leoliuf / MRiLab

A Numerical Magnetic Resonance Imaging (MRI) Simulation Platform
https://leoliuf.github.io/MRiLab/
BSD 2-Clause "Simplified" License
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K-space #20

Closed FZihan closed 5 years ago

FZihan commented 5 years ago

In sequence design panel I chose GzSelective at the same time with RF pulse, with TE=5.5, default CVs, GzRamp=100e-6 and GzAmp 1e-4 After plotting the k-space I gain an oblique shape of it, but if set the GzAmp=7e-4 I get a correct k-space parallel to Kx- Ky plane. I have attached these images for you May I ask you to tell me, why I gained these kinds of images just by changing the GzAmp? Where is the problem?

seq

k1

Answer: There is an extended event (on Ext line) to reset k space location to zero before the imaging gradient. The offset might be caused because GzSelective gradient is not reset properly in the calculating of k space location. You can simply change the Ext event time to be after GzSelective and before the regular imaging gradients. For more information, please see user manual 5.2.8. Thanks.

https://leoliuf.github.io/MRiLab/manual/MRiLab_User_Guide_v1_3/MRiLab_User_Guide.html