MR microscopy of water diffusion tensor in biological systems

Diffusion tensor imaging (DTI) of the control and mechanically injured spin al cord of a rat in vitro and in vivo are reported. In vitro experiments we re done on a home-built 6.4 T magnetic resonance microscope. Results for fo rmaline-fixed samples show significant differences in diffusion tensor comp onents between gray matter and white matter of the control spinal cord. Mor eover, it is shown that aleady 6-10 min after the injury DTI can detect cha nges in water diffusion in areas extending far beyond the region of primary tissue damage. In vivo experiments were performed using a 9.4 T Magnex mag net and Bruker Medspec imaging system. Good-quality DTI images, free from m otion artifacts were obtained. Results from control samples confirm differe nces in water diffusion between white matter and gray matter, observed ill vitro. In vivo experiments show that characteristic changes in water diffus ion observed in vitro 6-10 min after injury are preserved 60-360 min after injury, without significant alteration during this time.