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Abstract

System and method for the localization of functional activity in the human brain during neurosurgery. The system includes an electronic flash illuminator for illuminating the surface of the exposed portion of the patient's brain, optical bandpass filters for sequentially illuminating the exposed brain surface with monochromatic light of a number of predetermined wavelengths, a positioning mechanism for rapid positioning of the optical filters in the path of illumination, a video camera for acquiring an image of the exposed brain surface during illumination with each wavelength of monochromatic light, a circuit for converting the linear output signal of the video camera into a logarithmic signal in video format, a digitizer and frame storage memory for digitizing the logarithmic video signal to obtain multiple two-dimensional matrices. Each matrix represents the magnitude of light reflected at a particular wavelength from a regular grid of points over the exposed brain surface. The system also includes a video frame arithmetic circuit for computing two-dimensional matrices of regional total hemoglobin concentration utilizing the two-dimensional matrices of reflectance data and for transforming the computed matrices into gray-scale or color-scale maps representing total hemoglobin concentration at the grid of points on the exposed brain surface, and a circuit for displaying, on a high-resolution RGB color video monitor, gray-scale or color-scale maps representing either absolute total hemoglobin concentration over the exposed brain surface at a single point in time or the difference between total hemoglobin concentration on the exposed brain surface before and after functional activation of the brain. Functional activation of the brain is accomplished by applying a sensory stimulus to the patient or by having the patient perform a cognitive task in a neuropsychological paradigm appropriately modified for the neurosurgical setting.

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First Claim