Acute stroke: usefulness of early CT findings before thrombolytic therapy

Movement disorders following mechanical thrombectomy resulting in ischemic lesions of the basal ganglia: An emerging clinical entity

BACKGROUND AND PURPOSE

Post-stroke movement disorders (PMDs) following ischemic lesions of the basal ganglia (BG) are a known entity, but data regarding their incidence are lacking. Ischemic strokes secondary to proximal middle cerebral artery (MCA) occlusion treated with thrombectomy represent a model of selective damage to the BG. The aim of this study was to assess the prevalence and features of movement disorders after selective BG ischemia in patients with successfully reperfused acute ischemic stroke (AIS).

METHODS

We enrolled 64 consecutive subjects with AIS due to proximal MCA occlusion treated with thrombectomy. Patients were clinically evaluated by a movement disorders specialist for PMDs onset at baseline, and after 6 and 12 months.

RESULTS

None of the patients showed an identifiable movement disorder in the subacute phase of the stroke. At 6 and 12 months, respectively, 7/25 (28%) and 7/13 (53.8%) evaluated patients developed PMDs. The clinical spectrum of PMDs encompassed parkinsonism, dystonia and chorea, either isolated or combined. In most patients, symptoms were contralateral to the lesion, although a subset of patients presented with bilateral involvement and prominent axial signs.

CONCLUSION

Post-stroke movement disorders are not uncommon in long-term follow-up of successfully reperfused AIS. Follow-up conducted by a multidisciplinary team is strongly advisable in patients with selective lesions of the BG after AIS, even if asymptomatic at discharge.

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

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

Clinical relevance of intracranial hemorrhage after thrombectomy versus medical management for large core infarct: a secondary analysis of the SELECT2 randomized trial

BACKGROUND

The incidence of intracerebral hemorrhage (ICH) and its effect on the outcomes after endovascular thrombectomy (EVT) for patients with large core infarcts have not been well-characterized.

METHODS

SELECT2 trial follow-up imaging was evaluated using the Heidelberg Bleeding Classification (HBC) to define hemorrhage grade. The association of ICH with clinical outcomes and treatment effect was examined.

RESULTS

Of 351 included patients, 194 (55%) and 189 (54%) demonstrated intracranial and intracerebral hemorrhage, respectively, with a higher incidence in EVT (134 (75%) and 130 (73%)) versus medical management (MM) (60 (35%) and 59 (34%), both P<0.001). Hemorrhagic infarction type 1 (HBC=1a) and type 2 (HBC=1b) accounted for 93% of all hemorrhages. Parenchymal hematoma (PH) type 1 (HBC=1c) and type 2 (HBC=2) were observed in 1 (0.6%) EVT-treated and 4 (2.2%) MM patients. Symptomatic ICH (sICH) (SITS-MOST definition) was seen in 0.6% EVT patients and 1.2% MM patients. No trend for ICH with core volumes (P=0.10) or Alberta Stroke Program Early CT Score (ASPECTS) (P=0.74) was observed. Among EVT patients, the presence of any ICH did not worsen clinical outcome (modified Rankin Scale (mRS) at 90 days: 4 (3-6) vs 4 (3-6); adjusted generalized OR 1.00, 95% CI 0.68 to 1.47, P>0.99) or modify EVT treatment effect (Pinteraction=0.77).

CONCLUSIONS

ICH was present in 75% of the EVT population, but PH or sICH were infrequent. The presence of any ICH did not worsen functional outcomes or modify EVT treatment effect at 90-day follow-up. The high rate of hemorrhages overall still represents an opportunity for adjunctive therapies in EVT patients with a large ischemic core.

Definition, prediction, prevention and management of patients with severe ischemic stroke and large infarction

ABSTRACT

Severe ischemic stroke carries a high rate of disability and death. The severity of stroke is often assessed by the degree of neurological deficits or the extent of brain infarct, defined as severe stroke and large infarction, respectively. Critically severe stroke is a life-threatening condition that requires neurocritical care or neurosurgical intervention, which includes stroke with malignant brain edema, a leading cause of death during the acute phase, and stroke with severe complications of other vital systems. Early prediction of high-risk patients with critically severe stroke would inform early prevention and treatment to interrupt the malignant course to fatal status. Selected patients with severe stroke could benefit from intravenous thrombolysis and endovascular treatment in improving functional outcome. There is insufficient evidence to inform dual antiplatelet therapy and the timing of anticoagulation initiation after severe stroke. Decompressive hemicraniectomy (DHC) <48 h improves survival in patients aged <60 years with large hemispheric infarction. Studies are ongoing to provide evidence to inform more precise prediction of malignant brain edema, optimal indications for acute reperfusion therapies and neurosurgery, and the individualized management of complications and secondary prevention. We present an evidence-based review for severe ischemic stroke, with the aims of proposing operational definitions, emphasizing the importance of early prediction and prevention of the evolution to critically severe status, summarizing specialized treatment for severe stroke, and proposing directions for future research.

Benefit and risk of intravenous alteplase in patients with acute large vessel occlusion stroke and low ASPECTS

BACKGROUND

The benefit of best medical treatment including intravenous alteplase (IVT) before mechanical thrombectomy (MT) in patients with acute ischemic stroke and extensive early ischemic changes on baseline CT remains uncertain. The purpose of this study was to evaluate the benefit of IVT for patients with low ASPECTS (Alberta Stroke Programme Early CT Score) compared with patients with or without MT.

METHODS

This multicenter study pooled consecutive patients with anterior circulation acute stroke and ASPECTS≤5 to analyze the impact of IVT on functional outcome, and to compare bridging IVT with direct MT. Functional endpoints were the rates of good (modified Rankin Scale (mRS) score ≤2) and very poor (mRS ≥5) outcome at day 90. Safety endpoint was the occurrence of symptomatic intracranial hemorrhage (sICH).

RESULTS

429 patients were included. 290 (68%) received IVT and 168 (39%) underwent MT. The rate of good functional outcome was 14.4% (95% CI 7.1% to 21.8%) for patients who received bridging IVT and 24.4% (95% CI 16.5% to 32.2%) for those who underwent direct MT. The rate of sICH was significantly higher in patients with bridging IVT compared with direct MT (17.8% vs 6.4%, p=0.004). In multivariable logistic regression analysis, IVT was significantly associated with very poor outcome (OR 2.22, 95% CI 1.05 to 4.73, p=0.04) and sICH (OR 3.44, 95% CI 1.18 to 10.07, p=0.02). Successful recanalization, age, and ASPECTS were associated with good functional outcome.

CONCLUSIONS

Bridging IVT in patients with low ASPECTS was associated with very poor functional outcome and an increased risk of sICH. The benefit of this treatment should therefore be carefully weighed in such scenarios. Further randomized controlled trials are required to validate our findings.

