The Alberta Stroke Program Early CT Score in Clinical Practice: What have We Learned?

Cerebral Venous Drainage in Patients With Space-Occupying Middle Cerebral Artery Infarction: Effects on Functional Outcome After Hemicraniectomy

Background: Cerebral venous drainage might influence brain edema characteristics and functional outcome of patients with severe ischemic stroke. The purpose of the study was to evaluate whether hypoplasia of transverse sinuses or the internal jugular veins is associated with poor functional outcome in patients with space-occupying middle cerebral artery (MCA) infarction who underwent decompressive surgery. Methods: We performed a retrospective analysis of patients with space-occupying MCA infarction treated with decompressive surgery at our university hospital. The transverse sinuses and the internal jugular veins were evaluated on baseline images and categorized as normal, hypoplastic or occluded. We defined composite variables for ipsilateral, contralateral or any abnormal cerebral venous drainage. We assessed the functional outcome at 12 months with the modified Rankin scale (mRS) score and defined poor functional outcome as mRS scores 5 and 6. Results: We analyzed 88 patients with available baseline imaging data [mean [SD] patient age 53 (±9) years; median[IQR] time to decompressive surgery 31(22-51) h]. At 12 months 44 patients (50%) had a poor outcome. In univariate analysis neither ipsilateral (OR 1.98;95%CI: 0.75-5.40), nor contralateral (OR 1.56;95%CI: 0.59-4.24) or any (OR 1.6; 95%CI: 0.68-3.79) hypoplasia or occlusion of venous drainage were significantly associated with poor functional outcome. In multivariate analyses, higher patient age (OR 1.07;95%CI 1.01-1.14) and baseline stroke severity (OR 3.42;95%CI 1.31-9.40) were independent predictors of poor functional outcome, but not ipsilateral hypoplasia or occlusion of venous drainage (OR 1.31;95%CI 0.47-3.67). Conclusions: The cerebral venous drainage pattern was not significantly associated with poor functional outcome in our cohort of patients with space-occupying MCA infarction who underwent decompressive surgery.

Neuroimaging, serum biomarkers, and patient characteristics as predictors of upper limb functioning 12 weeks after acute stroke: an observational, prospective study

OBJECTIVE

To evaluate the potential of neuroimaging, serum biomarkers, stroke etiology, and clinical characteristics as predictors of upper limb functioning 12 weeks after stroke.

METHODS

This was a prospective, observational study of patients (18-85 years-old) hospitalized due to acute ischemic stroke in the territory of the middle cerebral artery. Patients were hospitalized at a stroke rehabilitation center, where they underwent a standardized rehabilitation program. Clinical, imagiology, laboratory (biomarkers: C-reactive protein, D-dimer, and fibrinogen, and S100 calcium binding protein β [S100β]), and functionality assessments were conducted four different times: within 24 hours, and at 48 hours, 3 weeks, and 12 weeks after acute stroke.

RESULTS

Upper limb functioning at 12 weeks was significantly associated with Alberta Stroke Program Early CT Score (ASPECTS) score (OR:2.012 [CI:1.349-3.000]; P = 0.001) and S100β protein levels (OR:0.997 [CI:0.994-0.999]; P = 0.007). Advanced age was associated with poor upper limb functioning. S100β protein levels < 140.5 ng/L at 48 hours and ASPECTS scores ≥ 7.5 within 24 hours of admission predicted good hand functioning at 12 weeks. Upper limb functioning and general functioning were significantly correlated (P < 0.001), with strong negative correlations (all correlation coefficients ≤-0.586) for all comparisons.

CONCLUSION

ASPECTS score ≥ 8 within 24 hours and S100β protein < 140.5 ng/L at 48 hours predict better upper limb functioning, while advanced age predicts worse upper limb functioning 12 weeks after stroke.

Early management of acute cerebrovascular accident

PURPOSE OF REVIEW

Stroke is common and often presents as a neurologic emergency that requires rapid evaluation and treatment to minimize debilitation. Recent advances in therapy expanded time windows for intra-arterial thrombectomy in ischemic stroke, and surgical interventions for clot evacuation in large intracranial hemorrhage have recently proven feasible. This review discusses recent data regarding new therapeutic options in both ischemic and hemorrhagic stroke, notably in scenarios in which therapy was previously limited to supportive care.

RECENT FINDINGS

Recent data show that intra-arterial therapy in ischemic stroke provides both benefit in outcomes and potential for further advancements in care. Therapeutic windows for endovascular treatment of a cerebral vessel occlusion now extend to 6 h, and recent data suggest this may increase further to 24 h. Intervention in hemorrhagic stroke remains limited to reversal of coagulopathy and hypertension; however, surgical techniques are underway and may prove beneficial in some cases.

SUMMARY

Advancing therapeutics in ischemic and hemorrhagic stroke are changing acute care intervention and broadening potential candidates for what were once thought to be nonintervenable conditions. Execution of best practices in stroke will continue to evolve and will require understanding advanced imaging techniques, as well as selection criteria for procedural and surgical interventions.

Infarct Core Expansion on Computed Tomography before and after Intravenous Thrombolysis

PURPOSE

Infarct core can expand rapidly in acute stroke patients receiving intravenous tissue plasminogen activator (IV t-PA). We investigated changes in the extent of infarct core during IV t-PA treatment, and explored the associative factors of this infarct core expansion in patients with proximal artery occlusion.

MATERIALS AND METHODS

We included patients who were considered for sequential intra-arterial therapy (IAT) due to occlusion of intracranial proximal artery after IV t-PA. Patients who had a baseline Alberta Stroke Program Early Computed Tomography (CT) Score (ASPECTS) ≥6 and who underwent two consecutive CT scans before and shortly after IV t-PA infusion were enrolled. Patients were classified into no, moderate, and marked expansion groups based on decreases in ASPECTS (0-1, 2-3, and ≥4, respectively) on follow-up CT. Collateral status was graded using CT angiography.

RESULTS

Of the 104 patients, 16 (15.4%) patients showed moderate and 13 (12.5%) patients showed marked infarct core expansion on follow-up CT scans obtained at 71.1±19.1 min after baseline CT scan. Sixteen (15.4%) patients had an ASPECTS value <6 on the follow-up CT. None of the patients with marked expansion were independent at 3 months. Univariate analysis and ordinal logistic regression analysis demonstrated that the infarct core expansion was significantly associated with collateral status (p<0.001).

CONCLUSION

Among patients who were considered for IAT after IV t-PA treatment, one out of every seven patients exhibited marked expansion of infarct core on follow-up CT before IAT. These patients tend to have poor collaterals and poor outcomes despite rescue IAT.

Imaging of Ischemic Stroke

PURPOSE OF REVIEW

This article provides an overview of cerebrovascular hemodynamics, acute stroke pathophysiology, and collateral circulation, which are pivotal in the modern imaging of ischemic stroke that guides the care of the patient with stroke.

RECENT FINDINGS

Neuroimaging provides extensive information on the brain and vascular health. Multimodal CT and MRI delineate the hemodynamics of ischemic stroke that may be used to guide treatment decisions and prognosticate regarding expected outcomes. Mismatch imaging with either CT or MRI may identify patients with salvageable regions who are at risk and likely to benefit from reperfusion therapy, even if they are outside the standard time window. Imaging of collateral circulation and determination of collateral grade may predict greater reperfusion, lower hemorrhage risk, and better functional outcome. Current neuroimaging technology also enables the identification of patients at high risk of hemorrhagic transformation or those who may be harmed by treatment or unlikely to benefit from it.

