Normal brain in human newborns: Apparent diffusion coefficient and diffusion anisotropy measured by using diffusion tensor MR imaging

PURPOSE: To establish quantitative standards for the directionally averaged water apparent diffusion coefficient (D) and quantitative diffusion anisotrophy (A(sigma)) of normal brains in newborns by using diffusion tensor magnetic resonance (MR) imaging. MATERIALS AND METHODS: Diffusion tensor MR imaging was performed during the first 36 hours of life in 22 newborns (gestational age range, 31-41 weeks). Values of D and A(sigma), were measured in regions of interest chosen in the cortical gray matter, centrum semiovale, caudate nuclei, lentiform nuclei, thalami, internal capsules, and cerebellar hemispheres. RESULTS: The D values in the gray and white matter in newborns are considerably higher than those in adults. There is a striking correlation between gestational age and D, with D decreasing as gestational age increases. The A(sigma) values in the white mater in newborns are lower than those in adults. Values of A(sigma) show statistically significant correlations with gestational age only in the white mater of the centrum semiovale, in which A(sigma) values increase sharply near term. CONCLUSIONS: The D values primarily reflect overall brain water content. The A(sigma) values are more sensitive to tissue microstructure (eg, white matter packing and myelination). The D and A(sigma) images reveal information not apparent on T1- and T2-weighted images.