Validity of acute stroke lesion volume estimation by diffusion-weighted imaging-Alberta Stroke Program Early Computed Tomographic Score depends on lesion location in 496 patients with middle cerebral artery stroke

MRI-based Quantitative Collateral Assessment in Acute Stroke : A Comparison with Single-phase CTA in Drip-and-ship Patients with Serial Imaging

PURPOSE

In acute ischemic stroke with large-vessel occlusion (LVO), collateral assessment with single-phase computed tomography angiography (CTA) might underestimate pial collateral supply in a considerable proportion of patients. We aimed to compare time-resolved magnetic resonance imaging (MRI)-based quantitative collateral mapping to conventional collateral imaging with CTA.

METHODS

This retrospective single-center study covering a period of 6 years (2012-2018) included drip-and-ship LVO patients who underwent MR imaging after initial imaging evaluation with CT. For MRI-based collateral assessment, T2*-weighted time series from perfusion-weighted imaging (PWI) were processed to compute a quantitative collateral vessel index (CVIPWI) based on the magnitude of signal variance across the entire acquisition time. CTA-based collateral scores (Tan and Maas) and CVIPWI were investigated in terms of inter-modality associations between collateral measures, as well as their relationships with stroke severity, infarct volume and early functional outcome.

RESULTS

The final analysis included n = 56 patients (n = 31 female, mean age 69.9 ± 14.21 years). No significant relationship was found between MR-based quantitative collateral supply (CVIPWI) and CT-based collateral scores (r = -0.00057, p = 0.502 and r = -0.124, p = 0.797). In contrast to CVIPWI, CTA-based collateral scores showed no significant relationship with clinical stroke severity and infarct volume. While MR-based CVIPWI was independently associated with favorable early functional outcome in multivariate analysis (OR 1.075, 95% CI 1.001-1.153, p = 0.046), CTA-based collateral scores were not significantly associated with outcome.

CONCLUSIONS

Since collateral scores based on single-phase CTA do not accurately reflect infarct progression and might underestimate pial collateralization in a relevant proportion of patients, they are not associated with early functional outcome in LVO patients. In contrast, CVIPWI represents a robust imaging parameter of collateral supply and is independently associated with functional outcome.

Comparison of HEmorrhage on CT versus MRI After ThrombEctomy: The HECATE study

Background

The characterization of hemorrhage following acute stroke intervention has largely been CT-based. We sought to compare MRI- and CT-based scoring of hemorrhage after acute endovascular therapy (EVT) applying the Heidelberg Bleeding Classification (HBC) to assess inter-modal agreement and quantify inter-rater agreement.

Methods

Consecutive acute stroke patients were included in this retrospective study if they: i) had MRI and CT ≤12 hours of each other OR ii) had CT bracketed by MRI pre- and post-CT [i.e. MRI-CT-MRI] ≤7 days post-EVT. The concordance of the HBC ratings by consensus panel were compared between CT and T2*GRE MRI.

Results

For the 87 EVT-treated patients included, median age was 68 years [60-74], admit NIHSS 18 [13-23], 47% were treated with IV/IA thrombolytics, and 93% were successfully recanalized (mTICI 2b/3). Hemorrhage was detected on at least one modality in 60% (52/87) of patients. We found a 68% (59/87, 95% CI [57-77%]) agreement overall between CT and MRI for hemorrhage classification post-EVT. MRI had the best inter-rater agreement for HBC 0 (no hemorrhage) with excellent concordance (κ=0.882), compared to CT (κ=0.683). T2*GRE MRI tended to have increased sensitivity to scattered petechial hemorrhage (HBC 1a) as compared to CT with 17% (2/12) inter-modal agreement. The inter-rater agreement of HBC class 2 (i.e. PH-2) was substantial for MRI (κ=0.781) and excellent in CT (κ=0.951), with 67% (8 /12) inter-modal agreement. SAH was detected in 24% (21/87) of patients on CT and/or MRI with 29% (6/21) inter-modal agreement.

Conclusions

With the exception of SAH and minor petechial hemorrhagic transformation, we found that MRI and CT are overall interchangeable for detecting and classifying hemorrhage after endovascular therapy, reassuring findings for both clinical-decision making and research application. Given the complexity of hemorrhage subtypes post-EVT, work to further refine a post-EVT hemorrhage classification scale with clinical correlation would be beneficial.

Clinical Significance of Diffusion-Weighted Brain MRI Lesions After TAVR: Results of a Patient-Level Pooled Analysis

BACKGROUND

Acute brain infarction detected by diffusion-weighted magnetic resonance imaging (DW-MRI) is common after transcatheter aortic valve replacement (TAVR), but its clinical relevance is uncertain.

OBJECTIVES

The authors investigated the relationship between DW-MRI total lesion number (TLN), individual lesion volume (ILV), and total lesion volume (TLV) and clinical stroke outcomes after TAVR.

METHODS

Patient-level data were pooled from 4 prospective TAVR embolic protection studies, with consistent predischarge DW-MRI acquisition and core laboratory analysis. C-statistic was used to determine the best DW-MRI measure associated with clinical stroke.

RESULTS

A total of 495 of 603 patients undergoing TAVR completed the predischarge DW-MRI. At 30 days, the rate of clinical ischemic stroke was 6.9%. Acute ischemic brain injury was seen in 85% of patients with 5.5 ± 7.3 discrete lesions per patient, mean ILV of 78.2 ± 257.1 mm3, and mean TLV of 555 ± 1,039 mm3. The C-statistic was 0.84 for TLV, 0.81 for number of lesions, and 0.82 for maximum ILV in predicting ischemic stroke. On the basis of the TLV cutpoint as defined by receiver operating characteristic (ROC), patients with a TLV >500 mm3 (vs TLV ≤500 mm3) had more ischemic stroke (18.2% vs 2.3%; P < 0.0001), more disabling strokes (8.8% vs 0.9%; P < 0.0001), and less complete stroke recovery (44% vs 62.5%; P = 0.001) at 30 days.

CONCLUSIONS

Our study confirms that the number, size, and total volume of acute brain infarction defined by DW-MRI are each associated with clinical ischemic strokes, disabling strokes, and worse stroke recovery in patients undergoing TAVR and may have value as surrogate outcomes in stroke prevention trials. (A Prospective, Randomized Evaluation of the TriGuard™ HDH Embolic Deflection Device During TAVI [DEFLECT III]; NCT02070731) (A Study to Evaluate the Neuro-embolic Consequences of TAVR [NeuroTAVR]; NCT02073864) (The REFLECT Trial: Cerebral Protection to Reduce Cerebral Embolic Lesions After Transcatheter Aortic Valve Implantation [REFLECT I]; NCT02536196) (The REFLECT Trial: Cerebral Protection to Reduce Cerebral Embolic Lesions After Transcatheter Aortic Valve Implantation [REFLECT II]; NCT02536196).

Clinical and imaging predictors for hemorrhagic transformation of acute ischemic stroke after endovascular thrombectomy

BACKGROUND AND PURPOSE

Hemorrhagic transformation (HT) is a common complication of endovascular thrombectomy (EVT) in patients with acute ischemic stroke (AIS). Our study aims to investigate the clinical and imaging predictors of HT and symptomatic intracranial hemorrhage (sICH) in patients who underwent EVT.

METHODS

A retrospective analysis of 118 patients undergoing EVT for acute anterior circulation stroke was performed. Potential clinical and imaging predictors of all patients were collected and multivariate logistic regression was performed. The risk prediction system was constructed according to the multivariate logistic regression results.

RESULTS

The incidence of HT and sICH after EVT were 46.6% and 15.3%, respectively. The multivariate logistic regression results showed that Alberta Stroke Program Early CT Score (ASPECTS) (p = .001, odds ratio [OR] = 0.367, 95% [confidence interval] CI, 0.201-0.670), collateral status (p<.001, OR = 0.117, 95% CI, 0.042-0.325), relative cerebral blood flow (CBF) ratio (p = .025, OR = 0.943, 95% CI, 0.895-0.993), and blood glucose on admission (p = .012, OR = 1.258, 95% CI, 1.053-1.504) were associated with HT. While for sICH, collateral circulation (p = .007, OR = 0.148, 95% CI, 0.037-0.589), ASPECTS (p = .033, OR = 0.510, 95% CI, 0.274-0.946), and blood glucose (p = .005, OR = 1.304, 95% CI, 1.082-1.573) were independent factors. The predictive model for HT after EVT was established, and the sensitivity and specificity of it were 90.9% and 79.4%, respectively, with the area under the curve of 90.0% (84.5%-95.4%).

CONCLUSION

Collateral status, ASPECTS, relative CBF ratio, and blood glucose on admission were predictors for HT in AIS patients, while collateral status, ASPECTS, and blood glucose on admission were also predictors for sICH. In addition, the established predictive model showed good diagnostic value for prediction of HT after EVT.

Early and late infarct growth rate in ischemic stroke patients after successful endovascular treatment in early time window: correlation of imaging and clinical factors with clinical outcome

Background

The prospective study assessed infarct growth rate (IGR) in acute ischemic stroke (AIS) with large vessel occlusion (LVO) after recanalization in early time window. Early IGR (EIGR) and late IGR (LIGR) were correlated with imaging and clinical data; we searched for outcome predictors.

Methods

We included 71 consecutive patients. Subjects underwent computed tomography perfusion (CTP) for ischemic core volume assessment at 99.0 minutes (median) from stroke onset, recanalization was performed at 78.0 minutes (median) from CTP. Final infarct volume (FIV) was measured on 24±2 hours imaging follow-up. EIGR was calculated as the core volume/time between stroke onset and CTP; LIGR was calculated as FIV/time between CTP and imaging follow-up. Twenty-two subjects were assessed as poor outcome, 49 as good outcome. Group differences were tested by Mann-Whitney test and χ2 test. Bayesian logistic regression models were used to predict clinical outcome, Pearson correlations for the log-transformed predictors.

Results

Subjects with poor outcome were older, median age 78.0 [interquartile range (IQR): 71.8, 83.8] versus 68.0 (IQR: 57.0, 73.0) years; 95% confidence interval (CI): 6.00 to 16.00; P<0.001. Their stroke severity scale was higher, median 19.0 (IQR: 16.0, 20.0) versus 15.5 (IQR: 10.8, 18.0); 95% CI: 1.00 to 6.00; P<0.001. They had higher EIGR, median 23.9 (IQR: 6.4, 104.0) versus 6.7 (IQR: 1.7, 13.0) mL/h; 95% CI: 3.26 to 53.68; P=0.002; and larger core, median 52.5 (IQR: 13.1, 148.5) versus 10.0 (IQR: 1.4, 20.0) mL; 95% CI: 11.00 to 81.00; P<0.001. In subjects with poor outcome, infarct growth continued after thrombectomy with LIGR 2.0 (IQR: 1.2, 9.7) versus 0.3 (IQR: 0.0, 0.7) mL/h; 95% CI: 1.10 to 6.10; P<0.001; resulting in larger FIV, median 186.5 (IQR: 49.3, 280.8) versus 18.5 (IQR: 8.0, 34.0) mL; 95% CI: 55.30 to 214.00; P<0.001. Strong correlations among predictors were found e.g., core and EIGR (r=0.942), LIGR and FIV (r=0.779), core and FIV (r=0.761). Clinical outcome was best predicted using data from later measurements as FIV and LIGR.

Conclusions

Data from later measurements were more predictive, there was no major benefit to use growth over volume data.