Improving the diagnosis of acute ischemic stroke on non-contrast CT using deep learning: a multicenter study

OBJECTIVE

This study aimed to develop a deep learning (DL) model to improve the diagnostic performance of EIC and ASPECTS in acute ischemic stroke (AIS).

METHODS

Acute ischemic stroke patients were retrospectively enrolled from 5 hospitals. We proposed a deep learning model to simultaneously segment the infarct and estimate ASPECTS automatically using baseline CT. The model performance of segmentation and ASPECTS scoring was evaluated using dice similarity coefficient (DSC) and ROC, respectively. Four raters participated in the multi-reader and multicenter (MRMC) experiment to fulfill the region-based ASPECTS reading under the assistance of the model or not. At last, sensitivity, specificity, interpretation time and interrater agreement were used to evaluate the raters' reading performance.

RESULTS

In total, 1391 patients were enrolled for model development and 85 patients for external validation with onset to CT scanning time of 176.4 ± 93.6 min and NIHSS of 5 (IQR 2-10). The model achieved a DSC of 0.600 and 0.762 and an AUC of 0.876 (CI 0.846-0.907) and 0.729 (CI 0.679-0.779), in the internal and external validation set, respectively. The assistance of the DL model improved the raters' average sensitivities and specificities from 0.254 (CI 0.22-0.26) and 0.896 (CI 0.884-0.907), to 0.333 (CI 0.301-0.345) and 0.915 (CI 0.904-0.926), respectively. The average interpretation time of the raters was reduced from 219.0 to 175.7 s (p = 0.035). Meanwhile, the interrater agreement increased from 0.741 to 0.980.

CONCLUSIONS

With the assistance of our proposed DL model, radiologists got better performance in the detection of AIS lesions on NCCT.

Endovascular treatment for anterior circulation large-vessel occlusion ischemic stroke with low ASPECTS: a systematic review and meta-analysis

BACKGROUND

Endovascular treatment (EVT) for acute ischemic stroke (AIS) patients presenting with Alberta Stroke Program Early CT Score (ASPECTS) 0-5 has not yet proven safe and effective by clinical trials.

OBJECTIVES

The aim of the study was to assess whether EVT in AIS patients presenting with low ASPECTS is beneficial.

DESIGN

Systematic review and meta-analysis of available studies in accordance with the PRISMA statement.

DATA SOURCES AND METHODS

We have searched MEDLINE, the Cochrane Central Register of Controlled Trials, and reference lists of articles published until 28 May 2022 with the aim to calculate (1) modified Rankin scale (mRS) score 0-3 at 3 months, (2) mRS score 0-2 at 3 months, (3) symptomatic intracranial hemorrhage (sICH), and (3) mortality at 3 months.

RESULTS

Overall, 24 eligible studies were included in the meta-analysis, comprising a total of 2539 AIS patients with ASPECTS 0-5 treated with EVT. The pooled proportion of EVT-treated patients achieving mRS 0-3 at 3 months was calculated at 38.4%. The pooled proportion of EVT-treated patients achieving mRS 0-2 at 3 months was 25.7%. Regarding safety outcomes, sICH occurred in 12.8% of patients. The 3-month pooled mortality was 30%. In pairwise meta-analysis, patients treated with EVT had a higher likelihood of achieving mRS 0-3 at 3 months compared with patients treated with best medical therapy (BMT, OR: 2.41). sICH occurred more frequently in EVT-treated patients compared with the BMT-treated patients (OR: 2.30). Mortality at 3 months was not different between the two treatment groups (OR: 0.71).

CONCLUSION

EVT may be beneficial for AIS patients with low baseline ASPECTS despite an increased risk for sICH. Further data from randomized-controlled clinical trials are needed to elucidate the role of EVT in this subgroup of AIS patients.

REGISTRATION

The protocol has been registered in the International Prospective Register of Ongoing Systematic Reviews PROSPERO; Registration Number: CRD42022334417.

A clinical application study of a stent placement assessment

BACKGROUND

Atherosclerotic acute carotid occlusion is a specific type of stroke, and controversy exists regarding the surgical strategy, that is, whether an internal carotid artery stent should be placed immediately after opening the occluded vessel. There is no objective evaluation system for this procedure. In a previous study, we summarized an evaluation decision system Emergent Carotid Artery Stent placement decision Evaluation System (ECASES) for emergency stent placement.

STUDY DESIGN

This is a prospective, single-center, randomized controlled trial. Patients with acute ischemic stroke caused by atherosclerotic carotid artery occlusion confirmed by imaging (computed tomography/magnetic resonance angiography/digital subtraction angiography) will be randomly divided into the study and control groups, with 101 patients in each group. The study group will undergo surgery according to the ECASES system and the control group will undergo surgery according to the operator's experience. The postoperative outcomes of the 2 groups will be compared.

STUDY OUTCOMES

Primary outcome: Neurological functional status (modified Rankin Scale and National Institutes of Health Stroke Scale scores) of patients 90 days postoperatively. Secondary outcomes: neurological function changes, hemorrhage events, cerebral edema, postoperative modified treatment in cerebral infarction grade, new cerebral infarction, and reocclusion of responsible vessels.

DISCUSSION

Currently, no prospective controlled data exist regarding the efficacy and safety of carotid stenting in the acute phase. Previously, we had developed an ECASES stent placement system for acute carotid artery occlusion. The present study will evaluate the efficacy and safety of ECASES in a randomized, double-blind prospective study and clarify its guiding significance in acute atherosclerotic carotid artery occlusion surgery.

Association of Thrombectomy With Functional Outcome for Patients With Ischemic Stroke Who Presented in the Extended Time Window With Extensive Signs of Infarction

IMPORTANCE

Only limited data are available about a potential benefit associated with endovascular treatment (EVT) for patients with ischemic stroke presenting in the extended time window who also show signs of extensive infarction.

OBJECTIVE

To assess the association of recanalization after EVT with functional outcomes for patients with ischemic stroke presenting in the extended time window who also show signs of extensive infarction.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective, multicenter cohort study included patients enrolled in the German Stroke Registry-Endovascular Treatment with an Alberta Stroke Program Early CT Score (ASPECTS) of 5 or less who presented between 6 and 24 hours after stroke onset and underwent computed tomography and subsequent EVT between July 1, 2015, and December 31, 2019.

MAIN OUTCOMES AND MEASURES

The primary end point was a modified Rankin Scale (mRS) score of 3 or less at day 90. The association between recanalization (defined as the occurrence of a modified Thrombolysis in Cerebral Infarction Scale score of 2b or 3) and outcome was assessed using logistic regression and inverse probability weighting analysis.

INTERVENTION

Endovascular treatment.

