Effect of Collaterals on Clinical Presentation, Baseline Imaging, Complications, and Outcome in Acute Stroke

The Los Angeles motor scale (LAMS) is independently associated with CT perfusion collateral status markers

BACKGROUND AND AIM

The Los Angeles Motor Scale (LAMS) is an objective tool that has been used to rapidly assess and predict the presence of large vessel occlusion (LVO) in the pre-hospital setting successfully in several studies. However, studies assessing the relationship between LAMS score and CT perfusion collateral status (CS) markers such as cerebral blood volume (CBV) index, and hypoperfusion intensity ratio (HIR) are sparse. Our study therefore aims to assess the association of admission LAMS score with established CTP CS markers CBV Index and HIR in AIS-LVO cases.

MATERIALS AND METHODS

In this prospectively collected, retrospectively reviewed analysis, inclusion criteria were as follows: a) CT angiography (CTA) confirmed anterior circulation LVO from 9/1/2017 to 10/01/2023, and b) diagnostic CT perfusion (CTP). Logistic regression analysis was performed to assess the relationship between admission LAMS with CTP CS markers HIR and CBV Index. p ≤ 0.05 was considered significant.

RESULTS

In total, 285 consecutive patients (median age = 69 years; 56 % female) met our inclusion criteria. Multivariable logistic regression analysis adjusting for sex, age, ASPECTS, tPA, premorbid mRS, admission NIH stroke scale, prior history of TIA, stroke, atrial fibrillation, diabetes mellitus, hyperlipidemia, coronary artery disease and hypertension, admission LAMS was found to be independently associated with CBV Index (adjusted OR:0.82, p < 0.01), and HIR (adjusted OR:0.59, p < 0.05).

CONCLUSION

LAMS is independently associated with CTP CS markers, CBV index and HIR. This finding suggests that LAMS may also provide an indirect estimate of CS.

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.

Anatomical variations in the circle of Willis on magnetic resonance angiography in a south Trinidad population

Objectives

This article seeks to determine the prevalence of a complete circle of Willis (CoW) and its common morphological variations in a south Trinidad population, while also investigating the influence of gender, age, and ethnicity on CoW morphology.

Methods

A prospective, descriptive, cross-sectional study was done on the magnetic resonance images for consecutive patients who had a brain MRI/magnetic resonance angiography at a tertiary health institution in south Trinidad between October 2019 and September 2020. Patients with significant cerebrovascular disease and/or a history of prior neurosurgical intervention were excluded.

Results

A complete CoW was seen in 24.3%, with more complete circles observed in younger participants (≤45 years) and Afro-Trinidadians. No gender predilection for a complete CoW was demonstrated. The most common variations in the anterior and posterior parts of the circle were a hypoplastic anterior communicating artery (8.6%, n = 13) and bilateral aplastic posterior communicating arteries (18.4%, n = 28), respectively.

Conclusions

Significant variations exist in the CoW of a south Trinidad population with a frequency of complete in 24.3%, and more complete circles in younger patients and Afro-Trinidadians. Gender did not influence CoW morphology.

Advances in knowledge

Structural abnormalities in the CoW may be linked to future incidence of cerebrovascular diseases and should therefore be communicated to the referring physician in the written radiology report. Knowledge of variant anatomy and its frequency for a particular populations is also required by neurosurgeons and neuro-interventional radiologists to help with preprocedural planning and to minimize complications.

Significant Slowed Cortical Venous Blood Flow in Patients with Acute Ischemic Stroke with Large Vessel Occlusion Suggests Poor Collateral Circulation and Prognosis

RATIONALE AND OBJECTIVES

To investigate the change of cortical venous flow in acute ischemic stroke patients with large vessel occlusion (LVO-AIS) and its clinical value.

MATERIALS AND METHODS

Baseline whole-brain 4D-CTA/CTP and clinical data of LVO-AIS and a control group were collected from June 2020 to October 2021. Venous inflow time (VIT), venous peak time (VPT), and venous outflow time (VOT) were analyzed on both sides of patients and normal controls. The VIT/VPT/VOT were statistically described and compared between the patient group and normal controls, then, in patients with different collateral circulation and prognoses. Next, the correlation between cortical venous drainage time and collateral circulation grading was analyzed. Finally, logistic regression analysis was used to explore the relationship between the three venous times and prognosis, and receiver operating characteristic (ROC) curves were plotted to assess the value of delayed cortical venous imaging in predicting prognosis.

RESULTS

149 LVO-AIS and 73 normal controls were collected. VIT, VPT, and VOT were significantly delayed on the affected side in the patient group compared with the healthy side (p<0.05) and the controls (p<0.05); VIT and VPT were also significantly delayed on the healthy side of patients compared with the controls (p<0.05). Delayed VIT and VPT on the affected side in the patient group were more significant in patients with poor collateral circulation (p<0.05), and VIT and VPT on the affected side in the patient group were negatively correlated with arterial collateral scores. VIT and VPT were significantly delayed in both sides of patients in the poor prognosis group compared with the good prognosis group (p<0.05). logistic regression showed that patients' affected VPT, arterial collateral scores, and NIHSS were independent predictors of poor prognosis, with an accuracy of 79.6% in predicting poor prognosis. The affected VPT and NIHSS were independent predictors of poor prognosis for patients presenting within 24 hours, with an accuracy of 79.6% in predicting poor prognosis.

CONCLUSION

Cortical venous flow was significantly slowed in both sides of LVO-AIS patients. delayed ipsilateral VPT in LVO-AIS patients can be used as an imaging indicator to determine poor collateral circulation and predict poor prognosis.

Head Down Tilt 15° in Acute Ischemic Stroke with Poor Collaterals: A Randomized Preclinical Trial

Cerebral collaterals are recruited after arterial occlusion with a protective effect on tissue outcome in acute ischemic stroke. Head down tilt 15° (HDT15) is a simple, low cost and accessible procedure that could be applied as an emergency treatment, before recanalization therapies, with the aim to increase cerebral collateral flow. Spontaneously hypertensive rats have been shown to display anatomical differences in morphology and function of cerebral collaterals, compared to other rat strains, resulting in an overall poor collateral circulation. We investigate the efficacy and safety of HDT15 in spontaneously hypertensive (SHR) rats, which were considered as an animal stroke model with poor collaterals. Cerebral ischemia was induced by 90 minute endovascular occlusion of the middle cerebral artery (MCA). SHR rats were randomized to HDT15 or flat position (n = 19). HDT15 was applied 30 minutes after occlusion and lasted 60 minutes, until reperfusion. HDT15 application increased cerebral perfusion (+16.6% versus +6.1%; p = 0.0040) and resulted in a small reduction of infarct size (83.6 versus 107.1 mm3; - 21.89%; p = 0.0272), but it was not associated with early neurological improvement, compared to flat position. Our study suggests that the response to HDT15 during MCA occlusion is dependent on baseline collaterals. Nonetheless, HDT15 promoted a mild improvement of cerebral hemodynamics even in subjects with poor collaterals, without safety concerns.

Comparison of Three Algorithms for Predicting Infarct Volume in Patients with Acute Ischemic Stroke by CT Perfusion Software: Bayesian, CSVD, and OSVD

This study aimed to compare the performance of the Bayesian probabilistic method, circular Singular Value Decomposition (cSVD), and oscillation index Singular Value Decomposition (oSVD) algorithms in Olea Sphere for predicting infarct volume in patients with acute ischemic stroke (AIS). Eighty-seven patients suffering from AIS with large vessel occlusion were divided into improvement and progression groups. The improvement group included patients with successful recanalization (TICI 2b-3) after thrombectomy or whose clinical symptoms improved after thrombolysis. The progression group consisted of patients whose clinical symptoms did not improve or even got worse. The infarct core volume from the Olea Sphere software was used as the predicted infarct volume (PIV) in the improvement group, whereas the hypoperfusion volume was used as the PIV in the progression group. We defined predicted difference (PD) as PIV minus final infarct volume (FIV) measured at follow-up imaging. Differences among the three algorithms were assessed by the Friedman test. Spearman correlation analysis was used to verify the correlation between PIV and FIV. In addition, we performed a subgroup analysis of the progression group based on collateral circulation status. The median [interquartile range (IQR)] of the PD and Spearman correlation coefficients (SCCs) between PIV and FIV for the improvement group (n = 22) were: Bayesian = [6.99 (-14.72, 18.99), 0.500]; oSVD = [-12.74 (-41.06, -3.46), 0.423]; cSVD = [-15.38 (-38.92, -4.68), 0.586]. For the progression group (n = 65), the median (IQR) of PD and SCCs were: Bayesian = [1.00 (-34.07, 49.37), 0.748]; oSVD = [-0.17 (-53.42, 29.73), 0.712]; cSVD = [66.55 (7.94, 106.32), 0.674]. The Bayesian algorithm in the Olea Sphere software predicted infarct volumes with better accuracy and stability than the other two algorithms in both the progression and improvement groups.

