Progression of Plaque Burden of Intracranial Atherosclerotic Plaque Predicts Recurrent Stroke/Transient Ischemic Attack: A Pilot Follow-Up Study Using Higher-Resolution MRI

High-risk characteristics of recurrent ischemic stroke after intensive medical management for 6-month follow-up: a histogram study on vessel wall MRI

OBJECTIVE

Intensive medical management has been recommended for ischemic stroke of intracranial atherosclerosis (ICAS), but 9.4-15% probability of recurrent stroke remains an inevitable reality. The characteristics of high-risk intracranial plaque that contribute to stroke recurrence after intensive therapy are unclear.

METHODS

The patients of acute ischemic stroke due to ICAS from two centers were prospectively analyzed, who underwent the 3D high-resolution head and neck vessel wall magnetic resonance imaging (hr-VW-MRI) at baseline and received intensive medical management within 90 days. The morphological features, such as minimal lumen area (MLA), and histogram parameters including entropy were assessed based on hr-VW-MR images. The recurrence of ischemic events after 6 months was defined as hyperintensity on diffusion-weighted images in the ipsilateral vascular territory. Cox regression analysis was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for recurrent events.

RESULTS

A total of 222 patients (age 59.5 ± 12.1; males 153) were finally included, and 38 had recurrent stroke after 6 months. After adjusting the age and gender, Cox regression demonstrated that smoking (HR = 4.321; 95% CI, 1.838-10.161; p = 0.001), taking exercise (HR = 0.409; 95% CI, 0.198-0.843; p = 0.015), blood pressure management (HR = 0.180; 95% CI, 0.073-0.443; p = 0.001), MLA (HR = 0.771; 95% CI, 0.625-0.951; p = 0.015) and entropy (HR = 0.274; 95% CI, 0.130-0.576; p = 0.001) were significant predictors of recurrent ischemic stroke. However, the area under curve value of MRI parameters was significantly higher than that of traditional clinical factors (0.86 vs 0.79; p = 0.01).

CONCLUSIONS

The plaque characteristics based on hr-VW-MRI may provide complementary values over traditional clinical features in predicting ischemic recurrence for ICAS.

KEY POINTS

Question The study addresses recurrent ischemic stroke in intracranial atherosclerosis patients, identifying high-risk plaque features that contribute to recurrence despite intensive medical management. Findings Plaque features on high-resolution vessel wall magnetic resonance imaging (hr-VW-MRI), such as minimal lumen area and entropy, improve prediction of stroke recurrence over clinical factors. Clinical relevance This two-center prospective study improves patient care by using hr-VW-MRI and histogram factors like entropy to better predict stroke recurrence, allowing for more personalized treatment strategies and potentially reducing ischemic events in patients with intracranial atherosclerosis.

Comprehensive imaging analysis of intracranial atherosclerosis

Intracranial atherosclerotic disease (ICAD) involves the build-up of atherosclerotic plaques in cerebral arteries, significantly contributing to stroke worldwide. Diagnosing ICAD entails various techniques that measure arterial stenosis severity. Digital subtraction angiography, CT angiography, and magnetic resonance angiography are established methods for assessing stenosis. High-resolution MRI offers additional insights into plaque morphology including plaque burden, hemorrhage, remodeling, and contrast enhancement. These metrics and plaque traits help identify symptomatic plaques. Techniques like transcranial Doppler, CT perfusion, computational fluid dynamics, and quantitative MRA analyze blood flow restrictions due to ICAD. Intravascular ultrasound or optical coherence tomography have a very high spatial resolution and can assess the structure of the arterial wall and the plaque from the lumen of the target vascular territory. Positron emission tomography could further detect inflammation markers. This review aims to provide a comprehensive overview of the spectrum of current modalities for atherosclerotic plaque analysis and risk stratification.

High-risk plaque characteristics associated with recurrent stroke in patients with intracranial stenosis: a systematic review and meta-analysis

BACKGROUND

Risk stratification based on intracranial plaque characteristics is crucial for patients with intracranial atherosclerosis (ICAS). Nonetheless, there remains a significant deficit of validated imaging markers capable of predicting recurrent strokes. Consequently, we conducted a systematic review and meta-analysis to investigate the prognostic significance of high-risk plaque characteristics (HPCs) in relation to recurrent stroke.

METHODS

The systematic review was registered in PROSPERO (CRD420245820945). We systematically searched PubMed, Ovid Medline, and Web of Science for studies evaluating the association between HPCs and risk of stroke recurrence. Data were aggregated and pooled using a random-effects meta-analysis. Heterogenicity and publication bias were assessed, with subgroup and sensitivity analyses performed where appropriate.

RESULTS

Eighteen studies, comprising 13 prospective and 5 retrospective, involving a total of 4967 patients (3594 symptomatic, and 1373 asymptomatic), were included in the analysis. Among symptomatic patients, those with HPCs exhibited a higher incidence of stroke recurrence compared to those without HPCs (adjusted HR, 3.90 ([95% CI, 2.15-7.08]). ICAS patients with baseline plaque enhancement (adjusted HR, 5.20 [95% CI, 3.12-8.66]), calcification (adjusted HR, 2.92 [95% CI, 1.32-6.45]), high plaque steepness (adjusted HR, 110.27 [95% CI, 4.75-2559.74]), and progression in plaque burden (adjusted HR, 6.29 [95% CI, 1.62-24.45]) were identified as being at an increased risk of stroke recurrence. Subgroup analyses revealed that traditional cerebrovascular risk factors, including increasing age, hypertension, diabetes mellitus, and smoking, further elevated the risk of HPC-related stroke recurrence in ICAS patients.

CONCLUSION

The identification of HPCs confers independent prognostic value for the prediction of stroke recurrence in ICAS patients, which could be instrumental for patients risk stratification.

Evaluation of Intensive Statins and Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors on Intracranial Artery Plaque Stability: A Prospective Single-Arm Study

BACKGROUND

Intracranial atherosclerotic stenosis is a leading cause of ischemic stroke and recurrent events due to plaque instability. High-resolution magnetic resonance imaging identifies plaque enhancement as a key marker of instability. This study evaluated the efficacy of combined high-intensity statins and proprotein convertase subtilisin/kexin type 9 inhibitors in plaque stabilization.

METHODS

In this prospective, single-arm study, patients with acute stroke and intracranial atherosclerotic stroke in the M1 segment of the middle cerebral artery or basilar artery were enrolled. After 24 weeks of intensive statin and evolocumab therapy, high-resolution magnetic resonance imaging assessments of intracranial vessels were conducted at baseline and follow-up. The primary end point was the change in stenosis degree; secondary end points included changes in plaque enhancement (contrast ratio) and plaque burden.

RESULTS

Thirty-six patients (median age, 58 years) participated. After therapy, stenosis decreased from 75.9% (interquartile range, 69.5%-84.8%) to 65.3% (interquartile range, 53.8%-75.0%; P<0.001). Contrast ratio grades and contrast volume decreased significantly (P<0.001), and lumen area increased (from 1.03 mm2 [interquartile range, 0.59-1.72 mm2] to 2.08 mm2 [interquartile range, 1.00-3.10 mm2]; P<0.001). No significant changes were observed in wall area, wall area index, or remodeling index. A notable correlation between the decrease in low-density lipoprotein cholesterol/apolipoprotein B ratio and reduction in contrast volume was observed.

CONCLUSIONS

Combining proprotein convertase subtilisin/kexin type 9 inhibitors with high-intensity statins may improve plaque stability and reduce lumen stenosis in patients with intracranial atherosclerotic stenosis. Larger randomized controlled trials are needed to confirm these findings.

REGISTRATION

URL: https://www.chictr.org.cn; Unique identifier: ChiCTR2200058029.

