If you don't remember your password, you can reset it by entering your email address and clicking the Reset Password button. You will then receive an email that contains a secure link for resetting your password
If the address matches a valid account an email will be sent to __email__ with instructions for resetting your password
Symptomatic MCA plaques were significantly associated with T1 hyperintensity
•
Plaque enhancement was statistically significantly associated with symptomatic MCA plaques
•
VWI has become a potential noninvasive vascular imaging tool for the management of intracranial atherosclerotic plaques
Abstract
Objective
A comprehensive understanding of atherosclerotic middle cerebral artery (MCA) plaques aids physicians in diagnosis and treatment of ischemic stroke. High-resolution magnetic resonance imaging (MRI) has been used to identify imaging biomarkers of symptomatic MCA plaque. We performed this systematic review and meta-analysis to evaluate which characteristics of MCA plaque are markers of culprit lesions.
Materials and methods
The PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched for publications up to March 2022. Two independent reviewers extracted data on study design, high-resolution MRI parameters, and imaging end points. Odds ratios (ORs) for the prevalence of stroke with atherosclerotic MCA plaque features were pooled in the meta-analysis by using a random-effects model. Subgroup analysis, sensitivity analysis, and evaluation of publication bias were also conducted.
Results
Seventeen articles were included in this review. Symptomatic MCA plaques were significantly associated with contrast enhancement (OR, 9.4; 95 % CI, 4.3–20.4) and T1 hyperintensity (OR, 6.2; 95 % CI, 2.7–14.3). However, there was no association between symptomatic plaques and T2 hyperintensity (OR, 1.4; 95 % CI, 0.8–2.3). Plaque enhancement was significantly associated with downstream ischemic events in subgroup analyses based on different study designs and MR sequence types.
Conclusion
Based on current evidence, contrast enhancement and T1 hyperintensity on high-resolution MRI have high potential as imaging biomarkers of patients with MCA plaques at risk of ischemic events. Future prospective, longitudinal studies of intracranial-plaque high-resolution MRI are required to improve decision-making for the management of intracranial atherosclerotic plaques.
Prevalence and outcomes of symptomatic intracranial large artery stenoses and occlusions in China: the chinese intracranial atherosclerosis (CICAS) study.
Postmortem study of validation of low signal on fat-suppressed T1-weighted magnetic resonance imaging as marker of lipid Core in middle cerebral artery atherosclerosis.
In addition, patients with symptomatic MCA stenosis in one study had an overall stroke risk of 12.5% per year, compared to that of only 2.85% in patients with asymptomatic MCA disease.
However, accumulating evidence suggests that stenotic grade does not really differ between symptomatic and asymptomatic groups of patients with moderate to severe MCA stenosis.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
Meanwhile, high-resolution magnetic resonance imaging (hr-MRI) has emerged as a novel diagnostic tool to assess both the coronary and extracranial carotid stenosis.
However, VWI is not yet as commonly used for MCA stenosis owing to technical limitations in the imaging of small structures and the lack of in vivo histological results for comparison.
To successfully image the intracranial vessel wall, the black blood technique was used by suppressing the MRI signal arising from luminal blood and cerebrospinal fluid (CSF) to obtain a high contrast-to-noise ratio (CNR). Blood and CSF suppression may be attained using spin-echo imaging, pre-regional saturation pulse, or a double-inversion recovery-based sequence.
Recently, numerous imaging studies on MCA plaques have been published, suggesting that, in addition to the degree of stenosis, radiological characteristics may be an important predictor of plaque vulnerability.
As many of the studies had small sample sizes and as the relationship between MCA plaque morphology and the risk of stroke is unclear, we performed this meta-analysis to quantitatively synthesize existing evidence and evaluate the strengths of association of commonly investigated imaging features of symptomatic MCA plaques.
2. Materials and methods
This study was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.
Institutional Review Board approval and written informed consent were not required because this study was retrospective. This protocol is registered on PROSPERO (registration number is CRD42022316417).
