Variable-density one-shot fourier velocity encoding

• Published in: Magnetic resonance in medicine 2005-09, Vol.54 (3), p.645-655
• Main Authors: DiCarlo, Julie C., Hargreaves, Brian A., Nayak, Krishna S., Hu, Bob S., Pauly, John M., Nishimura, Dwight G.
• Format: Article
• Language: English
• Subjects: Aorta, Abdominal - physiology; Blood Flow Velocity - physiology; Constriction, Pathologic - diagnostic imaging; Constriction, Pathologic - physiopathology; Fourier Analysis; Fourier velocity encoding; Hemorheology - instrumentation; Humans; magnetic resonance imaging; peak velocity; Phantoms, Imaging; quantitative flow imaging; Signal Processing, Computer-Assisted; Ultrasonography, Doppler; variable-density sampling
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.20594

In areas of highly pulsatile and turbulent flow, real‐time imaging with high temporal, spatial, and velocity resolution is essential. The use of 1D Fourier velocity encoding (FVE) was previously demonstrated for velocity measurement in real time, with fewer effects resulting from off‐resonance. The application of variable‐density sampling is proposed to improve velocity measurement without a significant increase in readout time or the addition of aliasing artifacts. Two sequence comparisons are presented to improve velocity resolution or increase the velocity field of view (FOV) to unambiguously measure velocities up to 5 m/s without aliasing. The results from a tube flow phantom, a stenosis phantom, and healthy volunteers are presented, along with a comparison of measurements using Doppler ultrasound (US). The studies confirm that variable‐density acquisition of kz‐kv space improves the velocity resolution and FOV of such data, with the greatest impact on the improvement of FOV to include velocities in stenotic ranges. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.