Cited by 293Cerebrospinal fluid and hydrocephalusCerebral Venous Sinus ThrombosisNeurosurgical Procedures and Complications

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Cerebrospinal fluid tracer efflux to parasagittal dura in humans

Open access
Ringstad, Geir, Eide, Per Kristian·2020·Nature Communications

Abstract

The mechanisms behind molecular transport from cerebrospinal fluid to dural lymphatic vessels remain unknown. This study utilized magnetic resonance imaging along with cerebrospinal fluid tracer to visualize clearance pathways to human dural lymphatics in vivo. In 18 subjects with suspicion of various types of cerebrospinal fluid disorders, 3D T2-Fluid Attenuated Inversion Recovery, T1-black-blood, and T1 gradient echo acquisitions were obtained prior to intrathecal administration of the contrast agent gadobutrol (0.5 ml, 1 mmol/ml), serving as a cerebrospinal fluid tracer. Propagation of tracer was followed with T1 sequences at 3, 6, 24 and 48 h after the injection. The tracer escaped from cerebrospinal fluid into parasagittal dura along the superior sagittal sinus at areas nearby entry of cortical cerebral veins. The findings demonstrate that trans-arachnoid molecular passage does occur and suggest that parasagittal dura may serve as a bridging link between human brain and dural lymphatic vessels.

Overview

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TL;DR

In 18 patients with suspected cerebrospinal fluid (CSF) disorders, intrathecal gadobutrol tracer was followed by MRI for up to 48 h and escaped from CSF into parasagittal dura along the superior sagittal sinus. The findings suggest parasagittal dura may bridge molecular exchange between brain/CSF and dural lymphatic vessels in humans.

Key findings

  • Parasagittal dura was identified in 18/18 patients; after intrathecal gadobutrol, normalized T1-BB signal increased in parasagittal dura at 6, 24, and 48 h, peaking at 24 h (mean percentage change from pre: 156 ± 148 at 6 h, 194 ± 188 at 24 h, 98 ± 79 at 48 h; Table 2).
  • At group level, signal change was highly significant in both parasagittal dura and nearby CSF, was largest within CSF, and signal increases in CSF and parasagittal dura were highly associated (R = 0.92, P < 0.001), with strong positive correlation at all time points.
  • Tracer enhancement below skull base outlets was visually detected below the hypoglossal canal in 17/18, the jugular foramen in 17/18, the cribriform plate in 2/18, and the foramen ovale in 0/18.
  • Tubular structures resembling dural lymphatic vessels could not be discriminated from other enhancing parasagittal dura tissue, possibly related to the 1 × 1 × 1 mm MRI voxel resolution.

Methods

  • Prospective observational study of 18 consecutive individuals referred to neurosurgery for various CSF circulation disorders; no randomization or a priori sample size calculation was used. Exclusion criteria included contrast hypersensitivity, severe allergy, renal dysfunction, age <18 or >80 years, and pregnancy/breastfeeding.
  • Scans were obtained on a 3-Tesla MRI with 3D T2-FLAIR, T1-black-blood, and T1-gradient echo acquisitions; T1-weighted scans were repeated at 3, 6, 24, and 48 h after intrathecal injection of 0.5 ml gadobutrol (1 mmol/ml), preceded by iodixanol to confirm needle position.
  • Regions of interest were placed in parasagittal dura and adjacent subarachnoid CSF on T1-black-blood images, normalized against the ocular bulb vitreous body; differences used linear mixed models with random intercept, correlations used Pearson coefficient, and significance was set at 0.05.

Limitations

  • Stated in the paper: MRI resolution was limited to 1 mm voxel size; lack of T1-mapping techniques restricted measures to semi-quantitative tracer enrichment; the ocular bulb reference may be affected by motion artifacts; and the 48-h multi-phase protocol limited the number of scans per patient, making the peak enhancement time a rough estimate.
  • Evident from the text: the cohort was small (18 patients) and clinically heterogeneous, with no healthy controls; the study could not resolve dural lymphatic vessels directly or quantify the relative importance of parasagittal versus basal outflow pathways.