RESULTS

Of 5853 patients, 285 (5%; 146 men [51%]; median age, 73 years [IQR, 62-81 years]) met the inclusion criteria and were analyzed. Of these 285 patients, 79 (27.7%) had an mRS score of 3 or less at day 90. The rate of successful recanalization was 75% (215 of 285) and was independently associated with a higher probability of reaching an mRS score of 3 or less (adjusted odds ratio, 4.39; 95% CI, 1.79-10.72; P < .001). In inverse probability weighting analysis, a modified Thrombolysis in Cerebral Infarction Scale score of 2b or 3 was associated with a 19% increase (95% CI, 9%-29%; P < .001) in the probability for an mRS score of 3 or more. Multivariable logistic regression analysis suggested a significant treatment benefit associated with vessel recanalization in a time window of up to 17.6 hours and ASPECTS of 3 to 5. The rate of secondary symptomatic intracerebral hemorrhage was 6.3% (18 of 285).

CONCLUSIONS AND RELEVANCE

In this cohort study reflecting daily clinical practice, vessel recanalization for patients with a low ASPECTS and extended time window was associated with better functional outcomes in a time window up to 17.6 hours and ASPECTS of 3 to 5. The results of this study encourage current randomized clinical trials to enroll patients with a low ASPECTS, even within the extended time window.

When Can an Emergency CTA Be Dispensed with for TIA Patients?

Background: Transient ischemic attacks (TIAs) and minor strokes are often precursors of a major stroke. Therefore, diagnostic work-up of the TIA is essential to reduce the patient’s risk of further ischemic events. Purpose: With the help of this retrospective study, we aim to determine for which TIA patients a CT angiography (CTA) is not immediately necessary in order to reduce radiation exposure and nephrotoxicity. Material and Methods: Clinical and imaging data from patients who presented as an emergency case with a suspected diagnosis of TIA at a teaching hospital between January 2016 and December 2021 were evaluated. The included 1526 patients were divided into two groups—group 1, with major pathologic vascular findings in the CTA, and group 2, with minor vascular pathologies. Results: Out of 1821 patients with suspected TIA on admission, 1526 met the inclusion criteria. In total, 336 (22%) had major vascular pathologies on CTA, and 1190 (78%) were unremarkable. The majority of patients with major vascular pathologies were male and had a history of arterial hypertension, coronary heart disease, myocardial infarction, ischemic stroke, TIA, atherosclerotic peripheral vascular disease, smoking, antiplatelet medication, had a lower duration of TIA symptoms, and had lower ABCD2 scores. Conclusions: We were able to demonstrate a direct correlation between major CTA pathologies and a history of smoking, age, hyperlipidemia, history of peripheral arterial disease, and a history of stroke and TIA. We were able to prove that the ABCD2 score is even reciprocal to CTA pathology. This means that TIA patients without described risk factors do not immediately require a CTA and could be clarified in the course of treatment with ultrasound or MRI.

Benefit of Intravenous Alteplase Before Thrombectomy Depends on ASPECTS

PURPOSE

Baseline variables could be used to guide the administration of additional intravenous alteplase (IVT) before mechanical thrombectomy (MT). The aim of this study was to determine how baseline imaging and demographic parameters modify the effect of IVT on clinical outcomes in patients with ischemic stroke due to large vessel occlusion.

METHODS

Multicenter retrospective cohort study of ischemic stroke patients triaged by multimodal-CT undergoing MT treatment after direct admission to an MT-eligible center. Inverse-probability weighting analysis (IPW) was used to assess the treatment effect of IVT adjusted for baseline variables. Multivariable logistic regression analysis with IPW-weighting and interaction terms for IVT was performed to predict functional independence (mRS 0-2 at 90-days).

RESULTS

720 patients were included, of which 366 (51%) received IVT. In IPW, the treatment effect of IVT on outcome (mRS 0-2) distinctively varied according to the ASPECTS subgroup (ASPECTS 9-10: +15%, ASPECTS 6-8: +7%, ASPECTS <6: -11%). In multivariable logistic regression analysis, IVT was independently associated with functional independence (aOR: 1.57, 95%CI: 1.16-2.14, p=0.003) and the interaction term was significant for ASPECTS and IVT revealing that IVT was only significantly associated with better outcomes in patients with higher ASPECTS. No other significant baseline variable interaction terms were identified.

INTERPRETATION

ASPECTS was the only baseline variable that showed a significant interaction with IVT for outcome prediction. The application of IVT in patients with an ASPECTS of <6 might have detrimental effects on outcome and may only be considered carefully. This article is protected by copyright. All rights reserved.

Comparison of Different Dosages of Alteplase in Atrial Fibrillation-Related Acute Ischemic Stroke After Intravenous Thrombolysis: A Nationwide, Multicenter, Prospective Cohort Study in Taiwan

Background

Insufficient evidence is available for patients with acute ischemic stroke with atrial fibrillation (AF) to determine the efficacy and safety of different dosages of intravenous thrombolysis treatment. This study examined clinical outcomes in Chinese patients with stroke with and without AF after intravenous thrombolysis treatment with different intravenous thrombolysis doses.

Methods and Results

This multicenter, prospective cohort study recruited 2351 patients with acute ischemic stroke (1371 with AF and 980 without AF) treated with intravenous thrombolysis using alteplase. The Totaled Health Risks in Vascular Events score is a validated risk‐scoring tool used for assessing patients with acute ischemic stroke with and without AF. We evaluated favorable functional outcome at day 90 and symptomatic intracranial hemorrhage within 24 to 36 hours and outcomes of the patients receiving different doses of alteplase. Compared with the non‐AF group, the AF group exhibited a 2‐ to 3‐fold increased risk of symptomatic intracranial hemorrhage according to the National Institute of Neurological Disorders and Stroke standard (relative risk [RR], 2.10 [95% CI, 1.35–3.26]). Favorable functional outcome at 90 days and symptomatic intracranial hemorrhage rates according to the European Cooperative Acute Stroke Study II and the Safe Implementation of Thrombolysis in Stroke‐Monitoring Study standards did not significantly differ between the AF and non‐AF groups. In addition, the low‐dose alteplase subgroup exhibited an increased risk of symptomatic intracranial hemorrhage according to the National Institute of Neurological Disorders and Stroke standard (RR, 2.84 [95% CI, 1.63–4.96]). A validation study confirmed these findings after adjustment for scores determined using different stroke risk‐scoring tools.

Conclusions

Different alteplase dosages did not affect functional status at 90 days in the AF and non‐AF groups. Thus, the adoption of low‐dose alteplase simply because of AF is not recommended.

Value of pre-intervention CT perfusion imaging in acute ischemic stroke prognosis

Noninvasive imaging plays an important role in acute stroke towards diagnosis and ongoing management of patients. Systemic thrombolysis and endovascular thrombectomy (EVT) are proven treatments currently used in standards of care in acute stroke settings. The role of computed tomography angiography (CTA) in selecting patients with large vessel occlusion for EVT is well established. However, the value of CT perfusion (CTP) imaging in predicting outcomes after stroke remains ambiguous. This article critically evaluates the value of multimodal CT imaging in early diagnosis and prognosis of acute ischemic stroke with a focus on the role of CTP in delineating tissue characteristics, patient selection, and outcomes after reperfusion therapy. Insights on various technical and clinical considerations relevant to CTP applications in acute ischemic stroke, recommendations for existing workflow, and future areas of research are discussed.

