Magnetic resonance detected carotid plaque hemorrhage is associated with inflammatory features in symptomatic carotid plaques.

Background: Both magnetic resonance detected carotid plaque hemorrhage (MRI PH(+)) and features of inflammation are associated with increased risk of cerebrovascular events in patients with carotid stenosis. To further assess the potential of MRI PH as a biomarker for complicated carotid plaque, its relationship with inflammation needs to be assessed. In this study we assess whether MRI PH(+) carotid plaques are associated with inflammatory infiltration.

Methods: Thirty-five consecutive patients with symptomatic, high-grade carotid stenosis scheduled for carotid endarterectomy had preoperative MRI. The carotid plaques removed at operation were assessed for inflammatory features and compared with MRI findings.

Results: Twenty-one (60%) carotid arteries were MRI PH(+) and 14 (40%) were MRI PH(-). The MRI PH(+) plaques were associated with histologic evidence of plaque hemorrhage, high lipid proportion, and low fibrous content. They also had higher levels of macrophage and lymphoid cells compared with MRI PH(-) plaques (P < 0.05, by χ² test) and were more likely to be AHA VI (P < 0.005, χ² test). MRI PH(+) plaques were also more likely to be graded as unstable based on morphology and cellular composition.

Conclusions: These findings demonstrate an association between MRI PH and signs of active plaque disease. The relationship between inflammatory activity and plaque instability may thus explain the increased risk associated with MRI PH(+) plaques and increased risk of symptoms.