Determination of the trigger points. (a) Definition of trigger thresholds (black). As threshold value 90% of the local maxima of the cardiac signal (blue) is taken. As trigger points (red) always the first value above the threshold is chosen. (b) After definition of the trigger points (red) each read-out is assigned to a relative position in the heart cycle between 0 and 1 (black). Data during respiratory motion is gated out (relative position =-1). For projection selection the relative positions in the heart cycle were divided into 100 intervals (blue, displayed for 8 intervals).