RadioProcessor-G
Tips on obtaining data using the gradient echo example
There are multiple Windows script (batch) files along with the gradient echo example program that can be
used to check scan parameters without doing an entire MRI pulse sequence with multiple phase amplitudes.
FID
FID.bat has delays and acquisition parameters set by default to aid in inspecting the FID. The FID is seen
using this pulse program by turning off all of the gradients, shortening the phase delay time and the gradient
echo delay time, setting the number of points to a large number, increasing the spectral width, and reducing
the number of phases to 1. By inspecting the FID, you can find an approximate value for T2* which will
determine how long of a delay you can program before your expected gradient echo.
FID_Readout
FID_Readout.bat has delays and acquisition parameters set by default to aid in inspecting a single gradient
echo. This is best used to make sure that your acquisition parameters are sufficient for a full MRI scan. By
running a single phase of the full MRI scan, you can check a single echo to make sure it looks good before
continuing. When running this batch, make sure you have your readout gradient on and your phase gradient
off.
To get a good signal, make sure to set acquisition parameters (
nPoints
and
spectralWidth_kHz
) so
the acquisition period is centered on a point in time that still has a strong signal in the FID example. Select a
phase_time
parameter that corresponds to one half of the time from the end of the RF pulse to the desired
center of acquisition. That will set the amplitude of the readout gradient to approximately -1.0 for dephasing,
and 1.0 for phasing resulting in the strongest echo possible.
2017-09-04
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