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Reducing flow artifacts in echo‐planar imaging
Author(s) -
Pat Gerard T. Luk,
Meyer Craig H.,
Pauly John M.,
Nishimura Dwight G.
Publication year - 1997
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910370323
Subject(s) - k space , flyback transformer , flow (mathematics) , fourier transform , echo planar imaging , computer science , planar , fourier analysis , nuclear magnetic resonance , echo (communications protocol) , acoustics , physics , magnetic resonance imaging , mechanics , mathematics , mathematical analysis , medicine , voltage , computer network , computer graphics (images) , quantum mechanics , radiology , transformer
Echo‐planar imaging (EPI) is very susceptible to flow artifacts. Two ways to improve its flow properties are presented. First, “partial flyback” is proposed to reduce artifacts arising from flow in the readout direction. Near the center of k ‐space, only the even echoes of the EPI echo‐train are used. Partial flyback is shown to improve the readout‐flow properties at the expense of a slight worsening of the phase‐encode flow and off‐resonance properties. We recommend that the flyback region acquire 95% of the energy in k ‐space. Second, “inside‐out” EPI is used to reduce artifacts arising from flow in the phase‐encode direction. Data collection begins at the center of k ‐space, with separate interleaves to acquire the top and bottom halves of k ‐space. Partial flyback is combined with partial‐Fourier EPI and inside‐out EPI. Partial‐flyback inside‐out EPI has worse off‐resonance properties than partial‐flyback partial‐Fourier EPI but demonstrates better flow properties and does not require partial k ‐space reconstruction.