Dynamically phase-cycled radial balanced SSFP imaging for efficient banding removal.
OBJECTIVE
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.


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.


CONCLUSIONS
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.
Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany.
Thomas
T
Benkert
Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany.|High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
Philipp
P
Ehses
Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany.
Martin
M
Blaimer
Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany.|Department of Experimental Physics 5, University of Würzburg, Würzburg, Germany.
Peter M
PM
Jakob
Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany.
Felix A
FA
Breuer
D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
SSFP; banding artifacts; fat-water separation; phase-cycling; radial imaging; steady-state