ASPECTS CT in Acute Ischemia: Review of Current Data

Dual-Energy CT in Acute Stroke: Could Non-Contrast CT Be Replaced by Virtual Non-Contrast CT? A Feasibility Study

Purpose: We aimed to evaluate whether virtual non-contrast cerebral computed tomography (VNCCT) reconstructed from intravenous contrast-enhanced dual-energy CT (iv-DECT) could replace non-contrast CT (NCCT) in patients with suspected acute cerebral ischemia. Method: This retrospective study included all consecutive patients in whom NCCT followed by iv-DECT were performed for suspected acute ischemia in our emergency department over a 1-month period. The Alberta Stroke Program Early CT Score (ASPECTS) was used to determine signs of acute ischemia in the anterior and posterior circulation, the presence of hemorrhage, and alternative findings, which were randomly evaluated via the consensus reading of NCCT and VNCCT by two readers blinded to the final diagnosis. An intraclass correlation between VNCCT and NCCT was calculated for the ASPECTS values. Both techniques were evaluated for their ability to detect ischemic lesions (ASPECTS <10) when compared with the final discharge diagnosis (reference standard). Results: Overall, 148 patients (80 men, mean age 64 years) were included, of whom 46 (30%) presented with acute ischemia, 6 (4%) presented with intracerebral hemorrhage, 11 (7%) had an alternative diagnosis, and 85 (59%) had no pathological findings. The intraclass correlation coefficients of the two modalities were 0.97 (0.96-0.98) for the anterior circulation and 0.77 (0.69-0.83) for the posterior circulation. The VNCCT's sensitivity for detecting acute ischemia was higher (41%, 19/46) than that of NCCT (33%, 15/46). Specificity was similar between the two techniques, at 94% (97/103) and 98% (101/103), respectively. Conclusions: Our results show that VNCCT achieved a similar diagnostic performance as NCCT and could, thus, replace NCCT in assessing patients with suspected acute cerebral ischemia.

The essential role of neuroimaging in diagnosing and managing cerebrovascular disease in Africa: a review

BACKGROUND

Cerebrovascular disease is a significant cause of morbidity and mortality in Africa, and using neuroimaging techniques has improved the diagnosis and management of this disease. However, there is a lack of comprehensive reviews of the role and effectiveness of neuroimaging techniques in the African context.

METHODS

We reviewed the literature to evaluate the role of neuroimaging in diagnosing and managing cerebrovascular disease in Africa. Our search included electronic databases such as PubMed, Scopus, and Google Scholar from 2000 to April 2023. We included peer-reviewed studies written in English that reported on the use of neuroimaging in diagnosing and managing cerebrovascular disease in African populations. We excluded non-peer-reviewed articles, letters, editorials, and studies unrelated to cerebrovascular disease, neuroimaging, or Africa. A total of 102 potential articles were identified; after applying our exclusion criteria and removing duplicated articles, 51 articles were reviewed.

RESULTS

Our findings suggest that neuroimaging techniques such as CT, MRI, and Skull x-ray play a crucial role in diagnosing and managing cerebrovascular disease in Africa. CT and MRI were the most commonly used techniques, with CT being more widely available and less expensive than MRI. However, challenges to using neuroimaging in Africa include the high cost of equipment and maintenance, lack of trained personnel, and inadequate infrastructure. These challenges limit the widespread use of neuroimaging in diagnosing and managing cerebrovascular disease in Africa.

CONCLUSION

Neuroimaging techniques are essential for diagnosing and managing cerebrovascular disease in Africa, but challenges to their use must be addressed to improve healthcare outcomes. Our policy recommendations can help improve the availability and accessibility of neuroimaging services in Africa.

Validation of two automated ASPECTS software on non-contrast computed tomography scans of patients with acute ischemic stroke

Purpose

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) was designed for semi-quantitative assessment of early ischemic changes on non-contrast computed tomography (NCCT) for acute ischemic stroke (AIS). We evaluated two automated ASPECTS software in comparison with reference standard.

