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A new ultrafast 3D gradient echo‐based imaging method using quadratic‐phase encoding
Author(s) -
Ryu JaeKyun,
Han SoHyun,
Oh SeHong,
Lee Joonsung,
Kim SeongGi,
Park JangYeon
Publication year - 2019
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.27711
Subject(s) - imaging phantom , quadratic equation , nuclear magnetic resonance , robustness (evolution) , ultrashort pulse , physics , phase (matter) , spin echo , computer science , encoding (memory) , algorithm , sensitivity (control systems) , biological system , optics , magnetic resonance imaging , mathematics , chemistry , artificial intelligence , biology , electronic engineering , medicine , laser , biochemistry , geometry , radiology , quantum mechanics , gene , engineering
Purpose To propose a novel 3D ultrafast gradient echo‐based MRI method, dubbed RASE, using quadratic‐phase encoding. Theory and Methods Several characteristics of RASE, including spin behaviors, spatial resolution, SNR, and reduction of susceptibility‐induced signal loss, were analytically described. A way of compensating for TE variation was suggested in the quadratic phase‐encoding direction. Lemon, in vivo rat and mouse images were demonstrated at 9.4T, including a feasibility study for DCE‐MRI as one of promising applications. Results RASE was successfully demonstrated by lemon and in vivo rat brain imaging, showing a good robustness to field inhomogeneity. Contribution of the quadratic phase to signal enhancement in a range of magnetic susceptibilities was also evaluated by simulation. Taking a geometric mean of 2 phantom data acquired with opposite gradient polarities effectively compensated for the effect of TE variation. Preliminary DCE‐MRI results were also presented, showing that RASE could more accurately estimate Gd concentration than FLASH. Conclusion RASE offers a shorter effective TE, having less sensitivity to field inhomogeneity and T 2 * effects, much less Nyquist ghosting or chemical‐shift artifacts than gradient echo EPI (GE‐EPI). We highly anticipate that RASE can be an alternative to GE‐EPI in many applications, particularly those requiring high spatial and temporal resolutions in a broad volume coverage.