Tiffany Jou successfully defends dissertation
Functional Magnetic Resonance Imaging (fMRI) is a powerful noninvasive tool for mapping brain activity. Currently, the most widely used methods to acquire fMRI images are T2*-weighted Gradient-Echo (GRE) sequences. These methods exhibit excellent sensitivity to blood oxygenation level-dependent (BOLD) contrast. However, GRE sequences require a long echo time (TE) for good BOLD sensitivity and use long, single-shot readouts for efficiency, resulting in signal dropout and image distortion in regions near air–tissue interfaces such as the orbitofrontal cortex and inferior temporal regions. Recent studies have shown that passband steady-state free precession (pb-SSFP) fMRI is a promising alternative. However, banding artifacts remain a challenge for whole-brain imaging, as current solutions are impractical for many functional studies.
In this talk, I will introduce an improved pb-SSFP fMRI technique called Alternating-SSFP (Alt-SSFP), which permits whole-brain, banding-artifact-free-SSFP fMRI in a single scan. First, I will go over the pulse sequence development needed to make the method robust for human fMRI studies. Next, I will describe a design of a short spatial-spectral RF pulse that reduces artifacts associated with bright fat signal and increases temporal SNR for alt-SSFP fMRI. Lastly, I will describe an improved image reconstruction method for alt-SSFP using the alternate banding patterns for parallel imaging, which would allow greater acceleration for higher temporal and/or spatial resolution. These combined developments result in a practical pbSSFP fMRI method capable of functional imaging in regions currently inaccessible to conventional fMRI acquisition methods. This could potentially become a powerful tool for better understanding how different parts of the brain are interconnected, and for studying the brain in its entirety.