CTA collateral status and response to recanalization in patients with acute ischemic stroke

A comprehensive review for artificial intelligence on neuroimaging in rehabilitation of ischemic stroke

Stroke is the second leading cause of death worldwide, with ischemic stroke accounting for a significant proportion of morbidity and mortality among stroke patients. Ischemic stroke often causes disability and cognitive impairment in patients, which seriously affects the quality of life of patients. Therefore, how to predict the recovery of patients can provide support for clinical intervention in advance and improve the enthusiasm of patients for rehabilitation treatment. With the popularization of imaging technology, the diagnosis and treatment of ischemic stroke patients are often accompanied by a large number of imaging data. Through machine learning and Deep Learning, information from imaging data can be used more effectively. In this review, we discuss recent advances in neuroimaging, machine learning, and Deep Learning in the rehabilitation of ischemic stroke.

Infarct Evolution on MR-DWI After Thrombectomy in Acute Stroke Patients Randomized to Nerinetide or Placebo: The REPERFUSE-NA1 Study

BACKGROUND AND OBJECTIVES

The neuroprotectant nerinetide has shown promise in reducing infarct volumes in primate models of ischemia reperfusion. We hypothesized that early secondary infarct growth after endovascular therapy (EVT) (1) may be a suitable surrogate biomarker for testing neuroprotective compounds, (2) is feasible to assess in the acute setting using sequential MRI, and (3) can be modified by treatment with nerinetide.

METHODS

REPERFUSE-NA1 was a prospective, multisite MRI substudy of the randomized controlled trial ESCAPE-NA1 (ClinicalTrials.gov NCT02930018) that involved patients with acute disabling large vessel occlusive stroke undergoing EVT within 12 hours of onset who were randomized to receive intravenous nerinetide or placebo. Patients enrolled in REPERFUSE-NA1 underwent sequential MRI <5 hours post-EVT (day 1) and at 24 hours (day 2). The primary outcome was total diffusion-weighted MRI infarct growth early after EVT, defined as the lesion volume difference between day 2 and day 1. The secondary outcome was region-specific infarct growth in different brain tissue compartments. Statistical analyses were performed using the Mann-Whitney U test and multiple linear regression.

RESULTS

Sixty-seven of 71 patients included had MRI of sufficient quality. The median infarct volume post-EVT was 12.98 mL (IQR, 5.93-28.08) in the nerinetide group and 10.80 mL (IQR, 3.11-24.45) in the control group (p = 0.59). Patients receiving nerinetide showed a median early secondary infarct growth of 5.92 mL (IQR, 1.09-21.30) compared with 10.80 mL (interquartile range [IQR], 2.54-21.81) in patients with placebo (p = 0.30). Intravenous alteplase modified the effect of nerinetide on region-specific infarct growth in white matter and basal ganglia compartments. In patients with no alteplase, the infarct growth rate was reduced by 120% (standard error [SE], 60%) in the white matter (p = 0.03) and by 340% (SE, 140%) in the basal ganglia (p = 0.02) in the nerinetide group compared with placebo after adjusting for confounders.

DISCUSSION

This study highlights the potential of using MR imaging as a biomarker to estimate the effect of a neuroprotective agent in acute stroke treatment. Patients with acute large vessel occlusive stroke exhibited appreciable early infarct growth both in the gray matter and the white matter after undergoing EVT. Acknowledging relatively small overall infarct volumes in this study, treatment with nerinetide was associated with slightly reduced percentage infarct growth in the white matter and basal ganglia compared with placebo in patients not receiving intravenous alteplase and had no effect on the total early secondary infarct growth.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov NCT02930018.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with acute large vessel ischemic stroke undergoing EVT, nerinetide did not significantly decrease early post-EVT infarct growth compared with placebo.

Enhancing the clinical value of single-phase computed tomography angiography in the assessment of collateral circulation in acute ischemic stroke: A narrative review

Acute ischemic stroke (AIS) condition assessment and clinical prognosis are significantly influenced by the compensatory state of cerebral collateral circulation. A standard clinical test known as single-phase computed tomography angiography (sCTA) is useful for quickly and accurately assessing the creation or opening of cerebral collateral circulation, which is crucial for the diagnosis and treatment of AIS. To improve the clinical application of sCTA in the clinical assessment of collateral circulation, we examine the present use of sCTA in AIS in this work.

The negative effect of aging on cerebral venous outflow in acute ischemic stroke

Cortical venous outflow (VO) represents an imaging biomarker of increasing interest in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). We conducted a retrospective multicenter cohort study to investigate the effect of aging on VO. A total of 784 patients met the inclusion criteria. Cortical Vein Opacification Score (COVES) was used to assess VO profiles on admission CT angiography. Cerebral microperfusion was determined using the hypoperfusion intensity ratio (HIR) derived from perfusion imaging. Arterial collaterals were assessed using the Tan scale. Multivariable regression analysis was performed to identify independent determinants of VO, HIR and arterial collaterals. In multivariable regression, higher age correlated with worse VO (adjusted odds ratio [95% CI]; 0.83 [0.73-0.95]; P = 0.006) and poorer HIR (β coefficient [95% CI], 0.014 [0.005-0.024]; P = 0.002). The negative effect of higher age on VO was mediated by the extent of HIR (17.3%). We conclude that higher age was associated with worse VO in AIS-LVO, partially explained by the extent of HIR reflecting cerebral microperfusion. Our study underlines the need to assess collateral blood flow beyond the arterial system and provides valuable insights into deteriorated cerebral blood supply in elderly AIS-LVO patients.

Collateral Status Modification of the Association Between Blood Pressure Variation Within 72 Hours After Endovascular Treatment and Clinical Outcome in Acute Ischemic Stroke: A Retrospective Cohort Study

Background

Blood pressure variation and collateral status have been reported to be associated with clinical outcome in patients with acute ischemic stroke who received endovascular treatment; however, the relationship between blood pressure variation within 72 hours after EVT and clinical outcome in different collateral status remains unclear.

Methods

Acute ischemic stroke patients due to large vessel occlusion with EVT were retrospectively enrolled. We classified participants into poor collateral (ASITN/SIR grade <2) and good collateral subgroups (ASITN/SIR grade ≥2). The primary outcome was unfavorable neurological outcome defined as a 3-month modified Rankin Scale (mRS) score ≥2. The interactive effect was tested to determine the influence of collateral status on the association between BP variation and clinical outcome.

Results

A total of 545 patients were included. The poor collateral subgroup was detected in 198 patients with an average age of 70.2 years. The association between BP variation and primary outcome did not differ under different collateral status (P for interaction >0.05). However, the association between the mean and coefficient of variation (CV) values of DBP and 3-month mortality was significantly discrepant under different collateral status (P for interaction <0.05). In the good collateral subgroup, higher mean DBP was associated with a lower risk of 3-month mortality (OR 0.95, 95% CI 0.91-1, P = 0.033) compared with the poor subgroup (OR 1.04, 95% CI 0.97-1.1, P = 0.286). In addition, a higher CV of DBP was associated with a higher risk of 3-month mortality (OR 1.24, 95% CI 1.13-1.36, P < 0.01) compared with poor status (OR 1.08, 95% CI 0.94-1.23, P=0.275).

Conclusion

For patients who received EVT with good collateral status, increased CV of DBP was significantly associated with higher 3-month mortality, while higher mean DBP within 72 h after EVT was associated with a decrease in 3-month mortality.

Unfavorable cerebral venous outflow is associated with futile recanalization in acute ischemic stroke patients

BACKGROUND AND PURPOSE

Mechanical thrombectomy (MT) has proven to be the standard of care for patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). However, high revascularization rates do not necessarily result in favorable functional outcomes. We aimed to investigate imaging biomarkers associated with futile recanalization, defined as unfavorable functional outcome despite successful recanalization in AIS-LVO patients.

METHODS

A retrospective multicenter cohort study was made of AIS-LVO patients treated by MT. Successful recanalization was defined as modified Thrombolysis in Cerebral Infarction score of 2b-3. A modified Rankin Scale score of 3-6 at 90 days was defined as unfavorable functional outcome. Cortical Vein Opacification Score (COVES) was used to assess venous outflow (VO), and the Tan scale was utilized to determine pial arterial collaterals on admission computed tomography angiography (CTA). Unfavorable VO was defined as COVES ≤ 2. Multivariable regression analysis was performed to investigate vascular imaging factors associated with futile recanalization.

RESULTS

Among 539 patients in whom successful recanalization was achieved, unfavorable functional outcome was observed in 59% of patients. Fifty-eight percent of patients had unfavorable VO, and 31% exhibited poor pial arterial collaterals. In multivariable regression, unfavorable VO was a strong predictor (adjusted odds ratio = 4.79, 95% confidence interval = 2.48-9.23) of unfavorable functional outcome despite successful recanalization.

CONCLUSIONS

We observe that unfavorable VO on admission CTA is a strong predictor of unfavorable functional outcomes despite successful vessel recanalization in AIS-LVO patients. Assessment of VO profiles could help as a pretreatment imaging biomarker to determine patients at risk for futile recanalization.

Under (back) pressure: Better collateral flow may facilitate clot removal in ischemic stroke: A systematic review and meta-analysis

BACKGROUND

Collateral status may facilitate clot removal and affect rates of successful reperfusion following endovascular therapy (EVT) for acute ischemic stroke (AIS).

METHODS

Following the PRISMA guidelines, a systematic literature review of the English language literature was conducted using PubMed, Scopus, Web of Science, and Embase. Papers which focused on collateral status and patients treated with EVT for AIS were included in our analysis. Outcomes of interest included collateral score grading, rates of successful reperfusion defined as thrombolysis in cerebral infarction (TICI) score 2b-3 and onset to revascularization time. We calculated pooled odds ratio (OR) or mean difference (MD) and their corresponding 95% confidence intervals (CI) based on collateral status.

