Systematic comparison of perfusion-CT and CT-angiography in acute stroke patients

Circle of Willis integrity in acute middle cerebral artery occlusion: does the posterior communicating artery matter?

BACKGROUND

Collateral circulation is an important determinant of outcome in people with acute ischemic stroke due to large vessel occlusion (LVO).

OBJECTIVE

To explore the impact of the circle of Willis (CW) anatomical characteristics ipsilateral to the occlusion site, particularly the posterior communicating artery (PComA) and the A1-portion of the anterior cerebral artery (A1-ACA), on stroke outcomes in a cohort of patients with LVO and middle cerebral artery (MCA) occlusion, undergoing endovascular thrombectomy (EVT).

METHODS

This is a retrospective cohort study performed in a comprehensive tertiary stroke center. The study population consisted of consecutive patients with LVO with proximal MCA occlusion (M1) between June 2016 and April 2021, undergoing EVT. Demographic, clinical, and imaging information was extracted from patient files. Patency and diameters of ipsilateral A1-ACA and PComA were manually measured on admission CT angiography images in the core laboratory.

RESULTS

One hundred and five patients with LVO comprised the study cohort, mean age 72.3 years, 43.8% were male, mean National Institutes of Health Stroke Scale score at admission 15.2. The cohort was grouped according to CW vessel characteristics. On univariate analysis, a well-developed PComA was associated with lower rates of hemorrhagic transformation (1.8% vs 14.3%, P=0.01) and a trend towards lower mortality rates (8.9% vs 20.4%, P=0.08).On multivariable regression analysis a well-developed PComA emerged as an independent predictor for survival (aOR=0.09, 95% CI 0.01 to 0.4 for survival at discharge, P=0.009, aOR=0.22, 95% CI 0.05 to 0.8 for survival at 90 days, P=0.02).

CONCLUSIONS

In a cohort of patients with LVO due to M1 occlusion undergoing EVT, a well-developed PComA was associated with significantly lower hemorrhagic transformation rates, a trend towards better functional outcomes, and independently predicted survival. Larger studies are needed to understand the differential effect of CW collateral conduits on stroke outcome and evaluate the practicality of incorporating such factors in the clinical decision-making process prior to EVT.

Hypoperfusion Intensity Ratio Is Associated with Early Neurologic Deficit Severity and Deterioration after Mechanical Thrombectomy in Large-Vessel Occlusion Ischemic Stroke

BACKGROUND AND PURPOSE

The hypoperfusion intensity ratio is a surrogate marker for collateral status and a predictor of infarct growth, malignant cerebral edema, and hemorrhagic transformation. Its utility to predict a poor NIHSS score and early neurologic deterioration after mechanical thrombectomy for large vessel (LVO) versus distal and medium vessel occlusions (DMVO) has not been investigated. The objective of this study was to determine whether the higher hypoperfusion intensity ratio is associated with a worse NIHSS score at 24 hours post-mechanical thrombectomy and early neurologic deterioration in LVO versus DMVO acute ischemic stroke.

MATERIALS AND METHODS

This was a retrospective study of 231 patients with acute ischemic stroke with LVO or DMVO amenable for mechanical thrombectomy and available CTP for hypoperfusion intensity ratio assessment pre-mechanical thrombectomy. Clinical and imaging characteristics were abstracted from the medical records. The primary outcome was the NIHSS score at 24 hours post-mechanical thrombectomy. The secondary outcome was early neurologic deterioration, defined as a >4-point increase in the NIHSS score between the initial assessment and 24 hours post-mechanical thrombectomy. All analyses were first conducted in the entire cohort and then separately for the LVO versus DMVO groups.

RESULTS

The optimal hypoperfusion intensity ratio threshold to detect early neurologic deterioration was 0.54. A hypoperfusion intensity ratio ≥ 0.54 was more frequently present in LVO versus DMVO (n = 37 [77.1%] versus n = 11 [22.9%]; P < .001). On multivariable linear regression, the hypoperfusion intensity ratio ≥ 0.54 was independently associated with a worse NIHSS score at 24 hours post-mechanical thrombectomy in the entire cohort (β = 0.163; P = .002) and the LVO group (β = 0.210; P = .005), but not in the DMVO group. The early neurologic deterioration occurred in 26 (11.3%) subjects. On multivariable logistic regression, there was no association of the hypoperfusion intensity ratio ≥ 0.54 with early neurologic deterioration in the entire cohort. However, when analyzed separately, a hypoperfusion intensity ratio ≥ 0.54 significantly increased the odds of early neurologic deterioration in subjects with LVO (OR = 5.263; 95% CI, 1.170-23.674; P = .030) but not in the DMVO group.

CONCLUSIONS

The hypoperfusion intensity ratio ≥ 0.54 was independently associated with a worse 24-hour post-mechanical thrombectomy NIHSS score and early neurologic deterioration in LVO, but not in DMVO acute ischemic stroke. Pending confirmation in future, prospective studies assessing the hypoperfusion intensity ratio may help identify patients at risk of secondary decline to improve peri-thrombectomy care and clinical decision-making.

Is intraprocedural intravenous aspirin safe for patients who require emergent extracranial stenting during mechanical thrombectomy?

BACKGROUND

Intraoperative antiplatelet therapy is recommended for emergent stenting during mechanical thrombectomy (MT). Most patients undergoing MT are also given thrombolysis. Antiplatelet agents are contraindicated within 24 hours of thrombolysis. We evaluated outcomes and complications of patients stented with and without intravenous aspirin during MT.

METHODS

All patients who underwent emergent extracranial stenting during MT at the Royal Stoke University Hospital, UK between 2010 and 2020, were included. Patients were thrombolysed before MT, unless contraindicated. Aspirin 500 mg intravenously was given intraoperatively at the discretion of the operator. Symptomatic intracranial haemorrhage (sICH) and the National Institutes for Health Stroke Scale score (NIHSS) were recorded at 7 days, and mortality and functional recovery (modified Rankin Scale: mRS ≤2) at 90 days.

RESULTS

Out of 565 patients treated by MT 102 patients (median age 67 IQR 57-72 years, baseline median NIHSS 18 IQR 13-23, 76 (75%) thrombolysed) had a stent placed. Of these 49 (48%) were given aspirin and 53 (52%) were not. Patients treated with aspirin had greater NIHSS improvement (median 8 IQR 1-16 vs median 3 IQR -9-8 points, p=0.003), but there were no significant differences in sICH (2/49 (4%) vs 9/53 (17%)), mRS ≤2 (25/49 (51%) vs 19/53 (36%)) and mortality (10/49 (20%) vs 12/53 (23%)) with and without aspirin. NIHSS improvement (median 12 IQR 4-18 vs median 7 IQR -7-10, p=0.01) was greater, and mortality was lower (4/33 (12%) vs 6/15 (40%), p=0.05) when aspirin was combined with thrombolysis, than for aspirin alone, with no increase in bleeding.

CONCLUSION

Our findings based on registry data derived from routine clinical care suggest that intraprocedural intravenous aspirin in patients undergoing emergent stenting during MT does not increase sICH and is associated with good clinical outcomes, even when combined with intravenous thrombolysis.

Communicating Arteries and Leptomeningeal Collaterals: A Synergistic but Independent Effect on Patient Outcomes after Stroke

The collateral system is a compensatory mechanism activated in the acute phase of an ischemic stroke. It increases brain perfusion to the hypoperfused area. Arteries of the Willis' circle supply antegrade blood flow, while pial (leptomeningeal) arteries direct blood via retrograde flow. The aim of our retrospective study was to investigate the relationship between both collateral systems, computed tomography perfusion (CTP) values, and functional outcomes in acute stroke patients. Overall, 158 patients with anterior circulation stroke who underwent mechanical thrombectomy were included in the study. We analyzed the presence of communicating arteries and leptomeningeal arteries on computed tomography angiography. Patients were divided into three groups according to their collateral status. The main outcomes were the rate of functional independence 3 months after stroke (modified Rankin scale score, mRS) and mortality rate. Our study suggests that the collateral status, as indicated by the three groups (unfavorable, intermediate, and favorable), is linked to CT perfusion parameters, potential recuperation ratio, and stroke outcomes. Patients with favorable collateral status exhibited smaller core infarct and penumbra volumes, higher mismatch ratios, better potential for recuperation, and improved functional outcomes compared to patients with unfavorable or intermediate collateral status.

