Schmitter Sebastian, Adriany Gregor, Waks Matt, Moeller Steen, Aristova Maria, Vali Alireza, Auerbach Edward J, Van de Moortele Pierre-François, Ugurbil Kamil, Schnell Susanne
Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA.
Physikalisch-Technische Bundesanstalt, Braunschweig and Berlin, Germany.
Magn Reson Med. 2020 Oct;84(4):1947-1960. doi: 10.1002/mrm.28256. Epub 2020 Mar 18.
Simultaneous multislab (SMSb) 4D flow MRI was developed and implemented at 7T for accelerated acquisition of the 3D blood velocity vector field in both carotid bifurcations.
SMSb was applied to 4D flow to acquire blood velocities in both carotid bifurcations in sagittal orientation using a local transmit/receive coil at 7T. transmit efficiency was optimized by shimming. SMSb 4D flow was obtained in 8 healthy subjects in single-band (SB) and multiband (MB) fashion. Additionally, MB data were retrospectively undersampled to simulate GRAPPA R = 2 (MB2_GRAPPA2), and both SB datasets were added to form an artificial MB dataset (SumSB). The band separation performance was quantified by signal leakage. Peak velocity and total flow values were calculated and compared to SB via intraclass correlation analysis (ICC).
Clean slab separation was achieved yielding a mean signal leakage of 13% above the mean SB noise level. Mean total flow for MB2, SumSB, and MB_GRAPPA2 deviated less than 9% from the SB values. Peak velocities averaged over all vessels and subjects were 0.48 ± 0.11 m/s for SB, 0.47 ± 0.12 m/s for SumSB, 0.50 ± 0.13 m/s for MB2, and 0.53 ± 0.13 m/s for MB2_GRAPPA2. ICC revealed excellent absolute agreement and consistency of total flow for all methods compared to SB2. Peak velocity showed good to excellent agreement and consistency for SumSB and MB2 and MB2_GRAPPA2 method showed poor to excellent agreement and good to excellent consistency.
Simultaneous multislab 4D Flow MRI allows accurate quantification of total flow and peak velocity while reducing scan times.
开发并在7T场强下实施同步多层面（SMSb）4D血流MRI技术，以加速获取双侧颈动脉分叉处的三维血流速度矢量场。
将SMSb应用于4D血流成像，使用7T场强下的局部发射/接收线圈，以矢状位获取双侧颈动脉分叉处的血流速度。通过匀场优化发射效率。对8名健康受试者以单带（SB）和多带（MB）方式获取SMSb 4D血流数据。此外，对MB数据进行回顾性欠采样以模拟GRAPPA加速因子R = 2（MB2_GRAPPA2），并将两个SB数据集相加形成人工MB数据集（SumSB）。通过信号泄漏量化带分离性能。计算峰值速度和总流量值，并通过组内相关分析（ICC）与SB进行比较。
实现了清晰的层面分离，平均信号泄漏比SB平均噪声水平高13%。MB2、SumSB和MB_GRAPPA2的平均总流量与SB值的偏差小于9%。所有血管和受试者的平均峰值速度，SB为0.48±0.11 m/s，SumSB为0.47±0.12 m/s，MB²为0.50±0.13 m/s，MB2_GRAPPA2为0.53±0.13 m/s。ICC显示，与SB2相比，所有方法的总流量具有极好的绝对一致性。SumSB以及MB2和MB2_GRAPPA2方法的峰值速度显示出良好到极好的一致性，而MB2_GRAPPA2方法的峰值速度显示出较差到极好的一致性。
同步多层面4D血流MRI在减少扫描时间的同时，能够准确量化总流量和峰值速度。
