title: Axial and radial diffusivity in preterm infants who have diffuse white matter changes on magnetic resonance imaging at term-equivalent age.
abstract: OBJECTIVE
  Diffuse excessive high signal intensity (DEHSI) is observed in the majority of preterm infants at term-equivalent age on conventional MRI, and diffusion-weighted imaging has shown that apparent diffusion coefficient values are elevated in the white matter (WM) in DEHSI. Our aim was to obtain diffusion tensor imaging on preterm infants at term-equivalent age and term control infants to test the hypothesis that radial diffusivity was significantly different in the WM in preterm infants with DEHSI compared with both preterm infants with normal-appearing WM on conventional MRI and term control infants.
  
  
  METHODS
  Diffusion tensor imaging was obtained on 38 preterm infants at term-equivalent age and 8 term control infants. Values for axial (lambda1) and radial [(lambda2 + lambda3)/2] diffusivity were calculated in regions of interest positioned in the central WM at the level of the centrum semiovale, frontal WM, posterior periventricular WM, occipital WM, anterior and posterior portions of the posterior limb of the internal capsule, and the genu and splenium of the corpus callosum.
  
  
  RESULTS
  Radial diffusivity was elevated significantly in the posterior portion of the posterior limb of the internal capsule and the splenium of the corpus callosum, and both axial and radial diffusivity were elevated significantly in the WM at the level of the centrum semiovale, the frontal WM, the periventricular WM, and the occipital WM in preterm infants with DEHSI compared with preterm infants with normal-appearing WM and term control infants. There was no significant difference between term control infants and preterm infants with normal-appearing WM in any region studied.
  
  
  CONCLUSIONS
  These findings suggest that DEHSI represents an oligodendrocyte and/or axonal abnormality that is widespread throughout the cerebral WM.
authors.affiliation: Imaging Sciences Department, MRC Clinical Sciences Centre, London, United Kingdom.
authors.forename: Serena J
authors.initials: SJ
authors.lastname: Counsell
authors.forename: Yuji
authors.initials: Y
authors.lastname: Shen
authors.forename: James P
authors.initials: JP
authors.lastname: Boardman
authors.forename: David J
authors.initials: DJ
authors.lastname: Larkman
authors.forename: Olga
authors.initials: O
authors.lastname: Kapellou
authors.forename: Philip
authors.initials: P
authors.lastname: Ward
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Allsop
authors.forename: Frances M
authors.initials: FM
authors.lastname: Cowan
authors.forename: Joseph V
authors.initials: JV
authors.lastname: Hajnal
authors.forename: A David
authors.initials: AD
authors.lastname: Edwards
authors.forename: Mary A
authors.initials: MA
authors.lastname: Rutherford
mesh_terms: D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005865:Gestational Age; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007231:Infant, Newborn; D007234:Infant, Premature; D008279:Magnetic Resonance Imaging; D008297:Male; D047929:Term Birth