Differential Effect of Baseline Computed Tomographic Angiography Collaterals on Clinical Outcome in Patients Enrolled in the Interventional Management of Stroke III Trial

The impacts of venous outflow profiles on outcomes among large vessel occlusion patients receiving endovascular treatment in the late window

OBJECTIVES

To investigate the association between venous outflow (VO) profiles and outcomes among acute ischemic stroke caused by anterior circulation large vessel occlusion (AIS-LVO) patients who had undergone endovascular treatment (EVT) in the late window of 6-24 h from stroke onset.

METHODS

This was a post-hoc analysis of our preceding RESCUE-BT trial, with findings validated in an external cohort. Baseline computed tomographic angiography (CTA) was performed to assess VO using the Cortical Vein Opacification Score (COVES). The primary clinical outcome was functional independence at 90 days (modified Rankin Scale score of 0-2). The adjusted odd ratio (aOR) and confidence interval (CI) were obtained from multivariable logistic regressions.

RESULTS

A total of 440 patients were included in the present study. After identifying the cutoff of COVES by marginal effects approach, enrolled patients were divided into the favorable VO group (COVES 4-6) and the poor VO (COVES 0-3) group. Multivariable logistic regression analysis showed that favorable VO (aOR 2.25; 95% CI 1.31-3.86; p = 0.003) was associated with functional independence. Similar results were detected in the external validation cohort. Among those with poor arterial collateralization, favorable VO was still an independent predictor of functional independence (aOR 2.09; 95% CI 1.06-4.10; p = 0.032).

CONCLUSION

The robust VO profile indicated by COVES 4-6 could promote the frequency of functional independence among AIS-LVO patients receiving EVT in the late window, and the prognostic value of VO was independent of the arterial collateral status.

CLINICAL RELEVANCE STATEMENT

The robust venous outflow profile was a valid predictor for functional independence among AIS-LVO patients receiving EVT in the late window (6-24 h) and the predictive role of venous outflow did not rely on the status of arterial collateral circulation.

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.

Predicting 3-month Functional Outcome After Endovascular Thrombectomy in Patients with Anterior Circulation Occlusion with an Arterial Transit Artifact Grading System

PURPOSE

The objective of this study was to evaluate the relationship between arterial transit artifact (ATA), arterial spin labeling (ASL) perfusion imaging, and the outcome of patients with acute ischemic stroke (AIS) due to occlusion of large vessels in anterior circulation after endovascular thrombectomy (EVT).

METHODS

Patients with anterior circulation occlusion treated with EVT between October 2017 and December 2021 were enrolled in this retrospective study, and ATA was quantified by a 4-point scale. A favorable outcome was defined by modified Rankin Scale (mRS) scores of 0-2 at 3 months. To identify independent predictors of favorable outcome, age, sex, risk factors, baseline National Institutes of Health Stroke Scale (NIHSS) score, site of occlusion, cause of stroke, and early reperfusion were evaluated with univariate and multivariate analyses. Predictive accuracy was evaluated by calculating the area under the receiver operating characteristic (ROC) curve (AUC) for the model.

RESULTS

In this study 187 patients (age, 65.0 ± 12.5 years; men, 55%) were evaluated. Younger age (odds ratio, OR, 0.95; 95% confidence interval, CI, 0.92-0.98, p = 0.002), lower baseline NIHSS score (OR, 0.88; 95% CI, 0.82-0.94, p < 0.001), and lower ATA score (OR, 1.14; 95% CI, 1.06-1.22, p < 0.001) were independently associated with favorable outcomes in multivariate analysis. The ATA score has moderate to good accuracy in predicting favorable outcomes (AUC, 0.753).

CONCLUSION

A high ATA score as a potential predictor, can help identify patients who may benefit from EVT.

Siamese model for collateral score prediction from computed tomography angiography images in acute ischemic stroke

Introduction

Imaging biomarkers, such as the collateral score as determined from Computed Tomography Angiography (CTA) images, play a role in treatment decision making for acute stroke patients. In this manuscript, we present an end-to-end learning approach for automatic determination of a collateral score from a CTA image. Our aim was to investigate whether such end-to-end learning approaches can be used for this classification task, and whether the resulting classification can be used in existing outcome prediction models.

Methods

The method consists of a preprocessing step, where the CTA image is aligned to an atlas and divided in the two hemispheres: the affected side and the healthy side. Subsequently, a VoxResNet based convolutional neural network is used to extract features at various resolutions from the input images. This is done by using a Siamese model, such that the classification is driven by the comparison between the affected and healthy using a unique set of features for both hemispheres. After masking the resulting features for both sides with the vascular region and global average pooling (per hemisphere) and concatenation of the resulting features, a fully connected layer is used to determine the categorized collateral score.

Experiments

Several experiments have been performed to optimize the model hyperparameters and training procedure, and to validate the final model performance. The hyperparameter optimization and subsequent model training was done using CTA images from the MR CLEAN Registry, a Dutch multi-center multi-vendor registry of acute stroke patients that underwent endovascular treatment. A separate set of images, from the MR CLEAN Trial, served as an external validation set, where collateral scoring was assessed and compared with both human observers and a recent more traditional model. In addition, the automated collateral scores have been used in an existing functional outcome prediction model that uses both imaging and non-imaging clinical parameters.

Conclusion

The results show that end-to-end learning of collateral scoring in CTA images is feasible, and does perform similar to more traditional methods, and the performance also is within the inter-observer variation. Furthermore, the results demonstrate that the end-to-end classification results also can be used in an existing functional outcome prediction model.

Pretreatment CT perfusion collateral parameters correlate with penumbra salvage in middle cerebral artery occlusion

BACKGROUND AND PURPOSE

Acute ischemic stroke due to large vessel occlusion (AIS-LVO) is a major cause of functional dependence. Collateral status (CS) is an important determinant of functional outcomes. Pretreatment CT perfusion (CTP) parameters serve as reliable surrogates of CS. Penumbra Salvage Index (PSI) is another parameter predictive of functional outcomes in AIS-LVO. The aim of this study is to assess the relationship of pretreatment CTP parameters with PSI.

METHODS

In this prospectively collected, retrospectively reviewed multicenter analysis, inclusion criteria were as follows: (1) CT angiography confirmed middle cerebral artery (MCA) M1-segment and proximal M2-segment occlusion from 9/1/2017 to 9/22/2022; (2) diagnostic CTP; and (3) available diagnostic Magnetic resonance Imaging (MRI) diffusion-weighted images. Pearson correlation analysis was performed to assess the association between cerebral blood volume (CBV) index and hypoperfusion intensity ratio (HIR) with PSI. p value ≤.05 was considered statistically significant.

RESULTS

In total, 131 patients (n = 86, M1 and n = 45, proximal M2 occlusion) met our inclusion criteria. CBV index showed a modest positive correlation with PSI (r = 0.34, p<.001) in patients with proximal MCA occlusion. Similar trends were noted in subgroup analysis of patients with M1 occlusion, and proximal M2 occlusion. Whereas, HIR did not have a strong trend or correlation with PSI.

CONCLUSION

CBV index correlates with PSI, whereas HIR does not. Future studies are needed to expand our understanding of the adjunct role of CBV index with other similar pretreatment CTP-based markers in clinical evaluation and decision-making in patients with MCA occlusion.

Impact of Collateral Circulation on Futile Endovascular Thrombectomy in Acute Anterior Circulation Ischemic Stroke

OBJECTIVE

Collateral circulation is associated with the differential treatment effect of endovascular thrombectomy (EVT) in acute ischemic stroke. We aimed to verify the ability of the collateral map to predict futile EVT in patients with acute anterior circulation ischemic stroke.

METHODS

This secondary analysis of a prospective observational study included data from participants underwent EVT for acute ischemic stroke due to occlusion of the internal carotid artery and/or the middle cerebral artery within 8 hours of symptom onset. Multiple logistic regression analyses were conducted to identify independent predictors of futile recanalization (modified Rankin scale score at 90 days of 4-6 despite of successful reperfusion).

RESULTS

In a total of 214 participants, older age (odds ratio [OR], 2.40; 95% confidence interval [CI], 1.56 to 3.67; p<0.001), higher baseline National Institutes of Health Stroke Scale (NIHSS) scores (OR, 1.12; 95% CI, 1.04 to 1.21; p=0.004), very poor collateral perfusion grade (OR, 35.09; 95% CI, 3.50 to 351.33; p=0.002), longer door-to-puncture time (OR, 1.08; 95% CI, 1.02 to 1.14; p=0.009), and failed reperfusion (OR, 3.73; 95% CI, 1.30 to 10.76; p=0.015) were associated with unfavorable functional outcomes. In 184 participants who achieved successful reperfusion, older age (OR, 2.30; 95% CI, 1.44 to 3.67; p<0.001), higher baseline NIHSS scores (OR, 1.12; 95% CI, 1.03 to 1.22; p=0.006), very poor collateral perfusion grade (OR, 4.96; 95% CI, 1.42 to 17.37; p=0.012), and longer door-to-reperfusion time (OR, 1.09; 95% CI, 1.03 to 1.15; p=0.003) were associated with unfavorable functional outcomes.

CONCLUSION

The assessment of collateral perfusion status using the collateral map can predict futile EVT, which may help select ineligible patients for EVT, thereby potentially reducing the rate of futile EVT.

Deep Learning-Based Synthetic TOF-MRA Generation Using Time-Resolved MRA in Fast Stroke Imaging

BACKGROUND AND PURPOSE

Time-resolved MRA enables collateral evaluation in acute ischemic stroke with large-vessel occlusion; however, a low SNR and spatial resolution impede the diagnosis of vascular occlusion. We developed a CycleGAN-based deep learning model to generate high-resolution synthetic TOF-MRA images using time-resolved MRA and evaluated its image quality and clinical efficacy.