Assessing the Relationship between LAMS and CT Perfusion Parameters in Acute Ischemic Stroke Secondary to Large Vessel Occlusion

BACKGROUND

The Los Angeles Motor Scale (LAMS) is a rapid pre-hospital scale used to predict stroke severity which has also been shown to accurately predict large vessel occlusions (LVOs). However, to date there is no study exploring whether LAMS correlates with the computed tomography perfusion (CTP) parameters in LVOs.

METHODS

Patients with LVO between September 2019 and October 2021 were retrospectively reviewed and included if the CTP data and admission neurologic exams were available. The LAMS was documented based on emergency personnel exams or scored retrospectively using an admission neurologic exam. The CTP data was processed by RAPID (IschemaView, Menlo Park, CA, USA) with an ischemic core volume (relative cerebral blood flow [rCBF] < 30%), time-to-maximum (Tmax) volume (Tmax > 6 s delay), hypoperfusion index (HI), and cerebral blood volume (CBV) index. Spearman's correlations were performed between the LAMS and CTP parameters.

RESULTS

A total of 85 patients were included, of which there were 9 intracranial internal carotid artery (ICA), 53 proximal M1 branch middle cerebral artery M1, and 23 proximal M2 branch occlusions. Overall, 26 patients had LAMS 0-3, and 59 had LAMS 4-5. In total, LAMS positively correlated with CBF < 30% (Correlation Coefficient (CC): 0.32, p < 0.01), Tmax > 6 s (CC:0.23, p < 0.04), HI (CC:0.27, p < 0.01), and negatively correlated with the CBV index (CC:-0.24, p < 0.05). The relationships between LAMS and CBF were < 30% and the HI was more pronounced in M1 occlusions (CC:0.42, p < 0.01; 0.34, p < 0.01 respectively) and proximal M2 occlusions (CC:0.53, p < 0.01; 0.48, p < 0.03 respectively). The LAMS also correlated with a Tmax > 6 s in M1 occlusions (CC:0.42, p < 0.01), and negatively correlated with the CBV index in M2 occlusions (CC:-0.69, p < 0.01). There were no significant correlations between the LAMS and intracranial ICA occlusions.

CONCLUSIONS

The results of our preliminary study indicate that the LAMS is positively correlated with the estimated ischemic core, perfusion deficit, and HI, and negatively correlated with the CBV index in patients with anterior circulation LVO, with stronger relationships in the M1 and M2 occlusions. This is the first study showing that the LAMS may be correlated with the collateral status and estimated ischemic core in patients with LVO.

Proposal of multimodal computed tomography-based scoring system in prediction of hemorrhagic transformation in acute ischemic stroke

INTRODUCTION

The routinely used computed tomography (CT)-based workup in the setting of acute ischemic stroke (AIS) includes non-contrast brain CT, CT angiography (CTA), and CT perfusion. Several CT, CTA, CTP-based radiological biomarkers of hemorrhagic transformation (HT) were reported.

AIM OF THE STUDY

To assess the predictive value of the combined multimodal CT parameters for HT after AIS and proposal of predictive scoring scale.

METHODS

The source images of the NCCT, CTA and CTP of 282 AIS patients involving the anterior circulation (HT = 91, non-HT = 191) were retrospectively reviewed and the following biomarkers were recorded and analyzed: Early subtle ischemic signs, hyperdense middle cerebral artery sign (HMCAS) and Alberta Stroke Program Early CT Score (ASPECTS) < 7 in NCCT, large-vessel occlusion (LVO), clot burden score (CBS) < 6, large-vessel occlusion, poor collateral score (CS) and Tmax > 6 s ≥ 56.5 ml. A scoring system to predict HT based on these biomarkers was developed. Each biomarker counts for a single point with the total score ranging from 0 to 7.

RESULTS

All the aforementioned multimodal CT biomarkers and the selected cut offs were significantly associated with higher HT risk. The calculated scores were statistically significant different between the HT and the non-HT groups with AUC 0.761 (95% CI 0.703-0.819, P < 0.0000001). Rates of HT were approximately five times higher in patients with score ≥ 3.

CONCLUSION

Multimodal CT-based scoring system may provide highly reliable predictive model of hemorrhagic transformation in acute ischemic stroke.

Risk Factors and Functional Outcomes with Early Neurological Deterioration after Mechanical Thrombectomy for Acute Large Vessel Occlusion Stroke

Early neurological deterioration (END) is associated with a poor survival after mechanical thrombectomy (MT) in acute ischemic stroke (AIS). To assess risk factors and functional outcomes of END after MT in patients, we analyzed data from 79 patients who received MT with large-vessel occlusion. END after MT in patients is defined as an increase of two points or more in the National Institute of Health Stroke Scale (NIHSS) score, compared with the best neurological status within 7 days. The mechanism of END can be classified into: AIS progression, sICH, and encephaledema. A total of 32 AIS patients (40.5%) had END after MT. Risk factors for END after MT included: history of oral antiplatelet and/or anticoagulation drugs before MT (OR = 9.56,95% CI = 1.02-89.57), higher NIHSS score when admitted to hospital (OR = 1.24, 95% CI = 1.04-1.48), under the subtype of atherosclerotic stroke (OR = 17.36, 95% CI = 1.51-199.56), ASITN/SIR< 2 (OR = 15.78, 95% CI = 1.65-151.26), and prolonged period from AIS onset to the first revascularization (OR = 1.01, 95% CI = 1.00-1.02). AIS patients who had END at early stages were more likely to experience poor outcomes (Modified Rankin Scale [mRS] >2) at 90 days after MT (OR = 6.829, 95% CI = 1.573-29.655). Thus, AIS patients who had experienced END at early stages were more likely to have poor outcomes (mRS >2) at 90 days after MT, and the risk factors of END were connected to the mechanism of END.

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.

Prognostic accuracy and impact of cerebral collateral status on clinical and safety outcomes in acute ischemic stroke patients receiving reperfusion therapy: a systematic meta-analysis

BACKGROUND

Cerebral collateral status has a potential role in mediating postreperfusion clinical and safety outcomes in acute ischemic stroke (AIS).

PURPOSE

To investigate the prognostic accuracy and impact of collateral status on clinical and safety outcomes in patients with AIS receiving reperfusion therapy.

MATERIAL AND METHODS

Studies with AIS patients treated with reperfusion therapy, collateral status assessed using Tan, ASITN/SIR, or similar collateral grading methods and data stratified according to collateral status were included. Relevant data on clinical outcomes, such as functional outcome at 90 days, mortality at 90 days, angiographic reperfusion, symptomatic intracerebral hemorrhage (sICH) and hemorrhagic transformation (HT), were collated and analyzed.

RESULTS

A meta-analysis of 18 studies involving 4132 patients with AIS was conducted. Good collateral status was significantly associated with angiographic reperfusion (odds ratio [OR]=1.97, 95% confidence interval [CI]=1.38-2.80; P < 0.0001), sICH (OR=0.67, 95% CI=0.46-0.99; P = 0.042), and 90-day functional outcome (OR=3.05, 95% CI=1.78-5.24; P < 0.0001). However, its association with HT (OR=0.76, 95% CI=0.38-1.51; P = 0.425) and three-month mortality (OR=0.53, 95% CI=0.17-1.69; P = 0.280) did not reach statistical significance. The prognostic accuracy of collaterals for predicting angiographic reperfusion, HT, functional outcome (at 90 days), and mortality (at 90 days) were 63%, 49%, 66%, and 48%, respectively.

CONCLUSION

Cerebral collaterals are significantly associated with clinical and safety outcomes, albeit with a prognostic accuracy range of 48%-66%; thus, evaluation of their patency is a useful prognostic tool in patients with AIS receiving reperfusion therapy.

