title: Quantitative MRI in the very preterm brain: assessing tissue organization and myelination using magnetization transfer, diffusion tensor and T₁ imaging.
abstract: Magnetization transfer ratio (MTR), diffusion tensor imaging (DTI) parameters and T(1) relaxometry values were used to create parametric maps characterizing the tissue microstructure of the neonatal brain in infants born very premature (24-32 gestational weeks) and scanned at preterm and term equivalent age. Group-wise image registration was used to determine anatomical correspondence between individual scans and the pooled parametric data at the preterm and term ages. These parametric maps showed distinct contrasts whose interrelations varied across brain regions and between the preterm and term period. Discrete patterns of regional variation were observed for the different quantitative parameters, providing evidence that MRI is sensitive to multiple independent aspects of brain maturation. MTR values showed a marked change in the pattern of regional variation at term equivalent age compared to the preterm period such that the ordinal ranking of regions by signal contrast changed. This was unlike all other parameters where the regional ranking was preserved at the two time points. Interpreting the data in terms of myelination and structural organization, we report on the concordance with available histological data and demonstrate the value of quantitative MRI for tracking brain maturation over the neonatal period.
authors.affiliation: Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8. rmanor@phenogenomics.ca
authors.forename: Revital
authors.initials: R
authors.lastname: Nossin-Manor
authors.forename: Dallas
authors.initials: D
authors.lastname: Card
authors.forename: Drew
authors.initials: D
authors.lastname: Morris
authors.forename: Salma
authors.initials: S
authors.lastname: Noormohamed
authors.forename: Manohar M
authors.initials: MM
authors.lastname: Shroff
authors.forename: Hilary E
authors.initials: HE
authors.lastname: Whyte
authors.forename: Margot J
authors.initials: MJ
authors.lastname: Taylor
authors.forename: John G
authors.initials: JG
authors.lastname: Sled
mesh_terms: D000375:Aging / Q000473:pathology*; D001921:Brain / Q000166:cytology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure*