Region-specific interobserver agreement of the Alberta Stroke Program Early Computed Tomography Score: A meta-analysis

BACKGROUND AND PURPOSE

The Alberta Stroke Program Early CT Score (ASPECTS) is a widely used scoring system for evaluating ischemic stroke to determine therapeutic strategy. However, there is variation in the interobserver agreement of ASPECTS. This systematic review and meta-analysis aimed to investigate the interobserver agreement of total and regional ASPECTS.

METHODS

A comprehensive search was conducted in the Web of Sciences, PubMed, and Scopus databases to identify relevant studies. Inclusion criteria were studies of noncontrast CT performed within 24 hours of ischemic stroke in the middle cerebral artery territory.

RESULTS

A total of 20 studies, with 3482 patients, reporting interobserver agreement of total and regional ASPECTS were included in the meta-analysis. The interobserver agreement for total ASPECTS in studies using Kappa coefficient (κ) analysis was substantial (κ = .67, 95% confidence interval [CI]: .57-.78). In studies using intraclass correlation coefficient (ICC) analysis, agreement was excellent (ICC = .84, 95% CI: .77-.90). Interobserver agreement was higher in studies in which the observer was unblinded to clinical scenario in both groups (κ = .74, 95% CI: .59-.89, and ICC = .82, 95% CI: .79-.85). Per-region analysis showed that the caudate nucleus had the highest agreement (κ = .68, 95% CI: .60-.76, and ICC = .84, 95% CI: .74-.93), while M2 and internal capsule in Kappa studies (κ = .45, 95% CI: .34-.55 and κ = .47, 95% CI: .28-.66), and M4 and internal capsule in ICC studies (ICC = .54, 95% CI: .43-.64 and ICC = .55, 95% CI: .18-.91) had the lowest agreement.

CONCLUSION

This meta-analysis demonstrates substantial to excellent interobserver agreement for total ASPECTS, which supports using this method for stroke treatment. However, findings emphasize the need to consider interobserver agreement in specific regions of ASPECTS for treatment decisions.

A novel fully automated method for measuring ASPECTS to improve stroke diagnosis: Comparison to traditional ASPECTS

BACKGROUND AND PURPOSE

To compare the accuracy of subjective Alberta Stroke Program Early CT Score (sASPECTS) evaluation and that of an automated prototype software (aASPECTS) on nonenhanced CT (NECT) in patients with early anterior territory stroke and controls using side-to-side quantification of hypoattenuated brain areas.

METHODS

We retrospectively analyzed the NECT scans of 42 consecutive patients with ischemic stroke before reperfusion and 42 controls using first sASPECTS and subsequently aASPECTS. We assessed the differences in Alberta Stroke Program Early CT Score (ASPECTS) and calculated the sensitivity and specificity of NECT with CT perfusion, whereas cerebral blood volume (CBV) served as the reference standard for brain infarction.

RESULTS

The clot was located in the middle cerebral artery (MCA) in 47.6% of cases and the internal carotid artery (ICA) in 28.6% of cases. Ten cases presented combined ICA and MCA occlusions. The stroke was right sided in 52.4% of cases and left sided in 47.6%. Reader-based NECT analysis yielded a median sASPECTS of 10. The median CBV-based ASPECTS was 7. Compared to the area of decreased CBV, sASPECTS yielded a sensitivity of 12.5% and specificity of 86.8%. The software prototype (aASPECTS) yielded an overall sensitivity of 65.5% and a specificity of 92.2%. The interreader agreement for ASPECTS evaluation of admission NECT and follow-up CT was almost perfect (κ = .93). The interreader agreement of the CBV color map evaluation was substantial (κ = .77).

CONCLUSIONS

aASPECTS of NECT can outperform sASPECTS for stroke detection.

Correlation between clinical and brain computed tomography findings of stroke patients: A cross-sectional study

Background and Aims

In developing countries, the burden of stroke is growing and causing significant morbidity and disability with high mortality rates. Neuroimaging plays a crucial role in differentiating ischemic stroke from an intracerebral hemorrhage, as well as entities other than stroke. This study sought to determine the correlation between the clinical and brain CT scan findings of stroke patients attending three hospitals in Kampala, Uganda.

Methods

This was a cross-sectional study of clinically suspected stroke patients who were sent for brain CT scan at three selected hospitals in Kampala, Uganda. All brain CT scans of patients with suspected stroke were evaluated and the Alberta stroke program early CT score (ASPECTS) was used for middle cerebral artery (MCA) strokes. Univariate analysis was used to describe the clinico-demographic and brain CT features of stroke and summarized them as percentages. Bivariate and multivariate analysis were used to determine the adjusted odds ratios as a measure of association with a 95% confidence interval (CI).

Results

Of the 270 study participants, 141 (52.2%) were male. 162 (60%) had CT findings of stroke, and 90 (33.3%) had normal brain CT findings. Eighteen (6.7%) had other CT findings like tumor, dural hemorrhage, epidermoid cyst, and others. Ischemic stroke, hemorrhagic stroke, and subarachnoid hemorrhage accounted for 124 (45.9%), 34 (12.6%), and 4 (1.5%) respectively. Limb weakness (55.2%), headache (41.1%), and loss of consciousness (39.3%) were associated with stroke findings on CT. Among the acute ischemic strokes, 30 (73.2%) had a worse (0-7) ASPECT score. Those aged ≥65 years were associated with a worse ASPECTS [AOR: 22.01, (95% CI: 1.58-306.09) p = 0.021].

Conclusion

More than a third of patients with a clinical diagnosis of stroke had either no CT features of stroke or had other findings. The most commonly affected vascular territory was left MCA. Old age was strongly associated with having the worst ASPECTS score.

