Development and optimization of high resolution multi-shot magnetic resonance acquisitions for diffusion weighted imaging

Magnetic Resonance Imaging;Diffusion Weighted Imaging;Magnetic Resonance Elastography

Holtrop, Joseph

关键词: Magnetic Resonance Imaging;    Diffusion Weighted Imaging;    Magnetic Resonance Elastography;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/92833/HOLTROP-DISSERTATION-2016.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Diffusion Weighted Imaging (DWI) has become a valuable tool for imaging tissue microstructure, finding use in both clinical and research settings.In order to better resolve finer structures it is desirable to acquire images with higher resolutions.Achieving higher resolutions in diffusion imaging faces several challenges with the primary challenges being low signal to noise ratio and motion induced phase errors.The work in this thesis aims at creating an acquisition that is able to image with a high SNR efficiency in order to achieve higher resolutions.This is accomplished through the use 3D excitations in order to optimize the repetition time in order to operate in a signal to noise ratio efficient regime. High SNR efficiency is also achieved by minimizing TE through the use of spiral readouts. In conjunction with the signal to noise ratio efficiency is the need for motion correction in high resolution diffusion imaging.In this work, the requirements for performing motion correction are analyzed through simulation and in-vivo experiments.The work on motion correction demonstrated the impact that b-value, gradient strength, and cardiac pulsation have on motion induced phase error correction.Results show that a 6 mm resolution navigator is sufficient for correction of motion induced phase errors due to cardiac pulsation at a b-value of 1000 s/mm2 on most current hardware systems.By combining all the methods used in this dissertation, a high quality diffusion weighted imaging approach that uses a novel pulse sequence was developed that has produced high quality diffusion weighted images at a 0.8 mm isotropic resolution.Additionally this work takes several of the advances used in diffusion weighted imaging and applies them to magnet resonance elastography in order to improve the resolution and spatial coverage achievable with magnetic resonance elastography.