Advanced modality imaging evaluation in acute ischemic stroke may lead to delayed endovascular reperfusion therapy without improvement in clinical outcomes

Noncontrast CT Selected Thrombectomy vs Medical Management for Late-Window Anterior Large Vessel Occlusion

BACKGROUND AND OBJECTIVES

There is uncertainty whether patients with large vessel occlusion (LVO) presenting in the late 6-hour to 24-hour time window can be selected for endovascular therapy (EVT) by noncontrast CT (NCCT) and CT angiography (CTA) for LVO detection. We evaluated the clinical outcomes of patients selected for EVT by NCCT compared with those medically managed in the extended time window.

METHODS

This multinational cohort study was conducted at 66 sites across 10 countries. Consecutive patients with proximal anterior LVO stroke selected for EVT by NCCT or medically managed and presenting within 6-24 hours of time last seen well (TSLW) from January 2014 to May 2022 were included. The primary end point was the 90-day ordinal shift in the modified Rankin Scale (mRS) score. Inverse probability treatment weighting (IPTW) and multivariable methods were used.

RESULTS

Of 5,098 patients screened, 839 patients were included, with a median (interquartile range) age of 75 (64-83) years; 455 (54.2%) were women. There were 616 patients selected to undergo EVT by NCCT (73.4%) and 223 (26.6%) who were medically managed. In IPTW analyses, there was a more favorable 90-day ordinal mRS shift in patients selected by NCCT to EVT vs those who were medically managed (odds ratio [OR] 1.99, 95% CI 1.53-2.59; p < 0.001). There were higher rates of 90-day functional independence (mRS 0-2) in the EVT group (40.1% vs 18.4%, OR 3.31, 95% CI 2.11-5.20; p < 0.001). sICH was nonsignificantly higher in the EVT group (8.5% vs 1.4%, OR 3.77, 95% CI 0.72-19.7, p = 0.12). Mortality at 90 days was lower in the EVT vs MM group (23.9% vs 32.3%, OR 0.61, 95% CI 0.45-0.83, p = 0.002).

DISCUSSION

In patients with proximal anterior LVO in the extended time window, there was a lower rate of disability and mortality in patients selected with NCCT and CTA to EVT compared with those who were medically managed. These findings support the use of NCCT as a simpler and more inclusive approach to patient selection in the extended window.

TRIAL REGISTRATION INFORMATION

This study was registered at ClinicalTrials.gov under NCT04096248.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for patients with proximal anterior circulation occlusion presenting with ischemic stroke from 6 to 24 hours, compared with medical management, those undergoing thrombectomy based on NCCT have reduced disability and mortality at 90 days.

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.

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.

Specialist Perspectives on the Imaging Selection of Large Vessel Occlusion in the Late Window

BACKGROUND

The proper imaging modality for use in the selection of patients for endovascular thrombectomy (EVT) presenting in the late window remains controversial, despite current guidelines advocating the use of advanced imaging in this population. We sought to understand if clinicians with different specialty training differ in their approach to patient selection for EVT in the late time window.

METHODS

We conducted an international survey of stroke and neurointerventional clinicians between January and May 2022 with questions focusing on imaging and treatment decisions of large vessel occlusion (LVO) patients presenting in the late window. Interventional neurologists, interventional neuroradiologists, and endovascular neurosurgeons were defined as interventionists whereas all other specialties were defined as non-interventionists. The non-interventionist group was defined by all other specialties of the respondents: stroke neurologist, neuroradiologist, emergency medicine physician, trainee (fellows and residents) and others.

RESULTS

Of 3000 invited to participate, 1506 (1027 non-interventionists, 478 interventionists, 1 declined to specify) physicians completed the study. Interventionist respondents were more likely to proceed directly to EVT (39.5% vs. 19.5%; p < 0.0001) compared to non-interventionist respondents in patients with favorable ASPECTS (Alberta Stroke Program Early CT Score). Despite no difference in access to advanced imaging, interventionists were more likely to prefer CT/CTA alone (34.8% vs. 21.0%) and less likely to prefer CT/CTA/CTP (39.1% vs. 52.4%) for patient selection (p < 0.0001). When faced with uncertainty, non-interventionists were more likely to follow clinical guidelines (45.1% vs. 30.2%) while interventionists were more likely to follow their assessment of evidence (38.7% vs. 27.0%) (p < 0.0001).

CONCLUSION

Interventionists were less likely to use advanced imaging techniques in selecting LVO patients presenting in the late window and more likely to base their decisions on their assessment of evidence rather than published guidelines. These results reflect gaps between interventionists and non-interventionists reliance on clinical guidelines, the limits of available evidence, and clinician belief in the utility of advanced imaging.

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.

Neuroimaging of Acute Ischemic Stroke: Multimodal Imaging Approach for Acute Endovascular Therapy

Advances in acute ischemic stroke (AIS) treatment have been contingent on innovations in neuroimaging. Neuroimaging plays a pivotal role in the diagnosis and prognosis of ischemic stroke and large vessel occlusion, enabling triage decisions in the emergent care of the stroke patient. Current imaging protocols for acute stroke are dependent on the available resources and clinicians' preferences and experiences. In addition, differential application of neuroimaging in medical decision-making, and the rapidly growing evidence to support varying paradigms have outpaced guideline-based recommendations for selecting patients to receive intravenous or endovascular treatment. In this review, we aimed to discuss the various imaging modalities and approaches used in the diagnosis and treatment of AIS.

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.

Mechanical Thrombectomy in the Late Presentation of Anterior Circulation Large Vessel Occlusion Stroke: A Guideline From the Society of Vascular and Interventional Neurology Guidelines and Practice Standards Committee

Background and Purpose

Recent clinical trials investigating endovascular therapy (EVT) in the extended time window have opened new treatment paradigms for late-presenting patients with large vessel occlusion (LVO) stroke. The aim of this guideline is to provide up to date recommendations for the diagnosis, selection, and medical or endovascular treatment of patients with LVO presenting in the extended time window.

Methods

The Society of Vascular & Interventional Neurology (SVIN) Guidelines and Practice Clinical Standards (GAPS) committee assembled a writing group and recruited interdisciplinary experts to review and evaluate the current literature. Recommendations were assigned by the writing group using the SVIN-GAPS Class of Recommendation/Level of Evidence algorithm and SVIN GAPS guideline format. The final guideline was approved by all members of the writing group, the GAPS committee, and the SVIN board of directors.

Results

Literature review yielded three high quality randomized trials and several observational studies that have been extracted to derive the enclosed summary recommendations. In patients with LVO presenting in the 6-to-24-hour window, and with clinical imaging mismatch as defined by the DAWN and DEFUSE 3 studies, EVT is recommended. Non contrast CT can be used to evaluate infarct size as sole imaging modality for patient selection, particularly when access to CT perfusion or MRI is limited, or if their performance would incur substantial delay to treatment. In addition, several clinical questions were reviewed based on the available evidence and consensus grading.