DANTE-CAIPI Accelerated Contrast-Enhanced 3D T1: Deep Learning-Based Image Quality Improvement for Vessel Wall MRI

BACKGROUND AND PURPOSE

Accelerated and blood-suppressed postcontrast 3D intracranial vessel wall MRI (IVW) enables high-resolution rapid scanning but is associated with low SNR. We hypothesized that a deep-learning (DL) denoising algorithm applied to accelerated, blood-suppressed postcontrast IVW can yield high-quality images with reduced artifacts and higher SNR in shorter scan times.

MATERIALS AND METHODS

Sixty-four consecutive patients underwent IVW, including conventional postcontrast 3D T1-sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE) and delay alternating with nutation for tailored excitation (DANTE) blood-suppressed and CAIPIRINHIA-accelerated (CAIPI) 3D T1-weighted TSE postcontrast sequences (DANTE-CAIPI-SPACE). DANTE-CAIPI-SPACE acquisitions were then denoised by using an unrolled deep convolutional network (DANTE-CAIPI-SPACE+DL). SPACE, DANTE-CAIPI-SPACE, and DANTE-CAIPI-SPACE+DL images were compared for overall image quality, SNR, severity of artifacts, arterial and venous suppression, and lesion assessment by using 4-point or 5-point Likert scales. Quantitative evaluation of SNR and contrast-to-noise ratio (CNR) was performed.

RESULTS

DANTE-CAIPI-SPACE+DL showed significantly reduced arterial (1 [1-1.75] versus 3 [3-4], P < .001) and venous flow artifacts (1 [1-2] versus 3 [3-4], P < .001) compared with SPACE. There was no significant difference between DANTE-CAIPI-SPACE+DL and SPACE in terms of image quality, SNR, artifact ratings, and lesion assessment. For SNR ratings, DANTE-CAIPI-SPACE+DL was significantly better compared with DANTE-CAIPI-SPACE (2 [1-2], versus 3 [2-3], P < .001). No statistically significant differences were found between DANTE-CAIPI-SPACE and DANTE-CAIPI-SPACE+DL for image quality, artifact, arterial blood and venous blood flow artifacts, and lesion assessment. Quantitative vessel wall SNR and CNR median values were significantly higher for DANTE-CAIPI-SPACE+DL (SNR: 9.71, CNR: 4.24) compared with DANTE-CAIPI-SPACE (SNR: 5.50, CNR: 2.64) (P < .001 for each), but there was no significant difference between SPACE (SNR: 10.82, CNR: 5.21) and DANTE-CAIPI-SPACE+DL.

CONCLUSIONS

DL denoised postcontrast T1-weighted DANTE-CAIPI-SPACE accelerated and blood-suppressed IVW showed improved flow suppression with a shorter scan time and equivalent qualitative and quantitative SNR measures relative to conventional postcontrast IVW. It also improved SNR metrics relative to postcontrast DANTE-CAIPI-SPACE IVW. Implementing DL denoised DANTE-CAIPI-SPACE IVW has the potential to shorten protocol time while maintaining or improving the image quality of IVW.

Atherosclerotic plaque evolution predicts cerebral ischemic events in patients with intracranial atherosclerosis: a multicentre longitudinal study using high-resolution MRI

BACKGROUND

Intracranial atherosclerosis (ICAS) is the leading cause of ischemic stroke in Asians and the recurrent rate remains high despite the optimal medical treatment. This study aimed to confirm that follow-up high-resolution magnetic resonance imaging (hrMRI) provided essential values in predicting subsequent cerebral ischemic events in patients with ICAS.

METHODS

Patients with moderate to severe stenosis in the middle cerebral artery (MCA) defined by magnetic resonance (MRA) or computed tomography angiography (CTA) were recruited from three centers retrospectively. Detailed plaque composition was analyzed on baseline and follow-up hrMRI. Multivariate Cox proportional hazards regression analysis was used to identify the key risk factors for predicting subsequent ischemic events.

RESULTS

Among 152 patients, a total of 86 patients with MCA atherosclerotic stenosis underwent follow-up hrMRI exams and ipsilateral cerebral ischemic events occurred in 12 patients during a 1-year follow-up. Analyses showed the predictors of ischemic events were age (adjusted Hazard ratio (HR) = 0.942; 95% Confidence Interval (CI), [0.903, 0.983]; p = 0.006), progression of plaque burden (HR = 3.818; 95% CI [1.117, 13.051]; p = 0.033), vessel expansion (HR = 5.173; 95% CI [1.077, 24.838]; p = 0.040) and enhancement ratio progression (HR = 6.144; 95% CI [1.480, 25.511]; p = 0.012). The combined model achieved a concordance index of 0.804 (95% CI [0.658, 0.950]).

CONCLUSION

Longitudinal hrMRI evaluation improved the accuracy in identifying higher-risk patients with intracranial atherosclerosis.

KEY POINTS

Question Can longitude high-resolution magnetic resonance imaging (hrMRI) help clinicians observe intracranial plaque evolution? Findings Compared with the baseline exam, intracranial plaque evolution distinguished by follow-up hrMRI exam showed a higher accuracy in predicting subsequent ischemic events. Clinical relevance Longitudinal high-resolution magnetic resonance vessel wall imaging enables dynamic observation and evaluation of the changes in plaque characteristics among intracranial atherosclerosis patients. Atherosclerotic plaque evolution revealed by repeated exams can strengthen the risk stratification of patients with intracranial atherosclerosis.

Advancements in imaging of intracranial atherosclerotic disease: beyond the arterial lumen to the vessel wall

Intracranial atherosclerotic disease (ICAD) significantly increases the risk of ischemic stroke. It involves the accumulation of plaque within arterial walls and narrowing or blockage of blood vessel lumens. Accurate imaging is crucial for the diagnosis and management of ICAD at both acute and chronic stages. However, imaging the small, tortuous intracranial arterial walls amidst complex structures is challenging. Clinicians have employed diverse approaches to improve imaging quality, with a particular emphasis on optimizing the acquisition of images using new techniques, enhancing spatial and temporal resolution of images, and refining post-processing techniques. ICAD imaging has evolved from depicting lumen stenosis to assessing blood flow reserve and identifying plaque components. Advanced techniques such as fractional flow reserve (FFR), high-resolution vessel wall magnetic resonance (VW-MR), optical coherence tomography (OCT), and radial wall strain (RWS) now allow direct visualization of flow impairment, vulnerable plaques, and blood flow strain to plaque, aiding in the selection of high-risk stroke patients for intervention. This article reviews the progression of imaging modalities from lumen stenosis to vessel wall pathology and compares their diagnostic value for risk stratification in ICAD patients.

Plaque Evolution and Vessel Wall Remodeling of Intracranial Arteries: A Prospective, Longitudinal Vessel Wall MRI Study

BACKGROUND

Progression of intracranial atherosclerotic disease (ICAD) is associated with ischemic stroke events and can be quantified with three-dimensional (3D) intracranial vessel wall (IVW) MRI. However, longitudinal 3D IVW studies are limited and ICAD evolution remains relatively unknown.

PURPOSE

To evaluate ICAD changes longitudinally and to characterize the imaging patterns of atherosclerotic plaque evolution.

STUDY TYPE

Prospective.

POPULATION

37 patients (69 ± 12 years old, 12 females) with angiography confirmed ICAD.

FIELD STRENGTH/SEQUENCE

3.0T/3D time-of-flight gradient echo sequence and T1- and proton density-weighted fast spin echo sequences.

ASSESSMENT

Each patient underwent baseline and 1-year follow-up IVW. Then, IVW data from both time points were jointly preprocessed using a multitime point, multicontrast, and multiplanar viewing workflow (known as MOCHA). Lumen and outer wall of plaques were traced and measured, and plaques were then categorized into progression, stable, and regression groups based on changes in plaque wall thickness. Patient demographic and clinical data were collected. Culprit plaques were identified based on cerebral ischemic infarcts.

STATISTICAL TESTS

Generalized estimating equations-based linear and logistic regressions were used to assess associations between vascular risk factors, medications, luminal stenosis, IVW plaque imaging features, and longitudinal changes. A two-sided P-value<0.05 was considered statistically significant.