Neurological Functional Independence After Endovascular Thrombectomy and Different Imaging Modalities for Large Infarct Core Assessment : A Systematic Review and Meta-analysis

PURPOSE

To investigate the rate of neurological functional independence (NFI) at 90 days in patients with large infarct core (LIC), which was evaluated by different imaging modalities before endovascular thrombectomy (EVT).

METHODS

PubMed and EMBASE were searched for original studies on clinical functional outcomes at 90 days in LIC patients who received EVT treatment from inception to 28 September 2021. The pooled NFI rates were calculated using random effects model according to different imaging modalities and criteria.

RESULTS

We included 34 studies enrolling 2997 LIC patients. The NFI rates were 23% (95% confidence interval, CI 15-32%) and 24% (95% CI 10-38%) when LIC was defined as core volume ≥50 ml and ≥ 70 ml separately on computed tomography perfusion, 36% (95% CI 23-48%) and 21% (95% CI 17-25%) when LIC was defined as core volume ≥ 50 ml and ≥ 70 ml separately on magnetic resonance diffusion-weighted imaging (DWI), 28% (95% CI 24-32%) and 37% (95% CI 21-53%) when LIC was defined as DWI-ASPECTS ≤ 5 and ≤ 6 separately, 23% (95% CI 19-27%) and 32% (95% CI 18-46%) when LIC was defined as NCCT-ASPECTS ≤ 5 and ≤ 6 separately.

CONCLUSION

Similar NFI rates could be obtained after EVT in LIC patients if proper LIC criteria were select according to the imaging modality.

Neuroimaging of Acute Ischemic Stroke: Multimodal Imaging Approach for Acute Endovascular Therapy

Advances in acute ischemic stroke (AIS) treatment have been contingent on innovations in neuroimaging. Neuroimaging plays a pivotal role in the diagnosis and prognosis of ischemic stroke and large vessel occlusion, enabling triage decisions in the emergent care of the stroke patient. Current imaging protocols for acute stroke are dependent on the available resources and clinicians' preferences and experiences. In addition, differential application of neuroimaging in medical decision-making, and the rapidly growing evidence to support varying paradigms have outpaced guideline-based recommendations for selecting patients to receive intravenous or endovascular treatment. In this review, we aimed to discuss the various imaging modalities and approaches used in the diagnosis and treatment of AIS.

Internal border zone injury predicts the functional outcome of acute MCA stroke patients

BACKGROUND AND PURPOSE

Classification of deep (D), superficial (S) MCA territories and their junctional vascular area (the internal border zone, IBZ) can help to identify patients most likely to benefit from aggressive reperfusion therapy after stroke. We tested the prognostic value of an IBZ injury compared to DWI-ASPECTS and infarct volume.

MATERIALS AND METHODS

DW lesions of 168 patients with acute (4.2±6.5 h) MCA strokes were retrospectively examined and manually delineated. Patients with haemorrhagic transformation or other neurological diseases were excluded. Clinical data were recorded within 24 h following symptom onset and 48 h for patients who benefited from reperfusion therapy. The occurrence of an IBZ injury was determined using a standardized stereotaxic atlas. Performance to predict a good outcome (mRS<3 at 3 months) was estimated through ROC curves for DWI-ASPECTS≤6, lesion volume≥100 mL and IBZ injury. Logistic regression models were performed to estimate independent outcomes for infarct volume and IBZ injury.

RESULTS

Infarcts involving the IBZ were larger (94.9±98.8 mL vs. 30.2±31.3 mL), had higher NIHSS (13.8±7.2 vs. 7.2±5.7), more frequent MCA occlusions (64.9% vs. 28.3%), and worse outcomes (mRS 3.0±1.8 vs. 1.9±1.7), and were less responsive to IVtPA (34±47% vs. 55±48% of NIHSS improvement). The area under the ROC curves was comparable between the occurrence of IBZ injury (0.651), ASPECTS≤6 (0.657) and volume≥100 mL (0.629). Logistic regression analyses showed an independent effect of an IBZ injury, especially for superficial MCA strokes and for patients who benefited from reperfusion therapy.

CONCLUSION

An IBZ injury is an early and independent marker of stroke severity, functional prognosis and treatment responsiveness.

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.

Cerebral Edema in Patients With Large Hemispheric Infarct Undergoing Reperfusion Treatment: A HERMES Meta-Analysis

BACKGROUND AND PURPOSE

Whether reperfusion into infarcted tissue exacerbates cerebral edema has treatment implications in patients presenting with extensive irreversible injury. We investigated the effects of endovascular thrombectomy and reperfusion on cerebral edema in patients presenting with radiological evidence of large hemispheric infarction at baseline.

METHODS

In a systematic review and individual patient-level meta-analysis of 7 randomized controlled trials comparing thrombectomy versus medical therapy in anterior circulation ischemic stroke published between January 1, 2010, and May 31, 2017 (Highly Effective Reperfusion Using Multiple Endovascular Devices collaboration), we analyzed the association between thrombectomy and reperfusion with maximal midline shift (MLS) on follow-up imaging as a measure of the space-occupying effect of cerebral edema in patients with large hemispheric infarction on pretreatment imaging, defined as diffusion-magnetic resonance imaging or computed tomography (CT)-perfusion ischemic core 80 to 300 mL or noncontrast CT-Alberta Stroke Program Early CT Score ≤5. Risk of bias was assessed using the Cochrane tool.

RESULTS

Among 1764 patients, 177 presented with large hemispheric infarction. Thrombectomy and reperfusion were associated with functional improvement (thrombectomy common odds ratio =2.30 [95% CI, 1.32-4.00]; reperfusion common odds ratio =4.73 [95% CI, 1.66-13.52]) but not MLS (thrombectomy β=-0.27 [95% CI, -1.52 to 0.98]; reperfusion β=-0.78 [95% CI, -3.07 to 1.50]) when adjusting for age, National Institutes of Health Stroke Score, glucose, and time-to-follow-up imaging. In an exploratory analysis of patients presenting with core volume >130 mL or CT-Alberta Stroke Program Early CT Score ≤3 (n=76), thrombectomy was associated with greater MLS after adjusting for age and National Institutes of Health Stroke Score (β=2.76 [95% CI, 0.33-5.20]) but not functional improvement (odds ratio, 1.71 [95% CI, 0.24-12.08]).