Automated estimation of ischemic core volume on noncontrast-enhanced CT via machine learning

BACKGROUND

Accurate estimation of ischemic core on baseline imaging has treatment implications in patients with acute ischemic stroke (AIS). Machine learning (ML) algorithms have shown promising results in estimating ischemic core using routine noncontrast computed tomography (NCCT).

OBJECTIVE

We used an ML-trained algorithm to quantify ischemic core volume on NCCT in a comparative analysis to pretreatment magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) in patients with AIS.

METHODS

Patients with AIS who had both pretreatment NCCT and MRI were enrolled. An automatic segmentation ML approach was applied using Brainomix software (Oxford, UK) to segment the ischemic voxels and calculate ischemic core volume on NCCT. Ischemic core volume was also calculated on baseline MRI DWI. Comparative analysis was performed using Bland-Altman plots and Pearson correlation.

RESULTS

A total of 72 patients were included. The time-to-stroke onset time was 134.2/89.5 minutes (mean/median). The time difference between NCCT and MRI was 64.8/44.5 minutes (mean/median). In patients who presented within 1 hour from stroke onset, the ischemic core volumes were significantly (p  =  0.005) underestimated by ML-NCCT. In patients presented beyond 1 hour, the ML-NCCT estimated ischemic core volumes approximated those obtained by MRI-DWI and with significant correlation (r  =  0.56, p < 0.001).

CONCLUSION

The ischemic core volumes calculated by the described ML approach on NCCT approximate those obtained by MRI in patients with AIS who present beyond 1 hour from stroke onset.

Association of Noncontrast Computed Tomography and Perfusion Modalities With Outcomes in Patients Undergoing Late-Window Stroke Thrombectomy

IMPORTANCE

There is substantial controversy with regards to the adequacy and use of noncontrast head computed tomography (NCCT) for late-window acute ischemic stroke in selecting candidates for mechanical thrombectomy.

OBJECTIVE

To assess clinical outcomes of patients with acute ischemic stroke presenting in the late window who underwent mechanical thrombectomy stratified by NCCT admission in comparison with selection by CT perfusion (CTP) and diffusion-weighted imaging (DWI).

DESIGN, SETTING, AND PARTICIPANTS

In this multicenter retrospective cohort study, prospectively maintained Stroke Thrombectomy and Aneurysm (STAR) database was used by selecting patients within the late window of acute ischemic stroke and emergent large vessel occlusion from 2013 to 2021. Patients were selected by NCCT, CTP, and DWI. Admission Alberta Stroke Program Early CT Score (ASPECTS) as well as confounding variables were adjusted. Follow-up duration was 90 days. Data were analyzed from November 2021 to March 2022.

EXPOSURES

Selection by NCCT, CTP, or DWI.

MAIN OUTCOMES AND MEASURES

Primary outcome was functional independence (modified Rankin scale 0-2) at 90 days.

RESULTS

Among 3356 patients, 733 underwent late-window mechanical thrombectomy. The median (IQR) age was 69 (58-80) years, 392 (53.5%) were female, and 449 (65.1%) were White. A total of 419 were selected with NCCT, 280 with CTP, and 34 with DWI. Mean (IQR) admission ASPECTS were comparable among groups (NCCT, 8 [7-9]; CTP, 8 [7-9]; DWI 8, [7-9]; P = .37). There was no difference in the 90-day rate of functional independence (aOR, 1.00; 95% CI, 0.59-1.71; P = .99) after adjusting for confounders. Symptomatic intracerebral hemorrhage (NCCT, 34 [8.6%]; CTP, 37 [13.5%]; DWI, 3 [9.1%]; P = .12) and mortality (NCCT, 78 [27.4%]; CTP, 38 [21.1%]; DWI, 7 [29.2%]; P = .29) were similar among groups.

CONCLUSIONS AND RELEVANCE

In this cohort study, comparable outcomes were observed in patients in the late window irrespective of neuroimaging selection criteria. Admission NCCT scan may triage emergent large vessel occlusion in the late window.

Total and regional ASPECT score for non-contrast CT, CT angiography, and CT perfusion: inter-rater agreement and its association with the final infarction in acute ischemic stroke patients

BACKGROUND

Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is a grading system to assess the extent and distribution of early ischemic changes.

PURPOSE

To assess inter-rater agreement for total and regional ASPECTS on non-contrast computed tomography (NCCT) images, CT angiography source images (CTA-SI), and CT-perfusion cerebral blood volume (CTP-CBV) maps, and their association with final infarction in patients with acute ischemic stroke (AIS).

MATERIAL AND METHODS

A total of 96 consecutive patients with AIS who underwent pre-treatment NCCT and CTP were retrospectively enrolled. CTA-SI was reconstructed using the raw data of CTP. Total and regional ASPECTS were assessed on baseline NCCT, CTA-SI, and CTP-CBV, and on follow-up NCCT or diffusion-weighted imaging. Follow-up ASPECTS served as the reference standard for final infarction.

RESULTS

CTP-CBV demonstrated higher concordance for total ASPECTS (interclass correlation coefficient, 0.895 vs. 0.771 vs. 0.777) and regional ASPECTS in internal capsule, lentiform, caudate nuclei, M5 and M6, compared with NCCT and CTA-SI. CTP-CBV showed a trend of stronger correlation with final ASPECTS than NCCT and CTA-SI (0.717 vs. 0.711 vs. 0.565; P > 0.05). ASPECTS in the internal capsule (ρ, 0.756 vs. 0.556; P = 0.016) and caudate nucleus (ρ, 0.717 vs. 0.476; P = 0.010) on CTP-CBV were more strongly correlated with follow-up ASPECTS than NCCT. CTP-CBV showed higher accuracy for predicting final infarction in the internal capsule (92.5% vs. 90.3% and 87.1%; P > 1.000, P = 0.125, respectively) and caudate nucleus (87.1% vs. 79.6% and 77.4%; P = 0.453, P = 0.039, respectively) than CTA-SI and NCCT.

