260 Neonatal Diffusion Tensor Imaging of the Brain at 3 Tesla

In magnetic resonance imaging (MRI) the trend is to move towards higher magnetic field strengths. This tendency is driven by the possibility to obtain better signal to noise ratios. One recent development is diffusion tensor imaging (DTI). As water diffusion is less hindered along the length of the axon than its cross section DTI allows for the investigation of the white matter microstructure. For example such histological correlates as the size cross sectional density, organization of axons and degree of myelination can be studied with this method. 13 preterm infants at term equivalent age and 6 healthy term newborn controls were studied. Median GA in the preterm group was 31 weeks, median postmenstrual age (PMA) = 41 weeks when MR was performed. Term controls were examined at a median postnatal age of 2 days. Each subject underwent a single MRI examination on a 3 Tesla Trio Siemens scanner. MR protocol included a DTI sequence with 6 non-collinear diffusion weighting directions. From the raw data a diffusion tensor was estimated with linear least square fitting and from the tensor a scalar measure of anisotropic diffusion was calculated. This measure, called fractional anisotropy (FA), has been used to compare the groups. We present results demonstrating the feasibility of DTI at 3 Tesla in neonatal subjects. We found Anisotropy values which were not significantly different between preterm infants at term-equivalent age and healthy term controls in Corpus callosum splenium and White matter. However, values in the posterior limb of internal capsule (PLIC) were significantly higher for the preterm group (p= 0.0017).