Stroke Imaging Selection Modality and Endovascular Therapy Outcomes in the Early and Extended Time Windows

Brain imaging prior to thrombectomy in the late window of large vessel occlusion ischemic stroke: a systematic review and meta-analysis

PURPOSE

Optimal imaging modalities to select patients for endovascular thrombectomy (EVT) in the late window of acute ischemic stroke due to large vessel occlusions (AIS-LVO) are not known. We conducted a systematic review comparing outcomes of patients selected by non-contrast computed tomography (NCCT)/CT angiography (CTA) vs. those selected by CT perfusion (CTP) or magnetic resonance imaging (MRI) for EVT in these patients.

METHODS

We searched PUBMED, EMBASE, and the Cochrane Library from January 1, 2000, to July 15, 2023, to identify studies comparing outcomes of patients selected for EVT by NCCT/CTA vs. CTP or MRI in the late time window for AIS-LVO. Primary outcome was independence (mRS 0-2) at 90 days or discharge. Secondary outcomes were symptomatic intracranial hemorrhage (sICH) and mortality. We pooled data across studies based on an inverse variance method.

RESULTS

Six cohort studies with 4208 patients were included. Pooled results showed no significant difference in the rate of independence at 90 days or discharge (RR 0.96, 95% CI 0.88-1.03) and sICH (RR 1.26, 0.85-1.86) between patients selected by NCCT/CTA vs. CTP or MRI for EVT in the late window of AIS-LVO. However, patients selected by NCCT/CTA vs. CTP or MRI for EVT were associated with a higher risk of mortality (RR 1.21, 1.06-1.39).

CONCLUSION

For AIS-LVO in the late window, patients selected by NCCT/CTA compared with those selected by CTP or MRI for EVT might have a comparable rate of functional independence and sICH. Baseline NCCT/CTA may triage AIS-LVO in the late window.

Endovascular thrombectomy for acute ischemic stroke in elderly patients with large ischemic cores

BACKGROUND

Understanding the benefits and risks of endovascular therapy (EVT) is crucial for elderly patients with large ischemic cores, as the combination of advanced age and extensive brain infarction may negatively impact clinical outcomes.

METHODS

The study retrospectively analyzed clinical outcomes for elderly stroke patients (age ≥ 70) with large ischemic cores (Alberta Stroke Program Early CT Score [ASPECTS] < 6 or ischemic cores ≥ 70 ml) in the anterior circulation using data from our prospective database between June 2018 and January 2022. The effectiveness and risks of EVT in those patients were investigated, with the primary outcome being fair outcome (modified Rankin Scale, mRS ≤ 3).

RESULTS

Among 182 elderly patients with large ischemic core volume (120 in the EVT group and 62 in the non-EVT group), 20.9% (38/182, 22.5% in the EVT group vs. 17.7% in the non-EVT group) achieved a fair outcome. Meanwhile, 49.5% (90/182, 45.8% in the EVT group vs. 56.5% in the non-EVT group) of them died at 3 months. The benefits of EVT numerically exceeded non-EVT treatment for those aged ≤  ~ 85 years or with a mismatch volume ≥  ~ 50 ml. However, after adjustment, EVT was associated with an increased risk of symptomatic intracranial hemorrhage (aOR 4.24, 95%CI 1.262-14.247).

CONCLUSIONS

This study highlights the clinical challenges faced by elderly patients with large infarctions, resulting in poor outcomes at 3 months. EVT may still provide some benefits in this population, but it also carries an increased risk of intracranial hemorrhage.

Effect of computed tomography vs. computed tomography perfusion on mechanical thrombectomy outcomes within 6 hours

OBJECTIVES

It is unclear which selection strategy, plain CT vs. CT perfusion (CTP), is more powerful in predicting outcome after mechanical thrombectomy (MT). We aimed to compare the effect of plain CT and CTP in predicting outcome after MT within 6 h.

METHODS

We conducted a prospective analysis of a retrospective cohort from our single-center study, which had occlusion of the internal carotid artery and middle cerebral artery up to the proximal M2 segment and received MT within 6 h. According to the Alberta Stroke Program Early CT Score (ASPECTS), patients were divided into a high-ASPECTS group (≥ 6) and a low ASPECTS group (< 6). Similarly, patients were divided into mismatch and no-mismatch groups according to the DEFUSE3 criteria for CTP. A good outcome was defined as a 90-day modified Rankin Scale (mRS) score of ≤ 3. Univariate and binary logistic regression analyses were used to investigate the association between different imaging modality and 90-day mRS score, and mortalities, respectively.

RESULTS

The high ASPECTS group included 307 patients (89.2%). The mismatch group included 189 (54.9%) patients meeting the DEFUSE3 criterion. Compared to the low ASPECTS group, the high ASPECTS group had a good outcome (odds ratio (OR), 2.285; [95% confidence interval (CI) (1.106, 4.723)], p = 0.026) and lower mortality (OR, 0.350; [95% CI (0.163, 0.752)], p = 0.007). However, there were no significant differences in good outcomes and mortality between the mismatch and no-mismatch groups.

CONCLUSIONS

Compared with plain CT, CTP does not provide additional benefits in the selection of patients suitable for MT within 6 h.

CLINICAL RELEVANCE STATEMENT

CT perfusion is not superior to plain CT for the prediction of clinical outcomes when selecting patients for mechanical thrombectomy in the first 6 h. In that clinical setting, plain CT may be safe in the absence of perfusion data.

KEY POINTS

• The advantage of CT perfusion (CTP) over CT in pre-mechanical thrombectomy (MT) screening has not been proven for patients with a large infarct core. • CTP is not better than plain CT in predicting good outcome following MT within 6 h. • Plain CT is sufficient for selecting patients suitable for MT within 6 h of large artery occlusion.

Perfusion vs non-perfusion computed tomography imaging in the late window of emergent large vessel ischemic stroke: A systematic review and meta-analysis

BACKGROUND

Guidelines recommend the treatment of emergent large vessel ischemic stroke (ELVIS) patients presenting beyond 6 hours of last known well time with endovascular thrombectomy (EVT) based on perfusion computed tomography (CT) neuroimaging. We compared the outcomes (long-term good clinical outcomes, symptomatic intracranial hemorrhage (sICH), and mortality) of ELVIS patients according to the type of CT neuroimaging they underwent.

METHODS

We searched the following databases: Medline, Embase, CENTRAL, and Scopus from January 1, 2015, to June 14, 2023. We included studies of late-presenting ELVIS patients undergoing EVT that had with data for non-perfusion and perfusion CT neuroimaging. We followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Data were pooled using a random effects model.

RESULTS

We found 7 observational cohorts. Non-perfusion versus perfusion CT was not statistically significantly different for both long-term clinical (n = 3,224; RR: 0.96; 95% CI 0.86 to 1.06; I2 = 18%) and sICH (n = 3,724; RR: 1.08 95% CI 0.60 to 1.94; I2 = 76%). Perfusion CT had less mortality (n = 3874; RR: 1.22; 95% CI 1.07 to 1.40; I2 = 0%). The certainty of these findings is very low because of limitations in the risk of bias, indirectness, and imprecision domains of the Grading of Recommendations, Assessment, Development and Evaluations.

CONCLUSION

The use of either non-perfusion or perfusion CT neuroimaging may have little to no effect on long-term clinical outcomes and sICH for late-presenting EVT patients. Perfusion CT neuroimaging may be associated with a reduced the risk of mortality. Evidence uncertainty warrants randomized trial data.

CTA and CTP for Detecting Distal Medium Vessel Occlusions: A Systematic Review and Meta-analysis

BACKGROUND

The optimal imaging method for detecting distal medium vessel occlusions (DMVOs) remains undefined.

PURPOSE

The objective of this study is to compare the diagnostic performance of CTA with CTP in detecting DMVOs.

DATA SOURCES

We searched PubMed, EMBASE, Web of Science Core Collection, and Cochrane Central Register of Controlled Trials up to March 31, 2023 (PROSPERO: CRD42022344006).

STUDY SELECTION

A total of 12 studies reporting accuracy values of CTA and/or CTP were included, comprising 2607 patients with 479 cases (18.3%) of DMVOs.

DATA ANALYSIS

Pooled sensitivity and specificity of both imaging methods were compared using a random-effects model. Subgroup analyses were performed based on the technique used in CTA (multi or single-phase) and the subtype of DMVOs (M2-only vs. M2 and other DMVOs). We applied Quality Assessment of Diagnostic Accuracy (QUADAS-2) tool and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) quality assessment criteria.

DATA SYNTHESIS

CTA demonstrated significantly lower sensitivity compared to CTP in detecting DMVOs [0.74, 95%CI (0.63-0.82) vs. 0.89, 95% CI (0.82-0.93), P < 0.01]. When subgrouped into single-phase and multi-phase CTA, multi-phase CTA exhibited higher sensitivity for DMVO detection than single-phase CTA [0.91, 95%CI (0.85-0.94) vs. 0.64, 95%CI (0.56-0.71), P < .01], while reaching similar levels to CTP. The sensitivity of single-phase CTA substantially decreased when extending from M2 to other non-M2 DMVOs [0.74, 95%CI (0.63-0.83) vs. 0.61, 0.95%CI (0.53-0.68), P = .02].

LIMITATIONS

We identified an overall high risk of bias and low quality of evidence, attributable to the design and reference standards of most studies.

CONCLUSIONS

Our findings highlight a significantly lower sensitivity of single-phase CTA compared to multi-phase CTA and CTP in diagnosing DMVOs.

Simplified stroke imaging selection modality for endovascular thrombectomy in the extended time window: systematic review and meta-analysis

BACKGROUND

The impact of imaging selection modality on clinical outcomes of endovascular thrombectomy (EVT) in the 6-24-hour time window remains undetermined. We compared the clinical outcomes of a simplified stroke imaging selection modality using non-contrast computed tomography (NCCT)±CT angiography (CTA) with using advanced CT perfusion (CTP).

METHODS

PubMed, Embase, Web of Science, and Cochrane Central Register of Controlled Trials were searched from inception to 1 May 2022 to compare NCCT±CTA and CTP for patient selection for EVT in late-presenting stroke with large vessel occlusions (LVO). The primary outcome was the proportion of patients achieving functional independence (modified Rankin Scale score 0-2) within 180 days. The secondary outcomes included mortality within 90 days, successful recanalization, and any intracranial hemorrhage.

RESULTS

A total of 3419 patients in six articles were included in this meta-analysis. There was no significant difference between NCCT±CTA (no-CTP) and CTP in functional independence either in overall or subgroup analysis. However, the mortality in the no-CTP group was higher than in the CTP group. Furthermore, within the DAWN/DEFUSE 3-like subgroup, there were no significant differences in mortality, successful recanalization, and any intracranial hemorrhage between the two groups.

CONCLUSION

There was no significant difference between the simplified NCCT±CTA modality and the advanced CTP modality. The use of NCCT±CTA may represent a reasonable option for selecting patients for EVT in the extended time window, especially in the absence of CTP and acute phase MRI capabilities.

Clinical efficacy and safety of endovascular treatment for patients with wake-up stroke with large vessel occlusion guided by NCCT-ASPECTS

OBJECTIVE

To evaluate the clinical efficacy and safety of 6 to 24 h endovascular therapy (EVT) in patients with wake-up stroke (WUS) with acute large vessel occlusion (LVO) of the anterior circulation guided by noncontrast computed tomography-Alberta stroke program early CT score (NCCT-ASPECTS).

METHODS

Fifty-three patients with WUS with acute LVO of the anterior circulation who were treated at the Sir Run Run Shaw Hospital of Zhejiang Medical College from January 2018 to March 2021 were retrospectively analyzed. The patients were divided into NCCT-ASPECTS or CT perfusion groups. Baseline data, perioperative data, and 90-d prognostic information were compared between the two groups. Multivariable logistic regression analysis was used to determine the independent factors influencing outcomes.

RESULTS

There were no significant differences in the good prognosis, symptomatic intracranial hemorrhage, and mortality rates between the two groups (P > 0.05). Multivariate logistic regression analysis showed that the puncture-recanalization time was an independent factor for good prognosis.

CONCLUSION

Based on NCCT-ASPECTS guidance, EVT in patients with WUS for acute LVO of the anterior circulation within 6 to 24 h may be safe and effective.

ASPECTS-based net water uptake outperforms target mismatch for outcome prediction in patients with acute ischemic stroke and late therapeutic window

OBJECTIVE

To compare the prognostic value of net water uptake (NWU) and target mismatch (TM) on CT perfusion (CTP) in acute ischemic stroke (AIS) patients with late time window.

METHODS

One hundred and nine consecutive AIS patients with anterior-circulation large vessel occlusion presenting within 6-24 h from onset/last seen well were enrolled. Automated Alberta Stroke Program Early CT Score-based NWU (ASPECTS-NWU) was calculated from admission CT. The correlation between ASPECTS-NWU and CTP parameters was assessed. Predictors for favorable outcome (modified Rankin Scale score ≤ 2) at 90 days were assessed using logistic regression analysis. The ability of outcome prediction between ASPECTS-NWU and TM (an ischemic core < 70 mL, a mismatch ratio ≥ 1.8, and an absolute difference ≥ 15 mL) was compared using receiver operating characteristic (ROC) curve.

RESULTS

A higher level of ASPECTS-NWU was associated with a larger ischemic core (r = 0.66, p < 0.001) and a larger hypoperfusion volume (r = 0.38, p < 0.001). ASPECTS-NWU performed better than TM for outcome stratification (area under the curve [AUC], 0.738 vs 0.583, p = 0.004) and was the only independent neuroimaging marker associated with favorable outcomes compared with CTP parameters (odds ratio, 0.73; 95% confidence interval [CI] 0.62-0.87, p < 0.001). An outcome prediction model including ASPECTS-NWU and clinical variables (National Institutes of Health Stroke Scale scores and age) yielded an AUC of 0.828 (95% CI 0.744-0.893; sensitivity 65.4%; specificity 87.7%).

CONCLUSION

ASPECTS-NWU performed better than TM for outcome prediction in AIS patients with late time window and might be an alternative imaging biomarker to CTP for patient selection.

CLINICAL RELEVANCE STATEMENT

Automated Alberta Stroke Program Early CT Score-based net water uptake outperforms target mismatch on CT perfusion for the outcome prediction in patients with acute ischemic stroke and can be an alternative imaging biomarker for patient selection in late therapeutic window.

KEY POINTS

• A higher ASPECTS-based net water uptake was associated with larger ischemic cores and hypoperfusion volumes on CT perfusion. • ASPECTS-based net water uptake outperformed target mismatch for outcome prediction in acute ischemic stroke with extended therapeutic window. • ASPECTS-based net water uptake can be an alternative biomarker to target mismatch for selecting acute ischemic stroke patients with late therapeutic window.

Reperfusion therapy for acute ischemic stroke: where are we in 2023?

Over the last three decades, stroke care has undergone significant transformations mainly driven by the introduction of reperfusion therapy and the organization of systems of care. Patients receiving treatment through a well-structured stroke service have a much higher chance of favorable outcomes, thereby decreasing both disability and mortality. In this article, we reviewed the scientific evidence for stroke reperfusion therapy, including thrombolysis and thrombectomy, and its implementation in the public health system in Brazil.

Endovascular thrombectomy for acute ischaemic stroke with established large infarct: multicentre, open-label, randomised trial

BACKGROUND

Recent evidence suggests a beneficial effect of endovascular thrombectomy in acute ischaemic stroke with large infarct; however, previous trials have relied on multimodal brain imaging, whereas non-contrast CT is mostly used in clinical practice.

METHODS

In a prospective multicentre, open-label, randomised trial, patients with acute ischaemic stroke due to large vessel occlusion in the anterior circulation and a large established infarct indicated by an Alberta Stroke Program Early Computed Tomographic Score (ASPECTS) of 3-5 were randomly assigned using a central, web-based system (using a 1:1 ratio) to receive either endovascular thrombectomy with medical treatment or medical treatment (ie, standard of care) alone up to 12 h from stroke onset. The study was conducted in 40 hospitals in Europe and one site in Canada. The primary outcome was functional outcome across the entire range of the modified Rankin Scale at 90 days, assessed by investigators masked to treatment assignment. The primary analysis was done in the intention-to-treat population. Safety endpoints included mortality and rates of symptomatic intracranial haemorrhage and were analysed in the safety population, which included all patients based on the treatment they received. This trial is registered with ClinicalTrials.gov, NCT03094715.

