MRI of carotid atherosclerosis to identify TIA and stroke patients who are at risk of a recurrence.

PURPOSE: To evaluate the potential of carotid plaque MRI to predict transient ischemic attack (TIA) and stroke recurrence in previously symptomatic patients. MATERIALS AND METHODS: One hundred twenty-six TIA/stroke patients with ipsilateral 30-69% carotid stenosis underwent multisequence carotid plaque MRI. The presence of a lipid-rich necrotic core (LRNC), fibrous cap (FC) status, and intraplaque hemorrhage (IPH) were assessed. Patients were followed to determine the recurrence of ipsilateral TIA and/or stroke within 1 year after inclusion. RESULTS: Thirteen patients suffered from recurrent ipsilateral clinical ischemic events (10 TIAs and 3 strokes). Carotid stenosis grade was not associated with recurrent events (hazard ratio [HR] for 50-69% versus 30-49% stenosis = 1.198; 95% confidence interval [CI], 0.383 to 3.749; P = 0.756). The presence of an LRNC (HR = 3.2001; 95% CI, 1.078 to 9.504; P = 0.036), a thin and/or ruptured FC (HR = 5.756; 95% CI, 1.913 to 17.324; P = 0.002), and IPH (HR = 3.542; 95% CI, 1.058 to 11.856; P = 0.040) were associated with recurrence. CONCLUSION: The presence of MRI-depicted LRNC, a thin and/or ruptured FC, and IPH are associated with the recurrence of clinical cerebrovascular ischemic events in TIA and stroke patients with carotid atherosclerosis.

Association between carotid plaque characteristics and cerebral white matter lesions: one-year follow-up study by MRI.

OBJECTIVE: To prospectively assess the relation between carotid plaque characteristics and the development of new cerebral white matter lesions (WMLs) at MRI. METHODS: Fifty TIA/stroke patients with ipsilateral 30-69% carotid stenosis underwent MRI of the plaque at baseline. Total plaque volume and markers of vulnerability to thromboembolism (lipid-rich necrotic core [LRNC] volume, fibrous cap [FC] status, and presence of intraplaque hemorrhage [IPH]) were assessed. All patients also underwent brain MRI at baseline and after one year. Ipsilateral cerebral WMLs were quantified with a semiautomatic method. RESULTS: Mean WML volume significantly increased over a one-year period (6.52 vs. 6.97 mm(3), P = 0.005). WML volume at baseline and WML progression did not significantly differ (P>0.05) between patients with 30-49% and patients with 50-69% stenosis. There was a significant correlation between total plaque volume and baseline ipsilateral WML volume (Spearman ρ = 0.393, P = 0.005). There was no significant correlation between total plaque volume and ipsilateral WML progression. There were no significant associations between LRNC volume and WML volume at baseline and WML progression. WML volume at baseline and WML progression did not significantly differ between patients with a thick and intact FC and patients with a thin and/or ruptured FC. WML volume at baseline and WML progression also did not significantly differ between patients with and without IPH. CONCLUSION: The results of this study indicate that carotid plaque burden is significantly associated with WML severity, but that there is no causal relationship between carotid plaque vulnerability and the occurrence of WMLs.

Carotid plaques in transient ischemic attack and stroke patients: one-year follow-up study by magnetic resonance imaging.

OBJECTIVE: To investigate the natural course of carotid plaque progression in transient ischemic attack/stroke patients by using serial multisequence magnetic resonance imaging (MRI). MATERIALS AND METHODS: Forty transient ischemic attack/stroke patients with ipsilateral <70% carotid stenosis underwent MRI of the plaque ipsilateral to the symptomatic side at baseline and after 1 year. The MRI protocol consisted of T1-weighted turbo field-echo, time-of-flight, T2-weighted turbo spin-echo (TSE), and pre- and postgadopentetate dimeglumine-enhanced T1-weighted TSE images. For each plaque, carotid lumen volume, wall volume, total vessel volume (=carotid lumen volume + wall volume), the presence of a lipid-rich necrotic core (LRNC), fibrous cap (FC) status, and the presence of intraplaque hemorrhage (IPH) were assessed at both time points. RESULTS: Over a 1-year period, mean carotid lumen volume decreased with 4.8% ± 2.0% (±standard error) (P = 0.013). Mean wall volume increased with 11.2% ± 2.2% (P < 0.001). Total vessel volume did not significantly change (P = 0.147). At baseline, there were 18 plaques with a LRNC, which also had a LRNC at 1-year follow-up. No plaque without a LRNC at baseline developed a LRNC during the follow-up period. All plaques with a LRNC had a thin and/or ruptured FC at both time points. Twelve patients had IPH both at baseline and at follow-up. In one patient, IPH disappeared, whereas in another patient, new IPH appeared at follow-up. The presence of IPH and a LRNC with a thin and/or ruptured FC were not significantly associated with plaque progression (P > 0.05). CONCLUSIONS: In symptomatic patients with an ipsilateral carotid plaque causing <70% stenosis, we found evidence for inward plaque remodeling over a 1-year period. Overall, the presence/absence of IPH, a LRNC, and FC status did not change over 1 year.

Symptomatic patients with mild and moderate carotid stenosis: plaque features at MRI and association with cardiovascular risk factors and statin use.

