Implementation of Wavelet Encoding Spectroscopic Imaging Technique on a 3 Tesla Whole Body MR Scanner.

摘要

Magnetic Resonance Imaging (MRI) uses a magnetic field and low energy radio waves to visualize the internal structure and function of the body. This is one of the most popular technologies currently used for diagnostic imaging. Magnetic Resonance Spectroscopy Imaging (MRSI), complementing MRI, provides a chemical map of the scanned region by providing spatial information about tissue metabolite concentrations. MRSI is being used for early diagnostics to differentiate diseased tissue from normal tissue. However, obtaining metabolic maps with high spatial resolution requires long acquisition times where the patient has to lie still inside the magnet bore (scanner) especially if classical Chemical Shift Imaging (CSI) is used. The need for acquisition time reduction is encountered in many practical applications. In this dissertation, a 3D wavelet based encoding spectroscopic method (WE-SI) is investigated and implemented on a 3 Tesla Siemens Scanner. Compared to CSI, the proposed method is able to reduce acquisition time, and preserves the spatial metabolite distribution. As expected, a decrease in Signal to Noise Ratio (SNR) is noticed in WE-SI data compared to CSI. The dissertation explores important physical principles in MRI and spectroscopic imaging as a background, following by introduction of the wavelet encoding theory and comparison to Fourier encoding. In chapter 3, the implementation of WE-SI on a 3T scanner is detailed. In-vitro and in-vivo results are displayed and discussed in chapter 4, followed by conclusion.