Systematic evaluation of computed tomography angiography collateral scores for estimation of long-term outcome after mechanical thrombectomy in acute ischaemic stroke

Predictors of futile recanalization after endovascular treatment of acute ischemic stroke

OBJECTIVE

Endovascular therapy (EVT) is the most successful treatment for patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO) in the anterior circulation. However, futile recanalization (FR) seriously affects the prognosis of these patients. The aim of this study was to investigate predictors of FR after EVT in patients with AIS.

METHOD

Patients diagnosed with AIS due to anterior circulation LVO and receiving EVT between June 2020 and October 2022 were prospectively enrolled. FR after EVT was defined as a poor 90-day prognosis (modified Rankin Scale [mRS] score ≥ 3) despite achieving successful reperfusion (modified Thrombolysis in Cerebral Infarction [mTICI] classification of 2b-3). All included patients were categorized into control group (mRS score < 3) and FR group (mRS score ≥ 3). Demographic characteristics, comorbidities (hypertension, diabetes, atrial fibrillation, smoking, etc.), stroke-specific data (NIHSS score, ASPECT score and site of occlusion), procedure data (treatment type [direct thrombectomy vs. bridging thrombectomy], degree of vascular recanalization [mTICI], procedure duration time and onset-recanalization time), laboratory indicators (lymphocytes count, neutrophils count, monocytes count, C-reactive protein, neutrophil-to-lymphocyte ratio [NLR], monocyte-to-high-density lipoprotein ratio [MHR], lymphocyte-to-monocyte ratio [LMR], lymphocyte-to-C-reactive protein ratio [LCR], lymphocyte-to-high-density lipoprotein ratio[LHR], total cholesterol and triglycerides.) were compared between the two groups. Multivariate logistic regression analysis was performed to explore independent predictors of FR after EVT.

RESULTS

A total of 196 patients were included in this study, among which 57 patients were included in the control group and 139 patients were included in the FR group. Age, proportion of patients with hypertension and diabetes mellitus, median NIHSS score, CRP level, procedure duration time, neutrophil count and NLR were higher in the FR group than in the control group. Lymphocyte count, LMR, and LCR were lower in the FR group than in the control group. There were no significant differences in platelet count, monocytes count, total cholesterol, triglycerides, HDL, LDL, gender, smoking, atrial fibrillation, percentage of occluded sites, onset-recanalization time, ASPECT score and type of treatment between the two groups. Multivariate logistic regression analysis demonstrated that NLR was independently associated with FR after EVT (OR = 1.37, 95%CI = 1.005-1.86, P = 0.046).

CONCLUSION

This study demonstrated that high NLR was associated with a risk of FR in patients with AIS due to anterior circulation LVO. These findings may help clinicians determine which patients with AIS are at higher risk of FR after EVT. Our study can provide a theoretical basis for interventions in the aforementioned population.

Evaluation of the relationship between computed tomography angiography collateral scores and clinical outcome

BACKGROUND

 The relationship between collateral circulation and prognosis after endovascular treatment in anterior circulation strokes has been reported in many studies.

OBJECTIVE

 In this study, we aimed to compare the predictive power of clinical outcome by comparing five different collateral scores that are frequently used.

METHODS

 Among the patients who underwent endovascular treatment in our clinic between November 2019 and December 2021, patients with premorbid mRS < 3, intracranial ICA and/or MCA M1 occlusion, and a pre-procedural multiphase CTA examination were included in the study. Demographic, technical, and duration information about the procedure, major events after the procedure, and clinical outcomes at 3 months were recorded. The mCTA, Tan, Maas, Miteff, and rLMC collateral scores of the patients were evaluated.

RESULTS

 Clinical outcome at 3 months were good in 37 of the 68 patients included in the study (mRS ≤ 2). Only the mCTA and rLMC collateral scores were statistically significantly higher in those with a good clinical outcome. Significant correlation with 3-month mRS was detected only in mCTA and rLMC scores. Although rLMC and mCTA collateral scores showed a statistically significant association with prognosis, they were not sufficient to be an independent predictor of prognosis.