CONCLUSION

CTP-CBV ASPECTS might be more reliable for delineating early ischemic changes and predicting final infarction.

Diagnostic accuracy of using Alberta Stroke Program Early Computed Tomography Score on CT perfusion map to predict a target mismatch in patients with acute ischemic stroke

PURPOSE

To assess the diagnostic accuracy of using Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on CT perfusion (CTP) map to predict a volumetric target mismatch in patients with acute ischemic stroke (AIS).

METHODS

Three-hundred and seven AIS patients with an onset time within 24h or unclear onset time who underwent CTP evaluation for large vessel occlusion of anterior circulation were enrolled. CTP ASPECTS was evaluated on cerebral blood flow (CBF) and time-to-maximum (Tmax) colored maps, respectively. Automated perfusion analysis software was used to calculate the volumes of ischemic core (volume_CBF<30%) and tissue at risk (volume_Tmax>6s). Target mismatch was defined as volume_{CBF< 30%}<70ml, volume_mismatch≥15ml, and volume_{Tmax >6s}/volume _{CBF< 30%}≥1.8. Spearman correlation and receiver operating characteristic curves were used for statistical analyses.

RESULTS

Strong correlations were found between CBF ASPECTS and volume_CBF<30%, and between Tmax ASPECTS and volume_Tmax>6s for overall population (ρ=-0.872, -0.757) and late-arriving patients (ρ=-0.900, -0.789). Mismatch ASPECTS moderately correlated with mismatch volume for overall population (ρ=0.498) and late-arriving patients (ρ=0.407). A CBF ASPECTS≥5 optimally predicted an ischemic core volume<70ml in overall population (sensitivity, 94.4%; specificity, 80.4%) and late-arriving patients (sensitivity, 89.5%; specificity, 90.5%). A CBF ASPECTS≥6 combined with a Mismatch ASPECTS≥1 optimally identified a target mismatch in overall population (sensitivity, 84.5%; specificity, 77.0%) and late-arriving patients (sensitivity, 83.7%; specificity, 90.0%).

CONCLUSION

CTP ASPECTS might be useful in predicting target mismatch derived from automated perfusion analysis software, and assisting in patient selection for endovascular therapy.

Prognostic value of ASPECTS on post-treatment diffusion-weighted imaging for acute ischemic stroke patients after endovascular thrombectomy: comparison with infarction volume

OBJECTIVES

To assess the prognostic value of Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on post-treatment diffusion-weighted imaging (DWI) for acute ischemic stroke (AIS) patients after endovascular thrombectomy (EVT) and compare it with that of infarction volume.

METHODS

Ninety-eight consecutive AIS patients who underwent EVT and post-treatment DWI were retrospectively enrolled. ASPECTS and infarction volume were evaluated based on post-treatment DWI, respectively. Good clinical outcome was defined as modified Rankin Scale score of 0-2 at 90 days. Predictors of good clinical outcome were evaluated using univariate and multivariate logistic regression analysis. Prognostic value of post-treatment DWI ASPECTS and infarction volume were assessed and compared using receiver-operating-characteristic curves and the DeLong method.

RESULTS

Favorable outcome was achieved in 62 (63.3%) patients. A strong correlation was found between post-treatment DWI ASPECTS and infarction volume (ρ = -0.847). Due to strong correlation and potential collinearity, two multivariate logistic regression models were respectively developed which included post-treatment DWI ASPECTS or infarction volume. As a result, post-treatment DWI ASPECTS (OR, 2.401; 95%CI, 1.567-3.678; p < 0.001) and infarction volume (OR, 0.982; 95%CI, 0.846-0.998; p = 0.002) were both independent predictors of good clinical outcome. Setting post-treatment DWI ASPECTS ≥ 6 as a cut-off value, optimal performance (AUC = 0.836; sensitivity, 87.1%; specificity, 66.7%) could be obtained in predicting good clinical outcome, which was comparable with that of infarction volume (cut-off volume, ≤ 94.87 ml; AUC = 0.821; sensitivity, 90.3%; specificity, 55.6%).

CONCLUSIONS

Post-treatment DWI ASPECTS might be a potential surrogate of infarction volume and be effective in predicting the clinical outcome of AIS patients after EVT.

KEY POINTS

• Post-treatment DWI ASPECTS correlated significantly with infarction volume. • A post-treatment DWI ASPECTS ≥ 6 best predicts good outcomes for AIS patients after EVT. • Post-treatment DWI ASPECTS has the potential in substituting infarction volume in predicting the clinical outcome of AIS patients.

Benefits of Endovascular Treatment in Late Window for Acute Ischemic Stroke Selected without CT Perfusion: A Real-World Study

Objective

This study examined the functional outcomes and safety of endovascular treatment (EVT) in acute ischemic stroke (AIS) patients owing to large vessel occlusion of the anterior circulation, presented during a late-time window (6–24 hours after last seen well (LSW)) in a real-world practice.

Methods

This was a retrospective analysis from a bi-center prospective cohort. According to the stroke treatment, patients with continuous Alberta Stroke Plan Early Aspect score (ASPECTS) ≥6 on non-contrast CT (NCCT) and moderate to good collateral state on CT angiography (CTA) were divided into EVT group and standard medical treatment (SMT) group. The primary outcome was the rate of functional independence (90-day mRS ≤2). Safety outcomes were the occurrence of symptomatic intracranial hemorrhage (sICH) and the 90-day mortality.

