Hyperglycemia, duration of diabetes, and intracranial atherosclerotic stenosis by magnetic resonance angiography: The ARIC-NCS study

AIMS

The association of hyperglycemia and duration of diabetes with intracranial atherosclerotic stenosis (ICAS) in the general population is not well documented. We examined whether elevated glucose and longer diabetes duration is independently associated with ICAS in a community-based sample.

METHODS

We cross-sectionally analyzed 1644 participants (age 67-90 years) of the Atherosclerosis Risk in Communities Study who underwent cerebrovascular magnetic resonance angiography in 2011-13. We applied multivariable ordinal logistic regression to evaluate the association of ICAS category ("no stenosis", "stenosis <50%", or "stenosis ≥50%") with glucose or diabetes duration (<10, 10 to 20, and ≥20 years). We also obtained the corresponding odds ratios applying inverse-probability weighting to account for potential selection bias due to attrition.

RESULTS

Compared to non-diabetic participants in the lowest glucose quartile, the weighted odds ratios (95% confidence interval) of higher ICAS category were 1.88 (1.18, 3.00) and 2.01 (1.08, 3.72) for non-diabetic and diabetic participants in the corresponding highest glucose quartile, respectively. We observed significant positive trends of ICAS across diabetes duration categories in unweighted, but not in weighted, analyses.

CONCLUSIONS

Hyperglycemia and longer duration of diabetes were independently associated with ICAS, suggesting the importance of maintaining glycemic control to prevent stroke.

Vessel wall MR imaging of intracranial atherosclerosis

Intracranial atherosclerotic disease (ICAD) is one of the most common causes of ischemic stroke worldwide. Along with high recurrent stroke risk from ICAD, its association with cognitive decline and dementia leads to a substantial decrease in quality of life and a high economic burden. Atherosclerotic lesions can range from slight wall thickening with plaques that are angiographically occult to severely stenotic lesions. Recent advances in intracranial high resolution vessel wall MR (VW-MR) imaging have enabled imaging beyond the lumen to characterize the vessel wall and its pathology. This technique has opened new avenues of research for identifying vulnerable plaque in the setting of acute ischemic stroke as well as assessing ICAD burden and its associations with its sequela, such as dementia. We now understand more about the intracranial arterial wall, its ability to remodel with disease and how we can use VW-MR to identify angiographically occult lesions and assess medical treatment responses, for example, to statin therapy. Our growing understanding of ICAD with intracranial VW-MR imaging can profoundly impact diagnosis, therapy, and prognosis for ischemic stroke with the possibility of lesion-based risk models to tailor and personalize treatment. In this review, we discuss the advantages of intracranial VW-MR imaging for ICAD, the potential of bioimaging markers to identify vulnerable intracranial plaque, and future directions of artificial intelligence and its utility for lesion scoring and assessment.

Association between kidney disease measures and intracranial atherosclerosis: The ARIC study

OBJECTIVE

To test the association between reduced kidney function (assessed by estimated glomerular filtration rate [eGFR] and cystatin C [CysC]) and kidney damage (assessed by urinary albumin-to-creatinine ratio [ACR]) and intracranial atherosclerotic disease (ICAD) by high-resolution vessel wall MRI (VWMRI) in the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS).

METHODS

We conducted a cross-sectional analysis of ARIC participants with data on kidney measures and VWMRI in 2011 to 2013. The main outcomes were presence of intracranial plaques and luminal stenosis. Multivariable models were adjusted for demographics, cardiovascular risk factors, and use of antithrombotic medications.

RESULTS

A total of 1,762 participants (mean ± SD age, 76.3 ± 5.3) were included. eGFR based on CysC (eGFRcysc) <60 mL/min/1.73 m2 (vs ≥60 mL/min/1.73 m2) was associated with plaque presence (adjusted odds ratio [OR] 1.29, 95% confidence interval [CI] 1.04-1.60), any detectable stenosis (adjusted OR 1.31, 95% CI 1.04-1.63), and >70% stenosis or occlusion (adjusted OR 2.15, 95% CI 1.32-3.50). Neither ACR nor CysC showed statistically significant associations with ICAD features in adjusted models. In adjusted multinomial models, participants with eGFRcysc <60 mL/min/1.73 m2 (vs ≥60 mL/min/1.73 m2) had an increased OR of 1.41 (95% CI 1.06-1.87) for having 1 plaque (vs none) but no significant increase for multiple plaques; ACR ≥30 was associated with moderate (50%-70%) stenosis (OR 2.01, 95% CI 1.14-3.55) vs absent or less than 50% stenosis.

CONCLUSION

In community-dwelling older adults, reduced kidney function or elevated kidney damage was associated with ICAD measured by VWMRI. This finding may help to better identify a population at high risk for ICAD.