SUMMARY

This article reviews the use and impact of imaging for the patient with ischemic stroke, emphasizing how imaging builds upon clinical evaluation to establish diagnosis or etiology, reveal key pathophysiology, and guide therapeutic decisions.

Minds treating brains: understanding the interpretation of non-contrast CT ASPECTS in acute ischemic stroke

INTRODUCTION

The Alberta Stroke Program Early CT Score on non-contrast CT is a key component of prognostication and treatment selection in acute stroke care. Previous findings show that the reliability of this scale must be improved to maximize its clinical utility. Areas covered: This review discusses technical, patient-level, and reader-level sources of variability in ASPECTS reading; relevant concepts in the psychology of medical image perception; and potential interventions likely to improve inter- and intra-rater reliability. Expert commentary: Approaching variability in medical decision making from a psychological perspective will afford cognitively informed insights into the development of interventions and training techniques aimed at improving this issue.

The role of neuroimaging in elucidating the pathophysiology of cerebral ischemia

Neuroimaging provides detailed information regarding the hemodynamic, metabolic and cellular parameters of cerebral ischemia (CI). Although providing just a snapshot in time, it assists in delineating the boundaries and extent of this continually evolving process, from the irreversibly damaged infarct core to the penumbral tissue, where salvage via reperfusion has been the focus of acute stroke therapies. Beyond the extent of the ischemic lesion, neuroimaging elucidates the topography and underlying mechanism of CI. Finally, based on the pathophysiological information, neuroimaging assists in the selection of optimal therapeutic strategies, from hyperacute to chronic phases of CI. Here we review different neuroimaging techniques by which the pathophysiology of cerebral ischemia can be delineated. This article is part of the Special Issue entitled 'Cerebral Ischemia'.

Reliability, Reproducibility and Prognostic Accuracy of the Alberta Stroke Program Early CT Score on CT Perfusion and Non-Contrast CT in Hyperacute Stroke

Background: Alberta Stroke Program Early CT Score (ASPECTS) assesses early ischemic change on non-contrast CT (NCCT). We hypothesised that assessing ASPECTS regions on CT Perfusion (CTP) rather than NCCT would improve inter-rater agreement and prognostic accuracy, particularly in patients presenting early after stroke onset. Methods: Ischemic stroke patients treated with intravenous alteplase from 2009 to 2014 at our institution were included in this study. Inter-rater agreement and prognostic accuracy of ASPECTS across modalities were analysed by the time between stroke onset and initial NCCT, dichotomized 1st quartile versus quartiles 2-4, referred to as epochs. ASPECTS was assessed by 2 independent raters, blinded to stroke onset time, with agreement determined by weighted kappa (κw). Prognostic accuracy for favourable outcome (modified Rankin Scale 0-2) was assessed using the receiver-operating characteristic analysis. Results: A total of 227 participants were included. There was significant time-by-CT modality interaction for ASPECTS, p < 0.0001. The inter-rater agreement of ASPECTS on NCCT significantly increased as onset to CT time increased (κw epoch 1 = 0.76 vs. κw epoch 2-4 = 0.89, p = 0.04), whereas agreement using CTP parameters was stable across epochs. Inter-rater agreement for CTP-ASPECTS was significantly higher than NCCT in early epoch: Tmax κw = 0.96, p = 0.002; cerebral blood volume (CBV) κw = 0.95, p = 0.003; cerebral blood flow (CBF) κw = 0.94, p = 0.006, with no differences in the later epochs. Prognostic accuracy of ASPECTS on NCCT in epoch 1 were (area under the ROC curves [AUC] = 0.52, 95% CI 0.48-0.56), CBV (AUC = 0.55, 95% CI 0.42-0.69, CBF (AUC = 0.58, 95% CI 0.46-0.71) and Tmax (AUC = 0.62, 95% CI 0.49-0.75), p = 0.46 between modalities. Conclusions: CTP can improve reliability when assessing the extent of ischemic changes, particularly in patients imaged early after stroke onset.

CT Angiography ASPECTS Predicts Outcome Much Better Than Noncontrast CT in Patients with Stroke Treated Endovascularly

BACKGROUND AND PURPOSE

Noncontrast CT ASPECTS has been investigated as a predictor of outcome in patients with acute ischemic stroke. Our purpose was to investigate whether CTA source images are a better predictor of clinical and radiologic outcomes than NCCT ASPECTS in candidates for endovascular stroke therapy.

MATERIALS AND METHODS

CT scans of patients (n = 124) were independently evaluated by 2 readers for baseline NCCT and CTA source image ASPECTS and for follow-up ASPECTS. An mRS of ≤2 at 3 months was considered a favorable outcome. Receiver operating characteristic curve analysis was used to assess the ability of NCCT and CTA source image ASPECTS to identify patients with favorable outcomes. A stepwise multiple regression analysis was performed to find independent predictors of outcome.

RESULTS

Baseline CTA source image ASPECTS correlated better than NCCT ASPECTS with follow-up ASPECTS (r = 0.76 versus r = 0.51; P for comparison of the 2 coefficients < .001). Receiver operating characteristic curve analysis showed that baseline CTA source image ASPECTS compared with NCCT ASPECTS can better identify patients with favorable outcome (CTA source image area under the curve = 0.83; 95% CI, 0.76-0.91; NCCT area under the curve = 0.67; 95% CI, 0.58-0.77; P < .001). Finally, the stepwise regression analysis showed that lower age, good recanalization, lower time to recanalization, and good baseline CTA source image ASPECTS, not NCCT ASPECTS, were independent predictors of favorable outcome.

CONCLUSIONS

CTA source image ASPECTS predicts outcome better than NCCT ASPECTS; this finding suggests CTA rather than NCCT as a main step in the decision-making process for patients with acute ischemic stroke.

Validation of Serial Alberta Stroke Program Early CT Score as an Outcome Predictor in Thrombolyzed Stroke Patients

BACKGROUND

The Alberta Stroke Program Early CT Score (ASPECTS) on baseline imaging is an established predictor of functional outcome in anterior circulation acute ischemic stroke (AIS). We studied ASPECTS before intravenous thrombolysis (IVT) and at 24 hours to assess its prognostic value.

METHODS

Data for consecutive anterior circulation AIS patients treated with IVT from 2006 to 2013 were extracted from a prospectively managed registry at our tertiary center. Pre-thrombolysis and 24-hour ASPECTS were evaluated by 2 independent neuroradiologists. Outcome measures included symptomatic intracranial hemorrhage (SICH), modified Rankin Scale (mRS) at 90 days, and mortality. Unfavorable functional outcome was defined by mRS >1. Dramatic ASPECTS progression (DAP) was defined as deterioration in ASPECTS by 6 points or more.

RESULTS

Of 554 AIS patients thrombolyzed during the study period, 400 suffered from anterior circulation infarction. The median age was 65 years (interquartile range (IQR): 59-70) and the median National Institutes of Health Stroke Scale score was 18 points (IQR: 12-22). Compared with the pre-IVT ASPECTS (area under the curve [AUC] = .64, 95% confidence interval [CI]: .54-.65, P = .001), ASPECTS on the 24-hour CT scan (AUC = .78, 95% CI: .73-.82, P < .001), and change in ASPECTS (AUC = .69, 95% CI: .64-.74, P < .001) were better predictors of unfavorable functional outcome at 3 months. DAP, noted in 34 (14.4%) patients with good baseline ASPECTS (8-10 points), was significantly associated with unfavorable functional outcome (odds ratio [OR]: 9.91, 95% CI: 3.37-29.19, P ≤ .001), mortality (OR: 21.99, 95% CI: 7.98-60.58, P < .001), and SICH (OR: 8.57, 95% CI: 2.87-25.59, P < .001).