Conclusion

These guidelines provide practical recommendations based on recent evidence on the diagnosis, selection, and treatment of patients with LVO stroke presenting in the extended time window.

Comparison of time consumption and success rate between CT angiography- and CT perfusion- based imaging assessment strategy for the patients with acute ischemic stroke

BACKGROUND

Our study aimed to compare the time consumption and success rate between CTA- and CTP- based assessment strategy, and to clarify the risk factors associated with the CTP scan failure.

METHODS

Clinical and radiological data of 437 consecutive AIS patients who underwent multiphase CTA or CTP for pre-treatment evaluation were retrospectively enrolled (CTA group, n = 302; CTP group, n = 135). Time consumption and success rate of CTA- and CTP- based assessment strategy were compared using Mann-Whitney U test and Chi-Squared Test. Univariate analysis and receiver operating curve analysis were used to clarify the risk factors, and their performance in predicting the CTP scan failure.

RESULTS

Time consumption of CTP scan and reconstruction was significantly longer than that of CTA [775 s vs 263.5 s, P < 0.001]. CTP scan showed significantly higher failure rate than CTA (11% vs 1%, P < 0.001). Severe motion was the most common cause of CTP failure (n = 12, 80%). Baseline National Institute of Health Stroke Scale (NIHSS) score in CTP failure group was significantly higher than that in CTP success group [17 vs 13, P = 0.007]. Baseline NIHSS score of 11 was the optimal threshold value to predict CTP failure with an area under the curve of 0.715, a sensitivity of 86.7%, and a specificity of 45.0%.

CONCLUSIONS

CTP- based strategy showed longer time consumption and higher failure rate than CTA- based strategy. High baseline NIHSS score was significantly associated with CTP scan failure in AIS patients.

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.

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.

Workflow Times and Outcome of Endovascular Therapy in Stroke Patients with Initial MRI or CT

INTRODUCTION

Treatment of patients with acute large vessel occlusion (LVO) stroke is highly time dependent. MRI and CT are both used as primary neuroimaging modalities in these patients, which may be associated with differences in workflow times of endovascular therapy (ET), thus potentially affecting clinical outcome. We here aimed to compare workflow times and clinical outcome in a large cohort of patients initially examined by MRI or CT.

METHODS

We analyzed patients who underwent ET between 2015 and 2019 and were enrolled into the prospective multicenter German Stroke Registry-Endovascular Therapy (GSR-ET). Patients who had an MRI prior to ET were compared to patients with a pretreatment CT regarding baseline data, in-hospital workflow times, and clinical outcome.

RESULTS

Three hundred seventy out of 4,638 patients were examined with an initial MRI (8.0%). Compared to patients with an initial CT, MRI patients had a longer median time from hospital admission to imaging acquisition (23 vs. 14 min). All consecutive workflow times did not significantly differ between both groups after adjustment for confounders. Moreover, the clinical outcome did not differ between MRI and CT patients after adjustment for confounders.

CONCLUSION

In LVO stroke patients undergoing ET, pretreatment imaging with MRI instead of CT leads to a delay of imaging acquisition after hospital admission without having a measurable impact on consecutive workflow steps and clinical outcome.

Direct angiographic intervention for acute ischemic stroke with large vessel occlusion

Background:Rapid and effective revascularization is the cornerstone of acute ischemic stroke treatment. Endovascular thrombectomy reperfusion has dramatically changed patients' outcomes with large vessel occlusions. Results of randomized controlled trials have shown that the benefit of this treatment is highly time-sensitive. The purpose of this review is to introduce a new approach to acute stroke treatment - direct angiographic intervention for selected patients. Methods & Results:We examined the issues related to the current guideline-based practice, emphasizing whether the benefit of using advanced multimodal imaging is worth the potential resultant disability generated by delayed reperfusion times. The published evidence supporting this novel concept was reviewed, its safety and feasibility discussed, and appropriate predictive tools for patient selection explored.Conclusion:This new approach may provide benefits for appropriately selected patients. Further prospective trials are needed to clarify the risk-versus-benefit of this approach.Abbreviations and Acronyms: AHA: American Heart AssociationAIS: acute ischemic strokeASA: American Stroke AssociationASPECTS: Alberta Stroke Program Early Computed Tomography ScoreCT: computed tomographyCTA: computed tomography angiographyCTP: computed tomography perfusionDMVO: distal, medium vessel occlusionDSA: digital subtraction angiographyED: Emergency DepartmentEVT: endovascular thrombectomyFD: flat detectorIA: intra-arterialIV: intravenousICH: intracerebral hemorrhageMR: magnetic resonanceMRA: magnetic resonance angiographyMSU: mobile stroke unitNIHSS: National Institutes of Health Stroke ScaleNCCT: non-contrast computed tomographyPLVO: proximal, large vessel occlusionPPV: positive predictive valuePWI: magnetic resonance perfusion-weighted imaging.

Clinically Approximated Hypoperfused Tissue in Large Vessel Occlusion Stroke

[Figure: see text].

Noncontrast Computed Tomography e-Stroke Infarct Volume Is Similar to RAPID Computed Tomography Perfusion in Estimating Postreperfusion Infarct Volumes

BACKGROUND AND PURPOSE

The e-Stroke Suite software (Brainomix, Oxford, United Kingdom) is a tool designed for the automated quantification of The Alberta Stroke Program Early CT Score and ischemic core volumes on noncontrast computed tomography (NCCT). We sought to compare the prediction of postreperfusion infarct volumes and the clinical outcomes across NCCT e-Stroke software versus RAPID (IschemaView, Menlo Park, CA) computed tomography perfusion measurements.

METHODS

All consecutive patients with anterior circulation large vessel occlusion stroke presenting at a tertiary care center between September 2010 and November 2018 who had available baseline infarct volumes on both NCCT e-Stroke Suite software and RAPID CTP as well as final infarct volume (FIV) measurements and achieved complete reperfusion (modified Thrombolysis in Cerebral Infarction scale 2c-3) post-thrombectomy were included. The associations between estimated baseline ischemic core volumes and FIV as well as 90-day functional outcomes were assessed.

