Limits to flow detection in phase contrast MRI.
Limits to flow detection in phase contrast MRI.
复制标题
相衬 MRI 中血流检测的限制。
DOI：
10.1016/j.jmro.2020.100004
复制
发表时间：
2020
影响因子：
--
通讯作者：
Basser,PeterJ
中科院分区：
文献类型：
--
作者：
Williamson,NathanH;Komlosh,MichalE;Benjamini,Dan;Basser,PeterJ
当流动引起的位移与扩散位移相似或小于扩散位移时，脉冲梯度自旋回波（PGSE）复合信号行为将由衰减而不是振荡主导。在这种“慢流”状态下，用于相衬速度测量的最佳位移编码参数q取决于扩散长度尺度q s l o w= 1/l D= 1/2 D Δ，而不是速度编码参数v e n c= π/（q Δ）。使用+ q s l o w和− q s l o w处的相位差，可检测的最小平均速度为< v min>= 1/SNR D/Δ。这些理论，然后验证和应用到MRI通过执行PGSE回波平面成像实验的水流过一个列与散装区域和beadpack区域在控制流速。测速仪检测到的速度低至6 μm/s。理论、MRI实验方案和受控体模上的验证有助于弥合多孔介质NMR与临床前相位对比和扩散MRI之间的差距。
Pulsed gradient spin echo (PGSE) complex signal behavior becomes dominated by attenuation rather than oscillation when displacements due to flow are similar or less than diffusive displacements. In this “slow-flow” regime, the optimal displacement encoding parameter q for phase contrast velocimetry depends on the diffusive length scale q s l o w= 1/l D= 1/2 D Δ rather than the velocity encoding parameter v e n c= π/(q Δ). The minimum detectable mean velocity using the difference between the phase at+ q s l o w and− q s l o w is< v min>= 1/SNR D/Δ. These theories are then validated and applied to MRI by performing PGSE echo planar imaging experiments on water flowing through a column with a bulk region and a beadpack region at controlled flow rates. Velocities as slow as 6 μm/s are detected with velocimetry. Theories, MRI experimental protocols, and validation on a controlled phantom help to bridge the gap between porous media NMR and pre-clinical phase contrast and diffusion MRI.