Non-invasive MR imaging of human brain lymphatic networks with connections to cervical lymph nodes

Meningeal lymphatic vessels have been described in animal studies, but limited comparable data is available in human studies. Here we show dural lymphatic structures along the dural venous sinuses in dorsal regions and along cranial nerves in the ventral regions in the human brain. 3D T2-Fluid Attenuated Inversion Recovery magnetic resonance imaging relies on internal signals of protein rich lymphatic fluid rather than contrast media and is used in the present study to visualize the major human dural lymphatic structures. Moreover we detect direct connections between lymphatic fluid channels along the cranial nerves and vascular structures and the cervical lymph nodes. We also identify age-related cervical lymph node atrophy and thickening of lymphatics channels in both dorsal and ventral regions, findings which reflect the reduced lymphatic output of the aged brain. Studies in animal models have visualized drainage of interstitial or cerebrospinal fluid via lymphatic vessels, but there is limited data on in humans. Here, the authors non-invasively visualize lymphatic structures in the human brain, including evidence of lymphatic flow from cranial nerves to cervical lymph nodes, and differences by age and sex, without use of contrast agents.

Automated summary

This study non-invasively visualizes lymphatic structures in the human brain, showing evidence of lymphatic flow from cranial nerves to cervical lymph nodes, as well as differences by age and sex.