Investigation of the pulsatility of cerebrospinal fluid using cardiac-gated Intravoxel Incoherent Motion imaging
Investigation of the pulsatility of cerebrospinal fluid using cardiac-gated Intravoxel Incoherent Motion imaging
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DOI：
10.1016/j.neuroimage.2017.12.017
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发表时间：
2018-04-01
期刊：
影响因子：
5.7
通讯作者：
Rossi, Cristina
中科院分区：
文献类型：
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作者：
Becker, Anton S.;Boss, Andreas;Rossi, Cristina
脑脊液(CSF)动力学和成分的定量和非侵入性监测在脑脊液疾病的治疗中具有很高的临床意义。在这项研究中，我们建议使用体素内非相干运动(IVIM)MRI来同时测量脑脊液的自我扩散和液体循环。这项研究的基本原理是，湍流和介观流体波动可以在一次近似中模拟为快速扩散过程。在这种情况下，我们预计快速流体循环和较慢的分子扩散动力学可以被量化，假设磁共振扩散加权信号的双指数衰减模式。IVIM指数的快速和缓慢扩散测量在脑脊液系统的不同位置被系统地评估取决于心脏周期的阶段和扩散编码的方向。将IVIM测量结果与相衬MRI进行的流体循环动态测量结果进行了比较。考虑到扩散/流动编码方向的依赖关系，在快速扩散分数f和流体速度上都发现了相似的模式。总的来说，我们观察到沿高流动方向的快速扩散分数与最大流体速度之间存在中等到高度的相关性。探索性数据分析发现，心动周期各阶段的快速扩散分数和速度的依赖关系相似。然而，在心脏周期的不同阶段测量的参数之间没有显著差异。我们的结果表明，快速弥散分数可能反映了脑脊液循环。双指数IVIM模型通过提供液体细胞密度(通过慢扩散系数)和循环(通过快扩散指数的分数)的测量，潜在地使我们能够分离脑脊液动力学的两个扩散成分。
The quantitative and non-invasive monitoring of cerebrospinal fluid (CSF) dynamics and composition may have high clinical relevance in the management of CSF disorders. In this study, we propose the use of the Intravoxel Incoherent Motion (IVIM) MRI for obtaining simultaneous measurements of CSF self-diffusion and fluid circulation. The rationale for this study was that turbulent fluid and mesoscopic fluid fluctuations can be modeled in a first approximation as a fast diffusion process. In this case, we expect that the fast fluid circulation and slower molecular diffusion dynamics can be quantified, assuming a bi-exponential attenuation pattern of the diffusionweighted signal in MRI.IVIM indexes of fast and slow diffusion measured at different sites of the CSF system were systematically evaluated depending on both the phase of the heart cycle and the direction of the diffusion-encoding. The IVIM measurements were compared to dynamic measurements of fluid circulation performed by phase-contrast MRI.Concerning the dependence on the diffusion/flow-encoding direction, similar patterns were found both in the fraction of fast diffusion, f, and in the fluid velocity. Generally, we observed a moderate to high correlation between the fraction of fast diffusion and the maximum fluid velocity along the high-flow directions. Exploratory data analysis detected similarities in the dependency of the fraction of fast diffusion and of the velocity from the phase of the cardiac cycle. However, no significant differences were found between parameters measured during different phases of the cardiac cycle.Our results suggest that the fraction of fast diffusion may reflect CSF circulation. The bi-exponential IVIM model potentially allows us to disentangle the two diffusion components of the CSF dynamics by providing measurements of fluid cellularity (via the slow-diffusion coefficient) and circulation (via the fraction of fastdiffusion index).