Respiration Can Trigger Cerebrovascular Reactivity: A New Method to Quantify Respiratory-Driven CVR Using Real-time phase contrast MRI

Motivation: Quantifying cerebrovascular reactivity (CVR) is key for diagnosing and understanding neurological diseases. However, measuring respiratory-driven CVR is challenging due to the difficulty in separating cardiac effects from CVR modulation. Goal(s): Propose a novel approach to accurately quantify respiratory-driven CVR. Approach: Using real-time phase-contrast sequences and respiratory signals to quantify respiratory-driven CVR by analysing the flow ratio (Ratio-Q) between the internal and external carotid arteries. Results: Sustained deep breathing increases cerebrovascular resistance causing a 20% reduction in average carotid artery flow and Ratio-Q. CVR also regulates cerebrovascular resistance at the respiratory frequency, stabilizing cerebral blood flow fluctuations. Impact: This study introduces a new, effective method for measuring respiratory-driven CVR, comparing results across two different breathing modes. It provides crucial methodological support and reference data for clinical and physiological research.