Racial Differences in Prevalence and Risk for Intracranial Atherosclerosis in a US Community-Based Population

Importance

Intracranial atherosclerotic disease (ICAD) is an important cause of stroke; however, little is known about racial differences in ICAD prevalence and its risk factors.

Objective

To determine racial differences in ICAD prevalence and the risk factors (both midlife and concurrent) associated with its development in a large, US community-based cohort.

Design, Setting, and Participants

Analysis of 1752 black and white participants recruited from the Atherosclerosis Risk in Communities (ARIC) cohort study who underwent 3-dimensional intracranial vessel wall magnetic resonance imaging from October 18, 2011 to December 30, 2013; data analysis was performed from October 18, 2011 to May 13, 2015.

Exposures

Midlife and concurrent cardiovascular risk factors.

Main Outcomes and Measures

Intracranial plaque presence, size (maximum normalized wall index) and number were assessed by vessel wall magnetic resonance imaging. Midlife and concurrent vascular risk factor associations were determined by Poisson regression (plaque presence), negative binominal regression (plaque number), and linear regression (plaque size), and compared between races.

Results

Of the 1752 study participants (mean [SD] age, 77.6 [5.3] years; range, 67-90 years), 1023 (58.4%) were women and 518 (29.6%) were black. Black men had the highest prevalence (50.9% vs 35.9% for black women, 35.5% for white men, and 30.2% for white women; P < .001) and the highest frequency (22.4% vs 12.1% for black women, 10.7% for white men, and 8.7% for white women; P < .01) of multiple plaques. Prevalence increased with age, reaching 50% before ages 68, 84, and 88 years in black men, white men, and white women, respectively (ICAD prevalence remained <50% in black women). Midlife hypertension and hyperlipidemia were associated with 29% (prevalence ratio [PR], 1.29; 95% CI, 1.08-1.55) and 18% (PR, 1.18; 95% CI, 0.98-1.42), respectively, increased ICAD prevalence with no significant differences between races. Midlife hypertension was also associated with larger plaques (1.11 higher mean maximum normalized wall index; 95% CI, 0.21-2.01). Midlife smoking and diabetes were associated with increased risk of ICAD in black individuals (102% [PR, 2.02; 95% CI, 1.12-3.63] and 57% [PR, 1.57; 95% CI, 1.13- 2.19], respectively), but not in white participants (P < .05 interaction by race).

Conclusions and Relevance

The prevalence of ICAD was highest in black men. Midlife smoking and diabetes were strongly associated with late-life ICAD in blacks only, whereas midlife hypertension and hyperlipidemia were associated with late-life ICAD in both races. These associations may help to explain racial differences in US stroke rates and offer insight into preventive risk-factor management strategies.

Carotid artery imaging: The study of intra-plaque vascularization and hemorrhage in the era of the "vulnerable" plaque

Intraplaque hemorrhage (IPH) is one of the main factors involved in atherosclerotic plaque (AP) instability. Its recognition is crucial for the correct staging and management of patients with carotid artery plaques to limit ischemic stroke. Imaging plays a crucial role in identifying IPH, even if the great variability of intraplaque vascularization and the limitations of our current imaging technologies make it difficult. The intent of this review is to give a general overview of the main features of intraplaque vascularization and IPH on Ultrasound (US), Computed Tomography (CT), Magnetic Resonance (MR) and Nuclear Medicine, and a brief description on the future prospectives.

Imaging biomarkers of vulnerable carotid plaques for stroke risk prediction and their potential clinical implications

Stroke represents a massive public health problem. Carotid atherosclerosis plays a fundamental part in the occurence of ischaemic stroke. European and US guidelines for prevention of stroke in patients with carotid plaques are based on quantification of the percentage reduction in luminal diameter due to the atherosclerotic process to select the best therapeutic approach. However, better strategies for prevention of stroke are needed because some subtypes of carotid plaques (eg, vulnerable plaques) can predict the occurrence of stroke independent of the degree of stenosis. Advances in imaging techniques have enabled routine characterisation and detection of the features of carotid plaque vulnerability. Intraplaque haemorrhage is accepted by neurologists and radiologists as one of the features of vulnerable plaques, but other characteristics-eg, plaque volume, neovascularisation, and inflammation-are promising as biomarkers of carotid plaque vulnerability. These biomarkers could change current management strategies based merely on the degree of stenosis.

Temporal course and implications of intracranial atherosclerotic plaque enhancement on high-resolution vessel wall MRI

PURPOSE

Little is known about the natural history of intracranial atherosclerotic plaque enhancement and its clinical implications. Our objective was to investigate the value of follow-up high-resolution contrast-enhanced vessel wall MRI (VWMRI) for classifying culprit plaques in patients with intracranial atherosclerotic disease (ICAD).

