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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 mm2. 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.