FINDINGS

From July 17, 2018, to Feb 21, 2023, 253 patients were randomly assigned, with 125 patients assigned to endovascular thrombectomy and 128 to medical treatment alone. The trial was stopped early for efficacy after the first pre-planned interim analysis. At 90 days, endovascular thrombectomy was associated with a shift in the distribution of scores on the modified Rankin Scale towards better outcome (adjusted common OR 2·58 [95% CI 1·60-4·15]; p=0·0001) and with lower mortality (hazard ratio 0·67 [95% CI 0·46-0·98]; p=0·038). Symptomatic intracranial haemorrhage occurred in seven (6%) patients with thrombectomy and in six (5%) with medical treatment alone.

INTERPRETATION

Endovascular thrombectomy was associated with improved functional outcome and lower mortality in patients with acute ischaemic stroke from large vessel occlusion with established large infarct in a setting using non-contrast CT as the predominant imaging modality for patient selection.

FUNDING

EU Horizon 2020.

Noncontrast versus perfusion CT to select endovascular therapy in an extended time window: Systematic review/meta-analysis

BACKGROUND AND PURPOSE

The effect of noncontrast CT (NCCT) on the eligibility for endovascular therapy (EVT) in an extended time window remains to be elucidated. We sought to assess the efficacy and safety of NCCT in comparison with CT perfusion (CTP) in selecting patients with acute ischemic stroke (AIS) for EVT 6-24 hours after onset.

METHODS

PubMed, Embase, and Cochrane libraries were searched from inception to August 31, 2022, to identify all studies reporting 90-day outcomes of EVT in patients with AIS in an extended time window. A meta-analysis was performed for the pooled risk ratio (RR) with 95% confidence interval (CI) using a random-effects model. The primary outcome used to assess efficacy was good functional independence, defined as a modified Rankin Scale score of 0-2 at 90 days. Secondary outcomes included successful reperfusion, symptomatic intracranial hemorrhage (sICH), and mortality at 90 days.

RESULTS

We included four nonrandomized studies with a total of 2685 patients. The outcomes of good functional independence at 90 days (RR = 0.98; 95% CI: 0.88-1.07; I2  = 0%; p = .62), successful reperfusion (RR = 0.98; 95% CI: 0.93-1.03; I2  = 50.5%; p = .11), sICH (RR = 1.11; 95% CI: 0.55-2.21; I2  = 49.4%; p = .12), or mortality at 90 days (RR = 1.18; 95% CI: 0.99-1.40; I2  = 0%; p = .42) did not differ significantly between the two groups.

CONCLUSIONS

These findings suggest that NCCT is as effective as CTP in selecting patients for EVT in an extended time window.

Angiographic collateral venous phase: a novel landmark for leptomeningeal collaterals evaluation in acute ischemic stroke

BACKGROUND

Although recanalization rates constantly increase (>80%), a favorable clinical outcome is achieved in only 45-55% of patients undergoing mechanical thrombectomy (MT) for anterior circulation stroke. Collateral circulation seems to play a major role in determining this discrepancy. The aim of the study was to investigate a novel angiographic landmark assessing the collateral venous phase (CVP) compared with the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) score, based on the arterial collateral assessment.

METHODS

Two hundred patients with anterior circulation stroke treated by MT between 2016 and 2021 were included. The ASITN/SIR score and the presence of CVP were blindly evaluated by expert neuroradiologists. Three subanalyses were performed comparing patients with good versus poor collaterals, CVP presence versus absence, and a composite analysis including both ASITN/SIR and CVP grading results.

RESULTS

Good collateral circulation (ASITN >2) was observed in 113 patients (56.5%) whereas CVP was present in 90 patients (45%) and mostly in patients with good collaterals. Favorable clinical and neuroradiological outcomes were more likely observed in patients with both good collaterals and the presence of CVP than in those with good collaterals and absence of CVP (modified Rankin Scale score 0-2: 77.3% vs 7.9%, p<0.0001; mortality: 9.3% vs 26.3%, p=0.02; 24-hour Alberta Stroke Program Early CT Score: 8 vs 6, p<0.0001), while ASITN/SIR score alone was not significantly associated with clinical outcomes.

CONCLUSIONS

The presence of CVP improves the angiographic assessment of collateral circulation. CVP could be proposed as a new imaging landmark to better understand the functionality of collaterals.

Comparison of clinical outcomes in patients with acute ischemic stroke who underwent endovascular treatment using different perfusion modalities: a real-world multicenter study

Background

Advanced perfusion modalities are increasingly popular for various diseases. However, few studies have focused on contrasting perfusion patterns.

Objective

This study aimed to compare the time efficiency and clinical outcomes of patients with acute ischemic stroke (AIS) who underwent endovascular treatment (EVT) before one-stop arterial spin labeling (ASL) and computed tomography perfusion (CTP) protocols.

Methods

This study retrospectively included 326 patients with AIS who had accepted EVT within 24 h of onset from four comprehensive stroke centers between October 2017 and September 2022. After 1:1 matching of the propensity scores, 202 patients were separated into two groups: the ASL group (n = 101) and the CTP group (n = 101).

Results

Functional independence at 90 days (modified Rankin Scale [mRS] 0-2; p = 0.574), onset-to-puncture time (p = 0.231), door-to-puncture time (p = 0.136), and door-to-perfusion time (p = 0.646) were not significantly different between the two groups. The proportion of EVT complications (31.7% in the ASL group vs. 14.9% in the CTP group, p = 0.005) and symptomatic intracranial hemorrhage (sICH) at 24 h (23.8% in the ASL group vs. 9.9% in the CTP group, p = 0.008) in the CTP group were lower than the ASL group. The ischemic core volume was a common predictor of favorable outcomes in both ASL (p < 0.001) and CTP (p < 0.001) groups.

Conclusion

There were no significant differences in time efficiency and efficacy outcomes between the two groups of patients receiving one-stop ASL and CTP. The proportion of sICH at 24 h and EVT complications of patients in the CTP group was lower than the ASL group. The ischemic core volume was an independent predictor for favorable outcomes.

Aspiration thrombectomy with the Penumbra System for patients with stroke and late onset to treatment: a subset analysis of the COMPLETE registry

Background

The purpose of this study was to report the safety and performance of aspiration thrombectomy with the Penumbra System for patients with acute ischemic stroke (AIS) due to anterior circulation large vessel occlusion (LVO) and late onset to treatment.

Methods

This is a retrospective subset analysis of a global prospective multicenter registry (COMPLETE) that enrolled adults with AIS due to LVO and a pre-stroke modified Rankin Scale score (mRS) of 0 or 1 who were treated first-line with aspiration thrombectomy either alone (A Direct Aspiration First Pass Technique [ADAPT]) or in combination with the 3D Revascularization Device (ADAPT + 3D). This subset analysis included all patients in the registry who had anterior circulation LVO, an Alberta Stroke Program Early CT Score of at least 6, and late onset to treatment (>6 h from stroke onset to puncture).

Results

Of the 650 patients in the COMPLETE registry, 167 were included in this subset analysis. The rate of successful revascularization (modified thrombolysis in cerebral infarction score 2b-3 achieved) at the end of the procedure was 83.2%, the rate of good functional outcome (mRS 0-2) at 90 days was 55.4%, and the all-cause mortality rate at 90 days was 14.4%. No device-related serious adverse events (SAEs) occurred. Procedure-related SAEs occurred in 9 patients (5.4%) within 24 h and in 12 patients (7.2%) overall. The rate of successful revascularization was higher for patients treated first-line with ADAPT (88.0%) than for patients treated first-line with ADAPT + 3D (75.0%; p = 0.035); no significant difference was observed between the ADAPT and ADAPT + 3D groups for any other primary or secondary outcome.

Conclusion

For patients with AIS due to anterior circulation LVO and with late onset to treatment, aspiration thrombectomy with the Penumbra System appears to be safe and effective. The rates of good functional outcome and all-cause mortality from this study compared favorably with those rates from the medical management arms of the DAWN and DEFUSE-3 studies.

