A computer-based method of determining a functional assessment of at least one organ having secretional or excretional functions, such as a liver or kidneys, of a human is disclosed. The method comprises processing a four-dimensional (4D) image data set of said human comprising data for an assessment of said organ function, wherein said 4D image data is acquired by an image modality and wherein said processing said 4D image data comprises performing a deconvolutional analysis (DA) comprising a matrix inversion using singular value decomposition (SVD) based on said 4D image data.
