Diagnostic angiograms only provide the projected lumen of a coronary, which is only an indirect measure of blood flow and pressure decline. According to an exemplary embodiment of the present invention, a motion compensated determination of a flow dynamics and a pressure decline for stenosis grading is provided, in which the motion compensation is performed on the basis of a tracking of a first position of a first marker and a second position of a second marker in the projection data set. This may provide for a robust and precise flow dynamics and pressure decline determination.