RESULTS

Four hundred seventy-nine patients met inclusion criteria. Median age was 64 years (55-75), median e-Stroke and computed tomography perfusion ischemic core volumes were 38.4 (21.8-58) and 5 (0-17.7) mL, respectively, whereas median FIV was 22.2 (9.1-56.2) mL. The correlation between e-Stroke and CTP ischemic core volumes was moderate (R=0.44; P<0.001). Similarly, moderate correlations were observed between e-Stroke software ischemic core and FIV (R=0.52; P<0.001) and CTP core and FIV (R=0.43; P<0.001). Subgroup analysis showed that e-Stroke software and CTP performance was similar in the early and late (>6 hours) treatment windows. Multivariate analysis showed that both e-Stroke software NCCT baseline ischemic core volume (adjusted odds ratio, 0.98 [95% CI, 0.97-0.99]) and RAPID CTP ischemic core volume (adjusted odds ratio, 0.98 [95% CI, 0.97-0.99]) were independently and comparably associated with good outcome (modified Rankin Scale score of 0-2) at 90 days.

CONCLUSIONS

NCCT e-Stroke Suite software performed similarly to RAPID CTP in assessing postreperfusion FIV and functional outcomes for both early- and late-presenting patients. NCCT e-Stroke volumes seems to represent a viable alternative in centers where access to advanced imaging is limited. Moreover, the future development of fusion maps of NCCT and CTP ischemic core estimates may improve upon the current performance of these tools as applied in isolation.

Recanalization Therapy for Acute Ischemic Stroke with Large Vessel Occlusion: Where We Are and What Comes Next?

In the past 5 years, the success of multiple randomized controlled trials of recanalization therapy with endovascular thrombectomy has transformed the treatment of acute ischemic stroke with large vessel occlusion. The evidence from these trials has now established endovascular thrombectomy as standard of care. This review will discuss the chronological evolution of large vessel occlusion treatment from early medical therapy with tissue plasminogen activator to the latest mechanical thrombectomy. Additionally, it will highlight the potential areas in endovascular thrombectomy for acute ischemic stroke open to exploration and further progress in the next decade.

Acute Ischaemic Stroke Successfully Treated with Thrombolytic Therapy and Endovascular Thrombectomy with Non-Contrast Computed Tomography and Computed Tomography Angiogram Protocol

Early endovascular thrombectomy leads to improved outcomes for patients with proximal occlusions when started within 6 h from onset of symptoms. We present a case illustrating the flow of events for a patient who underwent endovascular thrombectomy in our centre after conventional imaging – a brain non-contrast computed tomography (NCCT) and CT angiogram (CTA) – achieving a door-to-groin time of 195 min. The patient is a 65-year-old who presented with signs and symptoms of a left middle cerebral artery (MCA) territory infarct. His National Institute of Health Stroke Scale (NIHSS) score was 15 on presentation and his brain NCCT showed an Alberta Stroke Programme Early CT Score (ASPECTS) of 8. His CTA showed a left MCA distal M1 occlusion with focal calcification and stenosis of the proximal left internal carotid artery. He was subsequently thrombosed and underwent thrombectomy successfully, with a door-to-groin-puncture time of 195 min. A TICI 2b reperfusion was achieved. His NIHSS score improved to 9 over the next 2 days. For cases with straightforward NCCT and CTA with no contraindications, endovascular thrombectomy should be pursued without delay. A review of the current available literature for the usage of NCCT and CTA as well as the importance of ASPECTS scoring in patient selection for endovascular thrombectomy was included.

Location-Specific ASPECTS Paradigm in Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

Weighting neuroimaging findings based on eloquence can improve the predictive value of ASPECTS, possibly aiding in informed treatment decisions for acute ischemic stroke.

PURPOSE

Our aim was to study the contribution of region-specific ASPECTS infarction to acute ischemic stroke outcomes.

DATA SOURCES

We searched MEDLINE and EMBASE for reports on ASPECTS in patients with acute ischemic stroke from 2000 to March 2019.

STUDY SELECTION

Two investigators independently reviewed articles and extracted data. Three-month poor functional outcome defined as mRS >2 was the primary end point.

DATA ANALYSIS

A random-effects meta-analysis was performed to compare the association between infarct and mRS >2 among ASPECTS regions. Subanalyses included the following: laterality of stroke (left/right), imaging technique (NCCT or advanced imaging with DWI, CTP, or CTA), and interventional technique (IV-tPA/conservative management or mechanical thrombectomy).

DATA SYNTHESIS

M6 infarct was most associated with poor functional outcome (OR = 3.26; 95% CI, 2.21-4.80; P < .001). Pair-wise comparisons of ASPECTS regions regarding the association between infarct and mRS >2 were not significant, with the exception of M6 versus lentiform (P = .009). However, pair-wise comparisons among ASPECTS regions were not significant among subgroup analyses.

LIMITATIONS

Limitations were the heterogeneity of time points, neuroimaging modalities, and interventional techniques; limited studies for inclusion; publication bias among some comparisons; and the retrospective nature of included studies.

CONCLUSIONS

Our study indicated an unequal impact of some ASPECTS subregions in predicting outcomes of patients with acute ischemic stroke. Stroke laterality, imaging technique, and interventional technique subgroup analyses showed no differences among ASPECTS regions in predicting outcome. Investigation in larger cohorts is required to assess the association of ASPECTS with acute ischemic stroke outcome.

Impact of Initial Imaging Protocol on Likelihood of Endovascular Stroke Therapy

Background and Purpose:

Noncontrast head CT and CT perfusion (CTP) are both used to screen for endovascular stroke therapy (EST), but the impact of imaging strategy on likelihood of EST is undetermined. Here, we examine the influence of CTP utilization on likelihood of EST in patients with large vessel occlusion (LVO).

Methods:

We identified patients with acute ischemic stroke at 4 comprehensive stroke centers. All 4 hospitals had 24/7 CTP and EST capability and were covered by a single physician group (Neurology, NeuroIntervention, NeuroICU). All centers performed noncontrast head CT and CT angiography in the initial evaluation. One center also performed CTP routinely with high CTP utilization (CTP-H), and the others performed CTP optionally with lower utilization (CTP-L). Primary outcome was likelihood of EST. Multivariable logistic regression was used to determine whether facility type (CTP-H versus CTP-L) was associated with EST adjusting for age, prestroke mRS, National Institutes of Health Stroke Scale, Alberta Stroke Program Early CT Score, LVO location, time window, and intravenous tPA (tissue-type plasminogen activator).

Results:

Among 3107 patients with acute ischemic stroke, 715 had LVO, of which 403 (56%) presented to CTP-H and 312 (44%) presented to CTP-L. CTP utilization among LVO patients was greater at CTP-H centers (72% versus 18%, CTP-H versus CTP-L, P <0.01). In univariable analysis, EST rates for patients with LVO were similar between CTP-H versus CTP-L (46% versus 49%). In multivariable analysis, patients with LVO were less likely to undergo EST at CTP-H (odds ratio, 0.59 [0.41–0.85]). This finding was maintained in multiple patient subsets including late time window, anterior circulation LVO, and direct presentation patients. Ninety-day functional independence (odds ratio, 1.04 [0.70–1.54]) was not different, nor were rates of post-EST PH-2 hemorrhage (1% versus 1%).

