Yuck, my oblique EPI scans have huge ghosts in them. Whats going on?
This is a problem that GE knows about, and occurs when the readout gradient is using the z-gradient in combination with one of the other gradients. If you’re just using the z-gradient by itself (e.g. pure coronal or saggital), ghosting appears to be minimal. There are two things you can do. 1) You can set the research control variable (CV) rhpcspacial equal to zero. This will make the EPI prescan a little longer, but significantly diminishes ghosting for slices that are off-isocenter. (2) You can set the readout (frequency) direction to be left-right instead of anterior-posterior or superior-inferior. This way the readout gradient doesn’t use the z-gradient. If you are doing an oblique axial that is less than 45 degrees from horizontal, then left-right is the default readout direction and you should be okay. However, if you’re oblique axial is more than 45 degrees from axial, the scanner picks superior-inferior as the default direction. In that case, you would change the Frequency Box