Current State of Evidence for Neuroimaging Paradigms in Management of Acute Ischemic Stroke

Stroke is the chief differential diagnosis in patient presenting to the emergency room with abrupt onset focal neurological deficits. Neuroimaging, including non-contrast computed tomography (CT), magnetic resonance imaging (MRI), vascular and perfusion imaging, is a cornerstone in the diagnosis and treatment decision-making. This review examines the current state of evidence behind the different imaging paradigms for acute ischemic stroke diagnosis and treatment, including current recommendations from the guidelines. Non-contrast CT brain, or in some centers MRI, can help differentiate ischemic stroke and intracerebral hemorrhage (ICH), a pivotal juncture in stroke diagnosis and treatment algorithm, especially for early window thrombolytics. Advanced imaging such as MRI or perfusion imaging can also assist making a diagnosis of ischemic stroke versus mimics such as migraine, Todd's paresis, or functional disorders. Identification of medium-large vessel occlusions with CT or MR angiography triggers consideration of endovascular thrombectomy (EVT), with additional perfusion imaging help identify salvageable brain tissue in patients who are likely to benefit from reperfusion therapies, particularly in the ≥6 h window. We also review recent advances in neuroimaging and ongoing trials in key therapeutic areas and their imaging selection criteria to inform the readers on potential future transitions into use of neuroimaging for stroke diagnosis and treatment decision making. ANN NEUROL 2024;95:1017-1034.

Prediction of cerebral hemorrhagic transformation after thrombectomy using a deep learning of dual-energy CT

OBJECTIVES

To develop and validate a deep learning model for predicting hemorrhagic transformation after endovascular thrombectomy using dual-energy computed tomography (CT).

MATERIALS AND METHODS

This was a retrospective study from a prospective registry of acute ischemic stroke. Patients admitted between May 2019 and February 2023 who underwent endovascular thrombectomy for acute anterior circulation occlusions were enrolled. Hemorrhagic transformation was defined using follow-up magnetic resonance imaging or CT. The deep learning model was developed using post-thrombectomy dual-energy CT to predict hemorrhagic transformation within 72 h. Temporal validation was performed with patients who were admitted after July 2022. The deep learning model's performance was compared with a logistic regression model developed from clinical variables using the area under the receiver operating characteristic curve (AUC).

RESULTS

Total of 202 patients (mean age 71.4 years ± 14.5 [standard deviation], 92 men) were included, with 109 (54.0%) patients having hemorrhagic transformation. The deep learning model performed consistently well, showing an average AUC of 0.867 (95% confidence interval [CI], 0.815-0.902) upon five-fold cross validation and AUC of 0.911 (95% CI, 0.774-1.000) with the test dataset. The clinical variable model showed an AUC of 0.775 (95% CI, 0.709-0.842) on the training dataset (p < 0.01) and AUC of 0.634 (95% CI, 0.385-0.883) on the test dataset (p = 0.06).

CONCLUSION

A deep learning model was developed and validated for prediction of hemorrhagic transformation after endovascular thrombectomy in patients with acute stroke using dual-energy computed tomography.

CLINICAL RELEVANCE STATEMENT

This study demonstrates that a convolutional neural network (CNN) can be utilized on dual-energy computed tomography (DECT) for the accurate prediction of hemorrhagic transformation after thrombectomy. The CNN achieves high performance without the need for region of interest drawing.

KEY POINTS

• Iodine leakage on dual-energy CT after thrombectomy may be from blood-brain barrier disruption. • A convolutional neural network on post-thrombectomy dual-energy CT enables individualized prediction of hemorrhagic transformation. • Iodine leakage is an important predictor of hemorrhagic transformation following thrombectomy for ischemic stroke.

Prognostic implications of intracranial haemorrhage on dual-energy CT immediately following endovascular treatment for acute ischemic stroke

OBJECTIVE

To describe the incidence, risk factors, and prognostic relevance of intracranial haemorrhage (ICH) immediately after endovascular treatment (EVT) for ischaemic stroke in the anterior circulation.

METHODS

EVT records from 2010 to 2019 were screened. Included patients underwent DECT within 3h post-EVT. Virtual native reconstructions were evaluated for ICH according to the Heidelberg criteria and grouped into Heidelberg classes (HCs): [HC1] haemorrhagic infarction (HI)1, HI2 and parenchymal haematoma (PH)1; [HC2] PH2; [HC3] i.a. intraventricular and subarachnoid haemorrhage. If ICH corresponding to multiple HCs was observed, we assumed that the (largest) parenchymal ICH would have the greatest prognostic impact. Hence, a single HC was attributed by the following order of severity: HC2, HC1, HC3. The primary outcome was the modified Rankin Scale (mRS) at 90 days. The effect of asymptomatic ICH (aICH) and symptomatic ICH (sICH) of (1) HC1 or HC2 and (2) HC3 on patient outcomes was evaluated with multivariable regression after multiple imputation.

RESULTS

Out of 651 records, 498 patients were included. Eighty-one (16%) patients showed ICH on post-EVT DECT, of which 19 were classified as HC1 (21% symptomatic), 6 as HC2 (100% symptomatic), and 56 as HC3 (14% symptomatic). ICH development was mainly associated with unfavourable procedural characteristics. Both aICH and sICH of HC1 or HC2 were associated with the mRS (aICH: adjusted [a]cOR 4.92, 95%CI [1.48-16.35]; sICH: acOR 12.97, 95%CI [2.39-70.26]) and mortality (aICH: aOR 10.08, 95%CI [2.48-40.88]; sICH: aOR 9.92, 95%CI [1.48-66.31]). Likewise, sICH of HC3 was associated with the mRS and mortality (acOR 19.91, 95%CI [4.03-98.35], and aOR 13.23, 95%CI [2.27-77.18], respectively). aICH of HC3 was not significantly associated with the mRS or mortality (acOR 0.87, 95%CI [0.48-1.57], and cOR 0.84, 95%CI [0.32-2.20], respectively).

CONCLUSIONS

Immediate post-EVT ICH is a frequent finding. Except for aICH of HC3, any ICH is associated with poor long-term clinical outcomes.

Patchy profile sign in RAPID software: a specific marker for intracranial atherosclerotic stenosis in acute ischemic stroke

Purpose

Identifying the etiology of acute ischemic stroke (AIS) before endovascular treatment (EVT) is important but challenging. In CT perfusion imaging processed by perfusion software, we observed a phenomenon called patchy profile sign (PPS), that is, the hypoperfusion morphology in RAPID software is a discontinuous sheet pattern. This phenomenon is predominantly observed in patients diagnosed with intracranial atherosclerotic stenosis (ICAS). The study intends to assess whether the PPS can be used to differentiate ICAS from intracranial embolism.

Method

Patients with AIS due to M1 segment occlusion of the MCA who underwent mechanical thrombectomy were retrospectively enrolled. The receiver operating characteristic (ROC) curve analysis was performed to assess the value of PPS in predicting ICAS. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the PPS for prediction of ICAS were calculated.

Results

A total of 51 patients were included in the study. The PPS was observed in 10 of 19 (52.6%) patients with ICAS, and in 2 of 32 (6.3%) patients with intracranial embolism (p < 0.001). Interobserver agreement for identifying PPS was excellent (κ = 0.944). The sensitivity, specificity, PPV, NPV, and accuracy of the PPS for predicting ICAS were 52.6, 93.8, 83.3, 76.9, and 78.4%, respectively.

Conclusion

The PPS on RAPID software is an imaging marker with high specificity for ICAS. Larger sample sizes are imperative to validate the findings.

Hypoperfusion index ratio and pretreatment with intravenous thrombolysis are independent predictors of good functional outcome in acute ischemic stroke patients with large vessel occlusion treated with acute reperfusion therapies

INTRODUCTION

We aimed to investigate the performance of several neuroimaging markers provided by perfusion imaging of Acute Ischemic Stroke (AIS) patients with large vessel occlusion (LVO) in order to predict clinical outcomes following reperfusion treatments.

METHODS

We prospectively evaluated consecutive AIS patients with LVO who were treated with reperfusion therapies, during a six-year period. In order to compare patients with good (mRS scores 0-2) and poor (mRS scores 3-6) functional outcomes, data regarding clinical characteristics, the Alberta Stroke Programme Early Computed Tomography Score (ASPECTS) based on unenhanced computed tomography (CT), CT angiography collateral status and perfusion parameters including ischemic core, hypoperfusion volume, mismatch volume between core and penumbra, Tmax > 10 s volume, CBV index and the Hypoperfusion Index Ratio (HIR) were assessed.

