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AssigneeGeneral Electric Company
InventorsXiaohong Zhou, Joseph K. Maier, Frederick H. Epstein
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In a magnetic resonance imaging (MRI) system, a method is provided for reducing oblique Nyquist ghost artifact in an image produced by an oblique EPI scan. Prior to commencing the EPI scan, referencing pre-scans are conducted to generate pre-scan echo trains respectively corresponding to the physical gradient axes. Distortion compensating parameters are derived from the pre-scan echo trains for reducing Nyquist ghost by alternatively modifying the data acquisitions stage of the oblique EPI scan, or the post-data acquisition image processing stage thereof. In one mode of operation, the pre-scan echo trains are generated while a subject is in the MRI system. In another mode of operation, pre-scan echo trains are generated while no subject is present in the MR system, so that the distortion compensating parameters represent characteristics of the MR system only, and thus may be used for EPI scans of different protocols. For such mode of operation the distortion compensating parameters may be computed as a function of readout gradient pulse spacing.
In an MR system having a plurality of gradient coils and operated in accordance with an EPI scan technique to provide an oblique image of a subject, wherein said scan technique includes the steps of acquiring a series of EPI echoes, and then processing said acquired echoes to provide said oblique image, and wherein gradient waveforms respectively produced by said gradient coils can be distorted differently from one another, an artifact correction method comprising:
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