Imaging the local mechanical properties of the brain with high-resolution magnetic resonance elastography

Mechanical properties of the human brain reflect the composition and organization of the complex tissue microstructure. Neurodegeneration involves alteration of this microstructure through a number of processes including neuronal cell death; glial matrix disruption and demyelination; and inflammatory cell infiltration. Assessment of neurological conditions requires imaging methods sensitive to microstructure and specific to neurodegenerative process. The noninvasive measurement of mechanical properties may provide this microstructural sensitivity necessary to improve early detection, differential diagnosis, and monitoring of disease progression. Magnetic resonance elastography (MRE) is a shear wave imaging technique that provides reliable, noninvasive estimates of tissue stiffness. MRE has been developed for many applications, and clinical practice has adopted MRE for the detection and staging of liver fibrosis. While the application of MRE to study the human brain in vivo has produced promising results, studies have been limited to reporting only global mechanical properties because of poor imaging spatial resolution and the complexity of the inverse problem associated with biomechanical property estimation. Increasing the clinical utility of MRE for assessing neurological disorders requires methodologies to obtain local estimates of brain tissue mechanical properties. The research presented in this dissertation focuses on the development of imaging strategies for MRE to enable the reliable estimation of local mechanical properties of the brain in vivo. Specifically, I present acquisition schemes for capturing shear displacement data at high-resolution. The use of these acquisitions on healthy human volunteers revealed neuroanatomical information previously unavailable from global MRE. Quantification of the local mechanical properties of the corpus callosum and corona radiata, two clinically relevant structures in the brain white matter, demonstrated that the measures agree with expected mechanical behavior based on underlying tissue microstructure. From these findings I conclude that high-resolution acquisitions provide reliable local property measures that may improve MRE studies of neurodegeneration and increase the utility of MRE as a clinical tool and quantitative microstructural imaging technique.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2013

Author dc:creator

• Johnson, Curtis L.

Contributors dc:contributor

• Georgiadis, John G.
• Sutton, Bradley P.
• Liang, Zhi-Pei
• Saif, M. Taher A.
• Olivero, William C.
• Wang, Huan

• Magnetic resonance elastography
• Brain
• Stiffness
• High-resolution
• White matter
• Corpus callosum

Statement dc:rights

• Copyright 2013 by Curtis Laurence Johnson

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/45396

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/45396