Carotid artery wall thickness and leukoaraiosis: preliminary results using multidetector row CT angiography

Greater burden of white matter lesions and silent infarcts ipsilateral to carotid stenosis

OBJECTIVES

Carotid stenosis may cause silent cerebrovascular disease (CVD) through atheroembolism and hypoperfusion. If so, revascularization may slow progression of silent CVD. We aimed to compare the presence and severity of silent CVD to the degree of carotid bifurcation stenosis by cerebral hemisphere.

MATERIALS AND METHODS

Patients age ≥40 years with carotid stenosis >50% by carotid ultrasound who underwent MRI brain from 2011-2015 at Mayo Clinic were included. Severity of carotid stenosis was classified by carotid duplex ultrasound as 50-69% (moderate), 70-99% (severe), or occluded. White matter lesion (WML) volume was quantified using an automated deep-learning algorithm applied to axial T2 FLAIR images. Differences in WML volume and prevalent silent infarcts were compared across hemispheres and severity of carotid stenosis.

RESULTS

Of the 183 patients, mean age was 71±10 years, and 39.3% were female. Moderate stenosis was present in 35.5%, severe stenosis in 46.5% and occlusion in 18.0%. Patients with carotid stenosis had greater WML volume ipsilateral to the side of carotid stenosis than the contralateral side (mean difference, 0.42±0.21cc, p=0.046). Higher degrees of stenosis were associated with greater hemispheric difference in WML volume (moderate vs. severe; 0.16±0.27cc vs 0.74±0.31cc, p=0.009). Prevalence of silent infarct was 23.5% and was greater on the side of carotid stenosis than the contralateral side (hemispheric difference 8.8%±3.2%, p=0.006). Higher degrees of stenosis were associated with higher burden of silent infarcts (moderate vs severe, 10.8% vs 31.8%; p=0.002).

CONCLUSIONS

WML and silent infarcts were greater on the side of severe carotid stenosis.

White-matter hyperintensities in patients with carotid artery stenosis: An exploratory connectometry study

BACKGROUND

White-matter lesions (WMLs) are frequently found in magnetic resonance imaging (MRi), and the WML load tends to be higher in patients affected by cervical internal carotid artery (cICA) stenosis.

PURPOSE

This study aimed to investigate whether and how WMLs influence cerebral networking in patients with asymptomatic cICA stenosis eligible for carotid endarterectomy (CEA) by exploiting the connectometry technique.

METHODS

The study was designed as a cross-sectional exploratory investigation, and 28 patients with cICA stenosis eligible for CEA were enrolled. All patients received an MRI scan, including a T1-weighted, a FLAIR and a diffusion-weighted (DW) sequence. The T1 and FLAIR sequences were analysed for quantification of WML burden (WMLB) and total number of WMLs (TNWMLs). The DW data were reconstructed in the MNI space using q-space diffeomorphic reconstruction, and were grouped to create a connectometry database. The connectometry analysis evaluated the influence of both the WMLB and TNWMLs to local connectivity in a multiple regression model that included age, WMLB and TNWMLs, adopting three different T-score thresholds (1, 2 and 3). A p-value corrected for false discovery rate of <0.05 was adopted as a threshold to identify statistically significant results.

RESULTS

The connectometry analysis identified several white-matter bundles negatively correlated with WMLB; no statistically significant correlation was found for TNWMLs.

CONCLUSION

Results of our study suggest that WMLs influence brain connectivity measured by the connectometry technique in patients with cICA stenosis eligible for CEA. Further studies are warranted to understand the role of WMLs better as a marker of disease in patients with cICA stenosis.

Volumetric Distribution of the White Matter Hyper-Intensities in Subject with Mild to Severe Carotid Artery Stenosis: Does the Side Play a Role?

PURPOSE

The purpose of this paper was to assess the difference in the distribution of white matter hyperintensities (WMHs) on left and right sides of the brain hemispheres of subjects with mild to severe carotid artery stenosis.