2.1 Literature search strategy
The PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched for publications up to March 2022. The following search terms were used in relevant combinations using the Boolean operators “OR” and “AND”: “middle cerebral artery,” “plaque, atherosclerotic,” “magnetic resonance imaging,” “high resolution,” and “gadolinium contrast” (Supplemental material: Search Strategy). In addition, we screened the reference lists of the included articles for further relevant studies.
2.2 Eligibility criteria
Two researchers independently screened studies, and disagreements were resolved by consensus. Inclusion criteria were as follows: (1) studies in which patients with atherosclerotic stenosis of the MCA were recruited; (2) studies in which patients who underwent hr-MRI of the MCA were included; and (3) studies in which imaging features were compared between symptomatic and asymptomatic atherosclerotic plaques of the MCA. We excluded studies in which (1) there was insufficient raw data, (2) duplicate data were reported, (3) only continuous variables were assessed as imaging end points, (4) <10 participants were included, and that (5) were cohort studies, conference abstracts, or letters.
2.3 Quality assessment
The quality of the selected studies was independently evaluated by two investigators using the “Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies,” provided by the National Institutes of Health.
Two reviewers independently extracted data from the eligible studies, and discrepancies were resolved by consensus. The following data were collected: study characteristics (e.g., first author's name, public-cation year, patient enrollment design, country in which the study was conducted, demographic data, and prevalence of stroke risk factors), MRI protocols (e.g., MR scanner, magnetic field strength, coil type, hr-MRI sequences, and certain sequence parameters), and MRI analysis (e.g., reader characteristics, imaging end point criteria).
2.5 Statistical analysis
Demographic characteristics and extracted variables were described using standard descriptive statistics. Categorical variables were expressed as frequencies and percentages, and continuous variables were expressed as means with standard deviations.
In the present meta-analysis, the association between the ischemic event and the plaque imaging feature was measured by estimating the odds ratios (ORs) and corresponding 95 % confidence intervals (CIs). Pooled ORs for dichotomous variables were estimated using a random-effects (DerSimonian-Laird) model with the assumption that individual studies did not have the same effect size. Forest plots were generated when the imaging feature of interest was present in at least three studies. These included plaque T1 hyperintensity, T2 hyperintensity, contrast enhancement, eccentricity, and positive remodeling. In order to calculate ORs for studies in which the degree of contrast enhancement was classified with a three-level grading system (0: enhancement was less than or equal to that of intracranial arterial walls without plaque, 1: less enhancement than the pituitary stalk, 2: enhancement greater than or equal to that of the pituitary stalk), we dichotomized the three-level grading system as negative (grade 0) and positive (grade 1 to 2). A continuity correction of 0.5 was applied to studies with zero cell frequencies.
Heterogeneity among studies was tested using I2 statistics,
with values higher than 50% considered to indicate substantial heterogeneity. We explored factors that may account for heterogeneity by conducting subgroup analysis according to any binary variables that may have affected the consistency of a result across the enrolled studies. We further conducted sensitivity analysis with the “leave-one-out” method to assess the robustness of the results. Publication bias was assessed with a funnel plot and Egger's test; a P-value < 0.05 was considered to indicate publication bias.
All statistical analyses were implemented using STATA statistical software: release 16 (StataCorp LLC, College Station, TX).
3. Results
3.1 Literature search
A flow chart summarizing the literature search is presented in Fig. 1. A total of 543 studies were identified during the initial search, of which 53 were selected after title and abstract screening. After reviewing the full texts, 17 studies met the inclusion criteria for our systematic review.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
The relationship between patterns of remodeling and degree of enhancement in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study.
A high-resolution MRI study of relationship between remodeling patterns and ischemic stroke in patients with atherosclerotic middle cerebral artery stenosis.
