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Real‐time imaging of respiratory effects on cerebrospinal fluid flow in small diameter passageways
Author(s) -
Töger Johannes,
Andersen Mads,
Haglund Olle,
Kylkilahti Tekla Maria,
Lundgaard Iben,
Markenroth Bloch Karin
Publication year - 2022
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.29248
Subject(s) - repeatability , intraclass correlation , imaging phantom , temporal resolution , respiratory system , image resolution , biomedical engineering , correlation coefficient , magnetic resonance imaging , scanner , flow (mathematics) , nuclear magnetic resonance , nuclear medicine , materials science , reproducibility , physics , mathematics , chemistry , medicine , anatomy , mechanics , radiology , optics , chromatography , statistics
Purpose Respiration‐related CSF flow through the cerebral aqueduct may be useful for elucidating physiology and pathophysiology of the glymphatic system, which has been proposed as a mechanism of brain waste clearance. Therefore, we aimed to (1) develop a real‐time (CSF) flow imaging method with high spatial and sufficient temporal resolution to capture respiratory effects, (2) validate the method in a phantom setup and numerical simulations, and (3) apply the method in vivo and quantify its repeatability and correlation with different respiratory conditions. Methods A golden‐angle radial flow sequence (reconstructed temporal resolution 168 ms, spatial resolution 0.6 mm) was implemented on a 7T MRI scanner and reconstructed using compressed sensing. A phantom setup mimicked simultaneous cardiac and respiratory flow oscillations. The effect of temporal resolution and vessel diameter was investigated numerically. Healthy volunteers ( n = 10) were scanned at four different respiratory conditions, including repeat scans. Results Phantom data show that the developed sequence accurately quantifies respiratory oscillations (ratio real‐time/reference Q R = 0.96 ± 0.02), but underestimates the rapid cardiac oscillations (ratio Q C = 0.46 ± 0.14). Simulations suggest that Q C can be improved by increasing temporal resolution. In vivo repeatability was moderate to very strong for cranial and caudal flow (intraclass correlation coefficient range: 0.55–0.99) and weak to strong for net flow (intraclass correlation coefficient range: 0.48–0.90). Net flow was influenced by respiratory condition ( p < 0.01). Conclusions The presented real‐time flow MRI method can quantify respiratory‐related variations of CSF flow in the cerebral aqueduct, but it underestimates rapid cardiac oscillations. In vivo, the method showed good repeatability and a relationship between flow and respiration.