title: Improving the spatial resolution of magnetic resonance inverse imaging via the blipped-CAIPI acquisition scheme.
abstract: Using simultaneous acquisition from multiple channels of a radio-frequency (RF) coil array, magnetic resonance inverse imaging (InI) achieves functional MRI acquisitions at a rate of 100ms per whole-brain volume. InI accelerates the scan by leaving out partition encoding steps and reconstructs images by solving under-determined inverse problems using RF coil sensitivity information. Hence, the correlated spatial information available in the coil array causes spatial blurring in the InI reconstruction. Here, we propose a method that employs gradient blips in the partition encoding direction during the acquisition to provide extra spatial encoding in order to better differentiate signals from different partitions. According to our simulations, this blipped-InI (bInI) method can increase the average spatial resolution by 15.1% (1.3mm) across the whole brain and from 32.6% (4.2mm) in subcortical regions, as compared to the InI method. In a visual fMRI experiment, we demonstrate that, compared to InI, the spatial distribution of bInI BOLD response is more consistent with that of a conventional echo-planar imaging (EPI) at the level of individual subjects. With the improved spatial resolution, especially in subcortical regions, bInI can be a useful fMRI tool for obtaining high spatiotemporal information for clinical and cognitive neuroscience studies.
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, USA; Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
authors.forename: Wei-Tang
authors.initials: WT
authors.lastname: Chang
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, USA.
authors.forename: Kawin
authors.initials: K
authors.lastname: Setsompop
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, USA.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Ahveninen
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA.
authors.forename: John W
authors.initials: JW
authors.lastname: Belliveau
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Witzel
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan. Electronic address: fhlin@ntu.edu.tw.
authors.forename: Fa-Hsuan
authors.initials: FH
authors.lastname: Lin
mesh_terms: D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D002540:Cerebral Cortex / Q000502:physiology; D017352:Echo-Planar Imaging / Q000379:methods; D004574:Electromagnetic Fields; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D059906:Neuroimaging / Q000295:instrumentation / Q000379:methods*; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio
chemical_list: D010100:Oxygen
keywords: Blip; CAIPIRINHA; Inverse imaging; Parallel imaging