Appendix E
Example Waveforms
Revision C, August 2013
E-1
This appendix presents the following waveform examples collected in the MR
environment:
1. Mouse outside the MR magnet
2. Mouse with E-Resp™ cradle in 7.0 T
3. Mouse with E-Resp™ cradle in 7.0 T, ECG and respiratory gated spin
echo sequence
Examples 1 and 2 exhibit how important temperature is on the physiology of the mouse
and the effect of the strong static magnetic field on the ECG waveform.
Examples 1 and 2 were acquired with the same mouse and the same preparation.
Example 2 was acquired thirty minutes after example 1. In that length of time the
temperature of the mouse, which was not being regulated, dropped nearly 5
o
C. With
the drop in temperature the heart rate also decreased from 473 to 302 BPM.
Comparison of the ECG waveforms shows the signal contributions from flowing blood
and from respiration. In this case we increased the respiration signal by intentionally
coupling one of the ECG leads to the mouse’s abdomen using an E-Resp™ cradle.
Example 3 shows us how to interpret scanner operation by observing the ECG
waveform. Gradient interference is observed after each gate and we can clearly see
the data acquisition time intervals for each slice in the sequence.
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