DiCarlo Julie C, Hargreaves Brian A, Nayak Krishna S, Hu Bob S, Pauly John M, Nishimura Dwight G
Department of Electrical Engineering, Stanford University, Stanford, California 94305-9510, USA.
Magn Reson Med. 2005 Sep;54(3):645-55. 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.
在具有高度脉动和湍流的区域，具有高时间、空间和速度分辨率的实时成像至关重要。先前已证明使用一维傅里叶速度编码（FVE）进行实时速度测量，失谐产生的影响较小。建议应用可变密度采样来改善速度测量，而不会显著增加读出时间或增加混叠伪影。给出了两个序列比较，以提高速度分辨率或增加速度视野（FOV），从而在不产生混叠的情况下明确测量高达5 m/s的速度。展示了来自管流模型、狭窄模型和健康志愿者的结果，以及与使用多普勒超声（US）测量结果的比较。研究证实，kz-kv空间的可变密度采集可提高此类数据的速度分辨率和FOV，对改善FOV以纳入狭窄范围内的速度影响最大。
