All ETDs from UAB

Advisory Committee Chair

Donald B Twieg

Advisory Committee Members

Allan C Dobbins

Rotem A Elgavish

Stanley J Reeves

Ernest M Stokely

Xincheng Yao

Document Type


Date of Award


Degree Name by School

Doctor of Philosophy (PhD) School of Engineering


Rapid and accurate mapping of relaxation rates applies to a number of neuroimaging and functional magnetic resonance imaging (fMRI) studies. Previously developed relaxation rate mapping methods are based mostly on non-linear fitting of intensity images. For the first time, this study developed an ultrafast and direct transverse relaxation rate mapping technique, Spin Echo Single-Shot Parameter Assessment by Retrieval from Single Encoding (SE-SS-PARSE). Four useful imaging parameters, local transverse magnetization magnitude (Mxy0), frequency (f), reversible and irreversible transverse re-laxation rate (R2' and R2), can be estimated using an iterative searching algorithm simul-taneously and quantitatively. In addition, the SE-SS-PARSE technique is free of geome-tric errors and blurring artifacts that commonly occur in the other SS techniques, such as echo planar imaging (EPI). Specifically, this work developed the signal model of SE-SS-PARSE and tested this technique with computer simulations, experimental phantoms and biological samples. In simulations, even at a noise level with low signal-to-noise ratio (SNR) of 20dB, SE-SS-PARSE is able to generate accurate local magnetization parameter maps subject to statis-tical comparison with actual parameter values. After successful testing with a numerical phantom, the SE-SS-PARSE technique was performed on a realistic four-tube phantom, which was designed to produce in-vivo-like and different R2 and R2' values in each tube. The estimated relaxation rates from SE-SS-PARSE were highly correlated with relaxation rates computed from slower "gold standard" conventional MRI methods (correlation coefficients r1=0.9636 for R2', r2=0.9788 for R2). The ultrafast SE-SS-PARSE tech-nique was also compared with a widely used T2-weighted imaging MRI technique, fast spin echo (FSE), in mapping R2 values. Four-tube phantom studies indicate that SE-SS-PARSE produces results with accuracy equivalent to FSE, but with a much shorter acqui-sition time. In addition, biological sample studies show that SE-SS-PARSE with fat satu-ration pulse produces more accurate R2 estimates than used without fat saturation when fat is present. In conclusion, SE-SS-PARSE is an ultrafast MRI method that can produce reliable R2 and R2' mapping. It is expected that SE-SS-PARSE will find important appli-cations in neuroimaging and fMRI studies, especially in recording rapidly changing phy-siological phenomena.

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Engineering Commons



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