CONCLUSION

 mCTA and rLMC were found to have the highest predictive power of clinical outcome and the highest correlation with the 3-month clinical outcome. Our study suggests that it would be beneficial to develop a new scoring system over multiphase CTA, which combines regional and temporal evaluation, which are the strengths of both collateral scoring.

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.

The Presence of Communicating Arteries in the Circle of Willis Is Associated with Higher Rate of Functional Recovery after Anterior Circulation Ischemic Stroke

Acute ischemic stroke (AIS) is the world's second leading cause of mortality. An established method for treating stroke patients in acute settings is endovascular therapy (EVT). However, the correlation of the successful endovascular treatment of AIS with the presence of communicating arteries in the circle of Willis needs to be proven. Our study examined clinical and radiological data of 158 consecutive patients treated with mechanical thrombectomy (MT) at our comprehensive stroke center. We analyzed their CT angiograms and digital subtraction angiography (DSA) to assess anatomical variants of Willis' circle and formed two groups-collateral-negative and collateral-positive group. The first group included patients with aplasia of both anterior (ACoA) and posterior communicating Artery (PCoA). The second group included patients that have at least one communicating artery (either anterior or posterior). We evaluated their reperfusion outcomes and functional recovery three months later. Our results showed that patients with communicating arteries had smaller areas of infarction on post-interventional CT and higher rates of functional recovery (Modified Rankin Score). The ACoA had a higher impact on early and late outcomes, confirmed by lower control CT scores and more favorable functional recovery. Therefore, anatomic variants of Willis' circle should be considered as a significant prognostic factor in AIS.

Association between left atrial enlargement and poor cerebral collaterals in large vessel occlusion

OBJECTIVES

Left atrial enlargement (LAE) is a known risk factor for atrial fibrillation, a common cause of large vessel occlusion (LVO) leading to ischemic stroke. While robust cerebral collaterals protect penumbral tissue from infarction, the effect of structural heart disease on cerebral collaterals remains uncertain. This study aims to investigate the association between LAE and cerebral collaterals in patients with acute LVO stroke.

MATERIALS AND METHODS

We conducted a retrospective study of consecutive patients with middle cerebral and/or internal carotid LVO who underwent endovascular thrombectomy (EVT) between 2012 to 2020. Consecutive patients with echocardiography and computed tomography angiography (CTA) of the head were included. Multivariate logistic regression analysis was performed to evaluate the relationship between LAE and poor cerebral collaterals, adjusting for demographics (age, sex, race) and vascular risk factors (hypertension, diabetes and smoking).

RESULTS

The study included 235 patients with mean age of 69±15 years and an initial mean National Institutes of Health Stroke Scale score of 18. Of these, 89 (37.9 %) had LAE, and 105 (44.7 %) had poor collaterals. Patients with LAE were more likely to have poor collaterals compared to those without LAE (58.4 % vs 36.3 %, P = 0.001). LAE was independently associated with higher odds of poor collaterals (odds ratio, 2.47; P = 0.001), even after adjusting for covariables (odds ratio 1.84, P = 0.048).

CONCLUSIONS

Our study demonstrated a significant association between LAE and poor cerebral collaterals in patients with LVO stroke undergoing EVT. Further research is warranted to explore potential shared mechanisms, such as endothelial dysfunction, underlying this heart-brain association.

Inter-Rater Reliability of Collateral Status Assessment Based on CT Angiography: A Retrospective Study of Middle Cerebral Artery Ischaemic Stroke