Conclusions:

We identified an increased likelihood for undergoing EST in centers with lower CTP utilization, which was not associated with worse clinical outcomes or increased hemorrhage. These findings suggest under-treatment bias with routine CTP.

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.

The Safety and Efficacy of Endovascular Treatment for Patients With ASPECTS<6 in Anterior Circulation Stroke: A Meta-Analysis and Subgroup Analysis by Imaging Techniques

BACKGROUND

Endovascular treatment (EVT) is merely recommended as class of recommendation IIb for patients with ASPECTS <6 according to the American Heart Association guideline 2019. In addition, the best determined imaging technique for EVT in patient with ASPECTS<6 remains unknown. The objective of this study was to define the safety and efficacy of EVT for patients with ASPECTS<6 and investigate the superiority between MRI and CT for patient selection.

METHODS

A systematic search of PubMed, EMBASE, The Cochrane Library and other additional sources was performed for studies published with no publication period. Our study was conducted corresponding to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRIMA) guidelines. The analysis was performed using the Comprehensive Meta-Analysis (CMA) 2.0.

RESULTS

Five studies reporting data from 844 participants were included in our analysis according to the inclusion criteria. Consequently, EVT was associated with statistically significant higher functional independence compared with MT (OR 5.401, 95% CI 3.227-9.041). Whereas EVT was found to be related to lower mortality compared with MT based on eligible data (OR 0.461, 95% CI 0.329-0.647). No significant difference was identified in sICH between EVT and MT (OR 1.075, 95% CI 0.452-2.558).

CONCLUSION

According to the results of our study, we suggested that EVT is a preferred therapy in ACS patients with ASPECTS<6 in consideration of efficacy and safety. Furthermore, MRI did not show superiority over CT as no statistical difference was detected in all subgroups.

Posterior circulation stroke: an easily overlooked complication of catheter ablation of atrial fibrillation

Catheter ablation of atrial fibrillation (AF) has established itself as a safe and proven rhythm control strategy for selected patients with AF over the past decade. Thromboembolic complications of catheter ablation are becoming rare in anticoagulated patients with a risk of stroke reported as 0.3%. A particular challenge is posed by clinical presentation due to ischaemic stroke involving the posterior circulation following catheter ablation because of its substantial differences from the carotid territory stroke, making the timely diagnosis and treatment very difficult. It is crucial to keep an index of clinical suspicion in patients presenting with neurological deficits related to vertebrobasilar circulation following ablation. We describe the case of a man who presented with dizziness and palpitations after radiofrequency catheter ablation of AF. He was found to be in AF with a rapid ventricular response. His dizziness was initially attributed to the cardiac dysrhythmia. As his symptoms continued despite heart rate control, he underwent further investigations and was eventually diagnosed with a posterior circulation stroke resulting in left cerebellar infarction. He was treated with antiplatelet therapy and improved significantly over the following few days. We review and present an up-to-date brief literature review on the complications of catheter ablation of AF and describe pathophysiology, clinical features, diagnosis and treatment options for posterior circulation stroke after AF ablation. This case aims to raise awareness among clinicians about posterior circulation stroke after AF ablation.

Endovascular treatment or general treatment: how should acute ischemic stroke patients choose to benefit from them the most?: A systematic review and meta-analysis

BACKGROUND

Acute ischemic stroke due to large-vessel occlusion is a leading cause of death and disability, and therapeutic time window was limited to 4.5 hour when treated with intravenous thrombolysis. It has been acknowledged that endovascular treatment (EVT) is superior to general treatment (only medication, including intravenous recombinant tissue plasminogen activator (rt-PA)) in improving the outcome of AIS since 2015. However, the benefits were limited to improvement of functional outcomes and functional independence. Hence, this meta-analysis was conducted to summarize the benefits of EVT for acute ischemic stroke, explore underlying indications of EVT for AIS patients and suggest implications for clinical practice and future research.

METHODS

A search was performed to identify eligible studies in PubMed, Scopus and Web of Science updated to February 5, 2019. Functional outcomes, the modified Rankin Scale (mRS) 0-1, mRS 0-2, all-cause mortality, symptomatic intracerebral hemorrhage and asymptomatic intracerebral hemorrhage (aICH) at 90 days were selected as outcomes. Data was pooled to calculate the odds ratio (OR) and 95% confidence interval (CI). Heterogeneity, subgroup analysis, sensitivity analysis and publication bias were also performed in this meta-analysis.

RESULTS

Eighteen studies comprising 3831 patients were included and analyzed in this meta-analysis. In comparison with general treatment, improved functional outcomes (mRS 0-1: OR = 1.68, 95% CI = 1.43-1.97, inconsistency index [I = 57%, P < .00001; mRS 0-2: OR = 1.78, 95% CI = 1.55-2.03, I = 69%, P < .00001), reduced risk of all-cause mortality (OR = 0.82, 95% CI = 0.70-0.98, I = 27%, P = .03) but higher risk of aICH (OR = 1.43, 95% CI = 1.05-1.95, I = 0%, P = .02) at 90 days were found in AIS patients treated with EVT. Age < 70, National Institutes of Health Stroke Scale ≥20 and maximum delay for invention>5 hours could improve clinical outcomes following EVT. In sensitivity analysis, it showed that 2 studies had a great influence on the pooled ORs. No potential publication bias was found in this meta-analysis.

CONCLUSION

Taken together, EVT, which led to improved functional outcomes and decreased risk of death, is superior to general treatment for AIS patients with age < 70, National Institutes of Health Stroke Scale ≥20 and maximum delay for invention>5 hours. Moreover, it suggests that "with mechanical thrombectomy" is potential favorable factor for improving aICH in comparison with general treatment.

Spatial Resolution and the Magnitude of Infarct Volume Measurement Error in DWI in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Infarct volume in acute ischemic stroke is an important prognostic marker and determines endovascular treatment decisions. This study evaluates the magnitude and potential clinical impact of the error related to partial volume effects in infarct volume measurement on diffusion-weighted MR imaging in acute stroke and explores how increasing spatial resolution could reduce this error.

MATERIALS AND METHODS

Diffusion-weighted imaging of 393 patients with acute stroke, of whom 56 had anterior circulation large-vessel occlusion, was coregistered to standard space. Lesion boundaries were manually segmented. A 3D lesion-volume model was resampled for voxel sizes from 4 × 4 × 8 to 1 × 1 × 2 mm, and the surface-volume, corresponding to the partial volume error, was calculated. The number of cases with anterior circulation large-vessel occlusion, in which the endovascular therapy core threshold of 70 mL was contained within the margin of error, was calculated as a function of imaging resolution.

