Skip to main content
. Author manuscript; available in PMC: 2015 Nov 1.
Published in final edited form as: Magn Reson Med. 2014 Sep 12;72(5):1208–1217. doi: 10.1002/mrm.25450

Figure 2.

Figure 2

(a) Cardiac principal components at different sampling rates with the reference ECG waveform, displayed on a common time axis. The vertical lines indicate the ECG R-wave triggers, and the circles on the SG waveform indicate the SG trigger times from valley detection. Comparing the two, cardiac SG performed reliably for sampling rates as low as 4.0 Hz. Lower rates led to inaccuracy in trigger times and missed trigger, as indicated by the two cardiac SG waveforms sampled at 3.0 Hz and lower. (b) The uncertainty in the SG trigger times was measured by the standard deviation (SD) of the difference between SG and ECG trigger times. The SD value remained low for sampling rates above 3.0 Hz and drastically increased at 2.8 Hz. Lower sampling rates resulted in missing triggers, thus the SD was not calculated.