title: Magnetization transfer from inhomogeneously broadened lines (ihMT): Experimental optimization of saturation parameters for human brain imaging at 1.5 Tesla.
abstract: OBJECTIVE
  Recently a new MR endogenous contrast mechanism was reported. It allows specifically imaging the magnetization transfer (MT) effect arising from inhomogeneously broadened components of the NMR spectrum, and was hence dubbed ihMT. Such unique NMR lineshape properties are presumably occurring in myelin because of its specifically ordered, multilayered sheath structure. Here, optimization of a pulsed ihMT preparation module is presented to provide guidance for future studies and improve the understanding of underlying contrast mechanisms.
  
  
  METHODS
  This study was performed at 1.5 Tesla on healthy volunteers. A pulsed ihMT preparation was implemented in combination with a HASTE readout module. The pulse width, interpulse repetition time, total saturation duration and RF saturation power were considered for optimization of the ihMT sensitivity and contrast.
  
  
  RESULTS
  An optimal configuration of the preparation module was derived, leading to 10% ihMT signal in internal capsule (relative to unsaturated data) and around 200% signal increase relative to gray matter, i.e., approximately 10-fold superior contrast compared with conventional MT ratios, measured under similar experimental conditions.
  
  
  CONCLUSIONS
  Overall the ihMT sequence was robust, sensitive and very specific for white matter. These findings suggest great potential for assessing brain myelination and for better characterization of myelin related disorders.
authors: Aix Marseille Université, CRMBM-CEMEREM UMR 7339, CNRS - AMU, Marseille, France.
authors: Olivier M
authors: OM
authors: Girard
authors: Aix Marseille Université, CRMBM-CEMEREM UMR 7339, CNRS - AMU, Marseille, France.
authors: Valentin H
authors: VH
authors: Prevost
authors: Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
authors: Gopal
authors: G
authors: Varma
authors: Aix Marseille Université, CRMBM-CEMEREM UMR 7339, CNRS - AMU, Marseille, France.
authors: Patrick J
authors: PJ
authors: Cozzone
authors: Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
authors: David C
authors: DC
authors: Alsop
authors: Aix Marseille Université, CRMBM-CEMEREM UMR 7339, CNRS - AMU, Marseille, France.
authors: Guillaume
authors: G
authors: Duhamel
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D064368:Healthy Volunteers; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012680:Sensitivity and Specificity; D066127:White Matter / Q000033:anatomy & histology*
keywords: ihMT; inhomogeneously broadened lines; magnetization transfer; myelin; specificity; white matter