METHODS

Fourteen patients with symptomatic ICAD (50% females; median age 48 years) underwent serial 3T VWMRI. Fifty-five plaques were identified and graded based on the likelihood of having caused the ischemic event (non-culprit, indeterminate, culprit) and degree of enhancement (0, 1, 2) at baseline and follow-up (median follow-up, 140 days). For accuracy analysis, plaque enhancement at baseline and stable or increasing plaque enhancement at follow-up was tested to identify a culprit plaque, and areas under the receiver operating characteristic curves (AUCs) were compared.

RESULTS

In 37/55 (67.3%) plaques, enhancement grade remained unchanged. Lack of enhancement was only seen in non-culprit plaques at baseline, and none developed enhancement over time. Enhancement never changed more than one grade. Thirty-seven percent (10/27) of non-culprit plaques that enhanced decreased in enhancement grade at follow-up, but no culprit plaques decreased in enhancement. AUC of baseline and follow-up plaque enhancement combined was significantly larger than AUC of baseline plaque enhancement alone to identify culprit plaques (0.733 vs. 0.567, p = 0.0001).

CONCLUSION

Contrast enhancement of ICAD can persist months after the ischemic event. Lack of enhancement at baseline or a decrease in enhancement at follow-up suggests that the plaque is not culprit. Persistent enhancement from baseline to follow-up improves accuracy in identifying culprit plaques.

Abstract TP157: Ethnic Difference in Stroke Recurrence for Patients With Intracranial Atherosclerotic Stenosis

Background: Intracranial atherosclerotic stenosis (ICAS), one of most common stroke subtypes worldwide, carries high risk of stroke recurrence despite maximal medical treatment. ICAS more commonly affects non-white populations including Asian, African-American and Hispanic individuals. It is plausible that non-white stroke patients with ICAS might also have more active disease, and thus higher risks of stroke recurrence. We aim to compare the rate of stroke recurrence in stroke patients with ICAS in white and non-white population. Method: We retrospectively reviewed a consecutive series of patients with ischemic stroke due to ICAS in major vessels (MCA, ACA, PCA, intracranial segment of ICA and VA, BA) with >50% stenosis identified on MRA or CTA. The clinical characteristics, risk factors and rate of stroke recurrence were compared in white and non-white patients, using Chi-square (for categorical variables) test and t-test (for continuous variables).

Results: A total of 183 patients [66.3% non-white, mean (SD) age, 63 (±14) years] who were hospitalized between January 2005 and December 2010 and satisfied the inclusion criteria were included in the analysis. Compared with white patients, non-white patients had a higher rate of HTN, DM and drug abuse (Table 1), as well a nonsignificantly higher stroke recurrence rate (3 months: OR 1.29, 95% CI 0.59-2.82; long term: OR 1.63, 95% CI 0.84 - 3.18). History of CKD was the only factor associated with 3-month stroke recurrence (OR 3.73, 965 CI 1.13-12.31).

Conclusion: White and non-white ischemic stroke patients with ICAS have distinct risk factor profiles and possibly distinct stroke recurrence rates. Analysis with a larger sample size is ongoing to verify this finding.

Segment-specific associations between local haemodynamic and imaging markers of early atherosclerosis at the carotid artery: an in vivo human study

Low and oscillatory wall shear stress (WSS) has long been hypothesized as a risk factor for atherosclerosis; however, evidence has been inferred primarily from model and post-mortem studies, or clinical studies of patients with already-developed plaques. This study aimed to identify associations between local haemodynamic and imaging markers of early atherosclerosis. Comprehensive magnetic resonance imaging allowed quantification of contrast enhancement (CE) (a marker of endothelial dysfunction) and vessel wall thickness at two distinct segments: the internal carotid artery bulb and the common carotid artery (CCA). Strict criteria were applied to a large dataset to exclude inward remodelling, resulting in 41 cases for which personalized computational fluid dynamic simulations were performed. After controlling for cardiovascular risk factors, bulb wall thickening was found to be weakly, but not significantly, associated with oscillatory WSS. CE at the bulb was significantly associated with low WSS (p < 0.001) and low flow helicity (p < 0.05). No significant associations were found for the CCA segment. Local haemodynamics at the bulb were significantly correlated with blood flow rates and heart rates, but not carotid bifurcation geometry (flare and curvature). Therefore low, but not oscillatory, WSS is an early independent marker of atherosclerotic changes preceding intimal thickening at the carotid bulb.