Intra- and inter-rater consistency of dual assessment by radiologist and neurologist for evaluating DWI-ASPECTS in ischemic stroke

OBJECTIVES

To estimate the intra -and inter-rater consistency of radiologist and neurologist working in pairs attributing DWI-ASPECTS (Diffusion Alberta Stroke Program Early CT Score) in patients with acute middle cerebral artery ischemic stroke referred for mechanical thrombectomy, intravenous thrombolysis or bridging therapy.

METHODS

Five neurologists and 5 radiologists working in pairs and in hour period scored independently and in two reading sessions anonymized DWI-ASPECTS of 80 patients presenting with acute anterior ischaemic stroke in our center. We measured agreement between pairs using intraclass correlation coefficients (ICCs). A Fleiss kappa was used for dichotomized (0-6;7-10) and trichotomized (0-3;4-6;7-10) ASPECTS. The interrater distribution of the score in the trichotomized (0-3;4-6;7-10) ASPECTS was calculated. We determined the interrater (Cohen kappa) and intrarater (Fleiss kappa) agreement on the ASPECTS regions.

RESULTS

The average DWI-ASPECTS was 6.35 (SD±2.44) for the first reading, and 6.47 (SD±2.44) for the second one. The ICC was 0.853 (95%CI, 0.798-0.896) for the interrater, and 0.862 (95%CI, 0.834-0.885) for the intrarater evaluation. Kappa coefficients were high for dichotomized (k=0.75) and trichotomized (k=0.64) ASPECTS. Evaluators agreement on the ASPECTS category (0-3), (4-6) and (7-10) was 88, 76 and 93% respectively. The anatomic region infarcted was well identified (k=0.70-0.77), except for the internal capsula (k=0.57). Interrater agreement was fair for M5 (k=0.37), moderate for internal capsula (0.52) and substantial for the other regions (0.60-0.79).

CONCLUSIONS

Reliability of DWI-ASPECTS is good when determined by radiologist and neurologist working in pairs, which corresponds to our current clinical practice. However, discrepancies are possible for cut-off determination, which may impact the indication of thrombectomy, and for the determination of the exact infarcted region. Agreement to propose category (4-6) is lower than for (0-3) and (8-10) ASPECTS categories.

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.

Evaluation of analytic and clinical performance of thrombin-antithrombin complex and D-dimer assay in prognosis of acute ischemic stroke

: To evaluate analytic and clinical performance of plasma thrombin-antithrombin complex (TAT) and D-dimer assay in assessing the severity and outcome of acute ischemic stroke. The prospective study was conducted and extended from January 2018 to December 2018. A total of 236 patients admitted within 24 h after neurologic symptoms onset were recruited. The median TAT and D-dimer levels were significantly higher in the acute ischemic stroke patients than in the controls. The average TAT levels in patients with mild, moderately severe and severe stroke were 1.75 [interquartile ranges (IQR), 1.1-2.6], 3.3 (IQR, 1.8-4.5) and 13.5 (IQR, 7.2-15.3) ng/ml. The D-dimer levels of respective patient groups were 0.39 (IQR, 0.22-0.73), 0.58 (IQR, 0.39-1.25) and 3.59 (IQR, 1.73-4.74) mg/l. With the optimal cut-off TAT level (1.75 ng/ml) determined from receiver operating characteristic analysis, the Area under the curve (AUC), the sensitivity and specificity of TAT for stroke diagnosis were 0.763, 58.1 and 87.8%. The cut-off D-dimer level was 0.38 mg/l and the AUC, the sensitivity and specificity were 0.772, 60.2 and 88.9%. The Area under the receiver operating characteristic curves (AUROCs) and sensitivity in the moderate to severe stroke increased to 0.903 and 86.9% for TAT, and 0.880 and 80.3% for D-dimer, respectively. Age and high TAT level were significant independent risk factors for stroke severity. Age, high initial National Institutes of Health Stroke Scale score and high TAT level were significant independent poor prognostic factors on multivariate analysis. TAT and D-dimer were superior in separating the moderate-to-severe stroke than mild stroke. A high TAT plasma level is an independent predictor for stroke severity and poor prognosis during 1-month follow-up.

Diagnosis and Management of Transient Ischemic Attack and Acute Ischemic Stroke: A Review

IMPORTANCE

Stroke is the fifth leading cause of death and a leading cause of disability in the United States, affecting nearly 800 000 individuals annually.

OBSERVATIONS

Sudden neurologic dysfunction caused by focal brain ischemia with imaging evidence of acute infarction defines acute ischemic stroke (AIS), while an ischemic episode with neurologic deficits but without acute infarction defines transient ischemic attack (TIA). An estimated 7.5% to 17.4% of patients with TIA will have a stroke in the next 3 months. Patients presenting with nondisabling AIS or high-risk TIA (defined as a score ≥4 on the age, blood pressure, clinical symptoms, duration, diabetes [ABCD2] instrument; range, 0-7 [7 indicating worst stroke risk]), who do not have severe carotid stenosis or atrial fibrillation, should receive dual antiplatelet therapy with aspirin and clopidigrel within 24 hours of presentation. Subsequently, combined aspirin and clopidigrel for 3 weeks followed by single antiplatelet therapy reduces stroke risk from 7.8% to 5.2% (hazard ratio, 0.66 [95% CI, 0.56-0.77]). Patients with symptomatic carotid stenosis should receive carotid revascularization and single antiplatelet therapy, and those with atrial fibrillation should receive anticoagulation. In patients presenting with AIS and disabling deficits interfering with activities of daily living, intravenous alteplase improves the likelihood of minimal or no disability by 39% with intravenous recombinant tissue plasminogen activator (IV rtPA) vs 26% with placebo (odds ratio [OR], 1.6 [95% CI, 1.1-2.6]) when administered within 3 hours of presentation and by 35.3% with IV rtPA vs 30.1% with placebo (OR, 1.3 [95% CI, 1.1-1.5]) when administered within 3 to 4.5 hours of presentation. Patients with disabling AIS due to anterior circulation large-vessel occlusions are more likely to be functionally independent when treated with mechanical thrombectomy within 6 hours of presentation vs medical therapy alone (46.0% vs 26.5%; OR, 2.49 [95% CI, 1.76-3.53]) or when treated within 6 to 24 hours after symptom onset if they have a large ratio of ischemic to infarcted tissue on brain magnetic resonance diffusion or computed tomography perfusion imaging (modified Rankin Scale score 0-2: 53% vs 18%; OR, 4.92 [95% CI, 2.87-8.44]).