MATERIALS AND METHODS

This retrospective, single-center study included 397 patients who underwent both TOF- and time-resolved MRA between April 2021 and January 2022. Patients were divided into 2 groups for model development and image-quality validation. Image quality was evaluated qualitatively and quantitatively with 3 sequences. A multireader diagnostic optimality evaluation was performed by 16 radiologists. For clinical validation, we evaluated 123 patients who underwent fast stroke MR imaging to assess acute ischemic stroke. The diagnostic confidence level and decision time for large-vessel occlusion were also evaluated.

RESULTS

Median values of overall image quality, noise, sharpness, venous contamination, and SNR for M1, M2, the basilar artery, and posterior cerebral artery are better with synthetic TOF than with time-resolved MRA. However, with respect to real TOF, synthetic TOF presents worse median values of overall image quality, sharpness, vascular conspicuity, and SNR for M3, the basilar artery, and the posterior cerebral artery. During the multireader evaluation, radiologists could not discriminate synthetic TOF images from TOF images. During clinical validation, both readers demonstrated increases in diagnostic confidence levels and decreases in decision time.

CONCLUSIONS

A CycleGAN-based deep learning model was developed to generate synthetic TOF from time-resolved MRA. Synthetic TOF can potentially assist in the detection of large-vessel occlusion in stroke centers using time-resolved MRA.

Prognostic Value of Venous Outflow Profiles on Multiphase CT Angiography for the Patients with Acute Ischemic Stroke After Endovascular Thrombectomy

To evaluate the prognostic value of venous outflow (VO) profiles evaluated on multiphase CTA (mCTA) for the patients with acute ischemic stroke (AIS) after endovascular thrombectomy (EVT). We retrospectively collected 150 patients with AIS who underwent pre-treatment CT perfusion (CTP) evaluation and subsequent EVT from April 2018 to April 2022. Three-phases (peak arterial phase, peak venous phase, late venous phase) CTA was reconstructed from CTP raw data, and VO was evaluated on three-phases CTA, respectively. Favorable VO was regarded as a cortical vein opacification score of 3-6, and unfavorable VO as a score of 0-2. Good outcome was defined as modified Rankin Scale score of 0-2 at 90 days after EVT. Multivariate logistic regression analysis was performed to explore the predictors of good outcome. Prognostic value was assessed and compared using receiver operating characteristic (ROC) curves and Delong test. We found that good outcome was achieved in 85 (56.7%) patients. Among the mCTA-derived VO profiles, only favorable peak venous phase VO was found to be independently associated with good outcome (P < 0.001). After integrating favorable peak venous phase VO with lower post-treatment National Institute of Health Stroke Scale score at 24 hours, successful recanalization and favorable hypoperfusion intensity ratio, the predictive ability for a good outcome was significantly improved than before (area under the ROC curve; 0.947 vs 0.881; P = 0.002). This study supports that favorable peak venous VO profiles on mCTA might be a promising biomarker in predicting the good outcome in patients with AIS after EVT.

Parenchymal Blood Volume Changes Immediately After Endovascular Thrombectomy Predict Futile Recanalization in Patients with Emergent Large Vessel Occlusion

OBJECTIVE

More than one third of acute ischemic stroke (AIS) patients do not recover to functional independence even if endovascular thrombectomy (EVT) is performed rapidly and successfully. This suggests that angiographic recanalization does not necessarily lead to tissue reperfusion. Although recognition of reperfusion status after EVT is pivotal for optimal postoperative management, reperfusion imaging assessment immediately after recanalization has not been fully investigated. The present study aimed to evaluate whether reperfusion status based on parenchymal blood volume (PBV) assessment after angiographic recanalization influences infarct growth and functional outcome in patients who have undergone EVT following AIS.

METHODS

Seventy-nine patients who underwent successful EVT for AIS were retrospectively analyzed. PBV maps were acquired from flat-panel detector computed tomography (CT) perfusion images before and after angiographic recanalization. Reperfusion status was assessed from PBV values and their changes in regions of interest and collateral score.

RESULTS

Post-EVT PBV ratio and ΔPBV ratio, as PBV parameters indicating the degree of reperfusion, were significantly lower in the unfavorable prognosis group (P < 0.01 each). Poor reperfusion on PBV mapping was associated with significantly longer puncture-to-recanalization time, lower collateral score, and higher frequency of infarct growth. Logistic regression analysis identified low collateral score and low ΔPBV ratio as associated with poor prognosis after EVT (odds ratios, 2.48, 3.72; 95% confidence intervals, 1.06-5.81, 1.20-11.53; P = 0.04, 0.02, respectively).

CONCLUSIONS

Poor reperfusion in severely hypoperfused territories on PBV mapping immediately after recanalization may predict infarct growth and unfavorable prognosis in patients who undergo EVT following AIS.

Pivotal role of multiphase computed tomography angiography for collateral assessment in patients with acute ischemic stroke

The cerebral collateral circulation is the main compensatory mechanism that maintains the ischemic penumbra viable, the tissue at risk for infarction that can be saved if blood flow is restored by reperfusion therapies. In clinical practice, the extent of collateral vessels recruited after vessel occlusion can be easily assessed with computed tomography angiography (CTA) using two different techniques: single-phase CTA (sCTA) and multi-phase CTA (mCTA). Both these methodologies have demonstrated a high prognostic predictive value for prognosis due to the strong association between the presence of good collaterals and favorable radiological and clinical outcomes in patients with acute ischemic stroke (AIS). However, mCTA seems to be superior to sCTA in the evaluation of collaterals and a promising tool for identifying AIS patients who can benefit from reperfusion therapies. In particular, it has recently been proposed the use of mCTA eligibility criteria has been recently proposed for the selection of AIS patients suitable for endovascular treatment instead of the current accepted criteria based on CT perfusion. In this review, we analyzed the characteristics, advantages and disadvantages of sCTA and mCTA to better understand their fields of application and the potential of mCTA in becoming the method of choice to assess collateral extent in AIS patients.

Oxidation‑reduction potential parameters worsen following intraarterial therapy in patients with reduced collateral circulation and middle cerebral artery occlusions

Collateral circulation is important for cerebral perfusion in acute ischemic strokes. Monitoring the oxidation-reduction potential (ORP) may be useful to assess collateral status or treatment efficacy. The objectives of the present study were to determine if the ORP was associated with collateral circulation status in middle cerebral artery (MCA) occlusions and to identify patterns in the ORP and the collateral circulation status among patients treated with intraarterial therapy (IAT) over time. The present pilot study was nested within a prospective cohort study measuring the ORP of the peripheral venous plasma of stroke patients. The population included in the present study were patients with MCA (M1/M2) occlusions. Two ORP parameters were examined: Static ORP (sORP; mV), indicating oxidative stress, and capacity ORP (cORP; µC), indicating antioxidant reserves. Collateral status was retrospectively graded using Miteff's system as good (grade 1) or reduced (grade 2/3). Comparisons were made between collateral status groups (reduced vs. good collaterals) in all patients, within a subset including only patients who received IAT, and between thrombolysis in cerebral infraction scale score (TICI) groups (0-2a vs. 2b/3). The Fisher's exact test, Student's t-test and Wilcoxon tests were used (α<0.20). The 19 patients were categorized based on their collaterals: Good collaterals (53%) and reduced collaterals (47%). The baseline characteristics were similar with the exception that the patients with good collaterals had a lower international normalized ratio (P=0.12) and were more likely to have a stroke on the left side (P=0.18) or to have a mismatch (P=0.05). The admission sORP values were comparable (169.5 vs. 164.2 mV; P=0.65), as was admission cORP (P=0.73). When considering only the patients who received IAT (n=12), admission sORP (P=0.69) and cORP (P=0.90) were also statistically similar. On day 2, after IAT, both groups experienced a worsening in ORP measures; however, the patients with good collaterals had a significantly lower sORP (169.4 vs. 203.5 mV; P=0.02) and a higher cORP (0.2 vs. 0.1 µC; P=0.002) compared with the patients with reduced collaterals. Neither sORP nor cORP were significantly different between TICI score groups on admission or on day 2. Upon discharge, patients with a TICI of 2b-3 had a significantly better sORP (P=0.03) and cORP (P=0.12) compared with those with a TICI of 0-2a. In conclusion, upon patient admission, the ORP parameters were not significantly different between the collateral circulation status groups for MCA occlusions. The ORP parameters worsened after IAT regardless of the collateral circulation status; however, after IAT, on day 2, patients with good collaterals experienced less oxidative stress (sORP) and had higher antioxidant reserves (cORP) than patients with reduced collaterals.

Total Cerebral Small Vessel Disease Burden Predicts the Outcome of Acute Stroke Patients after Intra-Arterial Thrombectomy

INTRODUCTION

Various types of cerebral small vessel diseases (cSVD) markers commonly coexist. The neurological function outcome is affected by their combined effect. To investigate the effect of cSVD on intra-arterial thrombectomy (IAT), our study aimed at developing and testing a model with fusing a combination of multiple cSVD markers as total cSVD burden to predict the outcome of acute ischemic stroke (AIS) patients after IAT treatment.

METHODS

From October 2018 to March 2021, continuous AIS patients with IAT treatment were enrolled. We calculated the cSVD markers identified by magnetic resonance imaging. The outcomes of all patients were assessed according to the modified Rankin Scale (mRS) score at 90 days after stroke. The relationship between total cSVD burden and outcomes was analyzed by logistics regression analysis.

RESULTS

A total of 271 AIS patients were included in this study. The proportions of score 0∼4 in the total cSVD burden group (i.e., score 0, 1, 2, 3, and 4 groups) were 9.6%, 19.9%, 23.6%, 32.8%, and 14.0%, respectively. The higher the cSVD score, the more patients with a poor outcome. Heavier total cSVD burden (1.6 [1.01∼2.27]), diabetes mellitus (1.27 [0.28∼2.23]), and higher national institute of health stroke scale (NIHSS) on admission (0.15 [0.07∼0.23]) were associated with poor outcome. In the two Least Absolute Shrinkage and Selection Operator regression models, model 1 using age, duration from onset to reperfusion, Alberta stroke program early CT score (ASPECTS), NIHSS on admission, modified thrombolysis in cerebral infarction (mTICI) and total cSVD burden as variables perform well on predicting short-term outcome in area under curve (AUC) of 0.90. Model 2, including all of the variables above except cSVD, showed less predictive capability than model 1 (AUC 0.90 vs. 0.82, p = 0.045).

