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Robust EPI Nyquist Ghost Elimination via Spatial and Temporal Encoding
Institution:
 1Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
2Virginia Tech - Wake Forest University School of Biomedical Engineering and Sciences, Winston-Salem, NC
Publisher:
 John Wiley & Sons, Inc.
Publication Date:
 Dec-2010
Journal:
 Magn Reson Med
Volume Number:
 64
Issue Number:
 6
Pages:
 1781-91
Citation:
 Magn Reson Med. 2010 Dec;64(6):1781-91.
PubMed ID:
 20665898
PMCID:
 PMC3038256
Keywords:
 EPI artifacts, ASLPerfusion Imaging, N/2 ghost correction, GRAPPA
Appears in Collections:
NCIGT, MIPG
Sponsors:
 NIH P41 RR019703
NIH R01 AA-016748-02
Generated Citation:
 Hoge W.S., Tan H., Kraft R.A. Robust EPI Nyquist Ghost Elimination via Spatial and Temporal Encoding. Magn Reson Med. 2010 Dec;64(6):1781-91. PMID: 20665898. PMCID: PMC3038256.
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Nyquist ghosts are an inherent artifact in echo planar imaging acquisitions. An approach to robustly eliminate Nyquist ghosts is presented that integrates two previous Nyquist ghost correction techniques: temporal domain encoding (phase labeling for additional coordinate encoding: PLACE and spatial domain encoding (phased array ghost elimination: PAGE). Temporal encoding modulates the echo planar imaging acquisition trajectory from frame to frame, enabling one to interleave data to remove inconsistencies that occur between sampling on positive and negative gradient readouts. With PLACE, one can coherently combine the interleaved data to cancel residual Nyquist ghosts. If the level of ghosting varies significantly from image to image, however, the signal cancellation that occurs with PLACE can adversely affect SNR-sensitive applications such as perfusion imaging with arterial spin labeling. This work proposes integrating PLACE into a PAGE-based reconstruction process to yield significantly better Nyquist ghost correction that is more robust than PLACE or PAGE alone. The robustness of this method is demonstrated in the presence of magnetic field drift with an in-vivo arterial spin labeling perfusion experiment.

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