CONCLUSION

Compared with the pre-thrombolysis score, ASPECTS measured at 24 hours as well as serial change in ASPECTS is a better predictor of 3-month functional outcome.

Imaging of cerebral ischemic edema and neuronal death

PURPOSE

In acute cerebral ischemia, the assessment of irreversible injury is crucial for treatment decisions and the patient's prognosis. There is still uncertainty how imaging can safely differentiate reversible from irreversible ischemic brain tissue in the acute phase of stroke.

METHODS

We have searched PubMed and Google Scholar for experimental and clinical papers describing the pathology and pathophysiology of cerebral ischemia under controlled conditions.

RESULTS

Within the first 6 h of stroke onset, ischemic cell injury is subtle and hard to recognize under the microscope. Functional impairment is obvious, but can be induced by ischemic blood flow allowing recovery with flow restoration. The critical cerebral blood flow (CBF) threshold for irreversible injury is ~15 ml/100 g × min. Below this threshold, ischemic brain tissue takes up water in case of any residual capillary flow (ionic edema). Because tissue water content is linearly related to X-ray attenuation, computed tomography (CT) can detect and measure ionic edema and, thus, determine ischemic brain infarction. In contrast, diffusion-weighted magnetic resonance imaging (DWI) detects cytotoxic edema that develops at higher thresholds of ischemic CBF and is thus highly sensitive for milder levels of brain ischemia, but not specific for irreversible brain tissue injury.

CONCLUSION

CT and MRI are complimentary in the detection of ischemic stroke pathology and are valuable for treatment decisions.

Treatment of Acute Ischemic Stroke

PURPOSE OF REVIEW

This article provides an update on the state of the art of the emergency treatment of acute ischemic stroke with particular emphasis on the alternatives for reperfusion therapy.

RECENT FINDINGS

The results of several randomized controlled trials consistently and conclusively demonstrating that previously functional patients with disabling strokes from a proximal intracranial artery occlusion benefit from prompt recanalization with mechanical thrombectomy using a retrievable stent have changed the landscape of acute stroke therapy. Mechanical thrombectomy within 6 hours of symptom onset should now be considered the preferred treatment for these patients along with IV thrombolysis with recombinant tissue plasminogen activator (rtPA) within the first 4.5 hours for all patients who do not have contraindications for systemic thrombolysis. Patients who are ineligible for IV rtPA can also benefit from mechanical thrombectomy. Collateral status and time to reperfusion are the main determinants of outcome.

SUMMARY

Timely successful reperfusion is the most effective treatment for patients with acute ischemic stroke. Systems of care should be optimized to maximize the number of patients with acute ischemic stroke able to receive reperfusion therapy.

Alberta Stroke Program Early CT Score Infarct Location Predicts Outcome Following M2 Occlusion

Background

Although it is generally thought that patients with distal middle cerebral artery (M2) occlusion have a favorable outcome, it has previously been demonstrated that a substantial minority will have a poor outcome by 90 days. We sought to determine whether assessing the Alberta Stroke Program Early CT Score (ASPECTS) infarct location allows for identifying patients at risk for a poor 90-day outcome.

Methods

We retrospectively analyzed patients with isolated acute M2 occlusion admitted to a single academic center between January 2010 and August 2012. Infarct regions were defined according to ASPECTS system on the initial head computed tomography. Discriminant function analysis was used to define specific ASPECTS regions that are predictive of the 90-day functional outcome as defined as a modified Rankin Scale score of 3–6. In addition, logistic regression was used to model the relationship between each individual ASPECT region with poor outcome; for evaluation and comparison, odds ratios, c-statistics, and Akaike information criterion values were estimated for each region.

Results

Ninety patients with isolated M2 were included in the final analysis. ASPECTS score ≤6 predicted poor outcome in this cohort (sensitivity = 0.591, specificity = 0.838, p < 0.001). Using multiple approaches, we found that infarction in ASPECTS regions M3 and M6 were strongly associated with poor functional status by 90 days.

Conclusion

Infarction in ASPECTS regions M3 and M6 are key predictors of functional outcome following isolated distal M2 occlusion. These findings will be helpful in stratifying outcomes if validated in future studies.

Treatment of stroke with early imaging and revascularization: when to be aggressive?

Neuroimaging has a key role in the assessment and treatment of acute stroke. Cerebral computer tomography is the first step to differentiate hemorragic from ischemic stroke and to detect, in the latter, early signs representative of the lesion severity and predicting a possible hemorrhagic infarction after thrombolytic treatment.Advanced neuroimaging techniques are relevant in the assessment of the ischemic and/or hypo-perfused area, being an essential tool in uncertain situations or when the time of symptoms onset is unavailable, increasing the efficacy and safety of endovenous thrombolysis by enlarging its therapeutic window and leading to more accurate selection of patients to be treated.Moreover, advanced neuroimaging may be of help in choosing the patients to be submitted to endovascular treatment when occlusion of an intracranial artery is documented, either after intravenous thrombolysis or as a primary approach.Here we describe the impact of neuroimaging in the decisional process in acute ischemic stroke, presenting the literature evidence on the topic, especially regarding the recent trials on endovascular treatment.

Acute Ischemic Stroke Therapy Overview

The treatment of acute ischemic stroke has undergone dramatic changes recently subsequent to the demonstrated efficacy of intra-arterial (IA) device-based therapy in multiple trials. The selection of patients for both intravenous and IA therapy is based on timely imaging with either computed tomography or magnetic resonance imaging, and if IA therapy is considered noninvasive, angiography with one of these modalities is necessary to document a large-vessel occlusion amenable for intervention. More advanced computed tomography and magnetic resonance imaging studies are available that can be used to identify a small ischemic core and ischemic penumbra, and this information will contribute increasingly in treatment decisions as the therapeutic time window is lengthened. Intravenous thrombolysis with tissue-type plasminogen activator remains the mainstay of acute stroke therapy within the initial 4.5 hours after stroke onset, despite the lack of Food and Drug Administration approval in the 3- to 4.5-hour time window. In patients with proximal, large-vessel occlusions, IA device-based treatment should be initiated in patients with small/moderate-sized ischemic cores who can be treated within 6 hours of stroke onset. The organization and implementation of regional stroke care systems will be needed to treat as many eligible patients as expeditiously as possible. Novel treatment paradigms can be envisioned combining neuroprotection with IA device treatment to potentially increase the number of patients who can be treated despite long transport times and to ameliorate the consequences of reperfusion injury. Acute stroke treatment has entered a golden age, and many additional advances can be anticipated.

