Premium
Suppression of effects of gradient imperfections on imaging with alternate ascending/descending directional navigation
Author(s) -
Park SungHong,
Zhao Tiejun,
Kim JungHwan,
Boada Fernando E.,
Bae Kyongtae Ty
Publication year - 2012
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.24169
Subject(s) - subtraction , imaging phantom , signal (programming language) , physics , background subtraction , nuclear magnetic resonance , computer science , biomedical engineering , materials science , optics , mathematics , pixel , medicine , arithmetic , programming language
Abstract Alternate ascending/descending directional navigation (ALADDIN) is a new imaging technique that provides interslice perfusion‐weighted and magnetization transfer (MT) asymmetry images. In this article, we investigated the effects of gradient imperfections on ALADDIN MT asymmetry (MTA) signals. Subtraction artifacts increasing with readout offsets were detectable in ALADDIN MTA images from an agarose phantom but not from a water phantom. Slice‐select offsets had no significant effect on the artifacts in MTA. The artifacts were suppressed by averaging signals over the readout gradient polarities independent of scan parameters. All these results suggested that the subtraction artifacts were induced by readout eddy currents. With suppression of the artifacts, ALADDIN signals in human brain and skeletal muscle varied less with scan conditions. Percent signal changes of MTA in human skeletal muscle (0.51 ± 0.11%, N = 3) were about 30% of those in white matter. The new averaging scheme will allow for more accurate MTA imaging with ALADDIN, especially at off‐center positions. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.