RESULTS

A total of 84 acute stroke patients with LVO who met all the inclusion criteria were enrolled. In multivariable logistic regression models increasing age (odds ratio [OR]: 0.93; 95%CI: 0.88-0.96, p = 0.001), lower admission National Institute of Health Stroke Scale (NIHSS)-score (OR: 0.88; 95%CI: 0.80-0.95, p = 0.004), pretreatment with intravenous thrombolysis (OR: 3.83; 95%CI: 1.29-12.49, p = 0.019) and HIR (OR:0.36; 95%CI: 0.10-0.95, p = 0.042) were independent predictors of good functional outcome at 3 months. The initial univariable associations between HIR and higher likelihood for symptomatic intracranial hemorrhage (sICH) and parenchymal hematoma type 2 (PH2) were attenuated in multivariable analyses failing to reach statistical significance.

DISCUSSION

Our pilot observational study of unselected AIS patients with LVO treated with reperfusion therapies demonstrated that pre-treatment low HIR in perfusion imaging and IVT were associated with better functional outcomes.

Utilizing imaging parameters for functional outcome prediction in acute ischemic stroke: A machine learning study

BACKGROUND AND PURPOSE

We aimed to predict the functional outcome of acute ischemic stroke patients with anterior circulation large vessel occlusions (LVOs), irrespective of how they were treated or the severity of the stroke at admission, by only using imaging parameters in machine learning models.

METHODS

Consecutive adult patients with anterior circulation LVOs who were scanned with CT angiography (CTA) and CT perfusion were queried in this single-center, retrospective study. The favorable outcome was defined as a modified Rankin score (mRS) of 0-2 at 90 days. Predictor variables included only imaging parameters. CatBoost, XGBoost, and Random Forest were employed. Algorithms were evaluated using the area under the receiver operating characteristic curve (AUROC), the area under the precision-recall curve (AUPRC), accuracy, Brier score, recall, and precision. SHapley Additive exPlanations were implemented.

RESULTS

A total of 180 patients (102 female) were included, with a median age of 69.5. Ninety-two patients had an mRS between 0 and 2. The best algorithm in terms of AUROC was XGBoost (0.91). Furthermore, the XGBoost model exhibited a precision of 0.72, a recall of 0.81, an AUPRC of 0.83, an accuracy of 0.78, and a Brier score of 0.17. Multiphase CTA collateral score was the most significant feature in predicting the outcome.

CONCLUSIONS

Using only imaging parameters, our model had an AUROC of 0.91 which was superior to most previous studies, indicating that imaging parameters may be as accurate as conventional predictors. The multiphase CTA collateral score was the most predictive variable, highlighting the importance of collaterals.

Sex Alters the Effect of Perfusion Deficits on Functional Outcome in Patients with Acute Ischemic Stroke Undergoing Mechanical Thrombectomy

INTRODUCTION

The discourse surrounding differences in cerebral hemodynamics and clinical outcomes among male and female patients treated with mechanical thrombectomy (MT) for acute ischemic stroke (AIS) remains unresolved. We aimed to elucidate these differences by employing computed tomography perfusion (CTP) imaging before MT and examining the influence of perfusion deficits on the 90-day functional outcome.

METHODS

This single-center retrospective analysis involved patients with anterior circulation AIS treated with MT at the Comprehensive Stroke Center, University Hospital, Krakow, from January 2019 to July 2023. We compared male and female patients in terms of baseline characteristics, CTP deficits, hypoperfusion intensity ratio (HIR, defined as T10max/T6max), and complications. The endpoints included the 90-day excellent functional outcome, defined as modified Rankin Score <2, and the 90-day mortality rate.

RESULTS

We included 794 patients, of whom 408 were female (51.4%). Female patients had a smaller early infarct volume (median [interquartile range]: 7 mL [0-24.8] vs. 10 mL [0-33], p = 0.004), smaller penumbra volume (77.5 mL [46-117] vs. 99.5 mL [59.8-140], p < 0.001), lower HIR (0.34 [0.16-0.5] vs. 0.37 [0.2-9.53], p = 0.043) and were less likely to achieve an excellent functional outcome (55.6% vs. 66.1%, p = 0.003). For every 10 mL increase in early infarct volume, the odds for achieving an excellent outcome were lower in females (odds ratio [OR]: 0.82 [95% confidence interval: 0.73-0.92]) compared to males (OR: 0.96 [0.88-1.04]), whereas the risk of death was higher for females (OR: 1.25 [1.13-1.39] than for males (OR: 1.05 [0.98-1.14]).

DISCUSSION

Despite more favorable cerebral hemodynamic profile, female AIS patients have worse outcomes than their male counterparts. This effect seems to be independently mediated by the more pronounced impact of early infarct volume on the prognosis in female patients. These findings underscore the possible explanatory power arising from sex-specific interpretation of early infarct volume in clinical practice.

Timing of acute carotid artery stenting for tandem lesions in patients with acute ischemic stroke: A Maastricht Stroke Quality Registry (MaSQ-Registry) study

BACKGROUND

To better understand the influence of treatment strategies on outcomes for patients with tandem lesions undergoing acute internal carotid artery (ICA) stenting during endovascular treatment (EVT), this study compared clinical, technical, and safety outcomes in patients with acute ischemic stroke due to a large vessel occlusion (LVO) who underwent ICA stenting before versus after intracranial thrombectomy.

METHODS

This single-center retrospective cohort study included patients who underwent EVT due to a LVO and periprocedural ICA stenting for significant ICA stenosis or occlusion between September 2020 and January 2023. Data were extracted from the Maastricht Stroke Quality Registry (MaSQ-Registry). Primary outcome was the modified Rankin Scale (mRS) at 3 months. Secondary outcomes included procedure times, number of total thrombectomy attempts, first-attempt excellent recanalization rates (extended Thrombolysis In Cerebral Infarction (eTICI) ≥ 2C after one thrombectomy attempt), and safety outcomes.

RESULTS

This study included 50 patients. Thirty-one patients (62%) underwent ICA stenting before intracranial thrombectomy. No significant differences between both groups were found regarding mRS, total procedure time, number of total thrombectomy attempts, first-attempt excellent recanalization, or complications. Time between groin puncture and recanalization (reperfusion time) was significantly longer in patients who had ICA stenting before intracranial thrombectomy versus after intracranial thrombectomy (45 min versus 28 min, P = 0.004).

CONCLUSION

ICA stenting after intracranial thrombectomy in patients with tandem lesions undergoing EVT did not lead to better patient outcomes compared to stenting before intracranial thrombectomy, despite shorter reperfusion times.

Automated evaluation of collateral circulation for outcome prediction in acute ischemic stroke

INTRODUCTION

The assessment of collateral circulation in acute ischemic stroke management is essential. Modern tools, such as Brainomix's e-CTA, powered by artificial intelligence, provide detailed insights into collateral assessment. This retrospective study aims to identify factors contributing to favorable collateral status and compare outcomes between patients with good collaterals (grade 3) and fair collaterals (grade 0-2).

METHOD

This retrospective study included 97 patients admitted to the Stroke Unit at the Hospital de Clínicas of the Federal University of Paraná, Brazil, from September 2021 to January 2023. Comparative analyses involved demographic factors, cardiovascular risk factors, and the combined outcome of mortality and moderate to severe disability at discharge, 30-day, and 90-day follow-ups.

RESULTS

Among the 97 cases, 58.8 % showed 'good collaterals' with a grade 3 status. Variables affecting collateral status included age (p = 0.042), neutrophil-lymphocyte ratio (p = 0.005), and initial NIHSS scores (p<0.001). The presence of good collaterals according to e-CTA reduced the odds of death and moderate-severe disability at discharge (p = 0.003; OR 0.27) and at 30 days (p = 0.015; OR 0.33), although this effect diminished at the 90-day mark after multivariate analysis.

DISCUSSION

Automated collateral assessment through e-CTA is a valuable tool in acute ischemic stroke evaluation. Good e-CTA collateral score serve as a promising imaging biomarker, guiding informed clinical decisions during Stroke Unit hospitalizations. This study highlights the relationship between collaterals and stroke outcomes and underscores the potential for AI-driven tools to enhance stroke care management.

Absent leptomeningeal collateralization is associated with greatest benefit from mechanical thrombectomy in the 6-24 hour time window

INTRODUCTION

The impact of leptomeningeal collateralization on the efficacy of mechanical thrombectomy (MT) in patients with anterior circulation large vessel occlusion (aLVO) presenting in the 6-24 h time window remains poorly elucidated.