A Critical Review of Alberta Stroke Program Early CT Score for Evaluation of Acute Stroke Imaging

Assessment of ischemic stroke lesions on computed tomography (CT) or MRI using the Alberta Stroke Program Early CT Score (ASPECTS) is widely used to guide acute stroke treatment. We aimed to review the current evidence on ASPECTS. Originally, the score was developed for standardized lesion assessment on non-contrast CT (NCCT). Early studies described ASPECTS as a predictor of functional outcome and symptomatic intracranial hemorrhage after iv-thrombolysis with a threshold of ≤7 suggested to identify patients at high risk. Following studies rather pointed toward a linear relationship between ASPECTS and functional outcome. ASPECTS has also been applied to assess perfusion CT and diffusion-weighted MRI (DWI). Cerebral blood volume ASPECTS proved to be the best predictor of outcome, outperforming NCCT-ASPECTS in some studies. For DWI-ASPECTS varying thresholds to identify patients at risk for poor outcome were reported. ASPECTS has been used for patient selection in three of the five groundbreaking trials proving efficacy of mechanical thrombectomy published in 2015. ASPECTS values predict functional outcome after thrombectomy. Moreover, treatment effect of thrombectomy appears to depend on ASPECTS values being smaller or not present in low ASPECTS, while patients with ASPECTS 5–10 do clearly benefit from mechanical thrombectomy. However, as patients with low ASPECTS values were excluded from recent trials data on this subgroup is limited. There are several limitations to ASPECTS addressed in a growing number of studies. The score is limited to the anterior circulation, the template is unequally weighed and correlation with lesion volume depends on lesion location. Overall ASPECTS is a useful and easily applicable tool for assessment of prognosis in acute stroke treatment and to help guide acute treatment decisions regardless whether MRI or CT is used. Patients with low ASPECTS values are unlikely to achieve good outcome. However, methodological constraints of ASPECTS have to be considered, and based on present data, a clear cutoff value to define “low ASPECTS values” cannot be given.

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.

Severe cerebral hypovolemia on perfusion CT and lower body weight are associated with parenchymal haemorrhage after thrombolysis

INTRODUCTION

Haemorrhagic transformation of acute ischemic stroke (AIS) and particularly parenchymal haemorrhage (PH) remains a feared complication of intravenous thrombolysis (IVT). We aimed to identify clinical and perfusion CT (PCT) variables which are independently associated with PHs.

METHODS

In this observational cohort study, based on the Acute Stroke Registry Analysis of Lausanne (ASTRAL) from 2003 to December 2013, we selected patients with AIS involving the middle cerebral artery (MCA) territory who were thrombolysed within 4.5 h of symptoms' onset and who had a good quality baseline PCT at the beginning of IVT. In addition to demographic, clinical, laboratory and non-contrast CT data, volumes of salvageable tissue and ischemic core on PCT, as well as absolute CBF and CBV values within the ischemic regions were compared in patients with and without PH in multivariate analysis.

RESULTS

Of the 190 included patients, 24 (12.6%) presented a PH (11 had PH1 and 13 had PH2). In multivariate analysis of the clinical and radiological variables, the lowest CBV in the core and lower body weight was both significantly associated with PH (p = 0.009 and p = 0.024, respectively).

CONCLUSION

In thrombolysed MCA strokes, maximal hypoperfusion severity depicted by lowest CBV values in the core region and lower body weight are independently correlated with PH. This information, if confirmed in other case series, may add to the stratification of revascularisation decisions in patients with a perceived high PH risk.

Update on the effects of treatment with recombinant tissue-type plasminogen activator (rt-PA) in acute ischemic stroke

INTRODUCTION

Acute ischemic stroke (AIS) represents a major cause of death and disability all over the world. The recommended therapy aims at dissolving the clot to re-establish quickly the blood flow to the brain and reduce neuronal injury. Intravenous administration of recombinant tissue-type plasminogen activator (rt-PA) is clinically used with this goal.

AREAS COVERED

A description of beneficial and detrimental effects of rt-PA treatment is addressed. An overview of new therapies against AIS, such as new thrombolytics, sonolysis and sonothrombolysis, endovascular procedures, and association therapies is provided. Updates on the pathophysiological process leading to intracranial hemorrhage (ICH) is also discussed.

EXPERT OPINION

rt-PA treatment in AIS patients is beneficial to recovery outcomes. To weaken risks and improve benefits, it might be relevant to consider: i) a definitive identification of risk factors for symptomatic ICH; ii). a better organization of the health care system to reduce time-to-treatment and enhance discharge management. The pharmacological improvement of new thrombolytic drugs (such as tenecteplase and desmoteplase) targeting harmful and maximally exploiting beneficial effects might further reduce mortality and disability in AIS.

Good Intracranial Collaterals Trump Poor ASPECTS (Alberta Stroke Program Early CT Score) for Intravenous Thrombolysis in Anterior Circulation Acute Ischemic Stroke

BACKGROUND AND PURPOSE

In acute ischemic stroke, large early infarct size estimated by the Alberta Stroke Program Early CT Score (ASPECTS) is associated with poorer outcomes and is a relative contraindication for recanalization therapies. The state of the intracranial collateral circulation influences the functional outcome and may be a variable to consider before thrombolysis. We evaluated the prognostic effect of the collateral circulation in patients with thrombolyzed acute ischemic stroke who have large early infarct sizes as indicated by low ASPECTS.

MATERIALS AND METHODS

Patients with anterior circulation acute ischemic stroke who received a computed tomographic angiogram and subsequent treatment with intravenous tissue-type plasminogen activator from 2010 to 2013 were studied. Two independent neuroradiologists determined their ASPECTS. We stratified patients using ASPECTS into 2 groups: large volume infarcts (ASPECTS≤7 points) and small volume infarcts (ASPECTS 8-10). In addition, we evaluated a third group with very large volume infarcts (ASPECTS≤5 points). We then analyzed the 3 subgroups using the Maas, Tan, and ASPECTS-collaterals grading systems of the computed tomographic angiogram intracranial collaterals. Good outcomes were defined by modified Rankin Scale score of 0 to 2 at 3 months.

RESULTS

A total of 300 patients were included in the final analysis. For patients with very large volume infarcts (ASPECTS≤5 points), univariable analysis showed that younger age, male sex, lower National Institute of Health Stroke Scale (NIHSS), lower systolic blood pressure, and good collaterals by Maas, Tan, or ASPECTS-collaterals grading were predictors of good outcomes. On multivariate analysis, younger age (odds ratio, 0.93; 95% confidence interval, 0.89-0.97; P=0.002) and good collaterals by ASPECTS-collaterals system (odds ratio, 1.34; 95% confidence interval, 1.15-1.57; P<0.001) were associated with good outcomes.

CONCLUSIONS

In patients with large and very large volume infarcts, good collaterals as measured by the ASPECTS-collaterals system is associated with improved outcomes and can help select patients for intravenous thrombolysis.

CBV_ASPECTS Improvement over CT_ASPECTS on Determining Irreversible Ischemic Lesion Decreases over Time

The Alberta Stroke Program Early CT Score (ASPECTS) is a useful scoring system for assessing early ischemic signs on noncontrast computed tomography (CT). Cerebral blood volume (CBV) on CT perfusion defines the core lesion assumed to be irreversibly damaged. We aim to explore the advantages of CBV_ASPECTS over CT_ASPECTS in the prediction of final infarct volume according to time.

METHODS

Consecutive patients with anterior circulation stroke who underwent endovascular reperfusion according to initial CT_ASPECTS ≥7 were studied. CBV_ASPECTS was assessed blindly later on. Recanalization was defined as thrombolysis in cerebral ischemia score 2b-3. Final infarct volumes were measured on follow-up imaging. We compared ASPECTS on CBV and CT images, and defined ASPECTS agreement as: CT_ASPECTS - CBV_ASPECTS ≤1.

RESULTS

Sixty-five patients, with a mean age of 67 ± 14 years and a median National Institutes of Health Stroke Scale score of 16 (range 10-20), were studied. The recanalization rate was 78.5%. The median CT_ASPECTS was 9 (range 8-10), and the CBV_ASPECTS was 8 (range 8-10). The mean time from symptoms to CT was 219 ± 143 min. Fifty patients (76.9%) showed ASPECTS agreement. The ASPECTS difference was inversely correlated to the time from symptoms to CT (r = -0.36, p < 0.01). A ROC curve defined 120 min as the best cutoff point after which the ASPECTS difference becomes more frequently ≤1. After 120 min, 89.5% of the patients showed ASPECTS agreement (as compared with 37.5% for <120 min, p < 0.01). CBV_ASPECTS but not CT_ASPECTS correlated with final infarct (r = -0.33, p < 0.01). However, if CT was done >2 h after symptom onset, CT_ASPECTS also correlated to final infarct (r = -0.39, p = 0.01).