CONCLUSIONS AND RELEVANCE

Dual antiplatelet therapy initiated within 24 hours of symptom onset and continued for 3 weeks reduces stroke risk in select patients with high-risk TIA and minor stroke. For select patients with disabling AIS, thrombolysis within 4.5 hours and mechanical thrombectomy within 24 hours after symptom onset improves functional outcomes.

European Stroke Organisation (ESO) guidelines on intravenous thrombolysis for acute ischaemic stroke

Intravenous thrombolysis is the only approved systemic reperfusion treatment for patients with acute ischaemic stroke. These European Stroke Organisation (ESO) guidelines provide evidence-based recommendations to assist physicians in their clinical decisions with regard to intravenous thrombolysis for acute ischaemic stroke. These guidelines were developed based on the ESO standard operating procedure and followed the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. The working group identified relevant clinical questions, performed systematic reviews and meta-analyses of the literature, assessed the quality of the available evidence, and wrote recommendations. Expert consensus statements were provided if not enough evidence was available to provide recommendations based on the GRADE approach. We found high quality evidence to recommend intravenous thrombolysis with alteplase to improve functional outcome in patients with acute ischemic stroke within 4.5 h after symptom onset. We also found high quality evidence to recommend intravenous thrombolysis with alteplase in patients with acute ischaemic stroke on awakening from sleep, who were last seen well more than 4.5 h earlier, who have MRI DWI-FLAIR mismatch, and for whom mechanical thrombectomy is not planned. These guidelines provide further recommendations regarding patient subgroups, late time windows, imaging selection strategies, relative and absolute contraindications to alteplase, and tenecteplase. Intravenous thrombolysis remains a cornerstone of acute stroke management. Appropriate patient selection and timely treatment are crucial. Further randomized controlled clinical trials are needed to inform clinical decision-making with regard to tenecteplase and the use of intravenous thrombolysis before mechanical thrombectomy in patients with large vessel occlusion.

Measuring 129 Xe transfer across the blood-brain barrier using MR spectroscopy

PURPOSE

This study develops a tracer kinetic model of xenon uptake in the human brain to determine the transfer rate of inhaled hyperpolarized ¹²⁹ Xe from cerebral blood to gray matter that accounts for the effects of cerebral physiology, perfusion and magnetization dynamics. The ¹²⁹ Xe transfer rate is expressed using a tracer transfer coefficient, which estimates the quantity of hyperpolarized ¹²⁹ Xe dissolved in cerebral blood under exchange with depolarized ¹²⁹ Xe dissolved in gray matter under equilibrium of concentration.

THEORY AND METHODS

Time-resolved MR spectra of hyperpolarized ¹²⁹ Xe dissolved in the human brain were acquired from three healthy volunteers. Acquired spectra were numerically fitted with five Lorentzian peaks in accordance with known ¹²⁹ Xe brain spectral peaks. The signal dynamics of spectral peaks for gray matter and red blood cells were quantified, and correction for the ¹²⁹ Xe T₁ dependence upon blood oxygenation was applied. ¹²⁹ Xe transfer dynamics determined from the ratio of the peaks for gray matter and red blood cells was numerically fitted with the developed tracer kinetic model.

RESULTS

For all the acquired NMR spectra, the developed tracer kinetic model fitted the data with tracer transfer coefficients between 0.1 and 0.14.

CONCLUSION

In this study, a tracer kinetic model was developed and validated that estimates the transfer rate of HP ¹²⁹ Xe from cerebral blood to gray matter in the human brain.

Deciding Thrombolysis in AIS Based on Automated versus on WhatsApp Interpreted ASPECTS, a Reliability and Cost-Effectiveness Analysis in Developing System of Care

Background: Automated ASPECTS has the potential of reducing interobserver variability in the determination of early ischemic changes. We aimed to assess the performance of an automated ASPECTS vs. ASPECTS interpreted for sent CT images on WhatsApp and to correlate these results with the outcome. Materials and Methods: Patients with anterior circulation stroke who had baseline NCCT and underwent successful IV-thrombolysis were included. NCCT-ASPECTS was assessed by two neuroradiologists, and discrepancies were resolved by agreement. Two groups of patients were included; group 1, where treatment was decided after an automated ASPECTS interpretation that was provided by RAPID software, and group 2, where patients received IV-tPA after an assessment of CT images sent on WhatsApp. Results: A total of 122 patients were included: 36 in group 1 and 86 in group 2. In group 2, the interobserver agreement for NCCT ASPECTS was moderate (κ = 0.36), as was the dichotomized data (κ = 0.44). IOA, however, improved (to κ = 0.57 and κ = 0.64) when the same CT images were interpreted on a workstation. In group 1, Automated ASPECTS showed excellent agreement (κ = 0.80) with agreement reads for workstation images. There were significantly (P < 0.001) increased odds of functional independence and fewer hemorrhagic complications with thrombolyzed patients in group 1. Conclusions: Automated ASPECTS provided by the RAPID@IschemaView ASPECTS performs at a level equal to the agreement read of expert neuroradiologists, and this performance was severely degraded when WhatsApp captured CT images used for ASPECTS assessment. In our study, we found that automated ASPECTS might predict outcomes after IV thrombolysis.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

INTERPRETATION

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

Effect of Recanalization on Cerebral Edema in Ischemic Stroke Treated With Thrombolysis and/or Endovascular Therapy

Background and Purpose- A large infarct and expanding cerebral edema (CED) due to a middle cerebral artery occlusion confers a 70% mortality unless treated surgically. Reperfusion may cause blood-brain barrier disruption and a risk for cerebral edema and secondary parenchymal hemorrhage (PH). We aimed to investigate the effect of recanalization on development of early CED and PH after recanalization therapy. Methods- From the SITS-International Stroke Treatment Registry, we selected patients with signs of artery occlusion at baseline (either Hyperdense Artery Sign or computed tomography/magnetic resonance imaging angiographic occlusion). We defined recanalization as the disappearance of radiological signs of occlusion at 22 to 36 hours. Primary outcome was moderate to severe CED and secondary outcome was PH on 22- to 36-hour imaging scans. We used logistic regression with adjustment for baseline variables and PH. Results- Twenty two thousand one hundred eighty-four patients fulfilled the inclusion criteria (n=18 318 received intravenous thrombolysis, n=3071 received intravenous thrombolysis+thrombectomy, n=795 received thrombectomy). Recanalization occurred in 64.1%. Median age was 71 versus 71 years and National Institutes of Health Stroke Scale score 15 versus 16 in the recanalized versus nonrecanalized patients respectively. Recanalized patients had a lower risk for CED (13.0% versus 23.6%), adjusted odds ratio (aOR), 0.52 (95% CI, 0.46-0.59), and a higher risk for PH (8.9% versus 6.5%), adjusted odds ratio, 1.37 (95% CI, 1.22-1.55), than nonrecanalized patients. Conclusions- In patients with acute ischemic stroke, recanalization was associated with a lower risk for early CED even after adjustment for higher rate for PH in recanalized patients.

