“…This model is given as (27) where , are the indices of the voxels in the neighborhood of the th voxel; , are the spatial weighting coefficients, which may be different for each pharmacokinetic-rate or volume fraction image; and , is a zero-mean Gaussian process with , . The weighting coefficients may be spatially varying and can be chosen based on a variety of physiological information, i.e., tumor location, size, or shape.…”