Comparing microstructural and macrostructural development of the cerebral cortex in premature newborns: diffusion tensor imaging versus cortical gyration.

This study assessed microstructural development in four regions of the human cerebral cortex during preterm maturation using diffusion tensor imaging (DTI), compared to the macrostructural development of cortical gyration evaluated using three-dimensional volumetric T1-weighted MR imaging. Thirty-seven premature infants of estimated gestational age (EGA) ranging from 25 to 38 weeks were prospectively enrolled and imaged in an MR-compatible neonatal incubator with a high-sensitivity neonatal head coil. Cortical gyration was measured quantitatively as the ratio of gyral height to width on the volumetric MR images in four regions bilaterally (superior frontal, superior occipital, precentral, and postcentral gyri). Mean diffusivity (D(av)), fractional anisotropy (FA-the fraction of D(av) that is anisotropic), and the three DTI eigenvalues (components of diffusivity radial and tangential to the pial surface of cortex) were measured in the same cortical regions. Cortical gyration scores, FA, and radial diffusivity were all significantly correlated with EGA (P < 0.0001). However, in multivariate analysis, no significant relationship (P > 0.05) was found between DTI parameters and cortical gyration beyond their common association with estimated gestational age. Pre- and postcentral gyri had significantly lower anisotropy than the superior occipital and superior frontal gyri (P < 0.05), indicating that DTI is sensitive to regional heterogeneity in cortical development. Maturational changes in the DTI eigenvalues of cortical gray matter were found to differ from those that have previously been described in developing white matter, with a significant age-related decline in the radial diffusivity (P < 0.0001) but not in the tangential diffusivities (P > 0.05).

Early laminar organization of the human cerebrum demonstrated with diffusion tensor imaging in extremely premature infants.

Diffusion tensor imaging (DTI) was used to delineate early laminar organization of the cerebrum in two extremely premature infants imaged postnatally at estimated ages of 25 and 27 menstrual weeks. The diffusivity and anisotropy of the cortical plate, subplate zone, intermediate zone, subventricular and periventricular zones, and germinal matrix are examined. Automated segmentation of diffusion tensor images to reveal the laminar architecture of the developing human cerebrum is also demonstrated.