A narrative review of plaque and brain imaging biomarkers for stroke risk stratification in patients with atherosclerotic carotid artery disease

Abstract

In this narrative review, we aim to review imaging biomarkers that carry the potential to noninvasively guide stroke risk stratification for treatment optimization.Background: Carotid atherosclerosis plays a fundamental part in the occurrence of ischemic stroke.International guidelines select the optimal treatment strategy still mainly based on the presence of clinical symptoms and the degree of stenosis for stroke prevention in patients with atherosclerotic carotid plaques. These guidelines, based on randomized controlled trials that were conducted three decades ago, recommend carotid revascularization in symptomatic patients with high degree of stenosis versus a conservative approach for most asymptomatic patients. Due to optimization of best medical therapy and risk factor control, it is suggested that a subgroup of symptomatic patients is at lower risk of stroke and may not benefit from revascularization, whereas a selective subgroup of high-risk asymptomatic patients would benefit from this procedure.Methods: A literature search was performed for articles published up to December 2020 using PubMed, EMBASE and Scopus. Based on the literature found, change in stenosis degree and volume, plaque echolucency, plaque surface, intraplaque haemorrhage, lipid-rich necrotic core, thin fibrous cap, inflammation, neovascularization, microembolic signals, cerebrovascular reserve, intracranial collaterals, silent brain infarcts, diffusion weighted imaging lesions and white matters lesions have the potential to predict stroke risk. Conclusions:The applicability of imaging biomarkers needs to be further improved before the potential synergistic prognostic ability of imaging biomarkers can be verified on top of the clinical biomarkers. In the future, the routine and combined assessment of both plaque and brain imaging biomarkers might help to improve optimization of treatment strategies in individual patients with atherosclerotic carotid artery disease.

Correlation of the characteristics of symptomatic intracranial atherosclerotic plaques with stroke types and risk of stroke recurrence: a cohort study

“…Recurrent strokes tend to be more severe and have a worse prognosis than primary strokes, Early identification of patients at high risk of recurrent stroke is important. In previous studies, intracranial atherosclerotic plaque (ICAP) features based on HR-VWI, including positive remodeling, intraplaque hemorrhage, and plaque enhancement, have been shown to be correlated with the recurrence of stroke (10)(11)(12)(13)(14), although conclusions regarding the specific correlations have remained controversial. The characteristics of intracranial arterial culprit plaques based on HR-VWI can provide a basis for differential diagnosis of clinical subtypes of sICAS patients and stratification of risk of stroke recurrence.…”

Patterns and Implications of Intracranial Atherosclerosis in Anterior and Posterior Circulation Identified by High-Resolution Vessel Wall Imaging

“…Our findings may help elucidate the clinical events and outcomes in anterior and posterior circulation stroke. Plaque hypo-intensity in ICAS serves as an imaging biomarker of intraplaque lipid core, and plaque contrast enhancement as intraplaque inflammation and neovascularization [19,20]. Both plaque imaging features provide potential clues to vulnerable plaques at high risk for rupture and future vascular ischemia [20,22,23].…”

“…The enhancement index (EI) was calculated as follows: EI = ([SI plaque / SI gray matter on post-contrast T1w images] -[SI plaque /SI gray matter on precontrast T1w images])/(SI plaque /SI gray matter on pre-contrast T1w images) × 100% [11]. Plaque contrast enhancement was shown in strong association with intraplaque inflammation and neovascularization [20]. Vessels with stenotic degrees over 30% on HR-VWI were identified on the matched TOF-MRA and visually classified into normal, irregular (undulating lesion surface lining), stenotic, and occluded [21].…”

Advances in Noninvasive Carotid Wall Imaging with Ultrasound: A Narrative Review

“…The use of carotid plaque hypo-echogenicity as a risk stratification biomarker for predicting the annual risk for cerebrovascular ischemic events (stroke, TIA, amaurosis fugax) is supported by histopathologic studies showing that echolucent plaques mostly consist of lipid-rich necrotic cores (and/or) and intraplaque hemorrhage [ 15 ]. A meta-analysis involving 7557 asymptomatic patients followed for more than 3 years, demonstrated that plaques described as echolucent, showing intraplaque neovascularization and ulceration were associated with twice the risk of ischemic symptoms compared to stable echogenic plaques [ 16 ].…”