Comparison of phase-constrained parallel MRI approaches: Analogies and differences

Purpose Phase‐constrained parallel MRI approaches have the potential for significantly improving the image quality of accelerated MRI scans. The purpose of this study was to investigate the properties of two different phase‐constrained parallel MRI formulations, namely the standard phase‐constrained...

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Published in:Magnetic resonance in medicine Vol. 75; no. 3; pp. 1086 - 1099
Main Authors: Blaimer, Martin, Heim, Marius, Neumann, Daniel, Jakob, Peter M., Kannengiesser, Stephan, Breuer, Felix A.
Format: Journal Article
Language:English
Published: United States Blackwell Publishing Ltd 01.03.2016
Wiley Subscription Services, Inc
Subjects:
Algorithms
Analogies
Calibration
conjugate symmetry
Conjugates
ESPIRiT
Formulations
GRAPPA
Image processing
Image Processing, Computer-Assisted - methods
Image quality
Image reconstruction
Magnetic resonance imaging
Magnetic Resonance Imaging - instrumentation
Magnetic Resonance Imaging - methods
Mathematical analysis
parallel MRI
phase-constrained reconstruction
Robustness (mathematics)
Signal Processing, Computer-Assisted
virtual coil
phase-constrained reconstruction
GRAPPA
conjugate symmetry
virtual coil
parallel MRI
ESPIRiT
ISSN:0740-3194, 1522-2594, 1522-2594
Online Access:Get full text
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Summary:Purpose Phase‐constrained parallel MRI approaches have the potential for significantly improving the image quality of accelerated MRI scans. The purpose of this study was to investigate the properties of two different phase‐constrained parallel MRI formulations, namely the standard phase‐constrained approach and the virtual conjugate coil (VCC) concept utilizing conjugate k‐space symmetry. Methods Both formulations were combined with image‐domain algorithms (SENSE) and a mathematical analysis was performed. Furthermore, the VCC concept was combined with k‐space algorithms (GRAPPA and ESPIRiT) for image reconstruction. In vivo experiments were conducted to illustrate analogies and differences between the individual methods. Furthermore, a simple method of improving the signal‐to‐noise ratio by modifying the sampling scheme was implemented. Results For SENSE, the VCC concept was mathematically equivalent to the standard phase‐constrained formulation and therefore yielded identical results. In conjunction with k‐space algorithms, the VCC concept provided more robust results when only a limited amount of calibration data were available. Additionally, VCC‐GRAPPA reconstructed images provided spatial phase information with full resolution. Conclusions Although both phase‐constrained parallel MRI formulations are very similar conceptually, there exist important differences between image‐domain and k‐space domain reconstructions regarding the calibration robustness and the availability of high‐resolution phase information. Magn Reson Med 75:1086–1099, 2016. © 2015 Wiley Periodicals, Inc.
Bibliography:ark:/67375/WNG-PW36M817-J
ArticleID:MRM25685
istex:97EC7DC3DF5D24FA46C4E458717712245734C21C
Siemens Healthcare
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SourceType-Scholarly Journals-1
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ISSN:0740-3194
1522-2594
1522-2594
DOI:10.1002/mrm.25685