title: Imaging with referenceless distortion correction and flexible regions of interest using single-shot biaxial spatiotemporally encoded MRI.
abstract: Owing to its intrinsic characteristics, spatiotemporally encoded (SPEN) imaging is less sensitive to adverse effects due to field inhomogeneity in comparison with echo planar imaging, a feature highly desired for functional, diffusion, and real-time MRI. However, the quality of images obtained with SPEN MRI is still degraded by geometric distortions when field inhomogeneity exists. In this study, a single-shot biaxial SPEN (bi-SPEN) pulse sequence is implemented, utilizing a 90° and a 180° chirp pulse incorporated with two orthogonal gradients. A referenceless geometric-distortion correction based on the single-shot bi-SPEN sequence is then proposed. The distorted image acquired with the single-shot bi-SPEN sequence is corrected by iterative super-resolved reconstruction involving the field gradients estimated from a field map, which in turn is obtained from its own super-resolved data after a phase-unwrapping procedure without additional scans. In addition, the distortion correction method is applied to improve the quality of the multiple region-of-interest images obtained with single-shot bi-SPEN sequence.
authors.affiliation: Department of Electronics Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen 361005, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Electronics Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen 361005, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Electronics Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen 361005, China. Electronic address: shcai@xmu.edu.cn.
authors.forename: Shuhui
authors.initials: S
authors.lastname: Cai
authors.affiliation: Department of Communication Engineering, Xiamen University, Xiamen 361005, China. Electronic address: cbcai@xmu.edu.cn.
authors.forename: Congbo
authors.initials: C
authors.lastname: Cai
authors.affiliation: Department of Imaging Sciences, University of Rochester, Rochester, NY 14642, USA.
authors.forename: Jianhui
authors.initials: J
authors.lastname: Zhong
authors.affiliation: Department of Electronics Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen 361005, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000465:Algorithms; D000818:Animals; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D051381:Rats
keywords: Biaxial spatiotemporal encoding; Iterative reconstruction; Referenceless distortion correction; Region-of-interest imaging; Super-resolved reconstruction; Ultrafast MRI