RESULTS

16 studies, with 6073 patients, were included in our analysis. Among the included studies, there were six different collateral grading scales, which were dichotomized into "good to moderate" and "poor" collaterals. Odds of successful reperfusion were significantly higher among patients with good to moderate collateral circulation compared to those with poor collaterals (OR =  1.61; 95% CI = 1.24 to 2.09; P-value < 0.001); however, there was heterogeneity among included studies (I2= 5 4%; P-value = 0.008). Onset to revascularization time was comparable between patients with good to moderate collateral circulation compared to those with poor collaterals (MD = 3.91 min; 95% CI = -8.71 to 16.53; P-value = 0.544); however, there was heterogeneity among included studies (I2= 60%; P-value = 0.014).

CONCLUSIONS

The presence of good collaterals may increase the odds of achieving successful reperfusion following EVT for AIS. Improved collateral flow was associated with improved angiographic outcomes, although future work is needed to determine if a causal relationship exists.

Prognostic significance of blood pressure parameters after mechanical thrombectomy according to collateral status

BACKGROUND

Mechanical thrombectomy (MT) has been proven as an effective and safe therapy for patients with acute ischemic stroke from large vessel occlusion. However, there is still a controversial topic about post-procedural management including blood pressure (BP).

METHODS

A total of 294 patients who received MT in Second Affiliated Hospital of Soochow University from April 2017 to September 2021 were included consecutively. The association of blood pressure parameters (BPV and hypotension time) with poor functional outcome was evaluated using logistic regression models. Meanwhile, the effects of BP parameters on mortality was analyzed using cox proportional hazards regression models. Furthermore, the corresponding multiplicative term was added to the above models to study the interaction between BP parameters and CS.

RESULTS

Two hundred ninety four patients were included finally. The mean age was 65.5 years. At the 3-month follow-up, 187(61.5%) had poor functional outcome and 70(23.0%) died. Regardless of the CS, BP CV is positively associated with poor outcome. Hypotension time was negatively associated with poor outcome. We conducted a subgroup analysis according to CS. BPV was significantly associated with mortality at 3-month and displayed a trend toward poor outcome for patients with poor CS only. The interaction between SBP CV and CS with respect to mortality after adjusting for confounding factors was statistically significant (P for interaction = 0.025) and the interaction between MAP CV and CS with respect to mortality after multivariate adjustment was also statistically significant (P for interaction = 0.005).

CONCLUSION

In MT-treated stroke patients, higher BPV in the first 72 h is significantly associated with poor functional outcome and mortality at 3-month regardless of CS. This association was also found for hypotension time. Further analysis showed CS modified the association between BPV and clinical prognosis. BPV displayed a trend toward poor outcome for patients with poor CS.

The impact of leptomeningeal collaterals in acute ischemic stroke: a systematic review and meta-analysis

OBJECTIVES

Leptomeningeal collaterals provide an alternate pathway to maintain cerebral blood flow in stroke to prevent ischemia, but their role in predicting the outcome is still unclear. So, our study aims at assessing the significance of collateral blood flow (CBF) in acute stroke.

METHODS

Electronic databases were searched under different MeSH terms from January 2000 to February 2019. Studies were included if there was available data on good and poor CBF in acute ischemic stroke (AIS). The clinical outcomes included were modified Rankin scale (mRS), recanalization, mortality, and symptomatic intracranial hemorrhage (sICH) at 90 days. Data was analyzed using a random-effect model.

RESULTS

A total of 47 studies with 8194 patients were included. Pooled meta-analysis revealed that there exist twofold higher likelihood of favorable clinical outcome (mRS ≤ 2) at 90 days with good CBF compared with poor CBF (RR: 2.27; 95% CI: 1.94-2.65; p < 0.00001) irrespective of the thrombolytic therapy [RR with IVT: 2.90; 95% CI: 2.14-3.94; p < 0.00001, and RR with IAT/EVT: 1.99; 95% CI: 1.55-2.55; p < 0.00001]. Moreover, there exists onefold higher probability of successful recanalization with good CBF (RR: 1.31; 95% CI: 1.15-1.49; p < 0.00001). However, there was 54% and 64% lower risk of sICH and mortality respectively in patients with good CBF in AIS (p < 0.00001).

CONCLUSIONS

The relative risk of favorable clinical outcome is more in patients with good pretreatment CBF. This could be explained due to better chances of recanalization combined with a lesser risk of intracerebral hemorrhage with good CBF status.

Prognostic accuracy and impact of cerebral collateral status on clinical and safety outcomes in acute ischemic stroke patients receiving reperfusion therapy: a systematic meta-analysis

BACKGROUND

Cerebral collateral status has a potential role in mediating postreperfusion clinical and safety outcomes in acute ischemic stroke (AIS).

PURPOSE

To investigate the prognostic accuracy and impact of collateral status on clinical and safety outcomes in patients with AIS receiving reperfusion therapy.

MATERIAL AND METHODS

Studies with AIS patients treated with reperfusion therapy, collateral status assessed using Tan, ASITN/SIR, or similar collateral grading methods and data stratified according to collateral status were included. Relevant data on clinical outcomes, such as functional outcome at 90 days, mortality at 90 days, angiographic reperfusion, symptomatic intracerebral hemorrhage (sICH) and hemorrhagic transformation (HT), were collated and analyzed.

RESULTS

A meta-analysis of 18 studies involving 4132 patients with AIS was conducted. Good collateral status was significantly associated with angiographic reperfusion (odds ratio [OR]=1.97, 95% confidence interval [CI]=1.38-2.80; P < 0.0001), sICH (OR=0.67, 95% CI=0.46-0.99; P = 0.042), and 90-day functional outcome (OR=3.05, 95% CI=1.78-5.24; P < 0.0001). However, its association with HT (OR=0.76, 95% CI=0.38-1.51; P = 0.425) and three-month mortality (OR=0.53, 95% CI=0.17-1.69; P = 0.280) did not reach statistical significance. The prognostic accuracy of collaterals for predicting angiographic reperfusion, HT, functional outcome (at 90 days), and mortality (at 90 days) were 63%, 49%, 66%, and 48%, respectively.

CONCLUSION

Cerebral collaterals are significantly associated with clinical and safety outcomes, albeit with a prognostic accuracy range of 48%-66%; thus, evaluation of their patency is a useful prognostic tool in patients with AIS receiving reperfusion therapy.

Comparison between collateral status and DEFUSE 3 or DAWN criteria in patient selection for endovascular thrombectomy within 6-24 hours after stroke: a protocol for meta-analysis

INTRODUCTION

Perfusion imaging according to the DEFUSE 3 or DAWN criteria has been applied to select patients with large vascular occlusive stroke undergo endovascular therapy (EVT) in the extended time window. Emerging studies have shown that collateral blood flow-based criteria may be as effective as DEFUSE 3 and DAWN criteria for the evaluation of EVT eligibility beyond 6 hours. We will conduct a meta-analysis to compare collateral status-based criteria with DEFUSE 3 or DAWN criteria.

METHODS AND ANALYSIS

We will conduct a search for the studies comparing collateral blood flow-based imaging with CT perfusion using the DEFUSE 3 or DAWN criteria in selecting patients with acute ischaemic stroke undergo EVT in the Web of Science, PubMed, EMBASE and the Cochrane Library databases between November 2017 and November 2021. We will also search the sources of grey literature, the reference lists of included studies and the newly published studies during the review period. Two investigators will independently screen the eligible studies and extract data. The study quality will be assessed by using the Newcastle-Ottawa Scale or the Cochrane risk bias tool. Stata V.17 will be used to conduct data analysis.

ETHICS AND DISSEMINATION

Patient informed consent and ethics approval are not necessary as this study uses only published studies. The finding of this meta-analysis will be propagated through committee conferences or peer-reviewed journals.

PROSPERO REGISTRATION NUMBER

CRD42021281928.

MR Angiography in Assessment of Collaterals in Patients with Acute Ischemic Stroke: A Comparative Analysis with Digital Subtraction Angiography

Collateral status has prognostic and treatment implications in acute ischemic stroke (AIS) patients. Unlike CTA, grading collaterals on MRA is not well studied. We aimed to evaluate the accuracy of assessing collaterals on pretreatment MRA in AIS patients against DSA. AIS patients with anterior circulation proximal arterial occlusion with baseline MRA and subsequent endovascular treatment were included. MRA collaterals were evaluated by two neuroradiologists independently using the Tan and Maas scoring systems. DSA collaterals were evaluated by using the American Society of Interventional and Therapeutic Neuroradiology grading system and were used as the reference for comparative analysis against MRA. A total of 104 patients met the inclusion criteria (59 female, age (mean ± SD): 70.8 ± 18.1). The inter-rater agreement (k) for collateral scoring was 0.49, 95% CI 0.37–0.61 for the Tan score and 0.44, 95% CI 0.26–0.62 for the Maas score. Total number (%) of sufficient vs. insufficient collaterals based on DSA was 49 (47%) and 55 (53%) respectively. Using the Tan score, 45% of patients with sufficient collaterals and 64% with insufficient collaterals were correctly identified in comparison to DSA, resulting in a poor agreement (0.09, 95% CI 0.1–0.28). Using the Maas score, only 4% of patients with sufficient collaterals and 93% with insufficient collaterals were correctly identified against DSA, resulting in poor agreement (0.03, 95% CI 0.06–0.13). Pretreatment MRA in AIS patients has limited concordance with DSA when grading collaterals using the Tan and Maas scoring systems.

