title: Incidental magnetization transfer contrast by fat saturation preparation pulses in multislice Look-Locker echo planar imaging.
abstract: In this study, it is demonstrated that fat saturation (FS) preparation (prep) pulses generate incidental magnetization transfer contrast (MTC) in multislice Look-Locker (LL) imaging. It is shown that frequency-selective FS prep pulses can invoke MTC through the exchange between free and motion-restricted protons. Simulation reveals that the fractional signal loss by these MTC effects is more severe for smaller flip angles (FAs), shorter repetition times (TRs), and greater number of slices (SN). These incidental MTC effects result in a signal attenuation at a steady state (up to 30%) and a T(1) measurement bias (up to 20%) when using inversion recovery (IR) LL echo-planar imaging (EPI) sequences. Furthermore, it is shown that water-selective MRI using binomial pulses has the potential to minimize the signal attenuation and provide unbiased T(1) measurement without fat artifacts in MR images.
authors.affiliation: Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA. shinwa@nida.nih.gov
authors.forename: Wanyong
authors.initials: W
authors.lastname: Shin
authors.forename: Hong
authors.initials: H
authors.lastname: Gu
authors.forename: Yihong
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D000465:Algorithms; D019412:Anatomy, Cross-Sectional / Q000379:methods*; D001921:Brain / Q000033:anatomy & histology*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013382:Subtraction Technique