Methods

NCCT of 276 AIS patients were retrospectively reviewed (March 2018–June 2020). A three-radiologist consensus for ASPECTS was used as reference standard. Imaging data from both baseline and follow-up were evaluated for reference standard. Automated ASPECTS were calculated from baseline NCCT with 1-mm and 5-mm slice thickness, respectively. Agreement between automated ASPECTS and reference standard was assessed using intra-class correlation coefficient (ICC). Correlation of automated ASPECTS with baseline stroke severity (NIHSS) and follow-up ASPECTS were evaluated using Spearman correlation analysis.

Results

In score-based analysis, automated ASPECTS calculated from 5-mm slice thickness images agreed well with reference standard (software A: ICC = 0.77; software B: ICC = 0.65). Bland–Altman analysis revealed that the mean differences between automated ASPECTS and reference standard were ≤ 0.6. In region-based analysis, automated ASPECTS derived from 5-mm slice thickness images by software A showed higher sensitivity (0.60 vs. 0.54), lower specificity (0.91 vs. 0.94), and higher AUC (0.76 vs. 0.74) than those using 1-mm slice thickness images (p &lt; 0.05). Automated ASPECTS derived from 5-mm slice thickness images by software B showed higher sensitivity (0.56 vs. 0.51), higher specificity (0.87 vs. 0.81), higher accuracy (0.80 vs. 0.73), and higher AUC (0.71 vs. 0.66) than those using 1-mm slice thickness images (p &lt; 0.05). Automated ASPECTS were significantly associated with baseline NIHSS and follow-up ASPECTS.

Conclusion

Automated ASPECTS showed good reliability and 5 mm was the optimal slice thickness.

Post-stroke Chorea in the Neurology Department of Ignace Deen Hospital of Conakry, Guinea

INTRODUCTION

Chorea is an uncommon complication of stroke. The pathophysiology, the exact location of the lesions, and the evolution of this type of chorea are still poorly understood. The objective was to describe the epidemiological, clinical, and imaging profile of post-stroke chorea in a tropical environment in the context of a stroke epidemic.

MATERIAL AND METHODS

We conducted a five-year retrospective observational study from 2015 to 2020 on stroke patients who presented with chorea in our department. Epidemiological, clinical, and imaging data were registered.

RESULTS

Fourteen patients presented with chorea after their stroke, a frequency of 0.6%. The average age was 57.1 years with a male predominance. Hypertension was the cardiovascular risk factor in half of the patients; three patients (21.4) were diabetic. Chorea was the initial manifestation of the stroke in eight patients (57.1%). Thirteen patients (92.9%) had an ischaemic stroke and one had a cerebral haemorrhage. The middle cerebral artery (MCA) was involved in nine patients (64.3%), the anterior cerebral artery (ACA) in three patients (21.4%), and two patients (14.3%) had posterior cerebral artery (PCA) involvement. The lesions were cortical in five patients (35.7%), five other patients (35.7%) had a deep location, and four patients (28.6%) had both deep and cortical locations of their lesions. The structures affected were the lentiform nucleus (50%), the insula (35.7%), the caudate nucleus (14.3%), and the thalamus (14.3%).

CONCLUSION

Post-stroke chorea is poorly studied in the tropics. In the presence of any acute abnormal movement associated with cardiovascular risk factors, post-stroke chorea should be considered. Recovery is rapid when treated early.

Deep Learning in Ischemic Stroke Imaging Analysis: A Comprehensive Review

Ischemic stroke is a cerebrovascular disease with a high morbidity and mortality rate, which poses a serious challenge to human health and life. Meanwhile, the management of ischemic stroke remains highly dependent on manual visual analysis of noncontrast computed tomography (CT) or magnetic resonance imaging (MRI). However, artifacts and noise of the equipment as well as the radiologist experience play a significant role on diagnostic accuracy. To overcome these defects, the number of computer-aided diagnostic (CAD) methods for ischemic stroke is increasing substantially during the past decade. Particularly, deep learning models with massive data learning capabilities are recognized as powerful auxiliary tools for the acute intervention and guiding prognosis of ischemic stroke. To select appropriate interventions, facilitate clinical practice, and improve the clinical outcomes of patients, this review firstly surveys the current state-of-the-art deep learning technology. Then, we summarized the major applications in acute ischemic stroke imaging, particularly in exploring the potential function of stroke diagnosis and multimodal prognostication. Finally, we sketched out the current problems and prospects.

