Cardiac-Related Pulsatility in the Insula Is Directly Associated With Middle Cerebral Artery Pulsatility Index

Abstract

Background: Arterial stiffness in large arteries is a risk factor for cerebral small vessel disease and neurodegeneration. The challenge of accessing intracranial pulsatility noninvasively is one reason few studies provide empirical insight on the relationship between large artery and tissue pulsatility in the human brain.

Purpose: To investigate the association between the functional magnetic resonance imaging (fMRI)-derived cardiac-related pulsatility in the insular cortex and the ultrasound-derived pulsatility index in the middle cerebral artery (MCA-PI).

Study type: Cross-sectional.

Population: Younger adults (11; 25 ± 4 years) and older adults with and without cardiovascular risk factors (44; 70 ± 6 years).

Field strength/sequence: T₁ -weighted, fluid attenuated inversion recovery, and T₂ *-weighted blood oxygenation level-dependent (BOLD) sequences at 3T.

Assessment: MCA-PI and cardiac-related pulsatility were assessed at rest by transcranial Doppler ultrasound and BOLD fMRI, respectively.

Statistical tests: Multivariate analyses of covariance between MCA-PI and cardiac-related pulsatility. Analysis of variance was used to assess regional differences.

Results: MCA-PI was associated with cardiac-related insular pulsatility (P = 0.037), but not whole-brain pulsatility (P = 0.81). Left insular pulsatility was higher than right insular pulsatility (P < 0.01) and was associated with diastolic blood pressure (P = 0.028).

Data conclusion: We show a correlation between ultrasound and fMRI measures of cerebrovascular pulsatility. This association provides insight into the transmission of pulsatile energy from large basal arteries at the Circle of Willis to downstream cerebrovascular beds and has implications for the utility of cardiac-related pulsatility as a potential marker for cerebral small vessel disease.

Level of evidence: 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;51:1454-1462.

Keywords: arterial stiffness; blood oxygenation level dependent contrast; cerebrovascular pulsatility; functional magnetic resonance imaging; transcranial Doppler ultrasound.