Multimodal CT-assisted thrombolysis in patients with acute stroke: a cohort study

Contrast Staining in Noninfarcted Tissue after Endovascular Treatment of Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Contrast staining is a common finding after endovascular treatment of acute ischemic stroke. It typically occurs in infarcted tissue and is considered an indicator of irreversible brain damage. Contrast staining in noninfarcted tissue has not been systematically investigated. We sought to assess the incidence, risk factors, and clinical significance of contrast staining in noninfarcted tissue after endovascular treatment.

MATERIALS AND METHODS

We conducted a retrospective review of consecutive patients who underwent endovascular treatment for anterior circulation large-vessel occlusion acute ischemic stroke. Contrast staining, defined as new hyperdensity on CT after endovascular treatment, was categorized as either contrast staining in infarcted tissue if the stained region demonstrated restricted diffusion on follow-up MR imaging or contrast staining in noninfarcted tissue if the stained region demonstrated no restricted diffusion. Baseline differences between patients with and without contrast staining in noninfarcted tissue were compared. Logistic regression was used to identify independent associations for contrast staining in noninfarcted tissue after endovascular treatment.

RESULTS

Among 194 patients who underwent endovascular treatment for large-vessel occlusion acute ischemic stroke and met the inclusion criteria, contrast staining in infarcted tissue was noted in 52/194 (26.8%) patients; contrast staining in noninfarcted tissue, in 26 (13.4%) patients. Both contrast staining in infarcted tissue and contrast staining in noninfarcted tissue were noted in 5.6% (11/194). Patients with contrast staining in noninfarcted tissue were found to have a higher likelihood of having an ASPECTS of 8-10, to be associated with contrast staining in infarcted tissue, and to achieve successful reperfusion compared with those without contrast staining in noninfarcted tissue. In contrast staining in noninfarcted tissue regions, the average attenuation was 40 HU, significantly lower than the contrast staining in infarcted tissue regions (53 HU). None of the patients with contrast staining in noninfarcted tissue had clinical worsening during their hospital stay. The median discharge mRS was significantly lower in patients with contrast staining in noninfarcted tissue than in those without (3 versus 4; P = .018). No independent predictors of contrast staining in noninfarcted tissue were found.

CONCLUSIONS

Contrast staining can be seen outside the infarcted tissue after endovascular treatment of acute ischemic stroke, likely attributable to the reversible disruption of the BBB in ischemic but not infarcted tissue. While generally benign, understanding its characteristics is important because it may mimic pathologic conditions such as infarcted tissue and cerebral edema.

Controversies in Imaging of Patients with Acute Ischemic Stroke: AJR Expert Panel Narrative Review

The development of reperfusion therapies has profoundly impacted stroke care, initially with the advent of IV thrombolytic (IVT) treatment and, more recently, with the development and refinement of endovascular treatment (EVT). Progress in neuroimaging has supported the paradigm shift of stroke care, and advanced neuroimaging now has a fundamental role in triaging patients for both IVT and EVT. As the standard of care for acute ischemic stroke (AIS) evolves, controversies remain in certain clinical scenarios. This article explores the use of multimodality imaging for treatment selection of AIS in the context of recent guidelines, highlighting controversial topics and providing guidance for clinical practice. Results of major randomized trials supporting EVT are reviewed. Advantages and disadvantages of CT, CTA, MRI, and MRA in stroke diagnosis are summarized, with attention to level 1 evidence supporting the role of vascular imaging and perfusion imaging. Patient selection is compared between approaches based on time thresholds and physiologic approaches based on infarct core measurement using imaging. Moreover, various imaging approaches to core measurement are described. As ongoing studies push treatment boundaries, advanced imaging is expected to help identify a widening range of patients who may benefit from therapy.

CTP-guided reperfusion therapy in acute ischemic stroke: a meta-analysis

BACKGROUND

Computed tomography perfusion (CTP) imaging could be useful in guiding reperfusion therapy or patient selection in acute ischemic stroke (AIS) patients. The aim of the current study was to determine the efficacy of the CTP-guided reperfusion therapy in AIS by performing a systematic review and meta-analysis.

METHODS

Medline/PubMed, Embase, and the Cochrane library were searched using the terms: "CT perfusion", "acute stroke" and "reperfusion therapy". The following studies were included: (a) studies reporting original data; (b) patients aged 18 years or above; (c) patients diagnosed with anterior circulation AIS; and (d) studies with good methodological design.

RESULTS

Twenty-two studies were finally included in the metanalysis with a total of 5, 687 patients. CTP-guided reperfusion therapy was associated with increased odds of good functional outcome without significant difference in safety profile.

CONCLUSIONS

CTP-guided reperfusion therapy improved functional outcomes in AIS, with increased benefits to patients treated with endovascular thrombectomy.

Carotid stent occlusion after emergent stenting in acute ischemic stroke: Incidence, predictors and clinical relevance

BACKGROUND AND AIMS

Emergent stent placement may be required during neurothrombectomy. Our aim was to investigate the incidence, predictors and clinical relevance of early extracranial carotid stent occlusion following neurothrombectomy.

METHODS

We retrospectively analyzed a cohort of 761 consecutive neurothrombectomies performed at our center between May 2010 and August 2018, from whom a total of 106 patients had acute internal carotid artery occlusions. Early stent occlusion was defined as complete vessel occlusion within 24 h of neurothrombectomy. Clinical outcome was evaluated at day 90 with the modified Rankin Score scale (mRS). Pretreatment, procedural and outcome variables were recorded and analyzed using logistic regression.