RESULTS

The mean infarct core volume was 27.2 ± 49.9 mL. The mean surface volume was 14.7 ± 20.8 mL for 2 × 2 × 4 mm resolution and 7.4 ± 10.7 mL for 1 × 1 × 2 mm resolution. With a resolution of 2 × 2 × 4 mm, 70 mL was contained within the margin of error in 7/56 cases (12.5%) with large-vessel occlusion, while with a 1 × 1 × 2 mm voxel size, the margin of error was 3/56 (5%). The lesion-volume range of potentially misclassified lesions dropped from 46.5-94.1 mL for a 2 × 2 × 4 mm resolution to 64.4-80.1 mL for a 1 × 1 × 2 mm resolution.

CONCLUSIONS

Partial volume effect is an important source of error in infarct volume measurement in acute stroke. Increasing spatial resolution substantially decreases the mean error. Standard use of high-resolution DWI should be considered to increase the reliability of infarct volume measurements.

Reducing door-to-reperfusion time in acute stroke endovascular therapy using magnetic resonance imaging as a screening modality

Background

The feasibility of performing MRI first for patients with suspected hyperacute stroke in real-world practice has not been fully examined. Moreover, most past studies of reducing door-to-reperfusion time (DRT) in endovascular treatment (EVT) were conducted using CT. The aim of this study was to evaluate the feasibility of an MRI-first policy and to examine the effects of a quality improvement (QI) process for reducing DRT using MRI.

Methods

From January 2013 to December 2018, consecutive patients with acute stroke who came to hospital directly and were treated with emergent EVT were prospectively enrolled into the present study. In principle, MRI was performed first for patients with suspected acute stroke. A step-by-step QI process for decreasing DRT was adopted during this period. Time metrics for EVT were compared between specific time periods.

Results

A total of 180 patients (71 women; median age 76 years (range 69–64); National Institutes of Health Stroke Scale score 17 (range 10–23)) were included in the present study. More patients in the late phase were managed with the MRI-first policy (p<0.001). DRT (199 min in Phase 1, 135 min in Phase 2, 129 min in Phase 3, and 121 min in Phase 4, p<0.001) was significantly reduced across the phases. The percentage of patients with DRT <120 min increased significantly across time periods (p<0.001). Symptomatic intracerebral hemorrhage did not increase across phases (p=0.575).

Conclusion

An MRI-first policy was feasible, and DRT decreased considerably with a step-by-step QI process. This process may be applicable to other hospitals.

Optimizing Patient Selection for Endovascular Treatment in Acute Ischemic Stroke (SELECT): A Prospective, Multicenter Cohort Study of Imaging Selection

OBJECTIVE

The primary imaging modalities used to select patients for endovascular thrombectomy (EVT) are noncontrast computed tomography (CT) and CT perfusion (CTP). However, their relative utility is uncertain. We prospectively assessed CT and CTP concordance/discordance and correlated the imaging profiles on both with EVT treatment decisions and clinical outcomes.

METHODS

A phase 2, multicenter, prospective cohort study of large-vessel occlusions presented up to 24 hours from last known well was conducted. Patients received a unified prespecified imaging evaluation (CT, CT angiography, and CTP with Rapid Processing of Perfusion and Diffusion software mismatch determination). The treatment decision, EVT versus medical management, was nonrandomized and at the treating physicians' discretion. An independent, blinded, neuroimaging core laboratory adjudicated favorable profiles based on predefined criteria (CT:Alberta Stroke Program Early CT Score ≥ 6, CTP:regional cerebral blood flow (<30%) < 70ml with mismatch ratio ≥ 1.2 and mismatch volume ≥ 10ml).

RESULTS

Of 4,722 patients screened from January 2016 to February 2018, 361 patients were included. Two hundred eighty-five (79%) received EVT, of whom 87.0% had favorable CTs, 91% favorable CTPs, 81% both favorable profiles, 16% discordant, and 3% both unfavorable. Favorable profiles on the 2 modalities correlated similarly with 90-day functional independence rates (favorable CT = 56% vs favorable CTP = 57%, adjusted odds ratio [aOR] = 1.91, 95% confidence interval [CI] = 0.40-9.01, p = 0.41). Having a favorable profile on both modalities significantly increased the odds of receiving thrombectomy as compared to discordant profiles (aOR = 3.97, 95% CI = 1.97-8.01, p < 0.001). Fifty-eight percent of the patients with favorable profiles on both modalities achieved functional independence as compared to 38% in discordant profiles and 0% when both were unfavorable (p < 0.001 for trend). In favorable CT/unfavorable CTP profiles, EVT was associated with high symptomatic intracranial hemorrhage (sICH) (24%) and mortality (53%) rates.

INTERPRETATION

Patients with favorable imaging profiles on both modalities had higher odds of receiving EVT and high functional independence rates. Patients with discordant profiles achieved reasonable functional independence rates, but those with an unfavorable CTP had higher adverse outcomes. Ann Neurol 2020;87:419-433.

Noncontrast Computed Tomography Alberta Stroke Program Early CT Score May Modify Intra-Arterial Treatment Effect in DAWN

Background and Purpose—

It is unknown whether noncontrast computed tomography (NCCT) can identify patients who will benefit from intra-arterial treatment (IAT) in the extended time window. We sought to characterize baseline Alberta Stroke Program Early CT Score (ASPECTS) in DAWN (DWI or CTP Assessment With Clinical Mismatch in the Triage of Wake-Up and Late Presenting Strokes Undergoing Neurointervention With Trevo) and to assess whether ASPECTS modified IAT effect.

Methods—

Core lab adjudicated ASPECTS scores were analyzed. The trial cohort was divided into 2 groups by qualifying imaging (computed tomography versus magnetic resonance imaging). ASPECTS-by-treatment interaction was tested for the trial coprimary end points (90-day utility-weighted modified Rankin Scale (mRS) score and mRS, 0–2), mRS 0 to 3, and ordinal mRS. ASPECTS was evaluated separately as an ordinal and a dichotomized (0–6 versus 7–10) variable.

Results—

Of 205 DAWN subjects, 123 (60%) had NCCT ASPECTS, and 82 (40%) had diffusion weighted imaging ASPECTS. There was a significant ordinal NCCT ASPECTS-by-treatment interaction for 90-day utility-weighted mRS (interaction P =0.04) and mRS 0 to 2 (interaction P =0.02). For both end points, IAT effect was more pronounced at higher NCCT ASPECTS. The dichotomized NCCT ASPECTS-by-treatment interaction was significant only for mRS 0 to 2 (interaction P =0.04), where greater treatment benefit was seen in the ASPECTS 7 to 10 group (odds ratio, 7.50 [2.71–20.77] versus odds ratio, 0.48 [0.04–5.40]). A bidirectional treatment effect was observed in the NCCT ASPECTS 0 to 6 group, with treatment associated with not only more mRS 0 to 3 outcomes (50% versus 25%) but also more mRS 5 to 6 outcomes (40% versus 25%). There was no significant modification of IAT effect by diffusion weighted imaging ASPECTS.