CONCLUSIONS

In acute stroke, CBV_ASPECTS correlates with the final infarct volume. However, when CT is performed after 120 min from symptom onset, CBV_ASPECTS does not add relevant information to CT_ASPECTS.

Evolving Treatments for Acute Ischemic Stroke

The purpose of this article is to review advances in stroke treatment in the hyperacute period. With recent evolutions of technology in the fields of imaging, thrombectomy devices, and emergency room workflow management, as well as improvement in statistical methods and study design, there have been ground breaking changes in the treatment of acute ischemic stroke. We describe how stroke presents as a clinical syndrome and how imaging as the most important biomarker will help differentiate between stroke subtypes and treatment eligibility. The evolution of hyperacute treatment has led to the current standard of care: intravenous thrombolysis with tissue-type plasminogen activator and endovascular treatment for proximal vessel occlusion in the anterior cerebral circulation. All patients with acute ischemic stroke are in need of hyperacute secondary prevention because the risk of recurrence is highest closest to the index event. The dominant themes of modern stroke care are the use of neurovascular imaging and speed of diagnosis and treatment.

Performance of CT ASPECTS and Collateral Score in Risk Stratification: Can Target Perfusion Profiles Be Predicted without Perfusion Imaging?

BACKGROUND AND PURPOSE

Endovascular trials suggest that revascularization benefits a subset of acute ischemic stroke patients with large-artery occlusion and small-core infarct volumes. The objective of our study was to identify thresholds of noncontrast CT-ASPECTS and collateral scores on CT angiography that best predict ischemic core volume thresholds quantified by CT perfusion among patients with acute ischemic stroke.

MATERIALS AND METHODS

Fifty-four patients with acute ischemic stroke (<12 hours) and MCA/intracranial ICA occlusion underwent NCCT/CTP during their initial evaluation. CTP analysis was performed on a user-independent platform (RApid processing of PerfusIon and Diffusion), computing core infarct (defined as CBF of <30% normal). A target mismatch profile consisting of infarction core of ≤50 mL was selected to define candidates with acute ischemic stroke likely to benefit from revascularization.

RESULTS

NCCT-ASPECTS of ≥9 with a CTA collateral score of 3 had 100% specificity for identifying patients with a CBF core volume of ≤50 mL. NCCT-ASPECTS of ≤6 had 100% specificity for identifying patients with a CBF core volume of >50 mL. In our cohort, 44 (81%) patients had an NCCT-ASPECTS of ≥9, a CTA collateral score of 3, or an NCCT-ASPECTS of ≤6.

CONCLUSIONS

Using an NCCT-ASPECTS of ≥9 or a CTA collateral score of 3 best predicts CBF core volume infarct of ≤50 mL, while an NCCT-ASPECTS of ≤6 best predicts a CBF core volume infarct of >50 mL. Together these thresholds suggest that a specific population of patients with acute ischemic stroke not meeting such profiles may benefit most from CTP imaging to determine candidacy for revascularization.

Scientific Rationale for the Inclusion and Exclusion Criteria for Intravenous Alteplase in Acute Ischemic Stroke

Purpose—

To critically review and evaluate the science behind individual eligibility criteria (indication/inclusion and contraindications/exclusion criteria) for intravenous recombinant tissue-type plasminogen activator (alteplase) treatment in acute ischemic stroke. This will allow us to better inform stroke providers of quantitative and qualitative risks associated with alteplase administration under selected commonly and uncommonly encountered clinical circumstances and to identify future research priorities concerning these eligibility criteria, which could potentially expand the safe and judicious use of alteplase and improve outcomes after stroke.

Methods—

Writing group members were nominated by the committee chair on the basis of their previous work in relevant topic areas and were approved by the American Heart Association Stroke Council’s Scientific Statement Oversight Committee and the American Heart Association’s Manuscript Oversight Committee. The writers used systematic literature reviews, references to published clinical and epidemiology studies, morbidity and mortality reports, clinical and public health guidelines, authoritative statements, personal files, and expert opinion to summarize existing evidence and to indicate gaps in current knowledge and, when appropriate, formulated recommendations using standard American Heart Association criteria. All members of the writing group had the opportunity to comment on and approved the final version of this document. The document underwent extensive American Heart Association internal peer review, Stroke Council Leadership review, and Scientific Statements Oversight Committee review before consideration and approval by the American Heart Association Science Advisory and Coordinating Committee.

Results—

After a review of the current literature, it was clearly evident that the levels of evidence supporting individual exclusion criteria for intravenous alteplase vary widely. Several exclusionary criteria have already undergone extensive scientific study such as the clear benefit of alteplase treatment in elderly stroke patients, those with severe stroke, those with diabetes mellitus and hyperglycemia, and those with minor early ischemic changes evident on computed tomography. Some exclusions such as recent intracranial surgery are likely based on common sense and sound judgment and are unlikely to ever be subjected to a randomized, clinical trial to evaluate safety. Most other contraindications or warnings range somewhere in between. However, the differential impact of each exclusion criterion varies not only with the evidence base behind it but also with the frequency of the exclusion within the stroke population, the probability of coexistence of multiple exclusion factors in a single patient, and the variation in practice among treating clinicians.

Cerebral Blood Volume ASPECTS Is the Best Predictor of Clinical Outcome in Acute Ischemic Stroke: A Retrospective, Combined Semi-Quantitative and Quantitative Assessment

Introduction

The capability of CT perfusion (CTP) Alberta Stroke Program Early CT Score (ASPECTS) to predict outcome and identify ischemia severity in acute ischemic stroke (AIS) patients is still questioned.

Methods

62 patients with AIS were imaged within 8 hours of symptom onset by non-contrast CT, CT angiography and CTP scans at admission and 24 hours. CTP ASPECTS was calculated on the affected hemisphere using cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) maps by subtracting 1 point for any abnormalities visually detected or measured within multiple cortical circular regions of interest according to previously established thresholds. MTT-CBV ASPECTS was considered as CTP ASPECTS mismatch. Hemorrhagic transformation (HT), recanalization status and reperfusion grade at 24 hours, final infarct volume at 7 days and modified Rankin scale (mRS) at 3 months after onset were recorded.

Results

Semi-quantitative and quantitative CTP ASPECTS were highly correlated (p<0.00001). CBF, CBV and MTT ASPECTS were higher in patients with no HT and mRS≤2 and inversely associated with final infarct volume and mRS (p values: from p<0.05 to p<0.00001). CTP ASPECTS mismatch was slightly associated with radiological and clinical outcomes (p values: from p<0.05 to p<0.02) only if evaluated quantitatively. A CBV ASPECTS of 9 was the optimal semi-quantitative value for predicting outcome.

Conclusions

Our findings suggest that visual inspection of CTP ASPECTS recognizes infarct and ischemic absolute values. Semi-quantitative CBV ASPECTS, but not CTP ASPECTS mismatch, represents a strong prognostic indicator, implying that core extent is the main determinant of outcome, irrespective of penumbra size.

CT angiography and CT perfusion improve prediction of infarct volume in patients with anterior circulation stroke

Introduction

We investigated whether baseline CT angiography (CTA) and CT perfusion (CTP) in acute ischemic stroke could improve prediction of infarct presence and infarct volume on follow-up imaging.