Association between Early Ischemic Changes and Collaterals in Acute Stroke: A Retrospective Study

BACKGROUND AND PURPOSE

The quality of leptomeningeal collaterals may influence the speed of infarct progression in acute stroke. Our main objective was to evaluate the association of leptomeningeal collateral score and its interaction with time with ischemic changes on CT in patients with acute stroke.

MATERIALS AND METHODS

Adult patients with acute stroke symptoms and anterior circulation large-vessel occlusion on CTA from 2015 to 2019 were included. Routinely performed NCCT and multiphase CTA were reviewed to assess ASPECTS and the leptomeningeal collateral score. We built multivariate regression models to assess the association between leptomeningeal collateral score and its interaction with time and ASPECTS. Performance measures to predict poor ASPECTS at different time thresholds (identified with receiver operating characteristic curve analysis) were estimated in a subgroup of patients with poor leptomeningeal collateral scores.

RESULTS

Leptomeningeal collateral scores 0-1 were associated with lower ASPECTS, and the model with dichotomized and trichotomized leptomeningeal collateral score showed a significant multiplicative interaction between time and the leptomeningeal collateral score. The negative predictive value for poor ASPECTS was >0.9 for at least the first 3 hours from stroke onset to imaging, and the positive predictive value was <0.5 for every time threshold tested in the subgroup of patients with leptomeningeal collateral scores 0-3.

CONCLUSIONS

Poor (0-1) leptomeningeal collateral scores were associated with lower ASPECTS, and an increase in time has a multiplicative interaction with the leptomeningeal collateral score on ASPECTS.

Serial ASPECTS in the DAWN Trial: Infarct Evolution and Clinical Impact

BACKGROUND AND PURPOSE

The impact of baseline ischemia on Alberta Stroke Program Early CT Score (ASPECTS) and evolution over 24 hours may be distinct in late thrombectomy. We analyzed predictors of serial ASPECTS and clinical outcomes in the DAWN trial (Diffusion-Weighted Imaging or CTP Assessment With Clinical Mismatch in the Triage of Wake-Up and Late Presenting Strokes Undergoing Neurointervention With Trevo).

METHODS

The DAWN Imaging Core Laboratory independently scored ASPECTS at baseline and 24 hours. Descriptive statistics characterized ASPECTS on computed tomography/magnetic resonance imaging at baseline and 24 hours, delineating ASPECTS change over 24 hours.

RESULTS

206 subjects (mean age 70.0±13.7 years; 54.9% (n=113) female; baseline National Institutes of Health Stroke Scale median (interquartile range) 17 (13, 21) were included. Baseline ASPECTS was median (interquartile range) 8.0 (7-8), with 92/205 (44.9%) between 0 and 7 and 113/205 (55.1%) 8 and 10. 24-hour ASPECTS was median 6.0 (4-8), with ASPECTS change or infarct evolution having median -1, ranging from -8 to +2. Multivariable logistic regression showed older age (odds ratio [OR] for 10-year interval, 1.26 [95% CI, 1.02-1.55], P=0.030) and dyslipidemia (OR, 1.84 [95% CI, 1.06-3.19], P=0.031) were independently associated with higher baseline ASPECTS. Higher 24-hour ASPECTS was predicted by endovascular treatment (OR, 2.76 [95% CI, 1.58-4.81], P=0.0004), baseline glucose <150 mg/dL (OR, 2.86 [95% CI, 1.50-5.46], P=0.001), lower baseline National Institutes of Health Stroke Scale (OR, 0.93 [95% CI, 0.89-0.98], P=0.010), and older age (OR for 10-year interval, 1.25 [95% CI, 1.01-1.55], P=0.041). Internal carotid artery lesion location (OR, 0.47 [95% CI, 0.24-0.89], P=0.021) was inversely related to 24-hour ASPECTS. Good clinical outcome (day 90 modified Rankin Scale score 0-2) was predicted by 24-hour ASPECTS (OR, 1.46 [95% CI, 1.08-1.96], P=0.014). Extensive infarct evolution (ASPECTS decrease ≥6) occurred in 14/201 (7.0%). Elevated baseline serum glucose ≥150 mg/dL was a predictor of ASPECTS decrease of ≥4 points (OR, 2.78 [95% CI, 1.21-6.35] P=0.016) as was internal carotid artery occlusion (OR, 2.49 [95% CI, 1.05-5.88]; P=0.038). ASPECTS change was influenced by treatment arm (P=0.001 by Wilcoxon), including 0 ASPECTS change in 42/105 (40.0%) of the endovascular arm and only 20/96 (20.8%) of the medical arm.