BACKGROUND AND PURPOSE: The objectives of this study were to assess plaque characteristics in symptomatic patients with mild and moderate carotid stenosis and to explore associations with cardiovascular risk factors and statin use. METHODS: One hundred patients with transient ischemic attack or stroke with ipsilateral mild and moderate carotid stenosis underwent MR plaque imaging. RESULTS: Patients with moderate stenosis had plaques with a higher prevalence of intraplaque hemorrhage (48.7% versus 19.7%, P=0.002) and a thin and/or ruptured fibrous cap (61.5% versus 36.1%, P=0.013), and larger lipid-rich necrotic core percentage (12.3% versus 6.8%, P=0.042) and smaller fibrous tissue percentage (82.7% versus 88.4%, P=0.024). Increasing age was positively associated with intraplaque hemorrhage (OR [per year]=1.08; 95% CI, 1.02 to 1.14; P=0.011). Statin use was negatively associated with intraplaque hemorrhage (OR=0.30; 95% CI, 0.10 to 0.93; P=0.038), a thin and/or ruptured fibrous cap (OR=0.34; 95% CI, 0.13 to 0.89; P=0.028), and with lipid-rich necrotic core percentage (B=-7.91; 95% CI, -13.60 to -2.22; P=0.007). Statin use was positively associated with fibrous tissue percentage (B=7.77; 95% CI, 2.40 to 13.14; P=0.005). CONCLUSIONS: We found that symptomatic patients with moderate stenosis have a higher prevalence of complicated plaques than patients with mild stenosis. Exploratory analysis showed that increasing age was positively associated with intraplaque hemorrhage, whereas statin use was negatively associated with complicated plaque features.

Multimodality imaging of carotid artery plaques: 18F-fluoro-2-deoxyglucose positron emission tomography, computed tomography, and magnetic resonance imaging.

BACKGROUND AND PURPOSE: This study's objective was to compare (18)F-fluoro-2-deoxyglucose positron emission tomography ((18)F-FDG PET), CT, and MRI of carotid plaque assessment. MATERIALS AND METHODS: Fifty patients with symptomatic carotid atherosclerosis underwent (18)F-FDG PET/CT and MRI. Correlations and agreement between imaging findings were assessed by Spearman and Pearson rank correlation tests, t tests, and Bland-Altman plots. RESULTS: Spearman rho between plaque (18)F-FDG standard uptake values and CT/MRI findings varied from -0.088 to 0.385. Maximum standard uptake value was significantly larger in plaques with intraplaque hemorrhage (1.56 vs 1.47; P=0.032). Standard uptake values did not significantly differ between plaques with an intact and thick fibrous cap and plaques with a thin or ruptured fibrous cap on MRI. (1.21 vs 1.23; P=0.323; and 1.45 vs 1.54; P=0.727). Pearson rho between CT and MRI measurements varied from 0.554 to 0.794 (P<0.001). For lipid-rich necrotic core volume, the CT-MRI correlation was stronger in mildly (10%) calcified plaques (Pearson rho 0.730 vs 0.475). Mean difference in measurement +/-95% limits of agreement between CT and MRI for minimum lumen area, volumes of vessel wall, lipid-rich necrotic core, calcifications, and fibrous tissue were 0.4+/-18.1 mm(2) (P=0.744), -41.9 +/-761.7 mm(3) (P=0.450), 78.4+/-305.0 mm(3) (P<0.001), 180.5+/-625.7 mm(3) (P=0.001), and -296.0+/-415.8 mm(3) (P<0.001), respectively. CONCLUSIONS: Overall, correlations between (18)F-FDG PET and CT/MRI findings are weak. Correlations between CT and MRI measurements are moderate to strong, but there is considerable variation in absolute differences.

Reproducibility of fibrous cap status assessment of carotid artery plaques by contrast-enhanced MRI.

BACKGROUND AND PURPOSE: Reproducibility in identifying the fibrous cap (FC) of carotid artery plaques by noncontrast-enhanced MRI has been shown to be poor. The objective of this study was to assess the reproducibility of multisequence MRI, including contrast-enhanced images, in assessing FC status. METHODS: Forty-five symptomatic patients with 30% to 69% carotid artery stenosis underwent a multisequence MRI protocol, which included contrast-enhanced images. FC status (ie, discrimination between fibrotic and/or calcified plaques, plaques with a lipid-rich necrotic core and an intact and thick FC, and plaques with a lipid-rich necrotic core and a thin and/or ruptured FC) was independently assessed by 3 observers of which one also scored all images on a different occasion. Linear weighted kappa coefficients (kappa) were calculated as indicators of inter- and intraobserver agreement. RESULTS: On a per-slice basis, interobserver agreement was good (kappa=0.60, 0.64, and 0.71), whereas intraobserver agreement was very good (kappa=0.86). On a per-plaque basis, interobserver agreement was good (kappa=0.64, 0.69, and 0.78), whereas intraobserver agreement was very good (kappa=0.96). CONCLUSIONS: This study found good interobserver and very good intraobserver agreement in assessing FC status of carotid artery plaques. Future studies are warranted to determine the predictive value of FC status assessment by multisequence MRI, including contrast-enhanced images, on the occurrence of (recurrent) cerebral ischemic events.