Results

Among the 288 enrolled patients (53.5% male, median age 64 years), there were 167 patients in the EVT group and 121 in the SMT group. After multivariable adjustments for potential confounders, EVT was associated with functional independence (adjusted OR: 3.052; 95% confidence interval (CI): 1.553–5.997; p = 0.001). In the PSM cohort, 44.2% (42/95) of patients in the EVT group versus 18.9% (18/95) in the SMT group achieved functional independence (OR: 3.39, 95% CI: 1.763–6.517), and there was a significant difference favoring EVT over the SMT in the overall distribution of mRS (OR: 2.170, 95% CI: 1.302–3.618) at 90 days. The rate of sICH did not differ between the EVT and SMT groups (10.5% vs 8.4%, p = 0.804) nor did 90-day mortality (18.9% vs 22.1%, p = 0.719). No interaction was found in p-values with statistical significance in subgroup analysis.

Conclusion

This real-world experience suggests that EVT for late-presenting stroke patients, based on small core on NCCT and moderate to good collaterals on CTA, is associated with better outcomes than SMT alone, with no increase in sICH and 90-day mortality rates.

Impact of Encephalomalacia and White Matter Hyperintensities on ASPECTS in Patients With Acute Ischemic Stroke: Comparison of Automated- and Radiologist-Derived Scores

Background: Automated software-based Alberta Stroke Program Early CT Score (ASPECTS) on unenhanced CT is associated with clinical outcomes after acute stroke. However, encephalomalacia or white matter hyperintensities (WMHs) may result in a falsely low automated ASPECTS if such findings are interpreted as early ischemia. Objective: To assess the impact of encephalomalacia and WMH on automated ASPECTS in patients with acute stroke, in comparison with radiologist-derived ASPECTS and clinical outcomes. Methods: This retrospective three-center study included 459 patients (322 men, 137 women; median age, 65 years) with acute ischemic stroke treated by IV thrombolysis who underwent baseline unenhanced CT within 6 hours after symptom onset and MRI within 24 hours after treatment. ASPECTS was determined by automated software and by three radiologists in consensus. Presence of encephalomalacia and extent of WMHs [categorized using the modified Scheltens scale (mSS)] were also determined using MRI. Kappa coefficients were used to compare ASPECTS between automated and radiologist-consensus methods. Multivariable logistic regression analyses and ROC analyses were performed to explore the predictive utility of baseline ASPECTS for unfavorable clinical outcome (90-day modified Rankin Scale score of 3-6) after thrombolysis. Results: Median automated ASPECTS was 9, and median radiologist-consensus ASPECTS was 10. Agreement between automated and radiologist-consensus ASPECTS, expressed as kappa, was 0.68, though was 0.76 in patients without encephalomalacia and 0.08 in patients with encephalomalacia. In patients without encephalomalacia, agreement decreased as the mSS score increased (e.g., 0.78 in subgroup with mSS score <10 vs 0.19 in subgroup with mSS >20). By anatomic region, agreement was highest for M5 (κ=0.52) and lowest for internal capsule (κ=0.18). In multivariable analyses, both automated (odds ratio=0.69) and radiologist-consensus (odds ratio=0.57) ASPECTS independently predicted unfavorable clinical outcome. For unfavorable outcome, automated ASPECTS had AUC of 0.70, sensitivity of 60.4%, and specificity of 71.0%, while radiologist-consensus ASPECTS had AUC of 0.72, sensitivity of 60.4%, and specificity of 80.5%. Conclusion: Presence of encephalomalacia or extensive WMH results in lower automated ASPECTS than radiologist-consensus ASPECTS, which may impact predictive utility of automated ASPECTS. Clinical Impact: When using automated ASPECTS, radiologists should manually confirm the score in patients with encephalomalacia or extensive leukoencephalopathy.

Novel selection paradigms for endovascular stroke treatment in the extended time window

BACKGROUND AND PURPOSE

The optimal selection methodology for stroke thrombectomy beyond 6 hours remains to be established.

METHODS

Review of a prospectively collected database of thrombectomy patients with anterior circulation strokes, adequate CT perfusion (CTP) maps, National Institute of Health Stroke Scale (NIHSS)≥10 and presenting beyond 6 hours from January 2014 to October 2018. Patients were categorised according to five selection paradigms: DAWN clinical-core mismatch (DAWN-CCM): between age-adjusted NIHSS and CTP core, DEFUSE 3 perfusion imaging mismatch (DEFUSE-3-PIM): between CTP-derived perfusion defect (Tmax >6 s lesion) and ischaemic core volumes and three non-contrast CT Alberta Stroke Program Early CT Score (ASPECTS)-based criteria: age-adjusted clinical-ASPECTS mismatch (aCAM): between age-adjusted NIHSS and ASPECTS, eloquence-adjusted clinical ASPECTS mismatch (eCAM): ASPECTS 6-10 and non-involvement of the right M6 and left M4 areas and standard clinical ASPECTS mismatch (sCAM): ASPECTS 6-10.

RESULTS

310 patients underwent analysis. DEFUSE-3-PIM had the highest proportion of qualifying patients followed by sCAM, eCAM, aCAM and DAWN-CCM (93.5%, 92.6%, 90.6%, 90% and 84.5%, respectively). Patients meeting aCAM, eCAM, sCAM and DAWN-CCM criteria had higher rates of 90-day good outcome compared with their non-qualifying counterparts(43.2% vs 12%,p=0.002; 42.4% vs 17.4%, p=0.02; 42.4% vs 11.2%, p=0.009; and 43.7% vs 20.5%, p=0.007, respectively). There was no difference between patients meeting DEFUSE-3-PIM criteria versus not(40.8% vs 31.3%,p=0.45). In multivariate analysis, all selection modalities except for DEFUSE-3-PIM were independently associated with 90-day good outcome.

CONCLUSIONS

ASPECTS-based selection paradigms for late presenting and wake-up strokes ET have comparable proportions of qualifying patients and similar 90-day functional outcomes as DAWN-CCM and DEFUSE-3-PIM. They also might lead to better outcome discrimination. These could represent a potential alternative for centres where access to advanced imaging is limited.

