Separation of parallel encoded complex-valued slices (SPECS) from a single complex-valued aliased coil image

Abstract Purpose Achieving a reduction in scan time with minimal inter-slice signal leakage is one of the significant obstacles in parallel MR imaging. In fMRI, multiband-imaging techniques accelerate data acquisition by simultaneously magnetizing the spatial frequency spectrum of multiple slices. T...

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Bibliographic Details
Published in:Magnetic resonance imaging 2016-04, Vol.34 (3), p.359-369
Main Authors: Rowe, Daniel B, Bruce, Iain P, Nencka, Andrew S, Hyde, James S, Kociuba, Mary C
Format: Article
Language:English
Subjects:
Algorithms
Brain - diagnostic imaging
Brain - physiology
Brain Mapping - methods
Calibration
Computer Simulation
Echo-Planar Imaging
fMRI
Fourier Analysis
Humans
Image Enhancement - methods
Image Interpretation, Computer-Assisted - methods
Image Processing, Computer-Assisted - methods
Magnetic Resonance Imaging
MRI
Multiband
Parallel slice
Phantoms, Imaging
Radiology
Simultaneous multi-slice (SMS)
SPECS
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Summary:Abstract Purpose Achieving a reduction in scan time with minimal inter-slice signal leakage is one of the significant obstacles in parallel MR imaging. In fMRI, multiband-imaging techniques accelerate data acquisition by simultaneously magnetizing the spatial frequency spectrum of multiple slices. The SPECS model eliminates the consequential inter-slice signal leakage from the slice unaliasing, while maintaining an optimal reduction in scan time and activation statistics in fMRI studies. Materials and methods When the combined k -space array is inverse Fourier reconstructed, the resulting aliased image is separated into the un-aliased slices through a least squares estimator. Without the additional spatial information from a phased array of receiver coils, slice separation in SPECS is accomplished with acquired aliased images in shifted FOV aliasing pattern, and a bootstrapping approach of incorporating reference calibration images in an orthogonal Hadamard pattern. Result The aliased slices are effectively separated with minimal expense to the spatial and temporal resolution. Functional activation is observed in the motor cortex, as the number of aliased slices is increased, in a bilateral finger tapping fMRI experiment. Conclusion The SPECS model incorporates calibration reference images together with coefficients of orthogonal polynomials into an un-aliasing estimator to achieve separated images, with virtually no residual artifacts and functional activation detection in separated images.
ISSN:0730-725X
1873-5894
DOI:10.1016/j.mri.2015.11.003