MRI‐based assessment of acute effect of head‐down tilt position on intracranial hemodynamics and hydrodynamics

Ishida, Shota; Miyati, Tosiaki; Ohno, Naoki; Hiratsuka, Shinnosuke; Alperin, Noam; Mase, Mitsuhito; Gabata, Toshifumi

doi:10.1002/jmri.25781

Cited by 21 publications

(37 citation statements)

References 29 publications

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“…There was also a decrease in SV, but it did not reach statistical significance. arterial inflow, increases in venous outflow, and no significant changes in CSF stroke volume or systolic velocity [12]. These observed changes in venous CSA under ground-based HDT are consistent with ultrasound studies performed during spaceflight that demonstrate comparable increases in venous CSA in subjects exposed to microgravity [23,24].…”

Section: Resultssupporting

confidence: 86%

“…Head-down tilt (HDT) has been used to simulate microgravity in ground-based studies that seek to quantify changes in arterial and venous flow dynamics. However, prior studies have yielded conflicting results about arterial blood flow dynamics [11,12] and have not comprehensively studied CSF flow dynamics, which is an important underlying aspect of the "fluids shift" hypothesis for SANS [8].…”

mentioning

confidence: 99%

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Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

Zahid

Martin

Collins

et al. 2020

Preprint

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Background: Astronauts undergoing long-duration spaceflight are exposed to numerous health risks, including Spaceflight-Associated Neuro-Ocular Syndrome (SANS), a spectrum of ophthalmic changes that can result in permanent loss of visual acuity. The etiology of SANS is not well understood but is thought to involve changes in cerebrovascular flow dynamics in response to microgravity. There is a paucity of knowledge in this area; in particular, cerebrospinal fluid (CSF) flow dynamics have not been well characterized under microgravity conditions. Our study was designed to determine the effect of simulated microgravity (head-down tilt [HDT]) on cerebrovascular flow dynamics. We hypothesized that under microgravity conditions simulated by HDT, increased pressure in the intracranial space would alter intracranial CSF and venous flow dynamics by causing: 1) venous congestion reflected by increased venous cross-sectional area; and 2) a decrease in cardiac-related CSF flow oscillations. Methods: In a prospective cohort study, we measured flow in major cerebral arteries, veins, and CSF spaces in fifteen healthy volunteers using phase contrast magnetic resonance (PCMR) before and during 15° HDT. Results: We found a significant increase in venous cross-sectional area with HDT (p=0.005), indicating venous congestion, along with a decrease in all CSF flow parameters [systolic peak flow (p=0.009), peak-to-peak pulse amplitude (p=0.001), and stroke volume (p=0.10)]. Arterial average flow (p=0.04), systolic peak flow (p=0.04), and peak-to-peak pulse amplitude (p=0.02) all also significantly decreased. Conclusions: These results collectively demonstrate that acute application of 15° HDT caused a reduction in CSF flow parameters (systolic peak flow and peak-to-peak pulse amplitude), coupled with an increase in venous CSA suggesting increased venous congestion with HDT.

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Section: Resultssupporting

confidence: 86%

mentioning

confidence: 99%

Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

Zahid

Martin

Collins

et al. 2020

Preprint

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“…A study using a 15° HDT protocol to assess venous jugular blood ow before, during, and after space ight on International Space Station crew members demonstrated that venous CSA increased from sitting to supine to HDT with a similar magnitude of change between those positions pre ight and post ight, although HDT in both of those settings overestimated increases in venous CSA found in-ight [32]. However, our venous and arterial changes from baseline to 15° HDT are corroborated by prior studies at these lower degrees of HDT, which lends support to the validity of our CSF ndings at 15° [10,11,36].…”

Section: Discussionsupporting

confidence: 86%

“…Ishida et al, using 15 healthy volunteers, found increases in venous CSA (36 mm 2 to 54 mm 2 ), decreases in arterial in ow, increases in venous out ow, and no signi cant changes in CSF stroke volume or systolic velocity [11]. These observed changes in venous CSA under ground-based HDT are consistent with ultrasound studies performed during space ight that demonstrate comparable increases in venous CSA in subjects exposed to microgravity, which lends validity to the results of these HDT protocols [23,24].…”