PATIENTS AND METHODS

Retrospective multicenter study of aLVO patients presenting between 6 and 24 h after stroke onset who received MT plus Best Medical Treatment (BMT) or BMT alone. Leptomeningeal collateralization was assessed using single-phase computed tomography angiography (grade 0: no filling; grade 1: filling ⩽50%; grade 2: filling >50% but <100%; grade 3: filling 100% of the occluded territory). Inverse probability of treatment weighted ordinal regression was performed to assess the association between treatment and shift of the modified Rankin Scale (mRS) score toward lower categories at 3 months. We used interaction analysis to explore differential treatment effects on functional outcomes (probabilities for each mRS subcategory at 3 months) at different collateral grades.

RESULTS

Among 363 included patients, 62% received MT + BMT. Better collateralization was associated with better functional outcomes at 3 months in the BMT alone group (collateral grade 1 vs 0: acOR 5.06, 95% CI 2.33-10.99). MT + BMT was associated with higher odds of favorable functional outcome at 3 months (acOR 1.70, 95% CI 1.11-2.62) which was consistent after adjustment for collateral status (acOR 1.54, 95% CI 1.01-2.35). Regarding treatment effect modification, patients with absent collateralization had higher probabilities for a mRS of 0-4 and a lower mortality at 3 months for the MT + BMT group.

DISCUSSION AND CONCLUSION

In the 6-to-24-h time window, aLVO patients with absent leptomeningeal collateralization benefit most from MT + BMT, indicating potential advantages for this group despite their poorer baseline prognosis.

Prolonged venous transit on perfusion imaging is associated with higher odds of mortality in successfully reperfused patients with large vessel occlusion stroke

BACKGROUND

Poor venous outflow (VO) profiles are associated with unfavorable outcomes in patients with acute ischemic stroke caused by large vessel occlusion (AIS-LVO), despite achieving successful reperfusion. The objective of this study is to assess the association between mortality and prolonged venous transit (PVT), a novel visual qualitative VO marker on CT perfusion (CTP) time to maximum (Tmax) maps.

METHODS

We performed a retrospective analysis of prospectively collected data from consecutive adult patients with AIS-LVO with successful reperfusion (modified Thrombolysis in Cerebral Infarction 2b/2c/3). PVT+ was defined as Tmax ≥10 s timing on CTP Tmax maps in at least one of the following: superior sagittal sinus (proximal venous drainage) and/or torcula (deep venous drainage). PVT- was defined as lacking this in both regions. The primary outcome was mortality at 90 days. In a 1:1 propensity score-matched cohort, regressions were performed to determine the effect of PVT on 90-day mortality.

RESULTS

In 127 patients of median (IQR) age 71 (64-81) years, mortality occurred in a significantly greater proportion of PVT+ patients than PVT- patients (32.5% vs 12.6%, P=0.01). This significant difference persisted after matching (P=0.03). PVT+ was associated with a significantly increased likelihood of 90-day mortality (OR 1.22 (95% CI 1.02 to 1.46), P=0.03) in the matched cohort.

CONCLUSIONS

PVT+ was significantly associated with 90-day mortality despite successful reperfusion therapy in patients with AIS-LVO. PVT is a simple VO profile marker with potential as an adjunctive metric during acute evaluation of AIS-LVO patients. Future studies will expand our understanding of using PVT in the evaluation of patients with AIS-LVO.

Endovascular Treatment for Acute Isolated Internal Carotid Artery Occlusion : A Propensity Score Matched Multicenter Study

PURPOSE

The benefit of endovascular treatment (EVT) in patients with acute symptomatic isolated occlusion of the internal carotid artery (ICA) without involvement of the middle and anterior cerebral arteries is unclear. We aimed to compare clinical and safety outcomes of best medical treatment (BMT) versus EVT + BMT in patients with stroke due to isolated ICA occlusion.

METHODS

We conducted a retrospective multicenter study involving patients with isolated ICA occlusion between January 2016 and December 2020. We stratified patients by BMT versus EVT and matched the groups using propensity score matching (PSM). We assessed the effect of treatment strategy on favorable outcome (modified Rankin scale ≤ 2) 90 days after treatment and compared reduction in NIHSS score at discharge, rates of symptomatic intracranial hemorrhage (sICH) and 3‑month mortality.

RESULTS

In total, we included 149 patients with isolated ICA occlusion. To address imbalances, we matched 45 patients from each group using PSM. The rate of favorable outcomes at 90 days was 56% for EVT and 38% for BMT (odds ratio, OR 1.89, 95% confidence interval, CI 0.84-4.24; p = 0.12). Patients treated with EVT showed a median reduction in NIHSS score at discharge of 6 points compared to 1 point for BMT patients (p = 0.02). Rates of symptomatic intracranial hemorrhage (7% vs. 4%; p = 0.66) and 3‑month mortality (11% vs. 13%; p = 0.74) did not differ between treatment groups. Periprocedural complications of EVT with early neurological deterioration occurred in 7% of cases.

CONCLUSION

Although the benefit on functional outcome did not reach statistical significance, the results for NIHSS score improvement, and safety support the use of EVT in patients with stroke due to isolated ICA occlusion.

Preliminary findings on diagnostic performance of computed tomography perfusion images for intracranial arterial stenosis: a retrospective study

OBJECTIVES

Computed tomographic perfusion (CTP) can play an auxiliary role in the selection of patients with acute ischemic stroke for endovascular treatment. However, data on CTP in non-stroke patients with intracranial arterial stenosis are scarce. We aimed to investigate images in patients with asymptomatic intracranial arterial stenosis to determine the detection accuracy and interpretation time of large/medium-artery stenosis or occlusion when combining computed tomographic angiography (CTA) and CTP images.

METHODS

We retrospectively reviewed 39 patients with asymptomatic intracranial arterial stenosis from our hospital database from January 2021 to August 2023 who underwent head CTP, head CTA, and digital subtraction angiography (DSA). Head CTA images were generated from the CTP data, and the diagnostic performance for each artery was assessed. Two readers independently interpreted the CTA images before and after CTP, and the results were analyzed.

RESULTS

After adding CTP maps, the accuracy (area under the curve) of diagnosing internal carotid artery (R1: 0.847 vs. 0.907, R2: 0.776 vs. 0.887), middle cerebral artery (R1: 0.934 vs. 0.933, R2: 0.927 vs. 0.981), anterior cerebral artery (R1: 0.625 vs. 0.750, R2: 0.609 vs. 0.750), vertebral artery (R1: 0.743 vs. 0.764, R2: 0.748 vs. 0.846), and posterior cerebral artery (R1: 0.390 vs. 0.575, R2: 0.390 vs. 0.585) occlusions increased for both readers (p < 0.05). Mean interpretation time (R1: 72.4 ± 6.1 s vs. 67.7 ± 6.4 s, R2: 77.7 ± 3.8 s vs. 72.6 ± 4.7 s) decreased when using a combination of both images both readers (p < 0.001).

CONCLUSIONS

The addition of CTP images improved the accuracy of interpreting CTA images and reduced the interpretation time in asymptomatic intracranial arterial stenosis. These findings support the use of CTP imaging in patients with asymptomatic intracranial arterial stenosis.

Neuroprotection during Thrombectomy for Acute Ischemic Stroke: A Review of Future Therapies

Stroke is a major cause of death and disability worldwide. Endovascular thrombectomy has been impactful in decreasing mortality. However, many clinical results continue to show suboptimal functional outcomes despite high recanalization rates. This gap in recanalization and symptomatic improvement suggests a need for adjunctive therapies in post-thrombectomy care. With greater insight into ischemia-reperfusion injury, recent preclinical testing of neuroprotective agents has shifted towards preventing oxidative stress through upregulation of antioxidants and downstream effectors, with positive results. Advances in multiple neuroprotective therapies, including uric acid, activated protein C, nerinetide, otaplimastat, imatinib, verapamil, butylphthalide, edaravone, nelonemdaz, ApTOLL, regional hypothermia, remote ischemic conditioning, normobaric oxygen, and especially nuclear factor erythroid 2-related factor 2, have promising evidence for improving stroke care. Sedation and blood pressure management in endovascular thrombectomy also play crucial roles in improved stroke outcomes. A hand-in-hand approach with both endovascular therapy and neuroprotection may be the key to targeting disability due to stroke.