Conclusions—

Baseline NCCT ASPECTS appears to modify IAT effect in DAWN. Higher NCCT ASPECTS was associated with greater benefit from IAT. No treatment interaction was observed for diffusion weighted imaging ASPECTS.

Prospective Endovascular Treatment in Acute Ischemic Stroke Evaluating Non-Contrast Head CT versus CT Perfusion (PLEASE No CTP)

Background

Studies have shown a lack of agreement of computed tomography perfusion (CTP) in the selection of acute ischemic stroke (AIS) patients for endovascular treatment.

Purpose

To demonstrate whether non-contrast computed tomography (CT) within 8 h of symptom onset is comparable to CTP imaging.

Methods

Prospective study of consecutive anterior circulation AIS patients with a National Institute of Health Stroke Scale (NIHSS) score > 7 presenting within 8 h of symptom onset with endovascular treatment. All patients had non-contrast CT, CT angiography, and CTP. The neuro-interventionalist was blinded to the results of the CTP and based the treatment decision using the Alberta Stroke Program Early CT score (ASPECTS). Baseline demographics, co-morbidities, and baseline NIHSS scores were collected. Outcomes were modified Rankin scale (mRS) score at discharge and in-hospital mortality. Good outcomes were defined as a mRS score of 0-2.

Results

283 AIS patients were screened for the trial, and 119 were enrolled. The remaining patients were excluded for: posterior circulation stroke, no CTP performed, could not obtain consent, and NIHSS score < 7. Mean -NIHSS score at admission was 16.8 ± 3, and mean ASPECTS was 8.4 ± 1.4. There was no statistically significant correlation with CTP penumbra and good outcomes: 50 versus 47.8% with no penumbra present (p = 0.85). In patients without evidence of CTP penumbra, there was 22.5% mortality compared to 22.1% mortality in patients with a CTP penumbra. If ASPECTS ≥7, 64.6% had good outcome versus 13.3% if ASPECTS < 7 (p < 0.001). Patients with an ASPECTS ≥7 had 10% mortality versus 51.4% in patients with an ASPECTS < 7 (p < 0.001).

Conclusions

CTP penumbra did not identify patients who would benefit from endovascular treatment when patients were selected with non-contrast CT ASPECTS ≥7. There is no correlation of CTP penumbra with good outcomes or mortality. Larger prospective trials are warranted to justify the use of CTP within 6 h of symptom onset.

NCCT and CTA-based imaging protocol for endovascular treatment selection in late presenting or wake-up strokes

Introduction

Recently, the benefit of selecting patients for endovascular treatment (EVT) beyond the 6-hour time window using a tissue-based approach was demonstrated in two randomized trials. The optimal imaging protocol for selecting patients is under debate, and it is still unknown if a simpler and faster protocol may adequately select patients with wake-up stroke (WUS) and late-presenting stroke (LPS) for EVT.

Objective

To compare outcomes of patients submitted to EVT presenting within 6 hours of symptom onset or 6–24 hours after last seen well, selected using non-contrast computed tomography (NCCT) and CT angiography (CTA).

Methods

An observational study was performed, which included consecutive patients with anterior circulation ischemic stroke with large vessel occlusion treated with EVT. Patients presenting within 6 hours were treated if their NIH Stroke Scale (NIHSS) score was ≥6 and Alberta Stroke Program Early CT score (ASPECTS) was ≥6, while patients presenting with WUS or 6–24 hours after last seen well (WUS/LPS) were treated if their NIHSSscore was ≥12 and ASPECTS was ≥7.

Results

249 patients were included, 63 of whom were in the WUS/LPS group. Baseline characteristics were similar between groups, except for longer symptom-recanalization time, lower admission NIHSS (16 vs 17, P=0.038), more frequent tandem occlusions (25.4% vs 11.8%, P=0.010), and large artery atherosclerosis etiology (22.2% vs 11.8%, P=0.043) in the WUS/LPS group. No differences in symptomatic intracranial hemorrhage, peri-procedural complications or mortality were found between groups. Three-month functional independence was similar in both groups (65.1% in WUS/LPS vs 57.0% in ≤6 hours, P=0.259) and no differences were found after adjustment for confounders.

Conclusions

This real-world observational study suggests that EVT may be safe and effective in patients with WUS and LPS selected using clinical-core mismatch (high NIHSS/high ASPECTS in NCCT).

Diagnosis and Management of Acute Ischemic Stroke

Acute ischemic stroke (AIS) is among the leading causes of death and long-term disability. Intravenous tissue plasminogen activator has been the mainstay of acute therapy. Recently, several prospective randomized trials documented the value of endovascular revascularization in selected patients with large-vessel occlusion within the anterior circulation. This finding has led to a paradigm shift in the management of AIS, including wide adoption of noninvasive neuroimaging to assess vessel patency and tissue viability, with the supplemental and independent use of intravenous tissue plasminogen activator to improve clinical outcomes. In this article, we review the landmark studies on management of AIS and the current position on the diagnosis and management of AIS. The review also highlights the importance of early stabilization and prompt initiation of therapeutic interventions before, during, and after the diagnosis of AIS within and outside of the hospital.

Optimized Management of Endovascular Treatment for Acute Ischemic Stroke

This manuscript describes a streamlined protocol for the management of patients with acute ischemic stroke, which aims at the minimization of time from hospital admission to reperfusion. Rapid restoration of cerebral blood flow 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 carefully 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. Target times for every step were established. Actually achieved times were prospectively recorded along with clinical data and imaging scores for all endovascularly treated stroke patients. These data were regularly analyzed and discussed in interdisciplinary team meetings. Potential issues were evaluated and all staff involved was trained to adhere to the SOP. This streamlined patient management approach and enhanced interdisciplinary collaboration reduced time from patient admission to reperfusion significantly and was accompanied by a beneficial effect on clinical outcomes.

Usefulness of multiphase computed tomography angiography in a patient with transient ischemic attack in the hyperacute phase: A case report

RATIONALE

Patients with transient ischemic attack (TIA) have the possibility of developing stroke in the future. To prevent recurrent TIA or future stroke, identifying the cause of TIA is important. However, about two-third of patients with TIA have negative findings on diffusion-weighted imaging (DWI).We present a case of TIA, the cause of which was identified using multiphase computed tomography angiography (MCTA) in the hyperacute phase of the disease.