CONCLUSIONS

The total cSVD burden score was independently associated with the clinical outcomes of AIS patients after IAT treatment and it may be a reliable predictor for poor outcomes of AIS patients after IAT treatment.

Predictors of Futile Recanalization in Patients with Intracranial Atherosclerosis-Related Stroke Undergoing Endovascular Treatment

OBJECTIVE

The predictors of futile recanalization in patients with intracranial atherosclerosis (ICAS)-related stroke are not understood. This study aimed to identify the predictors of futile recanalization after endovascular treatment (EVT) in patients who experience an acute stroke caused by ICAS-related occlusion.

METHODS

We retrospectively reviewed the data of patients with ICAS-related stroke who underwent EVT from January 2018 to July 2021. Futile recanalization was defined as functional dependence (modified Rankin scale 3-6) despite successful reperfusion (modified Thrombolysis in Cerebral Infarction score of 2 b/3). Multivariate logistic regression analysis was used to determine the risk factors associated with futile recanalization. The receiver operating characteristic curve was used to examine the predictive value of the risk prediction model for futile recanalization.

RESULTS

Of the 87 patients enrolled, futile recanalization was observed in 32 (36.8%). Multivariate logistic analysis showed that older age (OR, 1.05; 95% CI, 1.01-1.10; P = 0.026), a higher National Institutes of Health Stroke Scale (NIHSS) score on admission (OR, 1.25; 95% CI, 1.08-1.45; P = 0.003), and poor collaterals (OR, 5.49; 95% CI, 1.70-17.79; P = 0.004) were independently associated with futile recanalization after EVT in patients with ICAS-related stroke. The receiver operating characteristic curve showed that the model in combination with age, admission NIHSS score, and collateral status could accurately predict futile recanalization in these patients (areas under the curve, 0.85; 95% CI, 0.76-0.92; P < 0.001).

CONCLUSIONS

Older age, higher NIHSS score on admission, and poor collaterals are predictors of futile recanalization in patients with ICAS-related stroke.

The impact of leptomeningeal collaterals in acute ischemic stroke: a systematic review and meta-analysis

OBJECTIVES

Leptomeningeal collaterals provide an alternate pathway to maintain cerebral blood flow in stroke to prevent ischemia, but their role in predicting the outcome is still unclear. So, our study aims at assessing the significance of collateral blood flow (CBF) in acute stroke.

METHODS

Electronic databases were searched under different MeSH terms from January 2000 to February 2019. Studies were included if there was available data on good and poor CBF in acute ischemic stroke (AIS). The clinical outcomes included were modified Rankin scale (mRS), recanalization, mortality, and symptomatic intracranial hemorrhage (sICH) at 90 days. Data was analyzed using a random-effect model.

RESULTS

A total of 47 studies with 8194 patients were included. Pooled meta-analysis revealed that there exist twofold higher likelihood of favorable clinical outcome (mRS ≤ 2) at 90 days with good CBF compared with poor CBF (RR: 2.27; 95% CI: 1.94-2.65; p < 0.00001) irrespective of the thrombolytic therapy [RR with IVT: 2.90; 95% CI: 2.14-3.94; p < 0.00001, and RR with IAT/EVT: 1.99; 95% CI: 1.55-2.55; p < 0.00001]. Moreover, there exists onefold higher probability of successful recanalization with good CBF (RR: 1.31; 95% CI: 1.15-1.49; p < 0.00001). However, there was 54% and 64% lower risk of sICH and mortality respectively in patients with good CBF in AIS (p < 0.00001).

CONCLUSIONS

The relative risk of favorable clinical outcome is more in patients with good pretreatment CBF. This could be explained due to better chances of recanalization combined with a lesser risk of intracerebral hemorrhage with good CBF status.

Correlation Between Pre-treatment Collateral Status and Short-Term Functional Outcome in Patients With Mild to Moderate Stroke After Reperfusion Therapy in a Local Primary Stroke Center in the Southwestern Part of Saudi Arabia

Background Stroke is a substantial cause of disability and mortality worldwide and is characterized by the sudden onset of acute neurological deficit. During acute ischemia, cerebral collateral circulations are crucial in preserving blood supply to the ischemic region. Recombinant tissue plasminogen activator (r-tPA) and endovascular mechanical thrombectomy (MT) are the primary standards of care for acute recanalization therapy. Methodology From August 2019 through December 2021, we enrolled patients treated in our local primary stroke center with anterior circulation acute ischemic stroke (AIS) treated with intravenous thrombolysis (IVT) with or without MT. Only patients diagnosed with mild to moderate anterior ischemic stroke, as measured by the National Institutes of Health Stroke Scale (NIHSS), were included in the study. The candidate patients underwent non-contrast CT scanning (NCCT) and CT angiography (CTA) at admission. The modified Rankin scale (mRS) was used to assess the functional outcome of the stroke. The modified Tan scale, graded on a scale of 0-3, was used to determine the collateral status. Results This study comprised a total of 38 patients who had anterior circulation ischemic strokes. The mean age was 34. 8±13. All patients received IVT; eight patients (21.1%) underwent MT following r-tPA. In 26.3% of cases, hemorrhagic transformation (HT), both symptomatic and asymptomatic, was evident. Thirty-three participants (86.8%) had a moderate stroke, whereas five participants (13.2%) had a minor stroke. With a P-value of 0.003, a poor collateral status on the modified Tan score is substantially associated with a short, poor functional outcome. Conclusion In our study, patients with mild to moderate AIS with good collateral scores at admission had better short-term outcomes. Patients with poor collaterals tend to present with a disturbed level of consciousness more than patients with good collaterals.

Comparison of Three Scores of Collateral Status for Their Association With Clinical Outcome: The HERMES Collaboration

BACKGROUND

Leptomeningeal collateral status on baseline computed tomographic angiography (CTA) is associated with clinical outcome after acute ischemic stroke treatment. However, assessment of collateral status is not uniform. To compare 3 different CTA collateral scores (CS) and imaging techniques about their association with clinical outcome.

METHODS

Pooled analysis of patient-level data from the Highly Effective Reperfusion Using Multiple Endovascular Devices collaboration. Patients with large vessel occlusion from 7 randomized controlled trials that compared endovascular thrombectomy with standard medical care were included. Three different CS (Tan CS, regional CS [rCS], and regional Alberta Stroke Program Early CT Score CS) and 2 imaging techniques (single-phase [sCTA] and multiphase/dynamic CTA) were evaluated. Functional independence (modified Rankin Scale score 0-2) at 3 months poststroke was the primary outcome. Furthermore, we assessed the effect of sCTA image acquisition time on collateral status assessment using an adjusted ordinal logistic regression model to obtain predicted values for the trichotomized rCS.

RESULTS

Among 1147 pooled patients, 948 (82.7%) had sCTA and 199 (17.3%) multiphase/dynamic CTA as baseline angiography. With all 3 collateral scales, better CSs were associated with better 3-month functional outcome. With sCTA images, the rCS (area under the curve [AUC] 0.63) and regional Alberta Stroke Program Early CT Score CS (AUC 0.62) better predicted functional outcome than the Tan CS (AUC 0.60, respectively; P<0.001 and P=0.02). With multiphase/dynamic CTA images, all collateral scales performed similarly in predicting functional outcome (rCS [AUC 0.61]; regional Alberta Stroke Program Early CT Score CS [AUC 0.61] versus Tan CS [AUC 0.61], respectively; P=0.93 and P=0.91). Overall, no endovascular thrombectomy treatment effect modification by collateral status (rCS) was demonstrated (P=0.41). sCTA timing independently influenced CS assessment. On earlier timed sCTA, the predicted proportions of scans with poor collaterals was higher and vice versa.

CONCLUSIONS

In this data set of highly selected patients with stroke, using a regional CS on sCTA likely allows for the most accurate prediction of functional outcome while on time-resolved CTA, the type of CS did not matter. Patients across all collateral grades benefit from endovascular thrombectomy. sCTA timing independently influenced CS assessment.

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

BACKGROUND AND PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Correlation between Hypoperfusion Intensity Ratio and Functional Outcome in Large-Vessel Occlusion Acute Ischemic Stroke: Comparison with Multi-Phase CT Angiography

Background and purpose: Previous studies have shown that Hypoperfusion Intensity Ratio (HIR) derived from Perfusion Imaging (PWI) associated with collateral status in large-vessel occlusion (LVO) acute ischemic stroke (AIS) and could predict the rate of collateral flow, speed of infarct growth, and clinical outcome after endovascular treatment (EVT). We hypothesized that HIR derived from CT Perfusion (CTP) imaging could relatively accurately predict the functional outcome in LVO AIS patients receiving different types of treatment. Methods: Imaging and clinical data of consecutive patients with LVO AIS were retrospectively reviewed. Multi-phase CT angiography (mCTA) scoring was performed by 2 blinded neuroradiologists. CTP images were processed using an automatic post-processing analysis software. Correlation between the HIR and the functional outcome was calculated using the Spearman correlation. The efficacy of the HIR and the CTA collateral scores for predicting prognosis were compared. The optimal threshold of the HIR for predicting favorable functional outcome was determined using receiver operating characteristic (ROC) curve analysis. Results: 235 patients with LVO AIS were included. Patients with favorable functional outcome had lower HIR (0.1 [interquartile range (IQR), 0.1−0.2]) vs. 0.4 (IQR, 0.4−0.5)) and higher mCTA collateral scores (3 [IQR, 3−4] vs. 3 [IQR, 2−3]; p < 0.001) along with smaller infarct core volume (2.1 [IQR, 1.0−4.5]) vs. (15.2 [IQR, 5.5−39.3]; p < 0.001), larger mismatch ratio (22.9 [IQR, 11.6−45.6]) vs. (5.8 [IQR, 2.6−14]); p < 0.001), smaller ischemic volume (59.0 [IQR, 29.7−89.2]) vs. (97.5 [IQR, 68.7−142.2]; p < 0.001), and smaller final infarct volume (12.6 [IQR, 7.5−18.4]) vs. (78.9 [IQR, 44.5−165.0]; p < 0.001) than those with unfavorable functional outcome. The HIR was significantly positively correlated with the functional outcome [r = 0.852; 95% confidence interval (CI): 0.813−0.884; p < 0.0001]. The receiver operating characteristic (ROC) analysis showed that the optimal threshold for predicting a favorable functional outcome was HIR ≤ 0.3 [area under the curve (AUC) 0.968; sensitivity 88.89%; specificity 99.21%], which was higher than the mCTA collateral score [AUC 0.741; sensitivity 82.4%; specificity 48.8%]. Conclusions: HIR was associated with the functional outcome of LVO AIS patients, and the correlation coefficient was higher than mCTA collateral score. HIR outperformed mCTA collateral score in predicting functional outcome.