Circle of Willis variation and outcome after intra-arterial treatment

Background

Intra-arterial treatment (IAT) improves outcomes in acute ischaemic stroke. Presence of collaterals increases likelihood of good outcome. We investigated whether variations in the circle of Willis (CoW) and contributing carotid arteries influence outcome in patients who had a stroke treated with IAT.

Methods

CT angiography data on patients who had an acute stroke treated with IAT were retrospectively collected. CoW was regarded complete if the contralateral A1 segment, anterior communicating artery and ipsilateral posterior communicating artery were fully developed, and the P1 segment was visible. Carotid artery contribution was studied with a self-developed carotid artery score ranging from 0 to 2 depending on the number of arteries supplying the occluded side of the CoW. Good clinical outcome was defined as modified Rankin Score ≤2 and measured at discharge and 3 months. We calculated risk ratios for the relation between completeness of the CoW, carotid score and good outcome, and performed a trend analysis for good outcome according to the carotid score.

Results

126 patients were included for analysis. Patients with a complete and incomplete CoW had a comparable risk for good outcome at discharge and 3 months. A higher carotid score was associated with a higher likelihood of good clinical outcome (p for trend 0.24 at discharge and 0.05 at 3 months).

Conclusion

In patients with acute ischaemic stroke treated with IAT, chances of good clinical outcome tended to improve with number of carotid arteries supplying the cerebral circulation. Completeness of the CoW was not related to clinical outcome.

Cerebral Collateral Circulation in the Era of Reperfusion Therapies for Acute Ischemic Stroke

Clinical outcomes of patients with acute ischemic stroke depend in part on the extent of their collateral circulation. A good collateral circulation has also been associated with greater benefit of intravenous thrombolysis and endovascular treatment. Treatment decisions for these reperfusion therapies are increasingly guided by a combination of clinical and imaging parameters, particularly in later time windows. Computed tomography and magnetic resonance imaging enable a rapid assessment of both the collateral extent and cerebral perfusion. Yet, the role of the collateral circulation in clinical decision-making is currently limited and may be underappreciated due to the use of rather coarse and rater-dependent grading methods. In this review, we discuss determinants of the collateral circulation in patients with acute ischemic stroke, report on commonly used and emerging neuroimaging techniques for assessing the collateral circulation, and discuss the therapeutic and prognostic implications of the collateral circulation in relation to reperfusion therapies for acute ischemic stroke.

Detection, Diagnosis and Treatment of Acute Ischemic Stroke: Current and Future Perspectives

Stroke is one of the leading causes of disability worldwide. Early diagnosis and treatment of stroke are important for better clinical outcome. Rapid and accurate diagnosis of stroke subtypes is critical. This review discusses the advantages and disadvantages of the current diagnostic and assessment techniques used in clinical practice, particularly for diagnosing acute ischemic stroke. Alternative techniques for rapid detection of stroke utilizing blood based biomarkers and novel portable devices employing imaging methods such as volumetric impedance phase-shift spectroscopy, microwave tomography and Doppler ultrasound are also discussed. Current therapeutic approaches for treating acute ischemic stroke using thrombolytic drugs and endovascular thrombectomy are discussed, with a focus on devices and approaches recently developed to treat large cranial vessel occlusions.

Collateral status and recanalization after endovascular treatment for acute ischemic stroke

BACKGROUND

Successful recanalization and good collateral status are associated with good clinical outcomes after endovascular treatment (EVT) for acute ischemic stroke, but the relationships among them are unclear.

OBJECTIVE

To assess if collateral status is associated with recanalization after EVT and if collateral status modifies the association between successful recanalization and functional outcome.

METHODS

We retrospectively analyzed data from the MR CLEAN Registry, a multicenter prospective cohort study of patients with a proximal anterior occlusion who underwent EVT in the Netherlands. We determined collateral status with a previously validated four-point visual grading scale and defined successful recanalization as an extended Thrombolysis in Cerebral Infarction score ≥2B. Functional outcome was determined using the modified Rankin Scale score at 90 days. We assessed, with multivariable logistic regression models, the associations between (1) collateral status and successful recanalization, (2) successful recanalization and functional outcome, (3) collateral status and functional outcome. An interaction of collateral status and successful recanalization was assessed. Subgroup analyses were performed for patients treated with intravenous thrombolysis.

RESULTS

We included 2717 patients, of whom 1898 (70%) had successful recanalization. There was no relationship between collateral status and successful recanalization (adjusted common OR (95% CI) of grades 1, 2, and 3 vs 0: 1.19 (0.82 to 1.72), 1.20 (0.83 to 1.75), and 1.10 (0.74 to 1.63), respectively). Successful recanalization (acOR (95% CI): 2.15 (1.84 to 2.52)) and better collateral grades (acOR (95% CI) of grades 1, 2, and 3 vs 0: 2.12 (1.47 to 3.05), 3.46 (2.43 to 4.92), and 4.16 (2.89 to 5.99), respectively) were both associated with a shift towards better functional outcome, without an interaction between collateral status and successful recanalization. Results were similar for the subgroup of thrombolysed patients.

CONCLUSIONS

Collateral status is not associated with the probability of successful recanalization after EVT and does not modify the association between successful recanalization and functional outcome.

Association of Systolic Blood Pressure and Cerebral Collateral Flow in Acute Ischemic Stroke by Stroke Subtype

Background and Purpose

Collateral flow in acute ischemic stroke is known as a predictor of treatment outcome and long-term prognosis. However, factors determining the initial collateral flow remain unclear. We investigated factors related to collateral flow in patients with acute ischemic stroke caused by large vessel occlusion (AIS-LVO) and further analyzed the results according to stroke etiology.

Methods

This was a retrospective study using prospective stroke registry data from a single university hospital from October 2014 to May 2021. AIS-LVO with middle cerebral artery M1 occlusion identified by pre-treatment multiphasic computed tomography angiography was included. Collateral flow score was graded on a 6-point ordinal scale according to pial arterial filling.

Results

A total of 74 patients [cardioembolism (CE): 57; large artery atherosclerosis (LAA): 17] was included. The mean age of all patients was 72.2 ± 11.7 years, and 37.8 % (n = 28) were men. Multivariate regression analysis showed that initial SBP [odds ratio (OR): 0.994; 95% confidence interval (CI): 0.990–0.998; p = 0.002] and stroke etiology (OR: 0.718; 95% CI: 0.548–0.940; p = 0.019) were independent factors of the collateral flow grade. Collateral flow grade was independently associated with initial SBP in the CE group (OR: 0.993; 95% CI: 0.989–0.998; p = 0.004) but not in the LAA group (OR: 0.992; 95% CI: 0.980–1.004; p = 0.218). Initial SBP was significantly correlated with NIHSS score in the CE group but not in the LAA group (r²= 0.091, p = 0.023; r² = 0.043, p = 0.426, respectively).

Conclusions

Elevated initial SBP was associated with poor cerebral collateral flow and more severe symptoms in the CE group, but not in the LAA group in patients with AIS-LVO. These findings suggest differential effects of initial SBP elevation on collateral flow by stroke subtypes.

Diagnostic test accuracy of pretreatment collateral score in predicting stroke outcomes after intra-arterial endovascular thrombectomy: a meta-analysis in DSA and CTA

OBJECTIVES

This study compared the diagnostic accuracy of pretreatment circulation collateral scoring (CS) system using digital subtraction angiography (DSA) and computed tomography angiography (CTA) in predicting favorable functional outcome (FFO) after intra-arterial endovascular thrombectomy (IA-EVT). Subgroup analysis characterizing scoring systems within each category was additionally conducted.

MATERIALS AND METHODS

We performed a diagnostic meta-analysis to assess the sensitivity and specificity of each CS system by using DSA and CTA, respectively. The hierarchical summary receiver operating characteristic curve (HSROC) models were used to estimate the diagnostic odds ratio (DOR) and area under the curve (AUC). The Bayes theorem was employed to determine posttest probability (PTP).

RESULTS

In total, 14 and 21 studies were assessed with DSA and CTA, respectively. In DSA, the pooled sensitivity and specificity were 0.72 (95% CI, 0.63-0.79) and 0.61 (0.53-0.68), respectively, and in the HSROC model, the DOR was 3.94 (2.71-5.73), and the AUC was 0.71 (90.67-0.75). CTA revealed a pooled sensitivity and specificity of 0.74 (0.64-0.82) and 0.53 (0.44-0.62), respectively, and in the HSROC model, the DOR was 3.17 (2.34-4.50), and the AUC was 0.67 (0.63-0.71). With a pretest probability of 26.3%, the CS in DSA and CTA exhibited limited increase of PTPs of 39% and 36%, respectively, in detecting the FFO on day 90.

CONCLUSION

DSA and CTA have comparable accuracy and are limited in predicting the functional outcome. The collateral score systems assessed with DSA and CTA were more suitable for screening than diagnosis for patients before IA-EVT.

KEY POINTS

• Our study revealed the differences of various scoring systems for assessing collateral status. • DSA and CTA have comparable accuracy, but both imaging modalities played relatively limited roles in predicting functional outcome on day 90. • The collateral score systems assessed with DSA and CTA were more suitable for screening than diagnosis for patients before IA-EVT.