Carotid Artery Wall Thickness and Incident Cardiovascular Events: A Comparison between US and MRI in the Multi-Ethnic Study of Atherosclerosis (MESA)

Purpose To compare common carotid artery (CCA) wall thickness measured manually by using US and semiautomatically by using MRI, and to examine their associations with incident coronary heart disease and stroke. Materials and Methods This prospective study enrolled 698 participants without a history of clinical cardiovascular disease (CVD) from the Multi-Ethnic Study of Atherosclerosis (MESA) from July 2000 to December 2013 (mean age, 63 years; range, 45 to 84 years; same for men and women). All participants provided written informed consent. CCA wall thickness was measured with US as well as both noncontrast proton-density-weighted and intravenous gadolinium-enhanced MRI. Cox proportional hazards models were used to assess the associations between wall thickness measurements by using US and MRI with CVD outcomes. Results The adjusted hazard ratios for coronary heart disease, stroke, and CVD associated with per standard deviation increase in intima-media thickness were 1.10, 1.08, and 1.14, respectively. The corresponding associations for mean wall thickness measured with proton-density-weighted MRI were 1.32, 1.48, and 1.37, and for mean wall thickness measured with gadolinium-enhanced MRI were 1.27, 1.58, and 1.38. When included simultaneously in the same model, MRI wall thickness, but not intima-media thickness, remained associated with outcomes. Conclusion For individuals without known cardiovascular disease at baseline, wall thickness measurements by using MRI were more consistently associated with incident cardiovascular disease, particularly stroke, than were intima-media thickness by using US. © RSNA, 2018 Online supplemental material is available for this article.

Vessel Wall MRI for Targeting Biopsies of Intracranial Vasculitis

Central nervous system vasculitides are elusive diseases that are challenging to diagnose because brain biopsies have high false-negative rates. We sought to test the ability of contrast-enhanced, high-resolution 3D vessel wall MR imaging to identify vascular inflammation and direct open biopsies of intracranial target vessels and adjacent brain parenchyma. Eight of 9 specimens revealed vascular inflammation. We conclude that vessel wall MR imaging can identify inflamed intracranial vessels, enabling precise localization of biopsy targets.

Carotid Intima-Media Thickness and Silent Brain Infarctions in a Biracial Cohort: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Both hypertensive and atherosclerotic processes contribute to common carotid artery intima-media thickness (CCA-IMT). Elevated CCA-IMT may be indicative of subclinical cerebrovascular disease; however, its role in the absence of concomitant carotid artery plaque is uncertain, and few studies have examined associations in Black populations.

MATERIALS AND METHODS

At cohort visit 3 (1993-1995) a subset of stroke-free participants (641 Blacks and 702 Whites, mean age 63) from the Atherosclerosis Risk in Communities (ARIC) study was imaged by brain MRI and carotid ultrasound. A CCA-IMT >0.9 mm was considered elevated. Asymptomatic brain lesions ≥3 mm were considered silent brain infarctions (SBI). Subcortical SBI measuring 3 to <20 mm were considered lacunes. Associations between elevated CCA-IMT and SBI were analyzed with Poisson regression.

RESULTS

Elevated CCA-IMT was identified in 168 participants (16% of Blacks, 10% of Whites), and SBI were observed in 156 (15% of Blacks, 8% of Whites). Elevated CCA-IMT was strongly related to anterior circulation SBI, posterior circulation SBI, and lacunes. After adjustments, elevated CCA-IMT remained associated with greater number of lacunes in Blacks ([prevalence ratio, PR] = 1.60; 95% confidence interval [CI]: 1.02-2.51), but not Whites (PR = 0.85; 95% CI: 0.35-2.04); P value for interaction = 0.12. Among Black participants without concomitant carotid plaque, elevated CCA-IMT was associated with twice the number of lacunes (PR = 2.00; 95% CI: 1.05-3.82).

CONCLUSIONS

In older Black adults, elevated CCA-IMT is independently associated with lipohyalinosis of the cerebral small vessels, irrespective of concomitant carotid plaque and vascular risk factors.

Retinal signs and 20-year cognitive decline in the Atherosclerosis Risk in Communities Study

OBJECTIVE

To test the hypothesis that retinal vascular signs are associated with greater cognitive decline over 20 years in 12,317 men and women 50 to 73 years of age at baseline.

METHODS

A composite cognitive score was created with 3 neuropsychological tests measured at 3 time points (1990-1992 to 2011-2013). Retinal signs were measured with fundus photography (1993-1995). Differences in cognitive change by retinal signs status were estimated with linear mixed models. Cognitive scores were imputed for living participants with incomplete cognitive testing.

RESULTS

In multivariable-adjusted analyses that controlled for attrition, loss of vascular integrity (retinopathy and its components) was associated with greater 20-year decline (difference in 20-year cognitive change for moderate/severe vs no retinopathy -0.53 SD, 95% confidence interval -0.74 to -0.33). Estimated differences were similar in participants with and without diabetes mellitus and in white and black participants.