CONCLUSIONS

In patients presenting with large hemispheric infarction, thrombectomy and reperfusion were not associated with MLS, except in the subgroup with very large core volume (>130 mL) in whom thrombectomy was associated with increased MLS due to space-occupying ischemic edema. Mitigating cerebral edema-mediated secondary injury in patients with very large infarcts may further improve outcomes after reperfusion therapies.

[Imaging-based patient selection for mechanical thrombectomy based on time since symptom onset]

BACKGROUND

In ischemic stroke due to large vessel occlusion (LVO), the indications for patient selection for endovascular mechanical thrombectomy (MT) are based on findings from brain imaging. Several imaging protocols from computed tomography (CT) or magnetic resonance imaging (MRI) are available to guide treatment decisions.

OBJECTIVE

To recommend the optimal choice of imaging modalities and protocols for MT with respect to time windows from symptom onset.

MATERIAL AND METHODS

Evaluation of the results of large randomized placebo-controlled trials regarding imaging-based patient selection in MT categorized by time intervals since symptom onset. We discuss methodological aspects, advantages and caveats of individual stroke imaging protocols. Summary of recommendations for the practice.

RESULTS AND CONCLUSION

In MT trials CT was mostly used for patient selection. Plain CT combined with CT angiography or additional perfusion imaging is the preferred option. In early time windows CT with CTA is adequate (≤ 6 h for MT, ≤ 4.5 h in cases of accompanying thrombolysis according to exclusion criteria). In later or unknown time windows perfusion imaging is needed for patient selection. Patients presenting with unknown time windows should be examined by MRI as a first-line choice in mild to moderate deficits, in cases of severe deficits CT imaging with perfusion imaging.

Higher Baseline Cortical Score Predicts Good Outcome in Patients With Low Alberta Stroke Program Early Computed Tomography Score Treated with Endovascular Treatment

BACKGROUND

Patients with large vessel occlusion and noncontrast computed tomography (CT) Alberta Stroke Program Early CT Score (ASPECTS) <6 may benefit from endovascular treatment (EVT). There is uncertainty about who will benefit from it.

OBJECTIVE

To explore the predicting factors for good outcome in patients with ASPECTS <6 treated with EVT.

METHODS

We retrospectively reviewed 60 patients with ASPECTS <6 treated with EVT in our center between March 2018 and June 2019. Patients were divided into 2 groups because of the modified Rankin Score (mRS) at 90 d: good outcome group (mRS 0-2) and poor outcome group (mRS ≥3). Baseline and procedural characteristics were collected for unilateral variate and multivariate regression analyses to explore the influent variates for good outcome.

RESULTS

Good outcome (mRS 0-2) was achieved in 24 (40%) patients after EVT and mortality was 20% for 90 d. Compared with the poor outcome group, higher baseline cortical ASPECTS (c-ASPECTS), lower intracranial hemorrhage, and malignant brain edema after thrombectomy were noted in the good outcome group (all P < .01). Multivariate logistic regression showed that only baseline c-ASPECTS (≥3) was positive factor for good outcome (odds ratio = 4.29; 95% CI, 1.21-15.20; P = .024). The receiver operating characteristics curve indicated a moderate value of c-ASPECTS for predicting good outcome, with the area under receiver operating characteristics curve 0.70 (95% CI, 0.56-0.83; P = .011).

CONCLUSION

Higher baseline c-ASPECTS was a predictor for good clinical outcome in patients with ASPECTS <6 treated with EVT, which could be helpful to treatment decision.

Predictive value of Alberta stroke program early CT score for perfusion weighted imaging - diffusion weighted imaging mismatch in stroke with middle cerebral artery occlusion

This study aimed to quantitatively assess the consistency and correlation between perfusion weighted imaging (PWI)/ diffusion weighted imaging (DWI) Alberta Stroke Program Early CT Score (ASPECTS) mismatch and PWI/DWI mismatch.Sixty-eight acute ischemic stroke with middle cerebral artery occlusion who underwent magnetic resonance imaging before thrombectomy were eligible. DWI volume, PWI volume and PWI-DWI mismatch were measured. DWI-, PWI-, PWI-DWI ASPECTS were evaluated. Statistical analysis was performed to compare the correlation between volume and ASPECTS of DWI-, PWI- and PWI-DWI mismatch. Receiver operating characteristic curve analysis was used to assess the predictive value of the PWI-DWI ASPECTS mismatch for the occurrence of PWI-DWI mismatch in acute ischemic stroke patients with middle cerebral artery occlusion.Of 68 patients, the DWI volume, PWI volume and PWI-DWI mismatch volume were (27.76 ± 17.53) mL, (167.09 ± 59.64) mL and (139.33 ± 58.18) mL respectively. DWI-ASPECTS was 6.75 ± 1.90 with the interobserver agreement was κ=0.98 (95% CI, 0.95-0.99); PWI-ASPECTS was 3.09 ± 2.11 with the interobserver agreement was κ=0.95 (95% CI, 0.91-0.99); PWI-DWI ASPECTS mismatch was 6.75 ± 1.90. Spearman's rank correlation analysis revealed that PWI-DWI mismatch volume was negatively correlated with PWI-DWI ASPECTS mismatch (r = -0.802; P = .000). Receiver operating characteristic analysis showed that when the PWI-DWI ASPECTS mismatch cut point was ≥ 2, the under curve of PWI-DWI ASPECTS mismatch for predicting PWI-DWI mismatch was 0.954 (95%CI, 0.911-0.998), with the sensitivity and specificity were 84.00% and 100% respectively.PWI-DWI ASPECTS mismatch may represent a convenient surrogate for penumbra in clinical trials.