Interplay between anemia parameters and collateral status in patients who undergo mechanical thrombectomy

INTRODUCTION

Anemia is associated with higher morbidity and mortality, but its association with acute ischemic stroke (AIS) is not well established. We aim to determine the association of five-day anemia parameters with clinical outcomes in patients with an AIS, depending on their pre-mechanical thrombectomy (MT) collateral status.

METHODS

We performed a retrospective chart review of patients who underwent MT at a comprehensive stroke center from 7/2014 to 12/2020. The patients were divided into good and poor collateral groups depending on their pre-MT collateral status. A blinded board-certified neuroradiologist used collateral grading scale of Maas ≥ 3 to designate good collaterals on the pre-MT CT Angiogram. A binary logistic regression analysis was performed, controlling for the baseline parameters, with the five-day anemia parameters as predictors. The outcomes were functional independence (mRS 0-2), mortality, and early neurological improvement.

RESULTS

A total of 220 met the inclusion criteria. 94 (42.72 %) patients had good collaterals, while 126 (57.27 %) patients had poor collaterals. In the multivariable analysis, for patients with good collaterals, the higher values of five-day mean Hb (12.41 ± 1.87 vs 11.32 ± 1.95; OR, 0.72; 95 % CI, 0.54-0.95; P 0.018), five-day mean HCT (37.43 ± 5.1 vs 34.35 ± 5.5; OR, 0.89; 95 % CI, 0.81-0.98; P 0.018) and lower values of the difference between peak and trough values of Hb (1.75 ± 1.15 vs 2.41 ± 1.35; OR, 1.71; 95 % CI, 1.07-2.74; P 0.025) were associated with functional independence. For patients with poor collaterals, there was no association between five-day mean Hb, mean HCT parameters with functional independence, lower mortality, and early neurological improvement.

CONCLUSION

Our study was suggestive of an association between higher mean values of Hb and HCT over a five-day period and good clinical outcomes in patients with good collaterals who undergo MT for an anterior circulation LVO. This association was not found in the poor collateral group.

Collateral Status and Clinical Outcomes after Mechanical Thrombectomy in Patients with Anterior Circulation Occlusion

Background. Successful mechanical thrombectomy (MT) requires reliable, noninvasive selection criteria. We aimed to investigate the association of collateral status and clinical outcomes after MT in patients with ischemic stroke due to anterior circulation occlusion. Methods. 109 patients with poor collaterals and 110 aged, sex-matched patients with good collaterals were enrolled in the study. Collateral circulation was estimated by the CT angiography with a 0–3 scale. The collateral status was categorized as poor collaterals (scores 0–1) and good collaterals (scores 2-3). The reperfusion was assessed by the modified Treatment in Cerebral Infarction scale (mTICI, score 0/1/2a/2b/3). The clinical outcomes included the scores on the modified Rankin scale (mRS, ranging from 0 to 6) and death 90 days after mechanical thrombectomy. Results. Patients with greater scores of collateral status were more likely to achieve successful reperfusion (mTICI 2b/3). Patients with good collaterals were significantly associated with a higher chance of achieving mRS of 0–1 at 90 days (adjusted ORs: 4.55; 95% CI: 3.17–7.24; and $P$  < 0.001) and a lower risk of death at 90 days (adjusted ORs: 0.87; 95% CI: 4.0%–28.0%; and $P$  = 0.012) compared to patients with poor collaterals. In subgroup analyses, patients with statin use seem to benefit more from the effect of collateral status on good mRS (≤2). Conclusion. Among patients with acute ischemic stroke caused by anterior circulation occlusion, better collateral status is associated with higher scores on mRS and lower mortality after mechanical thrombectomy. Statin use might have an interaction with the effect of collateral status.

Association of the Careggi Collateral Score with 3-month modified Rankin Scale score after thrombectomy for stroke with occlusion of the middle cerebral artery

BACKGROUND

The Careggi Collateral Score (CCS) (qualitative-quantitative evaluation) was developed from a single-centre cohort as an angiographic score to describe both the extension and effectiveness of the pial collateral circulation in stroke patients with occlusion of the anterior circulation. We aimed to examine the association between CCS (quantitative evaluation) and 3-month modified Rankin Scale (mRS) score in a large multi-center cohort of patients receiving thrombectomy for stroke with occlusion of middle cerebral artery (MCA).

METHODS

We conducted a study on prospectively collected data from 1284 patients enrolled in the Italian Registry of Endovascular Treatment in Acute Stroke. According to the extension of the retrograde reperfusion in the cortical anterior cerebral artery (ACA)-MCA territories, CCS ranges from 0 (absence of retrograde filling) to 4 (visualization of collaterals until the alar segment of the MCA).

RESULTS

Using CCS of 4 as reference, CCS grades were associated in the direction of unfavourable outcome on 3-month mRS shift (0 to 6); significant difference was found between CCS of 0 and CCS of 1 and between CCS of 3 and CCS of 4. CCS ≥ 3 was the optimal cut-off for predicting 3-month excellent outcome, while CCS ≥ 1 was the optimal cut-off for predicting 3-month survival. CCS of 0 and CCS < 3 were associated in the direction of unfavourable recanalization on TICI shift (0 to 3) compared with CCS ≥ 1 and CCS ≥ 3, respectively. Compared with CCS ≥ 3 as reference, CCS of 0 and CCS 1 to 2 were associated in the direction of unfavourable recanalization on TICI shift. There was no evidence of heterogeneity of effects of successful recanalization and procedure time ≤ 60 min on 3-month mRS shift across CCS categories.

CONCLUSION

The CCS could provide a future advantage for improving the prognosis in patients receiving thrombectomy for stroke with M1 or M1-M2 segment of the MCA occlusion.

CT Perfusion collateral index in assessment of collaterals in acute ischemic stroke with delayed presentation: Comparison to single phase CTA

BACKGROUND & PURPOSE

Perfusion collateral index (PCI) has been recently defined as a promising measure of collateral status. We sought to compare collateral status assessed via CT-PCI in comparison to single-phase CTA and their relationship to outcome measures including final infarction volume, final recanalization status and functional outcome in ELVO patients.

METHODS

ELVO patients with anterior circulation large vessel occlusion who had baseline CTA and CT perfusion and underwent endovascular treatment were included. Collateral status was assessed on CTA. PCI from CT perfusion was calculated in each patient and an optimal threshold to separate good vs insufficient collaterals was identified using DSA as reference. The collateral status determined by CTA and PCI were assessed against 3 measured outcomes: 1) final infarction volume; 2) final recanalization status defined by TICI scores; 3) functional outcome measured by 90-day mRS.

RESULTS

A total of 53 patients met inclusion criteria. Excellent recanalization defined by TICI ≥2C was achieved in 36 (68%) patients and 23 patients (43%) had good functional outcome (mRS ≤2). While having good collaterals on both CTA and CTP-PCI was associated with significantly (p<0.05) smaller final infarction volume, only good collaterals status determined by CTP-PCI was associated with achieving excellent recanalization (p = 0.001) and good functional outcome (p = 0.003).

CONCLUSION

CTP-based PCI outperforms CTA collateral scores in determination of excellent recanalization and good functional outcome and may be a promising imaging marker of collateral status in patients with delayed presentation of AIS.

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.

Time-resolved assessment of cortical venous drainage on multiphase CT angiography in patients with acute ischemic stroke

PURPOSE

Cortical vein opacification is not routinely assessed in patients presenting with acute ischemic stroke (AIS), and the value of temporal assessment of venous outflow is not known. We evaluated the utility of assessing cortical venous drainage over time using multiphase CT angiography (mCTA).

METHODS

Cortical venous drainage was assessed in patients from the Precise and Rapid Assessment of Collaterals Using Multi-Phase CTA in the Triage of Patients With Acute Ischemic Stroke for IA Therapy prospective multicenter cohort study of patients with symptoms of AIS with ICA and/or middle cerebral artery occlusion on baseline mCTA. Opacification of vein of Labbe, sphenoparietal sinus, superficial middle cerebral vein, and vein of Trolard of the affected hemisphere was graded as no (0), partial (1), or full (2) opacification in each mCTA phase. The venous opacification scores for each phase were added to generate a total venous score (TVS) (range 0-24). Primary outcome was 90-day modified Rankin score. Repeated measures analysis was used to assess the effect of phase timing on venous score on outcome.

RESULTS

Of 432 patients, 284 (65.7%) had proximal arterial occlusions. Median venous opacification score per phase (range 0-8) was 3 (IQR 1-6) in the first phase and increased in the second and third phases [median (IQR): 6 (5-8) and 8 (6-8), respectively] of the mCTA. In a multivariable analysis adjusting for age, baseline National Institutes of Health Stroke Scale, and Alberta stroke program early CT score, a significant association between TVS and 90-day mRS was noted ([adjusted cOR for TVS 6-11: 0.16 (95% CI 0.05-0.51); TVS 12-17: 0.18 (95% CI 0.06-0.57); TVS 18-24: 0.20 (0.06-0.63)]. Repeated measures analysis of venous scores from all three phases showed a significant effect of time/phase on TVS (p < 0.001).

