In vivo MRI-based 3D Mechanical Stress-Strain Profiles of Carotid Plaques with Juxtaluminal Plaque Haemorrhage: An Exploratory Study for the Mechanism of Subsequent Cerebrovascular Events

Objectives: Atherosclerotic plaque features, such as fibrous cap erosion, ulceration and rupture and presence of haemorrhage in carotid plaque are two important characteristics associated with subsequent cerebrovascular events and juxtaluminal haemorrhage/thrombus (JLH/T) indicates these two high-risk characteristics. This study aims to investigate the association between JLH/T and subsequent events in patients suffering from transient ischaemic attack (TIA). Three-dimensional mechanical analysis was employed to represent the critical mechanical stress (P-CStress) and stretch (P-CStretch) within the plaque. Methods: Fifty TIA patients with mild-to-moderate carotid stenosis (30-69%) underwent high-resolution magnetic resonance imaging (MRI) within 72 h of the acute event and eight were excluded from the analysis due to various reasons. A total of 21 patients were found to have JLH/T in the carotid plaque and 21 did not (N-JLH/T). During a 2-year follow-up period, 11 (52.4%) patients in the JLH/T group experienced recurrent events and none in the N-JLH/T group. Three-dimensional plaque structure was reconstructed based on the in vivo MRI for the mechanical analysis. Results: P-CStress of both groups was comparable (N-JLH/T: 174.45 +/- 63.96 kPa vs. JLH/T: 212.60 +/- 89.54 kPa; p = 0.120), but P-CStretch of JLH/T was significantly bigger than that of N-JLH/T (N-JLH/T: 1.21 +/- 0.08 vs. JLH/T: 2.10 +/- 0.53; p < 0.0001). Moreover, there were much bigger variations in stress and stretch of the JLH/T group during one cardiac cycle than in those of N-JLH/T group.