Collateral Status and Clinical Outcomes after Mechanical Thrombectomy in Patients with Anterior Circulation Occlusion

Background. Successful mechanical thrombectomy (MT) requires reliable, noninvasive selection criteria. We aimed to investigate the association of collateral status and clinical outcomes after MT in patients with ischemic stroke due to anterior circulation occlusion. Methods. 109 patients with poor collaterals and 110 aged, sex-matched patients with good collaterals were enrolled in the study. Collateral circulation was estimated by the CT angiography with a 0–3 scale. The collateral status was categorized as poor collaterals (scores 0–1) and good collaterals (scores 2-3). The reperfusion was assessed by the modified Treatment in Cerebral Infarction scale (mTICI, score 0/1/2a/2b/3). The clinical outcomes included the scores on the modified Rankin scale (mRS, ranging from 0 to 6) and death 90 days after mechanical thrombectomy. Results. Patients with greater scores of collateral status were more likely to achieve successful reperfusion (mTICI 2b/3). Patients with good collaterals were significantly associated with a higher chance of achieving mRS of 0–1 at 90 days (adjusted ORs: 4.55; 95% CI: 3.17–7.24; and $P$  < 0.001) and a lower risk of death at 90 days (adjusted ORs: 0.87; 95% CI: 4.0%–28.0%; and $P$  = 0.012) compared to patients with poor collaterals. In subgroup analyses, patients with statin use seem to benefit more from the effect of collateral status on good mRS (≤2). Conclusion. Among patients with acute ischemic stroke caused by anterior circulation occlusion, better collateral status is associated with higher scores on mRS and lower mortality after mechanical thrombectomy. Statin use might have an interaction with the effect of collateral status.

OUP accepted manuscript

The recanalization effect of large-vessel occlusion (LVO) in anterior circulation is well documented but only some patients benefit from endovascular treatment. We analysed clinical and radiological factors determining clinical outcome after successful mechanical intervention. We included 146 patients from the Prague 16 study enrolled from September 2012 to December 2020, who had initial CT/CTA examination and achieved good recanalization status after mechanical intervention (TICI 2b-3). One hundred and six (73%) patients achieved a good clinical outcome (modified Rankin Scale 0–2 in 3 months). It was associated with age, leptomeningeal collaterals (LC), onset to intervention time, ASPECTS, initial NIHSS, and leukoaraiosis (LA) in univariate analysis. The regression model identified good collateral status [odds ratio (OR) 5.00, 95% confidence interval (CI) 1.91–13.08], late thrombectomy (OR 0.24, 95% CI 0.09–0.65), LA (OR 0.44, 95% CI 0.19–1.00), ASPECTS (OR 1.45, 95% CI 1.08–1.95), and NIHSS score (OR 0.86, 95% CI 0.78–0.95) as independent outcome determinants. In the late thrombectomy subgroup, 14 out of 33 patients (42%) achieved a favourable clinical outcome, none of whom with poor collateral status. The presence of LC and absence of LA predicts a good outcome in acute stroke patients after successful recanalization of LVO in anterior circulation. Late thrombectomy was associated with higher rate of unfavourable clinical outcome. Nevertheless, collateral status in this subgroup was validated as a reliable selection criterion.

Full Reperfusion Without Functional Independence After Mechanical Thrombectomy in the Anterior Circulation : Performance of Prediction Models Before Versus After Treatment Initiation

BACKGROUND AND PURPOSE

Prediction of futile recanalization (FR), i.e. failure of long-term functional independence despite full reperfusion in mechanical thrombectomy (MT), is instrumental in patients undergoing endovascular therapy.

METHODS

Retrospective single-center analysis of patients treated for anterior circulation LVO ensuing successful MT (mTICI 2c-3) between January 2014 and April 2019. FR was defined as modified Rankin Scale (mRS) 90 days after stroke onset > 2 or mRS > pre-stroke mRS. Multivariable analysis was performed with variables available before treatment initiation regarding their association with FR. Performance of the regression model was then compared with a model including parameters available after MT.

RESULTS

Successful MT was experienced by 549/1146 patients in total. FR occurred in 262/549 (47.7%) patients. Independent predictors of FR were male sex, odds ratio (OR) with 95% confidence interval (CI) 1.98 (1.31-3.05, p 0.001), age (OR 1.05, CI 1.03-1.07, p < 0.001), NIHSS on admission (OR 1.10, CI 1.06-1.13, p < 0.001), pre-stroke mRS (OR 1.22, CI 1.03-1.46, p 0.025), neutrophile-lymphocyte ratio (OR 1.03, CI 1.00-1.06, p 0.022), baseline ASPECTS (OR 0.77, CI 0.68-0.88, p < 0.001), and absence of bridging i.v. lysis (OR 1.62, 1.09-2.42, p 0.016). The prediction model's Area Under the Curve was 0.78 (CI 0.74-0.82) and increased with parameters available after MT to 0.86 (CI 0.83-0.89) with failure of early neurological improvement being the most important predictor of FR (OR 15.0, CI 7.2-33.8).

CONCLUSION

A variety of preinterventional factors may predict FR with substantial certainty, but the prediction model can still be improved by considering parameters only available after MT, in particular early neurological improvement.

Time-resolved assessment of cortical venous drainage on multiphase CT angiography in patients with acute ischemic stroke

PURPOSE

Cortical vein opacification is not routinely assessed in patients presenting with acute ischemic stroke (AIS), and the value of temporal assessment of venous outflow is not known. We evaluated the utility of assessing cortical venous drainage over time using multiphase CT angiography (mCTA).

METHODS

Cortical venous drainage was assessed in patients from the Precise and Rapid Assessment of Collaterals Using Multi-Phase CTA in the Triage of Patients With Acute Ischemic Stroke for IA Therapy prospective multicenter cohort study of patients with symptoms of AIS with ICA and/or middle cerebral artery occlusion on baseline mCTA. Opacification of vein of Labbe, sphenoparietal sinus, superficial middle cerebral vein, and vein of Trolard of the affected hemisphere was graded as no (0), partial (1), or full (2) opacification in each mCTA phase. The venous opacification scores for each phase were added to generate a total venous score (TVS) (range 0-24). Primary outcome was 90-day modified Rankin score. Repeated measures analysis was used to assess the effect of phase timing on venous score on outcome.

RESULTS

Of 432 patients, 284 (65.7%) had proximal arterial occlusions. Median venous opacification score per phase (range 0-8) was 3 (IQR 1-6) in the first phase and increased in the second and third phases [median (IQR): 6 (5-8) and 8 (6-8), respectively] of the mCTA. In a multivariable analysis adjusting for age, baseline National Institutes of Health Stroke Scale, and Alberta stroke program early CT score, a significant association between TVS and 90-day mRS was noted ([adjusted cOR for TVS 6-11: 0.16 (95% CI 0.05-0.51); TVS 12-17: 0.18 (95% CI 0.06-0.57); TVS 18-24: 0.20 (0.06-0.63)]. Repeated measures analysis of venous scores from all three phases showed a significant effect of time/phase on TVS (p < 0.001).

CONCLUSION

This study concludes that venous opacification over time on multiphase CTA is associated with 90-day clinical outcome. There was however no added benefit of venous scoring vis-a-vis arterial collateral assessment in predicting outcome.

Fifty Years of Acute Ischemic Stroke Treatment: A Personal History

BACKGROUND

It has been 50 years since the first explorations of the physiology of cerebral ischemia by measuring cerebral blood flow (CBF), and 25 years since the approval of tissue plasminogen activator for treating acute ischemic stroke. My personal career began and matured during those eras. Here, I provide my perspective on the evolution of acute stroke research and treatment from 1971 to the present, with some in-depth discussion of the National Institutes of Neurologic Disease and Stroke (NINDS) tissue-type plasminogen activator (tPA) stroke trial and development of mobile stroke units.

SUMMARY

Studies of CBF and metabolism in acute stroke patients revealed graded tissue injury that was dependent on the duration of ischemia. Subsequent animal research unraveled the biochemical cascade of events occurring at the cellular level after cerebral ischemia. After a decade of failed translation, the development of a relatively safe thrombolytic allowed us to achieve reperfusion and apply the lessons from earlier research to achieve positive clinical results. The successful conduct of the NINDS tPA stroke study coupled with positive outcomes from companion tPA studies around the world created the specialty of vascular neurology. This was followed by an avalanche of research in imaging, a focus on enhancing reperfusion through thrombectomy, and improving delivery of faster treatment culminating in mobile stroke units. Key Messages: The last half century has seen the birth and evolution of successful acute stroke treatment. More research is needed in developing new drugs and catheters to build on the advances we have already made with reperfusion and also in evolving our systems of care to get more patients treated more quickly in the prehospital setting. The history of stroke treatment over the last 50 years exemplifies that medical "science" is an evolving discipline worth an entire career's dedication. What was impossible 50 years ago is today's standard of care, what we claim as dogma today will be laughed at a decade from now, and what appears currently impossible will be tomorrow's realities.

Collateral status reperfusion and outcomes after endovascular therapy: insight from the Endovascular Treatment in Ischemic Stroke (ETIS) Registry

BACKGROUND

Studies have suggested that collateral status modifies the effect of successful reperfusion on functional outcome after endovascular therapy (EVT). We aimed to assess the association between collateral status and EVT outcomes and to investigate whether collateral status modified the effect of successful reperfusion on EVT outcomes.

METHODS

We used data from the ongoing, prospective, multicenter Endovascular Treatment in Ischemic Stroke (ETIS) Registry. Collaterals were graded according to the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) guidelines. Patients were divided into two groups based on angiographic collateral status: poor (grade 0-2) versus good (grade 3-4) collaterals.

RESULTS

Among 2020 patients included in the study, 959 (47%) had good collaterals. Good collaterals were associated with favorable outcome (90-day modified Rankin Scale (mRS) 0-2) (OR 1.5, 95% CI 1.19 to 1.88). Probability of good outcome decreased with increased time from onset to reperfusion in both good and poor collateral groups. Successful reperfusion was associated with higher odds of favorable outcome in good collaterals (OR 6.01, 95% CI 3.27 to 11.04) and poor collaterals (OR 5.65, 95% CI 3.32 to 9.63) with no significant interaction. Similarly, successful reperfusion was associated with higher odds of excellent outcome (90-day mRS 0-1) and lower odds of mortality in both groups with no significant interaction. The benefit of successful reperfusion decreased with time from onset in both groups, but the curve was steeper in the poor collateral group.

