Title
Quantitative magnetization transfer imaging of human brain at 7 T.
Abstract
Quantitative magnetization transfer (qMT) imaging yields indices describing the interactions between free water protons and immobile macromolecular protons. These indices include the macromolecular to free pool size ratio (PSR), which has been shown to be correlated with myelin content in white matter. Because of the long scan times required for whole-brain imaging (≈20–30min), qMT studies of the human brain have not found widespread application. Herein, we investigated whether the increased signal-to-noise ratio available at 7.0T could be used to reduce qMT scan times. More specifically, we developed a selective inversion recovery (SIR) qMT imaging protocol with a i) novel transmit radiofrequency (B1+) and static field (B0) insensitive inversion pulse, ii) turbo field-echo readout, and iii) reduced TR. In vivo qMT data were obtained in the brains of healthy volunteers at 7.0T using the resulting protocol (scan time≈40s/slice, resolution=2×2×3mm3). Reliability was also assessed in repeated acquisitions. The results of this study demonstrate that SIR qMT imaging can be reliably performed within the radiofrequency power restrictions present at 7.0T, even in the presence of large B1+ and B0 inhomogeneities. Consistent with qMT studies at lower field strengths, the observed PSR values were higher in white matter (mean±SD=17.6±1.3%) relative to gray matter (10.3±1.6%) at 7.0T. In addition, regional variations in PSR were observed in white matter. Together, these results suggest that qMT measurements are feasible at 7.0T and may eventually allow for the high-resolution assessment of changes in composition throughout the normal and diseased human brain in vivo.
Year
DOI
Venue
2013
10.1016/j.neuroimage.2012.08.047
NeuroImage
Keywords
Field
DocType
Magnetization transfer,7T,White matter,Myelin,Brain,Multiple sclerosis
White matter,Cognitive psychology,Psychology,Pulse (signal processing),Human brain,Magnetization transfer,Magnetization transfer imaging,Nuclear magnetic resonance,Pathology,Magnetic resonance imaging
Journal
Volume
ISSN
Citations 
64
1053-8119
7
PageRank 
References 
Authors
0.53
6
8
Name
Order
Citations
PageRank
Richard D. Dortch1101.32
Jay Moore270.53
Ke Li370.53
Marcin Jankiewicz470.53
Daniel F. Gochberg5362.87
Jane A. Hirtle670.53
John C Gore761641.36
Seth A. Smith81137.51