Balanced steady-state free precession (SSFP) is an MRI pulse sequence that is widely used for cardiac imaging, because it provides superior SNR and excellent contrast between blood and myocardium compared to the alternatives. Its primary drawback is sensitivity to off-resonance, which is related to the reciprocal of the sequence repetition time (TR) and results in banding artifacts.
In this thesis, I introduce a novel technique that overcomes this limitation, and apply it to two clinically important cardiac imaging applications. The new technique, called wideband SSFP, utilizes two alternating repetition times to establish a steady state that is more resistant to banding artifacts, because the spacing between nulls in its frequency response is up to twice as large as that of conventional balanced SSFP.Wideband SSFP provides an efficient scheme for acquiring SSFP cardiac images with long readouts, which allows the high SNR of SSFP to be used for achieving higher spatial resolution. This technique is particularly suited for higher field strengths (such as 3 Tesla).
A theoretical description of wideband SSFP is provided, including its spectral response, contrast, and SNR efficiency, with phantom experiments demonstrating excellent agreement between simulation and measurement. I then describe an initial magnetization preparation scheme based on scaled Kaiser-Bessel windowing functions to optimally stabilize the alternating-TR SSFP signal. Successful implementations of wideband SSFP for left ventricular function imaging and high-resolution coronary artery imaging in humans at 3 Tesla are then presented. In both cases, wideband SSFP provided improved spatial resolution and reduced image artifact, while maintaining a blood-myocardium contrast comparable to conventional balanced SSFP.
|Advisor:||Nayak, Krishna S.|
|Commitee:||Leahy, Richard M., Reisler, Hanna|
|School:||University of Southern California|
|School Location:||United States -- California|
|Source:||DAI-B 69/12, Dissertation Abstracts International|
|Subjects:||Biomedical engineering, Electrical engineering|
|Keywords:||Alternating repetition time, Cardiac MRI, Coronary artery imaging, Initial preparation, LV function, Steady-state free precession, Wideband SSFP|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be