The Protective Effect of Middle Cerebral Artery Calcification on Symptomatic Middle Cerebral Artery Infarction

CT texture analysis of vertebrobasilar artery calcification to identify culprit plaques

Objectives

The aim of this study was to extract radiomic features from vertebrobasilar artery calcification (VBAC) on head computed tomography (CT) images and investigate its diagnostic performance to identify culprit lesions responsible for acute cerebral infarctions.

Methods

Patients with intracranial atherosclerotic disease who underwent vessel wall MRI (VW-MRI) and head CT examinations from a single center were retrospectively assessed for VBAC visual and textural analyses. Each calcified plaque was classified by the likelihood of having caused an acute cerebral infarction identified on VW-MRI as culprit or non-culprit. A predefined set of texture features extracted from VBAC segmentation was assessed using the minimum redundancy and maximum relevance method. Five key features were selected to integrate as a radiomic model using logistic regression by the Aikaike Information Criteria. The diagnostic value of the radiomic model was calculated for discriminating culprit lesions over VBAC visual assessments.

Results

A total of 1,218 radiomic features were extracted from 39 culprit and 50 non-culprit plaques, respectively. In the VBAC visual assessment, culprit plaques demonstrated more observed presence of multiple calcifications, spotty calcification, and intimal predominant calcification than non-culprit lesions (all p < 0.05). In the VBAC texture analysis, 55 (4.5%) of all extracted features were significantly different between culprit and non-culprit plaques (all p < 0.05). The radiomic model incorporating 5 selected features outperformed multiple calcifications [AUC = 0.81 with 95% confidence interval (CI) of 0.72, 0.90 vs. AUC = 0.61 with 95% CI of 0.49, 0.73; p = 0.001], intimal predominant calcification (AUC = 0.67 with 95% CI of 0.58, 0.76; p = 0.04) and spotty calcification (AUC = 0.62 with 95% CI of 0.52, 0.72; p = 0.005) in the identification of culprit lesions.

Conclusion

Culprit plaques in the vertebrobasilar artery exhibit distinct calcification radiomic features compared to non-culprit plaques. CT texture analysis of VBAC has potential value in identifying lesions responsible for acute cerebral infarctions, which may be helpful for stroke risk stratification in clinical practice.

Intracranial Spotty Calcium Predicts Recurrent Stroke in Patients with Symptomatic Intracranial Atherosclerotic Stenosis : A Prospective Cohort Study

PURPOSE

Accumulating evidence highlights the association of calcium characteristics and cardiovascular events, but its role in cerebrovascular stenosis has not been well studied. We aimed to investigate the contribution of calcium patterns and density to recurrent ischemic stroke in patients with symptomatic intracranial atherosclerotic stenosis (ICAS).

METHODS

In this prospective study, 155 patients with symptomatic ICAS in the anterior circulation were included, and all subjects underwent computed tomography angiography. The median follow-up for all patients was 22 months and recurrent ischemic stroke were recorded. Cox regression analysis was performed to examine whether calcium patterns and density were associated with recurrent ischemic stroke.

RESULTS

During the follow-up, 29 patients who experienced recurrent ischemic stroke were older than those without recurrent ischemic stroke (62.93 ± 8.10 years vs. 57.00 ± 12.07 years, p = 0.027). A significantly higher prevalence of intracranial spotty calcium (86.2% vs. 40.5%, p < 0.001) and very low-density intracranial calcium (72.4% vs. 37.3%, p = 0.001) were observed in patients with recurrent ischemic stroke. Multivariable Cox regression analysis showed that intracranial spotty calcium, rather than very low-density intracranial calcium, remained an independent predictor of recurrent ischemic stroke (adjusted hazard ratio 5.35, 95% confidence interval 1.32-21.69, p = 0.019).

CONCLUSION

In patients with symptomatic ICAS, intracranial spotty calcium is an independent predictor of recurrent ischemic stroke, which will further facilitate risk stratification and suggest that more aggressive treatment should be considered for these patients.