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Crossref · 10.1038/s41467-019-14195-x

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Figures

Fig. 1 3D representation of parasagittal dura as defined from T2-FLAIR. The brain is shown in oblique coronal view (a) and viewed from above (b). Parasagittal dura (dark yellow) as defined from T2-FLAIR and co-registered with rough segmentation of the brain (gray) and tracer enhancement in CSF (light blue) from T1 GRE at 48 h after intrathecal administration. The CSF tracer propagated toward the upper brain convexities and parasagittal dura at late time points (at 24 h and particularly at 48 h). A video-animation presenting the full longitudinal extension of parasagittal dura is presented in Supplementary Movie 2. Images: Tomas Sakinis, MD.
Fig. 1 3D representation of parasagittal dura as defined from T2-FLAIR. The brain is shown in oblique coronal view (a) and viewed from above (b). Parasagittal dura (dark yellow) as defined from T2-FLAIR and co-registered with rough segmentation of the brain (gray) and tracer enhancement in CSF (light blue) from T1 GRE at 48 h after intrathecal administration. The CSF tracer propagated toward the upper brain convexities and parasagittal dura at late time points (at 24 h and particularly at 48 h). A video-animation presenting the full longitudinal extension of parasagittal dura is presented in Supplementary Movie 2. Images: Tomas Sakinis, MD.CC BY · PubMed Central
Fig. 2 Cerebrospinal fluid (CSF) tracer efflux to parasagittal dura in humans. a Sagittal and coronal T2-FLAIR MR images, respectively, show the typical longitudinal and lateral extension of parasagittal dura (PSD) with high signal (arrows) in one study patient. b Section of coronal T2-FLAIR demonstrates the lateral extension of PSD (arrows). Similar sections (from T1-BB) reveal change in signal intensity of PSD from before (Pre) CSF tracer injection (c), and after 3 h (d), 6 h (e), 24 h (f) and 48 h (g). In h, the PSD is illustrated in yellow color (for more details, see Supplementary Fig. 1; illustration: Øystein Horgmo, University of Oslo). The percentage change in normalized T1-BB signal units in CSF (blue line) and PSD (red line) for the entire cohort of 18 individuals is presented in i. The signal change was highly significant in both locations (linear mixed model analysis; *P < 0.05, **P < 0.01, ***P < 0.001) and was largest within the CSF. Also note that signal change peaked at 24 h in both CSF and PSD, and signal increase in these structures was highly associated (R = 0.92, P < 0.001). Error bars refer to 95% confidence intervals (CI).
Fig. 2 Cerebrospinal fluid (CSF) tracer efflux to parasagittal dura in humans. a Sagittal and coronal T2-FLAIR MR images, respectively, show the typical longitudinal and lateral extension of parasagittal dura (PSD) with high signal (arrows) in one study patient. b Section of coronal T2-FLAIR demonstrates the lateral extension of PSD (arrows). Similar sections (from T1-BB) reveal change in signal intensity of PSD from before (Pre) CSF tracer injection (c), and after 3 h (d), 6 h (e), 24 h (f) and 48 h (g). In h, the PSD is illustrated in yellow color (for more details, see Supplementary Fig. 1; illustration: Øystein Horgmo, University of Oslo). The percentage change in normalized T1-BB signal units in CSF (blue line) and PSD (red line) for the entire cohort of 18 individuals is presented in i. The signal change was highly significant in both locations (linear mixed model analysis; *P < 0.05, **P < 0.01, ***P < 0.001) and was largest within the CSF. Also note that signal change peaked at 24 h in both CSF and PSD, and signal increase in these structures was highly associated (R = 0.92, P < 0.001). Error bars refer to 95% confidence intervals (CI).CC BY · PubMed Central
Fig. 3 Visualization of the parasagittal dura and an arachnoid granulation. The T1-BB images are shown for one individual (no. 8) prior to intrathecal gadobutrol injection (a), and after 3 h (b), 6 h (c) 24 h (d) and 48 h (e). The enrichment of CSF tracer is quantified as change in signal units (SU) within the parasagittal dura, CSF space and within one arachnoid granulation. The regions of interest are marked by an open circle. At 48 h (e), enhancement of the arachnoid granulation could no longer be detected. In f is illustrated the parasagittal dura (PSD, indicated with yellow color) and an arachnoid granulation (AG; illustration: Øystein Horgmo, University of Oslo). In g, the percentage change in normalized T1-BB signal units in CSF (blue line), PSD (red line) and arachnoid granulation (black line) in this individual is presented.