CONCLUSIONS

DAWN subjects enrolled with small infarct cores had a broad range of baseline ASPECTS. Twenty-four-hour ASPECTS, strikingly influenced by endovascular therapy, predicted good clinical outcomes. REGISTRATION: https://www.clinicaltrials.gov; Unique identifier: NCT02142283.

Rapid Assessment of Acute Ischemic Stroke by Computed Tomography Using Deep Convolutional Neural Networks

Acute stroke is one of the leading causes of disability and death worldwide. Regarding clinical diagnoses, a rapid and accurate procedure is necessary for patients suffering from acute stroke. This study proposes an automatic identification scheme for acute ischemic stroke using deep convolutional neural networks (DCNNs) based on non-contrast computed tomographic (NCCT) images. Our image database for the classification model was composed of 1254 grayscale NCCT images from 96 patients (573 images) with acute ischemic stroke and 121 normal controls (681 images). According to the consensus of critical stroke findings by two neuroradiologists, a gold standard was established and used to train the proposed DCNN using machine-generated image features. Including the earliest DCNN, AlexNet, the popular Inception-v3, and ResNet-101 were proposed. To train the limited data size, transfer learning with ImageNet parameters was also used. The established models were evaluated by tenfold cross-validation and tested on an independent dataset containing 50 patients with acute ischemic stroke (108 images) and 58 normal controls (117 images) from another institution. AlexNet without pretrained parameters achieved an accuracy of 97.12%, a sensitivity of 98.11%, a specificity of 96.08%, and an area under the receiver operating characteristic curve (AUC) of 0.9927. Using transfer learning, transferred AlexNet, transferred Inception-v3, and transferred ResNet-101 achieved accuracies between 90.49 and 95.49%. Tested with a dataset from another institution, AlexNet showed an accuracy of 60.89%, a sensitivity of 18.52%, and a specificity of 100%. Transferred AlexNet, Inception-v3, and ResNet-101 achieved accuracies of 81.77%, 85.78%, and 80.89%, respectively. The proposed DCNN architecture as a computer-aided diagnosis system showed that training from scratch can generate a customized model for a specific scanner, and transfer learning can generate a more generalized model to provide diagnostic suggestions of acute ischemic stroke to radiologists.

CT perfusion based ASPECTS improves the diagnostic performance of early ischemic changes in large vessel occlusion

Background

ASPECTS scoring method varies, but which one is most suitable for predicting the prognosis still unclear. We aimed to evaluate the diagnostic performance of Automated (Auto)-, noncontrast CT (NCCT)- and CT perfusion (CTP) -ASPECTS for early ischemic changes (EICs) in acute ischemic stroke patients with large vessel occlusion (LVO) and to explore which scoring method is most suitable for predicting the clinical outcome.

Methods

Eighty-one patients with anterior circulation LVO were retrospectively enrolled and grouped as having a good (0–2) or poor (3–6) clinical outcome using a 90-day modified Rankin Scale score. Clinical characteristics and perfusion parameters were compared between the patients with good and poor outcomes. Differences in scores obtained with the three scoring methods were assessed. Diagnosis performance and receiver operating characteristic (ROC) curves were used to evaluate the value of the three ordinal or dichotomized ASPECTS methods for predicting the clinical outcome.

Results

Sixty-three patients were finally included, with 36 (57.1%) patients having good clinical outcome. Significant differences were observed in the ordinal or dichotomized Auto-, NCCT- and CTP-ASPECTS between the patients with good and poor clinical outcomes (all p < 0.01). The areas under the curves (AUCs) of the ordinal and dichotomized CTP-ASPECTS were higher than that of the other two methods (all p < 0.01), but the AUCs of the Auto-ASPECTS was similar to that of the NCCT-ASPECTS (p > 0.05).

Conclusions

The CTP-ASPECTS is superior to the Auto- and NCCT-ASPECTS in detecting EICs in LVO. CTP-ASPECTS with a cutoff value of 6 is a good predictor of the clinical outcome at 90-day follow-up.