RESULTS

Carotid stenting was performed in 99 (13%) patients. Of those, 22 (22%) had early stent occlusion at follow-up. Stent occlusion was associated with a lower use of post-stenting angioplasty [adjusted OR (aOR) = 11.2, 95%CI = 2.49-50.78, p = 0.002)], increased residual intrastent stenosis (aOR = 2.1, 95%CI = 1.38-3.06, p < 0.001) and unsuccesful intracranial recanalization (modified TICI score 0-2a) (aOR = 13.5, 95%CI = 1.97-92.24, p = 0.008). Stent occlusion was associated with poor clinical outcome at day 90 (poorer mRS shift, aOR = 3.9, 95%CI = 1.3-11.3, p = 0.014; mRS>2, aOR = 6.3, 95%CI = 1.8-22.7, p = 0.005), and with an increased rate of symptomatic intracranial hemorrhage at 24 h (14% versus 1%, p = 0.033).

CONCLUSIONS

Early carotid stent occlusion occurred in one out of five neurothrombectomies and was associated with periprocedural factors that included increased residual intrastent stenosis, a lower use of post-stenting angioplasty and unsuccessful intracranial recanalization. Further investigation is warranted for the evaluation of strategies aimed to prevent carotid stent occlusion.

Evaluating the Prognosis of Ischemic Stroke Using Low-Dose Multimodal Computed Tomography Parameters in Hyperacute Phase

PURPOSE

The aim of this study was to evaluate the potential value of low-dose multimodal computed tomography (CT) in predicting prognosis of acute ischemic stroke (AIS) within 6 hours.

METHODS

The admission "one-stop-shop" multimodal CT examination, including noncontrast CT (NCCT), low-dose CT perfusion, and CT angiography (CTA), was performed in patients with symptoms of stroke within 6 hours. Noncontrast CT, CTA source image (CTA-SI), cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP), and mean transit time (MTT) maps were studied using Alberta Stroke Program Early CT Score (ASPECTS). The regional leptomeningeal collateral (rLMC) score (0-20) was dichotomized into 2 groups: good (11-20) and poor (0-10) rLMC. Poor functional outcomes were defined by a modified Rankin scale score of 3 to 6.

RESULTS

One hundred forty-four patients were ultimately selected; 43.8% of them showed poor functional outcomes. They had lower ASPECTSs on NCCT, CTA-SI, CBV, CBF, TTP, and MTT, and poor rLMC was more frequently associated with poor functional outcomes (all P < 0.001). In the multivariate analysis for AIS patients with conservative treatment, CTA-SI-ASPECTS 6 or less (odds ratio [OR], 5.9; 95% confidence interval [95% CI], 1.9-18.4; P = 0.002) and poor collaterals (OR, 5.0; 95% CI, 1.3-15.4; P = 0.017), CBV-ASPECTS 6 or less (OR, 8.0; 95% CI, 2.7-24.0; P < 0.001), CBF-ASPECTS 4 or less (OR, 8.0; 95% CI, 2.0-31.5; P = 0.003), MTT-ASPECTS≤3 (OR, 5.8; 95% CI, 1.8-18.1; P = 0.003), TTP-ASPECTS 4 or less (OR, 5.0; 95% CI, 1.6-15.1; P = 0.005), and NCCT-ASPECTS 8 or less (OR, 5.9; 95% CI, 1.7-20.4; P = 0.005) were significantly associated with poor functional outcome. In the multivariate analysis for AIS patients with thrombolysis, CTA-SI-ASPECTS 6 or less (OR, 27.5; 95% CI, 2.9-262.3; P = 0.004), poor collaterals (OR, 28.0; 95% CI, 2.8-283.0; P < 0.028), and CBV-ASPECTS 6 or less (OR, 18.0; 95% CI, 3.0-107.7; P = 0.002) were associated with poor functional outcomes. Furthermore, the area under the curve (AUC) of the combination of CTA-SI-ASPECTS 6 or less, poor collaterals, and CBV-ASPECTS 6 or less (AUC, 0.87) was greater than that for any single parameter alone: CTA-SI-ASPECTS 6 or less (AUC, 0.80; P < 0.001), poor collaterals (AUC, 0.76; P < 0.001), and CBV-ASPECTS 6 or less (AUC, 0.81; P = 0.002).

CONCLUSIONS

The combination of CTA-SI-ASPECTS, collaterals, and CBV-ASPECTS may improve predictive power compared with a single parameter alone.