Predicting outcome in acute stroke with large vessel occlusion-application and validation of MR PREDICTS in the ESCAPE-NA1 population

BACKGROUND

Predicting outcome after endovascular treatment for acute ischemic stroke is challenging. We aim to investigate differences between predicted and observed outcomes in patients with acute ischemic stroke treated with endovascular treatment and to evaluate the performance of a validated outcome prediction score.

PATIENTS AND METHODS

MR PREDICTS is an outcome prediction tool based on a logistic regression model designed to predict the treatment benefit of endovascular treatment based on the MR CLEAN and HERMES populations. ESCAPE-NA1 is a randomized trial of nerinetide vs. placebo in patients with acute stroke and large vessel occlusion. We applied MR PREDICTS to patients in the control arm of ESCAPE-NA1. Model performance was assessed by calculating its discriminative ability and calibration.

RESULTS

Overall, 556/1105 patients (50.3%) in the ESCAPE-NA1-trial were randomized to the control arm, 435/556 (78.2%) were treated within 6 h of symptom onset. Good outcome (modified Rankin scale 0-2) at 3 months was achieved in 275/435 patients (63.2%), the predicted probability of good outcome was 52.5%. Baseline characteristics were similar in the study and model derivation cohort except for age (ESCAPE-NA1: mean: 70 y vs. HERMES: 66 y), hypertension (72% vs. 57%), and collaterals (good collaterals, 15% vs. 44%). Compared to HERMES we observed higher rates of successful reperfusion (TICI 2b-3, ESCAPE-NA1: 87% vs. HERMES: 71%) and faster times from symptom onset to reperfusion (median: 201 min vs. 286 min). Model performance was good, indicated by a c-statistic of 0.76 (95%confidence interval: 0.71-0.81).

CONCLUSION

Outcome-prediction using models created from HERMES data, based on information available in the emergency department underestimated the actual outcome in patients with acute ischemic stroke and large vessel occlusion receiving endovascular treatment despite overall good model performance, which might be explained by differences in quality of and time to reperfusion. These findings underline the importance of timely and successful reperfusion for functional outcomes in acute stroke patients.

Automated advanced imaging in acute ischemic stroke. Certainties and uncertainties

The purpose of this is study was to review pearls and pitfalls of advanced imaging, such as computed tomography perfusion and diffusion-weighed imaging and perfusion-weighted imaging in the selection of acute ischemic stroke (AIS) patients suitable for endovascular treatment (EVT) in the late time window (6-24 h from symptom onset). Advanced imaging can quantify infarct core and ischemic penumbra using specific threshold values and provides optimal selection parameters, collectively called target mismatch. More precisely, target mismatch criteria consist of core volume and/or penumbra volume and mismatch ratio (the ratio between total hypoperfusion and core volumes) with precise cut-off values. The parameters of target mismatch are automatically calculated with dedicated software packages that allow a quick and standardized interpretation of advanced imaging. However, this approach has several limitations leading to a misclassification of core and penumbra volumes. In fact, automatic software platforms are affected by technical artifacts and are not interchangeable due to a remarkable vendor-dependent variability, resulting in different estimate of target mismatch parameters. In addition, advanced imaging is not completely accurate in detecting infarct core, that can be under- or overestimated. Finally, the selection of candidates for EVT remains currently suboptimal due to the high rates of futile reperfusion and overselection caused by the use of very stringent inclusion criteria. For these reasons, some investigators recently proposed to replace advanced with conventional imaging in the selection for EVT, after the demonstration that non-contrast CT ASPECTS and computed tomography angiography collateral evaluation are not inferior to advanced images in predicting outcome in AIS patients treated with EVT. However, other authors confirmed that CTP and PWI/DWI postprocessed images are superior to conventional imaging in establishing the eligibility of patients for EVT. Therefore, the routine application of automatic assessment of advanced imaging remains a matter of debate. Recent findings suggest that the combination of conventional and advanced imaging might improving our selection criteria.

Outcome prediction value of critical area perfusion score for acute basilar artery occlusion

PURPOSE

To investigate the performance of the Critical Area Perfusion Score (CAPS), based on computed tomography perfusion (CTP) time to maximum (Tmax) > 10s maps, to predict the outcome in acute basilar artery occlusion (BAO) in patients undergoing endovascular treatment (EVT).

METHODS

We perform a retrospective analysis of a prospectively collected database of acute BAO treated with EVT in a comprehensive stroke center. The favorable outcome was defined as the 90-day modified Rankin Scale (mRS) ≤ 3. We performed the logistic regression analysis to find the independent predictors of the favorable outcome. Then, we used receiver operating characteristic analyses to assess the predictive value of the imaging parameters, including CAPS, Posterior Circulation Alberta Stroke Program Early CT Score (PC-ASPECTS), pons midbrain index (PMI), posterior circulation computed tomography angiography (PC-CTA) score, Basilar Artery on Computed Tomography Angiography (BATMAN) score, and CTP parameters. Finally, the Delong test was used to compare the area under the curve (AUC) of CAPS against the other imaging parameters.

RESULTS

Of the 65 enrolled patients, the incidence of the favorable outcome was 44.6% (29/65). Low CAPS (per 1- point increased odds ratio [OR], 0.43; 95% confidence interval [CI], 0.22-0.86; P = 0.017) and admission National Institutes of Health Stroke Scale (NIHSS) (per 1- point increased OR, 0.80; 95% CI, 0.70-0.91; P = 0.001) were independently associated with favorable outcome. The AUC of CAPS was 0.83 (95% CI, 0.74-0.93; P < 0.001) with ≤ 3 cut-off value, 89.66% sensitivity, 77.22% specificity, and 80.00% accuracy, which was greater than the other imaging parameters (All P for Delong test < 0.05).

CONCLUSIONS

CAPS was the most accurate imaging-based outcome predictor in acute BAO patients. Future large prospective multicenter studies are needed to verify these results.

The ACORNS grading scale: a novel tool for the prediction of malignant brain edema after endovascular thrombectomy

BACKGROUND

To develop and validate a novel tool for predicting the development of malignant brain edema (MBE) in large vessel occlusion stroke patients after endovascular thrombectomy (EVT).

METHODS

We used a prospectively registered population of EVT patients from three comprehensive stroke centers. The population was randomly divided into two subsets (7:3): a training cohort and an internal validation cohort. External validation was performed using the Endovascular Treatment for Acute Anterior Circulation Ischemic Stroke Registry in China (ACTUAL) database. MBE was defined as (1) hypodense parenchyma in at least 50% of the middle cerebral artery and signs of local brain swelling, and (2) a midline shift of ≥5 mm at the septum pellucidum or pineal gland with obliteration of the basal cisterns. The model was constructed using logistic regression analysis. The performance of the model was examined in terms of discrimination and calibration.

RESULTS

After adjusting for other confounders, baseline National Institutes of Health Stroke Scale (NIHSS) and Alberta Stroke Program Early CT (ASPECT) scores, a clinical history of hypertension, collateral status, intravenous thrombolysis before thrombectomy, fasting blood glucose, reperfusion status, and occlusion site were found to be independent predictors of MBE. These variables were combined to create the ACORNS grading scale. The areas under the curve in receiver operating curve analysis were 0.850 (95% CI 0.816 to 0.884), 0.874 (95% CI 0.821 to 0.926), and 0.785 (95% CI 0.740 to 0.829) for the training, internal validation, and external validation cohorts, respectively, indicating good discriminative performance in the validation cohorts.

CONCLUSIONS

The ACORNS grading scale is an accurate and easily applicable model for the prediction of the development of MBE after EVT.

Effect of prolonged microcirculation time after thrombectomy on the outcome of acute stroke

BACKGROUND

Although recanalization can be successful, microcirculatory dysfunction is common in acute large vessel occlusive stroke (LVOS). We assessed the microcirculation time by postprocessing software and analyzed its impact on prognosis in patients treated with mechanical thrombectomy (MT).

METHODS

Patients with acute LVOS treated with MT were retrospectively enrolled consecutively. We measured the time to peak (TTP) and cerebral circulation time (CCT) in regions of interest on digital subtraction angiography using syngo iFlow software (Siemens Healthineers, Forchheim, Germany). A modified Rankin score ≤2 at 90 days was defined as a favorable outcome. Logistic regression was used to analyze the effect of each time parameter on prognosis. Then, we included time parameters in the baseline model to construct receiver operating characteristic (ROC) curves to assess the predictive ability for prognosis.

