Background and Purpose: To prospectively evaluate differences in carotid plaque characteristics in symptomatic and asymptomatic patients using high-resolution MRI.
Methods: 20 symptomatic and 20 asymptomatic patients, with at least 50% carotid stenosis as determined by Doppler ultrasound, underwent pre-operative in vivo multi-spectral MRI of the carotid arteries. Studies were analysed both qualitatively and quantitatively in a randomised manner by two experienced readers in consensus, blinded to clinical status, and plaques were classified according to the modified American Heart Association (AHA) criteria.
Results: After exclusion of poor quality images, a total of 109 MRI sections in 18 symptomatic and 19 asymptomatic patients were available for analysis. There were no significant differences in mean luminal stenosis severity (72.9 % vs 67.6 %, p = 0.09) and plaque burden (median plaque areas 50 mm2 vs 50 mm2, p = 0.858) between the symptomatic and asymptomatic groups. However, symptomatic lesions had a higher incidence of ruptured fibrous caps (36.5 % vs 8.7%, p = 0.004), haemorrhage or thrombus (46.5 % vs 14.0 %, p < 0.001), large necrotic lipid cores (63.8 % vs 28.0 %, p = 0.002) and complicated Type VI AHA lesions (61.5% vs 28.1%, p=0.001) compared to asymptomatic lesions. The MRI findings of plaque haemorrhage or thrombus had an odds ratio of 5.25 (95 % CI: 2.08 – 13.24) while thin or ruptured fibrous cap (as opposed to a thick fibrous cap) had an odds ratio of 7.94 (95 % CI: 2.93 – 21.51) for prediction of symptomatic clinical status.
Conclusions: There are significant differences in plaque characteristics between symptomatic and asymptomatic carotid atheroma and these can be detected in vivo by high-resolution MRI.
- carotid artery disease
- magnetic resonance imaging