Methods

We analyzed 906 patients with suspected anterior circulation stroke from the prospective multicenter Dutch acute stroke study (DUST). All patients underwent baseline non-contrast CT, CTA, and CTP and follow-up non-contrast CT/MRI after 3 days. Multivariable regression models were developed including patient characteristics and non-contrast CT, and subsequently, CTA and CTP measures were added. The increase in area under the curve (AUC) and R² was assessed to determine the additional value of CTA and CTP.

Results

At follow-up, 612 patients (67.5 %) had a detectable infarct on CT/MRI; median infarct volume was 14.8 mL (interquartile range (IQR) 2.8–69.6). Regarding infarct presence, the AUC of 0.82 (95 % confidence interval (CI) 0.79–0.85) for patient characteristics and non-contrast CT was improved with addition of CTA measures (AUC 0.85 (95 % CI 0.82–0.87); p < 0.001) and was even higher after addition of CTP measures (AUC 0.89 (95 % CI 0.87–0.91); p < 0.001) and combined CTA/CTP measures (AUC 0.89 (95 % CI 0.87–0.91); p < 0.001). For infarct volume, adding combined CTA/CTP measures (R² = 0.58) was superior to patient characteristics and non-contrast CT alone (R² = 0.44) and to addition of CTA alone (R² = 0.55) or CTP alone (R² = 0.54; all p < 0.001).

Conclusion

In the acute stage, CTA and CTP have additional value over patient characteristics and non-contrast CT for predicting infarct presence and infarct volume on follow-up imaging. These findings could be applied for patient selection in future trials on ischemic stroke treatment.

Electronic supplementary material

The online version of this article (doi:10.1007/s00234-015-1636-z) contains supplementary material, which is available to authorized users.

Gray-Matter Volume Estimate Score: A Novel Semi-Automatic Method Measuring Early Ischemic Change on CT

Background and Purpose

We developed a novel method named Gray-matter Volume Estimate Score (GRAVES), measuring early ischemic changes on Computed Tomography (CT) semi-automatically by computer software. This study aimed to compare GRAVES and Alberta Stroke Program Early CT Score (ASPECTS) with regards to outcome prediction and inter-rater agreement.

Methods

This was a retrospective cohort study. Among consecutive patients with ischemic stroke in the anterior circulation who received intra-arterial therapy (IAT), those with a readable pretreatment CT were included. Two stroke neurologists independently measured both the GRAVES and ASPECTS. GRAVES was defined as the percentage of estimated hypodense lesion in the gray matter of the ipsilateral hemisphere. Spearman correlation analysis, receiver operating characteristic (ROC) comparison test, and intra-class correlation coefficient (ICC) comparison tests were performed between GRAVES and ASPECTS.

Results

Ninety-four subjects (age: 68.7±10.3; male: 54 [54.9%]) were enrolled. The mean GRAVES was 9.0±8.9 and the median ASPECTS was 8 (interquartile range, 6-9). Correlation between ASPECTS and GRAVES was good (Spearman’s rank correlation coefficient, 0.642; P<0.001). ROC comparison analysis showed that the predictive value of GRAVES for favorable outcome was not significantly different from that of ASPECTS (area under curve, 0.765 vs. 0.717; P=0.308). ICC comparison analysis revealed that inter-rater agreement of GRAVES was significantly better than that of ASPECTS (0.978 vs. 0.895; P<0.001).

Conclusions

GRAVES had a good correlation with ASPECTS. GRAVES was as good as ASPECTS in predicting a favorable clinical outcome, but was better than ASPECTS regarding inter-rater agreement. GRAVES may be used to predict the outcome of IAT.

A Combined Arterial and Venous Grading Scale to Predict Outcome in Anterior Circulation Ischemic Stroke

OBJECTIVE

Prognostic evaluation based on cortical vein score difference in stroke (PRECISE) score, a novel venous grading scale better predicted stroke outcomes. Henceforth, we aimed to describe and determine if a physiologically relevant combined arterial and venous grading scale (CRISP grading scale) is accurate in determining 90-day stroke outcomes in patients with proximal arterial occlusion in the anterior circulation.

METHODS

Data are from the Keimyung Stroke Registry. Consecutive patients with M1 middle cerebral artery (MCA) or terminal internal carotid artery (ICA) occlusion on CT-angiography (CTA) from May-2004 to July-2008 were included. The affected hemisphere 'four veins composite score' and 'arterial collaterals' were each graded 'good' and 'poor'. On the combined scale, a 'good' grade represented a 'good' score on both scales and a 'poor' grade represented a 'poor' score on both scales. The 'other two' combinations were graded 'intermediate.'

RESULTS

Eighty-one patients were included in the study. Dummy variable regression analysis demonstrated that poor outcome was commonly seen in the group with poor arterial and venous grades [OR(95%CI); 48 (8.24, 279.598); P < 0.00001] as opposed to poor arterial collaterals alone [OR(95%CI); 9.6(1.483,62.162); P = 0.018]. In multivariate analysis the CRISP grade [OR(95%CI); 2.638(1.192, 6.039), P = 0.017] and National Institutes of Health Stroke Scale [OR(95%CI);1.230(1.085, 1.395),P = 0.001(per unit increase)] emerged as the independent predictors of poor outcome (modified Rankin Scale >2) when adjusted for other imaging predictors of outcome.

CONCLUSION

CRISP grading was precise in predicting stroke outcomes when compared to individual imaging scales including arterial collateral grading, PRECISE score and CTA-SI ASPECTS in patients with proximal arterial occlusion in the anterior circulation.

Performance and Predictive Value of a User-Independent Platform for CT Perfusion Analysis: Threshold-Derived Automated Systems Outperform Examiner-Driven Approaches in Outcome Prediction of Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Treatment strategies in acute ischemic stroke aim to curtail ischemic progression. Emerging paradigms propose patient subselection using imaging biomarkers derived from CT, CTA, and CT perfusion. We evaluated the performance of a fully-automated computational tool, hypothesizing enhancements compared with qualitative approaches. The correlation between imaging variables and clinical outcomes in a cohort of patients with acute ischemic stroke is reported.

MATERIALS AND METHODS

Sixty-two patients with acute ischemic stroke and MCA or ICA occlusion undergoing multidetector CT, CTA, and CTP were retrospectively evaluated. CTP was processed on a fully operator-independent platform (RApid processing of PerfusIon and Diffusion [RAPID]) computing automated core estimates based on relative cerebral blood flow and relative cerebral blood volume and hypoperfused tissue volumes at varying thresholds of time-to-maximum. Qualitative analysis was assigned by 2 independent reviewers for each variable, including CT-ASPECTS, CBV-ASPECTS, CBF-ASPECTS, CTA collateral score, and CTA clot burden score. Performance as predictors of favorable clinical outcome and final infarct volume was established for each variable.

RESULTS

Both RAPID core estimates, CT-ASPECTS, CBV-ASPECTS, and clot burden score correlated with favorable clinical outcome (P < .05); CBF-ASPECTS and collateral score were not significantly associated with favorable outcome, while hypoperfusion estimates were variably associated, depending on the selected time-to-maximum thresholds. Receiver operating characteristic analysis demonstrated disparities among tested variables, with RAPID core and hypoperfusion estimates outperforming all qualitative approaches (area under the curve, relative CBV = 0.86, relative CBF = 0.81; P < .001).

CONCLUSIONS

Qualitative approaches to acute ischemic stroke imaging are subject to limitations due to their subjective nature and lack of physiologic information. These findings support the benefits of high-speed automated analysis, outperforming conventional methodologies while limiting delays in clinical management.

