title: Myelination process in preterm subjects with periventricular leucomalacia assessed by magnetization transfer ratio.
abstract: BACKGROUND
  Magnetization transfer imaging assesses the myelination status of the brain.
  
  
  OBJECTIVE
  To study the progress of myelination in children with periventricular leucomalacia (PVL) by measuring the magnetization transfer ratio (MTR) and to compare the MTR values with normal values.
  
  
  METHODS
  Brain MTR in 28 PVL subjects (16 males, 12 females, gestational age 30.7+/-2.5 weeks, corrected age 3.1+/-2.9 years) was measured using a 3D gradient echo sequence (TR/TE 32/8 ms, flip angle 60 degrees, 4 mm/2 mm overlapping sections) without and with magnetization transfer prepulse and compared with normal values for preterm subjects.
  
  
  RESULTS
  MTR of white-matter structures followed a monoexponential function model (y=A-B*exp(-x/C)) while the thalamus and caudate nucleus had a poor goodness of fit. MTR of the splenium of the corpus callosum reached a final value lower than normal (0.67 versus 0.70) at a younger age [t(99%) at 10.32 versus 18.90 months; P<0.05]. MTR of the normal-appearing occipital white matter and of the genu of the corpus callosum reached a normal final MTR but at a younger age than normal preterm infants [t(99%) at 8.51 versus 14.50 months and 12.51 versus 20.85 months, respectively].
  
  
  CONCLUSIONS
  In PVL subjects, myelination of the splenium is characterized by early arrest and deficient maturation. Accelerated myelination in unaffected white matter might suggest a compensatory process of reorganization.
authors.affiliation: Department of Radiology, Medical School, University of Ioannina, Ioannina, 45110, Greece.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Xydis
authors.forename: Loukas
authors.initials: L
authors.lastname: Astrakas
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Drougia
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Gassias
authors.forename: Styliani
authors.initials: S
authors.lastname: Andronikou
authors.forename: Maria
authors.initials: M
authors.lastname: Argyropoulou
mesh_terms: D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D005865:Gestational Age; D006801:Humans; D021621:Imaging, Three-Dimensional; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D007969:Leukomalacia, Periventricular / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012016:Reference Values; D012044:Regression Analysis; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media