A recent theoretical framework using power-law functions was proposed to model scattering from biological tissues in ultrasound and optical coherence tomography. Multi-scale scattering sites such as the fractal branching vasculature will then contribute to power-law based probability distributions of speckle statistics. These distributions are the Burr type XII distribution, the Lomax distribution, and the generalized logistic distribution for speckle amplitude, intensity, and log amplitude, respectively. Previous experiments with ultrasound and optical coherence tomography demonstrate that these distributions are better fits to image histogram data of various biological tissues when compared with classical models (e.g., Rayleigh, K, and gamma distributions). Of critical importance is that this framework provides novel parameters, most notably the power-law exponent parameter, for characterizing the physics of scattering from soft tissue. The typical range for the exponent parameter in other normal tissues is approximately 3 to 6. The aim is for this parameter to be used as a new biomarker for diagnostic imaging, sensitive to changes in tissue structures. Here, we demonstrate a specific application to mouse brain tissue, in which the exponent parameter is used to characterize mouse cortical brain under various conditions including ex vivo and in vivo using optical coherence tomography.
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