CONCLUSIONS

Collateral status predicted functional outcome after EVT. However, collateral status on the pretreatment angiogram did not decrease the clinical benefit of successful reperfusion.

Quantitative collateral assessment evaluated by cerebral blood volume measured by CT perfusion in patients with acute ischemic stroke

OBJECTIVES

Collateral status (CS) is considered a predictor of clinical outcome after reperfusion therapy (RT) in patients with acute ischemic stroke (AIS). We proposed a quantitative assessment of CS using cerebral blood volume (CBV) measured by computed tomography perfusion (CTP) imaging.

MATERIALS AND METHODS

This retrospective study was approved by the Institutional Review Board. Between February 2019 and September 2020, 60 patients with anterior circulation large-vessel occlusion who presented to our institution within 8 h after stroke onset were included. The ratio of the average CBV values in the affected middle cerebral artery (MCA) territories to the unaffected side was defined as the CBV ratio. CS was assessed by scores from previously reported qualitative scoring systems (Tan & regional leptomeningeal collateral (rLMC) scores).

RESULTS

The CBV ratio was an independent factor contributing to a good functional outcome (P<0.01) and was significantly correlated with the Tan score (ρ=0.73, P<0.01) and the rLMC score (ρ=0.77, P<0.01). Among the patients with recanalization, the CBV ratio was a useful parameter that predicted both a good functional outcome (area under the receiver operating characteristic curve (AUC-ROC), 0.76; 95% CI, 0.55-0.89) and a good radiological outcome (AUC-ROC, 0.90; 95% CI, 0.72-0.97), and it was an independent predictor for good radiological outcome (OR: 4.38; 95% CI:1.29-14.82; P<0.01) in multivariate models.

CONCLUSIONS

The CBV ratio is a suitable parameter for evaluating CS quantitatively for patients with AIS that can predict patient response to recanalization.

Computed Tomography-Based Imaging Algorithms for Patient Selection in Acute Ischemic Stroke

Computed tomography remains the most widely used imaging modality for evaluating patients with acute ischemic stroke. Landmark trials have used computed tomography imaging to select patients for intravenous thrombolysis and endovascular treatment. This review summarizes the most important acute ischemic stroke trials, provides an outlook of ongoing studies, and proposes possible image algorithms for patient selection. Although evaluation with anatomic computed tomography imaging techniques is sufficient in early window patients, more advanced imaging techniques should be used beyond 6 hours from symptoms onset to quantify the ischemic core and evaluate for the salvageable penumbra.

Emerging stroke systems of care in Germany

In order to reduce intrahospital times for stroke patients, we have implemented various strategies throughout the last 4 years. Swift restoration of cerebral perfusion is essential for the outcomes of patients with acute ischemic stroke. Endovascular treatment (EVT) has become the standard of care to accomplish this in patients with acute stroke due to large vessel occlusion (LVO). To achieve reperfusion of ischemic brain regions as fast as possible, all in-hospital time delays have to be avoided. Therefore management of patients with acute ischemic stroke was optimized with an interdisciplinary standard operating procedure (SOP). Stroke neurologists, diagnostic as well as interventional neuroradiologists, and anesthesiologists streamlined all necessary processes from patient admission and diagnosis to EVT of eligible patients. In a second step we established a one-stop management of stroke patients, meaning that imaging was acquired with the same angiography suite use for treatment of patients with LVO. In the last section of this chapter we discuss the latest trials on stroke therapy and their implications for our current triage systems and imaging patterns.

Recent Administration of Iodinated Contrast Renders Core Infarct Estimation Inaccurate Using RAPID Software

BACKGROUND AND PURPOSE

Automated CTP software is increasingly used for extended window emergent large-vessel occlusion to quantify core infarct. We aimed to assess whether RAPID software underestimates core infarct in patients with an extended window recently receiving IV iodinated contrast.

MATERIALS AND METHODS

We reviewed a prospective, single-center data base of 271 consecutive patients who underwent CTA ± CTP for acute ischemic stroke from May 2018 through January 2019. Patients with emergent large-vessel occlusion confirmed by CTA in the extended window (>6 hours since last known well) and CTP with RAPID postprocessing were included. Two blinded raters independently assessed CT ASPECTS on NCCT performed at the time of CTP. RAPID software used relative cerebral blood flow of <30% as a surrogate for irreversible core infarct. Patients were dichotomized on the basis of receiving recent IV iodinated contrast (<8 hours before CTP) for a separate imaging study.

RESULTS

The recent IV contrast and contrast-naïve cohorts comprised 23 and 15 patients, respectively. Multivariate linear regression analysis demonstrated that recent IV contrast administration was independently associated with a decrease in the RAPID core infarct estimate (proportional increase = 0.34; 95% CI, 0.12-0.96; P = .04).

CONCLUSIONS

Patients who received IV iodinated contrast in proximity (<8 hours) to CTA/CTP as part of a separate imaging study had a much higher likelihood of core infarct underestimation with RAPID compared with contrast-naïve patients. Over-reliance on RAPID postprocessing for treatment disposition of patients with extended window emergent large-vessel occlusion should be avoided, particularly with recent IV contrast administration.

Predictors of Good Outcomes in Patients with Failed Endovascular Thrombectomy

OBJECTIVE

Endovascular thrombectomy (EVT) fails in approximately 20% of anterior circulation large vessel occlusion (AC-LVO). Nonetheless, the factors that affect clinical outcomes of non-recanalized AC-LVO despite EVT are less studied. The purpose of this study was to identify the factors affecting clinical outcomes in non-recanalized AC-LVO patients despite EVT.

MATERIALS AND METHODS

This was a retrospective analysis of clinical and imaging data from 136 consecutive patients who demonstrated recanalization failure (modified thrombolysis in cerebral ischemia [mTICI], 0-2a) despite EVT for AC-LVO. Data were collected in prospectively maintained registries at 16 stroke centers. Collateral status was categorized into good or poor based on the CT angiogram, and the mTICI was categorized as 0-1 or 2a on the final angiogram. Patients with good (modified Rankin Scale [mRS], 0-2) and poor outcomes (mRS, 3-6) were compared in multivariate analysis to evaluate the factors associated with a good outcome.

RESULTS

Thirty-five patients (25.7%) had good outcomes. The good outcome group was younger (odds ratio [OR], 0.962; 95% confidence interval [CI], 0.932-0.992; p = 0.015), had a lower incidence of hypertension (OR, 0.380; 95% CI, 0.173-0.839; p = 0.017) and distal internal carotid artery involvement (OR, 0.149; 95% CI, 0.043-0.520; p = 0.003), lower initial National Institute of Health Stroke Scale (NIHSS) (OR, 0.789; 95% CI, 0.713-0.873; p < 0.001) and good collateral status (OR, 13.818; 95% CI, 3.971-48.090; p < 0.001). In multivariate analysis, the initial NIHSS (OR, 0.760; 95% CI, 0.638-0.905; p = 0.002), good collateral status (OR, 14.130; 95% CI, 2.264-88.212; p = 0.005) and mTICI 2a recanalization (OR, 5.636; 95% CI, 1.216-26.119; p = 0.027) remained as independent factors with good outcome in non-recanalized patients.

CONCLUSION

Baseline NIHSS score, good collateral status, and mTICI 2a recanalization remained independently associated with clinical outcome in non-recanalized patients. mTICI 2a recanalization would benefit patients with good collaterals in non-recanalized AC-LVO patients despite EVT.

Prediction of mTICI 3 recanalization and clinical outcomes in endovascular thrombectomy for acute ischemic stroke: a retrospective study in the Taiwan registry

PURPOSE

Early recanalization for acute ischemic stroke (AIS) due to large vessel occlusion (LVO) by endovascular thrombectomy (EVT) is strongly related to improved functional outcomes. With data obtained from the Taiwan registry, the factors associated with mTICI 3 recanalization and clinical outcomes in EVT are investigated.

METHODS

From January 2014 to September 2016, 108 patients who underwent EVT for AIS due to LVO in 11 medical centers throughout Taiwan were included. Complete recanalization is defined as achieving modified thrombolysis in cerebral infarction (mTICI) grade 3. Good clinical outcomes are defined by the modified Rankin scale (mRS) 0-2 at 3 months after EVT. Clinical and imaging parameters for predicting mTICI 3 recanalization and good clinical outcomes are analyzed.

RESULTS

Of the 108 patients who received EVT, 54 (50%) patients had mTICI 3 recanalization. Having received aspiration only and the use of IV-tPA are shown to be significant predictors for mTICI 3 recanalization with odds ratios of 2.61 and 2.53 respectively. Forty-six (42.6%) patients experienced good 3-month clinical outcomes (mRS 0-2). Pretreatment collateral statuses, NIHSS scores, time lapses between symptoms to needle, and the occurrence of hemorrhage at 24 h are all significant predictors for good outcomes with odds ratios of 2.88, 0.91, 0.99, and 0.31 respectively.

CONCLUSIONS

Prediction of mTICI 3 recanalization and clinical outcomes offer valuable clinical information for treatment planning in EVT.

Dynamic CTA-Derived Perfusion Maps Predict Final Infarct Volume: The Simple Perfusion Reconstruction Algorithm

BACKGROUND AND PURPOSE

Infarct core volume measurement using CTP (CT perfusion) is a mainstay paradigm for stroke treatment decision-making. Yet, there are several downfalls with cine CTP technology that can be overcome by adopting the simple perfusion reconstruction algorithm (SPIRAL) derived from multiphase CTA. We compare SPIRAL with CTP parameters for the prediction of 24-hour infarction.