The importance of assessing the collateral status (CS) in patients with ischaemic stroke (IS) has repeatedly been emphasised in clinical guidelines. Various publications offer qualitative or semiquantitative scales with gradations corresponding to the different extents of the collaterals, visualised mostly on the basis of CTA images. However, information on their inter-rater reliability is limited. Therefore, the aim of this study is to investigate the inter-rater reliability of the scales for collateral assessment. CTA images of 158 patients in the acute period of IS were used in the study. The assessment of CS was performed by two experts using three methodologies: the modified Tan scale, the Miteff scale, and the Rosenthal scale. Cohen's kappa, weighted kappa and Krippendorff's alpha were used as reliability measures. For the modified Tan scale and the Miteff and Rosenthal scales, the weighted kappa values were 0.72, 0.49 and 0.59, respectively. Although the best measure of consistency was found for the modified Tan scale, no statistically significant differences were revealed among the scales. The impact of the CS on the degree of neurological deficit at discharge was shown for the modified Tan and Rosenthal scales. In conclusion, the analysis showed a moderate inter-rater reliability of the three scales, but was not able to distinguish the best one among them.

The Pathophysiology of Collateral Circulation in Acute Ischemic Stroke

Cerebral collateral circulation is a network of blood vessels which stabilizes blood flow and maintains cerebral perfusion whenever the main arteries fail to provide an adequate blood supply, as happens in ischemic stroke. These arterial networks are able to divert blood flow to hypoperfused cerebral areas. The extent of the collateral circulation determines the volume of the salvageable tissue, the so-called "penumbra". Clinically, this is associated with greater efficacy of reperfusion therapies (thrombolysis and thrombectomy) in terms of better short- and long-term functional outcomes, lower incidence of hemorrhagic transformation and of malignant oedema, and smaller cerebral infarctions. Recent advancements in brain imaging techniques (CT and MRI) allow us to study these anastomotic networks in detail and increase the likelihood of making effective therapeutic choices. In this narrative review we will investigate the pathophysiology, the clinical aspects, and the possible diagnostic and therapeutic role of collateral circulation in acute ischemic stroke.

Vascular hyperintensities on baseline FLAIR images are associated with functional outcome in stroke patients with successful recanalization after mechanical thrombectomy

PURPOSE

The purpose of this study was to assess the prognostic value of vascular hyperintensities on FLAIR images (VHF) at admission MRI in patients with acute ischemic stroke (AIS) achieving successful recanalization after mechanical thrombectomy.

MATERIALS AND METHODS

Patients with AIS treated by mechanical thrombectomy following admission MRI from the single-center HIBISCUS-STROKE cohort were assessed for eligibility. VHF were categorized using a four-scale classification and were considered poor when grade < 3 (i.e., absence of distal VHF). Recanalization was considered successful when modified thrombolysis in cerebral infarction score was ≥ 2B Functional outcome was considered poor if modified Rankin scale (mRS) at three months was > 2. Univariable and multiple variable logistic regressions were performed to identify factors associated with poor functional outcome despite successful recanalization.

RESULTS

A total of 108 patients were included. There were 65 men and 43 women with a median age of 70.5 years (interquartile range: 55.0, 81.0; age range: 22.0-93.0 years). Among them, 39 subjects (36.1%) had poor functional outcome at three months. Univariable logistic regressions indicated that poorly extended VHF (VHF grade < 3) were associated with a poor functional outcome (P = 0.008) as well as age, hypertension and diabetes, baseline National Institute of Health Stroke Scale (NIHSS) score, pre-stroke mRS, lack of intravenous thrombolysis, cerebral microangiopathy and the presence of microbleeds. Multivariable analysis confirmed that poor VHF status was independently associated with a poor functional outcome (odds ratio [OR], 4.26; 95% confidence interval [CI]: 1.55-12.99; P = 0.007) in combination with hypertension (OR, 1.25; 95% CI: 0.87-1.85; P = 0.02), baseline NIHSS score (OR, 1.09; 95% CI: 1.04-1.20; P = 0.03), pre-stroke mRS (OR, 2.05; 95% CI: 1.07-4.61; P = 0.05) and lack of intravenous thrombolysis (OR, 0.23; 95% CI: 0.08-0.61; P = 0.004).

CONCLUSION

Poorly extended VHF (grade <3) at admission MRI are associated with a poor functional outcome at three months despite successful recanalization by mechanical thrombectomy.

