BACKGROUND AND PURPOSE:MR imaging–detected carotid plaque hemorrhage is associated with an increased risk of recurrent ischemic cerebrovascular events and could be an indicator of disease progression; however, there are limited data regarding the dynamics of the MR imaging–detected carotid plaque hemorrhage signal. We assessed the temporal change of this signal and its impact on carotid disease progression.
MATERIALS AND METHODS:Thirty-seven symptomatic patients with 54 carotid stenoses of >30% on sonography underwent serial MR imaging during 24 months. A signal-intensity ratio of >1.5 between the carotid plaque and adjacent muscle was defined as plaque hemorrhage, and a change in signal-intensity ratio of >0.31 between time points was considered significant. Sixteen patients underwent ≥2 carotid sonography scans to determine the peak systolic velocities and degree of stenosis with time.
RESULTS:Of the 54 carotids, 28 had the presence of hyperintense signal on an MR imaging sequence (PH+) and 26 had the absence of hyperintense signal on an MR imaging sequence (PH−) at baseline. The signal-intensity ratio was stable in 33/54 carotid plaques, but 39% showed a change. Plaque hemorrhage classification did not change in 87% of carotid plaques, but 4 became PH+, and 3, PH−. As a group, PH+ carotids did not change significantly in signal-intensity ratio (
P = .585), whereas PH− showed an increased signal-intensity ratio at 24.5 months (
P = .02). In PH+ plaques, peak systolic velocities significantly increased by 22 ± 39.8 cm/s from baseline to last follow-up sonography (
Z = 2.427,
P = .013).
CONCLUSIONS:During 2 years, MR imaging–detected carotid plaque hemorrhage status remained stable in most (87%) cases with 4 (7%) incident plaque hemorrhages. PH+ plaques were associated with increased flow velocity during the follow-up period.Currently, the degree of ICA stenosis is the principal criterion on the basis of which the decision for carotid intervention is made. This is based on strong evidence from randomized controlled trials that carotid endarterectomy reduces stroke risk in patients with severe carotid artery stenosis.
1,2 However, those studies also showed that a significant proportion of patients with symptomatic carotid disease will not have a recurrence. Subsequently, much research is focused on the identification of high-risk subgroups,
3 especially for those with moderate or asymptomatic carotid stenosis.Plaque hemorrhage (PH) is implicated in carotid plaque vulnerability
4 and is detectable by MR imaging.
5,6 A recent longitudinal follow-up study and meta-analysis
7 demonstrated that MR imaging–detected plaque hemorrhage (MR imaging-PH) strongly predicts recurrent ischemic events. The MR imaging-PH signal seems to be stable for 12 months,
8 but stability of MR imaging-PH features beyond 12 months remains unclear. Knowledge of longer term stability of MR imaging-PH would be helpful if it is to be used to assist decision-making in interventions and to determine the need for follow-up imaging.Plaque volume progression on sonography recently has been shown to predict cerebrovascular events
9; however, this measure was not used in the current study. Carotid stenosis progression has been suggested to be a better predictor of subsequent TIA/stroke than a single measurement.
10 Although general carotid sonography surveillance may not be cost-effective,
11 this situation may well be different for a subgroup of patients with a higher risk for stenosis progression. It is conceivable that MR imaging-PH is also an indicator of disease progression
12 and, therefore, may be useful in this regard.The aim of this study was to determine MR imaging signal changes in the carotid artery plaque during 2 years and whether the presence of MR imaging-PH at baseline is associated with stenosis progression.
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