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.

Silent Brain Infarcts Following Cardiac Procedures: A Systematic Review and Meta-Analysis

Background

Silent brain infarcts (SBI) are increasingly being recognized as an important complication of cardiac procedures as well as a potential surrogate marker for studies on brain injury. The extent of subclinical brain injury is poorly defined.

Methods and Results

We conducted a systematic review and meta‐analysis utilizing studies of SBIs and focal neurologic deficits following cardiac procedures. Our final analysis included 42 studies with 49 separate intervention groups for a total of 2632 patients. The prevalence of SBIs following transcatheter aortic valve implantation was 0.71 (95% CI 0.64‐0.77); following aortic valve replacement 0.44 (95% CI 0.31‐0.57); in a mixed cardiothoracic surgery group 0.39 (95% CI 0.28‐0.49); coronary artery bypass graft 0.25 (95% CI 0.15‐0.35); percutaneous coronary intervention 0.14 (95% CI 0.10‐0.19); and off‐pump coronary artery bypass 0.14 (0.00‐0.58). The risk ratio of focal neurologic deficits to SBI in aortic valve replacement was 0.22 (95% CI 0.15‐0.32); in off‐pump coronary artery bypass 0.21 (95% CI 0.02‐2.04); with mixed cardiothoracic surgery 0.15 (95% CI 0.07‐0.33); coronary artery bypass graft 0.10 (95% CI 0.05‐0.18); transcatheter aortic valve implantation 0.10 (95% CI 0.07‐0.14); and percutaneous coronary intervention 0.06 (95% CI 0.03‐0.14). The mean number of SBIs per patient was significantly higher in the transcatheter aortic valve implantation group (4.58 ± 2.09) compared with both the aortic valve replacement group (2.16 ± 1.62, P=0.03) and the percutaneous coronary intervention group (1.88 ± 1.02, P=0.03).

Conclusions

SBIs are a very common complication following cardiac procedures, particularly those involving the aortic valve. The high frequency of SBIs compared with strokes highlights the importance of recording this surrogate measure in cardiac interventional studies. We suggest that further work is required to standardize reporting in order to facilitate the use of SBIs as a routine outcome measure.

Early successful reperfusion after endovascular therapy reduces malignant middle cerebral artery infarction occurrence in young patients with large diffusion-weighted imaging lesions

BACKGROUND AND PURPOSE

Malignant middle cerebral artery infarction (MMI) is a severe complication of acute ischaemic stroke (AIS). The aim of our study was to assess whether successful reperfusion after endovascular therapy (EVT) in AIS with clinical and imaging predictors of MMI decreased its occurrence.

METHODS

Data were collected between January 2014 and July 2018 in a monocentric prospective AIS registry of patients treated with EVT. Patients selected were <65 years old with severe anterior circulation AIS with a National Institutes of Health Stroke Scale score >15, baseline Diffusion-Weighted Imaging-Alberta Stroke Program Early Computed Tomography Score ≤ 6 and baseline diffusion-weighted imaging lesion volume >82 mL within 6 h of symptom onset. Successful reperfusion was defined as a Thrombolysis in Cerebral Ischemia score ≥ 2b. Occurrence of MMI was the primary endpoint.

RESULTS

A total of 66 EVT-treated patients were included in our study. MMI occurred in 27 patients (41%). In unadjusted analysis, successful reperfusion was associated with fewer MMIs (31.8% vs. 65.0%; P = 0.015) and with more favorable outcome at 3 months (50% vs. 20%; P = 0.023). In multivariate analysis, successful reperfusion was associated with an adjusted odds ratio (95% confidence intervals) of 0.35 (0.10-1.12) for MMI and 2.77 (0.84-10.43) for 3-month favorable outcome occurrence.

CONCLUSIONS

Early successful reperfusion performed in patients with AIS with clinical and imaging predictors of MMI was associated with decreased MMI occurrence. Reperfusion status might be considered in evaluating the need for craniectomy in patients with early predictors of MMI.

Boundary and vulnerability estimation of the internal borderzone using ischemic stroke lesion mapping

Distinction between deep and superficial middle cerebral artery (MCA) territories and their junctional vascular area (the internal borderzone or IBZ) constitutes a predictor of stroke patient outcome. However, the IBZ boundaries are not well-defined because of substantial anatomical variance. Here, we built a statistical estimate of the IBZ and tested its vulnerability to ischemia using an independent sample. First, we used delineated lesions of 122 patients suffering of chronic ischemic stroke grouped in deep, superficial and territorial topographies and statistical comparisons to generate a probabilistic estimate of the IBZ. The IBZ extended from the insular cortex to the internal capsule and the anterior part of the caudate nucleus head. The IBZ showed the highest lesion frequencies (~30% on average across IBZ voxels) in our chronic stroke patients but also in an independent sample of 87 acute patients. Additionally, the most important apparent diffusion coefficient reductions (−6%), which reflect stroke severity, were situated within our IBZ estimate. The IBZ was most severely injured in case of a territorial infarction. Then, our results are in favour of an increased IBZ vulnerability to ischemia. Moreover, our probabilistic estimates of deep, superficial and IBZ regions can help the everyday spatial classification of lesions.

Thrombectomy for Stroke at 6-24 hours without Perfusion CT Software for Patient Selection

BACKGROUND

Although, thrombectomy for stroke more than 6 hours after onset supported by automated perfusion computed tomography (CT) software (RAPID, iSchemaView) is effective, this software is not available in Japan. This study aimed to elucidate the efficacy of thrombectomy 6-24 hours after onset in our patient cohort using conventional imaging mismatch.

