Combined imaging, computational and histological analysis of a ruptured carotid plaque: A patient-specific analysis

Abstract 

Background

Rupture of carotid plaques is an important cause of cerebrovascular events. Several factors, including wall shear stress (WSS), plaque morphology and peak cap stress, have been associated with plaque vulnerability. The aim of this study was to investigate the relationship between these factors in an in vivo human ruptured carotid plaque.

Methods

A 74-year-old male presenting with a transient ischemic attack underwent carotid magnetic resonance imaging (MRI), which indicated a ruptured plaque, followed by carotid endarterectomy, from which plaque histology was assessed. The carotid bifurcation was reconstructed from the MRI data, and three-dimensional flow simulations were performed using computational fluid dynamics to determine WSS and related parameters. Plaque vulnerability was assessed using a biomechanical method based on modified Glagov criteria.

Results

The plaque rupture was just distal to the site of maximum stenosis in a region of low WSS, where MRI and histology both demonstrated fibrous cap thinning, a large lipid pool and calcification in the shoulder region. Plaque vulnerability analysis indicated critically vulnerable plaque at the rupture site by a wide margin.

Conclusions

Both low and high WSS have been associated with plaque vulnerability, and high mechanical stress in the cap has been linked to plaque rupture, but these parameters are not routinely assessed clinically. This study demonstrates a complete analysis by combining imaging, histology and bio-fluid and biomechanical modelling.

Keywords: Carotid stenosis, MRI, Computational biomechanics, Computational haemodynamics, Plaque rupture