RESULTS

A total of 215 patients were finally included. Of them, 118 (54.9%) had a favourable outcome at 90 days. Multivariate analysis showed that the microvascular cerebral circulation time (mCCT) was significantly associated with poor outcomes (odds ratio (OR) 2.061, 95% confidence interval (CI) 1.414 to 3.005 p<0.001). The area under the ROC curve was significantly enhanced by including mCCT in the baseline model (0.859 vs 0.829, p=0.016, DeLong test).

CONCLUSIONS

The mCCT immediately after recanalization is a powerful predictive factor for 90-day functional prognosis.

Alberta Stroke Program Early CT Score and collateral status predict target mismatch in large vessel occlusion with delayed time windows

BACKGROUND

The Alberta Stroke Program Early CT Score (ASPECTS) and collateral score (CS) are two readily available imaging metrics for the evaluation of acute ischemic stroke (AIS) with large vessel occlusion (LVO).

OBJECTIVE

To investigate the predictive value of the ASPECTS combined with CS in detecting patients with CT perfusion (CTP) target mismatch in delayed time windows.

METHODS

One hundred and sixty-four patients with LVO-AIS were included. ASPECTS was assessed on non-contrast CT (NCCT). CS was evaluated on single-phase CT angiography (sCTA). Target mismatch was defined as a CTP core volume ≤70 mL, mismatch ratio ≥1.8, and absolute mismatch volume ≥15 mL. Spearman correlation analysis and receiver operating characteristic curve analyses were performed.

RESULTS

The median NCCT ASPECTS of the 164 patients was 8 (IQR 6-9), median sCTA-CS was 2 (IQR 1-2), and median CTP core volume was 8 mL (IQR 0-29.5). There was a strong correlation between NCCT ASPECTS and CTP core volume (rs=-0.756, p<0.0001) and a moderate correlation between the sCTA-CS and CTP core volume (rs=-0.450, p<0.0001). Integrating NCCT ASPECTS and sCTA-CS provided a higher area under the curve (AUC) for predicting target mismatch (AUC=0.882; sensitivity, 89.1%; specificity, 77.8%; p<0.001).

CONCLUSIONS

NCCT ASPECTS had a strong correlation with CTP core volumes in patients with LVO-AIS in delayed time windows. Combining NCCT ASPECTS with sCTA-CS resulted in a more accurate prediction of target mismatch. If a CTP scan is not available, NCCT ASPECTS combined with sCTA-CS may guide clinicians in making treatment decisions.

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.

Cerebral hemodynamics in symptomatic anterior circulation intracranial stenosis measured by angiography-based quantitative flow ratio: association with CT perfusion

OBJECTIVES

Cerebral hemodynamics is important for the management of intracranial atherosclerotic stenosis (ICAS). This study aimed to determine the utility of angiography-based quantitative flow ratio (QFR) to reflect cerebral hemodynamics in symptomatic anterior circulation ICAS by evaluating its association with CT perfusion (CTP).

METHODS

Sixty-two patients with unilateral symptomatic stenosis in the intracranial internal carotid artery or middle cerebral artery who received percutaneous transluminal angioplasty (PTA) or PTA with stenting were included. Murray law-based QFR (μQFR) was computed from a single angiographic view. CTP parameters including cerebral blood flow, cerebral blood volume, mean transit time (MTT), and time to peak (TTP) were calculated, and relative values were obtained as the ratio between symptomatic and contralateral hemispheres. Relationships between μQFR and perfusion parameters, and between μQFR and perfusion response after intervention, were analyzed.

RESULTS

Thirty-eight patients had improved perfusion after treatment. μQFR was significantly correlated with relative values of TTP and MTT, with correlation coefficients of  -0.45 and  -0.26, respectively, on a per-patient basis, and  -0.72 and  -0.43, respectively, on a per-vessel basis (all p < 0.05). Sensitivity and specificity for μQFR to diagnose hypoperfusion at a cut-off value of 0.82 were 94.1% and 92.1%, respectively. Multivariate analysis revealed that μQFRpost (adjusted odds ratio [OR], 1.48; p = 0.002), collateral score (adjusted OR, 6.97; p = 0.01), and current smoking status (adjusted OR, 0.03; p = 0.01) were independently associated with perfusion improvement after treatment.

CONCLUSIONS

μQFR was associated with CTP in patients with symptomatic anterior circulation ICAS and may be a potential marker for real-time hemodynamic evaluation during interventional procedures.

KEY POINTS

• Murray law-based QFR (μQFR) is associated with CT perfusion parameters in intracranial atherosclerotic stenosis and can differentiate hypoperfusion from normal perfusion. • Post-intervention μQFR, collateral score, and current smoking status are independent factors associated with improved perfusion after treatment.

Development and Validation of a Postprocedural Model to Predict Outcome After Endovascular Treatment for Ischemic Stroke

Importance

Outcome prediction after endovascular treatment (EVT) for ischemic stroke is important to patients, family members, and physicians.

Objective

To develop and validate a model based on preprocedural and postprocedural characteristics to predict functional outcome for individual patients after EVT.

Design, Setting, and Participants

A prediction model was developed using individual patient data from 7 randomized clinical trials, performed between December 2010 and December 2014. The model was developed within the Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials (HERMES) collaboration and external validation in data from the Dutch Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN) Registry of patients treated in clinical practice between March 2014 and November 2017. Participants included patients from multiple centers throughout different countries in Europe, North America, East Asia, and Oceania (derivation cohort), and multiple centers in the Netherlands (validation cohort). Included were adult patients with a history of ischemic stroke from an intracranial large vessel occlusion in the anterior circulation who underwent EVT within 12 hours of symptom onset or last seen well. Data were last analyzed in July 2022.

Main Outcome(s) and Measure(s)

A total of 19 variables were assessed by multivariable ordinal regression to predict functional outcome (modified Rankin Scale [mRS] score) 90 days after EVT. Variables were routinely available 1 day after EVT. Akaike information criterion (AIC) was used to optimize model fit vs model complexity. Probabilities for functional independence (mRS 0-2) and survival (mRS 0-5) were derived from the ordinal model. Model performance was expressed with discrimination (C statistic) and calibration.

Results

A total of 781 patients (median [IQR] age, 67 [57-76] years; 414 men [53%]) constituted the derivation cohort, and 3260 patients (median [IQR] age, 72 [61-80] years; 1684 men [52%]) composed the validation cohort. Nine variables were included in the model: age, baseline National Institutes of Health Stroke Scale (NIHSS) score, prestroke mRS score, history of diabetes, occlusion location, collateral score, reperfusion grade, NIHSS score at 24 hours, and symptomatic intracranial hemorrhage 24 hours after EVT. External validation in the MR CLEAN Registry showed excellent discriminative ability for functional independence (C statistic, 0.91; 95% CI, 0.90-0.92) and survival (0.89; 95% CI, 0.88-0.90). The proportion of functional independence in the MR CLEAN Registry was systematically higher than predicted by the model (41% vs 34%), whereas observed and predicted survival were similar (72% vs 75%). The model was updated and implemented for clinical use.

Conclusion and relevance

The prognostic tool MR PREDICTS@24H can be applied 1 day after EVT to accurately predict functional outcome for individual patients at 90 days and to provide reliable outcome expectations and personalize follow-up and rehabilitation plans. It will need further validation and updating for contemporary patients.

Predicting Penumbra Salvage and Infarct Growth in Acute Ischemic Stroke: A Multifactor Survival Game

BACKGROUND

Effective treatment of acute ischemic stroke requires reperfusion of salvageable tissue. We investigated the predictors of penumbra salvage (PS) and infarct growth (IG) in a large cohort of stroke patients.

METHODS

In the ASTRAL registry from 2003 to 2016, we selected middle cerebral artery strokes <24 h with a high-quality CT angiography and CT perfusion. PS and IG were correlated in multivariate analyses with clinical, biochemical and radiological variables, and with clinical outcomes.

RESULTS

Among 4090 patients, 551 were included in the study, 50.8% male, mean age (±SD) 66.3 ± 14.7 years, mean admission NIHSS (±SD 13.3 ± 7.1) and median onset-to-imaging-time (IQR) 170 (102 to 385) minutes. Increased PS was associated with the following: higher BMI and lower WBC; neglect; larger penumbra; absence of early ischemic changes, leukoaraiosis and other territory involvement; and higher clot burden score. Reduced IG was associated with the following: non-smokers; lower glycemia; larger infarct core; absence of early ischemic changes, chronic vascular brain lesions, other territory involvement, extracranial arterial pathology and hyperdense middle cerebral artery sign; and higher clot burden score. When adding subacute variables, recanalization was associated with increased PS and reduced IG, and the absence of haemorrhage with reduced IG. Collateral status was not significantly associated with IG nor with PS. Increased PS and reduced IG correlated with better 3- and 12-month outcomes.