CT perfusion cerebral blood volume does not always predict infarct core in acute ischemic stroke

We investigated the practical clinical utility of the CT perfusion (CTP) cerebral blood volume (CBV) parameter for differentiating salvageable from non-salvageable tissue in acute ischemic stroke (AIS). Fifty-five patients with AIS were imaged within 6 h from onset using CTP. Admission CBV defect (CBVD) volume was outlined using previously established gray and white matter CBV thresholds for infarct core. Admission cerebral blood flow (CBF) hypoperfusion and CBF/CBV mismatch were visually evaluated. Truncation of the ischemic time-density curve (ITDC) and hypervolemia status at admission, recanalization at 24-h CT angiography, hemorrhagic transformation (HT) at 24 h and/or 7-day non-contrast CT (NCCT), final infarct volume as indicated by 3-month NCCT defect (NCCTD) and 3-month modified Rankin Score were determined. Patients with recanalization and no truncation had the highest correlation (R = 0.81) and regression slope (0.80) between CBVD and NCCTD. Regression slopes were close to zero for patients with admission hypervolemia with/without recanalization. Hypervolemia underestimated (p = 0.02), while recanalization and ITDC truncation overestimated (p = 0.03) the NCCTD. Among patients with confirmed recanalization at 24 h, 38 % patients had an admission CBF/CBV mismatch within normal appearing areas on respective NCCT. 83 % of these patients developed infarction in admission hypervolemic CBF/CBV mismatch tissue. A reduction in CBV is a valuable predictor of infarct core when the acquisition of ITDC data is complete and hypervolemia is absent within the tissue destined to infarct. Raised or normal CBV is not always indicative of salvageable tissue, contrary to the current definition of penumbra.

Aspects correlates with Scandinavian Stroke Scale for predicting early neurological impairment

OBJECTIVE

To investigate the correlation between the Alberta Program Early CT Score (ASPECTS) and the Scandinavian Stroke Scale (SSS) for the evaluation of neurological impairment in patients with acute stroke.

METHOD

59 patients with a first acute ischemic stroke were evaluated. The ASPECTS were evaluated by 2 neurologists at admission and by another neurologist after 48 hours. The NIHSS and SSS was applied to determinate stroke severity. Correlations and agreements were analysed statistically by Spearman and Kappa tests.

RESULTS

ASPECTS was correlated with National Institute of Health Stroke Scale (NIHSS) at admission (r = -0.52; p < 0.001) and SSS (r = 0.50; p < 0.001). The ASPECTS and SSS items were most correlated with arm (r = 0.52; p < 0.001) and hand (r = 0.49; p < 0.001) motor power, and speech (r = 0.51; p < 0.001). The SSS of 25.5 shows sensitivity (68%) and specificity (72%) when associated with ASPECTS ≤ 7.

CONCLUSION

The SSS can predict worst neurological impairment when associated with lower values of ASPECTS.

Value of Utilizing Both Aspects and CT Angiography Collateral Score for Outcome Prediction in Acute Ischemic Stroke

Background

Alberta Stroke Program Early CT Score (ASPECTS) represents the extent of irreversibly damaged tissue; while CT angiography collateral score (CTA-CS) denotes the degree of collaterals.

Aims

We investigated whether there is cumulative value in using both ASPECTS and CTA-CS for outcome prediction and attempted to determine the specific subgroup of patients who could benefit from successful reperfusion using these scores.

Methods

This is a retrospective observational study of stroke patients treated with intra-arterial reperfusion therapy for unilateral arterial occlusion in the anterior circulation. A favorable outcome was defined as modified Rankin Scale ≤ 2 at three-months. Receiver operating characteristic comparison analysis was performed to decide whether outcome predictability increases when ASPECTS and CTA-CS are used together. Classification and regression tree (CART) analysis was done to identify the variables that best predict outcome and define the specific subgroup of patients who could benefit from successful reperfusion.

Results

A total of 91 consecutive patients were included. Outcome predictability of ASPECTS with CTA-CS was better than that of ASPECTS ( P = 0·088) or that of CTA-CS ( P = 0·049). CART analysis revealed that ASPECTS > 5 was the primary determinant of favorable outcome, followed by CTA-CS > 1. Among 19 patients with ASPECTS ≤ 5, none had a favorable outcome. Successful reperfusion was associated significantly with favorable outcome in the 51 patients with ASPECTS > 5 and CTA-CS > 1, but not in the 21 patients with ASPECTS > 5 and CTA-CS ≤ 1.

Conclusions

Outcome predictability improves when using ASPECTS and CTA-CS together.

Impact of temporary opening using a stent retriever on clinical outcome in acute ischemic stroke

Background

Stent retriever has a distinct ability to restore blood flow temporarily before achieving final reperfusion. There has been a limited report regarding the clinical impact of it. We investigated if temporary opening of occluded vessels using a stent retriever before final reperfusion might improve clinical outcome in acute ischemic stroke patients who received the endovascular reperfusion treatment.

Methods

We enrolled consecutive ischemic stroke patients who had an initial occlusive lesion in the anterior circulation and achieved final reperfusion (Thrombolysis In Cerebral Infarction [TICI] ≥2) by endovascular treatment. Temporary opening was defined as the presence of ante grade flow (TICI≥2) during deployment of a stent retriever. Favorable outcome was defined as a modified Rankin scale score≤2 at 90 day.

Results

A total of 98 patients were included in the study and temporary opening was achieved in 49 (50%). Temporary opening was associated with favorable outcome (odds ratio, 7.825; 95% confidence interval, 1.592–38.461; p = 0.011) in the multivariate analysis. The probability of having a favorable outcome tended to decrease as time from onset to final reperfusion increased in patients without temporary opening. However, this trend was not evident in the patient with temporary opening. The beneficial effect of temporary opening on clinical outcome seemed to be present in patients with good collaterals but not in patients with poor collaterals.

Conclusions

Temporary opening of occluded vessel using a stent retriever may be beneficial for improving clinical outcome in acute ischemic stroke patients.

Telemedical Brain Computed Tomography Misinterpretation by Stroke Neurologists Is Not Associated with Thrombolysis-Related Intracranial Hemorrhage

BACKGROUND

The Stroke Eastern Saxony Network (SOS-NET) provides telecare for acute stroke patients. Stroke neurologists recommend intravenous thrombolysis based on clinical assessment and cerebral computed tomography (CT) evaluation using Alberta Stroke Program Early CT score (ASPECTS). We sought to assess whether ASPECTS misinterpretation by stroke neurologists was associated with thrombolysis-related symptomatic intracranial hemorrhage (sICH).

METHODS

We retrospectively analyzed consecutive SOS-NET patients treated with thrombolytics from July 2007 to July 2012. Experienced neuroradiologists re-evaluated CT scans blinded to clinical information providing reference standard. We defined ASPECTS underestimation as ASPECTS stroke neurologist--ASPECTS neuroradiologist more than 1 point. Primary outcome was sICH by European Cooperative Acute Stroke Study II criteria. Secondary outcome was unfavorable outcome at discharge defined as modified Rankin Scale scores 3 or more.

RESULTS

Of 1659 patients with acute ischemic stroke, thrombolysis was performed in 657 patients. Complete primary outcome and imaging data were available for 432 patients (median age, 75; interquartile range [IQR], 12 years; National Institutes of Health Stroke Scale score, 12 [IQR, 11]; 52.8% women). Nineteen patients (4.4%) had sICH, and 259 patients (60.0%) had an unfavorable outcome at discharge. Interobserver agreement between ASPECTS assessment was fair (κ = .51). ASPECTS underestimation was neither associated with sICH (adjusted odds ratio (OR), 1.32; 95% confidence interval (CI), .36-4.83, P = .68) nor unfavorable outcome (adjusted OR, 1.10; 95% CI, .47-2.54; P = .83).