MATERIALS AND METHODS

Seventy-two patients had admission NCCT, multiphase CTA, CTP, and 24-hour DWI. All patients had successful/quality reperfusion. Patient-level and cohort-level receiver operator characteristic curves were generated to determine accuracy. A 10-fold cross-validation was performed on the cohort-level data. Infarct core volume was compared for SPIRAL, CTP-time-to-maximum, and final DWI by Bland-Altman analysis.

RESULTS

When we compared the accuracy in patients with early and late reperfusion for cortical GM and WM, there was no significant difference at the patient level (0.83 versus 0.84, respectively), cohort level (0.82 versus 0.81, respectively), or the cross-validation (0.77 versus 0.74, respectively). In the patient-level receiver operating characteristic analysis, the SPIRAL map had a slightly higher, though nonsignificant (P < .05), average receiver operating characteristic area under the curve (cortical GM/WM, r = 0.82; basal ganglia  = 0.79, respectively) than both the CTP-time-to-maximum (cortical GM/WM = 0.82; basal ganglia = 0.78, respectively) and CTP-CBF (cortical GM/WM = 0.74; basal ganglia = 0.78, respectively) parameter maps. The same relationship was observed at the cohort level. The Bland-Altman plot limits of agreement for SPIRAL and time-to-maximum infarct volume were similar compared with 24-hour DWI.

CONCLUSIONS

We have shown that perfusion maps generated from a temporally sampled helical CTA are an accurate surrogate for infarct core.

Plaque characteristics and hemodynamics contribute to neurological impairment in patients with ischemic stroke and transient ischemic attack

OBJECTIVES

We aimed to investigate differential characteristics of plaque in the middle cerebral artery (MCA) and hemodynamics in patients with ischemic stroke and transient ischemic attack (TIA), and to develop a predictive model for the presence of ischemic stroke and neurological impairment.

METHODS

Sixty-seven patients with acute ischemic events in MCA territory who underwent high-resolution vessel wall imaging between September 2016 and August 2018 were reviewed retrospectively. Patients were assigned to either the stroke group or TIA group, according to diffusion-weighted imaging and neurological examination. Plaque characteristics and anterograde score (AnS) were calculated. Tmax > 6.0-s volume was acquired by RApid Processing of perfusIon and Diffusion software. Multivariate logistic regression analysis and multiple linear regression analysis were performed to establish a predictive model for irreversible infarction occurrence and clinical severity.

RESULTS

Forty-five patients were assigned to the stroke group, and 22 were assigned to the TIA group. Plaque length, intraplaque hemorrhage (IPH), enhancement, AnS, and Tmax > 6.0-s volumes were significantly different between the two groups (p < 0.05). IPH and AnS were independent predictors for patients with stroke (p = 0.020 and 0.034, respectively). Tmax > 6.0-s volume, IPH, hypertension, and AnS were associated with high National Institutes of Health Stroke Scale (NIHSS) scores (all p < 0.05, R = 0.725, and adjusted R² = 0.494).

CONCLUSIONS

IPH and AnS are useful in predicting stroke occurrence. Tmax > 6.0-s volume, IPH, hypertension, and AnS are associated with neurological impairment of the patients.

KEY POINTS

• Ischemic stroke and TIA patients have different plaque characteristics and hemodynamics. • Intraplaque hemorrhage and anterograde score have high diagnostic efficiency for ischemic stroke. • The combination of Tmax > 6.0-s volume, intraplaque hemorrhage, hypertension, and anterograde score can predict the National Institutes of Health Stroke Scale scores of patients.

Delayed phase computed tomography angiography ASPECTS predicts clinical outcome and final infarct volume

Background and purpose

Non-contrast computed tomography (NCCT) Alberta Stroke Program Early CT Score (ASPECTS) and assessment of collateral flow with multiphase computed tomography angiography (CTA) have been investigated as predictors of clinical outcome in patients with acute ischemic stroke. This study assessed the value of multiphase CTA ASPECTS in predicting final infarction core and clinical outcome in patients undergoing endovascular treatment of acute ischemic stroke.

Methods

We retrospectively studied consecutive patients who underwent multiphase CTA prior to endovascular treatment of acute stroke due to anterior circulation large artery occlusion. Multiphase CTA and final diffusion-weighted imaging (DWI) scans were evaluated by two independent observers for NCCT ASPECTS, acute phase CTA (CTA-AP) ASPECTS, delayed phase CTA (CTA-DP) ASPECTS, and final DWI ASPECTS. Modified Rankin Scale score ≤2 at 3 months was considered a favorable outcome.

Results

A total of 74 patients were analyzed. We found that CTA-DP ASPECTS (r = 0.82; 95% CI, 0.73–0.91; p < 0.001) correlated with final DWI ASPECTS better than NCCT ASPECTS (r = 0.49; 95% CI, 0.39–0.59) and CTA-AP ASPECTS (r = 0.71; 95% CI, 0.64–0.78). Interobserver agreement was higher for CTA-DP ASPECTS (k = 0.84). Good CTA-DP ASPECTS was an independent predictor of favorable outcome (odds ratio, 8.71; 95% CI, 3.71–17.3; p < 0.001).

Conclusion

CTA-DP ASPECTS is a reliable predictor of final infarction core and neurological outcome.

Cerebral collaterals in acute ischaemia: Implications for acute ischaemic stroke patients receiving reperfusion therapy

The cerebral collaterals play an important role in penumbral tissue sustenance after an acute ischaemic stroke. Recent studies have demonstrated the potential role of collaterals in the selection of acute ischaemic stroke patients eligible for reperfusion therapy. However, the understanding of the significance and evidence around the role of collateral status in predicting outcomes in acute ischaemic stroke patients treated with reperfusion therapy is still unclear. Moreover, the use of pre-treatment collaterals in patient selection and prognosis is relatively underappreciated in clinical settings. A focused review of the literature was performed on the various methods of collateral evaluation and the role of collateral status in acute ischaemic stroke patients receiving reperfusion therapy. We discuss the methods of evaluating pre-treatment collaterals in clinical settings. The patient selection based on collateral status as well as the prognostic and therapeutic value of collaterals in acute ischaemic stroke, in settings of intravenous thrombolysis or endovascular therapy alone, and bridge therapy, are summarized. Recommendations for future research and possible pharmacological intervention strategies aimed at collateral enhancement are also discussed. Collaterals may play an important role in identifying acute ischaemic stroke patients who are likely to benefit from endovascular treatment in an extended time window. Future neuroscientific efforts to better improve our understanding of the role of collaterals in acute ischaemia as well as clinical studies to delineate its role in patient selection and acute stroke prognosis are warranted.

A meta-analysis of collateral status and outcomes of mechanical thrombectomy

OBJECTIVES

To perform a systematic review and meta-analysis to investigate pretreatment collaterals and outcomes of mechanical thrombectomy in patients with acute ischemic stroke of large-vessel occlusion in anterior circulation.

METHODS

We systematically searched Embase, PubMed, and the Cochrane Library from their dates of inception to March 5, 2020, and also manually searched reference lists of relevant articles. Pooled relative risk with 95% confidence interval on the association between good collaterals and functional independence (in terms of mRS 0-2), symptomatic intracranial hemorrhage, mortality, and successful reperfusion were synthesized using a random-effects model.

RESULTS

Thirty-four studies enrolling 5768 patients were included in analysis. Good collaterals were significantly associated with functional independence (RR 1.93, 95%CI 1.64-2.27, P < .0001), successful reperfusion (RR 1.23, 95%CI 1.12-1.35, P < .0001), decreased rate of symptomatic intracranial hemorrhage (RR 0.68, 95%CI 0.47-0.97, P = .032), and mortality (RR 0.37, 95%CI 0.27-0.52, P < .0001). The results were consistent in sensitivity analysis. The associations between good collaterals and reperfusion remained stable after adjusting for publication bias.

CONCLUSIONS

Good pretreatment collaterals were associated with functional independence, successful reperfusion, and decreased rate of sICH and mortality after receiving mechanical thrombectomy in patients with acute ischemic stroke of large-vessel occlusion.

Clinical prognosis of FLAIR hyperintense arteries in ischaemic stroke patients: a systematic review and meta-analysis

OBJECTIVE

We performed a systematic review and meta-analysis to determine the association of fluid-attenuated inversion recovery (FLAIR) hyperintense arteries (FLAIR-HAs) on brain MRI and prognosis after acute ischaemic stroke (AIS).

METHODS

We searched Medline, Embase and Cochrane Central Register of Controlled Trials for studies reporting clinical or imaging outcomes with presence of FLAIR-HAs after AIS. Two researchers independently assessed eligibility of retrieved studies and extracted data, including from the Enhanced Control of Hypertension and Thrombolysis Stroke Study (ENCHANTED). Outcomes were unfavourable functional outcome (primary, modified Rankin scale scores 3-6 or 2-6), death, intermediate clinical and imaging outcomes. We performed subgroup analyses by treatment or types of FLAIR-HAs defined by location (at proximal/distal middle cerebral artery (MCA), within/beyond diffusion-weighted imaging (DWI) lesion) or extent.

RESULTS

We included 36 cohort studies (33 prospectively collected) involving 3577 patients. FLAIR-HAs were not associated with functional outcome overall (pooled risk ratio 0.87, 95% CI 0.71 to 1.06), but were significantly associated with better outcome in those receiving endovascular therapy (0.56, 95% CI 0.41 to 0.75). Contrary to FLAIR-HAs at proximal MCA or within DWI lesions, FLAIR-HAs beyond DWI lesions were associated with better outcome (0.67, 95% CI 0.57 to 0.79). FLAIR-HAs favoured recanalisation (1.21, 95% CI 1.06 to 1.38) with increased risk of intracerebral haemorrhage (2.07, 95% CI 1.37 to 3.13) and early neurological deterioration (1.93, 95% CI 1.30 to 2.85).