Identifying large vessel occlusion using the hyperdense artery sign in patients treated with mechanical thrombectomy

OBJECTIVES

The hyperdense artery sign on non-contrast computed tomography-reconstructed images is useful for identifying large vessel occlusion in acute ischemic stroke. This study aimed to assess its efficacy in patients with large vessel occlusion treated with mechanical thrombectomy.

MATERIALS AND METHODS

This retrospective and prospective single-centered study from June 2019 to May 2021 evaluated the use of non-contrast computed tomography-reconstructed images for detecting hyperdense artery sign to identify large vessel occlusion from June 2020 to May 2021. We registered consecutive potential candidates for mechanical thrombectomy due to suspected stroke and assessed the accuracy of hyperdense artery sign on non-contrast computed tomography-reconstructed images for large vessel occlusion in the hyperacute setting. Non-contrast computed tomography images were reconstructed into maximum intensity projection images with iterative reconstruction algorithms to detect hyperdense artery signs. We compared the door-to-puncture time and functional outcome at 90 days before and after employing non-contrast computed tomography-reconstructed images in patients with large vessel occlusion treated with mechanical thrombectomy.

RESULTS

The cohort included 82 patients, wherein 47 were treated with mechanical thrombectomy. The sensitivity (96%) and specificity (94%) of hyperdense artery sign on non-contrast computed tomography-reconstructed images for large vessel occlusion were performed. The door-to-puncture time was significantly shortened after using non-contrast computed tomography-reconstructed images (49 versus 28 min, p = 0.001), but the functional outcome at 90 days remained unchanged.

CONCLUSIONS

Non-contrast computed tomography-reconstructed images, as a vascular imaging tool for mechanical thrombectomy, can reduce workflow time in hospitals by identifying large vessel occlusion with high sensitivity and specificity.

Mothership vs. drip-and-ship: evaluation of initial treatment strategies for acute ischemic stroke in a well-developed network of specialized hospitals

PURPOSE

Two strategies of initial patient care exist in endovascular thrombectomy (ET) depending on the site of initial admission: the mothership (MS) and drip-and-ship (DnS) principles. This study compares both strategies in regard to patient outcome in a local network of specialized hospitals.

METHODS

Two-hundred-and-two patients undergoing ET in anterior circulation ischemic stroke between June 2016 and May 2018 were enrolled. Ninety two patients were directly admitted to our local facility (MS), One-hundred-and-ten were secondarily referred to our facility. Group comparisons between admission strategies in three-months modified Rankin Scale (mRS), Maas Score and Alberta-Stroke-Program-Early-computed-tomography-score (ASPECTS), National-Institutes-of-Health-Stroke-Scale (NIHSS), age and onset-to-recanalization-time were performed. Correlation between admission strategy and mRS was calculated. A binary logistic regression model was computed including mRS as dependent variable.

RESULTS

There were neither significant group differences in three-months mRS between MS and DnS nor significant correlations. Patients tended to achieve a better outcome with DnS. Collateralization status differed between MS and DnS (p = 0.003) with better collateralization in DnS. There were no significant group differences in NIHSS or ASPECTS but in onset-to-recanalization-time (p < 0.001) between MS and DnS. Binary logistic regression showed a high explanation of variance of mRS but no significant results for admission strategy.

CONCLUSIONS

Functional outcome in patients treated with ET is comparable between the MS and DnS principles. Tendentially better outcome in the DnS subgroup may be explained by selection bias due to a higher willingness to apply ET in patients with worse baseline conditions (e.g. worse collateralization), if patients undergoing MS are already on site.

Mechanical thrombectomy in stroke patients with acute occlusion of the M1- compared to the M2-segment: Safety, efficacy, and clinical outcome

PURPOSE

Endovascular treatment (ET) in occlusions of the M1- and proximal M2-segment of the middle cerebral artery (MCA) is an established procedure. In contrast, ET in distal M2-occlusions has not been sufficiently evaluated yet. The purpose of this study was to assess relevant parameters for clinical outcome, efficacy, and safety of patients undergoing ET in M1-, proximal M2-, and distal M2-occlusions.