CONCLUSION

This study concludes that venous opacification over time on multiphase CTA is associated with 90-day clinical outcome. There was however no added benefit of venous scoring vis-a-vis arterial collateral assessment in predicting outcome.

Role of modified TAN score in predicting prognosis in patients with acute ischemic stroke undergoing endovascular therapy

OBJECTIVE

The study aimed to evaluate the prognostic role of modified TAN collateral score in predicting functional independence in ischemic stroke patients, who underwent endovascular therapy.

INTRODUCTION

Identifying the group of patients, who will benefit most from arterial recanalization in patients with acute ischemic stroke, is the basis of success. Collateral circulation is a physiological condition that protects the brain against ischemia and inhibits the growth of a damaged area. The presence of collaterals is a well-known determinant for functional independence. Numerous collateral scoring systems are used for this purpose. The aim of this study was to evaluate the prognostic role of modified TAN collateral score (MTCS) in predicting functional independence in patients, who received endovascular therapy.

MATERIALS AND METHODS

Prospective data of 101 patients, who received endovascular therapy from the stroke team of Eskisehir Osmangazi University (ESOGÜ) between 2016 and 2017, were examined retrospectively for this purpose. Collateral assessments were performed in Computed Tomography Angiography (CTA) according to the modified TAN scoring system (< 50% refers to poor collateral status, ≥ 50% refers to good collateral status). Good clinical outcome was assessed as mRS 0-2 in the 3rd month. The TICI scoring system was used in the evaluation of recanalization. Patients treated within the first 6 h of symptom onset, patients with NCCT and contrast CTA, patients with internal carotid artery and middle cerebral artery occlusion were included in the study. Posterior system stroke was not included in the study.

CONCLUSION

Of the 101 patients, 50 (49%) had poor MTCS. Presentation and 24th hour NIHSS values of the patients with poor MTCS were higher (p:0.003). The third month mRS values were low in patients with good MTCS on admission, while these values were high in patients, who presented with poor MTCS. Mortality rates were significantly higher in the patient group with poor collateral circulation score (32-5.9%) (p:0.001). No significant differences were found in the presentation ASPECT values and (TICI 2b/3) recanalization rates of the patients. The rate of futile recanalization was significantly higher in the group with poor collateral circulation (52-8%) (p:0.0001). Presentation glucose, NIHSS, mTAN, symptom-puncture time, and good ASPECT score were found to be predictive markers for good outcome by univariate analysis. The major risk factors were determined by performing multiple logistic regression analysis. Presentation glucose, NIHSS, and mTAN (OR:1.013, 1.29, 0.198, respectively) were found to be strong and independent predictors for good clinical outcome. According to Multiple Binary Logistic Regression analysis Backward-ward model, Baseline NIHSS, poor collaterals and baseline glucose are found as predictors for poor outcome.

DISCUSSION

This study shows that good collateral score is associated with good clinical response, small final infarct volume, third month low mRS, low admission, and 24-hour NIHSS rates. The likelihood of having long term prognosis is 7 fold higher in patients with poor collaterals. The use of the MTCS system is recommended and supported due to its easy and rapid applicability.

Association of Plasma Metabolic Biomarker Sphingosine-1-Phosphate With Cerebral Collateral Circulation in Acute Ischemic Stroke

Background: The contribution of metabolic profile to the cerebral collateral circulation in acute ischemic stroke (AIS) has not been fully outlined. In this study, we conducted a metabolomic study to assess the relationship between the metabolic biomarkers and the collateral status of AIS.

Methods: A two-stage study was conducted from September 2019 to June 2021 in our hospital. There were 96 subjects including 66 patients with AIS and 30 healthy controls in the discovery stage and 80 subjects including 53 patients with AIS and 27 healthy controls in the validation stage. Collateral circulation was assessed by the Tan score based on computed tomographic angiography (CTA). Liquid chromatography-tandem mass spectrometry was used to identify differential metabolic markers. Then, an ELISA was employed to detect the plasma levels of sphingosine-1-phosphate (S1P).

Results:There were 114 differential metabolites between patients with AIS and control groups and 37 differential metabolites between good collateral circulation (GCC) and poor collateral circulation (PCC) groups. The pathway enrichment analysis revealed that arginine biosynthesis was the only statistically significant pathway between AIS and control groups and sphingolipid metabolism was the only statistically significant pathway between GCC and PCC groups. The differential metabolites sphinganine-1-phosphate (SA1P) and S1P belong to the sphingolipid metabolism. In the discovery stage, when the GCC group was compared with the PCC group, the receiver operating characteristic (ROC) analysis showed that plasma SA1P relative levels demonstrated an area under the curve (AUC) of 0.719 (95% CI: 0.582–0.834), and S1P levels demonstrated an AUC of 0.701 (95% CI: 0.567–0.819). In addition, both plasma SA1P and S1P relative levels showed significant negative correlations with the 90-day modified Rankin Scale (mRS) score. In the validation sample, higher plasma S1P levels were independent predictors of GCC (p = 0.014), and plasma S1P levels demonstrated an AUC of 0.738 (95% CI: 0.599–0.849) to differentiate patients with GCC from patients with PCC. In addition, plasma S1P levels also showed significant negative correlations with the 90-day mRS score.

Conclusion: We first illustrated the association between plasma metabolic profiles and cerebral collateral circulation in patients with AIS. Plasma S1P levels might be a potential diagnostic biomarker for predicting collateral circulation status in patients with AIS.

Hypoperfusion Intensity Ratio Correlates with CTA Collateral Status in Large-Vessel Occlusion Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Collateral blood supply is a key determinant of outcome in large-vessel occlusion acute ischemic stroke. Single- and multiphase CTA collateral scoring systems have been described but are subjective and require training. We aimed to test whether the CTP-derived hypoperfusion intensity ratio is associated with CTA collateral status and whether a threshold hypoperfusion intensity ratio exists that predicts poor CTA collaterals.

MATERIALS AND METHODS

Imaging and clinical data of consecutive patients with large-vessel occlusion acute ischemic stroke were retrospectively reviewed. Single-phase CTA and multiphase CTA scoring were performed by 2 blinded neuroradiologists using the Tan, Maas, and Calgary/Menon methods. CTP was processed using RApid processing of PerfusIon and Diffusion software (RAPID). Hypoperfusion intensity ratio = ratio of brain volume with time-to-maximum >10 seconds over time-to-maximum >6-second volume. Correlation between the hypoperfusion intensity ratio and CTA collateral scores was calculated using the Pearson correlation. The optimal threshold of the hypoperfusion intensity ratio for predicting poor collaterals was determined using receiver operating characteristic curve analysis.

RESULTS

Fifty-two patients with large-vessel occlusion acute ischemic stroke were included. Multiphase CTA collateral scoring showed better interrater agreement (κ = 0.813) than single-phase CTA (Tan, κ = 0.587; Maas, κ = 0.273). The hypoperfusion intensity ratio correlated with CTA collateral scores (multiphase CTA: r = -0.55; 95% CI, -0.67 to -0.40; P ≤ .001). The optimal threshold for predicting poor multiphase CTA collateral status was a hypoperfusion intensity ratio of >0.45 (sensitivity = 78%; specificity = 76%; area under the curve = 0.86). Patients with high hypoperfusion intensity ratio/poor collateral status had lower ASPECTS/larger infarcts, higher NIHSS scores, and larger hypoperfused volumes.

CONCLUSIONS

The hypoperfusion intensity ratio is associated with CTA collateral status in patients with large-vessel occlusion acute ischemic stroke. The hypoperfusion intensity ratio is an automated and quantitative alternative to CTA collateral scoring methods for both clinical and future stroke trial settings.

Acute Ischemic Stroke: MR Imaging-Based Paradigms

Multimodal MR imaging provides valuable information in the management of patients with acute ischemic stroke (AIS), with diagnostic, therapeutic, and prognostic implications. MR imaging plays a critical role in treatment decision making for (1) thrombolytic treatment of AIS patients with unknown symptom-onset and (2) endovascular treatment of patients with large vessel occlusion presenting beyond 6 hours from the symptom onset. MR imaging provides the most accurate information for detection of ischemic brain and is invaluable for differentiating AIS from stroke mimics.

Advances in imaging acute ischemic stroke: evaluation before thrombectomy

Recent advances in neuroimaging have demonstrated significant assessment benefits and appropriate triage of patients based on specific clinical and radiological features in the acute stroke setting. Endovascular thrombectomy is arguably the most important aspect of acute stroke management with an extended time window. Imaging-based physiological information may potentially shift the treatment paradigm from a rigid time-based model to a more flexible and individualized, tissue-based approach, increasing the proportion of patients amenable to treatment. Various imaging modalities are routinely used in the diagnosis and management of acute ischemic stroke, including multimodal computed tomography (CT) and magnetic resonance imaging (MRI). Therefore, these imaging methods should provide information beyond the presence or absence of intracranial hemorrhage as well as the presence and extent of the ischemic core, collateral circulation and penumbra in patients with neurological symptoms. Target mismatch may optimize selection of patients with late or unknown symptom onset who would potentially be eligible for revascularization therapy. The purpose of this study was to provide a comprehensive review of the current evidence about efficacy and theoretical basis of present imaging modalities, and explores future directions for imaging in the management of acute ischemic stroke.