Intimal predominant calcification is associated with plaque instability in the vertebrobasilar artery by vessel wall magnetic resonance imaging and computed tomography

BACKGROUND AND AIMS

It remains unknown about the relationship between vertebrobasilar artery (VBA) calcification and plaque instability. We aimed to investigate the characteristics of VBA calcification using vessel wall magnetic resonance imaging (MRI) and computed tomography (CT) and its association with acute cerebral infarction (ACI).

METHODS

Nine hundred and thirty patients with VBA stenosis who underwent vessel wall MRI and CT examinations were evaluated retrospectively. Calcification morphology was classified as either intimal or non-intimal predominant using a CT-pathology-validated grading method. Qualitative and quantitative plaque MRI variables and calcification characteristics were compared between culprit and non-culprit lesions. The association between VBA calcification and the occurrence of culprit lesions was investigated using multivariate logistic regression.

RESULTS

A total of 150 patients with ACI and 142 patients without ACI were eligible for subsequent analyses, respectively. In the qualitative analysis, T1 hyperintensity (p < 0.001) and intimal predominant calcification (p = 0.021) were more frequently observed in the culprit than non-culprit lesions. In the quantitative analyses, culprit lesions had a larger stenosis degree, plaque length, normal wall index, contrast enhancement ratio, lower calcification density and smaller calcification volume than non-culprit lesions (p all < 0.05). Intimal predominant calcification (odds ratio [OR], 2.51; 95 % confident interval [CI], 1.31-4.82, p = 0.006) and calcification density (OR, 0.53; 95 % CI, 0.35-0.78, p = 0.001) were independently associated with the presence of ACI after adjusting for clinical risk factors and plaque variables.

CONCLUSIONS

Intimal predominant calcification in vertebrobasilar atherosclerosis is associated with the likelihood of having caused acute cerebral infarction. The morphology and density of VBA calcification may provide insight into stroke risk stratification in the posterior circulation.

Arterial Calcification and Its Association With Stroke: Implication of Risk, Prognosis, Treatment Response, and Prevention

Stroke is a leading cause of death worldwide. Vascular calcification (VC), defined as deposition of calcium-phosphate complexes in the vessels, is considered as the characteristic of vascular aging. Calcifications at different vessel layers have different implications. Intimal calcification is closely related to atherosclerosis and affects plaque stability, while medial calcification can cause arterial stiffening and reduce compliance. Accumulating evidence suggested that arterial calcifications, including calcifications in the intracranial artery, coronary artery, and carotid artery, are associated with the risk, prognosis, and treatment response of stroke. VC can not only serve as a marker of atherosclerosis, but cause cerebral hemodynamic impairment. In addition, calcifications in large arteries are associated with cerebral small vessel disease. In this review, we summarize the findings of recently published studies focusing on the relationship between large artery calcification and the risk, prognosis, treatment response, and prevention of stroke and also discuss possible mechanisms behind those associations.

Intracranial Arterial Calcification and Intracranial Atherosclerosis: Close but Different

Background and Purpose

Intracranial arterial calcification (IAC) may be present in the intimal or medial arterial layer. This study aimed to elucidate the link between the calcification and atherosclerotic disease in the intracranial vasculature.

Methods

Consecutive patients with acute ischemic stroke were included. Bilateral intracranial segment of the internal carotid artery, M1 segment of the middle cerebral artery, intracranial segment of the vertebral artery, and the basilar artery were visualized by the multi-detector computed tomography (CT) and vessel-wall magnetic resonance imaging (vwMRI) within 14 days after stroke onset. IAC was into the intimal or medial pattern. Subsequently, on the vwMRI, we assessed the luminal stenosis, eccentricity, plaque burden, and intraplaque hemorrhage (IPH) as markers of atherosclerosis at each IAC site.

Results

Among 69 patients with stroke, IAC was identified in 35% of (161/483) artery segments, of which 61.5% were predominantly intimal calcification and 38.5% were predominantly medial calcification. About 79.8% of intimal calcifications and 64.5% of medial calcifications co-existed with atherosclerotic plaques. Intimal calcification was associated with luminal stenosis (p = 0.003) caused by atherosclerotic lesions. Compared with the medial IAC, intimal IAC was more often accompanied by eccentric plaques (p = 0.02), larger plaque burden (p = 0.001), and IPH (p = 0.001).

