Radial k-t SPIRiT: Autocalibrated parallel imaging for generalized phase-contrast MRI

• Published in: Magnetic resonance in medicine Vol. 72; no. 5; pp. 1233 - 1245
• Main Authors: Santelli, Claudio, Schaeffter, Tobias, Kozerke, Sebastian
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.11.2014; Wiley Subscription Services, Inc
• Subjects: Aorta, Thoracic - anatomy & histology; autocalibration; Calibration; Humans; Image Enhancement - methods; Image Processing, Computer-Assisted - methods; iterative reconstruction; Magnetic Resonance Imaging, Cine - methods; parallel imaging; phase-contrast; Sensitivity and Specificity; turbulent kinetic energy; velocity mapping; parallel imaging; phase-contrast; iterative reconstruction; velocity mapping; turbulent kinetic energy; autocalibration
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.25030

Purpose To extend SPIRiT to additionally exploit temporal correlations for highly accelerated generalized phase‐contrast MRI and to compare the performance of the proposed radial k‐t SPIRiT method relative to frame‐by‐frame SPIRiT and radial k‐t GRAPPA reconstruction for velocity and turbulence mapping in the aortic arch. Theory and Methods Free‐breathing navigator‐gated two‐dimensional radial cine imaging with three‐directional multi‐point velocity encoding was implemented and fully sampled data were obtained in the aortic arch of healthy volunteers. Velocities were encoded with three different first gradient moments per axis to permit quantification of mean velocity and turbulent kinetic energy. Velocity and turbulent kinetic energy maps from up to 14‐fold undersampled data were compared for k‐t SPIRiT, frame‐by‐frame SPIRiT, and k‐t GRAPPA relative to the fully sampled reference. Results Using k‐t SPIRiT, improvements in magnitude and velocity reconstruction accuracy were found. Temporally resolved magnitude profiles revealed a reduction in spatial blurring with k‐t SPIRiT compared with frame‐by‐frame SPIRiT and k‐t GRAPPA for all velocity encodings, leading to improved estimates of turbulent kinetic energy. Conclusion k‐t SPIRiT offers improved reconstruction accuracy at high radial undersampling factors and hence facilitates the use of generalized phase‐contrast MRI for routine use. Magn Reson Med 72:1233–1245, 2014. © 2013 Wiley Periodicals, Inc.