Accuracy and Prognostic Role of NCCT-ASPECTS Depend on Time from Acute Stroke Symptom-onset for both Human and Machine-learning Based Evaluation

Purpose

We hypothesize that the detectability of early ischemic changes on non-contrast computed tomography (NCCT) is limited in hyperacute stroke for both human and machine-learning based evaluation. In short onset-time-to-imaging (OTI), the CT angiography collateral status may identify fast stroke progressors better than early ischemic changes quantified by ASPECTS.

Methods

In this retrospective, monocenter study, CT angiography collaterals (Tan score) and ASPECTS on acute and follow-up NCCT were evaluated by two raters. Additionally, a machine-learning algorithm evaluated the ASPECTS scale on the NCCT (e-ASPECTS). In this study 136 patients from 03/2015 to 12/2019 with occlusion of the main segment of the middle cerebral artery, with a defined symptom-onset-time and successful mechanical thrombectomy (MT) (modified treatment in cerebral infarction score mTICI = 2c or 3) were evaluated.

Results

Agreement between acute and follow-up ASPECTS were found to depend on OTI for both human (Intraclass correlation coefficient, ICC = 0.43 for OTI < 100 min, ICC = 0.57 for OTI 100–200 min, ICC = 0.81 for OTI ≥ 200 min) and machine-learning based ASPECTS evaluation (ICC = 0.24 for OTI < 100 min, ICC = 0.61 for OTI 100–200 min, ICC = 0.63 for OTI ≥ 200 min). The same applied to the interrater reliability. Collaterals were predictors of a favorable clinical outcome especially in hyperacute stroke with OTI < 100 min (collaterals: OR = 5.67 CI = 2.38–17.8, p < 0.001; ASPECTS: OR = 1.44, CI = 0.91–2.65, p = 0.15) while ASPECTS was in prolonged OTI ≥ 200 min (collaterals OR = 4.21,CI = 1.36–21.9, p = 0.03; ASPECTS: OR = 2.85, CI = 1.46–7.46, p = 0.01).

Conclusion

The accuracy and reliability of NCCT-ASPECTS are time dependent for both human and machine-learning based evaluation, indicating reduced detectability of fast stroke progressors by NCCT. In hyperacute stroke, collateral status from CT-angiography may help for a better prognosis on clinical outcome and explain the occurrence of futile recanalization.

Supplementary Information

The online version of this article (10.1007/s00062-021-01110-5) contains supplementary material, which is available to authorized users.

Incremental value of Alberta Stroke Program Early CT Score to collateral score for predicting target mismatch in stroke patients with extended time window or unknown onset time

PURPOSE

To evaluate whether Alberta Stroke Program Early CT Score (ASPECTS) could provide incremental value to collateral score, and their integration could be an effective surrogate of CTP in predicting target mismatch.

MATERIAL AND METHODS

One hundred and fifty-nine stroke patients (onset time 6-16 h or with unknown onset time) with MCA and/or ICA occlusion underwent non-contrast computed tomography (NCCT) and CT perfusion (CTP) scan for initial assessment. Simulated single-phase CT angiography (sCTA, peak arterial phase) and multiphase CTA (mCTA) were reconstructed from CTP. ASPECTS was assessed on NCCT and sCTA. Collateral score was evaluated on mCTA. Target mismatch was defined as infarct core volume < 70 mL, the mismatch ratio ≥ 1.8, and the absolute mismatch volume ≥ 15 mL. Pearson correlation analysis, Mann-Whitney U test, chi-square test, and receiver operating characteristic curve analyses were performed.

RESULTS

Median CTA source image (CTA-SI) ASPECTS was significantly lower than NCCT ASPECTS (p = 0.001). NCCT ASPECTS, CTA-SI ASPECTS, and mCTA collateral score correlated significantly with infarct core volume and mismatch ratio (all p < 0.05). Mismatch group showed significantly higher NCCT ASPECTS, CTA-SI ASPECTS, and mCTA collateral score than non-mismatch group (all p < 0.001). NCCT ASPECTS and CTA-SI ASPECTS showed comparable predicting performance with mCTA collateral score (p > 0.05). Adding CTA-SI ASPECTS to mCTA collateral score improved the performance of mCTA in predicting target mismatch (area under curve, 0.905 vs. 0.804, p = 0.003).

CONCLUSION

ASPECTS can provide incremental information to collateral score in predicting target mismatch. If CTP scan fails, clinical decision based on ASPECTS and collateral score might be reasonable.

Assistance from Automated ASPECTS Software Improves Reader Performance

PURPOSE

To compare physicians' ability to read Alberta Stroke Program Early CT Score (ASPECTS) in patients with a large vessel occlusion within 6 hours of symptom onset when assisted by a machine learning-based automatic software tool, compared with their unassisted score.

MATERIALS AND METHODS

50 baseline CT scans selected from two prior studies (CRISP and GAMES-RP) were read by 3 experienced neuroradiologists who were provided access to a follow-up MRI. The average ASPECT score of these reads was used as the reference standard. Two additional neuroradiologists and 6 non-neuroradiologist readers then read the scans both with and without assistance from the software reader-augmentation program and reader improvement was determined. The primary hypothesis was that the agreement between typical readers and the consensus of 3 expert neuroradiologists would be improved with software augmented vs. unassisted reads. Agreement was based on the percentage of the individual ASPECT regions (50 cases, 10 regions each; N=500) where agreement was achieved.

RESULTS

Typical non-neuroradiologist readers agreed with the expert consensus read in 72% of the 500 ASPECTS regions, evaluated without software assistance. The automated software alone agreed in 77%. When the typical readers read the scan in conjunction with the software, agreement improved to 78% (P<0.0001, test of proportions). The software program alone achieved correlations for total ASPECT scores that were similar to the expert readers who had access to the follow-up MRI scan to help enhance the quality of their reads.