METHODS

Of 586 ischemic stroke patients who underwent thrombectomy registered from January 2015 to December 2017, patients with occlusion of the intracranial internal carotid artery or middle cerebral artery, who had last been known to be well 6-24 hours earlier and who had a prestroke modified Rankin scale (mRS) score 0 or 1 were enrolled. Clinical outcomes were the scores of the utility-weighted (UW) mRS, which ranges from 0 (death) to 10 (no symptom or disability), and the rate of functional independence (mRS score of 0-2) at 90 days.

RESULTS

This study sample included 31 patients. The median baseline National Institutes of Health Stroke Scale score was 17 (interquartile range [IQR], 13-20), and the median Diffusion-Weighted Imaging-Alberta Stroke Program Early CT Score was 7 (IQR, 5-8). The median interval between the time that the patient was last known well and revascularization was 741 (IQR, 641-818) minutes. The mean UW mRS score at 90 days was 5.3, the rate of functional independence was 32%, and the 90-day mortality rate was 13%.

CONCLUSIONS

Thrombectomy 6-24 hours after onset which can be performed with conventional imaging mismatch might be secured for improving functional independence in stroke patients.

Mechanical Thrombectomy-A Brief Review of a Revolutionary new Treatment for Thromboembolic Stroke

The recent success of endovascular stroke treatment has heralded a new era in the management of acute ischemic stroke (AIS) with significantly improved outcome for patients. A large number of patients may be amenable to this new treatment and as the evidence expands the number of patients eligible for mechanical thrombectomy continues to increase. Recent evidence suggests that the time window for treatment can be extended up to 24 h after symptom onset for patients with anterior circulation strokes; however, many clinicians and medical professionals may not be aware of these recent changes and it is important that they are kept up-to-date with this rapidly evolving treatment. This review provides an overview of the recent successful trials and highlights important steps that should be instituted in order to achieve rapid reperfusion and optimize the outcome for ischemic stroke patients. It also looks at the remaining controversies facing the field of thrombectomy. A short summary of each of these contentious areas is provided and the current state of the art.

Impact of Lesion Load Thresholds on Alberta Stroke Program Early Computed Tomographic Score in Diffusion-Weighted Imaging

Background and aims

Assessment of ischemic lesions on computed tomography or MRI diffusion-weighted imaging (DWI) using the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is widely used to guide acute stroke treatment. However, it has never been defined how many voxels need to be affected to label a DWI-ASPECTS region ischemic. We aimed to assess the effect of various lesion load thresholds on DWI-ASPECTS and compare this automated analysis with visual rating.

Materials and methods

We analyzed overlap of individual DWI lesions of 315 patients from the previously published predictive value of fluid-attenuated inversion recovery study with a probabilistic ASPECTS template derived from 221 CT images. We applied multiple lesion load thresholds per DWI-ASPECTS region (>0, >1, >10, and >20% in each DWI-ASPECTS region) to compute DWI-ASPECTS for each patient and compared the results to visual reading by an experienced stroke neurologist.

Results

By visual rating, median ASPECTS was 9, 84 patients had a DWI-ASPECTS score ≤7. Mean DWI lesion volume was 22.1 (±35) ml. In contrast, by use of >0, >1-, >10-, and >20%-thresholds, median DWI-ASPECTS was 1, 5, 8, and 10; 97.1% (306), 72.7% (229), 41% (129), and 25.7% (81) had DWI-ASPECTS ≤7, respectively. Overall agreement between automated assessment and visual rating was low for every threshold used (>0%: κ_w = 0.020 1%: κ_w = 0.151; 10%: κ_w = 0.386; 20% κ_w = 0.381). Agreement for dichotomized DWI-ASPECTS ranged from fair to substantial (≤7: >10% κ = 0.48; >20% κ = 0.45; ≤5: >10% κ = 0.528; and >20% κ = 0.695).

Conclusion

Overall agreement between automated and the standard used visual scoring is low regardless of the lesion load threshold used. However, dichotomized scoring achieved more comparable results. Varying lesion load thresholds had a critical impact on patient selection by ASPECTS. Of note, the relatively low lesion volume and lack of patients with large artery occlusion in our cohort may limit generalizability of these findings.

The hemorrhagic transformation index score: a prediction tool in middle cerebral artery ischemic stroke

BACKGROUND

We aimed to develop a tool, the hemorrhagic transformation (HT) index (HTI), to predict any HT within 14 days after middle cerebral artery (MCA) stroke onset regardless of the intravenous recombinant tissue plasminogen activator (IV rtPA) use. That is especially important in the light of missing evidence-based data concerning the timing of anticoagulant resumption after stroke in patients with atrial fibrillation (AF).

METHODS

We retrospectively analyzed 783 consecutive MCA stroke patients. Clinical and brain imaging data at admission were recorded. A follow-up period was 2 weeks after admission. The patients were divided into derivation (DC) and validation (VC) cohorts by generating Bernoulli variates with probability parameter 0.7. Univariate/multivariate logistic regression, and factor analysis were used to extract independent predictors. Validation was performed with internal consistency reliability and receiver operating characteristic (ROC) analysis. Bootstrapping was used to reduce bias.

RESULTS

The HTI was composed of 4 items: Alberta Stroke Program Early CT score (ASPECTS), National Institutes of Health Stroke Scale (NIHSS), hyperdense MCA (HMCA) sign, and AF on electrocardiogram (ECG) at admission. According to the predicted probability (PP) range, scores were allocated to ASPECTS as follows: 10-7 = 0; 6-5 = 1; 4-3 = 2; 2-0 = 3; to NIHSS: 0-11 = 0; 12-17 = 1; 18-23 = 2; >23 = 3; to HMCA sign: yes = 1; to AF on ECG: yes = 1. The HTI score varied from 0 to 8. For each score, adjusted PP of any HT with 95% confidence intervals (CI) was as follows: 0 = 0.027 (0.011-0.042); 1 = 0.07 (0.043-0.098); 2 = 0.169 (0.125-0.213); 3 = 0.346 (0.275-0.417); 4 = 0.571 (0.474-0.668); 5 = 0.768 (0.676-0.861); 6 = 0.893 (0.829-0.957); 7 = 0.956 (0.92-0.992); 8 = 0.983 (0.965-1.0). The optimal cutpoint score to differentiate between HT-positive and negative groups was 2 (95% normal-based CI, 1-3) for the DC and VC alike. ROC area/sensitivity/specificity with 95% normal-based CI for the DC and VC were 0.85 (0.82-0.89)/0.82 (0.73-0.9)/0.89 (0.8-0.97) and 0.83 (0.78-0.88)/0.8 (0.66-0.94)/0.87 (0.73-1.0) respectively. McDonald's categorical omega with 95% bias-corrected and accelerated CI for the DC and VC was 0.81 (0.77-0.84) and 0.82 (0.76-0.86) respectively.