Cutting Edge Acute Ischemic Stroke Management

Acute ischemic stroke (AIS) is a medical emergency that requires prompt recognition and streamlined work-up to ensure that time-dependent therapies are initiated to achieve the best outcomes. This article discusses frequently missed AIS in the emergency department, the role of various imagining modalities in the work-up of AIS, updates on the use of intravenous thrombolytics and endovascular therapy for AIS, pearls on supportive care management of AIS, and prehospital and hospital process improvements to shorten door-to-needle time.

Detection of early infarction signs with machine learning-based diagnosis by means of the Alberta Stroke Program Early CT score (ASPECTS) in the clinical routine

PURPOSE

New software solutions emerged to support radiologists in image interpretation in acute ischemic stroke. This study aimed to validate the performance of computer-aided assessment of the Alberta Stroke Program Early CT score (ASPECTS) for detecting signs of early infarction.

METHODS

ASPECT scores were assessed in 119 CT scans of patients with acute middle cerebral artery ischemia. Patient collective was differentiated according to (I) normal brain, (II) leukoencephalopathic changes, (III) infarcts, and (IV) atypical parenchymal defects (multiple sclerosis, etc.). ASPECTS assessments were automatically provided by the software package e-ASPECTS (Brainomix®, UK) (A). Subsequently, three neuroradiologists (B), (C), and (D) examined independently 2380 brain regions. Interrater comparison was performed with the definite infarct core as reference standard after best medical care (thrombolysis and/or thrombectomy).

RESULTS

Interrater comparison revealed higher correlation coefficient of (B) 0.71, (C) 0.76, and of (D) 0.80 with definite infarct core compared to (A) 0.59 for ASPECTS assessment in the acute ischemic stroke setting. While (B), (C), and (D) showed a significant correlation for individual patient groups (I), (II), (III), and (IV), except for (D) (II), (A) was not significant in patient groups with pre-existing changes (II), (III), and (IV). The following sensitivities, specificities, PPV, NPV, and accuracies given in percent were achieved: (A) 83, 57, 55, 82, and 67; (B) 74, 76, 69, 83, and 77; (C) 80.8, 85.2, 76, 84, and 80; (D) 63, 90.7, 82, 79, and 80, respectively.

CONCLUSION

For ASPECTS assessment, the examined software may provide valid data in case of normal brain. It may enhance the work of neuroradiologists in clinical decision making. A final human check for plausibility is needed, particularly in patient groups with pre-existing cerebral changes.

Preliminary study of time maximum intensity projection computed tomography imaging for the detection of early ischemic change in patient with acute ischemic stroke

Noncontrast computed tomography (NCCT) has been used for the detection of early ischemic change (EIC); however, correct interpretation of NCCT findings requires much clinical experience. This study aimed to assess the accuracy of time maximum intensity projection computed tomography technique (tMIP), which reflects the maximum value for the time phase direction from the dynamic volume data for each projected plane, for detection of EIC, against that of NCCT.Retrospective review of NCCT, cerebral blood volume in CT perfusion (CTP-CBV), and tMIP of 186 lesions from 280 regions evaluated by Alberta Stroke Program Early CT Score (ASPECTS) in 14 patients with acute middle cerebral artery stroke who had undergone whole-brain CTP using 320-row area detector CT was performed. Four radiologists reviewed EIC on NCCT, CTP-CBV, and tMIP in each ASPECTS region at onset using the continuous certainty factor method. Receiver operating characteristic analysis was performed to compare the relative performance for detection of EIC. The correlations were evaluated.tMIP-color showed the best discriminative value for detection of EIC. There were significant differences in the area under the curve for NCCT and tMIP-color, CTP-CBV (P < .05). Scatter plots of ASPECTS showed a positive significant correlation between NCCT, tMIP-gray, tMIP-color, and the follow-up study (NCCT, r = 0.32, P = .0166; tMIP-gray, r = 0.44, P = .0007; tMIP-color, r = 0.34, P = .0104).Because tMIP provides a high contrast parenchymal image with anatomical and vascular information in 1 sequential scan, it showed greater accuracy for detection of EIC and predicted the final infarct extent more accurately than NCCT based on ASPECTS.

Imaging Human Brain Perfusion with Inhaled Hyperpolarized 129Xe MR Imaging

Purpose To evaluate the feasibility of directly imaging perfusion of human brain tissue by using magnetic resonance (MR) imaging with inhaled hyperpolarized xenon 129 (129Xe). Materials and Methods In vivo imaging with 129Xe was performed in three healthy participants. The combination of a high-yield spin-exchange optical pumping 129Xe polarizer, custom-built radiofrequency coils, and an optimized gradient-echo MR imaging protocol was used to achieve signal sensitivity sufficient to directly image hyperpolarized 129Xe dissolved in the human brain. Conventional T1-weighted proton (hydrogen 1 [1H]) images and perfusion images by using arterial spin labeling were obtained for comparison. Results Images of 129Xe uptake were obtained with a signal-to-noise ratio of 31 ± 9 and demonstrated structural similarities to the gray matter distribution on conventional T1-weighted 1H images and to perfusion images from arterial spin labeling. Conclusion Hyperpolarized 129Xe MR imaging is an injection-free means of imaging the perfusion of cerebral tissue. The proposed method images the uptake of inhaled xenon gas to the extravascular brain tissue compartment across the intact blood-brain barrier. This level of sensitivity is not readily available with contemporary MR imaging methods. ©RSNA, 2017.

Reperfusion therapy in acute ischemic stroke: dawn of a new era?

Following the success of recent endovascular trials, endovascular therapy has emerged as an exciting addition to the arsenal of clinical management of patients with acute ischemic stroke (AIS). In this paper, we present an extensive overview of intravenous and endovascular reperfusion strategies, recent advances in AIS neurointervention, limitations of various treatment paradigms, and provide insights on imaging-guided reperfusion therapies. A roadmap for imaging guided reperfusion treatment workflow in AIS is also proposed. Both systemic thrombolysis and endovascular treatment have been incorporated into the standard of care in stroke therapy. Further research on advanced imaging-based approaches to select appropriate patients, may widen the time-window for patient selection and would contribute immensely to early thrombolytic strategies, better recanalization rates, and improved clinical outcomes.