Section: Discussionmentioning

confidence: 96%

“…Head-down tilt (HDT) has been used to simulate microgravity in ground-based studies that seek to quantify changes in arterial and venous ow dynamics [9]. However, prior studies have yielded con icting results about arterial blood ow dynamics [10,11] and have not comprehensively studied CSF ow dynamics, which is an important underlying aspect of the " uids shift" hypothesis for SANS [6].…”

Section: Introductionmentioning

confidence: 99%

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Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

Zahid

Martin

Collins

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract Background: Astronauts undergoing long-duration spaceflight are exposed to numerous health risks, including Spaceflight-Associated Neuro-Ocular Syndrome (SANS), a spectrum of ophthalmic changes that can result in permanent loss of visual acuity. The etiology of SANS is not well understood but is thought to involve changes in cerebrovascular flow dynamics in response to microgravity. There is a paucity of knowledge in this area; in particular, cerebrospinal fluid (CSF) flow dynamics have not been well characterized under microgravity conditions. Our study was designed to determine the effect of simulated microgravity (head-down tilt [HDT]) on cerebrovascular flow dynamics. We hypothesized that under microgravity conditions simulated by HDT, increased pressure in the intracranial space would alter intracranial CSF and venous flow dynamics by causing: 1) increased venous pressure reflected by increased venous cross-sectional area; and 2) a decrease in cardiac-related pulsatile CSF flow.Methods: In a prospective cohort study, we measured flow in major cerebral arteries, veins, and CSF spaces in fifteen healthy volunteers using phase contrast magnetic resonance (PCMR) before and during 15° HDT.Results: We found a significant increase in venous cross-sectional area with HDT (p=0.005), indicating increased venous pressure, along with a decrease in all CSF flow variables [systolic peak flow (p=0.009), and peak-to-peak pulse amplitude (p=0.001)]. Arterial average flow (p=0.04), systolic peak flow (p=0.04), and peak-to-peak pulse amplitude (p=0.02) all also significantly decreased.Conclusions: These results collectively demonstrate that acute application of 15° HDT caused a reduction in CSF flow variables (systolic peak flow and peak-to-peak pulse amplitude), coupled with an increase in venous CSA suggesting increased venous pressure with HDT.

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Impact of Head‐Down Position on Cerebral Blood Flow in Healthy Subjects: An Arterial Spin‐Labeling MR Perfusion Study

Mejdoubi

Pavilla

Colombani

et al. 2019

Magnetic Resonance Imaging

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Background: A head-down (HD) position is used in some stroke centers to maintain cerebral perfusion (CP) in stroke patients. Purpose: To assess CP in healthy volunteers in the supine and HD (-15 ) positions. Study Type: Prospective. Population: Eighteen healthy subjects of 53 (AE8) years old. Field Strength/Sequence: 1.5T / arterial spin-labeling (ASL) in the supine position and after 4 minutes of HD position. Assessment: Regions of interest from reconstructed cerebral blood-flow (CBF) maps: subcortical nuclear gray matter (accumbens, amygdala, caudate, hippocampus, pallidum, putamen, thalamus), cortical gray matter (cGM), and white matter (WM). We also monitored hemodynamic parameters. Statistical Tests: Shapiro-Wilk test, analysis of variance (ANOVA) tests, Student's t-tests, and Pearson correlation analysis. Results: CBF was higher in women compared to men, whatever the position (mean difference of 17% in supine, and 13% in HD position). From supine to HD position, CBF was decreased in all regions (mean decrease of -7%). Simultaneously, mean arterial pressure and systolic blood pressure increased (respectively P = 0.004 and P < 0.001). Data Conclusion: The CBF decrease, despite increased hemodynamic parameters, may indicate efficient cerebral autoregulation. Our results seem to reflect only early cerebral autoregulation stages but may open the way towards a more precise understanding of CP. Level of Evidence: 1 Technical Efficacy: Stage 2

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MRI‐based assessment of acute effect of head‐down tilt position on intracranial hemodynamics and hydrodynamics

Abstract: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:565-571.

Cited by 21 publications

References 29 publications

Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

Quantification of Arterial, Venous, and Cerebrospinal Fluid Flow Dynamics by Magnetic Resonance Imaging Under Simulated Micro-Gravity Conditions: A Prospective Cohort Study

Impact of Head‐Down Position on Cerebral Blood Flow in Healthy Subjects: An Arterial Spin‐Labeling MR Perfusion Study

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