title: The research of myelinization of normal fetal brain with magnetic resonance imaging.
abstract: OBJECTIVE
  To investigate the growth and development of myelin of sheath fetal brain.
  
  
  METHODS
  Forty-four cases of pregnant women were imaged with magnetic resonance (MR) at 0.35 T (tesla). The signal changes of the main structures of fetal brain were analysed.
  
  
  RESULTS
  The signal intensity of cerebral (except basal ganglia) and cerebellar matter was hypo-signal on the T1WI (T1 weighted spin-echo image), iso-signal of the PDWI (Proton density weighted image) and hyper-signal on the T2WI (T2 weighted spin-echo image). As to the brain stem and basal ganglia, their signal intensities showed difference in different gestational weeks on T1WI. The intensities were of slight hypo-signal before and iso-signal after the 29th week. However, their signal intensities on PDWI and T2WI were the same as those of the cerebral and cerebellar matter.
  
  
  CONCLUSIONS
  There was no myelinization of fetal cerebral (except basal ganglia) and cerebellar matter during pregnant period. The myelin sheath was formed in the brain stem and basal ganglia after 29 gestational weeks. The process of myelinization began from brain stem to basal ganglia.
mesh_terms: D000328:Adult; D001921:Brain / Q000196:embryology*; D005260:Female; D005333:Fetus; D005865:Gestational Age; D006801:Humans; D008279:Magnetic Resonance Imaging; D009186:Myelin Sheath / Q000502:physiology*; D011247:Pregnancy