This dissertation, "Experimental and Theoretical Studies of Twin Drivers and Biopsy Needle Driver for MR Elastography With Applications" by Ying, Zheng, 鄭穎, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Experimental and Theoretical Studies of Twin Drivers and Biopsy Needle Driver in MR Elastography Applications Submitted by Zheng Ying for the degree of Master of Philosophy at The University of Hong Kong in Aug 2007 Magnetic Resonance Elastography (MRE) is a novel technique for visualizing propagating shear waves in an object and quantitatively depicting the mechanical properties of tissues. MRE has many in vivo applications, notably in the visualization of the human brain, breast, liver, prostate, skeletal muscle and vascular wall. Most precious studies have used a single driver placed on the surface of tissues to generate wave propagation, but this method has several disadvantages. The wave generated by a single driver can be blocked by bone or fluid structures. It is also subject to attenuation, with the result that it may illuminate only a small region of interest (ROI) and be unable to reach deep structures. In some applications, however, it is necessary to obtain well-defined wave patterns that can illuminate arteries behind veins, the whole brain, and ROI deep in tissues. In this work, a twin-driver set for MRE has been developed. The experimental results demonstrated that the stiffness values obtained by MRE using the twin-driver set correlate well with those obtained by compression test. Comparison between MRE wave images acquired by twin- and single-driver sets indicates that shear waves generated by the twin-driver set can illuminate a larger region. A finite element model named Comsol Multiphysics was used to simulate single- and twin- driver datasets, and the same wave images were obtained in the experiments. This study also shows that MR Interference Elastography with the twin drivers offers advantages over a single driver in obtaining a more homogeneous and accurate elastogram of tissues, and can illuminate ROI blocked by other structures. The feasibility of MRE using a twin-driver set on femoral artery study is also demonstrated. The twin-driver set is a potentially useful tool for illuminating objects blocked by stiff or fluid structures. The twin pneumatic drivers also offer advantages over a single pneumatic driver in obtaining accurate stiffness and illuminating large ROI. The results from the phantom study and Comsol Multiphysics modeling both indicate that using twin pneumatic drivers can effectively compensate for the attenuation of shear wave propagation. The feasibility of using twin pneumatic drivers for brain MRE has been demonstrated by an in vivo experiment. The study on whole brain by MRE can help doctors detect Alzheimer's disease (AD) early. A novel biopsy needle driver is applied in an MRE phantom and an in vivo rabbit study. The results show that using biopsy needle as the MRE driver can provide stiffness values of phantoms that correlate well with the values provided by compression test, and can precisely detect the shape and location of an inclusion in the phantom and a tumor embedded in a rabbit's thigh muscle. MRI-guided needle biopsies in real-time MRE may be a potential diagnostic tool for breast, liver and kidney cancer in the future. (An abstract of exactly 458 words) Signature: __________________________ Zheng Ying DOI: 10.5353/th_b3955823 Subjects: Cancer - Magnetic resonance imaging Needle biopsy