Martin Uecker1,2, Michael Lustig3. 1. Institute for Diagnostic and Interventional Radiology, University Medical Center Göttingen, Göttingen, Germany. 2. German Centre for Cardiovascular Research (DZHK), Partner site Göttingen, Göttingen, Germany. 3. Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA.
Abstract
PURPOSE: To develop an ESPIRiT-based method to estimate coil sensitivities with image phase as a building block for efficient and robust image reconstruction with phase constraints. THEORY AND METHODS: ESPIRiT is a new framework for calibration of the coil sensitivities and reconstruction in parallel magnetic resonance imaging. Applying ESPIRiT to a combined set of physical and virtual conjugate coils (VCC-ESPIRiT) implicitly exploits conjugate symmetry in k-space similar to VCC-GRAPPA. Based on this method, a new post-processing step is proposed for the explicit computation of coil sensitivities that include the absolute phase of the image. The accuracy of the computed maps is directly validated using a test based on projection onto fully sampled coil images and also indirectly in phase-constrained parallel-imaging reconstructions. RESULTS: The proposed method can estimate accurate sensitivities which include low-resolution image phase. In case of high-frequency phase variations VCC-ESPIRiT yields an additional set of maps that indicates the existence of a high-frequency phase component. Taking this additional set of maps into account can improve the robustness of phase-constrained parallel imaging. CONCLUSION: The extended VCC-ESPIRiT is a useful tool for phase-constrained imaging. Magn Reson Med 77:1201-1207, 2017.
PURPOSE: To develop an ESPIRiT-based method to estimate coil sensitivities with image phase as a building block for efficient and robust image reconstruction with phase constraints. THEORY AND METHODS: ESPIRiT is a new framework for calibration of the coil sensitivities and reconstruction in parallel magnetic resonance imaging. Applying ESPIRiT to a combined set of physical and virtual conjugate coils (VCC-ESPIRiT) implicitly exploits conjugate symmetry in k-space similar to VCC-GRAPPA. Based on this method, a new post-processing step is proposed for the explicit computation of coil sensitivities that include the absolute phase of the image. The accuracy of the computed maps is directly validated using a test based on projection onto fully sampled coil images and also indirectly in phase-constrained parallel-imaging reconstructions. RESULTS: The proposed method can estimate accurate sensitivities which include low-resolution image phase. In case of high-frequency phase variations VCC-ESPIRiT yields an additional set of maps that indicates the existence of a high-frequency phase component. Taking this additional set of maps into account can improve the robustness of phase-constrained parallel imaging. CONCLUSION: The extended VCC-ESPIRiT is a useful tool for phase-constrained imaging. Magn Reson Med 77:1201-1207, 2017.
Authors: Charles A McKenzie; Ernest N Yeh; Michael A Ohliger; Mark D Price; Daniel K Sodickson Journal: Magn Reson Med Date: 2002-03 Impact factor: 4.668
Authors: Martin Blaimer; Marcel Gutberlet; Peter Kellman; Felix A Breuer; Herbert Köstler; Mark A Griswold Journal: Magn Reson Med Date: 2009-01 Impact factor: 4.668
Authors: Martin Blaimer; Marius Heim; Daniel Neumann; Peter M Jakob; Stephan Kannengiesser; Felix A Breuer Journal: Magn Reson Med Date: 2015-04-04 Impact factor: 4.668
Authors: Guobin Li; Jürgen Hennig; Esther Raithel; Martin Büchert; Dominik Paul; Jan G Korvink; Maxim Zaitsev Journal: MAGMA Date: 2015-02-26 Impact factor: 2.310
Authors: Martin Uecker; Peng Lai; Mark J Murphy; Patrick Virtue; Michael Elad; John M Pauly; Shreyas S Vasanawala; Michael Lustig Journal: Magn Reson Med Date: 2014-03 Impact factor: 4.668