EPI Ghosting Checks

White Pixels

What to do: Run EPI White Pixel in the Head Coil and make sure you have no white pixels with the TNS 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 protocol that the customer is complaining about, change the Phase/Frequency selection, and scan. If the ghosting is less, you 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, both for long and very long time constants, on-axis and cross-terms. Short time constant compensation should not be run, as it is not expected to yield better results than the system defaults.

Coherent Noise

Run SPT Coherent Noise Test and verify that no coherent noise is present on your system.

HSS

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