1. A method for functional visualization and localization of an arteriovenous malformation with an X-ray tomographic examination by a rotatable imaging system, comprising: scanning a patient in an examination region containing the arteriovenous malformation by the rotatable imaging system; generating a plurality of projections at different projection angles over a predetermined projection angle range during a contrast agent uptake time; subdividing the plurality of projections into at least three partial projection datasets comprising cohesive partial projection angle ranges, wherein projections in each partial projection dataset belong to different consecutive time windows during the scan; reconstructing a time series of tomosynthesis image datasets each from the projections in each partial projection dataset using a digital tomosynthesis method, and determining vessels flooded by the contrast agent in each of the different consecutive time windows from the time series of the tomosynthesis image datasets, wherein vessels flooded first are assigned to arterial vessels and vessels flooded last are assigned to venous vessels.