CONCLUSION

Typical readers had statistically significant improvement in their scoring of scans when the scan was read in conjunction with the automated software, achieving agreement rates that were comparable to neuroradiologists.

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.

Dynamic CTA-Derived Perfusion Maps Predict Final Infarct Volume: The Simple Perfusion Reconstruction Algorithm

BACKGROUND AND PURPOSE

Infarct core volume measurement using CTP (CT perfusion) is a mainstay paradigm for stroke treatment decision-making. Yet, there are several downfalls with cine CTP technology that can be overcome by adopting the simple perfusion reconstruction algorithm (SPIRAL) derived from multiphase CTA. We compare SPIRAL with CTP parameters for the prediction of 24-hour infarction.

MATERIALS AND METHODS

Seventy-two patients had admission NCCT, multiphase CTA, CTP, and 24-hour DWI. All patients had successful/quality reperfusion. Patient-level and cohort-level receiver operator characteristic curves were generated to determine accuracy. A 10-fold cross-validation was performed on the cohort-level data. Infarct core volume was compared for SPIRAL, CTP-time-to-maximum, and final DWI by Bland-Altman analysis.

RESULTS

When we compared the accuracy in patients with early and late reperfusion for cortical GM and WM, there was no significant difference at the patient level (0.83 versus 0.84, respectively), cohort level (0.82 versus 0.81, respectively), or the cross-validation (0.77 versus 0.74, respectively). In the patient-level receiver operating characteristic analysis, the SPIRAL map had a slightly higher, though nonsignificant (P < .05), average receiver operating characteristic area under the curve (cortical GM/WM, r = 0.82; basal ganglia  = 0.79, respectively) than both the CTP-time-to-maximum (cortical GM/WM = 0.82; basal ganglia = 0.78, respectively) and CTP-CBF (cortical GM/WM = 0.74; basal ganglia = 0.78, respectively) parameter maps. The same relationship was observed at the cohort level. The Bland-Altman plot limits of agreement for SPIRAL and time-to-maximum infarct volume were similar compared with 24-hour DWI.

CONCLUSIONS

We have shown that perfusion maps generated from a temporally sampled helical CTA are an accurate surrogate for infarct core.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

DWI-Based Algorithm to Predict Disability in Patients Treated with Thrombectomy for Acute Stroke

BACKGROUND AND PURPOSE

The reasons for poor clinical outcome after thrombectomy for acute stroke, concerning around half of all patients, are misunderstood. We developed a hierarchic algorithm based on DWI to better identify patients at high risk of disability.

MATERIALS AND METHODS

Our single-center, retrospective study included consecutive patients with acute ischemic stroke who underwent thrombectomy for large anterior artery occlusion and underwent pretreatment DWI. The primary outcome was the mRS at 3 months after stroke onset. Multivariable regression was used to identify independent clinical and imaging predictors of poor prognosis (mRS > 2) at 3 months, and a hierarchic algorithm predictive of disability was developed.

RESULTS

A total of 149 patients were analyzed. In decreasing importance, DWI lesion volume of >80 mL, baseline NIHSS score of >14, age older than 75 years, and time from stroke onset to groin puncture of >4 hours were independent predictors of poor prognosis. The predictive hierarchic algorithm developed from the multivariate analysis predicted the risk of disability at 3 months for up to 100% of patients with a high predictive value. The area under the receiver operating characteristic curve was 0.87.

CONCLUSIONS

The DWI-based hierarchic algorithm we developed is highly predictive of disability at 3 months after thrombectomy and is easy to use in routine practice.

Non-Contrast CT and CT-Angiogram for Late Window Ischemic Stroke Treatment Selection

INTRODUCTION

The benefit of late window endovascular treatment (EVT) for anterior circulation ischemic stroke has been demonstrated using perfusion-based neuroimaging. We evaluated whether non-contrast CT (NCCT) and CT-angiogram (CTA) alone can select late-presenting patients for EVT.

METHODS

We performed a retrospective comparison of all patients undergoing EVT at a single comprehensive stroke center from January 2016 to April 2017. Patients planned for EVT were divided into early (<6 hours from onset) and late (≥6 hours from onset or last time seen normal) window groups. Incidence of symptomatic hemorrhagic transformations (sHTs) at 24 hours and 3-month modified Rankin scores (mRSs) were compared.

RESULTS

During the study period, 204 (82%) patients underwent EVT in the early and 44 (18%) in the late window. Median (interquartile range) NIH Stroke Scale Score was similar between groups (early: 18 [15-23] vs. late: 17 [13-21]), as were median ASPECT scores (early: 9 [8-10] vs. late: 9 [7-9]). In the late window, 42 (95%) strokes were of unknown onset. Similar proportions of sHT occurred at 24 hours (early: 12 [6%] vs. late: 4 [9%], p = 0.43). At 3 months, the proportion of patients achieving functional independence (mRS 0-2) were comparable in the early (80/192 [42%]) and late (16/41 [39%]) windows (p = 0.76).

CONCLUSION

NCCT- and CTA-based patient selection led to similar functional independence outcomes and low proportions of sHT in the early and late windows. In centers without access to perfusion-based neuroimaging, this pragmatic approach could be safe, particularly for strokes of unknown onset.

Observer Agreement on Computed Tomography Perfusion Imaging in Acute Ischemic Stroke

Supplemental Digital Content is available in the text.

Computed tomography (CT) perfusion (CTP) provides potentially valuable information to guide treatment decisions in acute stroke. Assessment of interobserver reliability of CTP has, however, been limited to small, mostly single center studies. We performed a large, internet-based study to assess observer reliability of CTP interpretation in acute stroke.

Automated ASPECTS in Acute Ischemic Stroke: A Comparative Analysis with CT Perfusion

BACKGROUND AND PURPOSE

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 software against the assessment of a neuroradiologist in a comparative analysis with concurrent CTP-based CBV ASPECTS.

