title: Quantitative T1 and proton density mapping with direct calculation of radiofrequency coil transmit and receive profiles from two-point variable flip angle data.
abstract: Quantitative T1 mapping of brain tissue is frequently based on the variable flip angle (VFA) method, acquiring spoiled gradient echo (GE) datasets at different excitation angles. However, accurate T1 calculation requires a knowledge of the sensitivity profile B1 of the radiofrequency (RF) transmit coil. For an additional derivation of proton density (PD) maps, the receive coil sensitivity profile (RP) must also be known. Mapping of B1 and RP increases the experiment duration, which may be critical when investigating patients. In this work, a method is presented for the direct calculation of B1 and RP from VFA data. Thus, quantitative maps of T1 , PD, B1 and RP can be obtained from only two spoiled GE datasets. The method is based on: (1) the exploitation of the linear relationship between 1/PD and 1/T1 in brain tissue and (2) the assumption of smoothly varying B1 and RP, so that a large number of data points can be fitted across small volume elements where B1 and RP are approximately constant. The method is tested and optimized on healthy subjects. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Brain Imaging Center, Goethe University Frankfurt, Frankfurt/Main, Germany.|Department of Neurology, Goethe University Frankfurt, Frankfurt/Main, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Baudrexel
authors.affiliation: Brain Imaging Center, Goethe University Frankfurt, Frankfurt/Main, Germany.|Department of Neurology, Goethe University Frankfurt, Frankfurt/Main, Germany.
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Reitz
authors.affiliation: Brain Imaging Center, Goethe University Frankfurt, Frankfurt/Main, Germany.|Department of Neurology, Goethe University Frankfurt, Frankfurt/Main, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hof
authors.affiliation: Brain Imaging Center, Goethe University Frankfurt, Frankfurt/Main, Germany.|Department of Neurology, Goethe University Frankfurt, Frankfurt/Main, Germany.
authors.forename: René-Maxime
authors.initials: RM
authors.lastname: Gracien
authors.affiliation: Department of Neurology, Johannes Gutenberg University, Mainz, Germany.|Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg University, Mainz, Germany.
authors.forename: Vinzenz
authors.initials: V
authors.lastname: Fleischer
authors.affiliation: Department of Neurology, Johannes Gutenberg University, Mainz, Germany.|Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg University, Mainz, Germany.
authors.forename: Hilga
authors.initials: H
authors.lastname: Zimmermann
authors.affiliation: Department of Neurology, Johannes Gutenberg University, Mainz, Germany.|Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg University, Mainz, Germany.
authors.forename: Amgad
authors.initials: A
authors.lastname: Droby
authors.affiliation: Brain Imaging Center, Goethe University Frankfurt, Frankfurt/Main, Germany.|Department of Neurology, Goethe University Frankfurt, Frankfurt/Main, Germany.
authors.forename: Johannes C
authors.initials: JC
authors.lastname: Klein
authors.affiliation: Brain Imaging Center, Goethe University Frankfurt, Frankfurt/Main, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Deichmann
mesh_terms: D000328:Adult; D003198:Computer Simulation; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D011522:Protons; D011846:Radio Waves
chemical_list: D011522:Protons
keywords: B1 mapping; T1 mapping; proton density; quantitative MRI (qMRI); radiofrequency (RF); receive sensitivity; transmit sensitivity; water content