CONCLUSIONS

Despite fair interrater agreement between stroke neurologists and expert neuroradiologists, underestimation of ASPECTS by the former was not associated with thrombolysis-related sICH in our telestroke network.

Randomized assessment of rapid endovascular treatment of ischemic stroke

BACKGROUND

Among patients with a proximal vessel occlusion in the anterior circulation, 60 to 80% of patients die within 90 days after stroke onset or do not regain functional independence despite alteplase treatment. We evaluated rapid endovascular treatment in addition to standard care in patients with acute ischemic stroke with a small infarct core, a proximal intracranial arterial occlusion, and moderate-to-good collateral circulation.

METHODS

We randomly assigned participants to receive standard care (control group) or standard care plus endovascular treatment with the use of available thrombectomy devices (intervention group). Patients with a proximal intracranial occlusion in the anterior circulation were included up to 12 hours after symptom onset. Patients with a large infarct core or poor collateral circulation on computed tomography (CT) and CT angiography were excluded. Workflow times were measured against predetermined targets. The primary outcome was the score on the modified Rankin scale (range, 0 [no symptoms] to 6 [death]) at 90 days. A proportional odds model was used to calculate the common odds ratio as a measure of the likelihood that the intervention would lead to lower scores on the modified Rankin scale than would control care (shift analysis).

RESULTS

The trial was stopped early because of efficacy. At 22 centers worldwide, 316 participants were enrolled, of whom 238 received intravenous alteplase (120 in the intervention group and 118 in the control group). In the intervention group, the median time from study CT of the head to first reperfusion was 84 minutes. The rate of functional independence (90-day modified Rankin score of 0 to 2) was increased with the intervention (53.0%, vs. 29.3% in the control group; P<0.001). The primary outcome favored the intervention (common odds ratio, 2.6; 95% confidence interval, 1.7 to 3.8; P<0.001), and the intervention was associated with reduced mortality (10.4%, vs. 19.0% in the control group; P=0.04). Symptomatic intracerebral hemorrhage occurred in 3.6% of participants in intervention group and 2.7% of participants in control group (P=0.75).

CONCLUSIONS

Among patients with acute ischemic stroke with a proximal vessel occlusion, a small infarct core, and moderate-to-good collateral circulation, rapid endovascular treatment improved functional outcomes and reduced mortality. (Funded by Covidien and others; ESCAPE ClinicalTrials.gov number, NCT01778335.).

Imaging-based management of acute ischemic stroke patients: current neuroradiological perspectives

Advances in imaging-based management of acute ischemic stroke now provide crucial information such as infarct core, ischemic penumbra/degree of collaterals, vessel occlusion, and thrombus that helps in the selection of the best candidates for reperfusion therapy. It also predicts thrombolytic efficacy and benefit or potential hazards from therapy. Thus, radiologists should be familiar with various imaging studies for patients with acute ischemic stroke and the applicability to clinical trials. This helps radiologists to obtain optimal rapid imaging as well as its accurate interpretation. This review is focused on imaging studies for acute ischemic stroke, including their roles in recent clinical trials and some guidelines to optimal interpretation.

Computed tomography angiography source images closely reflect the integrity of collateral circulation

BACKGROUND

We studied the interplay between collateral circulation, the location of the thrombus and infarct extent based on evaluation of CT angiography source images (CTA-SI) in predicting the clinical outcome of patients treated with intravenous thrombolytic therapy (<3h) in a retrospective cohort.

METHODS

Anterior circulation occlusion was detected with CTA in 105 patients. The site of the occlusion was recorded, collaterals were assessed with Collateral Score (CS) and Alberta Stroke Program Early CT Score (ASPECTS) was evaluated from CTA-SI, and entered into logistic regression analysis to predict favorable clinical outcome (three-month modified Rankin Scale 0-2).

RESULTS

CTA-SI ASPECTS was highly correlated with CS (Spearman's rho=0.63, P=0.01). Not a single patient with good collaterals (CS 2-4) had a poor CTA-SI scan (ASPECTS 0-7). The mean CTA-SI ASPECTS score became progressively lower when the status of the collateral circulation deteriorated (ANOVA P<0.001). In univariate analysis a good CTA-SI scan at the admission predicted favorable three-month outcome (P<0.001). In a multivariate model containing CTA-SI ASPECTS, CS and the site of the occlusion along with significant clinical parameters, CTA-SI ASPECTS was rendered non-significant (P=0.43) in the presence of CS.

CONCLUSIONS

CTA-SI and CS convey overlapping information. CTA-SI is not a significant predictor of the clinical outcome three months after intravenous thrombolysis when the other CTA-based parameters, CS and the clot location, are considered simultaneously. CTA-SI may have a role in the assessment of the extent of irreversible ischemic changes at admission if contrast injection and image acquisition protocols are designed suitably.

Multimodal Computed Tomography Based Definition of Cerebral Imaging Profiles for Acute Stroke Reperfusion Therapy (CT-DEFINE): Results of a Prospective Observational Study

PURPOSE

To prospectively evaluate the prognostic impact of multimodal computed tomography-based imaging in ischemic stroke patients potentially eligible for reperfusion therapy.

METHODS

Anterior circulation stroke patients underwent non-contrast CT (NCCT), CT-angiography, and CT-perfusion within 12 h from symptom-onset. Patients could be treated with intravenous-tissue plasminogen activator (IV-tPA), endovascular or combined reperfusion therapies. Cerebral imaging profiles (IP) were NCCT-Alberta Stroke Program Early CT Score (ASPECTS) > 7 (IP1); NCCT-ASPECTS > 5 and proximal occlusion on CT-angiography (IP2); CT-perfusion mismatch between cerebral blood volume (CBV)-ASPECTS, and cerebral blood flow (CBF)-ASPECTS ≥ 2 (IP3). Favorable outcome was defined as modified Rankin Scale ≤ 2 at 3 months.

RESULTS

Of 102 included patients, 62 (61%) received any reperfusion therapy. In IP2 and IP3, favorable outcome was more frequent in patients with reperfusion therapy than in those without; however, this did not reach statistical significance (IP2: 39% vs 15%, p = 0.26; IP3: 50% vs 17 %; p = 0.31). No difference was seen in IP1 (58% vs 58%, p = 1.0). In IP2, patients with IV-tPA alone achieved better functional outcome (50% vs 11%, p = 0.03) and lower mortality (0% vs 28%, p = 0.045) than those without.

CONCLUSIONS

Our results suggest a benefit with imaging profile selection based upon the combination of a small-to-moderate-sized infarction and a visible intracranial occlusion in patients receiving IV-tPA. Reperfusion therapy may be futile in patients without proven vessel occlusion.

[Vascular assessment in stroke codes: role of computed tomography angiography]

Advances in imaging studies for acute ischemic stroke are largely due to the development of new efficacious treatments carried out in the acute phase. Together with computed tomography (CT) perfusion studies, CT angiography facilitates the selection of patients who are likely to benefit from appropriate early treatment. CT angiography plays an important role in the workup for acute ischemic stroke because it makes it possible to confirm vascular occlusion, assess the collateral circulation, and obtain an arterial map that is very useful for planning endovascular treatment. In this review about CT angiography, we discuss the main technical characteristics, emphasizing the usefulness of the technique in making the right diagnosis and improving treatment strategies.