Quantitative description of the asymmetry in magnetization transfer effects around the water resonance in the human brain.
Magnetization transfer (MT) imaging provides a unique method of tissue characterization by capitalizing on the interaction between solid-like tissue components and bulk water. We used a continuous-wave (CW) MT pulse sequence with low irradiation power to study healthy human brains in vivo at 3 T and quantified the asymmetry of the MT effects with respect to the water proton frequency. This asymmetry was found to be a difference of approximately a few percent from the water signal intensity, depending on both the RF irradiation power and the frequency offset. The experimental results could be quantitatively described by a modified two-pool MT model extended with a shift contribution for the semisolid pool with respect to water. For white matter, this shift was fitted to be 2.34 +/- 0.17 ppm (N = 5) upfield from the water signal.
Hua
Jun
J
Department of Radiology, Division of MRI Research, Neurosection, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2109, USA.
Jones
Craig K
CK
Blakeley
Jaishri
J
Smith
Seth A
SA
van Zijl
Peter C M
PC
Zhou
Jinyuan
J
D001921:Brain / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D011522:Protons; D014867:Water
D011522:Protons; D014867:Water