Bito Yoshitaka, Ochi Hisaaki, Shirase Ryuji, Yokohama Wataru, Harada Kuniaki, Kudo Kohsuke
FUJIFILM Healthcare Corporation.
Department of Diagnostic Imaging, Hokkaido University Graduate School of Medicine.
Magn Reson Med Sci. 2025 Jan 1;24(1):46-57. doi: 10.2463/mrms.mp.2023-0081. Epub 2023 Oct 27.
Analysis of cerebrospinal fluid (CSF) dynamics may be beneficial for understanding the mechanisms and diagnosis of several neurological diseases. Low b-value diffusion tensor imaging (low-b DTI) is useful for observing the slow and complex motion of the CSF. Theoretically, a mathematical framework suggests that low-b DTI provides the variance of the pseudorandom motion of the CSF. Furthermore, low-b DTI could provide comprehensive information on fluid dynamics. Accordingly, we proposed an analysis technique that resolves intravoxel pseudorandom motion into ordered (linear) and disordered (random) motions based on the mathematical framework.
The proposed analysis technique helps measure low-b DTI with multiple diffusion times and linearly fits its mean diffusivity (MD) with the diffusion time to obtain two parameters, double-slope V and y-intersect D, which represent the variance of the velocity distribution of linear motion and the diffusion coefficient of random motion, respectively. Seven healthy subjects were scanned to evaluate the proposed technique and investigate fluid dynamics in several representative ROIs.
The obtained data showed the validity of the technique, repeatability, and consistency across the subjects in ROIs, such as the lateral ventricle (LV), third ventricle (3V), fourth ventricle (4V), and Sylvian fissure (SF). The obtained parameters V and D highlighted different characteristics of fluid dynamics in the representative ROIs: low V and low D in the LV, high V and moderate D in the 3V, and moderate V and moderate D in the 4V and SF.
The proposed analysis technique will facilitate a comprehensive investigation of the complex dynamics of the CSF using resolved parameters representing ordered and disordered motions.
分析脑脊液（CSF）动力学可能有助于理解几种神经系统疾病的发病机制和诊断。低b值扩散张量成像（低b值DTI）有助于观察脑脊液的缓慢且复杂的运动。从理论上讲，一个数学框架表明低b值DTI提供了脑脊液伪随机运动的方差。此外，低b值DTI可以提供有关流体动力学的全面信息。因此，我们基于该数学框架提出了一种分析技术，该技术将体素内伪随机运动分解为有序（线性）和无序（随机）运动。
所提出的分析技术有助于在多个扩散时间测量低b值DTI，并将其平均扩散率（MD）与扩散时间进行线性拟合，以获得两个参数，即双斜率V和y轴截距D，它们分别代表线性运动速度分布的方差和随机运动的扩散系数。对7名健康受试者进行扫描，以评估所提出的技术并研究几个代表性感兴趣区域（ROI）中的流体动力学。
获得的数据显示了该技术的有效性、可重复性以及在诸如侧脑室（LV）、第三脑室（3V）、第四脑室（4V）和大脑外侧裂（SF）等ROI中受试者之间的一致性。获得的参数V和D突出了代表性ROI中流体动力学的不同特征：LV中的V低且D低，3V中的V高且D中等，4V和SF中的V中等且D中等。
所提出的分析技术将有助于使用代表有序和无序运动的分解参数对脑脊液的复杂动力学进行全面研究。