RESULTS

Diabetes was significantly associated with ICAD progression, resulting in 6.6% decrease in lumen area and 6.7% increase in wall thickness at 1-year follow-up. After accounting for arterial segments, baseline contrast enhancement predicted plaque progression (odds ratio = 3.61). Culprit plaques experienced an average luminal expansion of 10.9% after 1 year. 74% of the plaques remained stable during follow-up. The regression group (18 plaques) showed significant increase in minimum lumen area (from 7.4 to 8.3 mm2), while the progression group (13 plaques) showed significant decrease in minimum lumen area (from 5.4 to 4.3 mm2).

DATA CONCLUSION

Longitudinal 3D IVW showed ICAD remodeling on the lumen side. Culprit plaques demonstrated longitudinal luminal expansion compared with their non-culprit counterparts. Baseline plaque contrast enhancement and diabetes mellitus were found to be significantly associated with ICAD changes.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 3.

Carotid atherosclerotic plaque predicts progression of intracranial artery atherosclerosis: A MR imaging-based community cohort study

PURPOSE

Intracranial artery atherosclerosis (ICAS) progression is associated with stroke. However, the association of carotid plaque with ICAS progression among stroke-free participants is still unclear. This study aimed to evaluate the association between carotid plaque and ICAS progression in stroke-free participants.

METHOD

Stroke-free participants were recruited from a community-based cohort study. All participants underwent questionnaire interviews, blood tests, and high-resolution vessel wall magnetic resonance (MR) imaging at baseline and follow-up for around three years. The atherosclerotic plaque was defined as eccentric wall thickening on MR imaging. The presence, location, total number, and burden (maximum wall thickness, length, and stenosis) of carotid and intracranial plaque were evaluated. ICAS progression was defined as the number increased or plaque burden (maximum wall thickness, length, or stenosis increase) increased by ≥ 20 %. The association between carotid plaque and ICAS progression was evaluated using multivariable logistic regression.

RESULTS

Of the 312 participants (mean age at baseline: 59.85 ± 13.04 years; 136 males) who completed baseline and follow-up studies with a mean time interval of 3.15 ± 0.59 years, 85 (27.24 %) had progression of ICAS during follow-up. At least one carotid plaque was detected at baseline in 167 (53.53 %) participants. In the multivariable logistic analysis, carotid plaque was a significant predictor for the progression of ICAS (odds ratio, 2.04; 95 % confidence interval, 1.06-3.92; P = 0.032).

CONCLUSIONS

Carotid plaque is associated with intracranial artery atherosclerosis progression in stroke-free population. Our findings suggest that carotid plaque may be an effective predictor for intracranial artery atherosclerosis progression.

Can combined high-resolution vessel wall imaging and multiple post-labeling delay 3D pseudo-continuous arterial spin labeling differentiate moyamoya disease from atherosclerotic moyamoya syndrome?

PURPOSE

To investigate whether moyamoya disease (MMD) and atherosclerotic moyamoya syndrome (AS-MMS) differ in vascular morphology and perfusion characteristics using T1w-CUBE imaging and multiple post-labeling delay 3D pseudo-continuous arterial spin labeling imaging (MP 3D-PcASL), and to explore the potential of the combined techniques for accurate diagnosis of both diseases.

METHOD

This prospective study enrolled 51 patients with moyamoya vasculopathy, including 26 with MMD and 25 with AS-MMS. All patients underwent digital subtraction angiography (DSA)/magnetic resonance angiography (MRA), T1w-CUBE imaging, and MP 3D-PCASL examinations. Morphological parameters, including the outer diameter, maximum wall thickness, luminal stenosis morphology, degree of wall enhancement, number of collateral vessels, and perfusion parameters, such as cerebral blood flow (CBF) and arterial transit time (ATT), were measured. After univariate analysis between the two groups, logistic regression models based on the derived parameters of T1w-CUBE imaging, MP 3D-PCASL, and combined imaging were implemented, and receiver operating characteristic (ROC) curves were generated to compare the discriminatory power of the different imaging methods for the diagnosis of MMD.

RESULTS

With T1w-CUBE imaging, MMD showed a smaller outer diameter (2.76 ± 0.39 vs. 3.07 ± 0.49 mm) and maximum wall thickness (1.27 ± 0.19 vs. 1.49 ± 0.24 mm) than AS-MMS (both P < 0.05). Using MP 3D-pcASL, the resultant CBF (36.64 ± 14.28 vs. 28.77 ± 8.63 mL/100 g/min) was higher in MMD relative to AS-MMS, while an opposite pattern was shown for ATT (1.61 ± 0.09 vs. 1.72 ± 0.13 s; both P < 0.05). Robust diagnostic efficacies for disease differentiation, confirmed by high areas under the ROC curve (AUCs) (>0.808), were separately shown with T1w-CUBE and MP 3D-pcASL derived parameters. However, the combined multivariate logistic regression model showed optimaldiagnostic efficacy(AUC: 0.938; P < 0.05).

CONCLUSIONS

Combined T1w-CUBE imaging and MP 3D-PCASL provides distinctive morphological and functional features to evaluate vessel walls and cerebral perfusion, and might help distinguish MMD from AS-MMS.

Association of culprit plaque enhancement ratio, hypoperfusion and HbA1c with recurrent ischemic stroke in patients with atherosclerotic stenosis of the middle cerebral artery

PURPOSE

To investigate the differences in intracranial culprit plaque characteristics of the middle cerebral artery (MCA), collateral circulation and hypoperfusion in patients with and without recurrent ischemic stroke and to identify the association with the recurrent ischemic cerebrovascular events.

METHOD

Eighty-six patients with acute/subacute ischemic stroke caused by atherosclerotic plaques of the MCA were retrospectively enrolled and grouped into patients with recurrence (n = 36) and without recurrence (n = 50). All patients underwent high-resolution vessel wall imaging and dynamic susceptibility contrast-enhanced perfusion weighted imaging. The differences in culprit plaque characteristics, collateral circulation and hypoperfusion in the territory of the stenotic MCA were assessed between the two groups. The relationship between plaque characteristics and hypoperfusion was evaluated. The independent factors of recurrent ischemic stroke were identified by logistic regression analyses.

RESULTS

Higher HbA1c, culprit plaque enhancement grade, culprit plaque enhancement ratio, and lower time to peak map based on the Alberta Stroke Program Early CT score (TTP-ASPECTS) were observed in the recurrence group(all p < 0.050). Both plaque enhancement grade and enhancement ratio were significantly associated with TTP-ASPECTS (p = 0.030 and 0.039, respectively). HbA1c, culprit plaque enhancement ratio and TTP-ASPECTS were independent factors of the recurrence of ischemic stroke (all p < 0.050). The area under the curve of the combination including the above factors (AUC = 0.819) was significantly higher than that of any variable alone after adjustment (all p < 0.050).

CONCLUSIONS

Culprit plaque enhancement ratio, TTP-ASPECTS and HbA1c were independent factors of recurrent ischemic stroke. Their combination improved the accuracy in identifying the risk of recurrent ischemic stroke.

Co-existing intracranial and extracranial carotid atherosclerosis predicts large-artery atherosclerosis stroke recurrence: a single-center prospective study utilizing combined head-and-neck vessel wall imaging

OBJECTIVES

Intracranial and extracranial plaque features on high-resolution vessel wall imaging (HR-VWI) are associated with large-artery atherosclerosis (LAA) stroke recurrence. However, most studies have focused on a single vascular bed, and the prognostic value of combined intracranial and extracranial plaque features has yet to be studied. This study aimed to investigate the roles of plaque features, plaque number, and co-existing atherosclerosis in predicting stroke recurrence, utilizing combined head-and-neck HR-VWI.

