Advisory Committee Chair
Donald B Twieg
Advisory Committee Members
Narasimha S Akella
Georg Deutsch
Allan C Dobbins
Alfred L Paige
Stanley J Reeves
Document Type
Dissertation
Date of Award
2010
Degree Name by School
Doctor of Philosophy (PhD) School of Engineering
Abstract
Fast imaging Magnetic Resonance Imaging (MRI) techniques such as Echo Planar Imaging (EPI) often suffer from artifacts such as signal dropouts, geometric distortions and susceptibility artifacts due to background gradients. Parameter Assessment by Retrieval from Signal Encoding (PARSE) was introduced as a single shot, inverse estimation technique that models the MRI process more accurately and estimates the initial transverse magnetization, M0 and its phase, the decay rate R2* and local frequency at each pixel. This technique is devoid of the aforementioned artifacts seen in EPI techniques. The goal of this work is to develop multi-shot parameter assessment by retrieval from signal encoding (MS-PARSE) techniques for higher resolution. In the first part, the MS-PARSE technique is implemented and tested using interleaved rosette shots. A modified progressive length conjugate gradient (PLCG) algorithm was developed to combine the multi-shot data and reconstruct high resolution parameter maps. Numerical simulations were carried out to assess the performance of the algorithm. The MS-PARSE sequence was programmed on a 4.7 T MRI scanner, the k- trajectory was calibrated and phantom data were collected. High resolution parameter maps were reconstructed. The R2* parameter maps from the experimental data were validated with reference values and are shown to correlate very well with `gold-standard' R2* measurement technique. The next part describes the extension of the MS-PARSE technique to parallel imaging. This paper describes the implementation of the PLCG algorithm to handle PARSE data from multiple coils and multiple shots. A multiple-coil data acquisition was simulated using a discrete numerical phantom with overlapping spatial sensitivity profiles. Numerical simulations were carried out to assess the performance of the algorithm under different noise conditions. The accuracy of the estimated parameters are compared with assigned reference values. We demonstrate that the technique can produce high-resolution multi-parameter maps from an acquisition lasting a few hundred milliseconds. The development of the above multi-shot PARSE techniques allows the generation of high spatial and temporal resolution multi-parameter maps. Upon validation, these techniques can potentially benefit functional MRI and a number of clinical MRI imaging applications.
Recommended Citation
Menon, Rajiv G., "Development of Multi-Shot PARSE MRI Techniques" (2010). All ETDs from UAB. 2463.
https://digitalcommons.library.uab.edu/etd-collection/2463