Assessment of hemodynamic changes near carotid atherosclerotic plaques by using magnetic resonance imaging and computational fluid dynamics

Abstract

Objective To establish a platform by using carotid MRI and computational fluid dynamics (CFD) to assess hemodynamic changes around carotid atherosclerotic plaques.  Methods Thirteen patients with carotid atherosclerosis were recruited in this study. Six volunteers were regarded as normal controls. All the patients and volunteers underwent carotid MRI and contrast-enhanced magnetic resonance angiography (CEMRA). Carotid MRI was used to visualize the plaque structures and components. All plaques were divided into different types according to plaque components. CEMRA images were used to obtain three-dimensional (3D) models of carotid bifurcations, whose boundary conditions were specified using CFD front-end software, and then the mesh file of the 3D models were obtained to import to CFD software to visualize hemodynamic maps, including wall shear stress (WSS), static pressure and blood velocity.  Results Fifteen diseased internal carotid arteries (ICAs) were assessed. According to the MRI appearance of the plaques, the types of these plaques were from Ⅳ-Ⅴ to Ⅷ. All of these were vulnerable plaques which caused irregular stenosis of ICAs. The WSS, static pressure and blood velocity were (79.86 ± 57.83) Pa, (-7586.81 ± 9313.83) Pa, (2.76±1.81) m/s, respectively in the diseased ICAs group and (2.52 ± 0.58) Pa, (-71.65 ± 30.89) Pa, (0.21 ± 0.06) m/s, respectively in the normal control group. In the diseased ICAs group WSS was elevated heterogenously and static pressure was decreased heterogenously near the plaques. The blood velocity near the plaques was increased but still streamlined. Statistical significant differences were shown for WSS, static pressure and blood velocity between 2 groups (P = 0.000, for all).  Conclusions The platform combining MRI and CFD can be used to analyze the plaque structures and fluid dynamic change near the plaques, suggesting hemodynamics plays an important role in the plaque progression and vulnerability.

doi: 10.3969/j.issn.1672-6731.2014.07.011