Symmetric collateral pattern on CTA predicts favorable outcomes after endovascular thrombectomy for large vessel occlusion stroke

Endovascular thrombectomy (EVT) has revolutionized large vessel occlusion (LVO) stroke management, but often requires advanced imaging. The collateral pattern on CT angiograms may be an alternative because a symmetric collateral pattern correlates with a slowly growing, small ischemic core. We tested the hypothesis that such patients will have favorable outcomes after EVT. Consecutive patients (n = 74) with anterior LVOs who underwent EVT were retrospectively analyzed. Inclusion criteria were available CTA and 90-day modified Rankin Scale (mRS). CTA collateral patterns were symmetric in 36%, malignant in 24%, or other in 39%. Median NIHSS was 11 for symmetric, 18 for malignant, and 19 for other (p = 0.02). Ninety-day mRS ≤2, indicating independent living, was achieved in 67% of symmetric, 17% of malignant, and 38% of other patterns (p = 0.003). A symmetric collateral pattern was a significant determinant of 90-day mRS ≤2 (aOR = 6.62, 95%CI = 2.24,19.53; p = 0.001) in a multivariable model that included age, NIHSS, baseline mRS, thrombolysis, LVO location, and successful reperfusion. We conclude that a symmetric collateral pattern predicts favorable outcomes after EVT for LVO stroke. Because the pattern also marks slow ischemic core growth, patients with symmetric collaterals may be suitable for transfer for thrombectomy. A malignant collateral pattern is associated with poor clinical outcomes.

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.

Correlation of Collateral Scores Derived from Whole-Brain Time-Resolved Flat Panel Detector Imaging in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Flat panel detector CT imaging allows simultaneous acquisition of multiphase flat panel CTA and flat panel CTP imaging directly in the angio suite. We compared collateral assessment derived from multiphase flat panel CTA and flat panel CTP with collateral assessment derived from DSA as the gold-standard.

MATERIALS AND METHODS

We performed a retrospective analysis of patients with occlusion of the first or second segment of the MCA who underwent pre-interventional flat panel detector CT. The hypoperfusion intensity ratio as a correlate of collateral status was calculated from flat panel CTP (time-to-maximum > 10 seconds volume/time-to-maximum > 6 seconds volume). Intraclass correlation coefficients were calculated for interrater reliability for the Calgary/Menon score for multiphase flat panel CTA and for the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) score for DSA collateral scores. Correlations of the hypoperfusion intensity ratio, multiphase flat panel CTA score, and the ASITN/SIR score were calculated using the Spearman correlation.

RESULTS

From November 2019 to February 2020, thirty patients were included. Moderate interrater reliability was achieved for the ASITN/SIR DSA score (0.68; 95% CI, 0.50-0.82) as well as for the Calgary/Menon multiphase flat panel CTA score (0.53; 95% CI, 0.29-0.72). We found a strong correlation between the ASITN/SIR DSA and Calgary/Menon multiphase flat panel CTA score (ρ = 0.54, P = .002) and between the hypoperfusion intensity ratio and the Calgary/Menon multiphase flat panel CTA score (ρ = -0.57, P < .001). The correlation was moderate between the hypoperfusion intensity ratio and the ASITN/SIR DSA score (ρ = -0.49, P = .006). The infarct core volume correlated strongly with the Calgary/Menon multiphase flat panel CTA score (ρ = -0.66, P < .001) and the hypoperfusion intensity ratio (ρ = 0.76, P < .001) and correlated moderately with the ASITN/SIR DSA score (ρ = -0.46, P = .01).

CONCLUSIONS

The Calgary/Menon multiphase flat panel CTA score and the hypoperfusion intensity ratio correlated with each other and with the ASITN/SIR DSA score as the gold-standard. In our cohort, the collateral scoring derived from flat panel detector CT was clinically reliable.

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.

TGFβ1 as a Predictive Biomarker for Collateral Formation Within Ischemic Moyamoya Disease

Objective

Moyamoya disease (MMD) is a unique cerebrovascular occlusive disease characterized by progressive steno-occlusion within the terminal segment of the internal carotid artery. However, good collaterals from an external carotid artery are essential to compensate for the ischemia in moyamoya disease. This study aimed to investigate the transforming growth factor-beta 1 (TGFβ1) in plasma as a potential biomarker for predicting collateral formation in ischemic MMD.

Methods

The transcriptome profile downloaded from Gene Expression Omnibus (GEO) was used to analyze the differential expression of genes between the ischemic MMD and the control groups. We prospectively recruited 23 consecutive patients with ischemic MMD that was diagnosed via digital subtraction angiography (DSA). Nine patients with intracranial aneurysms and four healthy people served as controls. The collaterals from the external carotid artery were examined using DSA. We evaluated whether the collateral formation was associated with TGFβ1 in patients with ischemic MMD. Western blot, RT-qPCR, ELISA, and tube formation assay were used to explore the relationship between TGFβ1 and angiogenesis, as well as the potential mechanisms.

Results

The mRNA levels of TGFβ1 were upregulated in the patients with ischemic MMD. The plasma TGFβ1 levels were higher in the patients with ischemic MMD than in the aneurysm and healthy patients (p < 0.05). The collateral formation group has higher levels of serum TGFβ1 than the non-collateral formation group (p < 0.05). The levels of vascular endothelial growth factor (VEGF) are positively correlated with TGFβ1 levels in the plasma (R² = 0.6115; p < 0.0001). TGFβ1 regulates VEGF expression via the activation of the TGFβ pathway within HUVEC cells, as well as TGFβ1 stimulating HUVEC cells to secrete VEGF into the cell culture media. An in vitro assay revealed that TGFβ1 promotes angiogenesis within the endothelial cells.

Conclusion

Our findings suggest that TGFβ1 plays a vital role in promoting collateral formation by upregulating VEGF expression in ischemic MMD.

Merging Multiphase CTA Images and Training Them Simultaneously with a Deep Learning Algorithm Could Improve the Efficacy of AI Models for Lateral Circulation Assessment in Ischemic Stroke

We aimed to build a deep learning-based, objective, fast, and accurate collateral circulation assessment model. We included 92 patients who had suffered acute ischemic stroke (AIS) with large vessel occlusion in the anterior circulation in this study, following their admission to our hospital from June 2020 to August 2021. We analyzed their baseline whole-brain four-dimensional computed tomography angiography (4D-CTA)/CT perfusion. The images of the arterial, arteriovenous, venous, and late venous phases were extracted from 4D-CTA according to the perfusion time–density curve. The subtraction images of each phase were created by subtracting the non-contrast CT. Each patient was marked as having good or poor collateral circulation. Based on the ResNet34 classification network, we developed a single-image input and a multi-image input network for binary classification of collateral circulation. The training and test sets included 65 and 27 patients, respectively, and Monte Carlo cross-validation was employed for five iterations. The network performance was evaluated based on its precision, accuracy, recall, F1-score, and AUC. All the five performance indicators of the single-image input model were higher than those of the other model. The single-image input processing network, combining multiphase CTA images, can better classify AIS collateral circulation. This automated collateral assessment tool could help to streamline clinical workflows, and screen patients for reperfusion therapy.

Factors affecting mechanical thrombectomy outcome in acute ischemic stroke patients: an Egyptian sample

Background

Stroke constitutes a major health problem worldwide, nowadays endovascular treatment is considered to be a standard of care in acute ischemic stroke patients with large vessel occlusion, accurate prediction of outcome of thrombectomy is essential for health care providers, patients and families. We studied different clinical and radiological variables that could predict functional outcome in stroke patients after thrombectomy. Thirty-four consecutive ischemic stroke patients were included, received intravenous tissue plasminogen activator (iv-tpa), then mechanical thrombectomy was done. Patients were clinically assessed at admission with National Institute of Health Stroke Scale (NIHSS) then evaluated by the Alberta Stroke Program early computerized tomography (CT) score (ASPECTS), clot burden scale (CBS) and collateral score (CS) in multiphase computerized tomography angiography (CTA) then good and poor outcomes at 3 months were defined by Modified Rankin Scale (MRS) of 0–2 and 3–6 points, respectively.

Results

Factors associated with good outcome (MRS 0–2) were lower admission NIHSS score (p < 0.037), small infarct core aspects ≥ 6 (p < 0.001), low clot burden (CBS 7–10) (p = 0.046) good collaterals (2–3) (p = 0.038) and absence of post-procedure hemorrhage (p < 0.0005).

