EPI Ghosting Checks

White Pixels

What to do: Run Echo Planar Image (EPI) White Pixel in the Head Coil and make sure you have no white pixels with the Transient Detection Module (TDM) disabled.

Why? White pixels during EPI Reference scan may cause failures in the linear and constant compensation, leading to artifacts in the final image.

Swap Phase/Frequency

What to do: Select the exact protocol that the customer is complaining about, except change the Phase/Frequency selection, and scan. If the ghosting is less, you may have a problem with the gradient axis that was originally used for phase encoding and you should check Grafidy and stability for that axis.

Grafidy

Verify that your Eddy Current compensation is done to the best possible level of compensation, for short, long, and very long time constants, on-axis and cross-terms.

Coherent Noise

Run System Performance Test (SPT) Coherent Noise Test and verify that no coherent noise is present on your system. Make sure TDM is not excessively blanking.

HSS

Run High Speed Stability (HSS) to make sure that environmental vibration or electrical disturbances (e.g. moving metal) are not the source of the ghosting problem.