Three-dimensional through-time radial GRAPPA for renal MR angiography

• Published in: Journal of magnetic resonance imaging Vol. 40; no. 4; pp. 864 - 874
• Main Authors: Wright, Katherine L., Lee, Gregory R., Ehses, Philipp, Griswold, Mark A., Gulani, Vikas, Seiberlich, Nicole
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.10.2014; Wiley Subscription Services, Inc
• Subjects: Adult; Algorithms; Blood Flow Velocity - physiology; Female; Humans; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; Imaging, Three-Dimensional - methods; Magnetic Resonance Angiography - methods; Magnetic resonance imaging; Male; non-Cartesian imaging; parallel imaging; radial GRAPPA; Renal Artery - anatomy & histology; Renal Artery - physiology; Renal Circulation - physiology; renal MRA; Reproducibility of Results; Sensitivity and Specificity; radial GRAPPA; parallel imaging; non-Cartesian imaging; renal MRA
• ISSN: 1053-1807; 1522-2586
• DOI: 10.1002/jmri.24439

Purpose To achieve high temporal and spatial resolution for contrast‐enhanced time‐resolved MR angiography exams (trMRAs), fast imaging techniques such as non‐Cartesian parallel imaging must be used. In this study, the three‐dimensional (3D) through‐time radial generalized autocalibrating partially parallel acquisition (GRAPPA) method is used to reconstruct highly accelerated stack‐of‐stars data for time‐resolved renal MRAs. Materials and Methods Through‐time radial GRAPPA has been recently introduced as a method for non‐Cartesian GRAPPA weight calibration, and a similar concept can also be used in 3D acquisitions. By combining different sources of calibration information, acquisition time can be reduced. Here, different GRAPPA weight calibration schemes are explored in simulation, and the results are applied to reconstruct undersampled stack‐of‐stars data. Results Simulations demonstrate that an accurate and efficient approach to 3D calibration is to combine a small number of central partitions with as many temporal repetitions as exam time permits. These findings were used to reconstruct renal trMRA data with an in‐plane acceleration factor as high as 12.6 with respect to the Nyquist sampling criterion, where the lowest root mean squared error value of 16.4% was achieved when using a calibration scheme with 8 partitions, 16 repetitions, and a 4 projection × 8 read point segment size. Conclusion 3D through‐time radial GRAPPA can be used to successfully reconstruct highly accelerated non‐Cartesian data. By using in‐plane radial undersampling, a trMRA can be acquired with a temporal footprint less than 4s/frame with a spatial resolution of approximately 1.5 mm × 1.5 mm × 3 mm. J. Magn. Reson. Imaging 2014;40:864–874. © 2014 Wiley Periodicals, Inc.