METHODS

From September 2016 to March 2020, participants with acute LAA ischemic strokes were prospectively enrolled and underwent combined head-and-neck HR-VWI. The participants were followed for stroke recurrence for at least 12 months or until a subsequent event occurred. The imaging features at baseline, including conventional and histogram plaque features, plaque number, and co-existing atherosclerosis, were evaluated. Univariable Cox regression analysis and the least absolute shrinkage and selection operator (lasso) method were used for variable screening. Multivariable Cox regression analyses were used to determine the independent risk factors of stroke recurrence.

RESULTS

A total of 97 participants (59 ± 12 years, 63 men) were followed for a median of 30.9 months, and 21 participants experienced recurrent strokes. Multivariable Cox analysis identified co-existing intracranial high signal on T1-weighted fat-suppressed images (HST1) and extracranial carotid atherosclerosis (HR, 6.12; 95% CI, 2.52-14.82; p = 0.001) as an independent imaging predictor of stroke recurrence.

CONCLUSION

Co-existing intracranial HST1 and extracranial carotid atherosclerosis independently predicted LAA stroke recurrence. Combined head-and-neck HR-VWI is a promising technique for atherosclerosis imaging.

CLINICAL RELEVANCE STATEMENT

This prospective study using combined head-and-neck HR-VWI highlighted the necessity of both intracranial culprit plaque evaluation and multi-vascular bed assessment, adding value to the prediction of stroke recurrence.

KEY POINTS

• This study highlighted the necessity of both intracranial culprit plaque evaluation and multi-vascular bed assessment, adding value to the prediction of stroke recurrence. • This prospective study using combined head-and-neck HR-VWI found co-existing intracranial HST1 and extracranial carotid atherosclerosis to be independent predictors of stroke recurrence.

Qualitative and quantitative plaque enhancement on high-resolution vessel wall imaging predicts symptomatic intracranial atherosclerotic stenosis

BACKGROUND AND PURPOSE

Intracranial atherosclerotic stenosis (ICAS) is a major cause of ischemic stroke (IS), and high-resolution vessel wall imaging (HR-VWI) can be used to assess the plaque characteristics of ICAS. This study aimed to qualitatively and quantitatively assess plaque enhancement of ICAS and to investigate the relationship between plaque enhancement, plaque morphological features, and IS.

METHODS

Data from adult patients with ICAS from April 2018 to July 2022 were retrospectively collected, and all patients underwent HR-VWI examination. Plaque enhancement was qualitatively and quantitatively assessed, and the plaque-to-pituitary stalk contrast ratio (CR) indicated the degree of plaque enhancement. Plaque characteristics, such as plaque burden and area, were quantitatively measured using HR-VWI. Furthermore, receiver-operating characteristic (ROC) analysis was performed to assess the ability of CR to discriminate plaque enhancement. The patients were divided into a symptomatic ICAS group and an asymptomatic ICAS group according to the clinical and imaging characteristics. Univariate and multivariate analyses were performed to investigate which factors were significantly associated with plaque enhancement and symptomatic ICAS. The plaque burden and CR were compared using linear regression.

RESULTS

A total of 91 patients with ICAS were enrolled in this study. ICAS plaque burden was significantly associated with plaque enhancement (p = .037), and plaque burden was linearly positively correlated with CR (R = 0.357, p = .001). ROC analysis showed that the cutoff value of CR for plaque enhancement was 0.56 (specificity of 81.8%). Both plaque enhancement and plaque burden were significantly associated with symptomatic ICAS, and only plaque enhancement was an independent risk factor after multivariate analysis.

CONCLUSION

Plaque burden was an independent risk factor for plaque enhancement and showed a linear positive correlation with CR. The cutoff value of CR for plaque enhancement was 0.56, and CR ≥ 0.56 was significantly associated with symptomatic ICAS, which was independently associated with plaque enhancement.

Exploration of the etiology of single small subcortical infarctions using high-resolution vessel wall MRI

Objective

We aimed to explore imaging indicators for diagnosing the etiology of single small subcortical infarctions (SSI) using high-resolution vessel wall imaging (HR-VWI).

Methods

Patients with acute isolated subcortical cerebral infarction were prospectively enrolled and classified as having large artery atherosclerosis (LAA), stroke of undetermined etiology (SUD), or small artery disease (SAD). The infarct information, the cerebral small vessel disease (CSVD) score, morphological characteristics of the lenticulostriate arteries (LSAs), and plaque characteristics were compared between the three groups.

Results

Seventy seven patients were enrolled (30 LAA, 28 SUD, and 19 SAD). The total CSVD score of the LAA (P = 0.001) and SUD groups (P = 0.017) was significantly lower than that of the SAD group. The number and total length of LSA branches in the LAA and SUD groups were shorter than in the SAD group. Moreover, the total length laterality index (LI) of the LSAs in the LAA and SUD groups was greater than in the SAD group. The total CSVD score and LI of total length were independent predictors for the SUD and LAA groups. The remodeling index of the SUD group was significantly higher than that of the LAA group (P = 0.002); positive remodeling was dominant in the SUD group (60.7%), whereas remodeling in the LAA group was primarily non-positive (83.3%).

Conclusions

SSI with and without plaques on the carrier artery may have different modes of pathogenesis. Patients with plaques may also have a coexisting mechanism of atherosclerosis.

Incremental value of enhanced plaque length for identifying intracranial atherosclerotic culprit plaques: a high-resolution magnetic resonance imaging study

OBJECTIVES

Besides plaque enhancement grade, the incremental value of enhancement-related high-resolution MRI features in defining culprit plaques needs further evaluation. This study was focused on assessing whether plaque enhancement features contribute to culprit plaque identification and further risk stratification.

METHODS

We retrospectively studied patients who experienced an acute ischaemic stroke and transient ischaemic attack due to intracranial atherosclerosis from 2016 to 2022. The enhancement features included enhancement grade, enhanced length, and enhancement quadrant. Associations between plaque enhancement features and culprit plaques, as well as diagnostic value, were investigated using logistic regression and receiver operating characteristic analyses.

RESULTS

Overall, 287 plaques were identified, of which 231 (80.5%) and 56 (19.5%) were classified as culprit and non-culprit plaques, respectively. Comparison of the pre- and post-enhancement images revealed enhanced length longer than the plaque length in 46.32% of the culprit plaques. Multivariate logistic regression showed that enhanced length longer than plaque length (OR 6.77; 95% CI 2.47-18.51) and grade II enhancement (OR 7.00; 95% CI 1.69-28.93) were independently associated with culprit plaques. The area under the curve value for the combination of stenosis and plaque enhancement grade for the diagnosis of culprit plaques was 0.787, which increased significantly to 0.825 on the addition of enhanced length longer than the plaque length (p = 0.026 for DeLong's test).

CONCLUSIONS

Enhanced length longer than the plaque length and grade II enhancement were independently associated with culprit plaques. The combination of the enhanced plaque features resulted in better culprit plaque identification.

Vessel Wall Imaging in Cryptogenic Stroke

Cryptogenic strokes are symptomatic cerebral ischemic infarcts without a clear etiology identified following standard diagnostic evaluation and currently account for 10% to 40% of stroke cases. Continued research is needed to identify and bridge gaps in knowledge of this stroke grouping. Vessel wall imaging has increasingly shown its utility in the diagnosis and characterization of various vasculopathies. Initial promising evidence suggests rational use of vessel wall imaging in stroke workup may unravel pathologies that otherwise would have been occult and further improve our understanding of underlying disease processes that can translate into improved patient outcomes and secondary stroke prevention.

Distinguishing Intracranial Diabetes-Related Atherosclerotic Plaques: A High-Resolution Magnetic Resonance Imaging-Based Radiomics Study

INTRODUCTION

Diabetes markedly affects the formation and development of intracranial atherosclerosis. The study was aimed at evaluating whether radiomics features can help distinguish plaques primarily associated with diabetes.

