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Magn Reson Med. 2015 Jun;73(6):2212-24. doi: 10.1002/mrm.25364. Epub 2014 Jul 17.

Pseudo-random center placement O-space imaging for improved incoherence compressed sensing parallel MRI.

Author information

1
Yale University, Department of Diagnostic Radiology, New Haven, Connecticut, USA.
2
Massachusetts General Hospital Martinos Center for Imaging, Boston, Massachusetts, USA.
3
Yale University, Department of Electrical Engineering, New Haven, Connecticut, USA.
4
Yale University, Department of Biomedical Engineering, New Haven, Connecticut, USA.
5
Yale University, Department of Neurosurgery, New Haven, Connecticut, USA.

Abstract

PURPOSE:

Nonlinear spatial encoding magnetic (SEM) field strategies such as O-space imaging have previously reported dispersed artifacts during accelerated scans. Compressed sensing (CS) has shown a sparsity-promoting convex program allows image reconstruction from a reduced data set when using the appropriate sampling. The development of a pseudo-random center placement (CP) O-space CS approach optimizes incoherence through SEM field modulation to reconstruct an image with reduced error.

THEORY AND METHODS:

The incoherence parameter determines the sparsity levels for which CS is valid and the related transform point spread function measures the maximum interference for a single point. The O-space acquisition is optimized for CS by perturbing the Z(2) strength within 30% of the nominal value and demonstrated on a human 3T scanner.

RESULTS:

Pseudo-random CP O-space imaging is shown to improve incoherence between the sensing and sparse domains. Images indicate pseudo-random CP O-space has reduced mean squared error compared with a typical linear SEM field acquisition method.

CONCLUSION:

Pseudo-random CP O-space imaging, with a nonlinear SEM field designed for CS, is shown to reduce mean squared error of images at high acceleration over linear encoding methods for a 2D slice when using an eight channel circumferential receiver array for parallel imaging.

KEYWORDS:

O-space; accelerated imaging; compressed sensing; incoherence; nonlinear gradient encoding; parallel imaging; sparsity; spatial encoding magnetic fields; transform point spread function

PMID:
25042143
PMCID:
PMC4297603
DOI:
10.1002/mrm.25364
[Indexed for MEDLINE]
Free PMC Article
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