Clinical trial registration

https://www.clinicaltrials.gov, NCT03464565.

Alberta Stroke Program Early CT Score and collateral status predict target mismatch in large vessel occlusion with delayed time windows

BACKGROUND

The Alberta Stroke Program Early CT Score (ASPECTS) and collateral score (CS) are two readily available imaging metrics for the evaluation of acute ischemic stroke (AIS) with large vessel occlusion (LVO).

OBJECTIVE

To investigate the predictive value of the ASPECTS combined with CS in detecting patients with CT perfusion (CTP) target mismatch in delayed time windows.

METHODS

One hundred and sixty-four patients with LVO-AIS were included. ASPECTS was assessed on non-contrast CT (NCCT). CS was evaluated on single-phase CT angiography (sCTA). Target mismatch was defined as a CTP core volume ≤70 mL, mismatch ratio ≥1.8, and absolute mismatch volume ≥15 mL. Spearman correlation analysis and receiver operating characteristic curve analyses were performed.

RESULTS

The median NCCT ASPECTS of the 164 patients was 8 (IQR 6-9), median sCTA-CS was 2 (IQR 1-2), and median CTP core volume was 8 mL (IQR 0-29.5). There was a strong correlation between NCCT ASPECTS and CTP core volume (rs=-0.756, p<0.0001) and a moderate correlation between the sCTA-CS and CTP core volume (rs=-0.450, p<0.0001). Integrating NCCT ASPECTS and sCTA-CS provided a higher area under the curve (AUC) for predicting target mismatch (AUC=0.882; sensitivity, 89.1%; specificity, 77.8%; p<0.001).

CONCLUSIONS

NCCT ASPECTS had a strong correlation with CTP core volumes in patients with LVO-AIS in delayed time windows. Combining NCCT ASPECTS with sCTA-CS resulted in a more accurate prediction of target mismatch. If a CTP scan is not available, NCCT ASPECTS combined with sCTA-CS may guide clinicians in making treatment decisions.

Stroke imaging modality for endovascular therapy in the extended window: systematic review and meta-analysis

BACKGROUND

In anterior circulation large vessel occlusion (LVO) in the extended time window, the guidelines recommend advanced imaging (ADVI) to select patients for endovascular therapy (EVT). However, questions remain regarding its availability and applicability in the real world. It is unclear whether an approach to the extended window EVT that does not use ADVI would be equivalent.

METHODS

In April 2022, a literature search was performed to identified randomized controlled trials (RCT) and observational studies describing 90-day outcomes. We performed a meta-analysis of the proportion of aggregate using a random effect to estimate rates of functional independence, defined as modified Rankin Scale (mRS) score ≤2 at 90 days, mean mRS, mortality and symptomatic intracranial hemorrhage (sICH) stratified by imaging modality.

RESULTS

Four RCTs and 28 observational studies were included. The pooled proportion of functional independence among patients selected by ADVI was 44% (95% CI 39% to 48%; I2=80%) and 48% (95% CI 41% to 55%; I2=75%) with non-contrast CT/CT angiography (NCCT/CTA) (p=0.36). Mean mRS with ADVI was 2.88 (95% CI 2.36 to 3.41; I2=0.0%) and 2.79 (95% CI 2.31 to 3.27; I2=0.0%) with NCCT (p=0.79). Mortality in patients selected by ADVI was 13% (95% CI 10% to 17%; I2=81%) and 16% (95% CI 12% to 22%; I2=69%) with NCCT (p=0.29). sICH with ADVI was 4% (95% CI 3% to 7%; I2=73%) and 6% with NCCT/CTA (95% CI 4% to 8%; I2=6%, p=0.27).

CONCLUSIONS

Our study suggests that, in anterior circulation LVO, the rates of functional independence may be similar when patients are selected using ADVI or NCCT for EVT in the extended time window. A simplified triage protocol does not seem to increase mortality or sICH. PROTOCOL REGISTRATION NUMBER: (PROSPERO ID: CRD42021236092).

Thrombectomy with and without computed tomography perfusion imaging for large-vessel occlusion stroke in the extended time window: a meta-analysis of randomized clinical trials

Objective

In recent years, several studies have used computed tomography perfusion (CTP) to assess whether mechanical thrombectomy can be performed in patients with large-vessel occlusion (LVO) stroke in an extended time window. However, it has the disadvantage of being time-consuming and expensive. This study aimed to compare the impact of the CTP group with the non-CTP group [non-contrast CT (NCCT) ± CT angiography (CTA)] on the prognosis of this patient population.

Methods

A search of PubMed, EMBASE, and the Cochrane Library databases was conducted to collect randomized controlled trials (RCTs) comparing the two strategies. Outcome indicators and factors influencing prognosis were summarized by standardized mean differences, ratios, and relative risks with 95% confidence intervals using a random-effects model.

Results

A total of two RCTs were included in the combined analysis. There were no significant differences in the main outcome indicators (modified Rankin Scale score at 90 days, successful postoperative reperfusion rate) or the incidence of adverse events (90-day mortality and symptomatic intracranial hemorrhage) between the NCCT ± CTA and CTP groups. The time from the last puncture appeared to be significantly shorter in the NCCT ± CTA group than in the CTP group (SMD: -0.14; 95% CI: -0.24, -0.04). Among them, age (OR: 0.96; 95% CI: 0.94, 0.98), ASPECTS (OR: 1.18; 95% CI: 1.12, 1.24), NIHSS score (OR: 0.90; 95% CI: 0.89, 0.91), and diabetes (OR: 0.69; 95% CI: 0.54, 0.88) were associated with a 90-day independent functional outcome.

Conclusion

These findings suggest that the choice of NCCT ± CTA (without CTP) for the assessment of mechanical thrombectomy within 6-24 h after LVO in the anterior circulation is not significantly different from CTP; instead, the choice of NCCT ± CTA significantly reduces the time from onset to arterial puncture.

CT Perfusion vs Noncontrast CT for Late Window Stroke Thrombectomy: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

Patients with acute ischemic stroke (AIS) treated with endovascular thrombectomy (EVT) in the late window (6-24 hours) can be evaluated with CT perfusion (CTP) or with noncontrast CT (NCCT) only. Whether outcomes differ depending on the type of imaging selection is unknown. We conducted a systematic review and meta-analysis comparing outcomes between CTP and NCCT for EVT selection in the late therapeutic window.

METHODS

This study is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses 2020 guidelines. A systematic literature review of the English language literature was conducted using Web of Science, Embase, Scopus, and PubMed databases. Studies focusing on late-window AIS undergoing EVT imaged through CTP and NCCT were included. Data were pooled using a random-effects model. The primary outcome of interest was rate of functional independence, defined as modified Rankin scale 0-2. The secondary outcomes of interest included rates of successful reperfusion, defined as thrombolysis in cerebral infarction 2b-3, mortality, and symptomatic intracranial hemorrhage (sICH).

RESULTS

Five studies with 3,384 patients were included in our analysis. There were comparable rates of functional independence (odds ratio [OR] 1.03, 95% CI 0.87-1.22; p = 0.71) and sICH (OR 1.09, 95% CI 0.58-2.04; p = 0.80) between the 2 groups. Patients imaged with CTP had higher rates of successful reperfusion (OR 1.31, 95% CI 1.05-1.64; p = 0.015) and lower rates of mortality (OR 0.79, 95% CI 0.65-0.96; p = 0.017).

DISCUSSION

Although recovery of functional independence after late-window EVT was not more common in patients selected by CTP when compared with patients selected by NCCT only, patients selected by CTP had lower mortality.

Advanced Imaging for Acute Stroke Treatment Selection: CT, CTA, CT Perfusion, and MR Imaging

There is constant evolution in the diagnosis and treatment of acute ischemic stroke due to advances in treatments, imaging, and outreach. Two major revolutions were the advent of intravenous thrombolysis in the 1990s and endovascular thrombectomy in 2010s. Neuroimaging approaches have also evolved with key goals-detect hemorrhage, augment thrombolysis treatment selection, detect arterial occlusion, estimate infarct core, estimate viable penumbra, and augment thrombectomy treatment selection. The ideal approach to diagnosis and treatment may differ depending on the system of care and available resources. Future directions include expanding indications for these treatments, including a shift from time-based to tissue-based selection.

