Final Activity Report Summary - NEUROWATERDIF (Mapping of Multicompartmental Anisotropic Water Diffusion in Nervous Tissue) Spinal cord injuries as well as neurodegenerative diseases are caused by abrupt or progressing damage in axons or myelin tissue. They often lead to temporary or permanent disability and thus high cost of health care and loss of socio-economic activity of the disabled patients. It is estimated that every year about 10,000 individuals across EU is paralysed due to spinal cord injury. Most often they are relatively young, with almost normal life expectancy after injury, which means high cost of healthcare. On the other hand, neurodegenerative diseases disable typically mature peoples, forcing them out of normal socio-economical activity and also adding high cost to health-care systems. MR imaging is one of the few methods allowing for non-invasive visualization of the biological structures with appropriate resolution. Possibility to choose different contrast parameters: proton density, spin-spin relaxation (T2), spin-lattice relaxation (T1), diffusion coefficient (tensor), flow or magnetisation transfer, allow for investigation of different aspects of molecular dynamics in biological systems. The present project was aimed in the elaboration of the physical and technological basis of the Diffusion Weighted MRI, as a tool for diagnostic methodology applicable to neurological trauma or disorder. The white matter in nervous tissue mainly consists of long axons, typically a few microns diameter, surrounded by semi-permeable myelin sheath, which is a barrier for water diffusion. Due to presence of the barrier diffusion is highly restricted in direction perpendicular to the axons axes and relatively free along them. Thus, for complete characterisation of the water diffusion in nervous tissue measurements of all diffusion tensor components is required. In addition, intracellular, myelin and extra-cellular water pools has different mobility and in consequence the measured MR signal contains components corresponding to water pools with different relaxation times and diffusion coefficients. After completion of the project we were able to assess correspondence between the microscopic parameters of the axons geometry and parameters of the measured diffusion weighted MR signal of the normal and injured spinal cord. On the basis of this data optimized protocols for diffusion weighted MRI on animal model of the injured spinal cord were elaborated and used during another projects aimed in assessment of the effects of neuroprotective drugs on spinal cord traumatic injury.