Imaging assessment of acute ischaemic stroke: a review of radiological methods

Acute ischaemic stroke is the second largest cause of death worldwide and a cause of major physical and psychological morbidity. Current evidence based treatment includes intravenous thrombolysis (IVT) and mechanical thrombectomy (MT), both requiring careful patient selection and to be administered as quickly as possible within a limited time window from symptom onset. Imaging plays a crucial role identifying patients who may benefit from MT or IVT whilst excluding those that may be harmed. For IVT, imaging must as a minimum exclude haemorrhage, stroke mimics and provide an estimate of non-viable brain. For MT, imaging must in addition detect and characterize intra-arterial thrombus and assess the intra and extracranial arterial architecture. More advanced imaging techniques may be used to assess more accurately the volume of non-viable and potentially salvageable brain tissue. It is highly likely that further research will identify patients who would benefit from treatment beyond currently accepted time windows for IVT (4.5 h) and MT (6 h) and patients with an unknown time of symptom onset. Current evidence indicates that best outcomes are achieved when treatment is instituted as soon as possible after symptom onset. A rapid, efficient imaging pathway including interpretation is fundamental to achieving the best outcomes. This review summarizes current techniques for imaging assessment of acute stroke, highlighting strengths and limitations of each. The optimum pathway is a balance between diagnostic information, local resources, specialization and the time taken to acquire, process and interpret the data. As new evidence emerges, it is likely that the minimum required imaging data will change.

Predictors for Cerebral Edema in Acute Ischemic Stroke Treated With Intravenous Thrombolysis

BACKGROUND AND PURPOSE

Cerebral edema (CED) is a severe complication of acute ischemic stroke. There is uncertainty regarding the predictors for the development of CED after cerebral infarction. We aimed to determine which baseline clinical and radiological parameters predict development of CED in patients treated with intravenous thrombolysis.

METHODS

We used an image-based classification of CED with 3 degrees of severity (less severe CED 1 and most severe CED 3) on postintravenous thrombolysis imaging scans. We extracted data from 42 187 patients recorded in the SITS International Register (Safe Implementation of Treatments in Stroke) during 2002 to 2011. We did univariate comparisons of baseline data between patients with or without CED. We used backward logistic regression to select a set of predictors for each CED severity.

RESULTS

CED was detected in 9579/42 187 patients (22.7%: 12.5% CED 1, 4.9% CED 2, 5.3% CED 3). In patients with CED versus no CED, the baseline National Institutes of Health Stroke Scale score was higher (17 versus 10; P<0.001), signs of acute infarct was more common (27.9% versus 19.2%; P<0.001), hyperdense artery sign was more common (37.6% versus 14.6%; P<0.001), and blood glucose was higher (6.8 versus 6.4 mmol/L; P<0.001). Baseline National Institutes of Health Stroke Scale, hyperdense artery sign, blood glucose, impaired consciousness, and signs of acute infarct on imaging were independent predictors for all edema types.

CONCLUSIONS

The most important baseline predictors for early CED are National Institutes of Health Stroke Scale, hyperdense artery sign, higher blood glucose, decreased level of consciousness, and signs of infarct at baseline. The findings can be used to improve selection and monitoring of patients for drug or surgical treatment.

A multiparameter model predicting in-hospital mortality in malignant cerebral infarction

The early identification of patients with large hemisphere infarctions (LHIs) at risk of fatal brain edema may result in better outcomes. A quantitative model using parameters obtained at admission may be a predictor of in-hospital mortality from LHI.This prospective study enrolled all patients with LHI involving >50% of the middle cerebral artery (MCA) admitted to our neurological intensive care unit within 48 hours of symptom onset. Early clinical and radiographic parameters and the baseline CHADS2 score (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, stroke [double weight]) were analyzed regarding their ability to predict patient outcomes.Seventy-seven patients with LHIs were identified, 33 (42.9%) with complete MCA infarction (CMCA), and 44 (57.1%) with incomplete MCA infarction (IMCA). The predictors of CMCA score included: >1/3 early hypodensity in computed tomography findings, hyperdense MCA sign, brain edema, initial National Institutes of Health Stroke Scale (NIHSS) score ≥17, and stroke in progression during the 1st 5 days of admission. The cutoff CMCA score was 2, with a sensitivity of 81.8% and specificity of 70.5%. Mortality score 1, used for predicting in-hospital mortality from LHI, included CMCA and CHADS2 scores ≥4 (sensitivity 100.0%, specificity 57.4%), and mortality score 2 included CMCA and CHADS2 scores ≥4, and NIHSS score ≥26, during the 1st 5 days (sensitivity 100.0%, specificity 91.7%).Patients qualifying for a mortality score of 2 were at high-risk of in-hospital mortality from LHI. These findings may aid in identifying patients who may benefit from invasive therapeutic strategies, and in better describing the characteristics of those at risk of mortality.

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.

Alberta Stroke Program Early CT Score in the Prognostication after Endovascular Treatment for Ischemic Stroke: A Meta-analysis

Purpose

The Alberta Stroke Program Early CT Score (ASPECTS) was devised to quantify the extent of early ischemic changes in the middle cerebral artery territory on brain CT. We performed a systematic review and meta-analysis of studies that presented clinical outcomes and baseline ASPECTS in ischemic stroke patients managed with endovascular methods to validate the use of ASPECTS for risk prognostication.

Materials and Methods

We searched the MEDLINE, EMBASE, and Cochran databases for observational or interventional studies that reported clinical outcomes and baseline ASPECTS in ischemic stroke patients treated with endovascular methods. Data were pooled to perform a meta-analysis for comparisons of clinical outcomes between high and low ASPECTS patients.

Results

A meta-analysis of 13 studies (six observational and seven interventional) revealed favorable outcomes (mRS sore 0-2 at 90 days) for high baseline ASPECTS (odds ratio=2.22; 95% CI: 1.74-2.86).

Conclusion

High ASPECTS is a predictor of favorable outcome after endovascular therapy for ischemic stroke.

CT of the head for acute stroke: Diagnostic performance of a tablet computer prior to intravenous thrombolysis

INTRODUCTION

The authors propose that tablet computers could benefit patients with acute stroke in the remote care setting, where time to and accuracy of CT interpretation greatly influences patient outcome.

METHODS

One hundred and fifty consecutive patients who presented to the Emergency Department of a tertiary referral neurosciences centre within a time window suitable for intravenous thrombolytic therapy were included. Images were wirelessly transmitted to a tablet computer (iPad 3rd Generation, model = A1430, Apple, Cupertino, CA) and were reviewed by radiologists with three levels of experience for signs of intracranial haemorrhage, large vessel occlusion and parenchymal infarction. Reference standard interpretation was performed by two neuroradiologists using a diagnostic monochrome display.

RESULTS

Consensus neuroradiologist review on the tablet display found and correctly classified all of the 23 cases of intracranial haemorrhage including 21 cases of parenchymal haematoma, two cases of petechial haemorrhage and one patient with an acute subdural haematoma. Less experienced readers missed cases of petechial and subdural haematomas. There was excellent agreement between the tablet and diagnostic monochrome display in cases with no infarct or extensive parenchymal infarction.