CONCLUSIONS

Retinopathy was associated with accelerated rates of 20-year cognitive decline. These findings support the exploration of more sensitive measures in the eye such as optical coherence tomography angiography, which may provide surrogate indexes of microvascular lesions relevant to cognitive decline in older adults.

Cognitive impairment and intracranial atherosclerotic stenosis in general population

OBJECTIVE

To investigate the association between asymptomatic intracranial atherosclerosis and cognitive impairment in the Atherosclerosis Risk in Communities (ARIC) cohort.

METHODS

ARIC participants underwent high-resolution 3T magnetic resonance angiography and a neuropsychology battery and neurologic examination adjudicated by an expert panel to detect mild cognitive impairment (MCI) and dementia. We adjusted for demographic and vascular risk factors in weighted logistic regression analysis, accounting for stratified sampling design and attrition, to determine the association of intracranial atherosclerotic stenosis (ICAS) with cognitive impairment.

RESULTS

In 1,701 participants (mean age 76 ± 5.3, 41% men, 71% whites, 29% blacks) with adequate imaging quality and no history of stroke, MCI was identified in 578 (34%) and dementia in 79 (4.6%). In white participants, after adjustment for demographic and vascular risk factors, ICAS ≥50% (vs no ICAS) was strongly associated with dementia (odds ratio [OR] 4.1, 95% confidence interval [CI] 1.7-10.0) and with any cognitive impairment (OR 1.7, 95% CI 1.1-2.8). In contrast, no association was found between ICAS ≥50% and MCI or dementia in blacks, although the sample size was limited and estimates were imprecise.

CONCLUSION

Our results suggest that asymptomatic ICAS is independently associated with cognitive impairment and dementia in whites.

Abstract 151: Intracranial Atherosclerotic Disease and Brain Amyloid Deposition: The ARIC Study

Background: Increasing evidence points to intracranial atherosclerosis as a risk factor not only for stroke but also for dementia, but whether it is linked to Alzheimer’s disease-specific pathology itself is less understood. In the community-based Atherosclerosis Risk in Communities (ARIC) study, we evaluated the cross-sectional association between intracranial atherosclerosis and cerebral amyloid deposition, in nondemented participants.

Methods: In 2011-2014, a subset of participants from the ARIC Neurocognitive Study underwent both a brain MRI, including high-resolution vessel wall imaging, and florbetapir PET, as a marker of amyloid deposition. We analyzed the association between elevated amyloid (defined as a global cortical florbetapir standardized uptake value ratio (SUVR)>1.2) and intracranial arterial plaque presence, frequency, and extent of stenosis, with adjustment for demographic and vascular risk factors. We tested effect modification by APOE ε4 genotype.

Results: In 300 participants (mean age of 76y, 44% African-American, 56% female, 31% carriers of at least one APOE ε4 allele), intracranial plaque was found in 105 (35%) participants. Mean SUVR was higher in individuals with vs without plaque (1.34 ± 0.29 vs 1.27 ± 0.23, p=0.03). In adjusted models, plaque presence was not associated significantly with elevated SUVR in the total sample, nor was number of plaques. Associations between plaque presence and extent were generally stronger in APOE ε4 carriers than noncarriers (p<0.05 for interaction for some plaque features; see Table).

Conclusions: Although intracranial arterial plaque or stenosis was not definitively associated with brain amyloid in this sample of nondemented older adults, associations with brain amyloid appeared stronger in carriers of an APOE ε4 allele, consistent with studies demonstrating a similar relationship as that seen with other more traditionally measured vascular risk factors.

Abstract TMP52: Association of Chronic Kidney Disease and Intracranial Atherosclerotic Disease by High Resolution Vessel Wall MRI: The ARIC Study

Introduction: Chronic kidney disease (CKD) is associated with high risk of cardiovascular disease (CVD), independent of established cardiovascular risk factors, with cystatin C (cysC) demonstrating associations with CVD independent of creatinine-based kidney function. We tested the association between reduced kidney function (eGFR, cysC) and kidney damage (albuminuria) and intracranial atherosclerotic disease (ICAD) by vessel wall MRI (VWMRI) in the ARIC-Neurocognitive (ARIC-NCS) study.

Methods: In this cross-sectional analysis, we sampled ARIC participants with kidney function measurements who completed intracranial VWMRI/MRA. eGFR was estimated by both creatinine and cysC(eGFRcr-cys). Albuminuria was assessed as urinary albumin-creatinine ratio (ACR). Presence and number of intracranial plaques and presence of ≥50% stenosis for individuals with plaques were considered as outcomes in separate multivariable binomial and multinomial logistic models, with adjustment for sociodemographic features, established cardiovascular risk factors, C-reactive protein, and use of antithrombotic and lipid lowering agents.