Non-contrast dual-energy CT virtual ischemia maps accurately estimate ischemic core size in large-vessel occlusive stroke

Dual-energy CT (DECT) material decomposition techniques may better detect edema within cerebral infarcts than conventional non-contrast CT (NCCT). This study compared if Virtual Ischemia Maps (VIM) derived from non-contrast DECT of patients with acute ischemic stroke due to large-vessel occlusion (AIS-LVO) are superior to NCCT for ischemic core estimation, compared against reference-standard DWI-MRI. Only patients whose baseline ischemic core was most likely to remain stable on follow-up MRI were included, defined as those with excellent post-thrombectomy revascularization or no perfusion mismatch. Twenty-four consecutive AIS-LVO patients with baseline non-contrast DECT, CT perfusion (CTP), and DWI-MRI were analyzed. The primary outcome measure was agreement between volumetric manually segmented VIM, NCCT, and automatically segmented CTP estimates of the ischemic core relative to manually segmented DWI volumes. Volume agreement was assessed using Bland–Altman plots and comparison of CT to DWI volume ratios. DWI volumes were better approximated by VIM than NCCT (VIM/DWI ratio 0.68 ± 0.35 vs. NCCT/DWI ratio 0.34 ± 0.35; P < 0.001) or CTP (CTP/DWI ratio 0.45 ± 0.67; P < 0.001), and VIM best correlated with DWI (r_VIM = 0.90; r_NCCT = 0.75; r_CTP = 0.77; P < 0.001). Bland–Altman analyses indicated significantly greater agreement between DWI and VIM than NCCT core volumes (mean bias 0.60 [95%AI 0.39–0.82] vs. 0.20 [95%AI 0.11–0.30]). We conclude that DECT VIM estimates the ischemic core in AIS-LVO patients more accurately than NCCT.

Brain Imaging Findings and Response to Intravenous Thrombolysis in Posterior Circulation Stroke

INTRODUCTION

Intravenous thrombolysis (IVT) is a standard treatment for both anterior circulation ischaemic stroke (ACIS) and posterior circulation ischaemic stroke (PCIS). Our aim was to evaluate the predictors for a good clinical outcome and intracerebral haemorrhage (ICH) in patients undergoing posterior circulation IVT based on the initially performed CT or MR imaging.

METHODS

The study cohort consisted of 1643 consecutive patients with acute ischaemic stroke (1440 ACIS, 203 PCIS cases) who underwent IVT. ICH was classified according to the European Cooperative Acute Stroke Study (ECASS) I protocol. Clinical outcome was assessed using the modified Rankin scale (mRS). Early ischaemic signs and pre-existing structural signs were assessed.

RESULTS

Good clinical outcomes (mRS 0-1) were noted in 45.3% of patients with PCIS, with a mortality rate of 14.8%. ICH was noted in 8.3%, and a large haemorrhage was found in 2.4% of patients. Some early ischaemic signs and pre-existing structural signs on initial CT/MR imaging correlated significantly with the 90-day clinical outcome.

CONCLUSIONS

Early ischaemic signs and pre-existing structural signs should be considered during the assessment of patients with PCIS eligible for IVT. Tissue hypoattenuation on initial CT scans correlates with an increased risk of death. Similarly to anterior circulation, atrophy on initial MRI may negatively predict good clinical outcome in posterior circulation.

Brain Computed Tomography Angiography Maximum Intensity Projection Images for ASPECTS Derivation and Detection of Large Infarct Volumes: Preliminary Study

PURPOSE

Non-contrast CT ASPECTS (NCCT_asp) has an established role in determining eligibility for mechanical thrombectomy in centers without ready access to perfusion or DWI. Moreover, it has been suggested that CTA source ASPECTS (CTA_asp) may be superior to NCCT_asp in predicting final infarct volume (FIV). In this study, we hypothesized that CTA maximum intensity projection ASPECTS (MIPS_asp) would be superior compared to both NCCT_asp and CTA_asp in predicting FIV as measured by DWI.

MATERIALS AND METHODS

In 41 consecutive patients with MCA territory infarcts, NCCT_asp, CTA_asp and MIPS_asp were visually assessed by 2 neuroradiologists. Disagreements were adjudicated by a third neuroradiologist, and the reconciled data used for all further analysis. MR-DWI was used as the standard for FIV determination. Receiver operating characteristic curve analysis was used to compare the area under the curve for all three CT-based methods in predicting FIV ≥70 ml.