Conclusions

Low admission NIHSS score, absence of post-procedure hemorrhage, small infarct core, low clot burden and good collaterals are reliable factors for good clinical outcome.

Perfusion profile evaluated by severity-weighted multiple Tmax strata predicts early neurological deterioration in minor stroke with large vessel occlusion

Minor stroke due to large vessel occlusion (LVO) is associated with poor outcomes. Hypoperfused tissue fate may be more accurately predicted by severity-weighted multiple perfusion strata than by a single perfusion threshold. We investigated whether poor perfusion profile evaluated by multiple Tmax strata is associated with early neurological deterioration (END) in patients with minor stroke with LVO. Ninety-four patients with a baseline National Institute of Health Stroke Scale score ≤5 and anterior circulation LVO admitted within 24 hours of onset were included. Tmax strata proportions (Tmax 2-4 s, 4-6 s, 6-8 s, 8-10 s, and >10 s) against the entire hypoperfusion volume (Tmax >2 s) were measured. The perfusion profile was defined as the shift of the distribution of the Tmax strata proportions towards worse hypoperfusion severity compared with that of the entire cohort using the Wilcoxon-Mann-Whitney generalised odds ratio (OR); its performance to predict END was tested. The area under the curve of perfusion profile was 0.785 (95% confidence interval [CI]: 0.691-0.878, p < 0.001). Poor perfusion profile (generalised OR >1.052) was independently associated with END (adjusted OR 13.42 [95% CI: 4.38-41.15], p < 0.001). Thus, perfusion profile with severity-weighted multiple Tmax strata may predict END in minor stroke and LVO.

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.

Assessment of Collaterals Using Multiphasic CT Angiography in Acute Stroke: Its Correlation with Clinical Outcomes

Background and Purpose

The aim of the research was to compare the efficiency of multiphase and single-phase computed tomography (CT) angiography in assessing the leptomeningeal collaterals and in predicting the long-term clinical outcome as well as the risk of hemorrhagic transformation.

Materials and Methods

A prospective study was conducted from October 2016 to May 2018 in consecutive patients who presented within 8 hours of the onset of acute anterior circulation ischemic strokes, with NIHSS (National Institutes of Health Stroke Scale) scores ≥5. They underwent triple-phase cerebral CT angiography, and the collaterals were assessed separately using both single-phase and multiphase techniques. The ability of the collaterals to predict the 24-hour CT ASPECTS (Alberta Stroke Program Early CT score), risk of cerebral hemorrhagic transformation, and 90-day clinical outcome was assessed.

Results

Fifty-six patients, which included 42 with an involvement of the middle cerebral artery and 14 with mixed occlusions, were assessed. In the multivariate logistic analysis, multiphase CT angiography collateral grading is one of the independent predictors of favorable outcomes. Area under the curve (AUC) was 0.853 (95% confidence interval [CI; 0.73, 0.97]) for multiphase CT collateral scoring in predicting the long-term functional independence, whereas single-phase CT (sCT) scoring displayed an AUC value of only 0.609 (95% CI [0.43, 0.78]). Eighty-two percent of the patients with good multiphase CT collaterals were functionally independent. CT ASPECTS at 24 hours was significantly better in patients with a good multiphase CT collateral score than in those with a good single-phase score. None of the patients with good collaterals in multiphase CT angiography had a significant hemorrhagic transformation. Good multiphase CT collaterals demonstrated 78% sensitivity, 81% specificity, and 80% accuracy in predicting the functional outcome.

Conclusion

Multiphase CT collateral system was superior to single-phase angiography in predicting the long-term functional outcomes. Prediction of the hemorrhagic transformation risk was also observed to be better for multiphase CT.

Association Between CT Angiogram Collaterals and CT Perfusion in Delayed Time Windows for Large Vessel Occlusion Ischemic Strokes

OBJECTIVES

Recent endovascular trials have established the use of CT perfusion (CTP) in endovascular treatment selection for patients with large vessel occlusions (LVO). However, the relationship between CTP and collateral circulation is unclear in delayed time windows. We explored the relationship between CT Angiogram (CTA) collaterals and CTP parameters in delayed time windows (6-24 hours).

MATERIALS AND METHODS

We utilized a single institutional, retrospective stroke registry of consecutive patients between May 2016 and May 2018 with anterior LVO with CTA and CTP imaging within 6-24 hours of stroke onset. We graded baseline collaterals on single phase CTA using modified Tan collateral score (0-3) and dichotomized into good (2-3) and poor (0-1) collaterals. We recorded automated CTP parameters, including estimated ischemic core (cerebral blood flow (CBF)<30%), penumbra (T_max>6 s), and mismatch ratio. We used Mann-Whitney test and linear regression to assess associations.

RESULTS

We included 48 patients with median age of 62 years (IQR= 52-72), median core of 17.5 mL (IQR=0-47), and median penumbra of 117.5 mL (IQR= 62-163.5). Patients with good collaterals had smaller median core (0 mL, IQR=0-12 mL vs. 40.5 mL, IQR=15-60 mL) (p < 0.001), smaller median penumbra (83.5 mL, IQR=43-135 mL vs. 142.5 mL, IQR=77-190 mL) (p = 0.04), larger median mismatch ratio (13.7, IQR=5.7-58.0 vs. 3.1, IQR=2.1-5.0) (p < 0.001), and lower median hypoperfusion intensity ratio (0.23, IQR=0-0.44 vs. 0.52, IQR=0.45-0.63) (p < 0.001) than patients with poor collaterals.

CONCLUSIONS

In delayed time window LVO patients, good CTA collaterals are significantly associated with smaller CTP core, smaller penumbra, larger mismatch ratio, and lower hypoperfusion intensity ratio. CTA collateral assessment could be a potential valuable surrogate to perfusion imaging, particularly in stroke centers where CTP is unavailable.

Safety and Efficacy of Endovascular Treatment for Progressive Stroke in Patients With Acute Basilar Artery Occlusion

Background and Purpose: It is unknown the benefit of endovascular therapy (EVT) for progressive stroke in patients with basilar artery occlusion (BAO). The aim of this study was to compare the efficacy and safety of EVT with standard medical therapy (SMT) in a population of BAO patients with progressive stroke.

Methods: The EVT for Acute Basilar Artery Occlusion Study (BASILAR) is a national prospective registry of consecutive patients with acute BAO within 24 h of symptom onset. According to the applied therapy, all patients were divided into SMT and EVT groups. Subsequently, the EVT group was divided into early (≤6 h) and late groups (>6 h) according to the time window. The efficacy outcome was favorable functional outcomes (modified Rankin Scale score ≤ 3) at 90 days. The safety outcomes included mortality within 90 days and symptomatic intracerebral hemorrhage (sICH) after EVT.

Results: The EVT cohort presented more frequently with a favorable functional outcome (adjusted odds ratio, 5.49; 95% confidence interval, 2.06–14.61, p = 0.01) and with a decreased mortality (adjusted odds ratio, 0.3; 95% confidence interval, 0.17–0.54, p < 0.001). What's more, EVT still safe (P = 0.584, P = 0.492, respectively) and effective (P = 0.05) in patients with progressive stroke when the treatment time window exceeds 6 h.

Conclusions: EVT was more effective and safer than SMT for progressive stroke in patients with BAO. Besides, EVT remains safe and effective in patients with progressive stroke when the treatment time window exceeds 6 h. Predictors of desirable outcome in progressive stroke patients undergoing EVT included lower baseline NIHSS score, higher baseline pc-ASPECTs, successful recanalization and shorter puncture to recanalization time.

Value of pre-intervention CT perfusion imaging in acute ischemic stroke prognosis

Noninvasive imaging plays an important role in acute stroke towards diagnosis and ongoing management of patients. Systemic thrombolysis and endovascular thrombectomy (EVT) are proven treatments currently used in standards of care in acute stroke settings. The role of computed tomography angiography (CTA) in selecting patients with large vessel occlusion for EVT is well established. However, the value of CT perfusion (CTP) imaging in predicting outcomes after stroke remains ambiguous. This article critically evaluates the value of multimodal CT imaging in early diagnosis and prognosis of acute ischemic stroke with a focus on the role of CTP in delineating tissue characteristics, patient selection, and outcomes after reperfusion therapy. Insights on various technical and clinical considerations relevant to CTP applications in acute ischemic stroke, recommendations for existing workflow, and future areas of research are discussed.

