Lee Min Kyoung, Cho Se Jin, Bae Yun Jung, Kim Jong-Min
Department of Radiology, College of Medicine, Yeouido St. Mary's Hospital, The Catholic University of Korea, Soeul, South Korea.
Department of Radiology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea.
Front Neurol. 2022 May 25;13:827398. doi: 10.3389/fneur.2022.827398. eCollection 2022.
The glymphatic system has been described as one that facilitates the exchange between the cerebrospinal fluid (CSF) and interstitial fluid, and many recent studies have demonstrated glymphatic flow based on magnetic resonance imaging (MRI). We aim to systematically review the studies demonstrating a normal glymphatic flow in a human population using MRI and to propose a detailed glymphatic imaging protocol.
We searched the MEDLINE and EMBASE databases to identify studies with human participants involving MRI-based demonstrations of the normal glymphatic flow. We extracted data on the imaging sequence, imaging protocol, and the targeted anatomical structures on each study.
According to contrast-enhanced MRI studies, peak enhancement was sequentially detected first in the CSF space, followed by the brain parenchyma, the meningeal lymphatic vessel (MLV), and, finally, the cervical lymph nodes, corresponding with glymphatic flow and explaining the drainage into the MLV. Non-contrast flow-sensitive MRI studies revealed similar glymphatic inflow from the CSF space to the brain parenchyma and efflux of exchanged fluid from the brain parenchyma to the MLV.
We may recommend T1-weighted contrast-enhanced MRI for visualizing glymphatic flow. Our result can increase understanding of the glymphatic system and may lay the groundwork for establishing central nervous system fluid dynamic theories and developing standardized imaging protocols.
淋巴系统被描述为促进脑脊液（CSF）与组织间液交换的系统，最近许多研究已通过磁共振成像（MRI）证实了淋巴液流动。我们旨在系统回顾使用MRI在人群中证实正常淋巴液流动的研究，并提出详细的淋巴成像方案。
我们检索了MEDLINE和EMBASE数据库，以识别涉及基于MRI对正常淋巴液流动进行演示的人体研究。我们提取了每项研究中关于成像序列、成像方案和目标解剖结构的数据。
根据对比增强MRI研究，首先在脑脊液空间依次检测到峰值增强，随后是脑实质、脑膜淋巴管（MLV），最后是颈部淋巴结，这与淋巴液流动一致，并解释了其向MLV的引流。非对比流动敏感MRI研究显示，从脑脊液空间到脑实质有类似的淋巴液流入，以及交换后的液体从脑实质到MLV的流出。
我们可能推荐使用T1加权对比增强MRI来观察淋巴液流动。我们的结果可以增进对淋巴系统的理解，并可能为建立中枢神经系统流体动力学理论和制定标准化成像方案奠定基础。