CONCLUSIONS

FLAIR-HAs were not associated with functional outcome overall but were associated with outcome after endovascular therapy for AIS. FLAIR-HAs were also associated with early recanalisation or haemorrhagic complications, and early neurologic deterioration.

PROSPERO REGISTRATION NUMBER

CRD42019131168.

Lenticulostriate arteries appearance before thrombectomy predicts good outcome in acute middle cerebral artery occlusion

Background

Endovascular therapy is widely used in acute large vessel occlusion. This study investigated whether imaging of lateral lenticulostriate arteries (LSAs) before thrombectomy would potentially be helpful for predicting prognosis of patients with acute M1 segment of middle cerebral artery occlusion (MCAO).

Methods

59 consecutive patients with acute M1 segment of MCAO treated with mechanical thrombectomy at two comprehensive stroke centers were analyzed. Patients were categorized into LSA+ (appearing of lateral LSAs) and LSA- (sparing of lateral LSAs) group according to preprocedural digital substraction angiography (DSA). Baseline data and clinical outcomes were compared. A good clinical outcome was defined as a modified Rankin Scale score of 0 to 2 at 3 months. The association between clinical and imaging parameters and functional outcome was evaluated with logistic regression analysis.

Results

LSA+ was shown in 36 patients (61%). LSA+ group had a significantly higher proportion of good outcome (72.2% vs. 8.7%, OR 27.3,95% CI 5.38–138.4, P < 0.001), lower risk of symptomatic intracranial haemorrhages (sICH) (8.3% vs. 47.8%,OR 0.10,95% CI 0.02–0.42, P = 0.001) and lower mortality in hospital (5.6% vs. 34.8%, OR 0.11,95% CI 0.02–0.58, P < 0.004) compared with LSA- group. Patients in LSA+ group had lower baseline NIHSS score(P < 0.01) and NIHSS score at 14 days(P < 0.01) and smaller infarct core volume (P = 0.016) on computed tomography perfusion imaging (CTP) compared to the LSA- group. Multivariate logistic regression analysis showed that a small infarct core volume (OR 6.74,95% CI 1.148–39.569, P = 0.035) and LSA+(OR 22.114,95% CI 3.339–146.470, P = 0.001) were associated with a good clinical outcome.

Conclusions

Our data suggest that appearance of lateral LSAs before mechanical thrombectomy would be potentially helpful for predicting favorable prognosis of patients with acute M1 segment of MCAO.

Clinical and Imaging Determinants of Collateral Status in Patients With Acute Ischemic Stroke in MR CLEAN Trial and Registry

Background and Purpose- Collateral circulation status at baseline is associated with functional outcome after ischemic stroke and effect of endovascular treatment. We aimed to identify clinical and imaging determinants that are associated with collateral grade on baseline computed tomography angiography in patients with acute ischemic stroke due to an anterior circulation large vessel occlusion. Methods- Patients included in the MR CLEAN trial (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands; n=500) and MR CLEAN Registry (n=1488) were studied. Collateral status on baseline computed tomography angiography was scored from 0 (absent) to 3 (good). Multivariable ordinal logistic regression analyses were used to test the association of selected determinants with collateral status. Results- In total, 1988 patients were analyzed. Distribution of the collateral status was as follows: absent (7%, n=123), poor (32%, n=596), moderate (39%, n=735), and good (23%, n=422). Associations for a poor collateral status in a multivariable model existed for age (adjusted common odds ratio, 0.92 per 10 years [95% CI, 0.886-0.98]), male (adjusted common odds ratio, 0.64 [95% CI, 0.53-0.76]), blood glucose level (adjusted common odds ratio, 0.97 [95% CI, 0.95-1.00]), and occlusion of the intracranial segment of the internal carotid artery with occlusion of the terminus (adjusted common odds ratio 0.50 [95% CI, 0.41-0.61]). In contrast to previous studies, we did not find an association between cardiovascular risk factors and collateral status. Conclusions- Older age, male sex, high glucose levels, and intracranial internal carotid artery with occlusion of the terminus occlusions are associated with poor computed tomography angiography collateral grades in patients with acute ischemic stroke eligible for endovascular treatment.

Efficacy and safety of nerinetide for the treatment of acute ischaemic stroke (ESCAPE-NA1): a multicentre, double-blind, randomised controlled trial

BACKGROUND

Nerinetide, an eicosapeptide that interferes with post-synaptic density protein 95, is a neuroprotectant that is effective in preclinical stroke models of ischaemia-reperfusion. In this trial, we assessed the efficacy and safety of nerinetide in human ischaemia-reperfusion that occurs with rapid endovascular thrombectomy in patients who had an acute ischaemic stroke.

METHODS

For this multicentre, double-blind, randomised, placebo-controlled study done in 48 acute care hospitals in eight countries, we enrolled patients with acute ischaemic stroke due to large vessel occlusion within a 12 h treatment window. Eligible patients were aged 18 years or older with a disabling ischaemic stroke at the time of randomisation, had been functioning independently in the community before the stroke, had an Alberta Stroke Program Early CT Score (ASPECTS) greater than 4, and vascular imaging showing moderate-to-good collateral filling, as determined by multiphase CT angiography. Patients were randomly assigned (1:1) to receive intravenous nerinetide in a single dose of 2·6 mg/kg, up to a maximum dose of 270 mg, on the basis of estimated or actual weight (if known) or saline placebo by use of a real-time, dynamic, internet-based, stratified randomised minimisation procedure. Patients were stratified by intravenous alteplase treatment and declared endovascular device choice. All trial personnel and patients were masked to sequence and treatment allocation. All patients underwent endovascular thrombectomy and received alteplase in usual care when indicated. The primary outcome was a favourable functional outcome 90 days after randomisation, defined as a modified Rankin Scale (mRS) score of 0-2. Secondary outcomes were measures of neurological disability, functional independence in activities of daily living, excellent functional outcome (mRS 0-1), and mortality. The analysis was done in the intention-to-treat population and adjusted for age, sex, baseline National Institutes of Health Stroke Scale score, ASPECTS, occlusion location, site, alteplase use, and declared first device. The safety population included all patients who received any amount of study drug. This trial is registered with ClinicalTrials.gov, NCT02930018.

FINDINGS

Between March 1, 2017, and Aug 12, 2019, 1105 patients were randomly assigned to receive nerinetide (n=549) or placebo (n=556). 337 (61·4%) of 549 patients with nerinetide and 329 (59·2%) of 556 with placebo achieved an mRS score of 0-2 at 90 days (adjusted risk ratio 1·04, 95% CI 0·96-1·14; p=0·35). Secondary outcomes were similar between groups. We observed evidence of treatment effect modification resulting in inhibition of treatment effect in patients receiving alteplase. Serious adverse events occurred equally between groups.

INTERPRETATION

Nerinetide did not improve the proportion of patients achieving good clinical outcomes after endovascular thrombectomy compared with patients receiving placebo.

FUNDING

Canadian Institutes for Health Research, Alberta Innovates, and NoNO.

Comparison Between Perfusion- and Collateral-Based Triage for Endovascular Thrombectomy in a Late Time Window

Background and Purpose—

Perfusion-based triage has proven to be effective and safe for selecting patients who are likely to benefit from endovascular thrombectomy (EVT) in a late time window. We investigated collateral-based triage for EVT in patients presenting beyond 6 hours, in terms of interrater reliability and efficacy in predicting clinical outcome, in comparison to perfusion-based triage.

Methods—

One hundred and thirty-two patients who underwent both computed tomographic angiography and computed tomography perfusion for anterior circulation large artery occlusion 6 to 24 hours after last seen well were enrolled. Patients were classified into EVT-eligible and EVT-ineligible groups according to perfusion- and collateral-based triages. We evaluated the interrater reliability of collateral-based triage and differences in good outcome rates of patients who received EVT in the EVT-eligible groups based on perfusion- and collateral-based triages.

Results—

Both computed tomographic angiography and computed tomography perfusion were assessable in 93 patients. Seventy-six patients were eligible for EVT according to perfusion-based triage. Among them, EVT was performed in 58, of whom 32 (55.1%) had good outcome. Sixty-nine patients were eligible for EVT based on collateral-based triage. Among them, EVT was performed in 50 patients, of whom 31 (62.0%) had good outcome. Interrater reliability of collateral-based triage was good (generalized κ=0.73 [95% CI, 0.59–0.84]). Agreement on EVT eligibility between perfusion- and collateral-based triages was moderate (κ=0.41 [95% CI, 0.16–0.61]). There was no difference in good outcome rates of patients who underwent EVT in the EVT-eligible groups based on perfusion- and collateral-based triages (55.1% versus 62.0%; P =0.0675).

Conclusions—

Collateral-based triage showed good interrater reliability and comparable efficacy to that of perfusion-based triage in predicting clinical outcome after EVT in patients presenting beyond 6 hours. Collateral-based triage is a reliable approach for selecting patients for EVT in the extended therapeutic time window.