Conclusion

Our multimodal imaging-based comparison study on intracranial arteriosclerosis demonstrated that intimal IAC, compared with medial IAC, was more often accompanied by the luminal stenosis, larger plaque burden, eccentricity, and IPH, providing strong evidence for clinical evaluation on the mechanism, risk, and prognosis of ischemic stroke.

Histology-Verified Intracranial Artery Calcification and Its Clinical Relevance With Cerebrovascular Disease

Intracranial artery calcification (IAC) was regarded as a proxy for intracranial atherosclerosis (ICAS). IAC could be easily detected on routine computer tomography (CT), which was neglected by clinicians in the previous years. The evolution of advanced imaging technologies, especially vessel wall scanning using high resolution-magnetic resonance imaging (HR-MRI), has aroused the interest of researchers to further explore the characteristics and clinical impacts of IAC. Recent histological evidence acquired from the human cerebral artery specimens demonstrated that IAC could mainly involve two layers: the intima and the media. Accumulating evidence from histological and clinical imaging studies verified that intimal calcification is more associated with ICAS, while medial calcification, especially the internal elastic lamina, contributes to arterial stiffness rather than ICAS. Considering the highly improved abilities of novel imaging technologies in differentiating intimal and medial calcification within the large intracranial arteries, this review aimed to describe the histological and imaging features of two types of IAC, as well as the risk factors, the hemodynamic influences, and other clinical impacts of IAC occurring in intimal or media layers.

Intracranial Arterial Calcification: Prevalence, Risk Factors, and Consequences: JACC Review Topic of the Week

Intracranial large and small arterial calcifications are a common incidental finding on computed tomography imaging in the general population. Here we provide an overview of the published reports on prevalence of intracranial arterial calcifications on computed tomography imaging and histopathology in relation to risk factors and clinical outcomes. We performed a systematic search in Medline, with a search filter using synonyms for computed tomography scanning, (histo)pathology, different intracranial arterial beds, and calcification. We found that intracranial calcifications are a frequent finding in all arterial beds with the highest prevalence in the intracranial internal carotid artery. In general, prevalence increases with age. Longitudinal studies on calcification progression and intervention studies are warranted to investigate the possible causal role of calcification on clinical outcomes. This might open up new therapeutic directions in stroke and dementia prevention and the maintenance of the healthy brain.

Understanding the Clinical Implications of Intracranial Arterial Calcification Using Brain CT and Vessel Wall Imaging

Background and Purpose: Intracranial arterial calcification (IAC) has been the focus of much attention by clinicians and researchers as an indicator of intracranial atherosclerosis, but correlations of IAC patterns (intimal or medial) with the presence of atherosclerotic plaques and plaque stability are still a matter of debate. Our study aimed to assess the associations of IAC patterns identified on computed tomography (CT) with the presence of plaque detected on vessel wall magnetic resonance imaging and plaque stability. Materials and Methods: Patients with stroke or transient ischemic attack and intracranial artery stenosis were recruited. IAC was detected and localized (intima or media) on non-contrast CT images. Intracranial atherosclerotic plaques were identified using vessel wall magnetic resonance imaging and matched to corresponding CT images. Associations between IAC patterns and culprit atherosclerotic plaques were assessed by using multivariate regression. Results: Seventy-five patients (mean age, 63.4 ± 11.6 years; males, 46) were included. Two hundred and twenty-one segments with IAC were identified on CT in 66 patients, including 86 (38.9%) predominantly intimal calcifications and 135 (61.1%) predominantly medial calcifications. A total of 72.0% of intimal calcifications coexisted with atherosclerotic plaques, whereas only 10.2% of medial calcifications coexisted with plaques. Intimal calcification was more commonly shown in non-culprit plaques than culprit plaques (25.9 vs. 9.4%, P = 0.008). The multivariate mixed logistic regression adjusted for the degree of stenosis showed that intimal calcification was significantly associated with non-culprit plaques (OR, 2.971; 95% CI, 1.036-8.517; P = 0.043). Conclusion: Our findings suggest that intimal calcification may indicate the existence of a stable form of atherosclerotic plaque, but plaques can exist in the absence of intimal calcification especially in the middle cerebral artery.