CONCLUSIONS

The HTI is a simple yet reliable tool to predict any HT within 2 weeks after MCA stroke onset regardless of the IV rtPA use.

ASPECTS CT in Acute Ischemia: Review of Current Data

The Alberta Stroke Program Early CT score (ASPECTS) is a 10-point semiquantitative topographic scoring system developed for the assessment of early ischemic changes (EICs) on noncontrast-enhanced computed tomography (NCCT) in patients with acute ischemic stroke involving the middle cerebral artery (MCA) territory. One point is subtracted from a total score of 10, if an EIC is present in any part of each of the ASPECTS regions. Higher ASPECTS has been associated with better outcomes and a lower risk of symptomatic intracerebral hemorrhage. To date, there are still controversies regarding the utility of ASPECTS for selecting patients for intravenous and intra-arterial therapies. This article provides a comprehensive review regarding methodology, limitations, and interobserver reproducibility of ASPECTS, as well as application of ASPECTS in clinical care. The focus of this review is ASPECTS evaluation on NCCT. The application of ASPECTS on multimodal computed tomography and magnetic resonance imaging (MRI) is briefly described.

Successful Reperfusion With Mechanical Thrombectomy Is Associated With Reduced Disability and Mortality in Patients With Pretreatment Diffusion-Weighted Imaging–Alberta Stroke Program Early Computed Tomography Score ≤6

Background and Purpose—

In acute ischemic stroke patients, diffusion-weighted imaging (DWI)–Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is correlated with infarct volume and is an independent factor of functional outcome. Patients with pretreatment DWI-ASPECTS ≤6 were excluded or under-represented in the recent randomized mechanical thrombectomy trials. Our aim was to assess the impact of reperfusion in pretreatment DWI-ASPECTS ≤6 patients treated with mechanical thrombectomy.

Methods—

We analyzed data collected between January 2012 and August 2015 in a bicentric prospective clinical registry of consecutive acute ischemic stroke patients treated with mechanical thrombectomy. Every patient with a documented internal carotid artery or middle cerebral artery occlusion with pretreatment DWI-ASPECTS ≤6 was eligible for this study. The primary end point was a favorable outcome defined by a modified Rankin Scale score ≤2 at 90 days.

Results—

Two hundred and eighteen patients with a DWI-ASPECTS ≤6 were included. Among them, 145 (66%) patients had successful reperfusion at the end of mechanical thrombectomy. Reperfused patients had an increased rate of favorable outcome (38.7% versus 17.4%; P =0.002) and a decreased rate of mortality at 3 months (22.5% versus 39.1%; P =0.013) compared with nonreperfused patients. The symptomatic intracranial hemorrhage rate was not different between the 2 groups (13.0% versus 14.1%; P =0.83). However, in patients with DWI-ASPECTS <5, favorable outcome was low (13.0% versus 9.5%; P =0.68) with a high mortality rate (45.7% versus 57.1%; P =0.38) with or without successful reperfusion.

Conclusions—

Successful reperfusion is associated with reduced mortality and disability in patients with a pretreatment DWI-ASPECTS ≤6. Further data from randomized studies are needed, particularly in patients with DWI-ASPECTS <5.

Mechanical thrombectomy in acute ischemic stroke

Recent randomized trials have demonstrated the efficacy of stent retriever thrombectomy, in association with intravenous thrombolysis, in acute ischemic stroke related to the occlusion of the distal internal carotid artery or the proximal middle cerebral artery within six hours of symptom onset. Mechanical thrombectomy should be performed as soon as possible after symptom onset. High age alone should not be considered as a contraindication for mechanical thrombectomy. Mechanical thrombectomy is recommended in acute ischemic stroke patients with large vessel occlusions and salvageable brain tissue if intravenous thrombolysis is contraindicated. Re-organization of stroke care systems is needed to provide rapid access to endovascular therapy equitably to all eligible patients.

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.

Towards an understanding of regulating Cajal body activity by protein modification

The biogenesis of small nuclear ribonucleoproteins (snRNPs), small Cajal body-specific RNPs (scaRNPs), small nucleolar RNPs (snoRNPs) and the telomerase RNP involves Cajal bodies (CBs). Although many components enriched in the CB contain post-translational modifications (PTMs), little is known about how these modifications impact individual protein function within the CB and, in concert with other modified factors, collectively regulate CB activity. Since all components of the CB also reside in other cellular locations, it is also important that we understand how PTMs affect the subcellular localization of CB components. In this review, we explore the current knowledge of PTMs on the activity of proteins known to enrich in CBs in an effort to highlight current progress as well as illuminate paths for future investigation.

ASPECTS (Alberta Stroke Program Early CT Score) Assessment of the Perfusion-Diffusion Mismatch

BACKGROUND AND PURPOSE

Rapid and reliable assessment of the perfusion-weighted imaging (PWI)/diffusion-weighted imaging (DWI) mismatch is required to promote its wider application in both acute stroke clinical routine and trials. We tested whether an evaluation based on the Alberta Stroke Program Early CT Score (ASPECTS) reliably identifies the PWI/DWI mismatch.