Fig. 3 Visualization of the parasagittal dura and an arachnoid granulation. The T1-BB images are shown for one individual (no. 8) prior to intrathecal gadobutrol injection (a), and after 3 h (b), 6 h (c) 24 h (d) and 48 h (e). The enrichment of CSF tracer is quantified as change in signal units (SU) within the parasagittal dura, CSF space and within one arachnoid granulation. The regions of interest are marked by an open circle. At 48 h (e), enhancement of the arachnoid granulation could no longer be detected. In f is illustrated the parasagittal dura (PSD, indicated with yellow color) and an arachnoid granulation (AG; illustration: Øystein Horgmo, University of Oslo). In g, the percentage change in normalized T1-BB signal units in CSF (blue line), PSD (red line) and arachnoid granulation (black line) in this individual is presented.CC BY · PubMed Central
Fig. 4 Correlations between CSF tracer enhancement in parasagittal dura and nearby CSF space. There was a highly significant positive correlation between CSF tracer enhancement within parasagittal dura and nearby CSF spaces at 3 h (a), 6 h (b), 24 h (c) and 48 h (d). Each plot presents the fit line and the Pearson correlation coefficient (R) with P-value.
Fig. 4 Correlations between CSF tracer enhancement in parasagittal dura and nearby CSF space. There was a highly significant positive correlation between CSF tracer enhancement within parasagittal dura and nearby CSF spaces at 3 h (a), 6 h (b), 24 h (c) and 48 h (d). Each plot presents the fit line and the Pearson correlation coefficient (R) with P-value.CC BY · PubMed Central
Fig. 5 Evidence for CSF efflux along cranial nerves. Posterior (a, b) and anterior (c, d) mid-coronal T1-BB from a patient (no. 10) under work-up for symptoms possibly related to an arachnoid cyst (asterisks in a and b, respectively) at the upper convexity of the right cerebral hemisphere. As compared to 3 h after intrathecal gadobutrol (a), the cyst enhanced homogenously at scans after 24 h (b). Enrichment of parasagittal dura (thick arrows) increased from 3 (a, c) to 24 h (b, d), respectively. CSF tracer within brain perivascular spaces is well illustrated with T1-BB MRI (exemplified as pointed out by arrowheads; d). In addition is shown CSF tracer enhancement below the skull base outlets of the jugular foramen (crosses) and hypoglossal canal (thin arrows) (a, b). In the same patient, there was no sign of tracer enhancement along the mandibular nerve below level of the oval foramen (asterisks) at any time point (c, d).
Fig. 5 Evidence for CSF efflux along cranial nerves. Posterior (a, b) and anterior (c, d) mid-coronal T1-BB from a patient (no. 10) under work-up for symptoms possibly related to an arachnoid cyst (asterisks in a and b, respectively) at the upper convexity of the right cerebral hemisphere. As compared to 3 h after intrathecal gadobutrol (a), the cyst enhanced homogenously at scans after 24 h (b). Enrichment of parasagittal dura (thick arrows) increased from 3 (a, c) to 24 h (b, d), respectively. CSF tracer within brain perivascular spaces is well illustrated with T1-BB MRI (exemplified as pointed out by arrowheads; d). In addition is shown CSF tracer enhancement below the skull base outlets of the jugular foramen (crosses) and hypoglossal canal (thin arrows) (a, b). In the same patient, there was no sign of tracer enhancement along the mandibular nerve below level of the oval foramen (asterisks) at any time point (c, d).CC BY · PubMed Central
Fig. 6 Cartoon illustrating reported microstructural elements within the parasagittal dura based on refs. 14,15. a The parasagittal dura (PSD, colored yellow) contain a network of intradural channels (C, colored light blue), coalescing into lateral lacunae medially (not shown), being in close relation with a dense carpet of intradural arachnoid granulations (AG, orange color). PSD is most prominent at level where the cortical veins (V, dark blue) enter the superior sagittal sinus (SSS, dark blue). Lymphatic vessels (L, green) reside at the SSS wall. The microstructural elements within PSD are of sub-millimeter thickness and therefore not expected to be visualized on MRI with 1 mm resolution. D dura, GM gray matter, SAS subarachnoid space, WM white matter. Illustrations: Øystein Horgmo, University of Oslo.
Fig. 6 Cartoon illustrating reported microstructural elements within the parasagittal dura based on refs. 14,15. a The parasagittal dura (PSD, colored yellow) contain a network of intradural channels (C, colored light blue), coalescing into lateral lacunae medially (not shown), being in close relation with a dense carpet of intradural arachnoid granulations (AG, orange color). PSD is most prominent at level where the cortical veins (V, dark blue) enter the superior sagittal sinus (SSS, dark blue). Lymphatic vessels (L, green) reside at the SSS wall. The microstructural elements within PSD are of sub-millimeter thickness and therefore not expected to be visualized on MRI with 1 mm resolution. D dura, GM gray matter, SAS subarachnoid space, WM white matter. Illustrations: Øystein Horgmo, University of Oslo.CC BY · PubMed Central