Plaque distribution and characteristics in low-grade middle cerebral artery stenosis and its clinical relevance: a 3-dimensional high-resolution magnetic resonance imaging study.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
rated “good” or “fair.” As all the included studies were cross-sectional analyses, the answer to Questions 5–7 of the assessment guidance was “no.”
3.3 Characteristics of included studies
The basic demographic data and the prevalence of risk factors of the 17 studies are summarized in Table 1. In total, 1192 MCA atherosclerotic plaques of 1165 patients were eligible for the meta-analysis. The 17 included studies were all based on the Asian population: 16 were from China
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
The relationship between patterns of remodeling and degree of enhancement in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study.
A high-resolution MRI study of relationship between remodeling patterns and ischemic stroke in patients with atherosclerotic middle cerebral artery stenosis.
Plaque distribution and characteristics in low-grade middle cerebral artery stenosis and its clinical relevance: a 3-dimensional high-resolution magnetic resonance imaging study.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
The relationship between patterns of remodeling and degree of enhancement in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study.
A high-resolution MRI study of relationship between remodeling patterns and ischemic stroke in patients with atherosclerotic middle cerebral artery stenosis.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
Plaque distribution and characteristics in low-grade middle cerebral artery stenosis and its clinical relevance: a 3-dimensional high-resolution magnetic resonance imaging study.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
A high-resolution MRI study of relationship between remodeling patterns and ischemic stroke in patients with atherosclerotic middle cerebral artery stenosis.
Plaque distribution and characteristics in low-grade middle cerebral artery stenosis and its clinical relevance: a 3-dimensional high-resolution magnetic resonance imaging study.
The relationship between patterns of remodeling and degree of enhancement in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
The relationship between patterns of remodeling and degree of enhancement in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study.
A high-resolution MRI study of relationship between remodeling patterns and ischemic stroke in patients with atherosclerotic middle cerebral artery stenosis.
Plaque distribution and characteristics in low-grade middle cerebral artery stenosis and its clinical relevance: a 3-dimensional high-resolution magnetic resonance imaging study.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
A high-resolution MRI study of relationship between remodeling patterns and ischemic stroke in patients with atherosclerotic middle cerebral artery stenosis.
Plaque distribution and characteristics in low-grade middle cerebral artery stenosis and its clinical relevance: a 3-dimensional high-resolution magnetic resonance imaging study.
The relationship between patterns of remodeling and degree of enhancement in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
Plaque distribution and characteristics in low-grade middle cerebral artery stenosis and its clinical relevance: a 3-dimensional high-resolution magnetic resonance imaging study.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
in the meta-analyzed for plaque contrast enhancement and T1 hyperintensity, respectively. Symptomatic plaques were significantly associated with contrast enhancement (OR, 9.4; 95 % CI, 4.3–20.4; I2 = 49.3%; P < 0.001) and T1 hyperintensity (OR, 6.2; 95 % CI, 2.7–14.3; I2 = 10.7%; P < 0.001) (Fig. 2A, B).
Fig. 2Forest plots of imaging features of symptomatic plaque. Forest plots of pooled data are graphically shown for 3 imaging features. Squares represent point estimates of a study's effect size and their sizes are proportional to the sample sizes. Horizontal lines show the corresponding 95 % confidence intervals (CIs). The vertical line represents an odds ratio of 1 (no effect). Diamonds represent pooled estimates with the diamond width representing 95 % CIs.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
Plaque distribution and characteristics in low-grade middle cerebral artery stenosis and its clinical relevance: a 3-dimensional high-resolution magnetic resonance imaging study.
provided data that were eligible for the meta-analysis. Symptomatic plaques were not significantly associated with T2 hyperintensity (OR, 1.4; 95 % CI, 0.8–2.3; I2 = 0%; P = 0.19) (Fig. 2C).
The relationship between patterns of remodeling and degree of enhancement in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study.
A high-resolution MRI study of relationship between remodeling patterns and ischemic stroke in patients with atherosclerotic middle cerebral artery stenosis.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
studies were meta-analyzed for eccentricity and positive remodeling, respectively. However, the results were not pooled because we observed significant heterogeneity in the analysis.
