Journal: iScience

Article Title: Perivascular cerebrospinal fluid inflow matches interstitial fluid efflux in anesthetized rats

doi: 10.1016/j.isci.2025.112323

Figure Lengend Snippet: Dynamic contrast-enhanced MRI allows quantification of CSF flow velocity in pial perivascular spaces ( | v → PVS | ) (A) MRI was used to track the flow of a small paramagnetic tracer (Gd-DTPA) in CSF. (B) After infusion in cisterna magna, glymphatic flow carried the tracer to the brain tissue via pial PVSs of major cerebral arteries. Scale bar: 5 mm. (C) High-resolution T2-weighted images show parallel CSF-filled subarachnoid channels that served as conduits for the CSF flow. Scale bar: 5 mm, 2 mm in inserts. (D) The front of the tracer wave arrived at the MCA ∼20 min after the infusion started and covered the length of the trunk in ∼10 min. Scale bar: 5 mm, 2 mm in inserts. (E) We measured time-concentration-curves along the MCA and estimated the flow velocity as the slope of the linear fit of distance along the MCA and the time to exceed 20% of peak tracer concentration. (F) Resulting flow velocity | v → PVS | ( n = 8). We replicated the experiment using a larger tracer molecule and smaller infusion volume ( n = 5, GadospinP, 200 kDa, 10 μL, 2 μL/min) with very similar results. Abbreviations: CSF, cerebrospinal fluid; MCA, middle cerebral artery; MRI, magnetic resonance imaging. Data are represented as mean + standard deviation (STD).

Article Snippet: To investigate the flow of CSF to brain parenchyma, we used T2-weighted (T2w) and quantitative dynamic contrast-enhanced MRI (DCE-MRI) to measure the flow of a small paramagnetic tracer, gadopentetic acid (Gd-DTPA, 0.5 kDa; BioPAL, MA, USA) after infusion in the CSF in cisterna magna (12.5 mM, 40 μL, 2 μL min −1 ) in healthy rats ( n = 8, 200–300 g) anesthetized with ketamine-dexmedetomidine ( A).

Techniques: Concentration Assay, Magnetic Resonance Imaging, Standard Deviation