title: Measuring longitudinal myelin water fraction in new multiple sclerosis lesions.
abstract: OBJECTIVE
  Investigating the potential of myelin repair strategies in multiple sclerosis (MS) requires an understanding of myelin dynamics during lesion evolution. The objective of this study is to longitudinally measure myelin water fraction (MWF), an MRI biomarker of myelin, in new MS lesions and to identify factors that influence their subsequent myelin content.
  
  
  METHODS
  Twenty-three MS patients were scanned with whole-brain Fast Acquisition with Spiral Trajectory and T2prep (FAST-T2) MWF mapping at baseline and median follow-up of 6 months. Eleven healthy controls (HC) confirmed the reproducibility of FAST-T2 in white matter regions of interests (ROIs) similar to a lesion size. A random-effect-model was implemented to determine the association between baseline clinical and lesion variables and the subsequent MWF.
  
  
  RESULTS
  ROI-based measurements in HCs were highly correlated between scans [mean r = 0.893 (.764-.967)]. In MS patients, 38 gadolinium enhancing (Gd+) and 25 new non-enhancing (Gd-) T2 hyperintense lesions (5.7 months, ±3.8) were identified. Significant improvement in MWF was seen in Gd+ lesions (0.035 ± 0.029, p < 0.001) as compared to Gd- lesions (0.006 ± 0.017, p = 0.065). In the model, a higher baseline MWF (p < 0.001) and the presence of Gd (p < 0.001) were associated with higher subsequent MWF.
  
  
  CONCLUSIONS
  FAST T2 provides a clinically feasible method to quantify MWF in new MS lesions. The observed influence of baseline MWF, which represents a combined effect of both resolving edema and myelin change within acute lesions, suggests that the extent of initial inflammation impacts final myelin recovery.
authors.affiliation: Department of Neurology, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Vargas
authors.affiliation: Department of Neurology, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Monohan
authors.affiliation: Department of Radiology, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Sneha
authors.initials: S
authors.lastname: Pandya
authors.affiliation: Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY, USA ; Department of Radiology, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Ashish
authors.initials: A
authors.lastname: Raj
authors.affiliation: Department of Neurology, Weill Cornell Medical College, New York, NY, USA ; Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Vartanian
authors.affiliation: Department of Radiology, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Thanh D
authors.initials: TD
authors.lastname: Nguyen
authors.affiliation: Department of Mathematics, Cleveland State University, Cleveland, OH.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Hurtado Rúa
authors.affiliation: Department of Neurology, Weill Cornell Medical College, New York, NY, USA ; Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY, USA.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Gauthier
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009103:Multiple Sclerosis / Q000473:pathology*; D009186:Myelin Sheath / Q000737:chemistry / Q000473:pathology*; D014867:Water / Q000032:analysis
chemical_list: D014867:Water
keywords: Acute lesion; MRI; Multiple sclerosis; Myelin; Myelin water fraction (MWF)