MATERIALS AND METHODS

We retrospectively analyzed patients who were admitted to our center because of acute ischemic stroke due to intracranial atherosclerosis between 2016 and 2022. Clinical data, blood biomarkers, conventional plaque features, and plaque radiomics features were collected for all patients. Odds ratios (ORs) with 95% confidence intervals (CIs) were determined from logistic regression models. The receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) were used to describe diagnostic performance. The DeLong test was used to compare differences between models.

RESULTS

Overall, 157 patients (115 men; mean age, 58.7 ± 10.7 years) were enrolled. Multivariate logistic regression analysis showed that plaque length (OR: 1.17; 95% CI: 1.07-1.28) and area (OR: 1.13; 95% CI: 1.02-1.24) were independently associated with diabetes. On combining plaque length and area as a conventional model, the AUCs of the training and validation cohorts for identifying diabetes patients were 0.789 and 0.720, respectively. On combining radiomics features on T1WI and contrast-enhanced T1WI sequences, a better diagnostic value was obtained in the training and validation cohorts (AUC: 0.889 and 0.861). The DeLong test showed the model combining radiomics and conventional plaque features performed better than the conventional model in both cohorts (p < 0.05).

CONCLUSIONS

The use of radiomics features of intracranial plaques on high-resolution magnetic resonance imaging can effectively distinguish culprit plaques with diabetes as the primary pathological cause, which will provide new avenues of research into plaque formation and precise treatment.

Intracranial atherosclerotic plaque enhancement and long-term risk of future strokes: A prospective, longitudinal study

BACKGROUND AND PURPOSE

The prognostic significance of postcontrast enhancement of intracranial atheromatous plaque is uncertain. Prospective, long-term follow-up studies in Caucasians, using a multicenter design, are lacking. We aimed to evaluate whether this radiological sign predicts long-term new stroke in symptomatic and asymptomatic intracranial atherosclerotic disease (ICAD) patients.

METHODS

This was a prospective, observational, longitudinal, multicenter study. We included a symptomatic and an asymptomatic cohort of ICAD patients that underwent 3T MRI including high-resolution sequences focused on the atheromatous plaque. We evaluated grade of stenosis, plaque characteristics, and gadolinium enhancement ratio (postcontrast plaque signal/postcontrast corpus callosum signal). The occurrence of new events was evaluated at 3, 6, 9, and 12 months and annually thereafter. The association between plaque characteristics and new stroke was studied using Cox multiple regression survival analysis and Kaplan-Meier curves.

RESULTS

Forty-eight symptomatic and 13 asymptomatic patients were included. During 56.3 ± 16.9 months, 11 patients (18%) suffered a new event (seven ischemic, two hemorrhagic, and two transient ischemic attacks). A receiver operating characteristic curve identified an enhancement ratio of >1.77 to predict a new event. In a multivariable Cox regression, postcontrast enhancement ratio >1.77 (hazard ratio [HR]= 3.632; 95% confidence interval [CI], 1.082-12.101) and cerebral microbleeds (HR = 5.244; 95% CI, 1.476-18.629) were independent predictors of future strokes. Patients with a plaque enhancement ratio >1.77 had a lower survival free of events (p < .05).

CONCLUSIONS

High intracranial postcontrast enhancement is a long-term predictor of new stroke in ICAD patients. Further studies are needed to elucidate whether postcontrast enhancement reflects inflammatory activity of intracranial atheromatous plaque.

Correlation of sLOX-1 Levels and MR Characteristics of Culprit Plaques in Intracranial Arteries with Stroke Recurrence

(1) Background: Symptomatic intracranial artery atherosclerosis (sICAS) is an important cause of acute ischaemic stroke (AIS) and is associated with a high risk of stroke recurrence. High-resolution magnetic resonance vessel wall imaging (HR-MR-VWI) is an effective method for evaluating atherosclerotic plaque characteristics. Soluble lectin-like oxidised low-density lipoprotein receptor-1 (sLOX-1) is closely associated with plaque formation and rupture. We aim to explore the correlation between sLOX-1 levels and culprit plaque characteristics, based on HR-MR-VWI, with stroke recurrence in patients with sICAS. (2) Methods: A total of 199 patients with sICAS underwent HR-MR-VWI between June 2020 and June 2021 in our hospital. The culprit vessel and plaque characteristics were assessed according to HR-MR-VWI, and sLOX-1 levels were measured by ELISA (enzyme linked immunosorbent assay). Outpatient follow-up was performed 3, 6, 9, and 12 months after discharge. (3) Results: sLOX-1 levels were significantly higher in the recurrence group than in the non-recurrence group (p < 0.001). The culprit plaque thickness, degree of stenosis and plaque burden were higher in the recurrence group than in the non-recurrence group (p = 0.003, p = 0.014 and p = 0.010, respectively). The incidence of hyperintensity on T1WI, positive remodelling and significant enhancement (p < 0.001, p = 0.003 and p = 0.027, respectively) was higher in the recurrence group than in the non-recurrence group. Kaplan-Meier curves showed that patients with sLOX-1 levels > 912.19 pg/mL and hyperintensity on T1WI in the culprit plaque had a higher risk of stroke recurrence (both p < 0.001). Multivariate Cox regression analysis showed that sLOX-1 > 912.19 pg/mL (HR = 2.583, 95%CI 1.142, 5.846, p = 0.023) and hyperintensity on T1WI in the culprit plaque (HR = 2.632, 95% CI 1.197, 5.790, p = 0.016) were independent risk factors for stroke recurrence. sLOX-1 levels were significantly associated with the culprit plaque thickness (r = 0.162, p = 0.022), degree of stenosis (r = 0.217, p = 0.002), plaque burden (r = 0.183, p = 0.010), hyperintensity on T1WI (F = 14.501, p < 0.001), positive remodelling (F = 9.602, p < 0.001), and significant enhancement (F = 7.684, p < 0.001) (4) Conclusions: sLOX-1 levels were associated with vulnerability of the culprit plaque and can be used as a supplement to HR-MR-VWI to predict stroke recurrence.

Effect of Mid-Basilar Artery Angle and Plaque Characteristics on Pontine Infarction in Patients with Basilar Artery Plaque

AIMS

The basilar artery (BA) geometry and plaque characteristics may play an important role in the development of atherosclerosis. This study was performed to explore the relationship between the mid-BA angle and plaque characteristics and its effect on pontine infarction using high-resolution magnetic resonance imaging and three-dimensional time-of-flight magnetic resonance angiography.

METHODS

In total, 77 patients with BA plaques were included in this study. According to the presence of acute pontine infarction on diffusion-weighted imaging, the patients were divided into a pontine infarction group and pontine non-infarction group. The mid-BA angle, plaque burden, stenosis ratio, positive remodeling, and intraplaque hemorrhage were evaluated to investigate their effects on stroke.

RESULTS

The pontine infarction group had a greater plaque burden, stenosis ratio, positive remodeling, and mid-BA angle than the pontine non-infarction group. The correlation between the plaque burden and mid-BA angle was the highest (r=0.441, P＜0.001). Multivariate logistic regression analysis showed that the plaque burden (odds ratio, 1.164; 95% confidence interval, 1.093-1.241; P＜0.001) was an independent risk factor for pontine infarction.

CONCLUSION

The mid-BA angle may increase the incidence of pontine infarction by increasing the plaque burden.

Intracranial plaque characteristics on high-resolution MRI and high-sensitivity C-reactive protein levels: association and clinical relevance in acute cerebral infarction

AIM

To investigate the association between intracranial plaque characteristics and high-sensitivity C-reactive protein (hs-CRP) levels, and their combined effects on the occurrence of acute cerebral infarction (ACI).

