USE OF AN ENHANCED GRADIENT SYSTEM FOR DIFFUSION MR-IMAGING WITH MOTION-ARTIFACT REDUCTION

Purpose. A spin-echo diffusion-sensitized pulse sequence using high gr adients (23 mT/m) is introduced. Material and Methods. In order to min imize motion artefacts, velocity-compensating gradients, EGG-triggerin g and post-processing with phase correction and raw data averaging usi ng navigator echoes was performed. The in vitro ratio of diffusion coe fficients for water and acetone was determined and the water self-diff usion coefficient at different temperatures was evaluated. The pulse s equence was tested in 7 healthy volunteers and in 2 tumour patients wi th astrocytomas of grades I-II and III-IV. Both single-slice and multi -slice techniques were used. Results. The incorporation of phase corre ction clearly improved the quality of both diffusion-encoded images an d the calculated diffusion maps. Mean values of the diffusion coeffici ents in vivo were for CSF 2.66x10(-9) m(2)/s and for white and grey ma tter 0.69x10(-9) m(2)/s and 0.87x10(-9) m(2)/s, respectively.Conclusio n: Velocity-compensating gradients in combination with a high gradient strength were shown to be useful for in vive diffusion MR imaging.