MATERIAL AND METHODS

Eighty consecutive patients (mean age 71 ± 6 years, males 66) with carotid artery stenosis were prospectively recruited. FLAIR-WMH lesion volume was performed using a semiautomated segmentation technique (Jim, Xinapse System, Leicester, UK). The Wilcoxon test was applied to verify the differences in the volume of WMHs between the right and left hemispheres.

RESULTS

A statistically significant difference was found in the middle cerebral artery (MCA) territory for the volume of the lesions (median volume of WMHs of the left side = 889.5 mm³; median volume of WMHs on the right side = 580.5 mm³; P = .0416); no statistically significant difference was found on the other territories by taking into considerations the lesions. By analyzing the degree of stenosis, we found a higher degree of stenosis of the left side (67.9%; 95% confidence interval [CI], 64.8%-70.9%) compared with the right side (65.7%; 95% CI, 62.4%-68.9%), but the Mann-Whitney test did not show a statistically significant difference (P = .3235).

CONCLUSIONS

Results of our study suggest that there is a difference in the distribution of WMHs in the brain hemispheres according to the left/right side on the MCA territories and for the periventricular white matter in subjects with mild to severe carotid artery stenosis.

Correlation of retinopathy with leukoaraiosis in patients with anterior circulation infarcts

Although retinal and cerebral microvessels share similar embryological, anatomical and physiological characteristics, the correlation between retinopathy and leukoaraiosis (LA), a type of brain microvascular disease, is unclear. In the present study, the sample included 213 patients admitted to the department of neurology from January 2012 through October 2012. MRI and retinal photography were performed within 48hours of hospitalization, and patient demographics, comorbidities, preadmission medications and laboratory data were collected. MRI images were used to divide the patients into LA and non-LA groups. Using multivariate binary logistic regression, the effects of retinopathy on LA were investigated. Of the 213 patients enrolled, 168 were included in this study (LA, n=108; non-LA, n=60). Hypertension, coronary heart disease and carotid artery plaque were more common in the LA group, and these patients showed higher blood levels of C-reactive protein, homocysteine and triglycerides. The incidence of retinopathy was significantly increased in the LA group compared with the non-LA group, and there was a significant correlation between the severity of LA and incidence of retinopathy. Retinopathy is an independent risk factor for LA and can significantly increase the risk of LA when combined with age, coronary heart disease, C-reactive protein, carotid artery plaque or systolic pressure. Taken together, retinopathy is associated with LA in patients with anterior circulation infarcts. Retinopathy is an independent risk factor for LA and an increase the risk of LA, and thus facilitating the evaluation of LA.

The association between leukoaraiosis and carotid atherosclerosis: a systematic review and meta-analysis

The association between large-artery atherosclerosis and leukoaraiosis (LA) has been increasingly reported with inconsistent conclusion. This systematic review examines the relationship between LA and carotid atherosclerosis, manifested as atherosclerotic stenosis, plaques and increased intima-media thickness (IMT). PubMed, Embase, and Web of Science were searched for articles published up to February 2014. Thirty-two studies that examined the relationship between LA and carotid atherosclerosis were included. All statistical analysis was conducted with Review Manager 5.2.4. Finally, 32 studies including 17,721 patients were identified. There were 7 (30%) out of 23 studies reporting significant association between LA and carotid stenosis; 11 (79%) out of 14 studies reporting significant association between LA and carotid plaque; all 9 studies reporting significant association between LA and carotid IMT; one study showing an association between LA and CAWT (similar to the role of the IMT). The quantitative meta-analysis of 10 studies showed that carotid atherosclerosis was not associated with LA (OR: 1.10; 95% CI: 0.61-1.98). A significant association was found between LA and carotid plaque (OR = 3.53; 95% CI = 1.83-6.79), and the result of IMT group showed that IMT increased risk of LA (MD = 0.11; 95% CI = 0.01-0.22). This systematic review suggested that LA has a tendency of association with carotid plaques but no association with simple carotid stenosis.