3.5 Subgroup analyses and sensitivity analysis
Because plaque contrast enhancement was the most frequently studied imaging feature (n = 8 studies) and the pooled results had a moderate heterogeneity (I2 = 49.3%), subgroup analysis was performed based on the (1) patient enrollment design (retrospective vs. prospective), (2) MRI sequence type (2D vs. 3D), and (3) grading scheme of the degree of contrast enhancement (two vs. three levels).
Plaque enhancement had a significantly higher (P < 0.001) association with downstream ischemic events in retrospective studies (OR, 12.4; 95 % CI, 3.2–47.7) than in prospective studies (OR, 8.5; 95 % CI, 3.7–19.9). The association was also significantly higher (P < 0.001) when a two-level grading system was employed to evaluate enhancement (OR, 15.6; 95 % CI, 2.6–93.6) than when a three-level grading system was used (OR, 7.6; 95 % CI, 3.1–18.6). The strength of the association did not differ based on MRI sequence type for plaque enhancement (P = 0.56) (Table 3).
Table 3Results of subgroup analyses of contrast enhancement of symptomatic plaque.
Category
Subgroup
Studies no.
Odds ratio (95 % CI)
I2 (%)
P value
Subject enrollment design
Retrospective enrollment
5
12.4 (3.2, 47.7)
68.9
<0.001
Prospective enrollment
3
8.5 (3.7, 19.9)
0
MR sequence type
2D sequence
4
12.0 (3.9, 37.2)
63.7
0.56
3D sequence
4
7.4 (2.0, 27.0)
44.5
Degree of contrast enhancement
Two grading
3
15.6 (2.6, 93.6)
75.5
<0.001
Three grading
5
7.6 (3.1–18.6)
29.2
MR, magnetic resonance; no., number; CI, confidence interval.
It is important to improve the diagnostic confidence that an MCA atherosclerotic plaque is the cause of a patient's ischemic stroke because it can help guide effective stroke prevention and treatment strategies. Our results indicate that MCA plaques with contrast enhancement and T1 hyperintensity are related to downstream ischemia. Unlike two previously published meta-analyses,
T1 hyperintensity of hr-MRI may be due to both recent and fresh intraplaque hemorrhages (IPH). IPH is mostly attributed to fragile and leaky neovascularity with endothelial disruption and large local deformation.
A meta-analysis revealed that T1 hyperintensity is a reliable predictor of subsequent stroke or transient ischemic attack for patients with extracranial carotid plaques.
In our meta-analysis, T1 hyperintensity was more common in patients with symptomatic atherosclerotic stenosis than in those with asymptomatic plaques, which suggests that MCA atherosclerosis may share a common potential pathophysiology with carotid atherosclerosis. A major limitation to the use of T1 hyperintensity in intracranial plaques is that it has a low prevalence at the site of the stenosis due to the small size and deep location of the target vessel.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
improved the T1 hyperintensity rates in symptomatic MCA stenoses to 30% and 55.6%, respectively, using 3D sequences.
Plaque contrast enhancement, being a very attractive imaging marker of plaque vulnerability in both extracranial and intracranial arteries, is thought to be related to active inflammation, neovascularity, and increased endothelial permeability.
In our study, plaque enhancement was statistically significantly associated with symptomatic MCA plaques, and some of the included studies revealed that such enhancement may be independent of the degree of stenosis. Infarction was approximately 10 times more likely to occur in patients with an enhancing MCA stenosis than in those with a non-enhancing MCA stenosis.