Imaging of Central Nervous System Ischemia

OBJECTIVE

This article describes imaging modalities used in the evaluation of patients presenting with symptoms of acute ischemic stroke.

LATEST DEVELOPMENTS

The year 2015 marked the beginning of a new era in acute stroke care with the widespread adoption of mechanical thrombectomy. Subsequent randomized controlled trials in 2017 and 2018 brought the stroke community even further into this new territory with the expansion of the eligibility window for thrombectomy using imaging-based patient selection, which led to an increase in the use of perfusion imaging. Now, after several years of routine use, the debate is ongoing as to when this additional imaging is truly required and when it results in unnecessary delays in time-sensitive stroke care. At this time, more than ever, a robust understanding of neuroimaging techniques, applications, and interpretation is essential for the practicing neurologist.

ESSENTIAL POINTS

CT-based imaging is the first step in most centers for the evaluation of patients presenting with symptoms of acute stroke because of its wide availability, speed, and safety. Noncontrast head CT alone is sufficient for IV thrombolysis decision making. CT angiography is very sensitive for the detection of large-vessel occlusion and can be used reliably to make this determination. Advanced imaging including multiphase CT angiography, CT perfusion, MRI, and MR perfusion can provide additional information useful for therapeutic decision making in specific clinical scenarios. In all cases, it is essential that neuroimaging be performed and interpreted rapidly to allow for timely reperfusion therapy.

Head CT deep learning model is highly accurate for early infarct estimation

Non-contrast head CT (NCCT) is extremely insensitive for early (< 3-6 h) acute infarct identification. We developed a deep learning model that detects and delineates suspected early acute infarcts on NCCT, using diffusion MRI as ground truth (3566 NCCT/MRI training patient pairs). The model substantially outperformed 3 expert neuroradiologists on a test set of 150 CT scans of patients who were potential candidates for thrombectomy (60 stroke-negative, 90 stroke-positive middle cerebral artery territory only infarcts), with sensitivity 96% (specificity 72%) for the model versus 61-66% (specificity 90-92%) for the experts; model infarct volume estimates also strongly correlated with those of diffusion MRI (r² > 0.98). When this 150 CT test set was expanded to include a total of 364 CT scans with a more heterogeneous distribution of infarct locations (94 stroke-negative, 270 stroke-positive mixed territory infarcts), model sensitivity was 97%, specificity 99%, for detection of infarcts larger than the 70 mL volume threshold used for patient selection in several major randomized controlled trials of thrombectomy treatment.

Automated Estimation of Quantitative Lesion Water Uptake as a Prognostic Biomarker for Patients with Ischemic Stroke and Large-Vessel Occlusion

BACKGROUND AND PURPOSE

Net water uptake is qualified as an imaging marker of brain edema. We aimed to investigate the ability of net water uptake to predict 90-day functional outcome in patients with acute ischemic stroke and large-vessel occlusion.

MATERIALS AND METHODS

A total of 295 consecutive patients were retrospectively enrolled. Automated ASPECTS-net water uptake was calculated on the admission CT. The relationship between ASPECTS-net water uptake and 90-day neurologic outcome was assessed. The independent predictors of favorable outcome (mRS score ≤2) were assessed using multivariate logistic regression analysis and receiver operating characteristic curves and stratified by the ASPECTS.

RESULTS

Favorable 90-day outcomes were observed in 156 (52.9%) patients. ASPECTS-net water uptake (OR, 0.79; 95% CI, 0.70-0.90), NIHSS scores (OR, 0.91; 95% CI, 0.87-0.96), age (OR, 0.96; 95% CI, 0.94-0.99), and vessel recanalization (OR, 7.78; 95% CI, 3.96-15.29) were independently associated with favorable outcomes at 90 days (all, P < .01). A lower ASPECTS-net water uptake independently predicted a good prognosis, even in the subgroup of patients with low ASPECTS (≤5) (P < .05). An outcome-prediction model based on these variables yielded an area under the receiver operating characteristic curve of 0.856 (95% CI, 0.814-0.899; sensitivity, 76.3%; specificity, 81.3%).

CONCLUSIONS

ASPECTS-net water uptake could independently predict 90-day neurologic outcomes in patients with acute ischemic stroke and large-vessel occlusion. Integrating ASPECTS-net water uptake with clinical models could improve the efficiency of outcome stratification.

Symmetric collateral pattern on CTA predicts favorable outcomes after endovascular thrombectomy for large vessel occlusion stroke

Endovascular thrombectomy (EVT) has revolutionized large vessel occlusion (LVO) stroke management, but often requires advanced imaging. The collateral pattern on CT angiograms may be an alternative because a symmetric collateral pattern correlates with a slowly growing, small ischemic core. We tested the hypothesis that such patients will have favorable outcomes after EVT. Consecutive patients (n = 74) with anterior LVOs who underwent EVT were retrospectively analyzed. Inclusion criteria were available CTA and 90-day modified Rankin Scale (mRS). CTA collateral patterns were symmetric in 36%, malignant in 24%, or other in 39%. Median NIHSS was 11 for symmetric, 18 for malignant, and 19 for other (p = 0.02). Ninety-day mRS ≤2, indicating independent living, was achieved in 67% of symmetric, 17% of malignant, and 38% of other patterns (p = 0.003). A symmetric collateral pattern was a significant determinant of 90-day mRS ≤2 (aOR = 6.62, 95%CI = 2.24,19.53; p = 0.001) in a multivariable model that included age, NIHSS, baseline mRS, thrombolysis, LVO location, and successful reperfusion. We conclude that a symmetric collateral pattern predicts favorable outcomes after EVT for LVO stroke. Because the pattern also marks slow ischemic core growth, patients with symmetric collaterals may be suitable for transfer for thrombectomy. A malignant collateral pattern is associated with poor clinical outcomes.

Diagnostic accuracy of CT angiography and CT perfusion imaging for detecting distal medium vessel occlusions: Protocol for a systematic review and meta-analysis

BACKGROUND

Distal medium vessel occlusions (DMVOs) represent 25-40% of all acute ischemic strokes (AIS). DMVO clinical syndromes are heterogenous, but as eloquent brain regions are frequently involved, they are often disabling. Since current intravenous fibrinolytic therapies may fail to recanalize up to two-thirds of DMVOs, endovascular treatment is progressively being considered in this setting. Nevertheless, the optimal imaging method for diagnosis remains to be defined. Stroke centers that use computed tomography as a routine stroke imaging approach rely on either isolated computed tomography angiography (CTA) or combined perfusion (CTP) studies. Despite a simplified non-CTP-dependent approach seeming reasonable for large vessel occlusion AIS diagnosis, CTP may still hold advantages for DMVOs workup. Therefore, this systematic review aims to compare the diagnostic performance of CTA and CTP in detecting DMVOs.

METHODS

We will perform a systematic search in PubMed, EMBASE, Web of Science Core Collection, and Cochrane Central Register of Controlled Trials. In addition, grey literature and ClinicalTrials.gov will be scanned. We will include any type of study that presents data on the diagnostic accuracy of CTA and/or CTP for detecting DMVOs. Two authors will independently review retrieved studies, and any discrepancies will be resolved by consensus or with a third reviewer. Reviewers will extract the data and assess the risk of bias in the selected studies. Data will be combined in a quantitative meta-analysis following the guidelines provided by the Cochrane Handbook for Systematic Reviews of Interventions. We will assess cumulative evidence using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

DISCUSSION

This will be the first systematic review and meta-analysis that compares two different imaging approaches for detecting DMVOs. This study may help to define optimal acute ischemic stroke imaging work-up.

TRIAL REGISTRATION

PROSPERO registration: CRD42022344006.

Does MRI add value in selecting patients for thrombectomy beyond the 6 h window? A matched-control analysis

Background

Controversy exists regarding the need of advanced imaging for patient selection in the extended window.

Aims

To analyze the effect of initial imaging modalities on clinical outcomes of patients underwent MT in the extended window.

