TY - JOUR
T1 - 4D flow imaging with 2D-selective excitation
AU - Wink, Clarissa
AU - Ferrazzi, Giulio
AU - Bassenge, Jean Pierre
AU - Flassbeck, Sebastian
AU - Schmidt, Simon
AU - Schaeffter, Tobias
AU - Schmitter, Sebastian
N1 - Publisher Copyright:
© 2019 International Society for Magnetic Resonance in Medicine
PY - 2019/9
Y1 - 2019/9
N2 - Purpose: 4D flow MRI permits to quantify non-invasively time-dependent velocity vector fields, but it demands long acquisition times. 2D-selective excitation allows to accelerate the acquisition by reducing the FOV in both phase encoding directions. In this study, we investigate 2D-selective excitation with reduced FOV imaging for fast 4D flow imaging while obtaining correct velocity quantification. Methods: Two different 2D-selective excitation pulses were designed using spiral k-space trajectories. Further, their isophase time point was analyzed using simulations that considered both stationary and moving spins. On this basis, the 2D-selective RF pulses were implemented into a 4D flow sequence. A flow phantom study and seven 4D flow in vivo measurements were performed to assess the accuracy of velocity quantification by comparing the proposed technique to non-selective and conventional 1D slab-selective excitation. Results: The isophase time point for spiral 2D-selective RF pulses was found to be located at the end of excitation for both stationary and moving spins. Based on that, 2D-selective excitation with reduced FOV allowed us to successfully quantify velocities both in a flow phantom and in vivo. In a flow phantom, the velocity difference (Formula presented.) between the smaller reduced FOV and the reference scan was similar to the inter-scan variability of (Formula presented.). In vivo, the differences in flow (P = 0.995) and flow volume (P = 0.469) between the larger reduced FOV and the reference scan were non-significant. By reducing the FOV by two-thirds, acquisition time was halved. Conclusion: A reduced field-of-excitation allows to limit the FOV and therefore shorten 4D flow acquisition times while preserving successful velocity quantification.
AB - Purpose: 4D flow MRI permits to quantify non-invasively time-dependent velocity vector fields, but it demands long acquisition times. 2D-selective excitation allows to accelerate the acquisition by reducing the FOV in both phase encoding directions. In this study, we investigate 2D-selective excitation with reduced FOV imaging for fast 4D flow imaging while obtaining correct velocity quantification. Methods: Two different 2D-selective excitation pulses were designed using spiral k-space trajectories. Further, their isophase time point was analyzed using simulations that considered both stationary and moving spins. On this basis, the 2D-selective RF pulses were implemented into a 4D flow sequence. A flow phantom study and seven 4D flow in vivo measurements were performed to assess the accuracy of velocity quantification by comparing the proposed technique to non-selective and conventional 1D slab-selective excitation. Results: The isophase time point for spiral 2D-selective RF pulses was found to be located at the end of excitation for both stationary and moving spins. Based on that, 2D-selective excitation with reduced FOV allowed us to successfully quantify velocities both in a flow phantom and in vivo. In a flow phantom, the velocity difference (Formula presented.) between the smaller reduced FOV and the reference scan was similar to the inter-scan variability of (Formula presented.). In vivo, the differences in flow (P = 0.995) and flow volume (P = 0.469) between the larger reduced FOV and the reference scan were non-significant. By reducing the FOV by two-thirds, acquisition time was halved. Conclusion: A reduced field-of-excitation allows to limit the FOV and therefore shorten 4D flow acquisition times while preserving successful velocity quantification.
KW - 4D flow
KW - fast imaging
KW - reduced FOV
KW - reduced FOX
KW - spatially selective 2D RF excitation
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U2 - 10.1002/mrm.27769
DO - 10.1002/mrm.27769
M3 - Article
C2 - 31002417
AN - SCOPUS:85064645571
SN - 0740-3194
VL - 82
SP - 886
EP - 900
JO - Magnetic resonance in medicine
JF - Magnetic resonance in medicine
IS - 3
ER -