Thomas Benkert1, Philipp Ehses2,3, Martin Blaimer1, Peter M Jakob1,4, Felix A Breuer1. 1. Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany. 2. Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany. 3. High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany. 4. Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany.
Abstract
PURPOSE: Balanced steady-state free precession (bSSFP) imaging suffers from banding artifacts due to its inherent sensitivity to inhomogeneities in the main magnetic field. These artifacts can be removed by the acquisition of multiple images at different frequency offsets. However, conventional phase-cycling is hindered by a long scan time. The purpose of this work is to present a novel approach for efficient banding removal in bSSFP imaging. THEORY AND METHODS: To this end, the phase-cycle during a single-shot radial acquisition of an image was dynamically changed. Thus, each projection is acquired with a different frequency offset. Using conventional radial gridding, an artifact-free image can be reconstructed out of this dataset. RESULTS: The approach is validated at clinical field strength [3.0 Tesla (T)] as well as at ultrahigh field (9.4T). Robust elimination of banding artifacts was obtained for different imaging regions, including brain imaging at ultrahigh field with an in-plane resolution of 0.25 × 0.25 mm(2). Besides banding artifact-free imaging, the applicability of the proposed technique for fat-water separation is demonstrated. CONCLUSION: Dynamically phase-cycled radial bSSFP has the potential for banding-free bSSFP imaging in a short scan time, in the presence of severe field inhomogeneities and at high resolution.
PURPOSE: Balanced steady-state free precession (bSSFP) imaging suffers from banding artifacts due to its inherent sensitivity to inhomogeneities in the main magnetic field. These artifacts can be removed by the acquisition of multiple images at different frequency offsets. However, conventional phase-cycling is hindered by a long scan time. The purpose of this work is to present a novel approach for efficient banding removal in bSSFP imaging. THEORY AND METHODS: To this end, the phase-cycle during a single-shot radial acquisition of an image was dynamically changed. Thus, each projection is acquired with a different frequency offset. Using conventional radial gridding, an artifact-free image can be reconstructed out of this dataset. RESULTS: The approach is validated at clinical field strength [3.0 Tesla (T)] as well as at ultrahigh field (9.4T). Robust elimination of banding artifacts was obtained for different imaging regions, including brain imaging at ultrahigh field with an in-plane resolution of 0.25 × 0.25 mm(2). Besides banding artifact-free imaging, the applicability of the proposed technique for fat-water separation is demonstrated. CONCLUSION: Dynamically phase-cycled radial bSSFP has the potential for banding-free bSSFP imaging in a short scan time, in the presence of severe field inhomogeneities and at high resolution.
Authors: Yi Wang; Xingfeng Shao; Thomas Martin; Steen Moeller; Essa Yacoub; Danny J J Wang Journal: Magn Reson Med Date: 2015-12-15 Impact factor: 4.668
Authors: Yulia Shcherbakova; Cornelis A T van den Berg; Chrit T W Moonen; Lambertus W Bartels Journal: Magn Reson Med Date: 2017-05-22 Impact factor: 4.668