MATERIALS AND METHODS

One hundred and forty-three patients with recent ischaemic events in the territory of middle cerebral artery or basilar artery were enrolled and divided into the ACI group (n=93) and non-ACI group (n=50) according to clinical data and diffusion-weighting imaging (DWI) results. All recruited patients underwent high-resolution magnetic resonance imaging (MRI) to assess intracranial plaque characteristics, including plaque enhancement, standardised wall index, stenosis ratio, T1 hyperintense component, remodelling pattern, plaque area, plaque burden, and maximum wall thickness. hs-CRP levels were further grouped into the low group (<1 mg/l), the intermediate group (1-3 mg/l), and the high group (≥3 mg/l). Multivariate logistic regression and receiver operating characteristic curve were constructed to evaluate the association between intracranial plaque characteristics and hs-CRP levels, as well as their synergistic effects on determining the occurrence of ACI.

RESULTS

High hs-CRP levels were associated with strong plaque enhancement (p<0.001, odds ratio [OR] = 7.497). Strong plaque enhancement (p=0.002, OR=2.109) and high hs-CRP levels (p=0.009, OR=3.893) were independently associated with the occurrence of ACI after adjustments for sex, age, and other traditional atherosclerotic risk factors. The combination of hs-CRP levels and strong plaque enhancement provided incremental information to determine ACI with an AUC of 0.823, which was significantly higher than that of strong plaque enhancement (0.711) and hs-CRP levels (0.686), respectively.

CONCLUSION

High hs-CRP levels were associated with strong plaque enhancement. The synergistic effects of hs-CRP levels and strong plaque enhancement provided incremental effects on the occurrence of ACI.

Predictors of improvement for patients with CNS vasculitis stenoses: A high-resolution vessel wall MRI follow-up study

PURPOSE

To investigate the predictors of the improvement for patients with isolated intracranial vasculitis stenoses using high-resolution vessel wall magnetic resonance imaging (HR VW-MRI).

METHODS

We retrospectively reviewed data from consecutive patients with confirmed intracranial vasculitis under the same conventional conservative treatment based on a prospectively established HR VW-MRI database between December 2016 and December 2020. According to the changes between the degree of stenosis at baseline compared to follow-up MR angiography, the patients were divided into an improvement group and a non-improvement group. A multivariate analysis was performed to identify the predictive factors associated with the improvement of stenoses secondary to intracranial vasculitis.

RESULTS

Overall, 41 patients (mean age 32.0 ± 10.1 years, 16 females) with isolated intracranial vasculitis stenoses were included (41.5 % [17/41] in the improvement group, and 58.5 % [24/41] were in the non-improvement group). The degree of wall enhancement on follow-up imaging was significantly reduced compared with that on the baseline imaging in the improvement group (P = 0.004). The multivariate analysis showed that the degree of enhancement (OR, 0.219, 95 % CI, 0.054 to 0.881; P = 0.033) at baseline was an independent predictive factor associated with the improvement in the intracranial vasculitis stenoses.

CONCLUSIONS

In patients with isolated intracranial vasculitis stenoses, the less enhancement the vessel wall was, the more likely the degree of stenosis would be reduced by conventional conservative therapy.

Wall characteristics of atherosclerotic middle cerebral arteries in patients with single or multiple infarcts: A high-resolution MRI Study

Background and purpose

Understanding the stroke mechanism of middle cerebral artery (MCA) atherosclerosis may inform secondary prevention. The aim of this study was to explore the relationship between vascular wall characteristics and infarction patterns using high-resolution magnetic resonance imaging (HRMRI) and diffusion-weighted imaging (DWI).

Methods

From November 2018 to March 2021, patients with acute ischemic stroke due to MCA atherosclerotic disease were retrospectively analyzed. The wall characteristics of atherosclerotic MCA, including conventional characteristics and histogram-defined characteristics, were evaluated using HRMRI. Patients were divided into single-infarction and multiple-infarction groups based on DWI, and wall characteristics were compared between the two groups.

Results

Of 92 patients with MCA plaques, 59 patients (64.1%) had multiple infarcts, and 33 (35.9%) had single infarcts. The histogram-defined characteristics showed no differences between the single-infarction and multiple-infarction groups (P&gt;0.05). Plaque burden, degree of stenosis, and prevalence of intraplaque hemorrhage (IPH) were significantly greater in the multiple-infarction group than in the single-infarction group (plaque burden: P = 0.001; degree of stenosis: P = 0.010; IPH: P = 0.019). Multivariate analysis showed that plaque burden (odds ratio: 1.136; 95% confidence interval: 1.054–1.224, P = 0.001) and IPH (odds ratio: 5.248; 95% confidence interval: 1.573–17.512, P = 0.007) were independent predictors for multiple infarction.

Conclusion

IPH and plaque burden are independently associated with multiple infarcts. HRMRI may provide new insight into the mechanisms underlying the different MCA infarction patterns.

Follow-up assessment of atherosclerotic plaques in acute ischemic stroke patients using high-resolution vessel wall MR imaging

PURPOSE

Data on evolution of intracranial plaques in acute ischemic stroke patients after receiving medical therapy is still limited. We aimed to investigate the plaque features associated with culprit lesions and to explore the plaque longitudinal changes during treatment using high-resolution vessel wall MR imaging (VW-MRI).

METHODS

Twenty-three patients (16 men; mean age, 51.4 years ± 11.1) with acute ischemic stroke underwent 3-T VW-MRI for intracranial atherosclerosis and were taken follow-up assessments. Each identified plaque was retrospectively classified as culprit, probably culprit, or nonculprit. Plaque features were analyzed at both baseline and follow-up and were compared using paired t-test, paired Wilcoxon test, or McNemar's test.

RESULTS

A total of 87 intracranial plaques were identified (23 [26.4%] culprit, 10 [11.5%] probably culprit, and 54 [62.1%] nonculprit plaques). The median time interval between initial and follow-up MRI scans was 8.0 months. In the multiple ordinal logistic regression analysis, plaque contrast ratio (CR) (OR, 1.037; 95% CI, 1.013-1.062; P = 0.002) and surface irregularity (OR, 4.768; 95% CI, 1.064-21.349; P = 0.041) were independently associated with culprit plaques. During follow-up, plaque length, maximum thickness, normalized wall index (NWI), stenosis degree, and CR significantly decreased (all P-values < 0.05) in the culprit plaque group. The plaque NWI and CR dropped in the probably culprit plaques (P = 0.041, 0.026, respectively). In the nonculprit plaque group, only plaque NWI and stenosis degree showed significant decrement (P = 0.017, 0.037, respectively).

CONCLUSION

Follow-up VW-MRI may contribute to plaque risk stratification and may provide valuable insights into the evolution of different plaques in vivo.

Changes of Atherosclerotic Plaque in Cerebral Artery Stenosis According to High-Resolution MR Imaging

Atherosclerosis can affect multiple arteries, and result in stroke and heart disease. Clinical and conventional imaging is insufficient to predict the progression of atherosclerosis. This study investigates risk factors that rely on high-resolution magnetic resonance imaging (HR-MRI). Patients with cerebral artery stenosis who had undergone HR-MRI at least twice were included. The demographics, risk factors, and proportion of patients with cerebral artery stenosis were investigated. The association between atherosclerotic plaque characteristics and the progression or regression of artery stenosis was also analyzed. A total of 42 patients were analyzed, with a median follow-up of 16.88 ± 12.53 months. The mean age of all subjects was 63.1 ± 9.15 years, and 83.3% of them were male. The incidences of stenosis of the basilar, proximal internal carotid, and middle cerebral arteries were 21.4%, 61.9%, and 16.7%, respectively. Intraplaque hemorrhage (IPH) was detected in 20 (47.6%) patients. Multivariate analysis showed that age (odds ratio (OR), 0.87; p = 0.014), smoking (OR, 0.11; p = 0.033), and IPH regression (OR, 10.13; p = 0.027) were associated with stenosis regression. The progression of IPH (OR, 115.80; p = 0.007) was associated with stenosis progression. Results suggest that IPH on HR-MRI is associated with changes in cerebral atherosclerotic stenosis.