Combining unsupervised and supervised learning for predicting the final stroke lesion

Predicting the final ischaemic stroke lesion provides crucial information regarding the volume of salvageable hypoperfused tissue, which helps physicians in the difficult decision-making process of treatment planning and intervention. Treatment selection is influenced by clinical diagnosis, which requires delineating the stroke lesion, as well as characterising cerebral blood flow dynamics using neuroimaging acquisitions. Nonetheless, predicting the final stroke lesion is an intricate task, due to the variability in lesion size, shape, location and the underlying cerebral haemodynamic processes that occur after the ischaemic stroke takes place. Moreover, since elapsed time between stroke and treatment is related to the loss of brain tissue, assessing and predicting the final stroke lesion needs to be performed in a short period of time, which makes the task even more complex. Therefore, there is a need for automatic methods that predict the final stroke lesion and support physicians in the treatment decision process. We propose a fully automatic deep learning method based on unsupervised and supervised learning to predict the final stroke lesion after 90 days. Our aim is to predict the final stroke lesion location and extent, taking into account the underlying cerebral blood flow dynamics that can influence the prediction. To achieve this, we propose a two-branch Restricted Boltzmann Machine, which provides specialized data-driven features from different sets of standard parametric Magnetic Resonance Imaging maps. These data-driven feature maps are then combined with the parametric Magnetic Resonance Imaging maps, and fed to a Convolutional and Recurrent Neural Network architecture. We evaluated our proposal on the publicly available ISLES 2017 testing dataset, reaching a Dice score of 0.38, Hausdorff Distance of 29.21 mm, and Average Symmetric Surface Distance of 5.52 mm.

Automated Perfusion Calculations vs. Visual Scoring of Collaterals and CBV-ASPECTS : Has the Machine Surpassed the Eye?

Purpose

Use of automated perfusion software has gained importance for imaging of stroke patients for mechanical thrombectomy (MT). We aim to compare four perfusion software packages: 1) with respect to their association with 3‑month functional outcome after successful reperfusion with MT in comparison to visual Cerebral Blood Volume - Alberta Stroke Program Early CT Score (CBV-ASPECTS) and collateral scoring and 2) with respect to their agreement in estimation of core and penumbra volume.

Methods

This retrospective, multicenter cohort study (2015–2019) analyzed data from 8 centers. We included patients who were functionally independent before and underwent successful MT of the middle cerebral artery. Primary outcome measurements were the relationship of core and penumbra volume calculated by each software, qualitative assessment of collaterals and CBV-APECTS with 3‑month functional outcome and disability (modified Rankin scale >2). Quantitative differences between perfusion software measurements were also assessed.

Results

A total of 215 patients (57% women, median age 77 years) from 8 centers fulfilled the inclusion criteria. Multivariable analyses showed a significant association of RAPID core (common odds ratio, cOR 1.02; p = 0.015), CBV-ASPECTS (cOR 0.78; p = 0.007) and collaterals (cOR 0.78; p = 0.001) with 3‑month functional outcome (shift analysis), while RAPID core (OR 1.02; p = 0.018), CBV-ASPECTS (OR 0.77; p = 0.024), collaterals (OR 0.78; p = 0.007) and OLEA core (OR 1.02; p = 0.029) were significantly associated with 3‑month functional disability. Mean differences on core estimates between VEOcore and RAPID were 13.4 ml, between syngo.via and RAPID 30.0 ml and between OLEA and RAPID −3.2 ml.

Conclusion

Collateral scoring, CBV-ASPECTS and RAPID were independently associated with functional outcome at 90 days. Core and Penumbra estimates using automated software packages varied significantly and should therefore be used with caution.

Electronic supplementary material

The online version of this article (10.1007/s00062-020-00974-3) contains supplementary material, which is available to authorized users.

Effect of Recanalization on Cerebral Edema, Long-Term Outcome, and Quality of Life in Patients with Large Hemispheric Infarctions

OBJECTIVES

Space-occupying cerebral edema is the main cause of mortality and poor functional outcome in patients with large cerebral artery occlusion (LVO). We aimed to determine whether recanalization of LVO would augment cerebral edema volume and the impact on functional outcome and quality of life (QoL).

MATERIALS AND METHODS

Prospectively, 43 patients with large middle cerebral artery territory infarction or NIHSS ≥ 12 on admission were enrolled. The degree of recanalization (partial and complete versus no recanalization) was assessed by computed tomography (CT)-angiography or Duplex ultrasound more than 24 h after symptom onset. Cerebral edema volume was measured on follow up CTs by computer-based planimetry. Mortality, functional outcome (by modified Ranking Scale (mRS) and Barthel Index (BI)) were assessed at discharge and 12 months, and QoL (by SF-36 and EQ-5D-3L) at 12 months.

RESULTS

Mean cerebral edema volume was 333±141 ml without recanalization (n=13, group 1) and 276±140 ml with partial or complete recanalization (n=30, group 2, p= 0.23). There were no significant differences in mortality at discharge (38% versus 23%), at 12 months (58% versus 48%), in functional outcome at discharge (mRS 0-3: 0% both; mRS 4-5: 62% versus 77%) and at 12 months (mRS 0-3: 0% versus 11%; mRS 4-5: 42% versus 41%). The BI improved significantly from discharge to 12 months only in group 2 (p=0.001). Mean physical component score in SF-36 was 25.6±6.4, psychological component score was 41.9±14.1. In the EQ-5D-3L, most patients reported problems with activities of daily living, reduced mobility, and selfcare.

CONCLUSIONS

Recanalization of a large cerebral artery occlusion in the anterior circulation territories is not associated with amplification of post-ischemic cerebral edema but may be correlated with better long-term functional outcome. QoL was low and mainly dependent on physical disability. The association between recanalization, collateral status and development of cerebral edema after LVO and the effect on functional outcome and quality of life should be explored in a larger patient population.

Cerebral collaterals in acute ischaemia: Implications for acute ischaemic stroke patients receiving reperfusion therapy

The cerebral collaterals play an important role in penumbral tissue sustenance after an acute ischaemic stroke. Recent studies have demonstrated the potential role of collaterals in the selection of acute ischaemic stroke patients eligible for reperfusion therapy. However, the understanding of the significance and evidence around the role of collateral status in predicting outcomes in acute ischaemic stroke patients treated with reperfusion therapy is still unclear. Moreover, the use of pre-treatment collaterals in patient selection and prognosis is relatively underappreciated in clinical settings. A focused review of the literature was performed on the various methods of collateral evaluation and the role of collateral status in acute ischaemic stroke patients receiving reperfusion therapy. We discuss the methods of evaluating pre-treatment collaterals in clinical settings. The patient selection based on collateral status as well as the prognostic and therapeutic value of collaterals in acute ischaemic stroke, in settings of intravenous thrombolysis or endovascular therapy alone, and bridge therapy, are summarized. Recommendations for future research and possible pharmacological intervention strategies aimed at collateral enhancement are also discussed. Collaterals may play an important role in identifying acute ischaemic stroke patients who are likely to benefit from endovascular treatment in an extended time window. Future neuroscientific efforts to better improve our understanding of the role of collaterals in acute ischaemia as well as clinical studies to delineate its role in patient selection and acute stroke prognosis are warranted.

Atrial Fibrillation Treatment Adequacy and Outcome after Endovascular Thrombectomy

BACKGROUND

Atrial fibrillation (AF) often leads to large vessel occlusions (LVO) which may necessitate endovascular thrombectomy (EVT). Whether the adequacy of treatment with oral anticoagulants (OAC) prior to LVO modifies outcomes remains unknown.

PATIENTS AND METHODS

Consecutive EVT-treated LVO patients were recruited and the data was analyzed retrospectively. We combined patients with known AF that were untreated with OAC or inadequately treated with those with new-onset AF to form a group of undertreated-AF patients and compared them to adequately treated AF patients.

RESULTS

Of the 230 patients included, 109 (47%) had AF (86 known AF, 23 new-onset AF). AF patients were significantly older and more often reached favorable recanalization but less often had favorable outcomes compared to those without AF. Most patients with known AF (76%) were inadequately treated at stroke onset. Patients with undertreated-AF more often received tPA prior to EVT (26% vs. 4% p=0.009), more often had favorable collaterals (65% vs. 33% p<0.001) and more often reached favorable outcomes (28% vs. 9%, p=0.047) compared to adequately treated AF patients. On multivariate analyses adequately treated AF did not impact survival (Odds Ration [OR] 0.89 95% Confidence Interval [CI] 0.23-3.43), chances for favorable recanalization (OR 0.57 95%CI 0.15-2.13) or favorable outcome (OR 5.95 95%CI 0.62-57.39).

CONCLUSIONS

Treatment adequacy does not affect the rates of favorable functional outcome or survival in AF patients with LVO.

Contemporary Management of Acute Ischemic Stroke Across the Continuum: From TeleStroke to Intra-Arterial Management

In this comprehensive contemporary review of acute ischemic stroke management, what is new and different will be highlighted beginning with prehospital stroke systems of care, emergency medical systems, and mobile stroke units, followed by hospital stroke teams, emergency evaluation, telemedicine, and brain and vascular imaging, and finishing with emergency treatments including thrombolysis and mechanical thrombectomy.

Single-phase computed tomography angiography sufficiently predicts outcomes after mechanical thrombectomy

BACKGROUND

Arterial collateral (AC) assessed by single-phase computed tomography angiography (CTA) or multiphase CTA has been used to predict clinical outcomes in patients undergoing mechanical thrombectomy (MT). Recently, venous opacification (VO) was proposed as another accurate image marker. This study aimed to compare the efficacy using AC and VO as predictors of MT outcome.

METHODS

Patients with occlusion of the proximal anterior circulation undergoing MT were included retrospectively. We assessed the AC status respectively according to different methods: modified Tan score, Miteff score in single-phase CTA, and pial arterial filling score in multiphase CTA. VO was assessed according to cortical vein opacification score. Favorable clinical outcome was defined as modified Rankin Scale 0-2 90 days after MT. Logistic regression models were established and receiver operating characteristics curve were used to determine the predictability of favorable outcome in patients with adequate AC and VO.

