title: Quantitative MRI in hypomyelinating disorders: Correlation with motor handicap.
abstract: OBJECTIVE
  To assess the correlation of tissue parameters estimated by quantitative magnetic resonance (MR) techniques and motor handicap in patients with hypomyelination.
  
  
  METHODS
  Twenty-eight patients with different causes of hypomyelination (12 males, 16 females; mean age 10 years) and 61 controls (33 males, 28 females; mean age 8 years) were prospectively investigated. We quantified T2 relaxation time, magnetization transfer ratio, fractional anisotropy, mean, axial, and radial diffusivities, and brain metabolites. We performed measurements in the splenium, parietal deep white matter, and corticospinal tracts in the centrum semiovale. We further analyzed diffusion measures using tract-based spatial statistics. We estimated severity of motor handicap by the gross motor function classification system. We evaluated correlation of handicap with MR measures by linear regression analyses.
  
  
  RESULTS
  Fractional anisotropy, magnetization transfer ratio, choline, and N-acetylaspartate/creatine ratio were lower and diffusivities, T2 values, and inositol were higher in patients than in controls. Tract-based spatial statistics showed that these changes were widespread for fractional anisotropy (96% of the white matter skeleton), radial (93%) and mean (84%) diffusivity, and less so for axial diffusivity (20%). Correlation with handicap yielded radial diffusivity and N-acetylaspartate/creatine ratio as strongest independent explanatory variables.
  
  
  CONCLUSIONS
  Gross motor function classification system grades are in part explained by MR measures. They indicate that mainly lack of myelin and, to a lesser degree, loss of axonal integrity codetermine the degree of motor handicap in patients with hypomyelinating disorders. These MR measures can be used to evaluate strategies that are aimed at promotion of myelination.
authors.affiliation: From the Department of Child Neurology (M.E.S., N.I.W., M.S.v.d.K.), VU University Medical Center, and Neuroscience Campus Amsterdam; Department of Clinical Epidemiology and Biostatistics (W.N.v.W.), VU University Medical Center; Department of Mathematics (W.N.v.W.), and Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (M.S.v.d.K., P.J.W.P.), VU University, Amsterdam; and Departments of Radiology (F.B.) and Physics and Medical Technology (P.J.W.P.), VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Marjan E
authors.initials: ME
authors.lastname: Steenweg
authors.affiliation: From the Department of Child Neurology (M.E.S., N.I.W., M.S.v.d.K.), VU University Medical Center, and Neuroscience Campus Amsterdam; Department of Clinical Epidemiology and Biostatistics (W.N.v.W.), VU University Medical Center; Department of Mathematics (W.N.v.W.), and Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (M.S.v.d.K., P.J.W.P.), VU University, Amsterdam; and Departments of Radiology (F.B.) and Physics and Medical Technology (P.J.W.P.), VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Nicole I
authors.initials: NI
authors.lastname: Wolf
authors.affiliation: From the Department of Child Neurology (M.E.S., N.I.W., M.S.v.d.K.), VU University Medical Center, and Neuroscience Campus Amsterdam; Department of Clinical Epidemiology and Biostatistics (W.N.v.W.), VU University Medical Center; Department of Mathematics (W.N.v.W.), and Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (M.S.v.d.K., P.J.W.P.), VU University, Amsterdam; and Departments of Radiology (F.B.) and Physics and Medical Technology (P.J.W.P.), VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Wessel N
authors.initials: WN
authors.lastname: van Wieringen
authors.affiliation: From the Department of Child Neurology (M.E.S., N.I.W., M.S.v.d.K.), VU University Medical Center, and Neuroscience Campus Amsterdam; Department of Clinical Epidemiology and Biostatistics (W.N.v.W.), VU University Medical Center; Department of Mathematics (W.N.v.W.), and Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (M.S.v.d.K., P.J.W.P.), VU University, Amsterdam; and Departments of Radiology (F.B.) and Physics and Medical Technology (P.J.W.P.), VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Frederik
authors.initials: F
authors.lastname: Barkhof
authors.affiliation: From the Department of Child Neurology (M.E.S., N.I.W., M.S.v.d.K.), VU University Medical Center, and Neuroscience Campus Amsterdam; Department of Clinical Epidemiology and Biostatistics (W.N.v.W.), VU University Medical Center; Department of Mathematics (W.N.v.W.), and Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (M.S.v.d.K., P.J.W.P.), VU University, Amsterdam; and Departments of Radiology (F.B.) and Physics and Medical Technology (P.J.W.P.), VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Marjo S
authors.initials: MS
authors.lastname: van der Knaap
authors.affiliation: From the Department of Child Neurology (M.E.S., N.I.W., M.S.v.d.K.), VU University Medical Center, and Neuroscience Campus Amsterdam; Department of Clinical Epidemiology and Biostatistics (W.N.v.W.), VU University Medical Center; Department of Mathematics (W.N.v.W.), and Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (M.S.v.d.K., P.J.W.P.), VU University, Amsterdam; and Departments of Radiology (F.B.) and Physics and Medical Technology (P.J.W.P.), VU University Medical Center, Amsterdam, the Netherlands. pjw.pouwels@vumc.nl.
authors.forename: Petra J W
authors.initials: PJ
authors.lastname: Pouwels
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003337:Corpus Callosum / Q000000981:diagnostic imaging*; D003711:Demyelinating Diseases / Q000000981:diagnostic imaging*; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011712:Pyramidal Tracts / Q000000981:diagnostic imaging*; D012720:Severity of Illness Index; D066127:White Matter / Q000000981:diagnostic imaging*; D055815:Young Adult