CONCLUSIONS

Tablet computers can be used to facilitate rapid preliminary CT interpretation in patients with acute stroke in the remote setting.

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.

CT imaging selection in acute stroke

Acute stroke has become an increasingly treatable cause of acute neurological deficits. Indeed, over the last two decades, the introduction of first thrombolysis, and now thrombectomy has improved patient outcomes and extended the therapeutic window. Computed tomography has been established as the most simple and readily available technique for the diagnosis and management of patients with acute stroke. Indeed, CT allows easy confirmation or exclusion of acute hemorrhage on the one hand, and on the other hand the early signs are quite reliable in the detection of ischemia. In the early phase the clot can be seen as well as exchanges related to early changes in water concentration in ischemia and the surrounding penumbra. Additional techniques such as angio-CT show the location of the clot and perfusion techniques reveal local hemodynamics as well as potential tissue viability. Newer techniques such as double energy CT and late phase CT should provide information on collateral flow as well as on the presence of early hemorrhagic transformation. All these techniques should thus make available new information on tissue viability,that is indispensable in the choice of revascularization technique. Thus CT techniques allow a quick and reliable triage as well as a finer characterization of the ischemic process. The use of all these CT techniques in an optimal way should help improve patient triage and selection of the most adequate treatment with further improvements in clinical outcomes as a result.

Topographic Assessment of Acute Ischemic Changes for Prognostication of Anterior Circulation Stroke

BACKGROUND

The location of acute ischemic infarct can affect the clinical outcome of stroke patients. We aimed to develop a prognostic tool based on the topographic distribution of early ischemic changes on admission computed tomography (CT) scans.

METHODS

Using the albumin in acute stroke (ALIAS) trials dataset, patients with anterior circulation stroke were included for analysis. A 3-month modified Rankin scale (mRs) score > 2 defined disability/death; and ≤2 defined favorable outcome. A penalized logistic regression determined independent predictors of disability/death among components of admission CT scan Alberta Stroke Program Early CT score (ASPECTS). Follow-up 24-hour CT/MRI scans were reviewed for intracranial hemorrhage (ICH).

RESULTS

A simplified ASPECTS (sASPECTS) was developed including the caudate, lentiform nucleus, insula, and M5 components of ASPECTS-which were independent predictors of disability/death on multivariate analysis. There was no significant difference between ASPECTS and sASPECTS in prediction of disability/death (P = .738). Among patients with sASPECTS ≥ 1, the rate of favorable outcome was higher in those with intravenous (IV) thrombolytic therapy (501/837, 59.9%) versus those without treatment (91/183, 49.7%, P = .013); whereas among patients with sASPECTS of 0, IV thrombolysis was not associated with improved outcome. Also, patients with sASPECTS of 0 were more likely to develop symptomatic ICH (odds ratio = 2.62, 95% confidence interval: 1.49-4.62), compared to those with sASPECTS ≥ 1 (P = .004).

CONCLUSIONS

Topographic assessment of acute ischemic changes using the sASPECTS (including caudate, lentiform nucleus, insula, and M5) can predict disability/death in anterior circulation stroke as accurately as the ASPECTS; and may help predict response to treatment and risk of developing symptomatic ICH.

Intra-individual diagnostic image quality and organ-specific-radiation dose comparison between spiral cCT with iterative image reconstruction and z-axis automated tube current modulation and sequential cCT

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Superiority of spiral versus sequential cCT in image quality and organ-specific-radiation dose.

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Spiral cCT: lower organ-specific-radiation-dose in eye lense compared to tilted sequential cCT.

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State-of-the-art IR spiral cCT techniques has significant advantages over sequential cCT techniques.

Objectives

To prospectively evaluate image quality and organ-specific-radiation dose of spiral cranial CT (cCT) combined with automated tube current modulation (ATCM) and iterative image reconstruction (IR) in comparison to sequential tilted cCT reconstructed with filtered back projection (FBP) without ATCM.

Methods

31 patients with a previous performed tilted non-contrast enhanced sequential cCT aquisition on a 4-slice CT system with only FBP reconstruction and no ATCM were prospectively enrolled in this study for a clinical indicated cCT scan. All spiral cCT examinations were performed on a 3rd generation dual-source CT system using ATCM in z-axis direction. Images were reconstructed using both, FBP and IR (level 1–5). A Monte-Carlo-simulation-based analysis was used to compare organ-specific-radiation dose. Subjective image quality for various anatomic structures was evaluated using a 4-point Likert-scale and objective image quality was evaluated by comparing signal-to-noise ratios (SNR).

Results

Spiral cCT led to a significantly lower (p < 0.05) organ-specific-radiation dose in all targets including eye lense. Subjective image quality of spiral cCT datasets with an IR reconstruction level 5 was rated significantly higher compared to the sequential cCT acquisitions (p < 0.0001). Consecutive mean SNR was significantly higher in all spiral datasets (FBP, IR 1–5) when compared to sequential cCT with a mean SNR improvement of 44.77% (p < 0.0001).

Conclusions

Spiral cCT combined with ATCM and IR allows for significant-radiation dose reduction including a reduce eye lens organ-dose when compared to a tilted sequential cCT while improving subjective and objective image quality.

A Quantitative Method Using Head Noncontrast CT Scans to Detect Hyperacute Nonvisible Ischemic Changes in Patients With Stroke

PURPOSE

Because clinical evaluation of noncontrast computed tomography (CT) has a poor sensitivity in the evaluation of acute ischemic stroke, computer-aided diagnosis may be able to facilitate the performance. Recently, we introduced a computational method for the detection and localization of visible infarcts. Herein, we aimed to evaluate and extend a previous method, the Stroke Imaging Marker (SIM), to localize nonvisible hyperacute ischemia.

MATERIALS AND METHODS

On the basis of the SIM and its components-the ratio of percentile differences in subranges of Hounsfield Unit (HU) distribution (P-ratio), ratio of voxels count in ranges of brain CT intensity, median HU attenuation value-the infarct localization was performed in 140 early and follow-up scans of 70 patients. In none of the early scans was the infarct visible to a radiologist or an experienced stroke neuroradiologist. The infarcted hemisphere detection rate (HDR) and sensitivity of infarct localization were measured by overlapping the region of detected tissue in the initial scan, with the gold standard set for the fully visible stroke in the follow-up scan.

RESULTS

The best performance of the algorithm was found for the P-ratio including seven percentile subranges within the range of 35th-75th percentile. The modified SIM provided a 76% ischemic HDR and 54% sensitivity in spatial localization of hyperacute ischemia (68% among properly detected infarct sides).

CONCLUSION

The improved SIM is a dedicated and potentially useful tool for hyperacute nonvisible brain infarct detection from CT scans and may contribute to reduction of image-to-needle time in patients eligible for revascularization therapy.