METHODS

A total of 232 consecutive patients with acute middle cerebral artery stroke who underwent pretreatment magnetic resonance imaging (PWI and DWI) were retrospectively evaluated. PWI-ASPECTS and DWI-ASPECTS were determined blind from manually segmented PWI and DWI volumes. Mismatch-ASPECTS was defined as the difference between PWI-ASPECTS and DWI-ASPECTS (a high score indicates a large mismatch). We determined the mismatch-ASPECTS cutoff that best identified the volumetric mismatch, defined as VolumeTmax>6s/VolumeDWI≥1.8, a volume difference≥15 mL, and a VolumeDWI<70 mL.

RESULTS

Inter-reader agreement was almost perfect for PWI-ASPECTS (κ=0.95 [95% confidence interval, 0.90-1]), and DWI-ASPECTS (κ=0.96 [95% confidence interval, 0.91-1]). There were strong negative correlations between volumetric and ASPECTS-based assessments of DWI lesions (ρ=-0.84, P<0.01) and PWI lesions (ρ=-0.90, P<0.01). Receiver operating characteristic curve analysis showed that a mismatch-ASPECTS ≥2 best identified a volumetric mismatch, with a sensitivity of 0.93 (95% confidence interval, 0.89-0.98) and a specificity of 0.82 (95% confidence interval, 0.74-0.89).

CONCLUSIONS

The mismatch-ASPECTS method can detect a true mismatch in patients with acute middle cerebral artery stroke. It could be used for rapid screening of patients with eligible mismatch, in centers not equipped with ultrafast postprocessing software.

Endovascular thrombectomy for stroke: current best practice and future goals

Endovascular thrombectomy for large vessel ischaemic stroke substantially reduces disability, with recent positive randomised trials leading to guideline changes worldwide. This review discusses in detail the evidence provided by recent randomised trials and meta-analyses, the remaining areas of uncertainty and the future directions for research. The data from existing trials have demonstrated the robust benefit of endovascular thrombectomy for internal carotid and proximal middle cerebral artery occlusions. Uncertainty remains for more distal occlusions where the efficacy of alteplase is greater, less tissue is at risk and the safety of endovascular procedures is less established. Basilar artery occlusion was excluded from the trials, but with a dire natural history and proof of principle that rapid reperfusion is effective, it seems reasonable to continue treating these patients pending ongoing trial results. There has been no evidence of heterogeneity in treatment effect in clinically defined subgroups by age, indeed, those aged >80 years have at least as great an overall reduction in disability and reduced mortality. Similarly there was no heterogeneity across the range of baseline stroke severities included in the trials. Evidence that routine use of general anaesthesia reduces the benefit of endovascular thrombectomy is increasing and conscious sedation is generally preferred unless severe agitation or airway compromise is present. The impact of time delays has become clearer with description of onset to imaging and imaging to reperfusion epochs. Delays in the onset to imaging reduce the proportion of patients with salvageable brain tissue. However, in the presence of favourable imaging, rapid treatment appears beneficial regardless of the onset to imaging time elapsed. Imaging to reperfusion delays lead to decay in the clinical benefit achieved, particularly in those with less robust collateral flow. The brain imaging options to assess prognosis have various advantages and disadvantages, but whatever strategy is employed must be fast. Ongoing trials are investigating extended time windows, using advanced brain imaging selection. There is also a need for further technical advances to maximise rates of complete reperfusion in the minimum time.

Outcomes Are Not Different between Patients with Intermediate and High DWI-ASPECTS after Stent-Retriever Embolectomy for Acute Anterior Circulation Stroke

BACKGROUND AND PURPOSE

Questions remain as to what benefits embolectomy provides to patients presented with considerable early ischemic changes on baseline imaging studies. This study aimed to investigate the impact of the Alberta Stroke Program Early CT Score applied to DWI on treatment outcomes in patients with acute stroke undergoing stent-retriever embolectomy.

MATERIALS AND METHODS

We retrospectively analyzed the clinical and DWI data from 171 patients with acute anterior circulation stroke who were treated with stent-retriever embolectomy within 6 hours of symptom onset. DWI-ASPECTS scores were analyzed with the full scale or were dichotomized (4-6 versus 7-10). Patients with DWI-ASPECTS ≤3 were excluded from the study. Associations between outcome and clinical and radiologic factors were determined with a multivariate logistic regression analysis. A good outcome was defined as a modified Rankin Scale score of 0-2 at 3 months.

RESULTS

The median DWI-ASPECTS was 7 (interquartile range, 6-8). The rates of good outcome, symptomatic hemorrhage, and mortality were not different between high DWI-ASPECTS (scores of 7-10) and intermediate DWI-ASPECTS (scores of 4-6) groups. In patients with an intermediate DWI-ASPECTS, good outcome was achieved in 46.5% (20/43) of patients with successful revascularization, whereas no patients without successful revascularization had a good outcome (P = .016). In multivariate logistic regression analysis, independent predictors of good outcome were age and successful revascularization.

CONCLUSIONS

Our study suggested that there were no differences in outcomes between patients with a high DWI-ASPECTS and those with an intermediate DWI-ASPECTS who underwent stent-retriever embolectomy for acute anterior circulation stroke. Thus, patients with an intermediate DWI-ASPECTS otherwise eligible for endovascular therapy may not be excluded from stent-retriever embolectomy or stroke trials.

[Imaging-based indications for interventional treatment of stroke]

The indications for mechanical thrombectomy are based on a proximal vessel occlusion in the absence of extensive ischemic damage in the corresponding dependent vascular territory. The maximum extent of early ischemic edema for which endovascular treatment is still useful is not clear from the studies. A benefit of mechanical thrombectomy can be safely assumed with an ASPECT score of 6-10, possibly also with lower scores. A more complex imaging with assessment of the status of collateral vessels or perfusion abnormality is scientifically interesting but usually not necessary for clinical decision-making for endovascular stroke treatment within the first 6 h after symptom onset.