Diffusion Tensor Imaging in Fixed Brain Tissue at 7.0 T

The purpose of this work is to assess the feasibility of performing quantitative in vitro brain tissue diffusion tensor imaging (DTI) measurements and to examine their comparability to in vivo measurements. DTI of fixed tissue at high field strength is potentially a very valuable investigative tool as very high spatial resolution can be achieved. DTI was applied to human and mouse brain fixed tissue samples as well as in vivo measurements of the mouse brain. T(1) and T(2) relaxography of the fixed tissue samples was also performed to provide further characterization of the tissue. All experiments were performed at 7 T. The fractional anisotropy (FA) of the human fixed brain tissue samples is found to be higher in the corpus callosum than in the occipital white matter region, consistent with in vivo measurements reported in the literature. Our FA measurements of the corpus callosum of a mouse brain are also found to be the same both in vitro and in vivo. This preliminary work supports the use of DTI in both fixed human and fixed animal brain tissue as a valid investigative tool. With the increased availability of brain banks in different brain disorders, DTI in fixed tissue may prove to be a very useful method for the study of white matter abnormalities.