Functional magnetic resonance imaging (fMRI) has revolutionized the neurosciences by providing noninvasive tools for monitoring changes in blood oxygenation or tissue perfusion associated with brain activation. The most common approach is blood oxygenation dependent (BOLD) imaging. Unfortunately, the MRI acquisition parameters that provide the oxygen sensitivity in BOLD also produce sensitivity to image artifacts, signal dropouts, and spatial distortion.
The aim of this proposal is to develop alternatives to BOLD without these limitations. The new methods described in this proposal are based on oxygen-dependent signal changes in rapid, short TR, fully refocused imaging acquisition techniques, known as steady-state free precession, or SSFP. These approaches exploit the changes in the steady-state signal due to oxygenation changes. Once this steady-state oxygenation dependent contrast has been established, it can be captured with any image encoding method, which can be chosen for efficiency, resolution, and immunity to artifacts. The result is high-resolution, isotropic in any area of the brain, without signal dropouts or spatial distortion. This will be an important addition to the tools available to neuroscientists for studying brain activation. Specifically, this project aims to develop two different approaches for exploiting the SSFP response for fMRI. The first uses the frequency sensitivity of the SSFP transition band to detect absolute frequency shifts from blood oxygenation changes. The second exploits oxygen-dependent apparent T2 changes to the steady state magnetization. These techniques will then be evaluated and compared with conventional BOLD in well characterized studies of the visual system. ? ? ?
|Jou, Tiffany; Patterson, Steve; Pauly, John M et al. (2016) Fat-suppressed alternating-SSFP for whole-brain fMRI using breath-hold and visual stimulus paradigms. Magn Reson Med 75:1978-88|
|Stikov, Nikola; Keenan, Kathryn E; Pauly, John M et al. (2011) Cross-relaxation imaging of human articular cartilage. Magn Reson Med 66:725-34|
|Stikov, Nikola; Perry, Lee M; Mezer, Aviv et al. (2011) Bound pool fractions complement diffusion measures to describe white matter micro and macrostructure. Neuroimage 54:1112-21|
|Lee, Jongho; Lustig, Michael; Kim, Dong-hyun et al. (2009) Improved shim method based on the minimization of the maximum off-resonance frequency for balanced steady-state free precession (bSSFP). Magn Reson Med 61:1500-6|
|Lee, Jin Hyung; Dumoulin, Serge O; Saritas, Emine U et al. (2008) Full-brain coverage and high-resolution imaging capabilities of passband b-SSFP fMRI at 3T. Magn Reson Med 59:1099-110|