title: Fast Imaging Technique for fMRI: Consecutive Multishot Echo Planar Imaging Accelerated with GRAPPA Technique.
abstract: This study was to evaluate the proposed consecutive multishot echo planar imaging (cmsEPI) combined with a parallel imaging technique in terms of signal-to-noise ratio (SNR) and acceleration for a functional imaging study. We developed cmsEPI sequence using both consecutively acquired multishot EPI segments and variable flip angles to minimize the delay between segments and to maximize the SNR, respectively. We also combined cmsEPI with the generalized autocalibrating partially parallel acquisitions (GRAPPA) method. Temporal SNRs were measured at different acceleration factors and number of segments for functional sensitivity evaluation. We also examined the geometric distortions, which inherently occurred in EPI sequence. The practical acceleration factors, R = 2 or R = 3, of the proposed technique improved the temporal SNR by maximally 18% in phantom test and by averagely 8.2% in in vivo experiment, compared to cmsEPI without parallel imaging. The data collection time was decreased in inverse proportion to the acceleration factor as well. The improved temporal SNR resulted in better statistical power when evaluated on the functional response of the brain. In this study, we demonstrated that the combination of cmsEPI with the parallel imaging technique could provide the improved functional sensitivity for functional imaging study, compensating for the lower SNR by cmsEPI.
authors.affiliation: Kansei Fukushi Research Institute, Tohoku Fukushi University, Sendai 989-3201, Japan ; Graduate School of Information Science, Tohoku University, Sendai 980-8579, Japan.
authors.forename: Daehun
authors.initials: D
authors.lastname: Kang
authors.affiliation: Kansei Fukushi Research Institute, Tohoku Fukushi University, Sendai 989-3201, Japan.
authors.forename: Yul-Wan
authors.initials: YW
authors.lastname: Sung
authors.affiliation: Neuroscience Research Institute and Department of Radiological Science, Gachon University, 1198 Kuwol-dong, Namdong-gu, Incheon 405-760, Republic of Korea.
authors.forename: Chang-Ki
authors.initials: CK
authors.lastname: Kang
mesh_terms: D001921:Brain / Q000033:anatomy & histology / Q000502:physiology; D017352:Echo-Planar Imaging / Q000379:methods; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio