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 coefficient (D̄) and quantitative diffusion anisotropy (A(σ)) 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 D̄ and A(σ) were measured of interest chosen in the cortical gray matter, centrum semiovale, caudate nuclei, lentiform nuclei, thalami, internal capsules, and cerebellar hemispheres. RESULTS: The D̄ 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 D̄, with D̄ decreasing as gestational age increases. The A(σ) values in the white matter in newborns are lower than those in adults. Values of A(σ) show statistically significant correlations with gestational age only in the white matter of the centrum semiovale, in which A(σ) value increase sharply near term. CONCLUSION: The D̄ values primarily reflect overall brain water content. The A(σ) values are more sensitive to tissue microstructure (eg, white matter packing and myelination). The D̄ and A(σ) images reveal information not apparent on T1- and T2-weighted images.