Fig. 4
Representative blood flow velocity waveforms in ascending aorta with corresponding power spectra, cross-sectional velocity maps, and dynamic time warp distance. Top Row: Blood velocity waveforms (left) with S2 PC-CMR from patients with heart rate of 63 bpm (10th percentile) and 103 bpm (90th percentile), corresponding power spectra (center), and cumulative sum of power spectra (right) with the dotted vertical lines indicating the frequency below which 99% of the total signal energy of the waveform is contained, 7.5 Hz and 13.3 Hz respectively. Middle row: Pixel-wise velocity maps in ascending aorta for patient number 20 with different acceleration factors. Bottom row: mean blood flow velocity waveforms (left) associated with the middle row, dynamic time warp distance and fmax99 (center), and heart rate, mean peak velocity, net flow, and cardiac output (right) for each PC-CMR scan. CS3,4,5,6 = C-SENSE acceleration factor of 3,4,5,6, DTW Dist = dynamic time warp distance, fmax99 = frequency below which 99% of the total signal energy of the waveform is contained, S2 = SENSE acceleration factor of 2, Ejection period = foot-to-foot distance in ascending aortic blood waveform