Time-Based Decision Making for Reperfusion in Acute Ischemic Stroke

Decision making in the extended time windows for acute ischemic stroke can be a complex and time-consuming process. The process of making the clinical decision to treat has been compounded by the availability of different imaging modalities. In the setting of acute ischemic stroke, time is of the essence and chances of a good outcome diminish by each passing minute. Navigating the plethora of advanced imaging modalities means that treatment in some cases can be inefficaciously delayed. Time delays and individually based non-programmed decision making can prove challenging for clinicians. Visual aids can assist such decision making aimed at simplifying the use of advanced imaging. Flow charts are one such visual tool that can expedite treatment in this setting. A systematic review of existing literature around imaging modalities based on site of occlusion and time from onset can be used to aid decision making; a more program-based thought process. The use of an acute reperfusion flow chart helping navigate the myriad of imaging modalities can aid the effective treatment of patients.

State of the Art Stroke Imaging: A Current Perspective

Acute stroke is a widespread, debilitating disease. Fortunately, it also has one of the most effective therapeutic options available in medicine, endovascular treatment. Imaging plays a major role in the diagnosis of stroke and aids in appropriate therapy selection. Given the rapid accumulation of evidence for patient subgroups and concurrent broadening of therapeutic options and indications, it is important to recognize the benefits of certain imaging technologies for specific situations. An effective imaging protocol should: 1) be fast, 2) easily implementable, 3) produce reliable results, 4) have few contraindications, and 5) be safe, all with the goal of providing the patient the best chance of achieving a favorable outcome. In the following, we provide a review of the currently available imaging technologies, their advantages and disadvantages, as well as an overview of the future of stroke imaging. Finally, we offer a perspective.

Effects of Anterior Borderzone Angle Grading on Predicting the 90-Day Prognosis After Recanalization of Acute Middle Cerebral Artery Occlusion

Objective: This work explores collateral circulation metrics, such as the anterior borderzone angle grading (ABZA-grading), as a predictor of the prognosis in patients with acute middle cerebral artery occlusion (MCAO) following endovascular treatment (EVT).

Methods: Clinical data from 108 patients with acute MCAO, treated by EVT, were retrospectively analyzed. In patients with MCAO, ABZA is the angle between the median line of the sagittal sinus and the borderzone of the pial arterioles of ACA and MCA, and the ABZA/23.0° was rounded to obtain the corresponding collateral circulation score (ABZA-grading). In parallel, the primary outcome was defined as the 90-day clinical outcome by modified ranking scale score (mRS). Univariate analysis and logistic regression were used to analyze the independent predictors of the 90-day clinical outcome (mRS). Receiver operating characteristic curve (ROC) analysis was used to judge the predictive value of ABZA.

Results: Univariate analysis and logistic regression analysis showed that ABZA-grading > 2 and age were independent predictors of the 90-day clinical outcome after EVT in patients with acute MCAO. The ROC analysis showed that ABZA alone could predict a favorable 90-day clinical outcome with an area under the curve (AUC) of 0.868. Using an ABZA of >57.8° (the corresponding ABZA-grading of >2) as the cut-off value, the predictive sensitivity and specificity were 75.7 and 88.7%, respectively. Contingency table analysis showed a statistical difference in mRS score between ABZA-grading subgroups, and ABZA-grading between stroke caused by large artery atherosclerosis (LAA) and cardiogenic embolism (CE).

Conclusion: The ABZA-grading is an easy and objective assessment of collateral circulation that is independently associated with short-time clinical outcome after EVT in patients with acute MCAO. Therefore, it may guide selection of patients with acute ischemic stroke (AIS) suitable for EVT. The ABZA-grading of collateral circulation can be a supplemental metric to help differentiate stroke by LAA and CE.

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.

Course of Early Neurologic Symptom Severity after Endovascular Treatment of Anterior Circulation Large Vessel Occlusion Stroke: Association with Baseline Multiparametric CT Imaging and Clinical Parameters

Background: Neurologic symptom severity and deterioration at 24 hours (h) predict long-term outcomes in patients with acute large vessel occlusion (LVO) stroke of the anterior circulation. We aimed to examine the association of baseline multiparametric CT imaging and clinical factors with the course of neurologic symptom severity in the first 24 h after endovascular treatment (EVT). Methods: Patients with LVO stroke of the anterior circulation were selected from a prospectively acquired consecutive cohort of patients who underwent multiparametric CT, including non-contrast CT, CT angiography and CT perfusion before EVT. The symptom severity was assessed on admission and after 24 h using the 42-point National Institutes of Health Stroke Scale (NIHSS). Clinical and imaging data were compared between patients with and without early neurological deterioration (END). END was defined as an increase in ≥4 points, and a significant clinical improvement as a decrease in ≥4 points, compared to NIHSS on admission. Multivariate regression analyses were used to determine independent associations of imaging and clinical parameters with NIHSS score increase or decrease in the first 24 h. Results: A total of 211 patients were included, of whom 38 (18.0%) had an END. END was significantly associated with occlusion of the internal carotid artery (odds ratio (OR), 4.25; 95% CI, 1.90–9.47) and the carotid T (OR, 6.34; 95% CI, 2.56–15.71), clot burden score (OR, 0.79; 95% CI, 0.68–0.92) and total ischemic volume (OR, 1.01; 95% CI, 1.00–1.01). In a comprehensive multivariate analysis model including periprocedural parameters and complications after EVT, carotid T occlusion remained independently associated with END, next to reperfusion status and intracranial hemorrhage. Favorable reperfusion status and small ischemic core volume were associated with clinical improvement after 24 h. Conclusions: The use of imaging parameters as a surrogate for early NIHSS progression in an acute LVO stroke after EVT reached limited performance with only carotid T occlusion as an independent predictor of END. Reperfusion status and early complications in terms of intracranial hemorrhage are critical factors that influence patient outcome in the acute stroke phase after EVT.

Hypoperfusion intensity ratio for refinement of elderly patient selection for endovascular thrombectomy

BACKGROUND

Patients ≥80-year-old presenting with large-vessel occlusion treated with endovascular thrombectomy (EVT) have worst outcomes than younger individuals. Improved patient selection in this age range is warranted. We investigated the hypoperfusion-intensity-ratio (HIR) and its associations with baseline parameters and clinical outcomes in a cohort ≥80-year-old to assess whether it could an option in improving their selection for EVT.

METHODS

We performed retrospective analysis of consecutive patients treated with EVT at our center between 2015 and 2019. Inclusion criteria were age ≥80-year-old, any baseline modified Rankin Scale (mRS), and anterior circulation occlusion. Demographic information, baseline characteristics, clinical data, and radiological imaging parameters were collected. HIR was dichotomized into favorable and unfavorable based on median value of the cohort. Good outcome was defined as mRS ≤2 at 90-days.

RESULTS

We included 82 patients. HIR was significantly correlated with baseline ischemic core volume, NIHSS, and time-of-onset to groin puncture. Good outcome was achieved in 18.3% and mortality occurred in 34.1%. In patients with baseline mRS ≤2, the rate of good outcome was significantly higher in favorable vs unfavorable HIR (52.6% vs 20%, P=0.02). In shift-analysis, unfavorable HIR was significantly associated with downshift to mRS ≥3 (P=0.02). Regression analysis found lower baseline mRS (P=0.009), higher ASPECTS (P=0.02), complete recanalization (P=0.04), and lower HIR (P=0.02) to be associated with increased rate of good outcome. Hierarchical regression showed HIR to independently predict good outcome.

CONCLUSIONS

In our cohort, HIR was correlated with baseline parameters and predicted clinical outcomes. Future studies should investigate perfusion parameters such as HIR to improve the selection of elderly patients for EVT.