MATERIALS AND METHODS

Patients with anterior circulation stroke who had baseline NCCT and CTP and underwent successful mechanical thrombectomy were included. NCCT-ASPECTS was assessed by 2 neuroradiologists, and discrepancies were resolved by consensus. CTP-CBV ASPECTS was assessed by a different neuroradiologist. Automated ASPECTS was provided by Brainomix software. ASPECTS was dichotomized (ASPECTS ≥6 or <6) and was also based on the time from onset (>6 or ≤6 hours).

RESULTS

A total of 58 patients were included. The interobserver agreement for NCCT ASPECTS was moderate (κ = 0.48) and marginally improved (κ = 0.64) for dichotomized data. Automated ASPECTS showed excellent agreement with consensus reads (κ = 0.84) and CTP-CBV ASPECTS (κ = 0.84). Intraclass correlation coefficients for ASPECTS across all 3 groups were 0.84 (95% CI, 0.76-0.90, raw scores) and 0.94 (95% CI, 0.91-0.96, dichotomized scores). Automated scores were comparable with consensus reads and CTP-CBV ASPECTS in patients when grouped on the basis of time from symptom onset (>6 or ≤6 hours). There was significant (P < .001) negative correlation with final infarction volume and the 3 ASPECTS groups (r = -0.52, consensus reads; -0.58, CTP-CBV; and -0.66, automated).

CONCLUSIONS

ASPECTS derived from an automated software performs equally as well as consensus reads of expert neuroradiologists and concurrent CTP-CBV ASPECTS and can be used to standardize ASPECTS reporting and minimize interpretation variability.

Noncontrast CT versus Perfusion-Based Core Estimation in Large Vessel Occlusion: The Blood Pressure after Endovascular Stroke Therapy Study

BACKGROUND AND PURPOSE

The 2018 AHA guidelines recommend perfusion imaging to select patients with acute large vessel occlusion (LVO) for thrombectomy in the extended window. However, the relationship between noncontrast CT and CT perfusion imaging has not been sufficiently characterized >6 hours after last known normal (LKN).

METHODS

From a multicenter prospective cohort of consecutive adults who underwent thrombectomy for anterior LVO 0-24 hours after LKN, we correlated baseline core volume (rCBF < 30%) and the Alberta Stroke Program Early CT Scale (ASPECTS) score. We compared perfusion findings between patients with an unfavorable ASPECTS (<6) against those with a favorable ASPECTS (≥6), and assessed findings over time.

RESULTS

Of 485 enrolled patients, 177 met inclusion criteria (median age: 69 years, interquartile range [IQR: 57-81], 49% female, median ASPECTS 8 [IQR: 6-9], median core 10 cc [IQR: 0-30]). ASPECTS and core volume moderately correlated (r = -.37). A 0 cc core was observed in 54 (31%) patients, 70% of whom had ASPECTS <10. Of the 28 patients with ASPECTS <6, 3 (11%) had a 0 cc core. After adjustment for age and stroke severity, there was a lower ASPECTS for every 1 hour delay from LKN (cOR: 0.95, 95% confidence of interval [CI]: 0.91-1.00, P = .04). There was no difference in core (P = .51) or penumbra volumes (P = .87) across patients over time.

CONCLUSIONS

In this multicenter prospective cohort of patients who underwent thrombectomy, one-third of patients had normal CTP core volumes despite nearly three quarters of patients showing ischemic changes on CT. This finding emphasizes the need to carefully assess both noncontrast and perfusion imaging when considering thrombectomy eligibility.

Assessment of Cerebral Vasodilatory Capacity as Part of Catheter-Based Cerebral Angiography

BACKGROUND AND PURPOSE

Cerebral vasodilatory capacity assessment for risk stratification in patients with extracranial arterial stenosis or occlusion may be useful. We describe a new method that assesses cerebral vasodilatory capacity as part of catheter-based cerebral angiography.

METHODS

We prospectively assessed regional cerebral blood volume (rCBV) in the arterial distribution of interest using a controlled contrast injection in the common carotid or the subclavian arteries. rCBV maps were created using a predefined algorithm based on contrast distribution in the venous phase (voxel size: .466 mm³ ). rCBV maps were acquired again after selective administration of intra-arterial nicardipine (2.0 mg) distal to the stenosis. Two independent observers graded the change in rCBV in 10 predefined anatomical regions within the tributaries of the artery of interest (0 = reduction, 1 = no change, 2 = increase) and total rCBV change scores were summated.

RESULTS

Twenty-five patients with internal carotid artery stenosis (n = 18; 0-90% in severity) or extracranial vertebral artery stenosis (n = 7; 0-100% in severity) were assessed. There was an increase in rCBV in a tributary of the artery of interest in 18 of 25 after intra-arterial nicardipine (mean score: 11.98; range 0-19.5). There was no change or decrease in rCBV in 7 of 25 patients. The mean rCBV change score was similar in patients with an assessment of internal carotid artery or vertebral artery distributions (12.2 ± 5.3; 11.4 ± 2.5; P = .68).

CONCLUSION

Selective vasodilatory response to intra-arterial nicardipine in the affected arterial distribution during catheter-based cerebral angiography may provide new data for risk stratification.

Outcomes of Endovascular Thrombectomy vs Medical Management Alone in Patients With Large Ischemic Cores: A Secondary Analysis of the Optimizing Patient's Selection for Endovascular Treatment in Acute Ischemic Stroke (SELECT) Study

Importance

The efficacy and safety of endovascular thrombectomy (EVT) in patients with large ischemic cores remains unknown, to our knowledge.

Objective

To compare outcomes in patients with large ischemic cores treated with EVT and medical management vs medical management alone.

