A Magnetic Resonance Imaging-based Computational Protocol for Analysis of Plaque Morphology and Hemodynamics in Patients with Carotid Artery Stenosis.

Current assessment and management of internal carotid artery (ICA) stenosis is based on the estimation of percentage stenosis via duplex ultrasound (DUS) or computed tomography angiography (CTA), which does not account for physiologically relevant risk factors for stroke, such as plaque vulnerability and hemodynamics. Knowledge of the composition of the carotid plaque and hemodynamic loads on the plaque can be used to provide a much more complete assessment of the embolic potential of the plaque rather than using percentage stenosis alone. Through pairing magnetic resonance imaging (MRI) and patient-specific computational fluid dynamics (CFD), differences in both hemodynamics across an ICA stenosis and plaque composition can be identified. Quantitative multi-contrast atherosclerosis characterization (qMatch) MRI allows for detailed analysis of plaque composition. CFD models can be created using phase contrast (PC) MRI, which can be used to obtain flow waveforms and CTA and/or time-of-flight (TOF)-MRI anatomy. After creating a 3D geometric model of the carotid bifurcation, PC-MRI derived waveforms are prescribed to the common carotid artery inflow and external carotid artery outflow. A three-element Windkessel model, which is iteratively tuned to match the patient's blood pressure, is then prescribed to the ICA. Finally, solutions to the incompressible Navier-Stokes equations are obtained to provide high-resolution velocity and pressure and thus capture hemodynamics across the carotid bifurcation and ICA stenosis. This article provides a detailed protocol that allows for non-invasive and patient-specific characterization of plaque composition and hemodynamic loads of patients with ICA stenosis.