![qspace credit report qspace credit report](https://blog.checkpoint.com/wp-content/uploads/2021/01/q4-5.png)
![qspace credit report qspace credit report](http://s3.amazonaws.com/finovate-archive/old/WindowsLiveWriter/CreditKarm.comLaunchFreeCreditScoreTools_10A35/image_thumb_3.png)
#QSPACE CREDIT REPORT FULL#
The full Reynolds stress tensor is obtained from a voxel-wise three-dimensional Gaussian fit using the magnitude data of all acquisitions. The velocity encoding scheme is based on the ICOSA6 method with six icosahedral encoding directions and multiple encoding values are measured to increase the dynamic range.
![qspace credit report qspace credit report](http://s3.amazonaws.com/finovate-archive/old/WindowsLiveWriter/CreditKarm.comLaunchFreeCreditScoreTools_10A35/image_thumb_5.png)
This study presents magnetic resonance velocimetry (MRV) Reynolds Stress measurements in a periodic hill channel with a hill Reynolds number of Re = 29,500. The variance in T 1 val- ues appeared to be negligible in healthy white matter except in regions containing partial volumes of gray matter. In vivo, diffusion time dependence of the axial and radial diffusivity was detected. Ex- periments with a two-compartment phantom consisting of distilled water and paraffinum perliquidum demonstrated the ability of twice-refocused stimulated echoes to differentiate between time-dependent diffusion and compartmental T 1 relaxation. In order to study long diffusion times between 50 and 500ms without affecting T 1 weight- ing, a pulse sequence featuring twice-refocused stimulated echoes was implemented. Approximately matching the frequency power spectrum of linear and spherical b-tensor encoding resulted in up to 50% lower anisotropic variance values, which indicates a strong bias in multidimensional b-tensor encoding depending on the frequency content of the applied diffusion gradients. At shorter effective diffusion times, stronger signal attenuation and higher mean diffusivity estimates were measured. Experiments with oscillating diffusion gradients revealed the presence of diffusion time dependence in the brain for frequencies in the range of 0 to 30Hz. Based on biophysical models for water diffusion in the brain, these results are well explained by a shift in compartmental weighting between intra- and extra-axonal water. This effect was attributed to weaker signal attenuation with linear b-tensor encoding at 7T, whereas the signal attenuation with spherical b-tensor encoding was unaffected by a change in field strength. Higher diffusion anisotropy was measured at 7T compared to 3T. Furthermore, the field strength dependence of the microscopic diffusion anisotropy was investigated. This finding is probably related to the second-order approximation of the signal attenuation in q-space trajectory imaging. In discrepancy to the established theory, the simulation also showed that all investigated microscopic anisotropy parameters were affected by the orientation coherence of the diffusion tensor distribution. The simulation results indicate that the microscopic lattice index and the microscopic scaled relative anisotropy provide consistently high contrast-to-noise ratios. A selection of parameters to quantify microscopic diffusion anisotropy were compared in terms of contrast-to-noise ratio in simulations with three characteristic diffusion tensor distributions. These methods were employed to study water diffusion in the human brain. The subject of this thesis was the development of pulse sequences and optimization schemes for mul- tidimensional diffusion encoding. Diffusion-weighted magnetic resonance imaging with multidimensional diffusion encoding provides novel image contrasts to non-invasively study tissue microstructure.