RESULTS

A total of 75 patients were enrolled. Adequate AC identified by modified Tan score (odds ratio, 7.3; p < 0.001), Miteff score (odds ratio, 4.5; p = 0.009), significantly predicted favorable outcome, but not adequate VO. The area under the curve was largest for adequate AC in model of modified Tan score 0.730 (95% CI, 0.60-0.86), while adequate VO showed the least area under the curve: 0.577 (95% CI, 0.43-0.73).

CONCLUSION

We considered adequate AC in single-phase CTA could be reliable enough as an imaging marker rather than adequate VO to predict favorable outcome after MT.

The Continued Role and Value of Imaging for Acute Ischemic Stroke

Advances in neuroimaging in the last 2 decades have revolutionized the management of acute ischemic stroke (AIS). Here we review the development of computed tomography (CT) and magnetic resonance imaging (MRI) modalities used to guide treatment of patients with AIS characterized by large vessel occlusion. In particular, we highlight recent randomized trials and their patient selection methodologies to detail the progression of these selection paradigms. With advanced imaging, distinction between at-risk penumbra and ischemic core in AIS may be performed using either CT or MRI. While limitations exist for methodologies to quantify core and penumbra, commercially available fully automated software packages provide useful information to guide treatment decisions. Randomized controlled trials implementing perfusion imaging to patient selection algorithms have demonstrated marked success in improving functional outcomes in patients with large vessel occlusions. As such, imaging has become a vital aspect of AIS treatment in selecting patients who may benefit from mechanical thrombectomy.

Collateral Recruitment Is Impaired by Cerebral Small Vessel Disease

Background and Purpose- Cerebral small vessel disease (SVD) is associated with increased stroke risk and poor stroke outcomes. We aimed to evaluate whether chronic SVD burden is associated with poor recruitment of collaterals in large-vessel occlusive stroke. Methods- Consecutive patients with middle cerebral artery or internal carotid artery occlusion presenting within 6 hours after stroke symptom onset who underwent thrombectomy from 2012 to 2017 were included. The prespecified primary outcome was poor collateral flow, which was assessed on baseline computed tomographic angiography (poor, ≤50% filling; good, >50% filling). Markers of chronic SVD on brain magnetic resonance imaging were rated for the extent of white matter hyperintensities, enlarged perivascular spaces, chronic lacunar infarctions and cerebral microbleeds using the Standards for Reporting Vascular Changes on Neuroimaging criteria. Severity of SVD was quantified by adding the presence of each SVD feature, with a total possible score of 0 to 4; each SVD type was also evaluated separately. Multivariable logistic regression analyses were performed to evaluate the relationships between SVD and poor collaterals, with adjustment for potential confounders. Results- Of the 100 eligible patients, the mean age was 65±16 years, median National Institutes of Health Stroke Scale score was 15, and 68% had any SVD. Poor collaterals were observed in 46%, and those with SVD were more likely to have poor collaterals than patients without SVD (aOR, 1.9 [95% CI, 1.1-3.2]). Of the SVD types, poor collaterals were significantly associated with white matter hyperintensities (aOR, 2.9 per Fazekas increment [95% CI, 1.6-5.3]) but not with enlarged perivascular spaces (adjusted odds ratio [aOR], 1.3 [95% CI, 0.4-4.0]), lacunae (aOR, 2.1 [95% CI, 0.6-7.1]), or cerebral microbleeds (aOR, 2.1 [95% CI, 0.6-7.8]). Having a greater number of different SVD markers was associated with a higher odds of poor collaterals (crude trend P<0.001; adjusted P=0.056). There was a dose-dependent relationship between white matter hyperintensity burden and poor collaterals: adjusted odds of poor collaterals were 1.5, 3.0, and 9.7 across Fazekas scores of 1 to 3 (Ptrend=0.015). No patient with an SVD score of 4 had good collaterals. Conclusions- Chronic cerebral SVD is associated with poor recruitment of collaterals in large vessel occlusive stroke. A prospective study to elucidate the potential mechanism of how SVD may impair the recruitment of collaterals is ongoing.

Prediction contribution of the cranial collateral circulation to the clinical and radiological outcome of ischemic stroke

BACKGROUND AND AIM

The extent of penumbra tissue and outcome in stroke patients depend on the collateral cranial vasculature. To provide optimal individualized care for stroke patients in the emergency room setting we investigated the predictive capability of a stringent evaluation of the collateral vessels in ischemic stroke on clinical outcome and infarct size.

METHODS

We retrospectively studied uniform clinical and radiological data of 686 consecutive patients admitted to the emergency department with suspected acute ischemic stroke. Cranial collateral vasculature status was graded using the initial CT-angiography. Outcome was measured by mRS, NIHSS and final infarct size at hospital discharge. All data were used to build a linear regression model to predict the patients´ outcome.

RESULTS

Univariate and multivariate analyses showed significant effects of the whole brain collateral vessel score on all outcome variables. Atherosclerosis and piale collateral status were associated with the final infarct volume (FIV). Atherosclerosis and age were associated with the NIHSS at discharge. The presence of atherosclerosis, glucose level on admission and age were associated with the mRS at discharge. The multivariate models were able to predict 29% of the variance of the mRS at discharge, 24% of the variance in FIV and 17% of the variance of the NIHSS at discharge. The whole brain collateral status and the presence of atherosclerosis were the most relevant predictors for the clinical and radiological outcome.

CONCLUSION

The whole brain collateral vasculature status is clearly associated with clinical and radiological outcome but in a multivariate model seems not sufficiently predictive for FIV, mRS and NIHSS outcome at discharge in non-preselected patients admitted to the emergency department with ischemic stroke.

Multiphase MR Angiography Collateral Map: Functional Outcome after Acute Anterior Circulation Ischemic Stroke

Background Collateral circulation determines tissue fate and affects treatment result in acute ischemic stroke. A precise method for collateral estimation in an optimal imaging protocol is necessary to make an appropriate treatment decision for acute ischemic stroke. Purpose To verify the value of multiphase collateral imaging data sets (MR angiography collateral map) derived from dynamic contrast material-enhanced MR angiography for predicting functional outcomes after acute ischemic stroke. Materials and Methods This secondary analysis of an ongoing prospective observational study included data from participants with acute ischemic stroke due to occlusion or stenosis of the unilateral internal carotid artery and/or M1 segment of the middle cerebral artery who were evaluated within 8 hours of symptom onset. Data were obtained from March 2016 through August 2018. The collateral grading based on the MR angiography collateral map was estimated by using six-scale MR acute ischemic stroke collateral (MAC) scores. To identify independent predictors of favorable functional outcomes, age, sex, risk factors, baseline National Institutes of Health Stroke Scale (NIHSS) score, baseline diffusion-weighted imaging (DWI) lesion volume, site of steno-occlusion, collateral grade, mode of treatment, and early reperfusion were evaluated with multiple logistic regression analyses. Results One hundred fifty-four participants (mean age ± standard deviation, 69 years ± 13; 99 men) were evaluated. Younger age (odds ratio [OR], 0.45; 95% confidence interval [CI]: 0.29, 0.70; P < .001), lower baseline NIHSS score (OR, 0.85; 95% CI: 0.78, 0.94; P < .001), MAC score of 3 (OR, 27; 95% CI: 4.0, 179; P < .001), MAC score of 4 (OR, 17; 95% CI: 2.1, 134; P = .007), MAC score of 5 (OR, 27; 95% CI: 2.5, 306; P = .007), and successful early reperfusion (OR, 7.5; 95% CI: 2.6, 22; P < .001) were independently associated with favorable functional outcomes in multivariable analysis. There was a linear negative association between collateral perfusion grades and functional outcomes (P < .001). Conclusion An MR angiography collateral map was clinically reliable for collateral estimation in patients with acute ischemic stroke. This map provided patient-specific pacing information for ischemic progression. © RSNA, 2020.

Multiphase adjuvant neuroprotection: A novel paradigm for improving acute ischemic stroke outcomes

While several large pivotal clinical trials recently revealed a substantial benefit of endovascular thrombectomy for acute ischemic stroke (AIS) caused by large-vessel occlusion, many patients still experience mediocre prognosis. Enlargement of the ischemic core, failed revascularization, incomplete reperfusion, distal embolization, and secondary reperfusion injury substantially impact the salvaging of brain tissue and the functional outcomes of AIS. Here, we propose novel concept of “Multiphase Adjuvant Neuroprotection” as a new paradigm that may help guide our search for adjunctive treatments to be used together with thrombectomy. The premise of multiphase adjuvant neuroprotection is based on the diverse and potentially nonoverlapping pathophysiologic mechanisms that are triggered before, during, and after thrombectomy therapies. Before thrombectomy, strategies should focus on preventing the growth of the ischemic core; during thrombectomy, improving recanalization while reducing distal embolization and maximizing reperfusion are of significant importance; after reperfusion, strategies should focus on seeking targets to reduce secondary reperfusion injury. The concept of multiphase adjuvant neuroprotection, wherein different strategies are employed throughout the various phases of clinical care, might provide a paradigm to minimize the final infarct size and improve functional outcome in AIS patients treated with thrombectomy. With the success of thrombectomy in selected AIS patients, there is now an opportunity to revisit stroke neuroprotection. Notably, if the underlying mechanisms of these neuroprotective strategies are identified, their role in the distinct phases will provide further avenues to improve patient outcomes of AIS.

From "Time is Brain" to "Imaging is Brain": A Paradigm Shift in the Management of Acute Ischemic Stroke

Arterial recanalization to restore the blood supply and limit the brain damage is the primary goal in the management of acute ischemic stroke (AIS). Since the publication of pivotal randomized clinical trials in 2015, endovascular thrombectomy has become part of the standard of care in selected cases of AIS from large-vessel occlusions up to 6 hours after the onset of symptoms. However, the association between endovascular reperfusion and improved functional outcome is not strictly time dependent. Rather than on rigid time windows, candidates should be selected based on vascular and physiologic information. This approach places imaging data at the center of treatment decisions. Advances in imaging-based management of AIS provide crucial information about vessel occlusion, infarct core, ischemic penumbra, and degree of collaterals. This information is invaluable in identifying patients who are likely to benefit from reperfusion therapies and excluding those who are unlikely to benefit or are at risk of adverse effects. The approach to reperfusion therapies continues to evolve, and imaging is acquiring a greater role in the diagnostic work-up and treatment decisions as shown in recent clinical trials with extended time window. The 2018 American Heart Association/American Stroke Association guidelines reflect a paradigm shift in the management of AIS from "Time is Brain" to "Imaging is Brain." This review discusses the essential role of multimodal imaging developing from recent trials on therapy for AIS.