CONCLUSION

In our comprehensive analysis, multiple factors were found to be responsible for PS or IG, the strongest being radiological features. These findings may help to better select patients, particularly for more aggressive or late acute stroke treatment.

Automated LVO detection and collateral scoring on CTA using a 3D self-configuring object detection network: a multi-center study

The use of deep learning (DL) techniques for automated diagnosis of large vessel occlusion (LVO) and collateral scoring on computed tomography angiography (CTA) is gaining attention. In this study, a state-of-the-art self-configuring object detection network called nnDetection was used to detect LVO and assess collateralization on CTA scans using a multi-task 3D object detection approach. The model was trained on single-phase CTA scans of 2425 patients at five centers, and its performance was evaluated on an external test set of 345 patients from another center. Ground-truth labels for the presence of LVO and collateral scores were provided by three radiologists. The nnDetection model achieved a diagnostic accuracy of 98.26% (95% CI 96.25-99.36%) in identifying LVO, correctly classifying 339 out of 345 CTA scans in the external test set. The DL-based collateral scores had a kappa of 0.80, indicating good agreement with the consensus of the radiologists. These results demonstrate that the self-configuring 3D nnDetection model can accurately detect LVO on single-phase CTA scans and provide semi-quantitative collateral scores, offering a comprehensive approach for automated stroke diagnostics in patients with LVO.

Endovascular treatment versus no endovascular treatment after 6-24 h in patients with ischaemic stroke and collateral flow on CT angiography (MR CLEAN-LATE) in the Netherlands: a multicentre, open-label, blinded-endpoint, randomised, controlled, phase 3 trial

BACKGROUND

Endovascular treatment for anterior circulation ischaemic stroke is effective and safe within a 6 h window. MR CLEAN-LATE aimed to assess efficacy and safety of endovascular treatment for patients treated in the late window (6-24 h from symptom onset or last seen well) selected on the basis of the presence of collateral flow on CT angiography (CTA).

METHODS

MR CLEAN-LATE was a multicentre, open-label, blinded-endpoint, randomised, controlled, phase 3 trial done in 18 stroke intervention centres in the Netherlands. Patients aged 18 years or older with ischaemic stroke, presenting in the late window with an anterior circulation large-vessel occlusion and collateral flow on CTA, and a neurological deficit score of at least 2 on the National Institutes of Health Stroke Scale were included. Patients who were eligible for late-window endovascular treatment were treated according to national guidelines (based on clinical and perfusion imaging criteria derived from the DAWN and DEFUSE-3 trials) and excluded from MR CLEAN-LATE enrolment. Patients were randomly assigned (1:1) to receive endovascular treatment or no endovascular treatment (control), in addition to best medical treatment. Randomisation was web based, with block sizes ranging from eight to 20, and stratified by centre. The primary outcome was the modified Rankin Scale (mRS) score at 90 days after randomisation. Safety outcomes included all-cause mortality at 90 days after randomisation and symptomatic intracranial haemorrhage. All randomly assigned patients who provided deferred consent or died before consent could be obtained comprised the modified intention-to-treat population, in which the primary and safety outcomes were assessed. Analyses were adjusted for predefined confounders. Treatment effect was estimated with ordinal logistic regression and reported as an adjusted common odds ratio (OR) with a 95% CI. This trial was registered with the ISRCTN, ISRCTN19922220.

FINDINGS

Between Feb 2, 2018, and Jan 27, 2022, 535 patients were randomly assigned, and 502 (94%) patients provided deferred consent or died before consent was obtained (255 in the endovascular treatment group and 247 in the control group; 261 [52%] females). The median mRS score at 90 days was lower in the endovascular treatment group than in the control group (3 [IQR 2-5] vs 4 [2-6]), and we observed a shift towards better outcomes on the mRS for the endovascular treatment group (adjusted common OR 1·67 [95% CI 1·20-2·32]). All-cause mortality did not differ significantly between groups (62 [24%] of 255 patients vs 74 [30%] of 247 patients; adjusted OR 0·72 [95% CI 0·44-1·18]). Symptomatic intracranial haemorrhage occurred more often in the endovascular treatment group than in the control group (17 [7%] vs four [2%]; adjusted OR 4·59 [95% CI 1·49-14·10]).

INTERPRETATION

In this study, endovascular treatment was efficacious and safe for patients with ischaemic stroke caused by an anterior circulation large-vessel occlusion who presented 6-24 h from onset or last seen well, and who were selected on the basis of the presence of collateral flow on CTA. Selection of patients for endovascular treatment in the late window could be primarily based on the presence of collateral flow.

FUNDING

Collaboration for New Treatments of Acute Stroke consortium, Dutch Heart Foundation, Stryker, Medtronic, Cerenovus, Top Sector Life Sciences & Health, and the Netherlands Brain Foundation.

Collaterals and Elusive Ischemic Penumbra

As alternative blood supply routes, collateral blood vessels can play a crucial role in determining patient outcomes in acute and chronic intracranial occlusive diseases. Studies have shown that increased collateral circulation can improve functional outcomes and reduce mortality, particularly in those who are not eligible for reperfusion therapy. This article aims to discuss the anatomy and physiology of collateral circulation, describe current imaging tools used to measure collateral circulation, and identify the factors that influence collateral status.

Pictorial Review on Imaging Findings in Cerebral CTP in Patients with Acute Stroke and Its Mimics: A Primer for General Radiologists

The imaging evaluation of computed tomography (CT), CT angiography (CTA), and CT perfusion (CTP) is of crucial importance in the setting of each emergency department for suspected cerebrovascular impairment. A fast and clear assignment of characteristic imaging findings of acute stroke and its differential diagnoses is essential for every radiologist. Different entities can mimic clinical signs of an acute stroke, thus the knowledge and fast identification of stroke mimics is important. A fast and clear assignment is necessary for a correct diagnosis and a rapid initiation of appropriate therapy. This pictorial review describes the most common imaging findings in CTP with clinical signs for acute stroke or other acute neurological disorders. The knowledge of these pictograms is therefore essential and should also be addressed in training and further education of radiologists.

Automated Collateral Scoring on CT Angiography of Patients with Acute Ischemic Stroke Using Hybrid CNN and Transformer Network

Collateral scoring plays an important role in diagnosis and treatment decisions of acute ischemic stroke (AIS). Most existing automated methods rely on vessel prominence and amount after vessel segmentation. The purpose of this study was to design a vessel-segmentation free method for automating collateral scoring on CT angiography (CTA). We first processed the original CTA via maximum intensity projection (MIP) and middle cerebral artery (MCA) region segmentation. The obtained MIP images were fed into our proposed hybrid CNN and Transformer model (MPViT) to automatically determine the collateral scores. We collected 154 CTA scans of patients with AIS for evaluation using five-folder cross validation. Results show that the proposed MPViT achieved an intraclass correlation coefficient of 0.767 (95% CI: 0.68-0.83) and a Kappa of 0.6184 (95% CI: 0.4954-0.7414) for three-point collateral score classification. For dichotomized classification (good vs. non-good and poor vs. non-poor), it also achieved great performance.

Mechanical thrombectomy in stroke patients of advanced age with score-based prediction of outcome

BACKGROUND

Stroke patients ≥80 years constituted only 15% in randomised trials on mechanical thrombectomy (MT), but is a considerable higher proportion in clinical practice. Association of clinical variables collected before MT with functional outcome has not been independently described in these patients, while being important in the decision of patient eligibility for MT.

METHODS

We included patients consecutively at a single centre (2017-2021) categorised as octogenarians (age: 80-89 years) or nonagenarians (age: 90-99 years). Functional outcome at 90 days was defined as fair (modified Rankin Scale (mRS) 0-3) or poor (mRS 4-6). Clinical variables collected before MT were analysed for association with shift of mRS in a poor direction. Significant predictors were used to produce a risk score of fair outcome. Significance was set at the p < 0.05 level.

