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Shimming
José Miguel Algarín edited this page Jan 14, 2025
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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:
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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 inlarmorFreqinconfigs/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.