RESULTS

MIPS_asp (AUC: 0.98, CI: 0.88-1.00) were statistically better than NCCT_asp (AUC: 0.87, 95% CI: 0.72-0.95; p=0.01) in predicting FIV ≥70 ml. MIPS_asp were also superior to CTA_asp (AUC: 0.9, CI: 0.79-.98; p˂0.05). Optimal test performance for predicting FIV ≥70 ml for MIPS_asp was ≤6 (sensitivity=100%, specificity=91.4%; Youden's J=0.98).

CONCLUSION

Our preliminary study suggests that a novel CTA-MIPS derived ASPECTS better predicts large MCA territory infarcts compared to CTA source and non-contrast ASPECTS. Thus, MIPS_asp may be a promising technique for future studies aimed at improving ischemic stroke treatment in centers using ASPECTS for stroke management.

Motor evoked potentials during revascularization in ischemic stroke predict motor pathway ischemia and clinical outcome

OBJECTIVE

The relevance of motor evoked potential (MEP) recovery during mechanical endovascular thrombectomy (MT) in patients with ischemic stroke is unclear. We correlated MEP recovery during MT to symptom improvement and to ischemia in eloquent motor areas on magnetic resonance imaging (MRI) and compared the predictive value of MEPs to visual angiographic reperfusion status, classified by modified Thrombolysis in Cerebral Infarction grading (mTICI).

METHODS

Patients with hemisyndrome and large-vessel occlusion undergoing MT were included (n35, 49% females; 73.9 ± 14.5 years; n31 anterior circulation). MEPs were elicited transcranially and recorded at the abductor pollicis brevis muscle bilaterally throughout the procedure. An MRI was acquired within 7 days after MT.

RESULTS

The median door-to-needle time was 3.5 hours. Median National Institutes of Health Stroke Scale at presentation was 16 (7 - 37). Median Modified Rankin Scale score was 4 at day 7 and 3 months. After MT, MEP-recovery occurred in 21 cases after a median time span of 4.5 min [range 2 - 11 min]. Symptom improvement at day 7 (3 months) was noted in 22 (21) cases. Absence of ischemia on postinterventional MRI was noted in 21 cases, 19 of whom showed MEP-recovery. Stratified for symptom improvement at day 7, sensitivity (specificity) of MEP-recovery was 86% (85%) and of mTICI ≥ 2b was 95% (23%). Stratified for absence of ischemia on postinterventional MRI, sensitivity (specificity) of MEP-recovery was 90% (86%) and of mTICI ≥ 2b was of 95% (21%).

CONCLUSIONS

MEP recovery occurs early after successful endovascular mechanical revascularization and is superior to mTICI grading in predicting postoperative neurological outcome and postoperative motor-pathway ischemia.

SIGNIFICANCE

This is a new, significant and clinically important study since it emphasizes the additional value of MEP monitoring in a field, which has been traditionally unaffiliated with neurophysiological monitoring.

Tilt-Corrected Region Boundaries May Enhance the Alberta Stroke Program Early Computed Tomography Score for Less Experienced Raters

BACKGROUND

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is widely used to quantify early ischemic changes in the anterior circulation but has limited inter-rater reliability.

AIMS

We investigated whether application of 3-dimensional boundaries outlining the ASPECTS regions improves inter-rater reliability and accuracy.

METHODS

We included all patients from our DEFUSE 2 database who had a pretreatment noncontrast computed tomography scan (NCCT) of acceptable quality. Six raters (2 neuroradiologists, 2 vascular neurologists, and 2 neurology residents) scored ASPECTS of each NCCT without ("CT-native") and with the superimposed boundary template ("CT-template"). Gold-standard ASPECTS were generated by the 2 neuroradiologists through joint adjudication. Inter-rater reliability and accuracy were assessed using the intraclass correlation coefficient (ICC) for full-scale agreements and Gwet's AC1 for dichotomized (ASPECTS 0-6 vs 7-10) agreements.

