Abstract
PurposeThe aim of this study was to investigate prospectively whether MRI plaque imaging can identify patients with asymptomatic carotid artery stenosis who have an increased risk for future cerebral events. MRI plaque imaging allows categorization of carotid stenosis into different lesion types (I–VIII). Within these lesion types, lesion types IV–V and VI are regarded as rupture-prone plaques, whereas the other lesion types represent stable ones.MethodsEighty-three consecutive patients (45 male (54.2%); age 54–88 years (mean 73.2 years)) presenting with an asymptomatic carotid stenosis of 50–99% according to ECST-criteria were recruited. Patients were imaged with a 1.5-T scanner. T1-, T2-, time-of-flight-, and proton-density weighted studies were performed. The carotid plaques were classified as lesion type I–VIII. Clinical endpoints were ischemic stroke, TIA or amaurosis fugax. Survival analysis and log rank test were used to ascertain statistical significance.ResultsSix out of 83 patients (7.2%) were excluded: 4 patients had insufficient MR image quality; 1 patient was lost-to-follow-up; 1 patient died shortly after the baseline MRI plaque imaging. The following results were obtained by analyzing the remaining 77 patients. The mean time of follow-up was 41.1 months.During follow-up, n = 9 (11.7%) ipsilateral ischemic cerebrovascular events occurred. Only patients presenting with the high-risk lesion types IV–V and VI developed an ipsilateral cerebrovascular event versus none of the patients presenting with the stable lesion types III, VII, and VIII (n = 9 (11.7%) vs. n = 0 (0%) during follow-up). Event-free survival was higher among patients with the MRI-defined stable lesion types (III, VII, and VIII) than in patients with the high-risk lesion types (IV–V and VI) (log rank test P<0.0001).ConclusionsMRI plaque imaging has the potential to identify patients with asymptomatic carotid stenosis who are particularly at risk of developing future cerebral ischemia. MRI could improve selection criteria for invasive therapy in the future.
Highlights
Carotid artery stenosis (CS) represents a risk factor for cerebral infarction
Among the 83 patients (45 male (54.2%); age 54–88 years) available, 4 were excluded because of insufficient MR image quality; 1 patient was lost-to-follow-up; 1 patient died shortly after the baseline magnetic resonance imaging (MRI) plaque imaging because of renal failure
Patients presenting with the high-risk lesion types IV–V and VI developed an ipsilateral cerebrovascular event versus none of the patients presenting with the stable lesion types III, VII, and VIII (n = 9 (11.7%) vs. n = 0 (0%) during follow-up)
Summary
Pooled data from the Asymptomatic Carotid Atherosclerosis Study (ACAS) [1] and the Asymptomatic Carotid Surgery trial (ACST) [2] revealed that around 89% of the patients did not have a cerebrovascular event for 5 years when treated medically These data highlight the importance of other criteria than the degree of stenosis, which still represents the main parameter for risk estimation in CS. Cai and colleagues modified this histological classification for multicontrast MRI application [20] Using this modified classification, plaques containing a thinned fibrous cap with a lipid-rich necrotic core[21] can be categorized as lesion type IV–V and plaque features such as intraplaque hemorrhage belong to lesion type VI [9,21]
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