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You searched for subject:(b value optimization). Showing records 1 – 2 of 2 total matches.

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1. Gupta, Aman. Ultra-High Field MR Diffusion Tensor Imaging Characterization of Rabbit Tendons and Ligaments.

Degree: 2012, University of Illinois – Chicago

Tendons and ligaments are dense, fibrous connective tissues that facilitate transmission of loads from muscle to bone (tendon) or from bone to bone (ligament). These tissues are subjected to wear and tear from day-to-day mechanical usage leading to sprains, tendinopathies, or ruptures, each of which is a major source of musculoskeletal disability. Clinically, the diagnosis of tendon and ligament injury is based on a clinical examination as well as magnetic resonance imaging (MRI) of the relevant tissues. MRI is a reliable, non-invasive tool for detecting large and complete tears; however, conventional T1 and T2-weighted grayscale images exhibit poor contrast and a low signal-to-noise ratio which makes identification of low-grade injuries more challenging to delineate. Therefore, there exists a need for reliable, quantitative and more robust imaging approaches to assess tendon and ligament microstructure and integrity. One of these MR approaches is diffusion tensor imaging (DTI), an advanced MRI technique primarily used in neuroimaging applications. DTI assesses tissue microstructural organization by quantifying the 3D diffusion of water molecules within tissues. It relies on the basic diffusion principle that water molecules diffuse more readily along (i.e., parallel to), rather than across physical barriers (e.g., collagen fibers). Diffusion of water molecules can be quantified by the diffusion tensor in each voxel, whereby the magnitude and orientation of water diffusion can be computed throughout the tissue, thus revealing the fiber microstructure. The primary aims of the proposed studies are to demonstrate applicability and reliability of the DTI technique for tendons and ligaments, and determine the sensitivity of b-values to DTI derived parameters of tissue integrity. This is the first study to show feasibility and applicability of DTI on Tendons and Ligaments at ultra-high magnetic fields with high resolutions and measure DTI metrics from both tissue types. High Fractional Anisotropy values of 0.67 for semitendinosus tendons and 0.66 for medial collateral ligaments shows the highly anisotropic nature of these soft connective tissues.Axial diffusivity is about 3 times the radial diffusivity which shows diffusion directional anisotropy indicating diffusion preference along the fibers then across them. The present study showed fiber tractography of these tissues at ultra-high magnetic fields with a histological correlation confirming the highly-organized parallel collagen fiber microstructure. Diffusion tensor imaging is sensitive to the diffusional anisotropy differences and can show microstructural differences between tendons and ligaments through DTI metrics at 11. 7 T field strength. The current work also found the most feasible range of b-values of 300-600 s/mm2 which will be best suited for these tissue types at the given magnetic field strength of 11.7T and get more reliable DTI measurements. DTI metrics can provide insight into 3D tissue integrity and … Advisors/Committee Members: Magin, Richard L. (advisor), Wang, Vincent M. (committee member), Stebbins, Glenn T. (committee member), Royston, Thomas J. (committee member), Akpa, Belinda S. (committee member), Zelazny, Anthony M. (committee member).

Subjects/Keywords: Diffusion Tensor Imaging; Tendon; Ligament; Magnetic Resonance Imaging; ultra-high field; Fractional Anisotropy; Mean Diffusivity; Tractography; b-value optimization

…Specific Aim 3: Optimization aim To determine sensitivity of b-value on diffusion tensor metrics… …generated using DTIstudio for two semitendinosus tendons for a b-value of 200. The fiber tracts… …are shortened and less dense at this b-value indicating limited sensitivity of low b-value… …using DTIstudio for two semitendinosus tendons for a b-value of 500. The fiber tracts are long… …and denser at this b-value… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Gupta, A. (2012). Ultra-High Field MR Diffusion Tensor Imaging Characterization of Rabbit Tendons and Ligaments. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/9137

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Gupta, Aman. “Ultra-High Field MR Diffusion Tensor Imaging Characterization of Rabbit Tendons and Ligaments.” 2012. Thesis, University of Illinois – Chicago. Accessed December 04, 2020. http://hdl.handle.net/10027/9137.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Gupta, Aman. “Ultra-High Field MR Diffusion Tensor Imaging Characterization of Rabbit Tendons and Ligaments.” 2012. Web. 04 Dec 2020.