PATIENT CONCERNS

The patient was a 57-year-old man who was admitted to the emergency department for right-side weakness persisting for 1 hour.

DIAGNOSES

Occlusion of the proximal M3 segment of the left middle cerebral artery territory was found on the initial MCTA.

OUTCOMES

The weakness completely resolved at 2 hours after symptom onset, and there was no acute infarction on the initial diffusion-weighted magnetic resonance imaging (MRI) on the same day. Follow-up MCTA on the next day showed recanalization of the left M3 segment. Follow-up diffusion-weighted MRI showed focal acute infarction in the left middle cerebral artery territory.

LESSONS

MCTA could identify distal occlusion of the anterior circulation in patients with cardioembolic TIA in the hyperacute phase with negative DWI findings.

Improving Regional Stroke Systems of Care

PURPOSE OF REVIEW

Acute ischemic stroke (AIS) care is rapidly evolving. This review discusses current diagnostic, therapeutic, and process models that can expedite stroke treatment to achieve best outcomes.

RECENT FINDINGS

Use of stent retrievers after selection via advanced imaging is safe and effective, and is an important option for AIS patients with large vessel occlusion (LVO). Significant time delays occur before and during patient transfers, and upon comprehensive stroke center (CSC) arrival, and have deleterious effects on functional outcome. Removing obstacles, enhancing inter-facility communication, and creating acute stroke management processes and protocols are paramount strategies to enhance network efficiency. Inter-departmental CSC collaboration can significantly reduce door-to-treatment times. Streamlined stroke systems of care may result in higher treatment rates and better functional outcomes for AIS patients, simultaneously conserving healthcare dollars. Stroke systems of care should be structured regionally to minimize time to treatment. A proactive approach must be employed; a management plan incorporating stroke team prenotification and parallel processes between departments can save valuable time, maximize brain salvage, and reduce disability from stroke.

Ischemic Stroke Treatment Trials: Neuroimaging Advancements and Implications

There have been significant advancements in the treatment of acute ischemic stroke in the last 2 decades. Recent trials have placed a significant emphasis on minimizing the time from symptom onset to stroke treatment by reperfusion therapies, which decreases the cerebral infarct volume and improves clinical outcomes. These clinical advances have paralleled and been aided by advances in neuroimaging. However, controversy remains regarding how much time should be spent on neuroimaging evaluation versus expediting patient treatment. In this review article, we examine the key endovascular stroke trials published in the past 25 years, and we briefly highlight the failures and successes of endovascular stroke trials performed in the past 4 years. We also discuss the advantages and disadvantages of using time from symptom onset versus neuroimaging in determining endovascular stroke therapy candidacy.

Cost Analysis of the Addition of Hyperacute Magnetic Resonance Imaging for Selection of Patients for Endovascular Stroke Therapy

Background and Purpose

Patient selection is important to determine the best candidates for endovascular stroke therapy. In application of a hyperacute magnetic resonance imaging (MRI) protocol for patient selection, we have shown decreased utilization with improved outcomes. A cost analysis comparing the pre- and post-MRI protocol time periods was performed to determine if the previous findings translated into cost opportunities.

Materials and Methods

We retrospectively identified individuals considered for endovascular stroke therapy from January 2008 to August 2012 who were ≤8 h from stroke symptoms onset. Patients prior to April 30, 2010 were selected based on results of the computed tomography/computed tomography angiography alone (pre-hyperacute), whereas patients after April 30, 2010 were selected based on results of MRI (post-hyperacute MRI). Demographic, outcome, and financial information was collected. Log-transformed average daily direct costs were regressed on time period. The regression model included demographic and clinical covariates as potential confounders. Multiple imputation was used to account for missing data.

Results

We identified 267 patients in our database (88 patients in pre-hyperacute MRI period, 179 in hyperacute MRI protocol period). Patient length of stay was not significantly different in the hyperacute MRI protocol period as compared to the pre-hyperacute MRI period (10.6 vs. 9.9 days, p < 0.42). The median of average daily direct costs was reduced by 24.5% (95% confidence interval 14.1-33.7%, p < 0.001).

Conclusions

Use of the hyperacute MRI protocol translated into reduced costs, in addition to reduced utilization and better outcomes. MRI selection of patients is an effective strategy, both for patients and hospital systems.

Computed Tomographic Perfusion Selection and Clinical Outcomes After Endovascular Therapy in Large Vessel Occlusion Stroke

Background and Purpose—

Different imaging paradigms have been used to select patients for endovascular therapy in stroke. We sought to determine whether computed tomographic perfusion (CTP) selection improves endovascular therapy outcomes compared with noncontrast computed tomography alone.

Methods—

Review of a prospectively collected registry of anterior circulation stroke patients undergoing stent-retriever thrombectomy at a tertiary care center between September 2010 and March 2016. Patients undergoing CTP were compared with those with noncontrast computed tomography alone. The primary outcome was the shift in the 90-day modified Rankin scale (mRS).

Results—

A total of 602 patients were included. CTP-selected patients (n=365, 61%) were younger ( P =0.02) and had fewer comorbidities. CTP selection (n=365, 61%) was associated with a favorable 90-day mRS shift (adjusted odds ratio [aOR]=1.49; 95% confidence interval [CI], 1.06–2.09; P =0.02), higher rates of good outcomes (90-day mRS score 0–2: 52.9% versus 40.4%; P =0.005), modified Thrombolysis in Cerebral Infarction-3 reperfusion (54.8% versus 40.1%; P <0.001), smaller final infarct volumes (24.7 mL [9.8–63.1 mL] versus 34.6 mL [13.1–88 mL]; P =0.017), and lower mortality (16.6% versus 26.8%; P =0.005). When matched on age, National Institutes of Health Stroke Scale (NIHSS) score, and glucose (n=424), CTP remained associated with a favorable 90-day mRS shift ( P =0.016), lower mortality ( P =0.02), and higher rates of reperfusion ( P <0.001). CTP better predicted functional outcomes in patients presenting after 6 hours (as assessed by comparison of logistic regression models: Akaike information criterion: 199.35 versus 287.49 and Bayesian information criterion: 196.71 versus 283.27) and those with an Alberta Stroke Program Early Computed Tomography Score ≤7 (Akaike information criterion: 216.69 versus 334.96 and Bayesian information criterion: 213.6 versus 329.94).

Conclusions—

CTP selection is associated with a favorable mRS shift in patients undergoing stent-retriever thrombectomy. Future prospective studies are warranted.