Methods

This was a retrospective analysis of a prospective registry, the Endovascular Treatment Key Technique and Emergency Workflow Improvement of Acute Ischemic Stroke (ANGEL-ACT) registry which was conducted at 111 hospitals between November 2017 and March 2019 in China. Primary study cohort and Guideline like cohort were identified, in each cohort, two imaging modalities for patient selection in 6 to 24 h window were defined: (1) NCCT ± CTA, (2) MRI. Guideline-like cohort were further screened based on key features of the DAWN and DEFUSE 3 trials. The primary outcome was 90 day mRS. The safety outcomes were sICH, any ICH and 90-day mortality.

Results

After adjusting for covariates, there were no significant differences in 90 day mRS or any safety outcomes between two imaging modalities groups in both cohorts. All outcome measures of mixed-effects logistic regression model were consistent with propensity score matching model.

Conclusion

Our results indicate that patients presented with anterior large vessel occlusion in the extended time window can potentially benefit from MT even in the absence of MRI selection. This conclusion needs to be verified by the prospective randomized clinical trials.

Effect of Intravenous Tirofiban vs Placebo Before Endovascular Thrombectomy on Functional Outcomes in Large Vessel Occlusion Stroke: The RESCUE BT Randomized Clinical Trial

IMPORTANCE

Tirofiban is a highly selective nonpeptide antagonist of glycoprotein IIb/IIIa receptor, which reversibly inhibits platelet aggregation. It remains uncertain whether intravenous tirofiban is effective to improve functional outcomes for patients with large vessel occlusion ischemic stroke undergoing endovascular thrombectomy.

OBJECTIVE

To assess the efficacy and adverse events of intravenous tirofiban before endovascular thrombectomy for acute ischemic stroke secondary to large vessel occlusion.

DESIGN, SETTING, AND PARTICIPANTS

This investigator-initiated, randomized, double-blind, placebo-controlled trial was implemented at 55 hospitals in China, enrolling 948 patients with stroke and proximal intracranial large vessel occlusion presenting within 24 hours of time last known well. Recruitment took place between October 10, 2018, and October 31, 2021, with final follow-up on January 15, 2022.

INTERVENTIONS

Participants received intravenous tirofiban (n = 463) or placebo (n = 485) prior to endovascular thrombectomy.

MAIN OUTCOMES AND MEASURES

The primary outcome was disability level at 90 days as measured by overall distribution of the modified Rankin Scale scores from 0 (no symptoms) to 6 (death). The primary safety outcome was the incidence of symptomatic intracranial hemorrhage within 48 hours.

RESULTS

Among 948 patients randomized (mean age, 67 years; 391 [41.2%] women), 948 (100%) completed the trial. The median (IQR) 90-day modified Rankin Scale score in the tirofiban group vs placebo group was 3 (1-4) vs 3 (1-4). The adjusted common odds ratio for a lower level of disability with tirofiban vs placebo was 1.08 (95% CI, 0.86-1.36). Incidence of symptomatic intracranial hemorrhage was 9.7% in the tirofiban group vs 6.4% in the placebo group (difference, 3.3% [95% CI, -0.2% to 6.8%]).

CONCLUSIONS AND RELEVANCE

Among patients with large vessel occlusion acute ischemic stroke undergoing endovascular thrombectomy, treatment with intravenous tirofiban, compared with placebo, before endovascular therapy resulted in no significant difference in disability severity at 90 days. The findings do not support use of intravenous tirofiban before endovascular thrombectomy for acute ischemic stroke.

TRIAL REGISTRATION

Chinese Clinical Trial Registry Identifier: ChiCTR-IOR-17014167.

Perfusion Imaging for Endovascular Thrombectomy in Acute Ischemic Stroke Is Associated With Improved Functional Outcomes in the Early and Late Time Windows

The impact on clinical outcomes of patient selection using perfusion imaging for endovascular thrombectomy (EVT) in patients with acute ischemic stroke presenting beyond 6 hours from onset remains undetermined in routine clinical practice.

Stroke imaging prior to thrombectomy in the late window: results from a pooled multicentre analysis

BACKGROUND AND PURPOSE

Collateral assessment using CT angiography is a promising modality for selecting patients for endovascular thrombectomy (EVT) in the late window (6-24 hours). The outcome of these patients compared with those selected using perfusion imaging is not clear.

METHODS

We pooled data from seven trials and registries of EVT-treated patients in the late-time window. Patients were classified according to the baseline imaging into collateral imaging alone (collateral cohort) and perfusion plus collateral imaging (perfusion cohort). The primary outcome was the proportion of patients achieving independent 90-day functional outcome (modified Rankin Scale 'mRS' 0-2). We used the propensity score-weighting method to balance important predictors between the cohorts.

RESULTS

In 608 patients, the median onset/last-known-well to emergency arrival time was 8.8 hours and 53.2% had wake-up strokes. Both cohorts had collateral imaging and 379 (62.3%) had perfusion imaging. Independent functional outcome was achieved in 43.1% overall: 168/379 patients (45.5%) in the perfusion cohort versus 94/214 (43.9%) in the collateral cohort (p=0.71). A logistic regression model adjusting for inverse-probability-weighting showed no difference in 90-day mRS score of 0-2 among the perfusion versus collateral cohorts (adjusted OR 1.05, 95% CI 0.69 to 1.59, p=0.83) or in a favourable shift in 90-day mRS (common adjusted OR 1.01, 95% CI 0.69 to 1.47, p=0.97).

CONCLUSION

This pooled analysis of late window EVT showed comparable functional outcomes in patients selected for EVT using collateral imaging alone compared with patients selected using perfusion and collateral imaging.

PROSPERO REGISTRATION NUMBER

CRD42020222003.

Acute stroke imaging selection for mechanical thrombectomy in the extended time window: is it time to go back to basics? A review of current evidence

Treatment with endovascular therapy in the extended time window for acute ischaemic stroke with large vessel occlusion involves stringent selection criteria based on the two landmark studies DAWN and DEFUSE3. Current protocols typically include the requirement of advanced perfusion imaging which may exclude a substantial proportion of patients from receiving a potentially effective therapy. Efforts to offer endovascular reperfusion therapies to all appropriate candidates may be facilitated by the use of simplified imaging selection paradigms with widely available basic imaging techniques, such as non-contrast CT and CT angiography. Currently available evidence from our literature review suggests that patients meeting simplified imaging selection criteria may benefit as much as those patients selected using advanced imaging techniques (CT perfusion or MRI) from endovascular therapy in the extended time window. A comprehensive understanding of the role of imaging in patient selection is critical to optimising access to endovascular therapy in the extended time window and improving outcomes in acute stroke. This article provides an overview on current developments and future directions in this emerging area.

Clinical protocol of the ischemic stroke patients treatment

Today in Ukraine there is no single standardized protocol for the treatment of patients in the acute period of ischemic stroke using modern methods of diagnosis and treatment, which include thrombolytic therapy and endovascular treatment. This protocol was created and implemented in Scientific-practical Center of endovascular neuroradiology, NAMS of Ukraine and is based on the latest recommendations of AHA/ASA and ESO, as well as registers of patients with ischemic stroke. The main purpose of this publication is the creation and implementation of «instructions» for the diagnosis and selection of objective tactics for treating patients in the acute period of ischemic stroke.

Noncontrast Computed Tomography vs Computed Tomography Perfusion or Magnetic Resonance Imaging Selection in Late Presentation of Stroke With Large-Vessel Occlusion

Question

In patients with proximal anterior circulation occlusion stroke presenting in the extended window, are rates of favorable outcomes at 90 days comparable in the patients selected for thrombectomy with noncontrast computed tomography vs patients selected with computed tomography perfusion or magnetic resonance imaging?

Findings

In a multicenter cohort of 1604 patients in the extended window with large-vessel occlusion, patients selected by noncontrast computed tomography had comparable clinical and safety outcomes with patients selected by computed tomography perfusion or magnetic resonance imaging.

Meaning

These findings suggest noncontrast computed tomography alone may be used as an alternative to advanced imaging in selecting patients with late-presenting large-vessel occlusion for mechanical thrombectomy.

Importance

Advanced imaging for patient selection in mechanical thrombectomy is not widely available.

Objective

To compare the clinical outcomes of patients selected for mechanical thrombectomy by noncontrast computed tomography (CT) vs those selected by computed tomography perfusion (CTP) or magnetic resonance imaging (MRI) in the extended time window.