RESULTS

Eighty-two patients were included. Inter-rater reliability improved with higher training level for both CT-native (ICC = .15, .31, .54 for residents, neurologists, and radiologists, respectively) and CT-template (ICC = .18, .33, .56). Use of the boundary template improved correlation with the gold-standard for one resident on full-scale agreement (ICC increased from .01 to .31, P = .01) and another resident on dichotomized agreement (AC1 increased from .36 to .64, P = .01), but resulted in no difference for other raters. The template did not improve ICC between raters of the same training level.

CONCLUSIONS

Inter-rater reliability of ASPECTS improves with physician training level. Standardized display of ASPECTS region boundaries on NCCT does not improve inter-rater reliability but may improve accuracy for some less experienced raters.

Scoring of Middle Cerebral Artery Collaterals Predicts RAPID CT-Perfusion Analysis and Short-Term Outcomes in Acute Ischemic Stroke Patients Undergoing Thrombectomy

OBJECTIVE

The rapid processing of perfusion and diffusion (RAPID) system for automating perfusion and diffusion data from head computed tomography has improved acute ischemic stroke treatment by quickly and accurately identifying those patients who may benefit from thrombectomy. Collateral scoring (CS) of cerebral arteries using computed tomography angiography (CTA) has proven useful in predicting postintervention infarct volumes and functional outcomes in ischemic stroke patients. Here we evaluate the relationship between CS and RAPID software in an effort to augment triage and provide improved predictability of functional outcomes in ischemic stroke patients.

METHODS

A retrospective review of 77 mechanical thrombectomy patients from January 2017 to October 2018 with large vessel occlusions of the anterior circulation who underwent RAPID and CTA imaging was performed. Baseline characteristics, RAPID data, CS, modified Rankin Scale score, and procedural data were collected. magnetic resonance imaging was used to calculate the postintervention stroke volume.

RESULTS

CS inversely correlates with the volume of RAPID cerebral blood flow <30% (β= -18.131, 95% confidence interval [CI] -24.384 to -11.879, P < 0.001), RAPID Tmax >6s (β= -22.205, 95% CI -39.125 to -5.285, P = 0.011), postintervention stroke volume (β= -30.637, 95% CI -41.554 to -19.720, P < 0.001), and discharge National Institutes of Health Stroke Scale score (β= -1.922, 95% CI -3.575 to -0.269, P = 0.023).

CONCLUSIONS

CS on CTA may be a useful way to identify patients who would benefit from mechanical thrombectomy and predict functional outcomes postintervention. CS may allow the stroke team to optimize the care of patients who may not be able to obtain RAPID analysis.

Acute symptomatic extracranial internal carotid occlusion - natural course and clinical impact

Background: To assess the vascular and clinical course of acute symptomatic extracranial internal carotid artery (ICA) occlusion. Patients and methods: Patients with an acute ischemic event in the anterior circulation and corresponding extracranial ICA occlusion at CT angiography and/or color-coded duplex sonography underwent recurrent duplex follow-up for detection of spontaneous recanalization. Stroke recurrence and functional outcome 4.5 months after the ischemic index event assessed by modified Rankin scale served as secondary outcome parameters. Results: 133 patients (91 men, mean age 62.3 years, SD 10.8) demonstrated symptomatic occlusion of the extracranial ICA with open intracranial ICA and open middle cerebral artery and were followed-up for spontaneous recanalization. Twenty-eight recanalized spontaneously, 25 to high-grade focal stenosis within 12 days, revealing an early cumulative recanalization rate of 23 %. Detection of recanalization was independently associated with de novo dual anti-platelet therapy (adjusted odds ratio [OR], 3.24; 95 % confidence interval [CI], 1.34 to 7.80). Ischemic recurrence occurred in 16 patients, of which 10 deemed to be embolic and 5 hemodynamic. Spontaneous ICA recanalization and an exhausted cerebrovascular reserve in the hemisphere distal to the occluded ICA were both independently associated with the occurrence of a recurrent ischemic event at Cox regression. An increasing NIHSS score at admission, a decreasing middle cerebral artery flow velocity and an ischemic recurrence independently predicted poor outcome (modified Rankin scale 3 to 6) in multivariate analysis. Conclusions: Acute symptomatic extracranial ICA occlusion is an unstable condition with frequent spontaneous recanalization to severe stenosis and early embolic stroke recurrence, demanding appropriate prevention especially in those patients with only mild deficit.