METHODS

One hundred seventy-four patients undergoing ET in acute ischemic stroke with an occlusion of the M1- or M2-segment of the MCA were enrolled prospectively. Non-parametric analysis of variance in 3-month mRS, TICI scale, and complication rates were performed with Kruskal-Wallis test between M1- and proximal and distal M2-occlusions. Subsequent pairwise group comparisons were calculated using Mann-Whitney U-tests. Binary logistic regression models were calculated for each occlusion site.

RESULTS

There were no significant group differences in 3-month mRS, mTICI scale, or complication rates between M1- and M2-occlusions nor between proximal and distal M2-occlusions. Binary logistic regression in patients with M1-occlusions showed a substantial explanation of variance (NR2=0.35). NIHSS (p=0.009) and Maas Score as parameter for collateralization (p=0.01) appeared as significant contributing parameters. Binary logistic regression in M2-occlusions showed a high explanation of variance (NR2=0.50) of mRS but no significant factors.

CONCLUSIONS

Clinical outcome and procedural safety of patients with M2-occlusions undergoing ET are comparable to those of patients with M1-occlusions. Clinical outcome of patients with M1-occlusions undergoing ET is primarily influenced by the initial neurological deficit and the collateralization of the occlusions. By contrast, clinical outcome in patients with M2-occlusions undergoing ET is more multifactorial.

Predicting futile recanalization, malignant cerebral edema, and cerebral herniation using intelligible ensemble machine learning following mechanical thrombectomy for acute ischemic stroke

Purpose

To establish an ensemble machine learning (ML) model for predicting the risk of futile recanalization, malignant cerebral edema (MCE), and cerebral herniation (CH) in patients with acute ischemic stroke (AIS) who underwent mechanical thrombectomy (MT) and recanalization.

Methods

This prospective study included 110 patients with premorbid mRS ≤ 2 who met the inclusion criteria. Futile recanalization was defined as a 90-day modified Rankin Scale score &gt;2. Clinical and imaging data were used to construct five ML models that were fused into a logistic regression algorithm using the stacking method (LR-Stacking). We added the Shapley Additive Explanation method to display crucial factors and explain the decision process of models for each patient. Prediction performances were compared using area under the receiver operating characteristic curve (AUC), F1-score, and decision curve analysis (DCA).

Results

A total of 61 patients (55.5%) experienced futile recanalization, and 34 (30.9%) and 22 (20.0%) patients developed MCE and CH, respectively. In test set, the AUCs for the LR-Stacking model were 0.949, 0.885, and 0.904 for the three outcomes mentioned above. The F1-scores were 0.882, 0.895, and 0.909, respectively. The DCA showed that the LR-Stacking model provided more net benefits for predicting MCE and CH. The most important factors were the hypodensity volume and proportion in the corresponding vascular supply area.

Conclusion

Using the ensemble ML model to analyze the clinical and imaging data of AIS patients with successful recanalization at admission and within 24 h after MT allowed for accurately predicting the risks of futile recanalization, MCE, and CH.

Collateral Capacity Assessment : Robustness and Interobserver Agreement of Two Grading Scales and Agreement with Quantitative Scoring

BACKGROUND AND PURPOSE

Intracranial collateral capacity is conducive to imply parenchymal perfusion of affected territory after acute vessel occlusion. The Tan collateral score is commonly used to assess the intracranial collateral capacity; however, this score is coarsely grained and interobserver agreement is low, which reduces prognostic value and clinical utility. We introduce and evaluate an alternative extended Tan score based on the conventional Tan scale and assess the agreement with a quantitative score.

METHODS

We included 100 consecutive patients with a proven acute single large vessel occlusion of the proximal anterior circulation. Collaterals were graded with the conventional and extended Tan score and an automated quantitative score. The extended Tan score is a finer 6‑scale manual score based on the conventional 4‑point Tan scale. The quantitative score is calculated by an automatic software package (StrokeViewer). Interobserver agreement of the manual scores was assessed with the weighted kappa. The Spearman correlation coefficient was calculated to determine the agreement between the manual and automated collateral scores.