Design, Setting, and Participants

This multinational cohort study included consecutive patients with proximal anterior circulation occlusion stroke presenting within 6 to 24 hours of time last seen well from January 2014 to December 2020. This study was conducted at 15 sites across 5 countries in Europe and North America. The duration of follow-up was 90 days from stroke onset.

Exposures

Computed tomography with Alberta Stroke Program Early CT Score, CTP, or MRI.

Main Outcomes and Measures

The primary end point was the distribution of modified Rankin Scale (mRS) scores at 90 days (ordinal shift). Secondary outcomes included the rates of 90-day functional independence (mRS scores of 0-2), symptomatic intracranial hemorrhage, and 90-day mortality.

Results

Of 2304 patients screened for eligibility, 1604 patients were included, with a median (IQR) age of 70 (59-80) years; 848 (52.9%) were women. A total of 534 patients were selected to undergo mechanical thrombectomy by CT, 752 by CTP, and 318 by MRI. After adjustment of confounders, there was no difference in 90-day ordinal mRS shift between patients selected by CT vs CTP (adjusted odds ratio [aOR], 0.95 [95% CI, 0.77-1.17]; P = .64) or CT vs MRI (aOR, 0.95 [95% CI, 0.8-1.13]; P = .55). The rates of 90-day functional independence (mRS scores 0-2 vs 3-6) were similar between patients selected by CT vs CTP (aOR, 0.90 [95% CI, 0.7-1.16]; P = .42) but lower in patients selected by MRI than CT (aOR, 0.79 [95% CI, 0.64-0.98]; P = .03). Successful reperfusion was more common in the CT and CTP groups compared with the MRI group (474 [88.9%] and 670 [89.5%] vs 250 [78.9%]; P < .001). No significant differences in symptomatic intracranial hemorrhage (CT, 42 [8.1%]; CTP, 43 [5.8%]; MRI, 15 [4.7%]; P = .11) or 90-day mortality (CT, 125 [23.4%]; CTP, 159 [21.1%]; MRI, 62 [19.5%]; P = .38) were observed.

Conclusions and Relevance

In patients undergoing proximal anterior circulation mechanical thrombectomy in the extended time window, there were no significant differences in the clinical outcomes of patients selected with noncontrast CT compared with those selected with CTP or MRI. These findings have the potential to widen the indication for treating patients in the extended window using a simpler and more widespread noncontrast CT–only paradigm.

Symmetric CTA Collaterals Identify Patients with Slow-progressing Stroke Likely to Benefit from Late Thrombectomy

Background Understanding ischemic core growth rate (IGR) is key in identifying patients with slow-progressing large vessel occlusion (LVO) stroke who may benefit from delayed endovascular thrombectomy (EVT). Purpose To evaluate whether symmetric collateral pattern at CT angiography (CTA) can help to identify patients with low IGR and small 24-hour diffusion-weighted MRI ischemic core volume in patients with LVO not treated with reperfusion therapies. Materials and Methods In this secondary analysis of clinical trial data from before EVT became standard of care from January 2007 to June 2009, patients with anterior proximal LVO not treated with reperfusion therapies were evaluated. All patients underwent admission CTA and at least three MRI examinations at four time points over 48 hours. Arterial phase CTA collaterals at presentation were categorized as symmetric, malignant, or other. Diffusion-weighted MRI ischemic core volume and IGR at multiple time points were determined. The IGR at presentation was defined as follows: (ischemic core volume in cubic centimeters)/(time since stroke symptom onset in hours). Multivariable analyses and receiver operator characteristic analyses were used. Results This study evaluated 31 patients (median age, 71 years; interquartile range, 61-81 years; 19 men) with median National Institutes of Health Stroke Scale (NIHSS) score of 13. Collaterals were symmetric (45%; 14 of 31), malignant (13%; four of 31), or other (42%; 13 of 31). Median ischemic core volume was different between collateral patterns at all time points. Presentation was as follows: symmetric, 16 cm³; other, 69 cm³; and malignant, 104 cm³ (P < .001). At 24 hours, median ischemic core volumes were as follows: symmetric, 28 cm³; other, 156 cm³; and malignant, 176 cm³ (P < .001). Median IGR was also different, and most pronounced at presentation: symmetric, 4 cm³ per hour; other, 17 cm³ per hour; and malignant, 20 cm³ per hour (P < .001). After multivariable adjustment, independent determinants of higher presentation IGR included only higher NIHSS (parameter estimate [β = 0.20; 95% CI: 0.05, 0.36; P = .008) and worse collaterals (β = -2.90; 95% CI: -4.31, -1.50; P < .001). The only independent determinant of 24-hour IGR was worse collaterals (β = -2.03; 95% CI: -3.28, -0.78; P = .001). Symmetric collaterals had sensitivity of 87% (13 of 15) and specificity of 94% (15 of 16) for 24-hour ischemic core volume less than 50 cm³ (area under the receiver operating characteristic curve, 0.92; 95% CI: 0.81, 1.00; P < .001). Conclusion In patients with large vessel occlusion not treated with reperfusion therapies, symmetric collateral pattern at CT angiography was common and highly specific for low ischemic core growth rate and small 24-hour ischemic core volume as assessed at diffusion-weighted MRI. After further outcome studies, collateral status at presentation may prove useful in triage for endovascular thrombectomy, especially when MRI and CT perfusion are unavailable. Clinical trial registration no. NCT00414726. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Messina in this issue.

Novel selection paradigms for endovascular stroke treatment in the extended time window

BACKGROUND AND PURPOSE

The optimal selection methodology for stroke thrombectomy beyond 6 hours remains to be established.

METHODS

Review of a prospectively collected database of thrombectomy patients with anterior circulation strokes, adequate CT perfusion (CTP) maps, National Institute of Health Stroke Scale (NIHSS)≥10 and presenting beyond 6 hours from January 2014 to October 2018. Patients were categorised according to five selection paradigms: DAWN clinical-core mismatch (DAWN-CCM): between age-adjusted NIHSS and CTP core, DEFUSE 3 perfusion imaging mismatch (DEFUSE-3-PIM): between CTP-derived perfusion defect (Tmax >6 s lesion) and ischaemic core volumes and three non-contrast CT Alberta Stroke Program Early CT Score (ASPECTS)-based criteria: age-adjusted clinical-ASPECTS mismatch (aCAM): between age-adjusted NIHSS and ASPECTS, eloquence-adjusted clinical ASPECTS mismatch (eCAM): ASPECTS 6-10 and non-involvement of the right M6 and left M4 areas and standard clinical ASPECTS mismatch (sCAM): ASPECTS 6-10.

RESULTS

310 patients underwent analysis. DEFUSE-3-PIM had the highest proportion of qualifying patients followed by sCAM, eCAM, aCAM and DAWN-CCM (93.5%, 92.6%, 90.6%, 90% and 84.5%, respectively). Patients meeting aCAM, eCAM, sCAM and DAWN-CCM criteria had higher rates of 90-day good outcome compared with their non-qualifying counterparts(43.2% vs 12%,p=0.002; 42.4% vs 17.4%, p=0.02; 42.4% vs 11.2%, p=0.009; and 43.7% vs 20.5%, p=0.007, respectively). There was no difference between patients meeting DEFUSE-3-PIM criteria versus not(40.8% vs 31.3%,p=0.45). In multivariate analysis, all selection modalities except for DEFUSE-3-PIM were independently associated with 90-day good outcome.

CONCLUSIONS

ASPECTS-based selection paradigms for late presenting and wake-up strokes ET have comparable proportions of qualifying patients and similar 90-day functional outcomes as DAWN-CCM and DEFUSE-3-PIM. They also might lead to better outcome discrimination. These could represent a potential alternative for centres where access to advanced imaging is limited.

Outcomes of Mechanical Thrombectomy in the Early (<6-hour) and Extended (≥6-hour) Time Window Based Solely on Noncontrast CT and CT Angiography: A Propensity Score-Matched Cohort Study

BACKGROUND AND PURPOSE

Current stroke care recommendations for patient selection for mechanical thrombectomy in the extended time window demand advanced imaging to determine the stroke core volume and hypoperfusion mismatch, which may not be available at every center. We aimed to determine outcomes in patients selected for mechanical thrombectomy solely on the basis of noncontrast CT and CTA in the early (<6-hour) and extended (≥6-hour) time windows.

