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Research Papers

Imaging cortical absorption, scattering, and hemodynamic response during ischemic stroke using spatially modulated near-infrared illumination

[+] Author Affiliations
David Abookasis

University of California Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road East, Irvine, California 92612

Christopher C. Lay

University of California Irvine, Department of Neurobiology and Behavior, 2205 McGaugh Hall, Irvine, California 92697

Marlon S. Mathews, Mark E. Linskey

University of California Irvine, Department of Neurological Surgery, Medical Center, 101 The City Drive South, Orange, California 92868

Ron D. Frostig

University of California Irvine, Department of Neurobiology and Behavior, 2205 McGaugh Hall, Irvine, California 92697

Bruce J. Tromberg

University of California Irvine, Beckman Laser Institute and Medical Clinic, 1002 Health Sciences Road East, Irvine, California 92612

J. Biomed. Opt. 14(2), 024033 (June 04, 2008January 13, 2009February 11, 2009April 29, 2009). doi:10.1117/1.3116709
History: Received June 04, 2008; Revised January 13, 2009; Accepted February 11, 2009; Published April 29, 2009
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We describe a technique that uses spatially modulated near-infrared (NIR) illumination to detect and map changes in both optical properties (absorption and reduced scattering parameters) and tissue composition (oxy- and deoxyhemoglobin, total hemoglobin, and oxygen saturation) during acute ischemic injury in the rat barrel cortex. Cerebral ischemia is induced using an open vascular occlusion technique of the middle cerebral artery (MCA). Diffuse reflected NIR light (680to980nm) from the left parietal somatosensory cortex is detected by a CCD camera before and after MCA occlusion. Monte Carlo simulations are used to analyze the spatial frequency dependence of the reflected light to predict spatiotemporal changes in the distribution of tissue absorption and scattering properties in the brain. Experimental results from seven rats show a 17±4.7% increase in tissue concentration of deoxyhemoglobin and a 45±3.1, 23±5.4, and 21±2.2% decrease in oxyhemoglobin, total hemoglobin concentration and cerebral tissue oxygen saturation levels, respectively, 45min following induction of cerebral ischemia. An ischemic index (Iisch=ctHHbctO2Hb) reveals an average of more then twofold contrast after MCAo. The wavelength-dependence of the reduced scattering (i.e., scatter power) decreased by 35±10.3% after MCA occlusion. Compared to conventional CCD-based intrinsic signal optical imaging (ISOI), the use of structured illumination and model-based analysis allows for generation of separate maps of light absorption and scattering properties as well as tissue hemoglobin concentration. This potentially provides a powerful approach for quantitative monitoring and imaging of neurophysiology and metabolism with high spatiotemporal resolution.

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© 2009 Society of Photo-Optical Instrumentation Engineers

Citation

David Abookasis ; Christopher C. Lay ; Marlon S. Mathews ; Ron D. Frostig ; Bruce J. Tromberg, et al.
"Imaging cortical absorption, scattering, and hemodynamic response during ischemic stroke using spatially modulated near-infrared illumination", J. Biomed. Opt. 14(2), 024033 (June 04, 2008January 13, 2009February 11, 2009April 29, 2009). ; http://dx.doi.org/10.1117/1.3116709


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