Example of correct ECG trigger detection. Cardiac images, trigger detection tickmarks and signal waveforms obtained at 7.0 T using vector ECG (left), pulse oximetry (center) and acoustically triggered (right) 2D CINE FLASH acquisitions. All signal waveforms show the output of the scanners central physiological monitoring unit (including processing of the ECG, POX and ACT signal) as displayed at the scanners user interface. Top: Mid-ventricular, short axis views of the heart together with whole R-R interval time series of one-dimensional projections along the profile (dotted line) marked in the short axis view. Middle: Trigger detection tickmarks obtained from a single subject over 18 cardiac cycles after temporal realignment using cross correlation and reassignment. Bottom: Signal waveforms obtained from a single subject (subject 1) over 18 cardiac cycles. In spite of vector ECG's severe signal distortion faultless vector ECG triggering was observed for this example. Hence, in this example of correct recognition of the onset of cardiac activity, vector ECG, POX and ACT triggered 2D CINE FLASH imaging were found to be immune to the effects of cardiac motion. Please note the jitter in the vector ECG (Δt = 60 ms) and in the pulse oximetry trigger (Δt = 65 ms)detection.Source: Cardiac Chamber quantification using magnetic resonance imaging at 7 Tesla--a pilot study Florian von Knobelsdorff-Brenkenhoff et al.; European Radiology, 20(12): 2844-52; 2010