Decomposing Acute Symptom Severity in Large Vessel Occlusion Stroke: Association With Multiparametric CT Imaging and Clinical Parameters

Background and Purpose: Acute ischemic stroke of the anterior circulation due to large vessel occlusion (LVO) is a multifactorial process, which causes neurologic symptoms of different degree. Our aim was to examine the impact of neuromorphologic and vascular correlates as well as clinical factors on acute symptom severity in LVO stroke. Methods: We selected LVO stroke patients with known onset time from a consecutive cohort which underwent multiparametric CT including non-contrast CT, CT angiography and CT perfusion (CTP) before thrombectomy. Software-based quantification was used to calculate CTP total ischemic and ischemic core volume. Symptom severity was assessed using the National Institutes of Health Stroke Scale (NIHSS) upon admission. Multivariable regression analysis was performed to determine independent associations of admission NIHSS with imaging and clinical parameters. Receiver operating characteristics (ROC) analyses were used to examine performance of imaging parameters to classify symptom severity. Results: We included 142 patients. Linear and ordinal regression analyses for NIHSS and NIHSS severity groups identified significant associations for total ischemic volume [β = 0.31, p = 0.01; Odds ratio (OR) = 1.11, 95%-confidence-interval (CI): 1.02-1.19], clot burden score (β = -0.28, p = 0.01; OR = 0.76, 95%-CI: 0.64-0.90) and age (β = 0.17, p = 0.04). No association was found for ischemic core volume, stroke side, collaterals and time from onset. Stroke topography according to the Alberta Stroke Program CT Score template did not display significant influence after correction for multiple comparisons. AUC for classification of the NIHSS threshold ≥6 by total ischemic volume was 0.81 (p < 0.001). Conclusions: We determined total ischemic volume, clot burden and age as relevant drivers for baseline NIHSS in acute LVO stroke. This suggests that not only mere volume but also degree of occlusion influences symptom severity. Use of imaging parameters as surrogate for baseline NIHSS reached limited performance underlining the need for combined clinical and imaging assessment in acute stroke management.

Perfusion and Diffusion Variables Predict Early Neurological Deterioration in Minor Stroke and Large Vessel Occlusion

Background and Purpose

Patients with acute large vessel occlusion (LVO) presenting with mild stroke symptoms are at risk of early neurological deterioration (END). This study aimed to identify the optimal imaging variables for predicting END in this population.

Methods

We retrospectively analyzed 94 patients from the prospectively maintained institutional stroke registry admitted between January 2011 and May 2019, presenting within 24 hours after onset, with a baseline National Institutes of Health Stroke Scale score ≤5 and anterior circulation LVO. Patients who underwent endovascular therapy before END were excluded. Volumes of Tmax delay (at >2, >4, >6, >8, and >10 seconds), mismatch (Tmax >4 seconds – diffusion-weighted imaging [DWI] and Tmax >6 seconds – DWI), and mild hypoperfusion lesions (Tmax 2–6 and 4–6 seconds) were measured. The association of each variable with END was examined using receiver operating characteristic curves. The variables with best predictive performance were dichotomized at the cutoff point maximizing Youden’s index and subsequently analyzed using multivariable logistic regression.

Results

END occurred in 39.4% of the participants. The optimal variables were identified as Tmax >6 seconds, Tmax >6 seconds – DWI, and Tmax 4–6 seconds with cut-off points of 53.73, 32.77, and 55.20 mL, respectively. These variables were independently associated with END (adjusted odds ratio [aOR], 12.78 [95% confidence interval (CI), 3.36 to 48.65]; aOR, 5.73 [95% CI, 2.04 to 16.08]; and aOR, 9.13 [95% CI, 2.76 to 30.17], respectively).

Conclusions

Tmax >6 seconds, Tmax >6 seconds – DWI, and Tmax 4–6 seconds could identify patients at high risk of END following minor stroke due to LVO.

Head and neck CT angiography to assess the internal carotid artery stealing pathway

Background

Common carotid artery occlusive disease (CCAOD) could form internal carotid artery steal pathways. Based on the diagnostic results of digital subtraction angiography (DSA), head and neck computed tomography angiography (CTA) was used to find the internal carotid artery stealing pathway after CCAOD.

Methods: The clinical and imaging data of 18 patients with CCAOD were retrospectively analyzed. DSA and CTA was used to evaluate internal carotid artery steal pathways.

Results

Of the 18 patients with CCAOD, 10 patients found internal carotid artery steal pathways. There were 7 males and 3 females. Vascular ultrasound examination of all patients: The affected side had no blood flow in common carotid artery (CCA), and had retrograde blood flow in the external carotid artery (ECA). The blood flow of the affected side was decreased in the internal carotid artery (ICA), but it was antegrade. DSA diagnosed 10 cases of CCA occlusion and CTA diagnosed 10 cases of CCA occlusion. DSA and CTA found 6 internal carotid artery blood stealing pathways: ① Vertebral artery → occipital artery → external carotid artery → internal carotid artery (6 cases); ② Thyrocervical trunk → ascending cervical artery → occipital artery → external carotid artery → internal carotid artery (7 cases); ③ Costocervical trunk → deep cervical artery → occipital artery → external carotid artery → internal carotid artery (6 cases); ④ Affected side thyroid neck trunk → inferior thyroid artery → superior thyroid artery → external carotid artery → internal carotid artery (2 cases); ⑤ Contralateral external carotid artery → contralateral superior thyroid artery → affected superior thyroid artery → external carotid artery → neck Internal artery (2 cases); ⑥ Parathyroid neck → superficial cervical artery → occipital artery → external carotid artery → internal carotid artery (1 case).

Conclusions

The patients with CCAOD can find the internal carotid artery blood stealing pathway through CTA.

Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis

In patients with carotid artery stenosis (CAS), the risk of stroke, its severity, and response to revascularization are strongly related to the availability of collateral blood flow. Unfortunately, there is poor agreement between observers in assessing collateral flow using flow-based imaging. We used changes in blood-oxygen-level-dependent (BOLD) MRI as a surrogate of changes in regional cerebral blood flow in response to a hypercapnic stimulus [i.e., cerebrovascular reactivity (CVR)] as indicating flow reserve ipsilateral to CAS. We hypothesized that some patients with hemodynamically significant CAS develop functional collateral flow as indicated by normalization of ipsilateral CVR. We identified 55 patients in our CVR database with various degrees of CAS assessed by angiography and classed them as <50% stenosis, 50–69% stenosis, 70–90% stenosis, >90% stenosis, and full occlusion. CVR was measured as the change in BOLD signal in response to changes in end-tidal partial pressure of CO₂ (Δ BOLD/Δ PETCO₂) and normalized voxel-wise relative to the mean and standard deviation of the CVR in the corresponding voxels of an atlas of 46 healthy controls (CVR z scores). CVR and z scores were then averaged over gray matter (GM) and white matter (WM) on each side of the middle cerebral artery (MCA) territory. As hypothesized, CVR varied for each severity of CAS. Ipsilateral MCA territory CVR was less than normal in each class, including that with <50% stenosis (Student t-test, two-tailed; p = 0.0014 for GM and p = 0.030 for WM), with a trend of decreasing average CVR with increasing stenosis. Remarkably, the considerable individual variability in MCA CVR included some patients with normal CVR in each class – including that with complete occlusion. We conclude that, in general, CAS depresses downstream vascular reserve, but the extent of collateralization is highly variable and not predictable from the degree of stenosis, including both <50% stenosis and complete occlusion. CVR may be the more reliable marker for recruitable collateral blood flow than degree of CAS.

Effects of Collateral Status on Infarct Distribution Following Endovascular Therapy in Large Vessel Occlusion Stroke

BACKGROUND AND PURPOSE

We aim to examine effects of collateral status and post-thrombectomy reperfusion on final infarct distribution and early functional outcome in patients with anterior circulation large vessel occlusion ischemic stroke.

METHODS

Patients with large vessel occlusion who underwent endovascular intervention were included in this study. All patients had baseline computed tomography angiography and follow-up magnetic resonance imaging. Collateral status was graded according to the criteria proposed by Miteff et al and reperfusion was assessed using the modified Thrombolysis in Cerebral Infarction (mTICI) system. We applied a multivariate voxel-wise general linear model to correlate the distribution of final infarction with collateral status and degree of reperfusion. Early favorable outcome was defined as a discharge modified Rankin Scale score ≤2.

RESULTS

Of the 283 patients included, 129 (46%) had good, 97 (34%) had moderate, and 57 (20%) had poor collateral status. Successful reperfusion (mTICI 2b/3) was achieved in 206 (73%) patients. Poor collateral status was associated with infarction of middle cerebral artery border zones, whereas worse reperfusion (mTICI scores 0-2a) was associated with infarction of middle cerebral artery territory deep white matter tracts and the posterior limb of the internal capsule. In multivariate regression models, both mTICI (P<0.001) and collateral status (P<0.001) were among independent predictors of final infarct volumes. However, mTICI (P<0.001), but not collateral status (P=0.058), predicted favorable outcome at discharge.