Survey of the American Society of Neuroradiology Membership on the Use and Value of Intracranial Vessel Wall MRI

BACKGROUND AND PURPOSE

Intracranial vessel wall MR imaging is an emerging technique for intracranial vasculopathy assessment. Our aim was to investigate intracranial vessel wall MR imaging use by the American Society of Neuroradiology (ASNR) members at their home institutions, including indications and barriers to implementation.

MATERIALS AND METHODS

The ASNR Vessel Wall Imaging Study Group survey on vessel wall MR imaging use, frequency, applications, MR imaging systems and field strength used, protocol development approaches, vendor engagement, reasons for not using vessel wall MR imaging, ordering-provider interest, and impact on clinical care, was distributed to the ASNR membership between April 2 and August 30, 2019.

RESULTS

There were 532 responses; 79 were excluded due to nonresponse and 42 due to redundant institutional responses, leaving 411 responses. Fifty-two percent indicated that their institution performs vessel wall MR imaging, with 71.5% performed at least 1-2 times/month, most frequently on 3T MR imaging, and 87.7% using 3D sequences. Protocols most commonly included were T1-weighted pre- and postcontrast and TOF-MRA; 60.6% had limited contributions from vendors or were still in protocol development. Vasculopathy differentiation (94.4%), cryptogenic stroke (41.3%), aneurysm (38.0%), and atherosclerosis (37.6%) evaluation were the most common indications. For those not performing vessel wall MR imaging, interpretation (53.1%) or technical (46.4%) expertise, knowledge of applications (50.5%), or limitations of clinician (56.7%) or radiologist (49.0%) interest were the most common reasons. If technical/expertise obstacles were overcome, 56.4% of those not performing vessel wall MR imaging indicated that they would perform it. Ordering providers most frequently inquiring about vessel wall MR imaging were from stroke neurology (56.5%) and neurosurgery (25.1%), while 34.3% indicated that no providers had inquired.

CONCLUSIONS

More than 50% of neuroradiology groups use vessel wall MR imaging for intracranial vasculopathy characterization and differentiation, emphasizing the need for additional technical and educational support, especially as clinical vessel wall MR imaging implementation continues to grow.

Case Report: Advantages of High-Resolution MRI in Evaluating the Efficacy of Drug Therapy for Intracranial Atherosclerotic Plaques

Intracranial atherosclerotic stenosis is one of the main causes of ischemic stroke and transient ischemic attack. High-resolution magnetic resonance imaging allows us to directly observe the intracranial artery wall, accurately assess the condition of the vascular wall, and quantitatively analyze the vascular wall and intracranial atherosclerotic plaque load. We report a case of acute cerebral infarction with left middle cerebral artery stenosis. During the first 3 weeks, the patient was treated with aspirin 100 mg and clopidogrel 75 mg daily. Afterwards, the patient continued to be given aspirin, and cilostazol 100 mg twice daily was given instead of clopidogrel. After 24 months of follow-up, we observed a significant reversal of intracranial atherosclerotic plaque using high-resolution MRI (HR-MRI) and discussed the advantages of HR-MRI in evaluating drug therapy for intracranial atherosclerotic plaque.

Radiomics Nomogram for Predicting Stroke Recurrence in Symptomatic Intracranial Atherosclerotic Stenosis

Objective

To develop and validate a radiomics nomogram for predicting stroke recurrence in symptomatic intracranial atherosclerotic stenosis (SICAS).

Methods

The data of 156 patients with SICAS were obtained from the hospital database. Those with and without stroke recurrence were identified. The 156 patients were separated into a training cohort (n = 110) and a validation cohort (n = 46). Baseline clinical data were collected from our medical records, and plaque radiological features were extracted from vascular wall high-resolution imaging (VW-HRMRI). The imaging sequences included 3D-T1WI-VISTA, T2WI, and 3D-T1WI-VISTA-enhanced imaging. Least absolute shrinkage and selection operator (LASSO) analysis were used to select the radiomics features associated with stroke recurrence. Then, multiple logistic regression analysis of clinical risk factors, radiological features, and radiomics signatures were performed, and a predictive nomogram was constructed to predict the probability of stroke recurrence in SICAS. The performance of the nomogram was evaluated.

Results

Diabetes mellitus, plaque burden, and enhancement ratio were independent risk factors for stroke recurrence [odds ratio (OR) = 1.24, 95% confidence interval (CI): 1.04–3.79, p = 0.018; OR = 1.76, per 10% increase, 95% CI, 1.28–2.41, p < 0.001; and OR = 1.94, 95% CI: 1.27–3.09, p < 0.001]. Five features of 3D-T1WI-VISTA, six features of T2WI, and nine features of 3D-T1WI-VISTA-enhanced images were associated with stroke recurrence. The radiomics signature in 3D-T1WI-VISTA-enhanced images was superior to the radiomics signature of the other two sequences for predicting stroke recurrence in both the training cohort [area under the curve (AUC), 0.790, 95% CI: 0.669–0.894] and the validation cohort (AUC, 0.779, 95% CI: 0.620–0.853). The combination of clinical risk factors, radiological features, and radiomics signature had the best predictive value (AUC, 0.899, 95% CI: 0.844–0.936 in the training cohort; AUC, 0.803, 95% CI: 0.761–0.897 in the validation cohort). The C-index of the nomogram was 0.880 (95% CI: 0.805–0.934) and 0.817 (95% CI: 0.795–0.948), respectively, in the training and validation cohorts. The decision curve analysis further confirmed that the radiomics nomogram had good clinical applicability with a net benefit of 0.458.

Conclusion

The radiomics features were helpful to predict stroke recurrence in patients with SICAS. The nomogram constructed by combining clinical high-risk factors, plaque radiological features, and radiomics features is a reliable tool for the individualized risk assessment of predicting the recurrence of SICAS stroke.

A Predictive Model for the Risk of Posterior Circulation Stroke in Patients with Intracranial Atherosclerosis Based on High Resolution MRI

Intracranial vertebrobasilar atherosclerosis is the main cause of posterior circulation ischemic stroke. We aimed to construct a predictive model for the risk of posterior circulation ischemic stroke in patients with posterior circulation atherosclerosis based on high-resolution MRI (HR-MRI). A total of 208 consecutive patients with posterior circulation atherosclerosis confirmed by HR-MRI, from January 2020 to July 2021, were retrospectively assessed. They were assigned to the posterior circulation stroke (49 patients) and non-posterior circulation stroke group (159 patients) based on clinical presentation and diffusion-weighted imaging (DWI). Demographic data, risk factors of atherosclerosis, laboratory findings, and imaging characteristics were extracted from electronic health records. Plaque features were investigated by HR-MRI. Fifty-three clinical or imaging features were used to derive the model. Multivariable logistic regression analysis was employed to construct the prediction model. The nomogram was evaluated for calibration, differentiation, and clinical usefulness. Plaque enhancement, plaque irregular surface morphology, artery location of plaque, and dorsal quadrant of plaque location were significant predictors for posterior circulation stroke in patients with intracranial atherosclerosis. Subsequently, these variables were selected to establish a nomogram. The model showed good distinction (C-index 0.830, 95% CI 0.766-0.895). The calibration curve also showed excellent consistency between the prediction of the nomogram and the observed curve. Decision curve analysis further demonstrated that the nomogram conferred significantly high clinical net benefit. The nomogram calculated from plaque characteristics in HR-MRI may accurately predict the posterior circulation stroke occurrence and be of great help for stratification of stroke decision making.

Large Culprit Plaque and More Intracranial Plaques Are Associated with Recurrent Stroke: A Case-Control Study Using Vessel Wall Imaging

BACKGROUND AND PURPOSE

Intracranial atherosclerotic plaque features are potential factors associated with recurrent stroke, but previous studies only focused on a single lesion, and few studies investigated them with perfusion impairment. This study aimed to investigate the association among whole-brain plaque features, perfusion deficit, and stroke recurrence.