Results: 1762 participants (age 76.5±5.3) with interpretable MRI and kidney function measurements were included. eGFRcr-cys<60 ml/min/1.73 m 2 (vs≥ 60) was associated with plaque presence(adjusted OR 1.33, 95%CI 1.05-1.68). A similar association between ACR or cysC and plaque presence lost significance in adjusted models (ACR≥30 vs <10: OR 1.19, 95% CI 0.89-1.60; CysC: OR 1.19 for increase by 1 mg/L, 95% CI 0.78-1.82). In adjusted models, compared with eGFRcr-cys≥60 ml/min/1.73 m 2 , participants with eGFRcr-cys<60 had an OR of 1.47 (95% CI 1.1-1.96) for having 1 vs zero plaque, and an OR of 1.23 (95% CI 0.93-1.63) for having ≥2 vs zero plaques. eGFRcr-cys, CysC or ACR were not associated with ≥50% stenosis among those with plaques.

Conclusion: In older adults in the ARIC study, reduced kidney function measured by eGFRcr-cys was independently associated with ICAD burden. The potential mechanism is unknown but may be mediated by decreased clearance of metabolic toxins or proinflammatory cytokines that may play roles in the pathogenesis of atherosclerosis. This finding may help to better identify a high risk population for ICAD.

Abstract TP116: Racial Difference in Intracranial Atherosclerotic Plaque Features by High-resolution Vessel Wall MRI

Introduction: Intracranial atherosclerotic stenosis (ICAS), the most common cause of stroke worldwide, is more prevalent in non-white populations including Asian, African-American and Hispanic individuals. We studied the racial difference (white vs non-white) in the plaque features of stroke patients with ICAS using vessel wall MRI (VWMRI).

Methods: We retrospectively included stroke patients with etiology being intracranial atherosclerosis who received VWMRI. VWMRI was read by experienced neuroradiologists blinded to other clinic information. Culprit plaque was defined as a plaque in a relevant vessel responsible for the downstream ischemic lesion. In addition to plaque number and degree of the stenosis, other plaques features were analyzed, including degree of plaque enhancement(minimal, moderate and strong), plaque calcification and eccentricity. The association between race, cardiovascular risk factors and plaque features was tested in multivariable models.

Results: In 64 stroke patients (mean age 55.6±13.4 y, 62.5% male, 43.8% non-whites), the median number of plaque was 3 (range 0-11). Compared with whites, non-whites have a higher number of plaques (median, 4 vs 3, p=0.029). Smoking was associated with presence of extensive plaque (defined as ≥3 plaques) and remained significant after adjustment for other risks factors (non-white race, hypertension, age≥55 and HbA1C≥6.5; adjusted OR 6.9, 95% CI 1.27-37.66). For culprit plaques, presence of ≥50% stenosis, strong plaque enhancement, eccentric pattern and calcification did not differ by race. LDL >100 mg/dl, history of hyperlipidemia and eGFR<60 mL/min/1.73 m 2 were each associated with presence of strong plaque enhancement, eccentric pattern and calcification respectively (OR 1.5, 95% CI 1.5-19.6; OR 9.9, 95% CI 1.1-85.6; OR 24, 95% CI 2.3-247.4; respectively).

Conclusion: A higher number of intracranial atherosclerotic plaques was revealed by VWMRI in non-white stroke patients with stroke etiology being intracranial atherosclerosis, while the features of their culprit plaque were similar compared with white patients. History of smoking was significantly associated with presence of ≥3 plaques. Studies with larger sample size are needed to validate the above findings.

Carotid Artery Wall Imaging: Perspective and Guidelines from the ASNR Vessel Wall Imaging Study Group and Expert Consensus Recommendations of the American Society of Neuroradiology

Identification of carotid artery atherosclerosis is conventionally based on measurements of luminal stenosis and surface irregularities using in vivo imaging techniques including sonography, CT and MR angiography, and digital subtraction angiography. However, histopathologic studies demonstrate considerable differences between plaques with identical degrees of stenosis and indicate that certain plaque features are associated with increased risk for ischemic events. The ability to look beyond the lumen using highly developed vessel wall imaging methods to identify plaque vulnerable to disruption has prompted an active debate as to whether a paradigm shift is needed to move away from relying on measurements of luminal stenosis for gauging the risk of ischemic injury. Further evaluation in randomized clinical trials will help to better define the exact role of plaque imaging in clinical decision-making. However, current carotid vessel wall imaging techniques can be informative. The goal of this article is to present the perspective of the ASNR Vessel Wall Imaging Study Group as it relates to the current status of arterial wall imaging in carotid artery disease.

