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Estimation of magnetization transfer rates from PACE experiments with pulsed RF saturation
Author(s) -
Ropele Stefan,
Stollberger Rudolf,
Hartung HansPeter,
Fazekas Franz
Publication year - 2000
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/1522-2586(200011)12:5<749::aid-jmri13>3.0.co;2-2
Subject(s) - magnetization transfer , saturation (graph theory) , specific absorption rate , nuclear magnetic resonance , imaging phantom , materials science , analytical chemistry (journal) , nuclear medicine , physics , chemistry , optics , magnetic resonance imaging , mathematics , medicine , telecommunications , radiology , computer science , chromatography , combinatorics , antenna (radio)
A new imaging method has been developed for estimating the magnetization transfer rate (MTR) in a biologic two‐pool system such as the brain tissue. The transfer rate is calculated from the ratio of the MTR to T 1sat , where T 1sat is the apparent longitudinal relaxation time under complete saturation of the macromolecular pool. MTR and T 1sat maps were obtained with a phase acquisition of composite echo (PACE) technique combined with pulsed radiofrequency (RF) saturation. The influences of RF saturation power and frequency offset on quantitative results were investigated with phantom and in vivo measurements. In white matter of seven healthy volunteers we found a mean transfer rate of 1.5 sec −1 , where the highest transfer rate was found in the genu of the corpus callosum ( k f = 1.9 sec −1 ). It could be shown that conditions near to complete saturation can also be reached under common restrictions by the specific absorption rate. J. Magn. Reson. Imaging 2000;12:749–756. © 2000 Wiley‐Liss, Inc.