Measuring global cerebrovascular pulsatility transmission using 4D flow MRI.

Area of Science:

• Neurology
• Biomedical Engineering
• Cardiovascular Physiology

Background:

• Pulse wave encephalopathy (PWE) is a hypothesized driver of dementia, necessitating better risk identification tools.
• Current pulsatility biomarkers (pulsatility index, damping) lack accuracy due to variability and spatial bias.
• Accurate assessment of cerebrovascular pulsatility is crucial for understanding PWE and dementia risk.

Purpose of the Study:

• To introduce a novel, locus-independent pulsatility transmission coefficient for characterizing whole-brain pulse dynamics.
• To evaluate this new coefficient as a potential biomarker for PWE risk assessment.
• To explore regional differences in cerebral pulsatility and their underlying causes.

Main Methods:

• Development of a pulsatility transmission coefficient calculated by spatially tracking pulsatility along cerebral vessels.
• Application of the method to a cohort of 20 subjects for preliminary analysis.
• Comparison of the new coefficient with clinical factors like age, heart rate, and sex.

Main Results:

• The pulsatility transmission coefficient showed agreement with established relationships between blood pulsatility, age, heart rate, and sex.
• Identified distinct pulsatility transmission patterns between vascular territories supplied by the basilar and internal carotid arteries, linked to cerebral blood flow.
• Observed inter-individual differences in internal carotid territories not explained by flow or pulsatility, suggesting intrinsic vascular mechanical variations.

Conclusions:

• The pulsatility transmission coefficient is a promising candidate biomarker for PWE risk assessment.
• This whole-organ approach provides a comprehensive hemodynamic description of the brain's arterial system.
• Future large-scale studies can leverage this method for retrospective analysis, advancing our understanding of brain hemodynamics and dementia risk.