Community-based statins and advanced carotid plaque: Role of CD163 positive macrophages in lipoprotein-associated phospholipase A2 activity in atherosclerotic plaque

BACKGROUND AND AIMS

Lipoprotein-associated phospholipase A₂ (Lp-PLA₂), an enzymatic inflammatory biomarker primarily bound to low-density lipoprotein cholesterol, is associated with an approximate twofold increased risk of cardiovascular disease and stroke. Despite indications that circulating Lp-PLA₂ is sensitive to statins, it remains largely unknown whether statin usage exerts local effects on Lp-PLA₂ expression at the site of atheromatous plaque.

METHODS

Carotid plaques (n = 38) were prospectively collected from symptomatic (n = 18) and asymptomatic (n = 20) patients with (n = 20) or without (n = 18) documented statin history. In all cases, endarterectomy was performed where the primary stenosis was removed in an undisturbed manner. Serial cryosections of the presenting lesion were assessed histologically for macrophages, Lp-PLA₂, and cell death (apoptotic index).

RESULTS

Symptomatic lesions exhibited less calcification, with greater inflammation characterized by increased expression of CD68⁺ and CD163⁺ macrophage subsets, and Lp-PLA₂. Symptomatic plaques also exhibited greater necrotic core area and increased apoptosis, as compared with asymptomatic lesions. In contrast, statin treatment did not appear to influence any of these parameters, except for the extent of apoptosis, which was less in statin treated as compared with statin naïve lesions. Overall, Lp-PLA₂ expression correlated positively with necrotic core area, CD68⁺ and CD163⁺ macrophage area, and cell death. Finally, in vitro assays and dual immunofluorescence staining confirmed CD163-expressing monocytes/macrophages are also a major source of Lp-PLA₂.

CONCLUSIONS

Statin treatment has no effect on local atherosclerotic lesion Lp-PLA2 activity, therefore, the addition of anti-inflammatory treatments to further decrease macrophage Lp-PLA₂ expression in atherosclerotic lesions may reduce lesional inflammation and cell death, and prevent necrotic core expansion and lesion progression.

Whole-brain arteriography and venography: Using improved velocity-selective saturation pulse trains

PURPOSE

To develop velocity-selective (VS) MR angiography (MRA) protocols for arteriography and venography with whole-brain coverage.

METHODS

Tissue suppression using velocity-selective saturation (VSS) pulse trains is sensitive to radiofrequency field (B₁ +) inhomogeneity. To reduce its sensitivity, we replaced the low-flip-angle hard pulses in the VSS pulse train with optimal composite (OCP) pulses. Additionally, new pulse sequences for arteriography and venography were developed by placing spatially selective inversion pulses with a delay to null signals from either venous or arterial blood. The VS MRA techniques were compared to the time-of-flight (TOF) MRA in six healthy subjects and two patients at 3T.

RESULTS

More uniform suppression of stationary tissue was observed when the hard pulses were replaced by OCP pulses in the VSS pulse trains, which improved contrast ratios between blood vessels and tissue background for both arteries (0.87 vs. 0.77) and veins (0.80 vs. 0.59). Both arteriograms and venograms depicted all major cervical and intracranial arteries and veins, respectively. Compared to TOF MRA, VS MRA not only offers larger spatial coverage but also depicts more small vessels. Initial clinical feasibility was shown in two patients with comparisons to TOF protocols.

CONCLUSION

Noncontrast-enhanced whole-brain arteriography and venography can be obtained without losing sensitivity to small vessel detection. Magn Reson Med 79:2014-2023, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Intracranial atherosclerosis and dementia: The Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

To explore the association of intracranial atherosclerotic disease (ICAD) with mild cognitive impairment (MCI) and dementia.

METHODS

From 2011 to 2013, 1,744 participants completed high-resolution vessel wall MRI from the population-based Atherosclerosis Risk in Communities Study by a sampling strategy that allowed weighting back to the cohort. We defined ICAD by plaque features (presence, territory, stenosis, number). Trained clinicians used an algorithm incorporating information from interviews and neuropsychological and neurologic examinations to adjudicate for MCI and dementia. We determined the relative prevalence ratio (RPR) of MCI or dementia after adjusting for risk factors at midlife using multinomial logistic regression.

RESULTS

A total of 601 (34.5%) participants had MCI (mean age ± SD, 76.6 ± 5.2 years), 83 (4.8%) had dementia (79.1 ± 5.3 years), and 857 (49.1%) were current or former smokers. Anterior cerebral artery (ACA) plaque (adjusted RPR 3.81, 95% confidence interval [CI] 1.57-9.23), >2 territories with plaque (adjusted RPR 2.12, 95% CI 1.00-4.49), and presence of stenosis >50% (adjusted RPR 1.92, 95% CI 1.01-3.65) were associated with increased prevalence of dementia in separate models. Posterior cerebral artery plaque was associated with MCI but did not reach statistical significance for dementia (adjusted RPR MCI 1.43, 95% CI 1.04-1.98; adjusted RPR dementia 1.58, 95% CI 0.79-2.85). There were no associations with middle cerebral artery atherosclerotic lesions or cognitive impairment. Many participants had plaque in >1 territory (n = 291, 46%) and participants with ACA plaques (n = 69) had the greatest number of plaques in other territories (mean 6.0, SD 4.4).