In the subgroup analysis for the patient enrollment design, the association between contrast enhancement and symptomatic plaques was higher for retrospective studies than for prospective studies, which may be because of selection bias. The association was also higher in studies in which a two-level grading system was used rather than a three-level grading system, probably because of increased measurement variability. Finally, although the strength of the association did not differ between studies in which 2D-sequences were used and those in which 3D-sequences were used, there was an increased association between plaque enhancement and symptomatic plaques in studies in which 2D-sequences were used. A possible explanation is that a relatively low spatial resolution may be sufficient to detect enhancement of a lesion as a result of an increase in CNR caused by the contrast uptake.
In addition, Balu et al revealed that 3D-sequences improve small plaque component visualization of the carotid artery, while providing poor image quality caused by motion artifacts.
Images in cardiovascular medicine. Detection of carotid atherosclerotic plaque ulceration, calcification, and thrombosis by multicontrast weighted magnetic resonance imaging.
Differentiation of intraplaque versus juxtaluminal hemorrhage/thrombus in advanced human carotid atherosclerotic lesions by in vivo magnetic resonance imaging.
In our study, T2 hyperintensity was not seen to be significantly associated with symptomatic plaques, which suggests that the T2 hyperintensity alone may not be a high-risk imaging biomarker.
4.1 Limitations
There are several limitations to this study. First, most of the included studies had small sample sizes, with limited power for subgroup analyses. Second, all included studies were from Asian populations, which may cause publication bias. This is because ICAS accounts for 30–50% and 10% of ischemic cerebrovascular events in Asian and Western populations, respectively.
Increasing severity of cardiovascular risk factors with increasing middle cerebral artery stenotic involvement in type 2 diabetic chinese patients with asymptomatic cerebrovascular disease.
Third, the wide CIs suggest low statistical power, leading to imprecise effect estimates. Finally, different methodologies were used in the included studies. Although the statistical analysis of heterogeneity in effect sizes showed homogeneity among studies, the methodological diversity may have led to misinterpretation of the pooled estimates.
5. Conclusion
In this study, by pooling the available evidence, we identified two imaging markers for symptomatic MCA plaques: contrast enhancement and plaque T1 hyperintensity. These imaging features may help clinicians to improve patient diagnosis and treatment decisions. Future prospective, longitudinal studies of patients with ischemia are required to validate the utility of these imaging features as predictive markers.
Declaration of competing interest
None.
Acknowledgments
This work was supported by the National Natural Science Foundation of China [grant numbers 81860222 , 82060226 , 81960220 ]; and the Natural Science Foundation of Guangxi Province [grant numbers 2019GXNSFDA185008 , 2019GXNSFAA185029 ].
Prevalence and outcomes of symptomatic intracranial large artery stenoses and occlusions in China: the chinese intracranial atherosclerosis (CICAS) study.
Postmortem study of validation of low signal on fat-suppressed T1-weighted magnetic resonance imaging as marker of lipid Core in middle cerebral artery atherosclerosis.
An assessment on the incremental value of high-resolution magnetic resonance imaging to identify culprit plaques in atherosclerotic disease of the middle cerebral artery.
The relationship between patterns of remodeling and degree of enhancement in patients with atherosclerotic middle cerebral artery stenosis: a high-resolution MRI study.
A high-resolution MRI study of relationship between remodeling patterns and ischemic stroke in patients with atherosclerotic middle cerebral artery stenosis.
Plaque distribution and characteristics in low-grade middle cerebral artery stenosis and its clinical relevance: a 3-dimensional high-resolution magnetic resonance imaging study.
MRI of plaque characteristics and relationship with downstream perfusion and cerebral infarction in patients with symptomatic middle cerebral artery stenosis.
Images in cardiovascular medicine. Detection of carotid atherosclerotic plaque ulceration, calcification, and thrombosis by multicontrast weighted magnetic resonance imaging.
Differentiation of intraplaque versus juxtaluminal hemorrhage/thrombus in advanced human carotid atherosclerotic lesions by in vivo magnetic resonance imaging.
Increasing severity of cardiovascular risk factors with increasing middle cerebral artery stenotic involvement in type 2 diabetic chinese patients with asymptomatic cerebrovascular disease.