CONCLUSIONS

In this cohort of patients with large vessel occlusion stroke, both the collateral status and endovascular reperfusion were strongly associated with middle cerebral artery territory final infarct volumes. Our findings suggesting that baseline collateral status predominantly affected middle cerebral artery border zones infarction, whereas higher mTICI preserved deep white matter and internal capsule from infarction; may explain why reperfusion success-but not collateral status-was among the independent predictors of favorable outcome at discharge. Infarction of the lentiform nuclei was observed regardless of collateral status or reperfusion success.

Acute Neurological Deterioration in Large Vessel Occlusions and Mild Symptoms Managed Medically

Background and Purpose—

It is unclear which factors predict acute neurological deterioration in patients with large vessel occlusion and mild symptoms. We aim to evaluate the frequency, timing, and potential predictors of acute neurological deterioration ≥4 National Institutes of Health Stroke Scale (NIHSS) points in medically managed patients with large vessel occlusion and mild presentation.

Methods—

Single-center retrospective study of patients with consecutive minor stroke (defined as NIHSS score of ≤5 on presentation) and large vessel occlusion from January 2014 to December 2017. Primary outcome was acute neurological deterioration ≥4 NIHSS points during the hospitalization. Secondary outcomes included ΔNIHSS (defined as discharge minus admission NIHSS score).

Results—

Among 1133 patients with acute minor strokes, 122 (10.6%) had visible occlusions on computed tomography angiography/magnetic resonance angiography. Twenty-four (19.7%) patients had ≥4 points deterioration on NIHSS at a median of 3.6 (1–16) hours from arrival. No clinical or radiological predictors of acute neurological deterioration ≥4 NIHSS points were observed on multivariable analysis. Rescue endovascular thrombectomy was performed more often in the ones with acute neurological deterioration ≥4 NIHSS points compared with patients with no deterioration (54% versus 0%; P <0.001). Acute neurological deterioration ≥4 NIHSS points was associated with ΔNIHSS ≥4 points (33% versus 4.9%; P <0.01) and a trend toward lower independence rates at discharge (50% versus 70%; P =0.06) compared with the group with no deterioration. In patients with any degree of neurological worsening, patients who underwent rescue thrombectomy were more likely to be independent at discharge (73% versus 38%; P =0.02) and to have a favorable ΔNIHSS (−2 [−3 to 0] versus 0 [−1 to 6]; P =0.05) compared with the ones not offered rescue thrombectomy.

Conclusions—

Acute neurological deterioration ≥4 NIHSS points was observed in a fifth of patients with large vessel occlusion and mild symptoms, occurred very early in the hospital course, impacted functional outcomes, and could not be predicted by any of the studied clinical and radiological variables. Rescue thrombectomy was associated with improved clinical outcomes at discharge in patients with neurological deterioration.

Evaluation of Intracranial Vascular Status in Patients with Acute Ischemic Stroke by Time Maximum Intensity Projection CT Angiography: A Preliminary Study

RATIONALE AND OBJECTIVES

To describe the application of time maximum intensity projection CTA (t-MIP CTA) in acute ischemic stroke and compare t-MIP CTA and single-phase CTA (sCTA) in assessing collateral circulation and predicting prognosis.

MATERIALS AND METHODS

Twenty-nine acute ischemic stroke patients who underwent one-stop CT angiography (CTA)-CT perfusion scan were reviewed retrospectively. sCTA and t-MIP CTA were developed by CT perfusion scanning data. Image quality and collateral circulation were compared between the sCTA and t-MIP CTA groups. CT attenuation values, image noise, signal to noise , contrast to noise, and subjective image quality were obtained and compared between these two groups. The correlations of clinical prognosis and infarct volume with collateral status on t-MIP CTA and sCTA were analyzed, separately. Receiver operating characteristic curve was used to reveal the sensitivity and specificity of t-MIP CTA and sCTA in predicting outcome.

RESULTS

All images exhibited good quality for diagnosis. In objective evaluation, the noise level of t-MIP CTA was significantly lower than that of sCTA (p < 0.001). Vascular attenuation (signal to noise and contrast to noise) of t-MIP were higher than those of sCTA (all, p < 0.001). The collateral status on t-MIP CTA and sCTA were both negatively correlated with modified Rankin Scale scores (t-MIP CTA, r = -0.709, p < 0.001; sCTA, r = -0.551, p = 0.024) and the final infarction volume (t-MIP CTA, r = -0.716, p = 0.001; sCTA, r = -0.629, p = 0.003). t-MIP CTA was better for predicting prognosis (AUC, 0.956; sensitivity, 0.917; specificity, 0.941; p < 0.001) than sCTA (AUC, 0.824; sensitivity, 0.500; specificity, 0.941; p = 0.003).

CONCLUSION

In comparison with sCTA, t-MIP images showed higher image quality of intracranial vascularity and MIP could reveal vascular occlusion and evaluate collateral circulation more accurately. It was speculated that t-MIP could predict the prognosis more precisely.

Radiological predictors of hemorrhagic transformation after acute ischemic stroke: An evidence-based analysis

Hemorrhagic transformation (HT) is one of the most common adverse events related to acute ischemic stroke (AIS) that affects the treatment plan and clinical outcome. Identification of a sensitive radiological marker may influence the controversial thrombolytic decision in the setting of AIS and may at a minimum indicate more intensive monitoring or further prophylactic interventions. In this article we summarize possible radiological biomarkers and the role of different radiological modalities including computed tomography (CT), magnetic resonance imaging, angiography, and ultrasound in predicting HT. Different radiological indices of early ischemic changes, large ischemic lesion volume, severe blood flow restriction, blood-brain barrier disruption, poor collaterals and high blood flow velocities have been reported to be associated with higher risk of HT. The current levels of evidence of the available studies highlight the role of the different CT perfusion parameters in predicting HT. Further large standardized studies are recommended to compare the sensitivity and specificity of the different radiological markers combined and delineate the most reliable predictor.

Demographic age-related variation in Circle of Willis completeness assessed by digital subtraction angiography

OBJECTIVE:

Incomplete circle of Willis (CoW) configuration is an important risk factor for cerebrovascular pathology, namely aneurysm formation and ischemic stroke. This study was performed to characterize CoW variation using digital subtraction angiography and to identify demographic and physiologic features that may influence the risk of having an incomplete CoW configuration.

MATERIALS AND METHODS:

A retrospective review of 274 patients who underwent cerebral angiography by a single surgeon for any indication was conducted. Each CoW branch was graded as normal, hypoplastic, or aplastic. Univariate and multivariate regression analyses were conducted to assess the impact of age, gender, race, and certain comorbidities on CoW configuration.

RESULTS:

A complete CoW was identified in 37.23% of patients. In univariate analysis, patients <40 years old were more likely to have a complete CoW (odds ratio [OR]: 4.973, 95% confidence interval [CI]: 2.610–9.476, P < 0.001) as were patients <70 years old (OR: 2.849, 95% CI: 1.131–7.194, P < 0.05). Univariate analysis on demographic factors and comorbidities revealed CoW completeness to decrease with hypertension (OR: 0.575, 95% CI: 0.347–0.951, P = 0.031) and diabetes mellitus (OR: 0.368, 95% CI: 0.180–0.754, P = 0.006). Multivariable logistic regression analysis used to assess the impact of age on CoW completeness showed age to be an independent predictor of complete CoW, with an inverse correlation between increasing age and CoW completeness (OR: 0.955, 95% CI: 0.937–0.973, P < 0.001) after controlling for potential confounders including hypertension and diabetes mellitus.

CONCLUSIONS:

CoW configuration shows considerable variation with age; however, further investigation is required to elucidate the full impact of other demographic and vascular risk factors on CoW anatomy.

Clinical characteristics and leptomeningeal collateral status in pediatric and adult patients with ischemic moyamoya disease

AIM

Previous studies have found significant differences in clinical characteristics between pediatric and adult moyamoya disease (MMD) patients, but few studies have focused on the factors underlying these differences. We aimed to investigate the differences in leptomeningeal collateral (LMC) status between pediatric and adult MMD patients and to analyze the effects of LMCs on clinical characteristics and therapeutic prognosis.