CONCLUSIONS

This study demonstrates associations between ICAD and clinical MCI and dementia.

Intracranial Vessel Wall MRI: Principles and Expert Consensus Recommendations of the American Society of Neuroradiology

Intracranial vessel wall MR imaging is an adjunct to conventional angiographic imaging with CTA, MRA, or DSA. The technique has multiple potential uses in the context of ischemic stroke and intracranial hemorrhage. There remain gaps in our understanding of intracranial vessel wall MR imaging findings and research is ongoing, but the technique is already used on a clinical basis at many centers. This article, on behalf of the Vessel Wall Imaging Study Group of the American Society of Neuroradiology, provides expert consensus recommendations for current clinical practice.

Polyunsaturated fats, carbohydrates and carotid disease: The Atherosclerosis Risk in Communities (ARIC) Carotid MRI study

BACKGROUND AND AIMS

Carbohydrates and fat intake have both been linked to development of atherosclerosis. We examined associations between glycemic index (GI) and fat intake with carotid atherosclerosis.

METHODS

The Atherosclerosis Risk in Communities (ARIC) cohort enrolled participants during the period 1987-1989 and the Carotid MRI sub-study occurred between 2004 and 2006 (1672 participants attending both visits). Measures of carbohydrate quality (usual GI), fat intake (total, polyunsaturated and saturated) and overall dietary quality index (DASH Diet Score) were derived from a 66-item food frequency questionnaire administered at baseline. Trained readers measured lipid core presence and maximum wall thickness. Using multivariate logistic regression, we determined the odds of lipid core presence by quintile (Q) of energy-adjusted dietary components. Restricted cubic spline models were used to examine non-linear associations between dietary components and maximum wall thickness.

RESULTS

Mean daily polyunsaturated fat intake was 5 g (SD 1.4). GI and polyunsaturated fat intake had a nonlinear relationship with maximum wall thickness. Low (1-4 g) and high (6-12 g) polyunsaturated fat intake were associated with a statistically significant decreased odds of lipid core presence compared to intake in a majority of participants (OR Q5 vs. Q2-4: 0.64, 95% CI 0.42 to 0.98; OR Q1 vs. Q2-4: 0.64, 95% CI 0.42, 0.96), however, the association with lipid core was attenuated by adjustment for maximum wall thickness, hypertension, hyperlipidemia, and diabetes.

CONCLUSIONS

GI and polyunsaturated fat intake were not associated with high-risk plaque features, such as lipid core presence, independent of traditional vascular risk factors.

Prevalence of Intracranial Atherosclerotic Stenosis Using High-Resolution Magnetic Resonance Angiography in the General Population: The Atherosclerosis Risk in Communities Study

BACKGROUND AND PURPOSE

Intracranial atherosclerotic stenosis (ICAS) is a common cause of stroke, but little is known about its epidemiology. We studied the prevalence of ICAS and its association with vascular risk factors using high-resolution magnetic resonance angiography in a US cardiovascular cohort.

METHODS

The Atherosclerosis Risk in Communities (ARIC) study recruited participants from 4 US communities from 1987 to 1989. Using stratified sampling, we selected 1980 participants from visit 5 (2011-2013) for high-resolution 3T-magnetic resonance angiography. All images were analyzed in a centralized laboratory, and ICAS was graded as: no stenosis, <50% stenosis, 50% to 69% stenosis, 70% to 99% stenosis, and complete occlusion. We calculated per-vessel and per-person prevalence of ICAS (weighted for n=6538 visit 5 participants) and also estimated the US prevalence. We used multivariable logistic regression to identify variables independently associated with ICAS.

RESULTS

Subjects who had an adequate magnetic resonance angiography (n=1765) were aged 67 to 90 years, 41% were men, 70% were white, and 29% were black. ICAS was prevalent in 31% of participants and 9% had ICAS ≥50%. Estimated US prevalence of ICAS ≥50% for 65 to 90 years old was 8% for whites and 12% for blacks. Older age, black race, higher systolic blood pressure, and higher low-density lipoprotein cholesterol levels were associated with increased odds of ICAS, whereas higher levels of high-density lipoprotein cholesterol and use of cholesterol-lowering medications were associated with decreased odds of ICAS. Body mass index and smoking were not associated with ICAS.

CONCLUSIONS

The prevalence of ICAS in older adults is high, and it could be a target for primary prevention of stroke and dementia in this population.