Cerebral maturation in the early preterm period-A magnetization transfer and diffusion tensor imaging study using voxel-based analysis.
The magnetization transfer ratio (MTR) and diffusion tensor imaging (DTI) correlates of early brain development were examined in cohort of 18 very preterm neonates (27-31 gestational weeks) presenting with normal radiological findings scanned within 2weeks after birth (28-32 gestational weeks). A combination of non-linear image registration, tissue segmentation, and voxel-wise regression was used to map the age dependent changes in MTR and DTI-derived parameters in 3D across the brain based on the cross-sectional in vivo preterm data. The regression coefficient maps obtained differed between brain regions and between the different quantitative MRI indices. Significant linear increases as well as decreases in MTR and DTI-derived parameters were observed throughout the preterm brain. In particular, the lamination pattern in the cerebral wall was evident on parametric and regression coefficient maps. The frontal white matter area (subplate and intermediate zone) demonstrated a linear decrease in MTR. While the intermediate zone showed an unexpected decrease in fractional anisotropy (FA) with age, with this decrease (and the increase in mean diffusivity (MD)) driven primarily by an increase in radial diffusivity (RD) values, the subplate showed no change in FA (and an increase in MD). The latter was the result of a concomitant similar increase in axial diffusivity (AD) and RD values. Interpreting the in vivo results in terms of available histological data, we present a biophysical model that describes the relation between various microstructural changes measured by complementary quantitative methods available on clinical scanners and a range of maturational processes in brain tissue.
Diagnostic Imaging, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Neurosciences and Mental Health, Research Institute, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada. Electronic address: rmanor@mouseimaging.ca.
Revital
R
Nossin-Manor
Diagnostic Imaging, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.
Dallas
D
Card
Diagnostic Imaging, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Medical Imaging, University of Toronto, Toronto, ON M5S 3E2, Canada.
Charles
C
Raybaud
Diagnostic Imaging, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Neurosciences and Mental Health, Research Institute, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Medical Imaging, University of Toronto, Toronto, ON M5S 3E2, Canada.
Margot J
MJ
Taylor
Physiology and Experimental Medicine, Research Institute, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Medical Biophysics, University of Toronto, Toronto, ON M5G 2M9, Canada.
John G
JG
Sled
D016880:Anisotropy; D001921:Brain / Q000196:embryology* / Q000254:growth & development; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D005865:Gestational Age; D066128:Gray Matter / Q000033:anatomy & histology / Q000254:growth & development; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009186:Myelin Sheath / Q000502:physiology; D009412:Nerve Fibers; D066127:White Matter / Q000033:anatomy & histology / Q000254:growth & development
Brain maturation; DTI; MTR; Preterm neonates; Quantitative MRI; Voxel based analysis