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  • The paper relies on this without support.

    The olfactory system is proportionally much lesser in size in humans than in rodents.

    “The olfactory system is indeed of proportionally much lesser size in humans than in rodents”
  • The paper relies on this without support.

    The observed CSF tracer efflux in patients with suspected CSF disorders reflects normal human CSF clearance physiology.

    “The study included 18 patients who were under clinical work-up for possible CSF disorders of various etiologies”
    “In 18 subjects with suspicion of various types of cerebrospinal fluid disorders”
  • The paper relies on this without support.

    T1 signal change in parasagittal dura reflects gadobutrol tracer concentration or enrichment.

    “The CSF tracer enrichment was measured as change in T1-BB signal units, and was normalized against the reference (i.e. the vitreous body of the ocular bulb) to correct for any baseline shift of image grayscale between time points”
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Research works printed but not linked: 1

  1. Cheng, K. T. Gadobutrol. in Molecular Imaging and Contrast Agent Database (MICAD) (National Center for Biotechnology Information, Bethesda, USA, 2004). https://www.ncbi.nlm.nih.gov/pubmed/20641787.

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Metadata

Authors
Ringstad, G., & Eide, P. K.
Affiliations
Oslo University Hospital (NO)
Corresponding author
Eide, Per Kristian
Venue
Nature Communications
Published
2020-01-17
Volume
11
Issue
1
Pages
354-354
ISSN
2041-1723 (ISSN-L)
OpenAlex
W3000117238
Cited by
292
References
23
Citations by year
2026: 42 · 2025: 50 · 2024: 53 · 2023: 54 · 2022: 45 · 2021: 33 · 2020: 15
FWCI
16.85
Type
journal article
Language
en
Open access
Locations
  • Nature Communications (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • NORA - Norwegian Open Research Archives (submittedVersion, cc-by)
Funders
Universitetet i Oslo
Topics
  • Health Sciences › Medicine › Clinical Neurology › Cerebrospinal fluid and hydrocephalus
  • Health Sciences › Medicine › Clinical Neurology › Cerebral Venous Sinus Thrombosis
  • Health Sciences › Medicine › Clinical Neurology › Neurosurgical Procedures and Complications
Keywords
cerebrospinal fluid, superior sagittal sinus, gadobutrol, cerebrospinal fluid clearance, cerebral veins
MeSH terms
Adult, Aged, Arachnoid, Biological Transport, Brain, Cerebrospinal Fluid, Contrast Media, Dura Mater, Humans, Lymphatic System, Magnetic Resonance Imaging, Middle Aged, Organometallic Compounds, Lymphatic Vessels, Young Adult

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