Estimation of Intravoxel Fiber-Orientation Distribution via Non-Convex Regularized Spherical Deconvolution

2019 ◽  
Vol 56 (20) ◽  
pp. 201007
Author(s):  
楚春雨 Chu Chunyu ◽  
刘春梅 Liu Chunmei
Keyword(s):  
Fiber Orientation ◽  
Orientation Distribution ◽  
Spherical Deconvolution ◽  
Fiber Orientation Distribution

scholarly journals Effects of Inaccurate Response Function Calibration on Characteristics of the Fiber Orientation Distribution in Diffusion MRI

2019 ◽  
Author(s):  
Fenghua Guo ◽  
Chantal M.W. Tax ◽  
Alberto De Luca ◽  
Max A. Viergever ◽  
Anneriet Heemskerk ◽  
...  
Keyword(s):  
Response Function ◽  
Fiber Orientation ◽  
Shape Factor ◽  
Diffusion Mri ◽  
Orientation Distribution ◽  
Fiber Tracking ◽  
Fiber Tractography ◽  
Scaling Factors ◽  
Spherical Deconvolution ◽  
Fiber Orientation Distribution

AbstractDiffusion MRI of the brain enables to quantify white matter fiber orientations noninvasively. Several approaches have been proposed to estimate such characteristics from diffusion MRI data with spherical deconvolution being one of the most widely used methods. Constrained spherical deconvolution requires to define – or derive from the data – a response function, which is used to compute the fiber orientation distribution (FOD). This definition or derivation is not unequivocal and can thus result in different characteristics of the response function which are expected to affect the FOD computation and the subsequent fiber tracking. In this work, we explored the effects of inaccuracies in the shape and scaling factors of the response function on the FOD characteristics. With simulations, we show that underestimation of the shape factor in the response functions has a larger effect on the FOD peaks than overestimation of the shape factor, whereas the latter will cause more spurious peaks. Moreover, crossing fiber populations with a smaller separation angle were more sensitive to the response function inaccuracy than fiber populations with more orthogonal separation angles. Furthermore, the FOD characteristics show deviations as a result of modified shape and scaling factors of the response function. Results with the in vivo data demonstrate that the deviations of the FODs and spurious peaks can further deviate the termination of propagation in fiber tracking. This work highlights the importance of proper definition of the response function and how specific calibration factors can affect the FOD and fiber tractography results.

Effect of Fiber Orientation on the Tensile Strength in Fiber-Reinforced Polymeric Composite Materials

2005 ◽  
Vol 297-300 ◽  
pp. 2897-2902 ◽  
Author(s):  
Jin Woo Kim ◽  
Jung Ju Lee ◽  
Dong Gi Lee
Keyword(s):  
Tensile Strength ◽  
Composite Material ◽  
Fiber Orientation ◽  
Polymeric Composite ◽  
Orientation Distribution ◽  
Fiber Content ◽  
Fiber Reinforced ◽  
Composite Sheet ◽  
Content Ratio ◽  
Fiber Orientation Distribution

The study for strength calculation of one way fiber-reinforced composites and the study measuring precisely fiber orientation distribution were presented. However, because the DB that can predict mechanical properties of composite material and fiber orientation distribution by the fiber content ratio was not constructed, we need the systematic study for that. Therefore, in this study, we investigated what effect the fiber content ratio and fiber orientation distribution have on the strength of composite sheet after making fiber reinforced polymeric composite sheet by changing fiber orientation distribution with the fiber content ratio. The result of this study will become a guide to design data of the most suitable parts design or fiber reinforced polymeric composite sheet that uses the fiber reinforced polymeric composite sheet in industry spot, because it was conducted in terms of developing products. We studied the effect the fiber orientation distribution has on tensile strength of fiber reinforced polymeric composite material and achieved this results below. We can say that the increasing range of the value of fiber reinforced polymeric composite’s tensile strength in the direction of fiber orientation is getting wider as the fiber content ratio increases. It shows that the value of fiber reinforced polymeric composite’s tensile strength in the direction of fiber orientation 90° is similar with the value of polypropylene’s intensity when fiber orientation function is J= 0.7, regardless of the fiber content ratio. Tensile strength of fiber reinforced polymeric composite is affected by the fiber orientation distribution more than by the fiber content ratio.

scholarly journals Evaluating the performance of 3-tissue constrained spherical deconvolution pipelines for within-tumor tractography

2019 ◽  
Author(s):  
Hannelore Aerts ◽  
Thijs Dhollander ◽  
Daniele Marinazzo
Keyword(s):  
White Matter ◽  
Tumor Tissue ◽  
Diffusion Tensor ◽  
Orientation Distribution ◽  
Constrained Spherical Deconvolution ◽  
Spherical Deconvolution ◽  
Fiber Orientation Distribution ◽  
Tissue Compartments ◽  
Diffusion Tensor Imaging Dti ◽  
Single Shell

AbstractThe use of diffusion MRI (dMRI) for assisting in the planning of neurosurgery has become increasingly common practice, allowing to non-invasively map white matter pathways via tractography techniques. Limitations of earlier pipelines based on the diffusion tensor imaging (DTI) model have since been revealed and improvements were made possible by constrained spherical deconvolution (CSD) pipelines. CSD allows to resolve a full white matter (WM) fiber orientation distribution (FOD), which can describe so-called “crossing fibers”: complex local geometries of WM tracts, which DTI fails to model. This was found to have a profound impact on tractography results, with substantial implications for presurgical decision making and planning. More recently, CSD itself has been extended to allow for modeling of other tissue compartments in addition to the WM FOD, typically resulting in a 3-tissue CSD model. It seems likely this may improve the capability to resolve WM FODs in the presence of infiltrating tumor tissue. In this work, we evaluated the performance of 3-tissue CSD pipelines, with a focus on within-tumor tractography. We found that a technique named single-shell 3-tissue CSD (SS3T-CSD) successfully allowed tractography within infiltrating gliomas, without increasing existing single-shell dMRI acquisition requirements.

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