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Download fileUltra-High Field MR Diffusion Tensor Imaging Characterization of Rabbit Tendons and Ligaments
thesis
posted on 2012-12-10, 00:00 authored by Aman GuptaTendons 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
organization. Fiber tractography graphically supplements the
quantitative DTI data. The quantitative and graphical capabilities of
DTI provide more rigorous information regarding tendon and ligament
structural integrity in comparison to conventional MRI.
History
Advisor
Magin, Richard L.Department
BioengineeringDegree Grantor
University of Illinois at ChicagoDegree Level
- Doctoral
Committee Member
Wang, Vincent M. Stebbins, Glenn T. Royston, Thomas J. Akpa, Belinda S. Zelazny, Anthony M.Submitted date
2012-05Language
- en