The invention relates to a processing apparatus for processing cardiac data of a living being and to an imaging system comprising the processing apparatus. A distribution of Fractional flow reserve (FFR) values being indicative of the FFR of different coronary arteries of the living being, a distribution of myocardial perfusion values like values of an iodine map being indicative of the myocardial perfusion of different portions of the myocardium of the living being and assignments between coronary arteries and portions of the myocardium of the living being are used for determining degrees of correspondence between FFR values and myocardial perfusion values. This allows for, for example, a determination of the reliability of the FFR values, if the myocardial perfusion values are known to be reliable, based on the determined degrees of correspondence.
