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Published on: February 25, 2022
Intracranial pulse wave velocity using 4D flow MRI: method comparison and covariate analysis
Sergio Dempsey1, Soroush Safaei1, Samantha J Holdsworth2,3
1Auckland Bioengineering Institute, University of Auckland, 70 Symonds Street, Auckland 1010, New Zealand.
Insights
Intracranial pulse wave velocity (PWV) measurement using 4D flow MRI shows that cross-correlation and waveform optimization methods agree well. This study found higher PWV in internal carotids than basilar arteries and no age dependency in healthy individuals.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Cardiovascular Research
Background:
- Intracranial pulse wave velocity (PWV) is a promising biomarker for cerebrovascular disease assessment.
- Current methods for intracranial PWV measurement lack standardized comparison and consensus.
- 4D flow MRI offers a non-invasive approach to evaluate intracranial hemodynamics.
Purpose of the Study:
- To compare three common intracranial PWV measurement techniques: cross-correlation, waveform optimization, and time-to-upstroke.
- To analyze PWV in intracranial vasculature (internal carotids and basilar arteries) in healthy individuals.
- To investigate the relationship between intracranial PWV and age.
Main Methods:
- Utilized 4D flow MRI to measure PWV in the intracranial arteries of 21 healthy adults (age 48 ± 18 years).
- Compared cross-correlation, waveform optimization, and time-to-upstroke methods for PWV calculation.
- Employed an ensemble approach to analyze cohort PWV data, considering methodological variations.
Main Results:
- Cross-correlation and waveform optimization methods demonstrated near-perfect agreement for intracranial PWV.
- The time-to-upstroke method yielded significantly higher PWV values and more non-physiological results.
- Internal carotid arteries exhibited higher PWV (3.64 ± 1.47 m/s) compared to basilar arteries (2.53 ± 1.39 m/s).
- Intracranial PWV was found to be age-independent in the studied cohort.
Conclusions:
- Cross-correlation and waveform optimization are reliable methods for intracranial PWV assessment via 4D flow MRI.
- Higher PWV in internal carotids suggests regional hemodynamic differences within the intracranial circulation.
- The observed age independence of intracranial PWV may represent a protective physiological mechanism against microvascular strain.
- Future research should address potential biases in previous intracranial PWV studies, possibly related to extracranial measurements.
Abstract:
Intracranial pulse wave velocity (PWV) offers the potential to enhance neurovascular care when evaluating cerebrovascular disease. Using 4D flow MRI, we measured PWV in the intracranial vasculature stemming from the internal carotids and basilar arteries using three popular techniques: cross-correlation, waveform optimization and time-to-upstroke which have all been used intracranially, but never compared. Near-perfect agreement between cross-correlation and waveform optimization methods was observed, while the time-to-upstroke method estimated a significantly larger PWV and was more prone to non-physiological values in a cohort of 21 healthy individuals aged 48 ± 18 years. We then analysed our cohort PWV using an ensemble approach given the current lack of methodological consensus. This analysis identified two consistent findings. First, internal carotids measure significantly higher PWV than basilar vascular networks (3.64 ± 1.47 versus 2.53 ± 1.39 m s-1). Second, in our cohort, intracranial PWV was age-independent. We hypothesize that age independence is a healthy physiological trait to minimize microvascular strain, protecting the integrity of the peripheral bed throughout ageing and cardiac pulsatile deformation. The cause for apparent age independence remains unknown. We also identified that previous work on intracranial PWV is likely biased towards the extracranial vasculature, which may explain the study differences in PWV magnitude and the age-dependent nature.
