Real-time phase-contrast (RT-PC) flow MRI adds to clinical diagnostics in patients with carotid stenosis, according to a study published in the European Journal of Radiology.

The assessment of carotid artery flow by neurovascular ultrasound (nvUS) can be complemented by real-time phase-contrast (RT-PC) flow MRI which apart from quantitative flow parameters offers velocity distributions across the entire vessel lumen.

Researchers from Germany performed a small study with 20 healthy subjects to examine the utility and accuracy of assessing carotid artery flow by neurovascular ultrasound (nvUS), complemented by real-time phase-contrast (RT-PC) flow MRI.

The feasibility and diagnostic potential of RT-PC flow MRI were in comparison to conventional nvUS. RT-PC flow MRI at 40 ms temporal resolution and 0.8 mm in-plane resolution resulted in velocity maps with low phase noise and high spatiotemporal accuracy by exploiting respective advances of a recent nonlinear inverse model-based reconstruction.

Peak-systolic velocities

Peak-systolic velocities (PSV), end-diastolic velocities (EDV), flow volumes and absolute velocity profiles were determined in the joint, internal and external carotid artery on both sides.

The results showed flow characteristics such as pulsatility and individual abnormalities shown on nvUS could be reproduced and visualized in detail by RT-PC flow MRI.

PSV to EDV differences revealed a good agreement between both techniques, mean PSV and EDV were significantly lower and flow volumes were higher for MRI.

The researchers concluded that their findings suggested RT-PC flow MRI adds to clinical diagnostics, alterations of dynamic velocity distributions in patients with carotid stenosis, and other means.

Lower PSV and EDV values than for nvUS mainly reflect the longer MRI acquisition time which attenuates short peak velocities, while higher flow volumes benefit from a proper assessment of the true vessel lumen.

RT-PC flow MRI of the carotid arteries is feasible and likely to provide additional diagnostic information for the assessment of brain-supplying arteries. These include detailed qualitative blood flow characteristics in the carotid arteries such as two-dimensional velocity profiles.

Moreover, the method allows for flow measurements in patients with severe plaques and elongations of the carotid arteries. Both aspects represent distinct advantages compared to nvUS.

Future studies should use RT-PC flow MRI to investigate spatial velocity patterns in different pathologies of cerebral vessels, e.g., due to vasculitic or arteriosclerotic changes including asymptomatic and low-grade carotid stenosis.

Other possible applications refer to clinical conditions such as severe kinking/coiling of the carotid arteries and vulnerable plaques to assess altered blood flow and associated thromboembolic risk.