Design, Setting, and Participants

This prespecified analysis of the Optimizing Patient's Selection for Endovascular Treatment in Acute Ischemic Stroke (SELECT) trial, a prospective cohort study of imaging selection that was conducted in 9 US comprehensive stroke centers, enrolled patients between January 2016 and February 2018, and followed them up for 90 days. Patients with moderate to severe stroke and anterior circulation large-vessel occlusion presenting up to 24 hours from the time they were last known to be well were eligible for the cohort. Of these, patients with large ischemic cores on computed tomography (CT) (Alberta Stroke Program Early CT Score <6) or CT perfusion scanning (a volume with a relative cerebral blood flow <30% of ≥50 cm3) were included in analyses.

Exposures

Endovascular thrombectomy with medical management (MM) or MM only.

Main Outcomes and Measures

Functional outcomes at 90 days per modified Rankin scale; safety outcomes (mortality, symptomatic intracerebral hemorrhage, and neurological worsening).

Results

A total of 105 patients with large ischemic cores on either CT or CT perfusion images were included: 71 with Alberta Stroke Program Early CT Scores of 5 or less (EVT, 37; MM, 34), 74 with cores of 50 cm3 or greater on CT perfusion images (EVT, 39; MM, 35), and 40 who had large cores on both CT and CT perfusion images (EVT, 14; MM, 26). The median (interquartile range) age was 66 (60-75) years; 45 patients (43%) were female. Nineteen of 62 patients (31%) who were treated with EVT achieved functional independence (modified Rankin Scale scores, 0-2) vs 6 of 43 patients (14%) treated with MM only (odds ratio [OR], 3.27 [95% CI, 1.11-9.62]; P = .03). Also, EVT was associated with better functional outcomes (common OR, 2.12 [95% CI, 1.05-4.31]; P = .04), less infarct growth (44 vs 98 mL; P = .006), and smaller final infarct volume (97 vs 190 mL; P = .001) than MM. In the odds of functional independence, there was a 42% reduction per 10-cm3 increase in core volume (adjusted OR, 0.58 [95% CI, 0.39-0.87]; P = .007) and a 40% reduction per hour of treatment delay (adjusted OR, 0.60 [95% CI, 0.36-0.99]; P = .045). Of 10 patients who had EVT with core volumes greater than 100 cm3, none had a favorable outcome.

Conclusions and Relevance

Although the odds of good outcomes for patients with large cores who receive EVT markedly decline with increasing core size and time to treatment, these data suggest potential benefits. Randomized clinical trials are needed.

Image review on mobile devices for suspected stroke patients: Evaluation of the mRay software solution

PURPOSE

Software solutions such as mRay allow review of radiological images on handheld devices. We investigated if the quality is adequate for evaluating CT scans of patients with suspected stroke.

METHODS

50 patients (Median age 80 years, 28 females) were retrospectively selected. All patients had undergone multidetector CT angiography ± perfusion and presented with clinical signs of acute stroke. Out of the 50 patients, 19 had large-vessel occlusion (LVO), 5 had intracranial hemorrhage (ICH), 10 had severe intracranial stenosis of at least one major vessel, 2 had intracranial tumor and 15 had no or an unrelated pathology. One experienced neuroradiologist and one resident scored the anonymized pictures separately on two handheld devices (iPhone 7 Plus, MED-TAB) equipped with mRay Software and on a PACS workstation. Each case was reviewed on all three devices with a break in-between of at least 12 weeks. The scoring on the traditional workstation was compared with the two handheld devices, regarding detection of early ischemic signs, LVOs, CBV/CBF-mismatch, ICHs and severe stenosis. Both raters were asked to rate the diagnostic quality of both handheld devices regarding detection of LVOs, ICHs, early ischemic signs and overall.

RESULTS

All LVOs, intracranial tumors and ICHs were detected on both mobile devices. There was no significant difference in the rating of CCT and CBF ASPECTS between all three devices, while the sensitivity for detecting a CBF/CBV-mismatch was above 80% on both devices. Both raters assessed the diagnostic quality to be sufficient on both mobile devices to base treatment decisions on.

CONCLUSION

Software solutions such as mRay for handheld devices provide adequate diagnostic quality for the review of CT scans of suspected stroke patients.

Predicting cerebral edema in ischemic stroke patients

OBJECTIVES

To produce a scoring system for predicting the development of edema in ischemic stroke patients without edema on admission.

METHODS

This retrospective study included 572 ischemic stroke patients (73.3 ± 13.0 years, 300 male) without signs of cerebral edema on the first CT scan, which was performed on admission. Another scan was normally performed 3 days later, and subsequently whenever needed. Edema was defined as cerebral hypodensity with compression of lateral ventricles. The main clinical, laboratory, and instrumental variables obtained during the first 24 h were related to the appearance of edema on the CT scans performed after the first one.

RESULTS

Cerebral edema occurred in 158 patients (27.6%) after a median time of 4 days. The variables independently associated with edema development were (odds ratio, 95% CI) the following: (1) total anterior circulation syndrome (4.20, 2.55-6.93; P < 0.0001), (2) hyperdense appearance of middle cerebral artery (4.12, 2.03-8.36; P = 0.0001), (3) closed eyes (2.53, 1.39-4.60; P = 0.002), (4) vomiting (3.53, 1.45-8.60; P = 0.006), (5) lacunar cerebral syndrome (0.36, 0.17-0.77; P = 0.008); and (6) white matter lesions (0.53, 0.33-0.86; P = 0.01). Counting one positive point for the first four variables and one negative point for the last two variables, a scoring system (E-score) was built. Cerebral edema could be predicted when the score was ≥ 1 (positive predictive value 61.6%, specificity 85.3%, sensitivity 62.0%). The area under the receiver operating characteristic curve was 0.78.

CONCLUSIONS

In ischemic stroke patients, six variables obtained during the first 24 h of hospitalization were predictive of subsequent cerebral edema development.

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

Introduction

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

Objective

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

Methods

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

Results

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

Conclusions

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