RESULTS

The interobserver agreement was higher for the extended score than for the conventional score with a weighted kappa of 0.70 and 0.65, respectively. For the extended and conventional score, the Spearman correlation coefficient for the agreement with the automated score was 0.78 and 0.76, respectively.

CONCLUSION

Because of the good interobserver agreement and good agreement with quantitative assessment, the extended collateral score is a strong candidate to improve prognostic value of collateral assessment and implementation in clinical practice.

The value of whole-brain CT perfusion imaging combined with dynamic CT angiography in the evaluation of pial collateral circulation with middle cerebral artery occlusion

BACKGROUND

Middle cerebral artery (MCA) occlusion is extremely common, especially unilateral artery, which can result in a significant incidence of cerebral infarction.

OBJECTIVE

To assess the value of whole-brain computed tomography perfusion (CTP) imaging combined with dynamic CT angiography (dCTA) in the evaluation of pial collateral circulation in patients with MCA occlusion.

METHODS

Whole-brain CTP and dCTA images were acquired in 58 patients with unilateral MCA occlusion. All patients were divided into three groups according to the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) collateral score (by CTA). The CTP parameters were analysed, including relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), relative mean transit time (rMTT), and relative time to peak (rTTP). Patients were followed up with the modified Rankin scale (mRS). All cases in this study were confirmed by DSA.

RESULTS

The CTP parameters of the MCA blood supply area on the affected side of patients with different degrees of stenosis were significantly different from those on the unaffected side. There are significant differences in the CTP parameters and openings of the Willis circle in patients with different degrees of stenosis. Significant differences were found in the number of patients with good prognosis.

CONCLUSIONS

Whole-brain CT perfusion combined with dynamic CTA can structurally and functionally evaluate the establishment of pial collateral circulation and its effect on cerebral hemodynamic changes.

Inter-rater reliability for assessing intracranial collaterals in patients with acute ischemic stroke: comparing 29 raters and an artificial intelligence-based software

Purpose

Outcome of endovascular treatment in acute ischemic stroke patients is depending on the collateral circulation maintaining blood flow to the ischemic territory. We evaluated the inter-rater reliability and accuracy of raters and an automated algorithm for assessing the collateral score (CS, range: 0–3) in acute ischemic stroke patients.

Methods

Baseline CTA scans with an intracranial anterior occlusion from the MR CLEAN study (n=500) were used. For each core lab CS, ten CTA scans with sufficient quality were randomly selected. After a training session in collateral scoring, all selected CTA scans were individually evaluated for a visual CS by three groups: 7 radiologists, 13 junior and 9 senior radiology residents. Two additional radiologists scored CS to be used as reference, with a third providing a CS to produce a 2 out of 3 consensus CS in case of disagreement. An automated algorithm was also used to compute CS. Inter-rater agreement was reported with intraclass correlation coefficient (ICC). Accuracy of visual and automated CS were calculated.

Results

39 CTA scans were assessed (1 corrupt CTA-scan excluded). All groups showed a moderate ICC (0.689-0.780) in comparison to the reference standard. Overall human accuracy was 65± 7% and increased to 88± 5% for dichotomized CS (0–1, 2–3). Automated CS accuracy was 62%, and 90% for dichotomized CS. No significant difference in accuracy was found between groups with different levels of expertise.

Conclusion

After training, inter-rater reliability in collateral scoring was not influenced by experience. Automated CS performs similar to residents and radiologists in determining a collateral score.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00234-022-02984-z.

Visualization of the Anterior Temporal Artery as a Predictor of Outcome in Middle Cerebral Artery Occlusion Patients Achieving Successful Recanalization After Transfer

Introduction

Anterior temporal artery (ATA) visualization on computed tomography angiography (CTA) has been previously associated with good outcomes in middle cerebral artery (MCA) occlusions, but not in the setting of patients who initially present to non-thrombectomy centers.

