

(2008)

Robust flow measurement with multi-exposure speckle imaging

A. B. Parthasarathy, W. J. Tom, A. Gopal, X. Zhang, and A. K. Dunn,

Optics Express

(2008)

Normobaric hyperoxia improves cerebral blood flow and oxygenation, and inhibits peri-infarct depolarizations in experimental focal ischaemia

H. K. Shin, A. K. Dunn, P. B. Jones, D. A. Boas, E. H. Lo, M. A. Moskowitz, and C. Ayata,

Brain

(2007)

Peri-infarct depolarizations lead to loss of perfusion in ischaemic gyrencephalic cerebral cortex

A. J. Strong, P. J. Anderson, H. R. Watts, D. J. Virley, A. Lloyd, E. A. Irving, T. Nagafuji, M. Ninomiya, H. Nakamura, A. K. Dunn, and R. Graf,

Brain

(2007)

Vasoconstrictive neurovascular coupling during focal ischemic depolarizations

H. K. Shin, A. K. Dunn, P. B. Jones, D. A. Boas, M. A. Moskowitz, and C. Ayata,

Journal of Cerebral Blood Flow & Metabolism

(2006)

Evaluation of laser speckle flowmetry for imaging cortical perfusion in experimental stroke studies: quantitation of perfusion and detection of peri-infarct depolarisations

A. J. Strong, E. L. Bezzina, P. J. Anderson, M. G. Boutelle, S. E. Hopwood, and A. K. Dunn,

Journal of Cerebral Blood Flow & Metabolism

(2006)

Spatial extent of oxygen metabolism and hemodynamic changes during functional activation of the rat somatosensory cortex

A. K. Dunn, A. Devor, A. M. Dale, and D. A. Boas,

NeuroImage

(2005)

Determination of optimal exposure time for imaging of blood flow changes with laser speckle contrast imaging

S. Yuan, A. Devor, D. A. Boas, and A. K. Dunn,

Applied Optics

(2005)

Pronounced hypoperfusion during spreading depression in mouse cortex

C. Ayata, H. K. Shin, S. Salomone, Y. Ozdemir-Gursoy, D. A. Boas, A. K Dunn, and M. A. Moskowitz,

Journal of Cerebral Blood Flow & Metabolism

(2004)

Laser speckle flowmetry for the study of cerebrovascular physiology in normal and ischemic mouse cortex

C. Ayata, A. K. Dunn, Y. Gursoy-OZdemir, Z. Huang, D. A. Boas, and M. A. Moskowitz,

Journal of Cerebral Blood Flow & Metabolism

(2004)

Simultaneous imaging of total cerebral hemoglobin concentration, oxygenation, and blood flow during functional activation

A. K. Dunn, A. Devor, H. Bolay, M. L. Andermann, M. A. Moskowitz, A. M. Dale, and D. A. Boas,

Optics Letters

(2003)

Intrinsic brain activity triggers trigeminal meningeal afferents in a migraine model

H. Bolay, U. Reuter, A. K. Dunn, Z. Huang, D. A. Boas, M. A. Moskowitz,

Nature Medicine

(2002)

Dynamic imaging of cerebral blood flow using laser speckle

A. K. Dunn, H. Bolay, M. A. Moskowitz, and D. A. Boas,

Journal of Cerebral Blood Flow & Metabolism

(2001)

Using a webcam to perform LSCI

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.

Tracking perfusion after ischemic stroke

Multiple Exposure Speckle Imaging (MESI) used to track cerebral perfusion following an induced photothrombotic stroke. Green denotes areas of moderate flow deficit, while blue denotes areas of severe flow deficit.

Intraoperative Laser Speckle Contrast Imagery

Laser speckle contrast imagery acquired during neurosurgery with our intraoperative imaging system.