实质血管系统在脑脊髓液示踪剂清除中的作用。
The role of the parenchymal vascular system in cerebrospinal fluid tracer clearance.
机构信息
Department of Radiology, Wayne State University, Detroit, MI, USA.
Department of Neurology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI, 48202, USA.
出版信息
Eur Radiol. 2023 Jan;33(1):656-665. doi: 10.1007/s00330-022-09022-9. Epub 2022 Jul 19.
OBJECTIVES
The current understanding of cerebral waste clearance (CWC) involves cerebrospinal fluid (CSF) participation but lacks convincing evidence for the direct participation of the parenchymal vascular system. The objective of this study was to evaluate the role of the parenchymal vascular system in CSF tracer clearance in rats.
METHODS
We used superparamagnetic iron oxide-enhanced susceptibility-weighted imaging (SPIO-SWI) and quantitative susceptibility mapping (QSM) methods to simultaneously study 7 T MRI signal changes in parenchymal veins, arteries, and their corresponding para-vascular spaces in 26 rats, following intra-cisterna magna (ICM) infusion of different CSF tracers (FeREX, Ferumoxytol, Fe-Dextran) to determine the amount of tracer in the artery and vein quantitatively.
RESULTS
We observed that the parenchymal venous system participated in CSF tracer clearance following ICM infusion of different MRI tracers with different concentrations of iron. Parenchymal venous participation was more obvious when 75 μg iron was injected. In the parenchymal veins, the relative mean (± SE) value of the susceptibility increased by 13.5 (± 1.0)% at 15 min post-tracer infusion (p < 0.01), and 33.6 (± 6.7)% at 45 min post-tracer infusion (p = 0.01), compared to baseline. In contrast to the parenchymal veins, a negligible amount of CSF tracer entered the parenchymal arteries: 1.3 (± 2.6)% at 15 min post-tracer infusion (p = 0.6), and 12 (± 19)% at 45 min post-tracer infusion (p = 0.5), compared to baseline.
CONCLUSIONS
MRI tracers can enter the parenchymal vascular system and more MRI tracers were observed in the cerebral venous than arterial vessels, suggesting the direct participation of parenchymal vascular system in CWC.
KEY POINTS
• MRI results revealed that the parenchymal venous system directly participates in cerebrospinal fluid tracer clearance following ICM infusion of MRI tracer. • Different sizes of MRI tracers can enter the parenchymal venous system.
目的
目前对脑内废物清除（CWC）的认识涉及脑脊液（CSF）的参与，但缺乏对实质脉管系统直接参与的令人信服的证据。本研究的目的是评估实质脉管系统在 CSF 示踪剂清除中的作用。
方法
我们使用超顺磁氧化铁增强的磁敏感加权成像（SPIO-SWI）和定量磁化率映射（QSM）方法，在 26 只大鼠中同时研究了脑室内（ICM）注入不同 CSF 示踪剂（FeREX、Ferumoxytol、Fe-Dextran）后实质静脉、动脉及其相应的血管周围间隙的 7T MRI 信号变化，以定量确定动脉和静脉中的示踪剂量。
结果
我们观察到，在 ICM 注入不同浓度铁的 MRI 示踪剂后，实质静脉系统参与了 CSF 示踪剂的清除。当注入 75μg 铁时，实质静脉的参与更为明显。在实质静脉中，与基线相比，示踪剂注入后 15 分钟（p<0.01）和 45 分钟（p=0.01）时，磁化率的平均（±SE）值增加了 13.5（±1.0）%。与实质静脉相反，很少有 CSF 示踪剂进入实质动脉：与基线相比，示踪剂注入后 15 分钟（p=0.6）和 45 分钟（p=0.5）时，分别为 1.3（±2.6）%和 12（±19）%。
结论
MRI 示踪剂可以进入实质脉管系统，并且在脑静脉中观察到比动脉血管更多的 MRI 示踪剂，这表明实质脉管系统直接参与了 CWC。
关键要点
·MRI 结果显示，在 ICM 注入 MRI 示踪剂后，实质静脉系统直接参与 CSF 示踪剂的清除。·不同大小的 MRI 示踪剂可以进入实质静脉系统。
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