What question did this study set out to answer?

This study aims to compare two methods, real-time phase-contrast MRI and neurovascular ultrasound, for measuring cerebrovascular reserve capacity in healthy individuals.

February 26, 2026Open Access

Real-time phase-contrast MRI can be used to quantify cerebrovascular reserve capacity – a comparative study to neurovascular ultrasound in healthy subjects

Puntos clave

This study aims to compare two methods, real-time phase-contrast MRI and neurovascular ultrasound, for measuring cerebrovascular reserve capacity in healthy individuals.
Investigated 25 healthy subjects without large artery atherosclerosis
Measured cerebrovascular reserve capacity using both neurovascular ultrasound and real-time phase-contrast MRI during a standardized hyperventilation-apnea test
Performed statistical analysis using paired t-test and Pearson correlation at α=0.05
Real-time phase-contrast MRI showed a greater decrease in peak-systolic velocity during hyperventilation than neurovascular ultrasound (34% MCA vs 22% MCA)
Changes in peak-systolic velocity during apnea were similar between both techniques with a mean difference of less than 10%
Quantitative blood flow velocities were lower for RT-PC MRI than for nvUS due to partial volume effects and lower temporal resolution

Resumen

Cerebrovascular reserve capacity (CVRC) is reduced in patients with advanced large artery atherosclerosis (LAA) and represents a risk factor for ischemic stroke. Aim of this study was to compare CVRC testing derived by neurovascular ultrasound (nvUS) and real-time phase-contrast MRI (RT-PC MRI). In this study 25 subjects (age 33±13 years) without any LAA were first investigated with nvUS followed by RT-PC MRI performing a standardized hyperventilation-apnea-test. CVRC was determined in the medial (MCA) and posterior cerebral artery (PCA) using transtemporal nvUS and RT-PC MRI at 25 fps temporal resolution, 0.8×0.8 mm 2 in plane resolution and a slice thickness of 6 mm during free breathing. For statistical analysis a paired t -test and a pearson correlation were used at α=0.05. Overall, peak-systolic velocities (PSV) and end-diastolic velocities (EDV) showed lower values for the RT-PC MRI as compared to nvUS. The PSV-decrease during hyperventilation relative to baseline was higher in RT-PC MRI measurements (22% (MCA) and 26% (PCA) for nvUS vs. 34% (MCA) and 39% (PCA) for RT-PC MRI, p<0.001), while the relative PSV-increase from hyperventilation to apnea was comparable between both modalities with a mean difference of <10% (62% (MCA) and 78% (PCA) for nvUS vs. 70% (MCA) and 84% (PCA) for RT-PC MRI, p=0.171 for MCA and p=0.324 for PCA). Both nvUS and RT-PC MRI based CVRC measurements showed reliable de- and increases in PSV during the standardized breathing protocol. RT-PC MRI represents a promising technique to determine CVRC in various intracranial vessels. • Real-time phase-contrast MRI (RT-PC MRI) can be used to examine cerebrovascular-reserve-capacity (CVRC) during a standardized breathing protocol in various intracranial arteries. • Compared to neurovascular ultrasound (nvUS) relative decrease of peak-systolic velocity (PSV) during hyperventilation was higher for RT-PC MRI derived measurements. • Relative increase of PSV during apnea was comparable between RT-PC MRI and nvUS with a mean difference of <10%. • Dynamic changes of intracranial blood flow are well detectable using RT-PC MRI. • Quantitative blood flow velocities derived by RT-PC MRI are lower compared to nvUS derived blood flow velocities because of partial volume effects and a lower temporal resolution of RT-PC MRI.

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