Example Waveforms
Revision C, August 2013
E-4
Mouse with E-Resp™ cradle in 7.0 T MR
ECG & respiratory gated spin echo sequence
This example, which does not show the best way to make gated images, is a good
example of observing MR scanner operation from interference in the ECG waveform.
The measured ECG waveform has signals superimposed from respiration, blood flow
and pulsed magnetic field gradients.
A gate for the MR scanner is generated by the first R-wave after detection of inspiration.
The gate initiates MR scanner data acquisition for three images (slices). The gradient
interference for a single slice lasts about 50 msec and the acquisition time between
images is 130 msec. It is easy to conclude, from gradient interference present in the
ECG waveform, that three images are being acquired during the respiratory cycle but
not during the same cardiac cycle.
Note sometimes R-waves do not fall inside (coincide with) the inspiration window and
therefore gates are not sent to the MR scanner.
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