Research On Reconstruction Methods Of Complex White Matter Neural Fiber Structure

Focused on the reconstruction of complex white matter nerve fibers this paperquantitatively compared various fourth-order tensor imaging methods based onhigher-order tensor diffusion imaging and introduced new water diffusion model formulti-fiber crossing. The main contents are shown as follows:Regarding noise simulation this study determined the quantitative relationshipbetween the Rician noise and signal-to-noise ratio (SNR). Combining with therecommended standard of SNR of magnetic resonance image (MRI) the simulatingnoise to be applied was limited to a practical range, which is more consistent to theactual condition. This method enables the simulation conditions more realistic,making simulation results more practical, and provides a reference for the simulationexperiment of diffusion-weighted signal. Comprehensive and quantitative comparisonwas made between the imaging results of the positive and non-positive definitefourth-order tensor imaging. Taking stability and accuracy of the reconstructionmethod as evaluation criteria a quantitative research for the effects of the noise andthe number of diffusion weighted gradient directions was made. The ability to detectIVOH of the two methods was also evaluated in the regions of single fiber andmulti-fiber. The study results can provide advice in the choice of white matter fiberreconstruction methods.Using the4th order tensor decomposition method, the fiber reconstruction of theDWI in humen brain has been made and its ability to show fiber crossing in differentregions was also studied. In order to further study the effect of positive definite thepositive property was applied to this imaging method, then the reconstruction effect ofthe positive and non-positive method was compared.For DWI signal simulation the Monte Carlo method was introduced to solve thesimulation with multi-fiber, non-equal volume effect. Besides that this method candetermine the quantitative relationship between signal attenuation and fiber size,which is expected to achieve the selectivity study of a particular size range of whitematter fiber.