Abstract: An image processing apparatus for computing a quantitative imaging biomarker (QIB) of disease severity from variations in texture-based features in a tomographic image, the apparatus including a first preprocessing module for normalizing the intensities in the tomographic image; a second identification module for identifying at least one organ of interest in the tomographic image; a third ROI selection module for identifying and selecting a plurality of target ROIs and reference ROIs representative respectively of abnormal and normal pathology in the organ(s) of interest; a fourth ROI assessment module for extracting a plurality of texture-based feature signatures from the target ROIs and the reference ROIs, wherein the feature signatures are generated from distributions of statistical attributes extracted from each ROI; a fifth biomarker assessment module for computing the distance between the target ROI signatures and the reference ROI signatures, wherein the biomarker of disease severity is a function of t