The Association Between Recanalization, Collateral Flow, and Reperfusion in Acute Stroke Patients: A Dynamic Susceptibility Contrast MRI Study

Background: Collateral circulation in ischemic stroke patients plays an important role in infarct evolution und assessing patients' eligibility for endovascular treatment. By means of dynamic susceptibility contrast MRI, we aimed to investigate the effects of reperfusion, recanalization, and collateral flow on clinical and imaging outcomes after stroke. Methods: Retrospective analysis of 184 patients enrolled into the prospective observational 1000Plus study (clinicaltrials.org NCT00715533). Inclusion criteria were vessel occlusion on baseline MR-angiography, imaging within 24 h after stroke onset and follow-up perfusion imaging. Baseline Higashida score using subtracted dynamic MR perfusion source images was used to quantify collateral flow. The influence of these variables, and their interaction with vessel recanalization, on clinical and imaging outcomes was assessed using robust linear regression. Results: Ninety-eight patients (53.3%) showed vessel recanalization. Higashida score (p = 0.002), and recanalization (p = 0.0004) were independently associated with reperfusion. However, we found no evidence that the association between Higashida score and reperfusion relied on recanalization status (p = 0.2). NIHSS on admission (p < 0.0001) and recanalization (p = 0.001) were independently associated with long-term outcome at 3 months, however, Higashida score (p = 0.228) was not. Conclusion: Higashida score and recanalization were independently associated with reperfusion, but the association between recanalization and reperfusion was similar regardless of collateral flow quality. Recanalization was associated with long-term outcome. DSC-based measures of collateral flow were not associated with long-term outcome, possibly due to the complex dynamic nature of collateral recruitment, timing of imaging and the employed post-processing.

Does Sex Modify the Effect of Endovascular Treatment for Ischemic Stroke?

Supplemental Digital Content is available in the text.

Previous studies have reported less favorable outcome and less effect of endovascular treatment (EVT) after ischemic stroke in women than in men. Our aim was to study the influence of sex on outcome and on the effect of EVT for ischemic stroke in recent randomized trials on EVT.

Measurement of collateral perfusion in acute stroke: a vessel-encoded arterial spin labeling study

Collateral perfusion is important for sustaining tissue viability in acute ischemic stroke. Conventional techniques for its visualization are invasive, require contrast agents and demonstrate collateral vessels, rather than measuring perfusion directly. In this study we utilize a non-invasive, non-contrast magnetic resonance imaging (MRI)-based method to directly quantify collateral perfusion in acute stroke patients. Vessel-encoded multi-postlabeling delay arterial spin labeling (ASL) was used to separately quantify the blood flow and blood arrival time from four arteries supplying the brain in patients presenting within 18 hours of stroke onset. Twenty-nine acute ischemic stroke patients were scanned with a median time of onset to first MRI of 3 hours. Collateral perfusion at presentation was associated with tissue fate at 1-week. It sustained tissue prior to reperfusion, but was less effective than direct blood flow at maintaining tissue viability in patients who did not reperfuse. Delay in the blood arrival around the ischemic region was found at presentation and reduced over time but was not consistently associated with collateral perfusion. Vessel-encoded multi-postlabeling delay ASL provides a non-invasive tool for direct measurement of collateral perfusion and delayed blood arrival in acute stroke patients.

Postreperfusion Blood Pressure Variability After Endovascular Thrombectomy Affects Outcomes in Acute Ischemic Stroke Patients With Poor Collateral Circulation

Background and Purpose: We evaluated the effect of 24 h blood pressure variability (BPV) on clinical outcomes in acute ischemic stroke patients with successful recanalization after endovascular recanalization therapy (ERT). Methods: Patients with anterior circulation occlusion were evaluated if they underwent ERT based on multiphase computed tomography angiography and achieved successful recanalization (≥thrombolysis in cerebral ischemia 2b). Collateral degrees were dichotomized based on the pial arterial filling score, with a score of 0-3 defined as a poor collateral status. BPV parameters include mean, standard deviation, coefficient of variation, and variation independent of the mean (VIM) for systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure, and pulse rate (PR). These parameters were measured for 24 h after ERT and were analyzed according to occlusion sites and stroke mechanisms. Associations of BPV parameters with clinical outcomes were investigated with stratification based on the baseline collateral status. Results: BPV was significantly different according to the occlusion sites and stroke mechanisms, and higher BPV was observed in patients with internal carotid artery occlusion or cardioembolic occlusion. After adjustment for confounders, most BPV parameters remained significant to predict functional outcomes at 3 months in patients with poor collateral circulation. However, no significant association was found between BPV parameters and clinical outcomes in patients with good collateral circulation. Conclusion: Postreperfusion BP management by decreasing BPV may have influence on improving clinical outcome in cases of poor collateral circulation among patients achieving successful recanalization after ERT.

Dismantling the ability of CT and MRI to identify the target mismatch profile in patients with anterior circulation large vessel occlusion beyond six hours from symptom onset

PURPOSE

Patients with large vessel occlusion and target mismatch on imaging may be thrombectomy candidates in the extended time window. However, the ability of imaging modalities including non-contrast CT Alberta Stroke Program Early Computed Tomographic Scoring (CT ASPECTS), CT angiography collateral score (CTA-CS), diffusion-weighted MRI ASPECTS (DWI ASPECTS), DWI lesion volume, and DWI volume with clinical deficit (DWI + NIHSS), to identify mismatch is unknown.

METHODS

We defined target mismatch as core infarct (DWI volume) of < 70 mL, mismatch volume (tissue with TMax > 6 s) of ≥ 15 mL, and mismatch ratio of ≥ 1.8. Using experimental dismantling design, ability to identify this profile was determined for each imaging modality independently (phase 1) and then with knowledge from preceding modalities (phase 2). We used a generalized mixed model assuming binary distribution with PROC GLIMMIX/SAS for analysis.

RESULTS

We identified 32 patients with anterior circulation occlusions, presenting > 6 h from symptom onset, with National Institute of Health Stroke Scale of ≥ 6, who had CT and MR before thrombectomy. Sensitivities for identifying target mismatch increased modestly from 88% for NCCT to 91% with the addition of CTA-CS, and up to 100% for all MR-based modalities. Significant gains in specificity were observed from successive tests (29, 19, and 16% increase for DWI ASPECTS, DWI volume, and DWI + NIHSS, respectively).

CONCLUSIONS

The combination of NCCT ASPECTS and CTA-CS has high sensitivity for identifying the target mismatch in the extended time window. However, there are gains in specificity with MRI-based imaging, potentially identifying treatment candidates who may have been excluded based on CT imaging alone.

Impact of single phase CT angiography collateral status on functional outcome over time: results from the MR CLEAN Registry

Background

Collateral status modified the effect of endovascular treatment (EVT) for stroke in several randomized trials. We assessed the association between collaterals and functional outcome in EVT treated patients and investigated if this association is time dependent.

Methods

We included consecutive patients from the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in The Netherlands (MR CLEAN) Registry (March 2014–June 2016) with an anterior circulation large vessel occlusion undergoing EVT. Functional outcome was measured on the modified Rankin Scale (mRS) at 90 days. We investigated the association between collaterals and mRS in the MR CLEAN Registry with ordinal logistic regression and if this association was time dependent with an interaction term. Additionally, we determined modification of EVT effect by collaterals compared with MR CLEAN controls, and also investigated if this was time dependent with multiplicative interaction terms.

Results

1412 patients were analyzed. Functional independence (mRS score of 0–2) was achieved in 13% of patients with grade 0 collaterals, in 27% with grade 1, in 46% with grade 2, and in 53% with grade 3. Collaterals were significantly associated with mRS (adjusted common OR 1.5 (95% CI 1.4 to 1.7)) and significantly modified EVT benefit (P=0.04). None of the effects were time dependent. Better collaterals corresponded to lower mortality (P<0.001), but not to lower rates of symptomatic intracranial hemorrhage (P=0.14).

Conclusion

In routine clinical practice, better collateral status is associated with better functional outcome and greater treatment benefit in EVT treated acute ischemic stroke patients, independent of time to treatment. Within the 6 hour time window, a substantial proportion of patients with absent and poor collaterals can still achieve functional independence.

Clinical application of susceptibility-weighted imaging in the evaluation of leptomeningeal collateralization

The feasibility of using susceptibility-weighted imaging (SWI) in a clinical setting was assessed for quantifying leptomeningeal collateralization.Eighteen patients with stroke and acute infarction underwent diffusion-weighted imaging, SWI, perfusion-weighted imaging, and magnetic resonance angiography within 3 days after symptom onset. Lesions were evaluated by the Alberta Stroke Program Early CT score (ASPECTS), based on mean transit time, SWI, and cerebral blood volume (CBV).For evaluating ischemic penumbra and leptomeningeal collateralization, the SWI-ASPECTS significantly correlated, respectively, with mean transit time and CBV-ASPECTS (Spearman test, r = 0.793 and 0.682; P < .001, both).The SWI may be useful to quantify leptomeningeal collateralization in patients with acute cerebral infarction.

Relative cerebral blood volume is associated with collateral status and infarct growth in stroke patients in SWIFT PRIME

We aimed to evaluate how predefined candidate cerebral perfusion parameters correlate with collateral circulation status and to assess their capacity to predict infarct growth in patients with acute ischemic stroke (AIS) eligible for endovascular therapy. Patients enrolled in the SWIFT PRIME trial with baseline computed tomography perfusion (CTP) scans were included. RAPID software was used to calculate mean relative cerebral blood volume (rCBV) in hypoperfused regions, and hypoperfusion index ratio (HIR). Blind assessments of collaterals were performed using CT angiography in the whole sample and cerebral angiogram in the endovascular group. Reperfusion was assessed on 27-h CTP; infarct volume was assessed on 27-h magnetic resonance imaging/CT scans. Logistic and rank linear regression models were conducted. We included 158 patients. High rCBV ( p = 0.03) and low HIR ( p = 0.03) were associated with good collaterals. A positive association was found between rCBV and better collateral grades on cerebral angiography ( p = 0.01). Baseline and 27-h follow-up CTP were available for 115 patients, of whom 74 (64%) achieved successful reperfusion. Lower rCBV predicted a higher infarct growth in successfully reperfused patients ( p = 0.038) and in the endovascular treatment group ( p = 0.049). Finally, rCBV and HIR may serve as markers of collateral circulation in AIS patients prior to endovascular therapy.

CLINICAL TRIAL REGISTRATION

Unique identifier: NCT0165746.