Penumbra and re-canalization acute computed tomography in ischemic stroke evaluation: PRACTISE study protocol

Rationale Multimodal imaging, including computed tomography angiography and computed tomography perfusion imaging, yields additional information on intracranial vessels and brain perfusion and can differentiate between ischemic core and penumbra which may affect patient selection for intravenous thrombolysis. Hypothesis The use of multimodal imaging will increase the number of patients receiving intravenous thrombolysis and lead to better treatment outcomes. Sample size 400 patients. Methods and design PRACTISE is a prospective, multicenter, randomized, controlled trial in which patients presenting within 4.5 h of symptom onset are randomized to either the current evidence-based imaging (NCCT alone) or additional multimodal computed tomography imaging (NCCT + computed tomography angiography + computed tomography perfusion). Clinical decisions on intravenous recombinant tissue plasminogen activator are documented. Total imaging time in both arms and time to initiation of treatment delivery in those treated with intravenous recombinant tissue plasminogen activator, is recorded. Follow-up will include brain imaging at 24 h to document infarct size, the presence of edema and the presence of intra-cerebral hemorrhage. Clinical evaluations include NIHSS score at baseline, 24 h and day 7 ± 2, and mRS at day 90 to define functional outcomes. Study outcomes The primary outcome is the proportion of patients receiving intravenous recombinant tissue plasminogen activator. Secondary end-points evaluate times to decision-making, comparison of different image processing software and clinical outcomes at three months. Discussion Multimodal computed tomography is a widely available tool for patient selection for revascularization therapy, but it is currently unknown whether the use of additional imaging in all stroke patients is beneficial. The study opened for recruitment in March 2015 and will provide data on the value of multimodal imaging in treatment decisions for acute stroke.

Site and Rate of Occlusive Disease in Cervicocerebral Arteries: A CT Angiography Study of 2209 Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE

CTA can rapidly and accurately detect and localize occlusive disease in patients with ischemic stroke. We have used CTA to assess arterial stenosis and occlusion in an ischemic stroke population arriving at a tertiary stroke center within 24 hours of symptom onset in order to obtain a comprehensive picture of occlusive disease pattern, and to determine the proportion of eligible candidates for endovascular treatment.

MATERIALS AND METHODS

Data from consecutive patients with acute ischemic stroke admitted to a single center between 2003 and 2012, collected in the Acute Stroke Registry and Analysis of Lausanne data base, were retrospectively analyzed. Patients with a diagnostic CTA within 24 hours of symptom onset were selected. Relevant extra- and intracranial pathology, defined as stenosis of ≥50% and occlusions, were registered and classified into 21 prespecified segments.

RESULTS

Of the 2209 included patients (42.1% women; median age, 72 years), 1075 (48.7%) had pathology in and 308 (13.9%) had pathology outside the ischemic territory. In the 50,807 arterial segments available for revision, 1851 (3.6%) abnormal segments were in the ischemic (symptomatic) territory and another 408 (0.8%) were outside it (asymptomatic). In the 1211 patients with ischemic stroke imaged within 6 hours of symptom onset, 40.7% had symptomatic large, proximal occlusions potentially amenable to endovascular therapy.

CONCLUSIONS

CTA in patients with acute ischemic stroke shows large individual variations of occlusion sites and degrees. Approximately half of such patients have no visible occlusive disease, and 40% imaged within 6 hours show large, proximal segment occlusions amenable to endovascular therapy. These findings show the importance of early noninvasive imaging of extra- and intracranial arteries for identifying occlusive disease, planning recanalization strategies, and designing interventional trials.

Perfusion CT in acute stroke: effectiveness of automatically-generated colour maps

OBJECTIVE

To evaluate the accuracy of perfusion CT (pCT) in the definition of the infarcted core and the penumbra, comparing the data obtained from the evaluation of parametric maps [cerebral blood volume (CBV), cerebral blood flow (CBF) and mean transit time (MTT)] with software-generated colour maps.

METHODS

A retrospective analysis was performed to identify patients with suspected acute ischaemic strokes and who had undergone unenhanced CT and pCT carried out within 4.5 h from the onset of the symptoms. A qualitative evaluation of the CBV, CBF and MTT maps was performed, followed by an analysis of the colour maps automatically generated by the software.

RESULTS

26 patients were identified, but a direct CT follow-up was performed only on 19 patients after 24-48 h. In the qualitative analysis, 14 patients showed perfusion abnormalities. Specifically, 29 perfusion deficit areas were detected, of which 15 areas suggested the penumbra and the remaining 14 areas suggested the infarct. As for automatically software-generated maps, 12 patients showed perfusion abnormalities. 25 perfusion deficit areas were identified, 15 areas of which suggested the penumbra and the other 10 areas the infarct. The McNemar's test showed no statistically significant difference between the two methods of evaluation in highlighting infarcted areas proved later at CT follow-up.

CONCLUSION

We demonstrated how pCT provides good diagnostic accuracy in the identification of acute ischaemic lesions. The limits of identification of the lesions mainly lie at the pons level and in the basal ganglia area. Qualitative analysis has proven to be more efficient in identification of perfusion lesions in comparison with software-generated maps. However, software-generated maps have proven to be very useful in the emergency setting. Advances in knowledge: The use of CT perfusion is requested in increasingly more patients in order to optimize the treatment, thanks also to the technological evolution of CT, which now allows a whole-brain study. The need for performing CT perfusion study also in the emergency setting could represent a problem for physicians who are not used to interpreting the parametric maps (CBV, MTT etc.). The software-generated maps could be of value in these settings, helping the less expert physician in the differentiation between different areas.

Computed tomography perfusion and computed tomography angiography for prediction of clinical outcomes in ischemic stroke patients after thrombolysis

Cerebral blood perfusion and cerebrovascular lesions are important factors that can affect the therapeutic efficacy of thrombolysis. At present, the majority of studies focus on assessing the accuracy of lesion location using imaging methods before treatment, with less attention to predictions of outcomes after thrombolysis. Thus, in the present study, we assessed the efficacy of combined computed tomography (CT) perfusion and CT angiography in predicting clinical outcomes after thrombolysis in ischemic stroke patients. The study included 52 patients who received both CT perfusion and CT angiography. Patients were grouped based on the following criteria to compare clinical outcomes: (1) thrombolytic and non-thrombolytic patients, (2) thrombolytic patients with CT angiography showing the presence or absence of a vascular stenosis, (3) thrombolytic patients with CT perfusion showing the presence or absence of hemodynamic mismatch, and (4) different CT angiography and CT perfusion results. Short-term outcome was assessed by the 24-hour National Institution of Health Stroke Scale score change. Long-term outcome was assessed by the 3-month modified Rankin Scale score. Of 52 ischemic stroke patients, 29 were treated with thrombolysis and exhibited improved short-term outcomes compared with those without thrombolysis treatment (23 patients). Patients with both vascular stenosis and blood flow mismatch (13 patients) exhibited the best short-term outcome, while there was no correlation of long-term outcome with CT angiography or CT perfusion findings. These data suggest that combined CT perfusion and CT angiography are useful for predicting short-term outcome, but not long-term outcome, after thrombolysis.

Utility of perfusion imaging in acute stroke treatment: a systematic review and meta-analysis

BACKGROUND

Variability in imaging protocols and techniques has resulted in a lack of consensus regarding the incorporation of perfusion imaging into stroke triage and treatment. The objective of our study was to evaluate the available scientific evidence regarding the utility of perfusion imaging in determining treatment eligibility in patients with acute stroke and in predicting their clinical outcome.

METHODS

We performed a systematic review of the literature using PubMed, Web of Science, and Cochrane Library focusing on themes of medical imaging, stroke, treatment, and outcome (CRD42016037817). We included randomized controlled trials, cohort studies, and case-controlled studies published from 2011 to 2016. Two independent reviewers conducted the study appraisal, data abstraction, and quality assessments of the studies.

RESULTS

Our literature search yielded 13 studies that met our inclusion criteria. In total, 994 patients were treated with the aid of perfusion imaging compared with 1819 patients treated with standard care. In the intervention group 51.1% of patients had a favorable outcome at 3 months compared with 45.6% of patients in the control group (p=0.06). Subgroup analysis of studies that used multimodal therapy (IV tissue plasminogen activator, endovascular thrombectomy) showed a significant benefit of perfusion imaging (OR 1.89, 95% CI 1.43 to 2.51, p<0.01).

CONCLUSIONS

Perfusion imaging may represent a complementary tool to standard radiographic assessment in enhancing patient selection for reperfusion therapy, with a subset of patients having up to 1.9 times the odds of achieving independent functional status at 3 months. This is particularly important as patients selected based on perfusion status often included individuals who did not meet the current treatment eligibility criteria.

The Oxfordshire Community Stroke Project classification system predicts clinical outcomes following intravenous thrombolysis: a prospective cohort study

Background

The Oxfordshire Community Stroke Project (OCSP) classification system is a simple stroke classification system that can be used to predict clinical outcomes. In this study, we compare the safety and efficacy of intravenous thrombolysis in Chinese stroke patients categorized using the OCSP classification system.

Patients and methods

We collected data from the Thrombolysis Implementation and Monitoring of Acute Ischemic Stroke in China registry. A total of 1,115 patients treated with intravenous thrombolysis with alteplase within 4.5 hours of stroke onset were included. Symptomatic intracranial hemorrhage (SICH), mortality, and 90-day functional outcomes were compared between the stroke patients with different stroke subtypes.

Results

Of the 1,115 patients included in the cohort, 197 (17.67%) were classified with total anterior circulation infarct (TACI), 700 (62.78%) with partial anterior circulation infarct, 153 (13.72%) with posterior circulation infarct, and 65 (5.83%) with lacunar infarct. After multivariable adjustment, compared to the patients with non-TACI, those with TACI had a significantly increased risk of SICH (odds ratio [OR] 8.80; 95% confidence interval [CI] 2.84–27.25, P<0.001), higher mortality (OR 5.24; 95% CI 3.19–8.62; P<0.001), and poor functional independence (OR 0.38; 95% CI 0.26–0.56; P<0.001) at 3-month follow-up.

Conclusion

After thrombolysis, the patients with TACI exhibited greater SICH, a higher mortality rate, and worse 3-month clinical outcomes compared with the patients with non-TACI. The OCSP classification system may help clinicians predict the safety and efficacy of thrombolysis.

CT Permeability Imaging Predicts Clinical Outcomes in Acute Ischemic Stroke Patients Treated with Intra-arterial Thrombolytic Therapy

In this study, we determined whether a prediction of final infarct volume (FIV) and clinical outcomes in patients with an acute stroke is improved by using a contrast transfer coefficient (K ^trans) as a biomarker for blood-brain barrier (BBB) dysfunction. Here, consecutive patients admitted with signs and symptoms suggesting acute hemispheric stroke were included in this study. Ninety-eight participants with intra-arterial therapy were assessed (46 female). Definition of predicted FIV was performed using conventional perfusion CT (PCT-PIV) parameters alone and in combination with K ^trans (K ^trans-PIV). Multiple logistic regression analyses and linear regression modeling were conducted to determine independent predictors of the 90-day modified Rankin score (mRS) and FIV, respectively. We found that patients with favorable outcomes were younger and had lower National Institutes of Health Stroke Scale (NIHSS) score, smaller PCT-PIV, K ^trans-PIV, and smaller FIV (P < 0.001). K ^trans-PIV showed good correlation with FIV (P < 00.001, R ² = 0.6997). In the regression analyses, K ^trans-PIV was the best predictor of clinical outcomes (P = 0.009, odds ratio (OR) = 1.960) and also the best predictor for FIV (F = 75.590, P < 0.0001). In conclusion, combining PCT and K ^trans maps derived from first-pass PCT can identify at-risk cerebral ischemic tissue more precisely than perfusion parameters alone. This provides improved accuracy in predicting FIV and clinical outcomes.

Perfusion Deficits and Mismatch in Patients with Acute Lacunar Infarcts Studied with Whole-Brain CT Perfusion

BACKGROUND AND PURPOSE

The incidence and significance of perfusion abnormalities on brain imaging in patients with lacunar infarct are controversial. We studied the diagnostic yield of CTP and the type of perfusion abnormalities in patients presenting with a lacunar syndrome and in those with MR imaging-confirmed lacunar infarcts.

MATERIALS AND METHODS

A cohort of 33 patients with lacunar syndrome underwent whole-brain CTP on admission. Twenty-eight patients had an acute ischemic lesion at follow-up MR imaging; 16 were classified as lacunar infarcts. Two independent readers evaluated NCCT and CTP to compare their diagnostic yield. In patients with DWI-confirmed lacunar infarcts and visible deficits on CTP, the presence of mismatch tissue was measured by using different perfusion thresholds.

RESULTS

The symptomatic acute lesion was seen on CTP in 50% of patients presenting with a lacunar syndrome compared with only 17% on NCCT, and in 62% on CTP compared with 19% on NCCT, respectively, in patients with DWI-confirmed lacunar infarcts. CTP was more sensitive in supratentorial than in infratentorial lesions. In the nonblinded analysis, a perfusion deficit was observed in 12/16 patients with DWI-confirmed lacunar infarcts. The proportion of mismatch tissue was similar in patients with lacunar infarcts or nonlacunar strokes (32% versus 36%, P = .734).

CONCLUSIONS

Whole-brain CTP is superior to NCCT in identifying small ischemic lesions, including lacunar infarcts, in patients presenting with a lacunar syndrome. Perfusion deficits and mismatch are frequent in lacunar infarcts, but larger studies are warranted to elucidate the clinical significance of these CTP findings.

Contribution and additional impact of imaging to the SPAN-100 score

BACKGROUND AND PURPOSE

Stroke Prognostication by Using Age and NIHSS score (SPAN-100 index) facilitates stroke outcomes. We assessed imaging markers associated with the SPAN-100 index and their additional impact on outcome determination.

MATERIALS AND METHODS

Of 273 consecutive patients with acute ischemic stroke (<4.5 hours), 55 were characterized as SPAN-100-positive (age +NIHSS score ≥ 100). A comprehensive imaging review evaluated differences, using the presence of the hyperattenuated vessel sign, ASPECTS, clot burden score, collateral score, CBV, CBF, and MTT. The primary outcome assessed was favorable outcome (mRS ≤ 2). Secondary outcomes included recanalization, lack of neurologic improvement, and hemorrhagic transformation. Uni- and multivariate analyses assessed factors associated with favorable outcome. Area under the curve evaluated predictors of favorable clinical outcome.

RESULTS

Compared with the SPAN-100-negative group, the SPAN-100-positive group (55/273; 20%) demonstrated larger CBVs (<0.001), poorer collaterals (P < .001), and increased hemorrhagic transformation rates (56.0% versus 36%, P = .02) despite earlier time to rtPA (P = .03). Favorable outcome was less common among patients with SPAN-100-positive compared with SPAN-100-negative (10.9% versus 42.2%; P < .001). Multivariate regression revealed poorer outcome for SPAN-100-positive (OR = 0.17; 95% CI, 0.06-0.38; P = .001), clot burden score (OR = 1.14; 95% CI, 1.05-1.25; P < .001), and CBV (OR = 0.58; 95% CI, 0.46-0.72; P = .001). The addition of the clot burden score and CBV improved the predictive value of SPAN-100 alone for favorable outcome from 60% to 68% and 74%, respectively.

CONCLUSIONS

SPAN-100-positivity predicts a lower likelihood of favorable outcome and increased hemorrhagic transformation. CBV and clot burden score contribute to poorer outcomes among high-risk patients and improve stroke-outcome prediction.

Relevance of blood-brain barrier disruption after endovascular treatment of ischemic stroke: dual-energy computed tomographic study

BACKGROUND AND PURPOSE

Computed tomographic (CT) high attenuation (HA) areas after endovascular therapy for acute ischemic stroke are a common finding indicative of blood-brain barrier disruption. Dual-energy CT allows an accurate differentiation between HA areas related to contrast staining (CS) or to brain hemorrhage (BH). We sought to evaluate the prognostic significance of the presence of CS and BH after endovascular therapy.

METHODS

A prospective cohort of 132 patients treated with endovascular therapy was analyzed. According to dual-energy CT findings, patients were classified into 3 groups: no HA areas (n=53), CS (n=32), and BH (n=47). The rate of new hemorrhagic transformations was recorded at follow-up neuroimaging. Clinical outcome was evaluated at 90 days with the modified Rankin Scale (poor outcome, 3-6).

RESULTS

Poor outcome was associated with the presence of CS (odds ratio [OR], 11.3; 95% confidence interval, 3.34-38.95) and BH (OR, 10.4; 95% confidence interval, 3.42-31.68). The rate of poor outcome despite complete recanalization was also significantly higher in CS (OR, 9.7; 95% confidence interval, 2.55-37.18) and BH (OR, 15.1; 95% confidence interval, 3.85-59.35) groups, compared with the no-HA group. Patients with CS disclosed a higher incidence of delayed hemorrhagic transformation at follow-up (OR, 4.5; 95% confidence interval, 1.22-16.37) compared with no-HA patients.

CONCLUSIONS

Blood-brain barrier disruption, defined as CS and BH on dual-energy CT, was associated with poor clinical outcomes in patients with stroke treated with endovascular therapies. Moreover, isolated CS was associated with delayed hemorrhagic transformation. These results support the clinical relevance of blood-brain barrier disruption in acute stroke.

Reperfusion therapies for acute ischemic stroke: an update

Acute ischemic stroke is a major cause of morbidity and mortality in developed countries. Intravenous thrombolysis with tissue plasminogen activator (tPA) within 4.5 hours of symptoms onset significantly improves clinical outcomes in patients with acute ischemic stroke. This narrow window for treatment leads to a small proportion of eligible patients to be treated. Intravenous or intra-arterial trials, combined intravenous/intra-arterial trials, and newer devices to mechanically remove the clot from intracranial arteries have been investigated or are currently being explored to increase patient eligibility and to improve arterial recanalization and clinical outcome. New retrievable stent-based devices offer higher revascularization rates with shorter time to recanalization and are now generally preferred to first generation thrombectomy devices such as Merci Retriever or Penumbra System. These devices have been shown to be effective for opening up occluded vessels in the brain but its efficacy for improving outcomes in patients with acute stroke has not yet been demonstrated in a randomized clinical trial. We summarize the results of the major systemic thrombolytic trials and the latest trials employing different endovascular approaches to ischemic stroke.

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.

Pretreatment advanced imaging in patients with stroke treated with IV thrombolysis: evaluation of a multihospital data base

BACKGROUND AND PURPOSE

CT angiography, CT perfusion, and MR imaging have all been advocated as potentially useful in treatment planning for patients with acute ischemic stroke. We evaluated a large multihospital data base to determine how the use of advanced imaging is evolving in patients treated with intravenous thrombolysis.

MATERIALS AND METHODS

Patients with acute ischemic stroke receiving IV thrombolytic therapy from 2008 to 2011 were identified by using the Premier Perspective data base. Mortality and discharge to long-term care rates were compared following multivariate logistic regression between patients who received head CT only versus those who received CTA without CT perfusion, CT perfusion, or MR imaging.

RESULTS

Of 12,429 included patients, 7305 (59%) were in the CT group, 2359 (19%) were in the CTA group, 848 (7%) were in the CTP group, and 1917 (15%) were in the MR group. From 2008 to 2011, the percentage of patients receiving head CT only decreased from 64% to 55%, while the percentage who received cerebral CT perfusion increased from 3% to 8%. The use of CT angiography and MR imaging marginally increased (1%-2%). Outcomes were similar between CT only and advanced imaging patients, except discharge to long-term care was slightly more frequent in the CTP group (OR = 1.17 [95% CI, 0.96-1.43]; P = .0412) and MR group (OR = 1.14 [95% CI, 1.01-1.28]; P = .0177) and mortality was lower in the MR group (OR = 0.64 [95% CI, 0.52-0.79]; P < .0001).

CONCLUSIONS

Use of advanced imaging is increasing in patients treated with IV thrombolysis. While there were differences in outcomes among imaging groups, the clinical effect of advanced imaging remains unclear.

Ischemic stroke in evolution: predictive value of perfusion computed tomography

BACKGROUND

Various perfusion computed tomography (PCT) parameters have been used to identify tissue at risk of infarction in the setting of acute stroke. The purpose of this study was to examine predictive value of the PCT parameters commonly used in clinical practice to define ischemic penumbra. The patient selection criterion aimed to exclude the effect of thrombolysis from the imaging data.

METHODS

Consecutive acute stroke patients were screened and a total of 18 patients who initially underwent PCT and CT angiogram (CTA) on presentation but did not qualify to receive thrombolytic therapy were selected. The PCT images were postprocessed using a delay-sensitive deconvolution algorithm. All the patients had follow-up noncontrast CT or magnetic resonance imaging to delineate the extent of their infarction. The extent of lesions on PCT maps calculated from mean transit time (MTT), time to peak (TTP), cerebral blood flow, and cerebral blood volume were compared and correlated with the final infarct size. A collateral grading score was used to measure collateral blood supply on the CTA studies.

RESULTS

The average size of MTT lesions was larger than infarct lesions (P < .05). The correlation coefficient of TTP/infarct lesions (r = .95) was better than MTT/infarct lesions (r = .66) (P = .004).

CONCLUSIONS

A widely accepted threshold to define MTT lesions overestimates the ischemic penumbra. In this setting, TTP with appropriate threshold is a better predictor of infarct in acute stroke patients. The MTT/TTP mismatch correlates with the status of collateral blood supply to the tissue at risk of infarction.

Location of the clot and outcome of perfusion defects in acute anterior circulation stroke treated with intravenous thrombolysis

BACKGROUND AND PURPOSE

The location of the clot is a major determinant of ischemic stroke outcome. We studied the impact of the location (ICA, proximal M1 segment of the MCA, distal M1 segment, and M2 segment and more distally) of the clot on the CT perfusion parametric maps, the mismatch ratio, the amount of salvaged brain tissue, and the imaging and clinical outcomes in a retrospective acute (<3 hours) stroke cohort treated with intravenous thrombolysis.

MATERIALS AND METHODS

We reviewed 105 patients who underwent admission multimodal CT that revealed an occluded vessel on CTA. CT perfusion was successfully performed in 58 patients (55%). Differences among the parameters in different vessel positions were studied with the ANCOVA by using onset-to-imaging time as a covariate followed by pair-wise testing.

RESULTS

There were no significant differences in potential confounding variables among the groups. A clot proximal to the M2 segment produced a significantly larger defect on the MTT map. A clot in the ICA resulted in a significantly larger CBV lesion compared with the distal M1 segment, the M2 segment, and the M3 segment. In general, a more proximal thrombus created a larger CBV defect. The fraction of penumbra that was salvaged at 24 hours was higher in the more distal vessel positions.

CONCLUSIONS

Admission CBV defects are larger in proximal vessel occlusions. More of the penumbra can be salvaged if the occlusion is located distally. This effect seems to reach a plateau in the distal M1 segment of the MCA.

Clinical use of computed tomographic perfusion for the diagnosis and prediction of lesion growth in acute ischemic stroke

BACKGROUND

Computed tomography perfusion (CTP) mapping in research centers correlates well with diffusion-weighted imaging (DWI) lesions and may accurately differentiate the infarct core from ischemic penumbra. The value of CTP in real-world clinical practice has not been fully established. We investigated the yield of CTP-derived cerebral blood volume (CBV) and mean transient time (MTT) for the detection of cerebral ischemia and ischemic penumbra in a sample of acute ischemic stroke (AIS) patients.

METHODS

We studied 165 patients with initial clinical symptoms suggestive of AIS. All patients had an initial noncontrast head CT, CTP, CT angiogram (CTA), and follow-up magnetic resonance imaging (MRI) of the brain. The obtained perfusion images were used for image processing. CBV, MTT, and DWI lesion volumes were visually estimated and manually traced. Statistical analysis was conducted using R and SAS software.

RESULTS

All normal DWI sequences had normal CBV and MTT studies (N = 89). Seventy-three patients had acute DWI lesions. CBV was abnormal in 23.3% and MTT was abnormal in 42.5% of these patients. There was a high specificity (91.8%) but poor sensitivity (40.0%) for MTT maps predicting positive DWI. The Spearman correlation was significant between MTT and DWI lesions (ρ = 0.66; P > .0001) only for abnormal MTT and DWI lesions >0 cc. CBV lesions did not correlate with final DWI.

CONCLUSIONS

In real-world use, acute imaging with CTP did not predict stroke or DWI lesions with sufficient accuracy. Our findings argue against the use of CTP for screening AIS patients until real-world implementations match the accuracy reported from specialized research centers.

Single-center experience of cerebral artery thrombectomy using the TREVO device in 60 patients with acute ischemic stroke

BACKGROUND AND PURPOSE

We sought to explore the safety and efficacy of the new TREVO stent-like retriever in consecutive patients with acute stroke.

METHODS

We conducted a prospective, single-center study of 60 patients (mean age, 71.3 years; male 47%) with stroke lasting <8 hours in the anterior circulation (n=54) or <12 hours in the vertebrobasilar circulation (n=6) treated if CT perfusion/CT angiography confirmed a large artery occlusion, ruled out a malignant profile, or showed target mismatch if symptoms >4.5 hours. Successful recanalization (Thrombolysis In Cerebral Infarction 2b-3), good outcome (modified Rankin Scale score 0-2) and mortality at Day 90, device-related complications, and symptomatic hemorrhage (parenchymal hematoma Type 1 or parenchymal hematoma Type 2 and National Institutes of Health Stroke Scale score increment ≥ 4 points) were prospectively assessed.

RESULTS

Median (interquartile range) National Institutes of Health Stroke Scale score on admission was 18 (12-22). The median (interquartile range) time from stroke onset to groin puncture was 210 (173-296) minutes. Successful revascularization was obtained in 44 (73.3%) of the cases when only the TREVO device was used and in 52 (86.7%) when other devices or additional intra-arterial tissue-type plasminogen activator were also required. The median time (interquartile range) of the procedure was 80 (45-114) minutes. Good outcome was achieved in 27 (45%) of the patients and the mortality rate was 28.3%. Seven patients (11.7%) presented a symptomatic intracranial hemorrhage. No other major complications were detected.

CONCLUSIONS

The TREVO device was reasonably safe and effective in patients with severe stroke. These results support further investigation of the TREVO device in multicentric registries and randomized clinical trials.

Improved outcome prediction using CT angiography in addition to standard ischemic stroke assessment: results from the STOPStroke study

PURPOSE

To improve ischemic stroke outcome prediction using imaging information from a prospective cohort who received admission CT angiography (CTA).