MATERIALS AND METHODS

Consecutive mechanical thrombectomies performed for acute large-vessel occlusion ischemic (ICA, M1, M2) stroke between February 2016 and August 2020 were retrospectively reviewed. Eligibility was based solely on demographics and noncontrast CT (ASPECTS) and CTA, due to the limited availability of perfusion imaging during the study period. Propensity score matching was performed to compare outcomes between time windows.

RESULTS

Of 417 mechanical thrombectomies performed, 337 met the inclusion criteria, resulting in 205 (60.8%) and 132 (39.2%) patients in the 0- to 6- and 6- to 24-hour time windows, respectively. The ASPECTS was higher in the early time window (9; interquartile range = 8-10) than the extended time window (9; interquartile range = 7-10; P = .005). Propensity score matching yielded 112 well-matched pairs. Equal rates of TICI 2b/3 revascularization and symptomatic intracranial hemorrhage were observed. A favorable functional outcome (mRS 0-2) at 90 days was numerically more frequent in the early window (45.5% versus 33.9%, P = .091). Mortality was numerically more frequent in the early window (25.9% versus 17.0%, P = .096).

CONCLUSIONS

Patients selected for mechanical thrombectomy in the extended time window solely on the basis of noncontrast CT and CTA still achieved decent rates of favorable 90-day functional outcomes, not statistically different from patients in the early time window.

Late Thrombectomy in Clinical Practice : Retrospective Application of DAWN/DEFUSE3 Criteria within the German Stroke Registry

BACKGROUND AND PURPOSE

To provide real-world data on outcome and procedural factors of late thrombectomy patients.

METHODS

We retrospectively analyzed patients from the multicenter German Stroke Registry. The primary endpoint was clinical outcome on the modified Rankin scale (mRS) at 3 months. Trial-eligible patients and the subgroups were compared to the ineligible group. Secondary analyses included multivariate logistic regression to identify predictors of good outcome (mRS ≤ 2).

RESULTS

Of 1917 patients who underwent thrombectomy, 208 (11%) were treated within a time window ≥ 6-24 h and met the baseline trial criteria. Of these, 27 patients (13%) were eligible for DAWN and 39 (19%) for DEFUSE3 and 156 patients were not eligible for DAWN or DEFUSE3 (75%), mainly because there was no perfusion imaging (62%; n = 129). Good outcome was not significantly higher in trial-ineligible (27%) than in trial-eligible (20%) patients (p = 0.343). Patients with large trial-ineligible CT perfusion imaging (CTP) lesions had significantly more hemorrhagic complications (33%) as well as unfavorable outcomes.

CONCLUSION

In clinical practice, the high number of patients with a good clinical outcome after endovascular therapy ≥ 6-24 h as in DAWN/DEFUSE3 could not be achieved. Similar outcomes are seen in patients selected for EVT ≥ 6 h based on factors other than CTP. Patients triaged without CTP showed trends for shorter arrival to reperfusion times and higher rates of independence.

[Imaging-based patient selection for mechanical thrombectomy based on time since symptom onset]

BACKGROUND

In ischemic stroke due to large vessel occlusion (LVO), the indications for patient selection for endovascular mechanical thrombectomy (MT) are based on findings from brain imaging. Several imaging protocols from computed tomography (CT) or magnetic resonance imaging (MRI) are available to guide treatment decisions.

OBJECTIVE

To recommend the optimal choice of imaging modalities and protocols for MT with respect to time windows from symptom onset.

MATERIAL AND METHODS

Evaluation of the results of large randomized placebo-controlled trials regarding imaging-based patient selection in MT categorized by time intervals since symptom onset. We discuss methodological aspects, advantages and caveats of individual stroke imaging protocols. Summary of recommendations for the practice.

RESULTS AND CONCLUSION

In MT trials CT was mostly used for patient selection. Plain CT combined with CT angiography or additional perfusion imaging is the preferred option. In early time windows CT with CTA is adequate (≤ 6 h for MT, ≤ 4.5 h in cases of accompanying thrombolysis according to exclusion criteria). In later or unknown time windows perfusion imaging is needed for patient selection. Patients presenting with unknown time windows should be examined by MRI as a first-line choice in mild to moderate deficits, in cases of severe deficits CT imaging with perfusion imaging.

Clinical effectiveness of endovascular stroke treatment in the early and extended time windows

BACKGROUND

The clinical efficacy of mechanical thrombectomy has been unequivocally demonstrated in multiple randomized clinical trials. However, these studies were performed in carefully selected centers and utilized strict inclusion criteria.

AIM

We aimed to assess the clinical effectiveness of mechanical thrombectomy in a prospective registry.

METHODS

A total of 2008 patients from 76 sites across 12 countries were enrolled in a prospective open-label mechanical thrombectomy registry. Patients were categorized into the corresponding cohorts of the SWIFT-Prime, DAWN, and DEFUSE 3 trials according to the basic demographic and clinical criteria without considering specific parenchymal imaging findings. Baseline and outcome variables were compared across the corresponding groups.

RESULTS

As compared to the treated patients in the actual trials, registry-derived patients tended to be younger and had lower baseline ASPECTS. In addition, time to treatment was earlier and the use of intravenous tissue plasminogen activator (IV-tPA) and general anesthesia were higher in DAWN- and DEFUSE-3 registry derived patients versus their corresponding trials. Reperfusion rates were higher in the registry patients. The rates of 90-day good outcome (mRS0-2) in registry-derived patients were comparable to those of the patients treated in the corresponding randomized clinical trials (SWIFT-Prime, 64.5% vs. 60.2%; DAWN, 50.4% vs. 48.6%; Beyond-DAWN: 52.4% vs. 48.6%; DEFUSE 3, 52% vs. 44.6%, respectively; all P > 0.05). Registry-derived patients had significant less disability than the corresponding randomized clinical trial controls (ordinal modified Rankin Scale (mRS) shift odds ratio (OR), P < 0.05 for all).

CONCLUSION

Our study provides favorable generalizability data for the safety and efficacy of thrombectomy in the "real-world" setting and supports that patients may be safely treated outside the constraints of randomized clinical trials.

Endovascular treatment in anterior circulation stroke beyond 6.5 hours after onset or time last seen well: results from the MR CLEAN Registry

Background

Randomised controlled trials with perfusion selection have shown benefit of endovascular treatment (EVT) for ischaemic stroke between 6 and 24 hours after symptom onset or time last seen well. However, outcomes after EVT in these late window patients without perfusion imaging are largely unknown. We assessed their characteristics and outcomes in routine clinical practice.

Methods

The Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands Registry, a prospective, multicentre study in the Netherlands, included patients with an anterior circulation occlusion who underwent EVT between 2014 and 2017. CT perfusion was no standard imaging modality. We used adjusted ordinal logistic regression analysis to compare patients treated within versus beyond 6.5 hours after propensity score matching on age, prestroke modified Rankin Scale (mRS), National Institutes of Health Stroke Scale, Alberta Stroke Programme Early CT Score (ASPECTS), collateral status, location of occlusion and treatment with intravenous thrombolysis. Outcomes included 3-month mRS score, functional independence (defined as mRS 0–2), and death.

Results

Of 3264 patients who underwent EVT, 106 (3.2%) were treated beyond 6.5 hours (median 8.5, IQR 6.9–10.6), of whom 93 (87.7%) had unknown time of stroke onset. CT perfusion was not performed in 87/106 (80.2%) late window patients. Late window patients were younger (mean 67 vs 70 years, p<0.04) and had slightly lower ASPECTS (median 8 vs 9, p<0.01), but better collateral status (collateral score 2–3: 68.3% vs 57.7%, p=0.03). No differences were observed in proportions of functional independence (43.3% vs 40.5%, p=0.57) or death (24.0% vs 28.9%, p=0.28). After matching, outcomes remained similar (adjusted common OR for 1 point improvement in mRS 1.04, 95% CI 0.56 to 1.93).

Conclusions

Without the use of CT perfusion selection criteria, EVT in the 6.5–24-hour time window was not associated with poorer outcome in selected patients with favourable clinical and CT/CT angiography characteristics. randomised controlled trials with lenient inclusion criteria are needed to identify more patients who can benefit from EVT in the late window.