Vancouver:

Gupta A. Ultra-High Field MR Diffusion Tensor Imaging Characterization of Rabbit Tendons and Ligaments. [Internet] [Thesis]. University of Illinois – Chicago; 2012. [cited 2020 Dec 04]. Available from: http://hdl.handle.net/10027/9137.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Gupta A. Ultra-High Field MR Diffusion Tensor Imaging Characterization of Rabbit Tendons and Ligaments. [Thesis]. University of Illinois – Chicago; 2012. Available from: http://hdl.handle.net/10027/9137

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Cincinnati

2. Ramaswami, Hemant. A Novel Method for Accurate Evaluation of Size for Cylindrical Components.

Degree: MS, Engineering : Mechanical Engineering, 2010, University of Cincinnati

The objective of this thesis is to develop a methodology to calculate the size of a cylindrical profile accurately per ANSI standards. The ANSI Y 14.5.1M-1994 standard defines the size of a cylinder as the size of the largest ball rolling on a spine such that all points on the surface of the cylinder are external to it, or the size of the smallest ball rolling on a spine such that all points on the surface of the cylinder are internal to it. Current methods of size evaluation reduce the complexity of the spine and model it as a straight line. A novel methodology to evaluate the control points of the spine modeled as a Bezier curve or an Open Uniform B-Spline curve of a pre-specified degree based on points collected on the surface of the cylinder has been developed in this thesis. This provides a quantitative measure of the size of the cylinder in accordance with ANSI standards. The formulations to evaluate the maximum inscribing spine and the minimum circumscribing spine are presented as multi-level optimization problems. The outer level optimization is used to identify the optimal set of control points for the spline representing the path of the rolling ball. The inner level optimization is used to find the nearest point on the curve corresponding to every point in the dataset. The optimization formulation has been used to calculate the true size of cylinders for several published, simulated and real datasets. These results have been compared to traditional estimates for size of a cylinder, such as the maximum inscribed, minimum circumscribed and least squares cylinders. The results indicate that the method presented in this research conforms better to the ANSI standards as compared to the traditional methods. Further analysis is presented to observe the effect of sample size on the results of the algorithm. It is observed that with an increase in the sample size, the difference between the results of the presented algorithm and the traditional methods increases with the presented method providing more accurate estimates of the size of the cylinder. Advisors/Committee Members: Anand, Sundararaman (Committee Chair).

Subjects/Keywords: Mechanical Engineering; Size of a Cylinder; Actual Value; Open Uniform B-Spline Curve; B&233; zier Curve; Particle Swarm Optimization

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Ramaswami, H. (2010). A Novel Method for Accurate Evaluation of Size for Cylindrical Components. (Masters Thesis). University of Cincinnati. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=ucin1267548284

Chicago Manual of Style (16th Edition):

Ramaswami, Hemant. “A Novel Method for Accurate Evaluation of Size for Cylindrical Components.” 2010. Masters Thesis, University of Cincinnati. Accessed December 04, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1267548284.

MLA Handbook (7th Edition):

Ramaswami, Hemant. “A Novel Method for Accurate Evaluation of Size for Cylindrical Components.” 2010. Web. 04 Dec 2020.

Vancouver:

Ramaswami H. A Novel Method for Accurate Evaluation of Size for Cylindrical Components. [Internet] [Masters thesis]. University of Cincinnati; 2010. [cited 2020 Dec 04]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1267548284.

Council of Science Editors:

Ramaswami H. A Novel Method for Accurate Evaluation of Size for Cylindrical Components. [Masters Thesis]. University of Cincinnati; 2010. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1267548284

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