METHODS

In a prospectively designed study, 649 stroke patients diagnosed with acute ischemic stroke had admission NIH stroke scale scores, noncontrast CT (NCCT), CTA, and 6-month outcome assessed using the modified Rankin scale (mRS) scores. Poor outcome was defined as mRS>2. Strokes were classified as "major" by the (1) Alberta Stroke Program Early CT Score (ASPECTS+) if NCCT ASPECTS was ≤7; (2) Boston Acute Stroke Imaging Scale (BASIS+) if they were ASPECTS+ or CTA showed occlusion of the distal internal carotid, proximal middle cerebral, or basilar arteries; and (3) NIHSS for scores >10.

RESULTS

Of 649 patients, 253 (39.0%) had poor outcomes. NIHSS, BASIS, and age, but not ASPECTS, were independent predictors of outcome. BASIS and NIHSS had similar sensitivities, both superior to ASPECTS (p<0.0001). Combining NIHSS with BASIS was highly predictive: 77.6% (114/147) classified as NIHSS>10/BASIS+ had poor outcomes, versus 21.5% (77/358) with NIHSS≤10/BASIS- (p<0.0001), regardless of treatment. The odds ratios for poor outcome is 12.6 (95% CI: 7.9 to 20.0) in patients who are NIHSS>10/BASIS+ compared to patients who are NIHSS≤10/BASIS-; the odds ratio is 5.4 (95% CI: 3.5 to 8.5) when compared to patients who are only NIHSS>10 or BASIS+.

CONCLUSIONS

BASIS and NIHSS are independent outcome predictors. Their combination is stronger than either instrument alone in predicting outcomes. The findings suggest that CTA is a significant clinical tool in routine acute stroke assessment.

CT perfusion mean transit time maps optimally distinguish benign oligemia from true "at-risk" ischemic penumbra, but thresholds vary by postprocessing technique

BACKGROUND AND PURPOSE

Various CTP parameters have been used to identify ischemic penumbra. The purpose of this study was to determine the optimal CTP parameter and threshold to distinguish true "at-risk" penumbra from benign oligemia in acute stroke patients without reperfusion.

MATERIALS AND METHODS

Consecutive stroke patients were screened and 23 met the following criteria: 1) admission scanning within 9 hours of onset, 2) CTA confirmation of large vessel occlusion, 3) no late clinical or radiographic evidence of reperfusion, 4) no thrombolytic therapy, 5) DWI imaging within 3 hours of CTP, and 6) either CT or MR follow-up imaging. CTP was postprocessed with commercial software packages, using standard and delay-corrected deconvolution algorithms. Relative cerebral blood flow, volume, and mean transit time (rCBF, rCBV and rMTT) values were obtained by normalization to the uninvolved hemisphere. The admission DWI and final infarct were transposed onto the CTP maps and receiver operating characteristic curve analysis was performed to determine optimal thresholds for each perfusion parameter in defining penumbra destined to infarct.

RESULTS

Relative and absolute MTT identified penumbra destined to infarct more accurately than CBF or CBV*CBF (P < .01). Absolute and relative MTT thresholds for defining penumbra were 12s and 249% for the standard and 13.5s and 150% for the delay-corrected algorithms, respectively.

CONCLUSIONS

Appropriately thresholded absolute and relative MTT-CTP maps optimally distinguish "at-risk" penumbra from benign oligemia in acute stroke patients with large-vessel occlusion and no reperfusion. The precise threshold values may vary, however, depending on the postprocessing technique used for CTP map construction.

Perfusion-CT guided intravenous thrombolysis in patients with unknown-onset stroke: a randomized, double-blind, placebo-controlled, pilot feasibility trial

INTRODUCTION

Patients with unknown stroke onset are generally excluded from acute recanalisation treatments. We designed a pilot study to assess feasibility of a trial of perfusion computed tomography (PCT)-guided thrombolysis in patients with ischemic tissue at risk of infarction and unknown stroke onset.

METHODS

Patients with a supratentorial stroke of unknown onset in the middle cerebral artery territory and significant volume of at-risk tissue on PCT were randomized to intravenous thrombolysis with alteplase (0.9 mg/kg) or placebo. Feasibility endpoints were randomization and blinded treatment of patients within 2 h after hospital arrival, and the correct application (estimation) of the perfusion imaging criteria.

RESULTS

At baseline, there was a trend towards older age [69.5 (57-78) vs. 49 (44-78) years] in the thrombolysis group (n = 6) compared to placebo (n = 6). Regarding feasibility, hospital arrival to treatment delay was above the allowed 2 h in three patients (25%). There were two protocol violations (17%) regarding PCT, both underestimating the predicted infarct in patients randomized in the placebo group. No symptomatic hemorrhage or death occurred during the first 7 days. Three of the four (75%) and one of the five (20%) patients were recanalized in the thrombolysis and placebo group respectively. The volume of non-infarcted at-risk tissue was 84 (44-206) cm(3) in the treatment arm and 29 (8-105) cm(3) in the placebo arm.

CONCLUSIONS

This pilot study shows that a randomized PCT-guided thrombolysis trial in patients with stroke of unknown onset may be feasible if issues such as treatment delays and reliable identification of tissue at risk of infarction tissue are resolved. Safety and efficiency of such an approach need to be established.