METHODS

We retrospectively analyzed 214 MMD patients from January 2014 to January 2016. Clinical characteristics and LMC status were compared between the pediatric and adult patients. LMC status was graded as good or poor depending on the retrograde flow from the posterior cerebral artery (PCA) on digital subtraction angiography (DSA).

RESULTS

A total of 83 pediatric and 131 adult (1:1.6) MMD patients were analyzed. Pediatric patients were more likely to experience a transient ischemic attack (81%), whereas adult patients were more likely to experience infarction (51%). Regarding the different MMD stages (the early, medium, and advanced stages corresponded to Suzuki stages 1-2, 3-4, and 5-6, respectively), the prevalence of good LMC status was higher for pediatric patients than for adult patients in the early stage (P = 0.047) and the medium stage (P = 0.001), but there were no differences between these patient groups in the advanced stage (P = 0.547). Worse postoperative angiographic outcomes (P = 0.017) were found in adult patients than in pediatric patients in the medium stage. Poor LMC status had strong correlations with infarction (P < 0.001 and P = 0.017) and poor postoperative outcomes (P = 0.003 and P = 0.043) in both pediatric and adult patients.

CONCLUSIONS

Pediatric MMD patients have greater patency and a greater ability to establish good LMC status than adult patients, and poor LMC status has a strong correlation with severe clinical symptoms and poor postoperative outcomes. LMC status may be an important factor in the differences in clinical characteristics and prognosis between pediatric and adult MMD patients.

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.

Collateral Circulation in Moyamoya Disease: A New Grading System

Background and Purpose- Predicting the risk of stroke and determining intervention indications are highly important for patients with Moyamoya disease (MMD). Here, we evaluated a novel MMD grading system based on collateral circulation and Suzuki stage to evaluate symptoms and predict prognosis. Methods- In total, 301 idiopathic MMD patients were retrospectively analyzed between 2014 and 2016. A collateral circulation grading system with scores ranging from 1 to 12 was established: the anatomic extent of pial collateral blood flow from posterior cerebral artery to middle cerebral artery and anterior cerebral artery was scored from 1 to 6; perforator collateral and internal cerebral artery flow were scored as 6 to 1, which corresponded to Suzuki stages 1 to 6. Dynamic susceptibility contrast-magnetic resonance imaging was used to evaluate hemodynamic status. We assessed the association between the grading system and clinical characteristics. Results- We analyzed 364 symptomatic hemispheres of 301 patients (146 males, 28±16 years). Ischemic patients who presented with infarction were more likely to score <8 points (P<0.001), whereas those with ischemia symptoms (transient ischemic attack and headache) were more likely to score >8 points. Hemorrhagic patients who presented with intraparenchymal hemorrhage were more likely to score <8 points, whereas those who presented with intraventricular hemorrhage were more likely to score >8 points (P<0.001). According to dynamic susceptibility contrast-magnetic resonance imaging, lower scores were correlated with more severe time to peak delay (P<0.001) and worse relative cerebral blood volume ratio (P=0.016) and cerebral flow ratio (P=0.002). Encephaloduroarteriosynangiosis was performed in 348 symptomatic hemispheres. Patients who had collateral scores <4 points were more likely to have a postoperative stroke and a worse prognosis during the follow-up. Conclusions- This new MMD collateral grading system correlated well with clinical symptoms, hemodynamic status, and therapeutic prognosis and may facilitate risk stratification and prognosis predictions in patients with MMD.

[Collateral circulation and Toll-like receptor 4 levels in patients with acute cerebral infarction after intravenous thrombolysis]

OBJECTIVE

To investigate the relationship between Toll-like receptor 4 (TLR4) and collateral circulation in patients with acute cerebral infarction (AIS) after thrombolytic therapy.

METHODS

This retrospective, observational cohort study was conducted among 65 patients with AIS receiving thrombolytic therapy, who were divided according to findings by computed tomographic angiography (CTA) into good collateral circulation (group A, n = 34) and poor collateral circulation (group B, n = 31). Serum samples were collected from all the patients and the levels of TLR4 were measured with ELISA.

RESULTS

The patients in group A had significantly better outcomes than those in group B. The NIHSS scores at 24 h and 30 days after thrombolytic therapy, mRS scores at 90 days and serum TLR4 levels were significantly lower in group A than in group B (P &lt; 0.05); the percentages of patients with symptomatic intracerebral hemorrhage were comparable between the two groups. The serum levels of TLR4 were negatively correlated with the rMLC score (P &lt; 0.05). Multivariate logistic regression analysis showed that a high level of TLR4 was associated with a poor collateral circulation after thrombolysis.

CONCLUSIONS

Good collateral circulation can increase the benefit of intravenous thrombolysis in patients with ACI, and the level of TLR4 is a predictive factor for the compensation of collateral circulation following ACI.

Collaterals are a major determinant of the core but not the penumbra volume in acute ischemic stroke

PURPOSE

Determinants of early loss of ischemic tissue (core) or its prolonged survival (penumbra) in acute ischemic stroke (AIS) are poorly understood. We aimed to identify radiological associations of core and penumbra volumes on CT perfusion (CTP) in a large cohort of AIS.

METHODS

In the ASTRAL registry (2003-2016), we identified consecutive AIS patients with proximal middle cerebral artery (MCA) occlusion. We calculated core and penumbra volumes using established thresholds and the mismatch ratio (MR). We graded collaterals into three categories on CT-angiography. We used clot burden score (CBS) to quantify the clot length. We related CTP volumes to radiological variables in multivariate regression analyses, adjusted for time from stroke onset to first imaging.

RESULTS

The median age of the 415 included patients was 69 years (IQR = 21) and 49% were female. Median admission NIHSS was 16 (11) and median delay to imaging 2.2 h (1.9). Lower core volumes were associated with higher ASPECTS (hazard ratio = 1.08), absence of hyperdense MCA sign (HR = 0.70), higher CBS (i.e., smaller clot, HR = 1.10), and better collaterals (HR = 1.95). Higher penumbra volumes were related to lower CBS (i.e., longer clot, HR = 1.08) and proximal intracranial occlusion (HR = 1.47), but not to collaterals. Higher MR was found in absence of hyperdense MCA sign (HR = 1.28), absence of distal intracranial occlusion (HR = 1.39), and with better collaterals (HR = 0.52).

CONCLUSIONS

In AIS, better collaterals were associated with lower core volumes, but not with higher penumbra volumes. This suggests a major role of collaterals in early tissue loss and their limited significance as marker of salvageable tissue.

Factors influencing infarct growth including collateral status assessed using computed tomography in acute stroke patients with large artery occlusion

In major ischemic stroke caused by a large artery occlusion, neuronal loss varies considerably across individuals without revascularization. This study aims to identify which patient characteristics are most highly associated with this variability. Demographic and clinical information were retrospectively collected on a registry of 878 patients. Imaging biomarkers including Alberta Stroke Program Early CT score, noncontrast head computed tomography infarct volume, perfusion computed tomography infarct core and penumbra, occlusion site, collateral score, and recanalization status were evaluated on the baseline and early follow-up computed tomography images. Infarct growth rates were calculated by dividing infarct volumes by the time elapsed between the computed tomography scan and the symptom onset. Collateral score was graded into four levels (0, 1, 2, and 3) in comparison with the normal side. Correlation of perfusion computed tomography and noncontrast head computed tomography infarct volumes and infarct growth rates were estimated with the nonparametric Spearman's rank correlation. Conditional inference trees were used to identify the clinical and imaging biomarkers that were most highly associated with the infarct growth rate and modified Rankin Scale at 90 days. Two hundred and thirty-two patients met the inclusion criteria for this study. The median infarct growth rates for perfusion computed tomography and noncontrast head computed tomography were 11.2 and 6.2 ml/log(min) in logarithmic model, and 18.9 and 10.4 ml/h in linear model, respectively. Noncontrast head computed tomography and perfusion computed tomography infarct volumes and infarct growth rates were significantly correlated (rho=0.53; P < 0.001). Collateral status was the strongest predictor for infarct growth rates. For collateral=0, the perfusion computed tomography and noncontrast head computed tomography infarct growth rate were 31.56 and 16.86 ml/log(min), respectively. Patients who had collateral >0 and penumbra volumes>92 ml had the lowest predicted perfusion computed tomography infarct growth rates (6.61 ml/log(min)). Collateral status was closely related to the diversity of infarct growth rates, poor collaterals were associated with a faster infarct growth rates and vice versa.