BOLD-CSF dynamics assessed using real-time phase contrast CSF flow interleaved with cortical BOLD MRI.

Area of Science:

• Neuroimaging
• Cerebrospinal Fluid Dynamics
• Brain Waste Clearance

Background:

• Cerebrospinal fluid (CSF) pulsatility is linked to brain waste clearance, potentially driven by vasomotion.
• Existing methods like BOLD fMRI lack quantitative, bidirectional CSF flow data and are sensitive to magnetic field fluctuations.
• Real-time phase contrast (pcCSF) offers quantitative, bidirectional CSF flow but lacks hemodynamic information.

Purpose of the Study:

• To develop and validate a novel interleaved MRI technique combining pcCSF and cortical BOLD.
• To enable quantitative assessment of the interaction between CSF flow and cortical hemodynamic oscillations.

Main Methods:

• Two experiments were conducted comparing pcCSF and inflow-sensitive BOLD (iCSF) measurements.
• The novel interleaved pcCSF and cortical BOLD sequence was compared to the original iCSF technique for BOLD-CSF coupling analysis.
• Participants performed paced breathing to synchronize CSF fluctuations.

Main Results:

• pcCSF demonstrated more pronounced bidirectional CSF in- and outflow compared to iCSF.
• The novel pcCSF-BOLD method revealed stronger BOLD-CSF coupling (mean increase 0.22, p=0.008).
• A significantly shorter temporal lag (1.9 s, p=0.016) was observed with the pcCSF-BOLD method.

Conclusions:

• A new method for studying CSF flow (fourth ventricle) and cortical BOLD coupling is presented.
• Phase contrast MRI for CSF flow measurement provides quantitative in- and outflow data.
• The novel method improves BOLD-CSF coupling metrics compared to previous techniques.