Shimming - josalggui/MaRGE GitHub Wiki
This sequence sweeps the offset on the gradient to determine the optimal shimming by evaluating the spectrum amplitude and Full Width at Half Maximum (FWHM).
Parameters:
-
nPoints
: Number of points to be acquired in each acquisition window. -
Larmor frequency offset (kHz)
: Frequency offset in kHz relative to the calibrated Larmor frequency found inlarmorFreq
inconfigs/hw_config.py
. -
Excitation flip angle (º)
: RF excitation pulse flip angle in degrees. -
Refocusing flip angle (º)
: RF refocusing pulse flip angle in degrees. -
RF excitation time (us)
: RF excitation pulse duration in microseconds. -
RF refocusing time (us)
: RF refocusing pulse duration in microseconds. -
Echo time (ms)
: Time from the excitation to the echo in milliseconds. -
Repetition time (ms)
: Time between excitations in milliseconds. -
Acquisition time (ms)
: Duration of the acquisition window. -
Dummy pulses
: Number of dummy pulses. -
Shimming
: Center values for the shimming sweep. -
n Shimming steps
: Number of shimming values to sweep per channel. -
Shimming step
: Step values for the sweep.
After running the sequence, the optimal shimming values are displayed in the console and applied to all subsequent sequences.