Heterogeneity of Pulmonary Perfusion Characterized by Fractals and Spatial Correlations
New technologies providing high resolution measurements of organ perfusion, have revealed a large degree of spatial heterogeneity. These new observations provide new insights into the mechanisms of blood flow distribution and are revolutionizing our understanding of normal and pathologic physiology. The concepts of heterogeneity, as they apply to blood flow distribution, span all levels of physiology from the organ system to the mitochondrial level. Mechanisms matching heterogeneous perfusion to organ function and cellular needs encompass the same range of scales. New paradigms of organ perfusion and the matching of local blood flow to function are needed to account for these new observations. Fractal analysis, a revolutionary mathematical science, provides insights and tools for constructing such models. Because fractal analysis is not a familiar tool to most physiologic investigators, principal definitions and concepts will be systematically developed. Concurrently, numerical methods to determine whether a structure or process is fractal and to estimate a fractal dimension will be derived.
KeywordsFractal Dimension Spatial Correlation Fractal Analysis Pulmonary Blood Flow Pulmonary Perfusion
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