Methods

We retrospectively identified acute MCA (M1) occlusion patients who underwent mechanical thrombectomy after transfer from non-thrombectomy-capable centers. Neuroradiologists confirmed the MCA (M1) as the most proximal site of occlusion on CTA and assessed for visualization of the ATA. Thrombolysis in Cerebral Infarction (TICI) 2b or greater revascularization scores were confirmed by neurointerventionalists blinded to patient outcomes. Ninety-day modified Rankin scale (mRS) scores were obtained via a structured telephone questionnaire.

Results

We identified 102 M1 occlusion patients over a three-and-a-half-year period presenting to a non-thrombectomy-capable center who underwent transfer and mechanical thrombectomy. There were no significant differences in age, gender, race, comorbidities, or median National Institute of Health Stroke Scale (NIHSS) scores between the ATA visualized (n = 47) versus non-visualized (n = 55) cohort, and no significant differences in baseline Alberta Stroke Program Early Computed Tomography (ASPECT) scores, post-intervention TICI scores, or interval from last known well to revascularization. There was a strong trend in functional independent outcome (mRS ≤ 2) for patients with ATA visualization (63.8% vs. 45.5%, p = 0.064).

Conclusion

For patients presenting to non-thrombectomy centers without CT perfusion capability, ATA visualization should be further investigated as an outcome predictor, given its association with functional independence after successful recanalization.

This article was previously presented as a meeting abstract at the 2021 International Stroke Conference on March 17-19, 2021.

Evolution of Hypodensity on Non-Contrast CT in Correlation with Collaterals in Anterior Circulation Stroke with Successful Endovascular Reperfusion

Introduction: The aim of the study was to assess the impact of collaterals on the evolution of hypodensity on non-contrast CT (NCCT) in anterior circulation stroke with reperfusion by mechanical thrombectomy (MT). Methods: We retrospectively included stroke patients with middle cerebral artery occlusion who were reperfused by MT in early and late time window. Artificial intelligence (AI)-based software was used to calculate of hypodensity volumes at baseline NCCT (V1) and at follow-up NCCT 24 h after MT (V2), along with the difference between the two volumes (V2-V1) and the follow-up (V2)/baseline (V1) volume ratio (V2/V1). The same software was used to classify collateral status by using a 4-point scale where the score of zero indicated no collaterals and the score of three represented contrast filling of all collaterals. The volumetric values were correlated with the collateral scores. Results: Collateral scores had significant negative correlation with V1 (p = 0.035), V2, V2− V1 and V2/V1 (p < 0.001). In cases with collateral score = 3, V2 was significantly smaller or absent compared to V1; in those with collateral score 2, V2 was slightly larger than V1, and in those with scores 1 and 0 V2 was significantly larger than V1. These relationships were observed in both early and late time windows. Conclusions: The collateral status determined the evolution of the baseline hypodensity on NCCT in patients with anterior circulation stroke who had MT reperfusion. Damage can be stable or reversible in patients with good collaterals while in those with poor collaterals tissues that initially appear normal will frequently appear as necrotic after 24 h. With good collaterals, it is stable or can be reversible while with poor collaterals, normal looking tissue frequently appears as necrotic in follow-up exam. Hence, acute hypodensity represents different states of the ischemic brain parenchyma.

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.

A meta-analysis of collateral status and outcomes of mechanical thrombectomy

OBJECTIVES

To perform a systematic review and meta-analysis to investigate pretreatment collaterals and outcomes of mechanical thrombectomy in patients with acute ischemic stroke of large-vessel occlusion in anterior circulation.

METHODS

We systematically searched Embase, PubMed, and the Cochrane Library from their dates of inception to March 5, 2020, and also manually searched reference lists of relevant articles. Pooled relative risk with 95% confidence interval on the association between good collaterals and functional independence (in terms of mRS 0-2), symptomatic intracranial hemorrhage, mortality, and successful reperfusion were synthesized using a random-effects model.

