title: Diffusion-weighted DESS protocol optimization for simultaneous mapping of the mean diffusivity, proton density and relaxation times at 3 Tesla.
abstract: To design a general framework for the optimization of an MRI protocol based on the the diffusion-weighted dual-echo steady-state (DW-DESS) sequence, enabling quantitative and simultaneous mapping of proton density (PD), relaxation times T1 and T2 and diffusion coefficient D.
  
  
  
  A parameterization of the DW-DESS sequence minimizing the Cramér-Rao lower bound of each parameter estimate was proposed and tested in a phantom experiment. An extension of the protocol was implemented for brain imaging to return the rotationally invariant mean diffusivity (MD).
  
  
  
  In an NiCl2-doped agar gel phantom wherein T1/T2=920/65 ms, the parameter estimation errors were below 3% for PD and T1 and below 7% for T2 and D while the measured signal-to-noise ratio always exceeded 20. In the human brain, the in vivo parametric maps obtained were overall in reasonable agreement with gold standard measurements, despite a broadening of the distributions due to physiological motion.
  
  
  
  Within the optimization framework presented here, DW-DESS images can be quantitatively interpreted to yield four intrinsic parameters of the tissue. Currently, the method is limited by the sensitivity of the DW-DESS sequence in terms of physiological motion. Magn Reson Med 78:130-141, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Institute of Neuroscience and Medicine - 4, Medical Imaging Physics, Forschungszentrum Jülich GmbH, Jülich, Germany.|UNIRS, Institut d'Imagerie Biomédicale, Neurospin, CEA Saclay, Gif-sur-Yvette, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Gras
authors.affiliation: Institute of Neuroscience and Medicine - 4, Medical Imaging Physics, Forschungszentrum Jülich GmbH, Jülich, Germany.
authors.forename: Ezequiel
authors.initials: E
authors.lastname: Farrher
authors.affiliation: Institute of Neuroscience and Medicine - 4, Medical Imaging Physics, Forschungszentrum Jülich GmbH, Jülich, Germany.|Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany.
authors.forename: Farida
authors.initials: F
authors.lastname: Grinberg
authors.affiliation: Institute of Neuroscience and Medicine - 4, Medical Imaging Physics, Forschungszentrum Jülich GmbH, Jülich, Germany.|Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany.
authors.forename: N Jon
authors.initials: NJ
authors.lastname: Shah
mesh_terms: D000465:Algorithms; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D010992:Plethysmography, Impedance / Q000379:methods*; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D011522:Protons
keywords: diffusion; dual-echo; mean diffusivity; proton density; quantitative imaging; relaxation time mapping; steady-state; steady-state free precession