Method for generating contrast agent concentration map from a non-contrast enhanced computed tomography scan, a contrast enhanced computed tomography scan and corresponding spectral computed tomography data, comprising: a. generating at least two different primary contrast agent concentration maps out of the non-contrast enhanced Computed Tomography scan, the contrast enhanced Computed Tomographyscan and the spectral Computed Tomography data, b. performing a local quality analysis of each primary contrast agent concentration map c. Determining local volumetric weights for each primary contrast agent concentration map based on the local quality analysis, and d. generating a secondary contrast agent concentration map based on the two primary contrast agent concentration maps and on their corresponding local volumetric weights.