Is there an association between asymmetry of carotid artery wall thickness (ACAWT) and cerebrovascular symptoms?

PURPOSE

Previous publications demonstrated that multi-detector-row computed tomography Angiography (MDCTA) can evaluate the carotid artery wall thickness (CAWT). The purpose of this work was to compare the asymmetry of CAWT between carotids in symptomatic and asymptomatic patients.

MATERIAL AND METHODS

Sixty consecutive symptomatic (males 44; median age 64) and 60 asymptomatic sex- and age-matched patients were analysed by using a 40-detector-row CT system. CAWT was calculated for both carotids in each patient and the ratio between the thicker CAWT and the contra-lateral was calculated to obtain the ACAWT index. Bland-Altman, logistic regression and receiver operating characteristic (ROC) curve analysis were calculated.

RESULTS

The Bland-Altman plot demonstrates a very good agreement between measurements with a mean difference value of 3.4% and 95% CI from -8% to 14.8%. The ACAWT was significantly different between symptomatic and asymptomatic patients (with a p value of 0.0001). The ROC area under the curve was 0.742 (p = 0.001). Logistic regression model indicated that ACAWT, CAWT, stenosis degree, and fatty plaques were independent variables associated with cerebrovascular symptoms (p value, respectively, 0.0108, 0.0231, 0.0002, and 0.013).

CONCLUSION

Results of our study indicated that the index of asymmetry in the CAWT might be used as a further parameter to stratify the risk of symptoms related to carotid artery.

Imaging of the carotid artery vulnerable plaque

Atherosclerosis involving the carotid arteries has a high prevalence in the population worldwide. This condition is significant because accidents of the carotid artery plaque are associated with the development of cerebrovascular events. For this reason, carotid atherosclerotic disease needs to be diagnosed and those determinants that are associated to an increased risk of stroke need to be identified. The degree of stenosis typically has been considered the parameter of choice to determine the therapeutical approach, but several recently published investigations have demonstrated that the degree of luminal stenosis is only an indirect indicator of the atherosclerotic process and that direct assessment of the plaque structure and composition may be key to predict the development of future cerebrovascular ischemic events. The concept of "vulnerable plaque" was born, referring to those plaque's parameters that concur to the instability of the plaque making it more prone to the rupture and distal embolization. The purpose of this review is to describe the imaging characteristics of "vulnerable carotid plaques."

Association between carotid artery plaque type and cerebral microbleeds

BACKGROUND AND PURPOSE

CMBs have become increasingly recognized with the widespread use of MR imaging techniques that are sensitive to iron deposits. The purpose of this study was to correlate the presence of CMBs and carotid plaque characteristics.

MATERIAL AND METHODS

Seventy consecutive patients (47 men; 23 women; mean age, 65 years) were prospectively analyzed. Carotid arteries were studied using a 16-detector row CT scanner, whereas the brain was explored with an MR imaging 1.5T system. CMBs were studied using a T2*-weighted GRE sequence. CMBs were classified by an ordinal scale and carotid plaques were characterized based on their composition as fatty, mixed, or calcified. Patients were classified as symptomatic and asymptomatic. Chi-square and multiple logistic regression analyses, as well as ROCs, were calculated.

RESULTS

The prevalence of CMBs was 30%. A statistically significant difference in CMB prevalence was observed between symptomatic (46%) and asymptomatic (19%) patients (P value = .0021; OR = 3.7). Correlation analysis demonstrated an association between the number of CMBs and the symptoms (P = .0001). A statistically significant association was observed between the presence of fatty plaque and CMBs (P = .0019).

CONCLUSIONS

The results of this study suggest an association between the presence of carotid artery fatty plaque, symptoms, and CMBs. Moreover, we found that the presence (and entity) of CMBs may represent an indicator of cerebrovascular symptom severity.