RESULTS

Thirty-four studies enrolling 5768 patients were included in analysis. Good collaterals were significantly associated with functional independence (RR 1.93, 95%CI 1.64-2.27, P < .0001), successful reperfusion (RR 1.23, 95%CI 1.12-1.35, P < .0001), decreased rate of symptomatic intracranial hemorrhage (RR 0.68, 95%CI 0.47-0.97, P = .032), and mortality (RR 0.37, 95%CI 0.27-0.52, P < .0001). The results were consistent in sensitivity analysis. The associations between good collaterals and reperfusion remained stable after adjusting for publication bias.

CONCLUSIONS

Good pretreatment collaterals were associated with functional independence, successful reperfusion, and decreased rate of sICH and mortality after receiving mechanical thrombectomy in patients with acute ischemic stroke of large-vessel occlusion.

Predictors of poor clinical outcome despite complete reperfusion in acute ischemic stroke patients

BACKGROUND

In patients suffering from acute ischemic stroke from large vessel occlusion (LVO), mechanical thrombectomy (MT) often leads to successful reperfusion. Only approximately half of these patients have a favorable clinical outcome. Our aim was to determine the prognostic factors associated with poor clinical outcome following complete reperfusion.

METHODS

Patients treated with MT for LVO from a prospective single-center stroke registry between July 2015 and April 2019 were screened. Complete reperfusion was defined as Thrombolysis in Cerebral Infarction (TICI) grade 3. A modified Rankin scale at 90 days (mRS90) of 3-6 was defined as 'poor outcome'. A logistic regression analysis was performed with poor outcome as a dependent variable, and baseline clinical data, comorbidities, stroke severity, collateral status, and treatment information as independent variables.

RESULTS

123 patients with complete reperfusion (TICI 3) were included in this study. Poor clinical outcome was observed in 67 (54.5%) of these patients. Multivariable logistic regression analysis identified greater age (adjusted OR 1.10, 95% CI 1.04 to 1.17; p=0.001), higher admission National Institutes of Health Stroke Scale (NIHSS) (OR 1.14, 95% CI 1.02 to 1.28; p=0.024), and lower Alberta Stroke Program Early CT Score (ASPECTS) (OR 0.6, 95% CI 0.4 to 0.84; p=0.007) as independent predictors of poor outcome. Poor outcome was independent of collateral score.

CONCLUSION

Poor clinical outcome is observed in a large proportion of acute ischemic stroke patients treated with MT, despite complete reperfusion. In this study, futile recanalization was shown to occur independently of collateral status, but was associated with increasing age and stroke severity.

Predictors for the extent of pial collateral recruitment in acute ischemic stroke

BACKGROUND

Pial arterioles can provide a variable degree of collateral flow to ischemic vascular territories during acute ischemic stroke. This study sought to identify predictive factors of the degree of pial collateral recruitment in acute ischemic stroke.

METHODS

Clinical information and arteriograms from 62 consecutive patients with stroke due to either middle cerebral artery (MCA) M1 segment or internal carotid artery (ICA) terminus occlusion within 6 h following symptom onset were retrospectively reviewed. Pial collaterals were defined based on the extent of reconstitution of the MCA territory. Patients with slow antegrade flow distal to the occlusion site were excluded and no anesthetics were used prior or during angiography. Results were analyzed using multivariate nominal logistic regression.

RESULTS

Better pial collateral recruitment was associated with proximal MCA versus ICA terminus occlusion (p = 0.005; odds ratio (OR) = 9.3; 95% confidence interval (CI), 2.16-53.3), lower presenting National Institutes of Health Stroke Scale Score (NIHSSS) (p = 0.023; OR = 6.51; 95% CI, 1.49-41.7), and lower diastolic blood pressure (p = 0.0411; OR = 5.05; 95% CI, 1.20-29.2). Age, gender, symptom duration, diabetes, laterality, systolic blood pressure, glucose level, hematocrit, platelet level, and white blood cell count at presentation were not found to have a statistically significant association with pial collateral recruitment.

CONCLUSIONS

Extent of pial collateral recruitment is strongly associated with the occlusion site (MCA M1 segment versus ICA terminus) and less strongly associated with presenting NIHSSS and diastolic blood pressure.