Triiodothyronine levels were positively correlated with opening of collateral circulation in cerebral infarction patients with large artery atherosclerosis

INTRODUCTION

Non-thyroidal illness syndrome (NTIS) is one of the signs for poor prognosis of cerebral infarction (CI), but its risk factors had never been explored. In this study, we analyzed the potential effect of collateral circulation on prognosis prediction of triiodothyronine for large artery atherosclerosis cerebral infarction (LAA-CI) patients.

MATERIAL AND METHODS

Clinical data of CI patients between 2012 and 2014 were collected. Imaging inspection was used for determining TOAST classification and evaluating collateral circulation. One-year follow-up was conducted for mRS score by telephone.

RESULTS

T3 level in the NTIS group (p = 0.001) was significantly decreased while TSH level (p < 0.001) was increased. Patients in the NTIS group had a poorer prognosis (p = 0.008) and the main reason was the high mortality (p = 0.002). NTIS predicted poor collateral circulation (p = 0.026) and good collateral circulation tended to be less likely concomitant with NTIS (p = 0.001). Logistic regression analysis showed that triiodothyronine concentrations (OR = 4.760, 95% CI: 1.981-11.456, p < 0.001) were positively correlated with but advanced age (OR = 0.756, 95% CI: 0.645-0.886, p = 0.001) negatively with opening of collateral circulation.

CONCLUSIONS

Poor opening of collateral circulation was likely to mediate the prediction of NTIS for prognosis of LAA-CI patients.

Results From DEFUSE 3: Good Collaterals Are Associated With Reduced Ischemic Core Growth but Not Neurologic Outcome

Background and Purpose- The effect of leptomeningeal collaterals for acute ischemic stroke patients with large vessel occlusion in the late window (>6 hours from last known normal) remains unknown. We sought to determine if collateral status on baseline computed tomography angiography impacted neurological outcome, ischemic core growth, and moderated the effect of endovascular thrombectomy in the late window. Methods- This is a prespecified analysis of DEFUSE 3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke). We included patients with computed tomography angiography as their baseline imaging and rated collateral status using the validated scales described by Tan and Maas. The primary outcome is functional independence (modified Rankin Scale score of ≤2). Additional outcomes include the full range of the modified Rankin Scale, baseline ischemic core volume, change from baseline in the ischemic core volume at 24 hours, and death at 90 days. Results- Of the 130 patients in our cohort, 33 (25%) had poor collaterals and 97 (75%) had good collaterals. There was no difference in the rate of functional independence with good versus poor collaterals in unadjusted analysis (30% versus 39%; P=0.3) or after adjustment for treatment arm (odds ratio [95% CI], 0.61 [0.26-1.45]). Good collaterals were associated with significantly smaller ischemic core volume and less ischemic core growth. The difference in the treatment effect of endovascular thrombectomy was not significant ( P=0.8). Collateral status also did not affect the rate of stroke-related death (n [%], good versus poor collaterals, 18/97 [19%] versus 8/33 [24%], P=0.5]. Conclusions- In DEFUSE 3 patients, good leptomeningeal collaterals on single phase computed tomography angiography were not predictive of functional independence or death and did not impact the treatment effect of endovascular thrombectomy. These unexpected findings require further study to confirm their validity and to better understand the role of collaterals for stroke patients with anterior circulation large vessel occlusion in the late therapeutic window. Clinical Trial Registration- URL: https://www.clinicaltrials.gov . Unique identifier: NCT02586415.

Guidelines for the Early Management of Patients With Acute Ischemic Stroke: 2019 Update to the 2018 Guidelines for the Early Management of Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

Background and Purpose- The purpose of these guidelines is to provide an up-to-date comprehensive set of recommendations in a single document for clinicians caring for adult patients with acute arterial ischemic stroke. The intended audiences are prehospital care providers, physicians, allied health professionals, and hospital administrators. These guidelines supersede the 2013 Acute Ischemic Stroke (AIS) Guidelines and are an update of the 2018 AIS Guidelines. Methods- Members of the writing group were appointed by the American Heart Association (AHA) Stroke Council's Scientific Statements Oversight Committee, representing various areas of medical expertise. Members were not allowed to participate in discussions or to vote on topics relevant to their relations with industry. An update of the 2013 AIS Guidelines was originally published in January 2018. This guideline was approved by the AHA Science Advisory and Coordinating Committee and the AHA Executive Committee. In April 2018, a revision to these guidelines, deleting some recommendations, was published online by the AHA. The writing group was asked review the original document and revise if appropriate. In June 2018, the writing group submitted a document with minor changes and with inclusion of important newly published randomized controlled trials with >100 participants and clinical outcomes at least 90 days after AIS. The document was sent to 14 peer reviewers. The writing group evaluated the peer reviewers' comments and revised when appropriate. The current final document was approved by all members of the writing group except when relationships with industry precluded members from voting and by the governing bodies of the AHA. These guidelines use the American College of Cardiology/AHA 2015 Class of Recommendations and Level of Evidence and the new AHA guidelines format. Results- These guidelines detail prehospital care, urgent and emergency evaluation and treatment with intravenous and intra-arterial therapies, and in-hospital management, including secondary prevention measures that are appropriately instituted within the first 2 weeks. The guidelines support the overarching concept of stroke systems of care in both the prehospital and hospital settings. Conclusions- These guidelines provide general recommendations based on the currently available evidence to guide clinicians caring for adult patients with acute arterial ischemic stroke. In many instances, however, only limited data exist demonstrating the urgent need for continued research on treatment of acute ischemic stroke.

Collateral Clock Is More Important Than Time Clock for Tissue Fate

Background and Purpose- Although perfusion abnormality is an increasingly important therapeutic target, the natural history of tissue at risk without reperfusion treatment is understudied. Our objective was to determine how time affects penumbral salvage and infarct growth in untreated acute ischemic stroke patients and whether collateral status affects this relationship. Methods- We used a prospectively collected, multicenter acute stroke registry to assess acute stroke patients who were not treated with intravenous thrombolysis or endovascular treatment. We analyzed baseline computed tomography angiogram and computed tomography perfusion within 24 hours of stroke onset along with follow-up imaging and assessed time from stroke onset to baseline imaging, ASPECTS (Alberta Stroke Program Early CT Score), vessel occlusion, collaterals, ischemic core, and penumbra. Penumbral salvage and infarct growth were calculated. Correlations between time and penumbral salvage and infarct growth were evaluated with Spearman correlation. Penumbral salvage and infarct growth were compared between subjects with good versus poor collateral status using the Wilcoxon rank-sum test. Clinical and imaging factors affecting penumbral salvage and infarct growth were evaluated by linear regression. Results- Among 94 untreated stroke patients eligible for this analysis, the mean age was 65 years, median National Institutes of Health Stroke Scale score was 13, and median (range) time from stroke onset to baseline imaging was 2.9 (0.4-23) hours. There was no correlation between time and salvaged penumbra ( r=0.06; P=0.56) or infarct growth ( r=-0.05; P=0.61). Infarct growth was higher among those with poor collaterals versus those with good collaterals (median, 52.3 versus 0.9 cm³; P<0.01). Penumbral salvage was lower among those with poor collaterals compared with those with good collaterals (poor, 0 [0-0]; good, 5.9 cm³ [0-29.4]; P<0.01). Multivariable linear regression demonstrated that collaterals, but not time, were significantly associated with infarct growth and penumbral salvage. Conclusions- In this natural history study, penumbral salvage and infarct growth were less time dependent and more a measure of collateral flow.

Dichotomizing Level of Pial Collaterals on Multiphase CT Angiography for Endovascular Treatment in Acute Ischemic Stroke: Should It Be Refined for 6-Hour Time Window?

Purpose

Although endovascular treatment is currently thought to only be suitable for patients who have pial arterial filling scores >3 as determined by multiphase computed tomography angiography (mpCTA), a cut-off score of 3 was determined by a study, including patients within 12 hours after symptom onset. We aimed to investigate whether a cut-off score of 3 for endovascular treatment within 6 hours of symptom onset is an appropriate predictor of good functional outcome at 3 months.

Materials and Methods

From April 2015 to January 2016, acute ischemic stroke patients treated with mechanical thrombectomy within 6 hours of symptom onset were enrolled into this study. Pial arterial filling scores were semi-quantitatively assessed using mpCTA, and clinical and radiological parameters were compared between patients with favorable and unfavorable outcomes. Multivariate logistic regression analysis was then performed to investigate the independent association between clinical outcome and pial collateral score, with the predictive power of the latter assessed using C-statistics.

Results

Of the 38 patients enrolled, 20 (52.6%) had a favorable outcome and 18 had an unfavorable outcome, with the latter group showing a lower mean pial arterial filling score (3.6±0.8 vs. 2.4±1.2, P=0.002). After adjusting for variables with a P-value of <0.1 in univariate analysis (i.e., age and National Institutes of Health Stroke Scale score at admission), pial arterial filling scores higher than a cut-off of 2 were found to be independently associated with favorable clinical outcomes (P=0.012). C-statistic analysis confirmed that our model had the highest prediction power when pial arterial filling scores were dichotomized at >2 vs. ≤2.

Conclusion

A pial arterial filling cut-off score of 2 as determined by mpCTA appears to be more suitable for predicting clinical outcomes following endovascular treatment within 6 hours of symptom onset than the cut-off of 3 that had been previously suggested.