MATERIALS AND METHODS

Patients with ischemic stroke due to intracranial atherosclerosis were retrospectively collected and categorized into first-time and recurrent-stroke groups. Patients underwent high-resolution vessel wall imaging and DSC-PWI. Intracranial plaque number, culprit plaque features (such as plaque volume/burden, degree of stenosis, enhancement ratio), and perfusion deficit variables were recorded. Logistic regression analyses were performed to determine the independent factors associated with recurrent stroke.

RESULTS

One hundred seventy-five patients (mean age, 59 [SD, 12] years; 115 men) were included. Compared with the first-time stroke group (n = 100), the recurrent-stroke group (n = 75) had a larger culprit volume (P = .006) and showed more intracranial plaques (P < .001) and more enhanced plaques (P = .003). After we adjusted for other factors, culprit plaque volume (OR, 1.16 per 10-mm³ increase; 95% CI, 1.03-1.30; P = .015) and total plaque number (OR, 1.31; 95% CI, 1.13-1.52; P < .001) were independently associated with recurrent stroke. Combining these factors increased the area under the curve to 0.71.

CONCLUSIONS

Large culprit plaque and more intracranial plaques were independently associated with recurrent stroke. Performing whole-brain vessel wall imaging may help identify patients with a higher risk of recurrent stroke.

Multi-Planar, Multi-Contrast and Multi-Time Point Analysis Tool (MOCHA) for Intracranial Vessel Wall Characterization

BACKGROUND

Three-dimensional (3D) intracranial vessel wall (IVW) magnetic resonance imaging can reliably image intracranial atherosclerotic disease (ICAD). However, an integrated, streamlined, and optimized workflow for IVW analysis to provide qualitative and quantitative measurements is lacking.

PURPOSE

To propose and evaluate an image analysis pipeline (MOCHA) that can register multicontrast and multitime point 3D IVW for multiplanar review and quantitative plaque characterization.

STUDY TYPE

Retrospective.

POPULATION

A total of 11 subjects with ICAD (68 ± 10 years old, 6 males).

FIELD STRENGTH/SEQUENCE

A 3.0 T, 3D time-of-flight gradient echo sequence and T1- and proton density-weighted fast spin echo sequences.

ASSESSMENT

Each participant underwent two IVW sessions within 2 weeks. Scan and rescan IVW images were preprocessed using MOCHA. The presence of atherosclerotic lesions was identified in different intracranial arterial segments by two readers (GC and JS, 12 years of vascular MR imaging experience each) following an established review protocol to reach consensus on each of the reviews. For all locations with identified plaques, plaque length, lumen and vessel wall areas, maximum and mean wall thickness values, normalized wall index and contrast enhancement ratio were measured.

STATISTICAL TESTS

Percent agreement and Cohen's κ were used to test scan-rescan reproducibility of detecting plaques using MOCHA. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were used to evaluate scan-rescan reproducibility for plaque morphologic and enhancement measurements.

RESULTS

In 150 paired intracranial vessel segments, the overall agreement in plaque detection was 92.7% (κ = 0.822). The ICCs (all ICCs > 0.90) and Bland-Altman plots (no bias observed) indicated excellent scan-rescan reproducibility for all morphologic and enhancement measurements.

DATA CONCLUSION

Findings from this study demonstrate that MOCHA provides high scan-rescan reproducibility for identification and quantification of atherosclerosis along multiple intracranial arterial segments and highlight its potential use in characterizing plaque composition and monitoring plaque development.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY: Stage 2.

Applying Machine Learning to Carotid Sonographic Features for Recurrent Stroke in Patients With Acute Stroke

BACKGROUND

Although carotid sonographic features have been used as predictors of recurrent stroke, few large-scale studies have explored the use of machine learning analysis of carotid sonographic features for the prediction of recurrent stroke.

METHODS

We retrospectively collected electronic medical records of enrolled patients from the data warehouse of China Medical University Hospital, a tertiary medical center in central Taiwan, from January 2012 to November 2018. We included patients who underwent a documented carotid ultrasound within 30 days of experiencing an acute first stroke during the study period. We classified these participants into two groups: those with non-recurrent stroke (those who has not been diagnosed with acute stroke again during the study period) and those with recurrent stoke (those who has been diagnosed with acute stroke during the study period). A total of 1,235 carotid sonographic parameters were analyzed. Data on the patients' demographic characteristics and comorbidities were also collected. Python 3.7 was used as the programming language, and the scikit-learn toolkit was used to complete the derivation and verification of the machine learning methods.

RESULTS

In total, 2,411 patients were enrolled in this study, of whom 1,896 and 515 had non-recurrent and recurrent stroke, respectively. After extraction, 43 features of carotid sonography (36 carotid sonographic parameters and seven transcranial color Doppler sonographic parameter) were analyzed. For predicting recurrent stroke, CatBoost achieved the highest area under the curve (0.844, CIs 95% 0.824-0.868), followed by the Light Gradient Boosting Machine (0.832, CIs 95% 0.813-0.851), random forest (0.819, CIs 95% 0.802-0.846), support-vector machine (0.759, CIs 95% 0.739-0.781), logistic regression (0.781, CIs 95% 0.764-0.800), and decision tree (0.735, CIs 95% 0.717-0.755) models.

CONCLUSION

When using the CatBoost model, the top three features for predicting recurrent stroke were determined to be the use of anticoagulation medications, the use of NSAID medications, and the resistive index of the left subclavian artery. The CatBoost model demonstrated efficiency and achieved optimal performance in the predictive classification of non-recurrent and recurrent stroke.

Intracranial Atherosclerotic Plaque Characteristics and Burden Associated With Recurrent Acute Stroke: A 3D Quantitative Vessel Wall MRI Study

Background: Intracranial atherosclerotic disease (ICAD) tends to affect multiple arterial segments, and previous studies rarely performed a comprehensive plaque analysis of the entire circle of Willis for the evaluation of recurrent stroke risk. We aimed to investigate the features of circle of Willis ICAD on 3D magnetic resonance vessel wall imaging (MR-VWI) and their relationships with recurrent acute stroke. Methods: Patients with either acute ischemic stroke (within 4 weeks after stroke) or chronic ischemic stroke (after 3 months of stroke) due to intracranial atherosclerotic plaque underwent 3D contrast-enhanced MR-VWI covering major cerebral arteries. Participants were divided into three groups: first-time acute stroke, recurrent acute stroke, and chronic stroke. Culprit plaque (defined as the only lesion or the most stenotic lesion when multiple plaques were present within the same vascular territory of the stroke) and non-culprit plaque characteristics, including total plaque number, plaque thickness, plaque area, plaque burden (calculated as plaque area divided by outer wall area), enhancement ratio (ER), eccentricity, and stenosis, were measured and compared across the three groups. Associations between plaque characteristics and recurrent acute stroke were investigated by multivariate analysis. Results: A total of 176 participants (aged 61 ± 10 years, 109 men) with 702 intracranial plaques were included in this study. There were 80 patients with first-time acute stroke, 42 patients with recurrent acute stroke, and 54 patients with chronic stroke. More intracranial plaques were found per patient in the recurrent acute stroke group than in the first-time acute stroke or chronic stroke group (5.19 ± 1.90 vs. 3.71 ± 1.96 and 3.46 ± 1.33, p < 0.001). Patients in the recurrent acute stroke group had greater culprit plaque burden (p < 0.001) and higher culprit ER (p < 0.001) than the other two groups. After adjustment of clinical demographic factors, in multivariate analysis, coronary artery disease (CAD) (odds ratio, OR = 4.61; p = 0.035), total plaque number (OR = 1.54; p = 0.003), culprit plaque ER (OR = 2.50; p = 0.036), and culprit plaque burden (OR per 10% increment = 2.44; p = 0.010) were all independently associated with recurrent acute stroke compared to the first-time acute stroke. Conclusion: Increased intracranial atherosclerotic plaque number, higher culprit plaque ER, greater culprit plaque burden, and CAD are independently associated with recurrent acute stroke.