Identifying Significant Changes in Cerebrovascular Reactivity to Carbon Dioxide

Area of Science:

• Neuroimaging
• Vascular Neurology
• Medical Imaging Analysis

Background:

• Cerebrovascular reactivity (CVR) assessment is crucial for monitoring disease progression and therapy response.
• Distinguishing true pathological changes from normal test-to-test variability is essential.
• Variability in CVR testing arises from methodology, technology, and physiological fluctuations over time.

Purpose of the Study:

• To quantify the test-to-test variability of cerebrovascular reactivity in healthy subjects.
• To establish a reference atlas for cerebrovascular reactivity interval differences.
• To assess the feasibility of identifying significant changes in patients with cerebrovascular disease.

Main Methods:

• Two standardized 3T MRI-based CVR tests were performed on healthy subjects and patients with cerebrovascular disease.
• Cerebrovascular reactivity was calculated as the ratio of BOLD MR imaging response to CO2 stimulus change.
• Test-retest differences were coregistered, analyzed voxelwise, and visualized as z-maps for statistical scoring.

Main Results:

• No significant test-to-test differences in cerebrovascular reactivity were observed in gray or white matter of healthy subjects.
• Patient cerebrovascular reactivity interval difference z-maps effectively highlighted regions with significant increases or decreases in CVR.
• The developed atlas provided a statistical framework for interpreting individual patient changes.

Conclusions:

• Establishing normal test-to-test variability is critical for accurate CVR assessment.
• This method allows for reliable detection of significant changes in cerebrovascular disease status over time.
• The findings support the use of CVR variability analysis for monitoring disease stability, progression, or regression.