Rapid Endovascular Treatment of Acute Ischemic Stroke: What a General Radiologist Should Know

Stroke is the second leading cause of mortality and the third leading cause of disability-adjusted life-years worldwide. For each minute of an ischemic stroke, an estimated 1.9 million brain cells die. The year 2015 saw the unprecedented publication of 5 multicentre, randomized, controlled trials. These studies showed that patients with acute ischemic stroke caused by large-vessel thrombus occlusion of the proximal anterior circulation had significantly reduced disability at 90 days when treated with endovascular thrombectomy and usual stroke care compared to usual stroke care alone. As a result, endovascular thrombectomy is now the new North American and European standard of care for suitable patients with acute ischemic stroke caused by large-vessel proximal anterior circulation occlusion. We review key take-home messages in this paradigm shift for radiologists, including the importance of time and workflow efficiency, what currently constitutes appropriate preimaging patient selection and imaging criteria, the use of newer generation thrombectomy devices, safety outcomes, as well as further areas still in need of elucidation.

Effects of Workflow Optimization in Endovascularly Treated Stroke Patients - A Pre-Post Effectiveness Study

Endovascular treatment of acute ischemic stroke has become standard of care for patients with large artery occlusion. Early restoration of blood flow is crucial for a good clinical outcome. We introduced an interdisciplinary standard operating procedure (SOP) between neuroradiologists, neurologists and anesthesiologists in order to streamline patient management. This study analyzes the effect of optimized workflow on periprocedural timings and its potential influence on clinical outcome. Data were extracted from a prospectively maintained university hospital stroke database. The standard operating procedure was established in February 2014. Of the 368 acute stroke patients undergoing endovascular treatment between 2008 and 2015, 278 patients were treated prior to and 90 after process optimization. Outcome measures were periprocedural time intervals and residual functional impairment. After implementation of the SOP, time from symptom onset to reperfusion was significantly reduced (median 264 min prior and 211 min after SOP-introduction (IQR 228–32 min and 161–278 min, respectively); P<0.001). Especially faster supply of imaging and prompt transfer of patients to the angiography suite contributed to this effect. Time between hospital admission and groin puncture was reduced by half after process optimization (median 64 min after versus 121 min prior to SOP-introduction (IQR 54–77 min and 96–161 min, respectively); P<0.001). Clinical outcome was significantly better after workflow optimization as measured with the modified Rankin Scale (common odds ratio (OR) 0.56; 95% CI 0.32–0.98; P = 0.038). Optimization of workflow and interdisciplinary teamwork significantly improved the outcome of patients with acute ischemic stroke due to a significant reduction of in-hospital examination, transportation, imaging and treatment times.

Improving the Evaluation of Collateral Circulation by Multiphase Computed Tomography Angiography in Acute Stroke Patients Treated with Endovascular Reperfusion Therapies

Good collateral circulation (CC) is associated with favorable outcomes in acute stroke, but the best technique to evaluate collaterals is controversial. Single-phase computed tomography angiography (sCTA) is widely used but lacks temporal resolution. We aim to compare CC evaluation by sCTA and multiphase CTA (mCTA) as predictors of outcome in endovascular treated patients.

METHODS

Consecutive endovascular treated patients with M1 middle cerebral artery (MCA) or terminal intracranial carotid artery (TICA) occlusion confirmed by sCTA were included. Two more CTA acquisitions with 8- and 16-second delays were performed for mCTA. Endovascular thrombectomy was performed independently of the CC status according to a local protocol [Alberta Stroke Program Early CT score (ASPECTS) >6, modified Rankin scale (mRS) score <3]. CC on sCTA and mCTA were compared.

RESULTS

108 patients were included. Their mean age was 69.6 ± 13 years and their median National Institutes of Health Stroke Scale (NIHSS) score was 17 (interquartile range 8). 79 (73.1%) had M1 MCA and 29 (26.9%) TICA occlusions. The mean time from symptom onset to CTA was 146.8 ± 96.5 min. On sCTA, 50.9% patients presented good CC vs. 57.5% on mCTA. Good CC status in both sCTA and mCTA had a lower 24-hour infarct volume (27.4 vs. 74.8 cm³ on sCTA, p = 0.04; 17.2 vs. 97.8 cm³ on mCTA, p < 0.01). However, only good CC on mCTA was associated with lower 24-hour (5 vs. 8.5, p = 0.04) and median discharge NIHSS (2 vs. 4.5, p = 0.04) scores and functional independency (mRS score <3) at 3 months (76.9 vs. 23.1%, p < 0.01). In a logistic regression model including age, NIHSS, ASPECTS and recanalization, only age (OR 0.96, 95% CI 0.93-0.99, p = 0.02) and good CC on mCTA (OR 5, 95% CI 1.99-12.6, p < 0.01) were independent predictors of functional outcome at 3 months.

CONCLUSION

CC evaluation by mCTA is a better prognostic marker than CC evaluation by sCTA for clinical and functional endpoints in acute stroke patients treated with endovascular thrombectomy.

Multimodal CT Imaging: Time to Treatment and Outcomes in the IMS III Trial

BACKGROUND AND PURPOSE

The importance of time in acute stroke is well-established. Using the Interventional Management of Stroke III trial data, we explored the effect of multimodal imaging (CT perfusion and/or CT angiography) versus noncontrast CT alone on time to treatment and outcomes.

MATERIALS AND METHODS

We examined 3 groups: 1) subjects with baseline CTP and CTA (CTP+CTA), 2) subjects with baseline CTA without CTP (CTA), and 3) subjects with noncontrast head CT alone. The demographics, treatment time intervals, and clinical outcomes in these groups were studied.

RESULTS

Of 656 subjects enrolled in the Interventional Management of Stroke III trial, 90 (13.7%) received CTP and CTA, 216 (32.9%) received CTA (without CTP), and 342 (52.1%) received NCCT alone. Median times for the CTP+CTA, CTA, and NCCT groups were as follows: stroke onset to IV tPA (120.5 versus 117.5 versus 120 minutes; P = .5762), IV tPA to groin puncture (77.5 versus 81 versus 91 minutes; P = .0043), groin puncture to endovascular therapy start (30 versus 38 versus 44 minutes; P = .0001), and endovascular therapy start to end (63 versus 46 versus 74 minutes; P < .0001). Compared with NCCT, the CTA group had better outcomes in the endovascular arm (OR, 2.12; 95% CI, 1.36-3.31; adjusted for age, NIHSS score, and time from onset to IV tPA). The CTP+CTA group did not have better outcomes compared with the NCCT group.

CONCLUSIONS

Use of CTA with or without CTP did not delay IV tPA or endovascular therapy compared with NCCT in the Interventional Management of Stroke III trial.

Imaging Paradigms in Acute Ischemic Stroke: A Pragmatic Evidence-based Approach

Online supplemental material is available for this article.