Flip-angle map calculation via keyhole reconstruction in uniform and variable-density 2D-spiral hyperpolarized 129Xe MRI
Joseph W Plummer1,2, Abdullah S Bdaiwi1,2, Mariah L Costa1,2, Matthew M Willmering1, Zackary I Cleveland1,2,3, and Laura L Walkup1,2,3,4
1Center for Pulmonary Imaging Research, Department of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, 2Biomedical Engineering, University of Cincinnati, Cincinnati, OH, United States, 3Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, 4Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
Hyperpolarized 129Xe-MRI is prone to B1-inhomogeneity-induced signal artifacts, that often obscure pulmonary abnormalities. B1-inhomeogeneity can be corrected by calculating a flip-angle map and rescaling the images. Current methods to acquire a flip-angle map in 2D-spiral sequences require two-successive images to be collected in a single breath-hold, doubling scan duration. We demonstrate that flip-angle maps can be calculated from a single image acquisition using keyhole reconstruction. Furthermore, analytical methods can be used to minimize the amount of required oversampling. This approach enables accurate B1-artifact correction, with minimal impact to scan-duration, making it especially useful for short breath-hold studies.
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