RESULTS

Nonagenarians (n = 43, 15.5%) compared to octogenarians (n = 235, 84.5%) less likely achieved fair outcome (20.9% vs. 46.0%, p < 0.01) with higher mortality (65.1% vs. 31.9%, p < 0.01). Significant predictors of outcome were: age, adjusted odds ratio (aOR) = 0.91 (95% confidence interval (CI): 0.86-0.97); pre-stroke mRS, aOR = 0.57 (95% CI: 0.44-0.73); National Institute of Health Stroke Scale at admission, aOR = 0.91 (95% CI: 0.87-0.95); Alberta Stroke Program Early Computed Tomography, aOR = 1.23 (95% CI: 1.05-1.45). After bootstrap validation, the area under the curve of the risk score was 0.74 and the optimal cut-off for fair outcome was a score of >7 points.

CONCLUSIONS

One in two octogenarians achieved fair outcome, however, only one in five nonagenarians had fair outcome. The clinical risk score could be considered as guidance when deciding patient eligibility for MT.

Timing and causes of death after endovascular thrombectomy in patients with acute ischemic stroke

Introduction:

Endovascular thrombectomy (EVT) increases the chance of good functional outcome after ischemic stroke caused by a large vessel occlusion, but the risk of death in the first 90 days is still considerable. We assessed the causes, timing and risk factors of death after EVT to aid future studies aiming to reduce mortality.

Patients and methods:

We used data from the MR CLEAN Registry, a prospective, multicenter, observational cohort study of patients treated with EVT in the Netherlands between March 2014, and November 2017. We assessed causes and timing of death and risk factors for death in the first 90 days after treatment. Causes and timing of death were determined by reviewing serious adverse event forms, discharge letters, or other written clinical information. Risk factors for death were determined with multivariable logistic regression.

Results:

Of 3180 patients treated with EVT, 863 (27.1%) died in the first 90 days. The most common causes of death were pneumonia (215 patients, 26.2%), intracranial hemorrhage (142 patients, 17.3%), withdrawal of life-sustaining treatment because of the initial stroke (110 patients, 13.4%) and space-occupying edema (101 patients, 12.3%). In total, 448 patients (52% of all deaths) died in the first week, with intracranial hemorrhage as most frequent cause. The strongest risk factors for death were hyperglycemia and functional dependency before the stroke and severe neurological deficit at 24–48 h after treatment.

Discussion and conclusion:

When EVT fails to decrease the initial neurological deficit, strategies to prevent complications like pneumonia and intracranial hemorrhage after EVT could improve survival, as these are often the cause of death.

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.

Collateral status, hyperglycemia, and functional outcome after acute ischemic stroke

BACKGROUND

Mixed data exist regarding the association between hyperglycemia and functional outcome after acute ischemic stroke when accounting for the impact of leptomeningeal collateral flow. We sought to determine whether collateral status modifies the association between treatment group and functional outcome in a subset of patients with large vessel occlusion enrolled in the Stroke Hyperglycemia Insulin Network Effort (SHINE) trial.

METHODS

In this post-hoc analysis, we analyzed patients enrolled into the SHINE trial with anterior circulation large vessel occlusion who underwent imaging with CT angiography prior to glucose control treatment group assignment. The primary analysis assessed the degree to which collateral status modified the effect between treatment group and functional outcome as defined by the 90-day modified Rankin Scale score. Logistic regression was used to model the data, with adjustments made for thrombectomy status, age, post-perfusion thrombolysis in cerebral infarction (TICI) score, tissue plasminogen activator (tPA) use, and baseline National Institutes of Health Stroke Scale (NIHSS) score. Five SHINE trial centers contributed data for this analysis. Statistical significance was defined as a p-value < 0.05.

RESULTS

Among the 1151 patients in the SHINE trial, 57 with angiographic data were included in this sub-analysis, of whom 19 had poor collaterals and 38 had good collaterals. While collateral status had no effect (p = 0.855) on the association between glucose control treatment group and functional outcome, patients with good collaterals were more likely to have a favorable functional outcome (p = 0.001, OR 5.02; 95% CI 1.37-16.0).

CONCLUSIONS

In a post-hoc analysis using a subset of patients with angiographic data enrolled in the SHINE trial, collateral status did not modify the association between glucose control treatment group and functional outcome. However, consistent with prior studies, there was a significant association between good collateral status and favorable outcome in patients with large vessel occlusion stroke.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier is NCT01369069. Registration date is June 8, 2011.

Quantitative collateral score for the prediction of clinical outcomes in stroke patients: Better than visual grading

Objectives

To identify preoperative prognostic factors for acute ischemic stroke (AIS) patients receiving mechanical thrombectomy (MT) and compare the performance of quantitative collateral score (qCS) and visual collateral score (vCS) in outcome prediction.

Methods

Fifty-five patients with AIS receiving MT were retrospectively enrolled. qCS was defined as the percentage of the volume of collaterals of both hemispheres. Based on the dichotomous outcome assessed using a 90-day modified Rankin Scale (mRS), we compared qCS, vCS, age, sex, National Institute of Health stroke scale score, etiological subtype, platelet count, international normalized ratio, glucose levels, and low-density lipoprotein cholesterol (LDL-C) levels between favorable and unfavorable outcome groups. Logistic regression analysis was performed to determine the effect on the clinical outcome. The discriminatory power of qCS, vCS, and their combination with cofounders for determining favorable outcomes was tested with the area under the receiver-operating characteristic curve (AUC).

Results

vCS, qCS, LDL-C, and age could all predict clinical outcomes. qCS is superior over vCS in predicting favorable outcomes with a relatively higher AUC value (qCS vs. vCS: 0.81 vs. 0.74) and a higher sensitivity rate (qCS vs. vCS: 72.7% vs. 40.9%). The prediction power of qCS + LDL-C + age was best with an AUC value of 0.91, but the accuracy was just increased slightly compared to that of qCS alone.

Conclusion

Collateral scores, LDL-C and age were independent prognostic predictors for patients with AIS receiving MT; qCS was a better predictor than vCS. Furthermore, qCS + LDL-C + age offers a strong prognostic prediction power and qCS alone was another good choice for predicting clinical outcome.

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.

Basis and current state of computed tomography perfusion imaging: a review

Computed tomography perfusion (CTP) is a functional imaging that allows for providing capillary-level hemodynamics information of the desired tissue in clinics. In this paper, we aim to offer insight into CTP imaging which covers the basics and current state of CTP imaging, then summarize the technical applications in the CTP imaging as well as the future technological potential. At first, we focus on the fundamentals of CTP imaging including systematically summarized CTP image acquisition and hemodynamic parameter map estimation techniques. A short assessment is presented to outline the clinical applications with CTP imaging, and then a review of radiation dose effect of the CTP imaging on the different applications is presented. We present a categorized methodology review on known and potential solvable challenges of radiation dose reduction in CTP imaging. To evaluate the quality of CTP images, we list various standardized performance metrics. Moreover, we present a review on the determination of infarct and penumbra. Finally, we reveal the popularity and future trend of CTP imaging.

MR Angiography in Assessment of Collaterals in Patients with Acute Ischemic Stroke: A Comparative Analysis with Digital Subtraction Angiography

Collateral status has prognostic and treatment implications in acute ischemic stroke (AIS) patients. Unlike CTA, grading collaterals on MRA is not well studied. We aimed to evaluate the accuracy of assessing collaterals on pretreatment MRA in AIS patients against DSA. AIS patients with anterior circulation proximal arterial occlusion with baseline MRA and subsequent endovascular treatment were included. MRA collaterals were evaluated by two neuroradiologists independently using the Tan and Maas scoring systems. DSA collaterals were evaluated by using the American Society of Interventional and Therapeutic Neuroradiology grading system and were used as the reference for comparative analysis against MRA. A total of 104 patients met the inclusion criteria (59 female, age (mean ± SD): 70.8 ± 18.1). The inter-rater agreement (k) for collateral scoring was 0.49, 95% CI 0.37–0.61 for the Tan score and 0.44, 95% CI 0.26–0.62 for the Maas score. Total number (%) of sufficient vs. insufficient collaterals based on DSA was 49 (47%) and 55 (53%) respectively. Using the Tan score, 45% of patients with sufficient collaterals and 64% with insufficient collaterals were correctly identified in comparison to DSA, resulting in a poor agreement (0.09, 95% CI 0.1–0.28). Using the Maas score, only 4% of patients with sufficient collaterals and 93% with insufficient collaterals were correctly identified against DSA, resulting in poor agreement (0.03, 95% CI 0.06–0.13). Pretreatment MRA in AIS patients has limited concordance with DSA when grading collaterals using the Tan and Maas scoring systems.

Cerebral small vessel disease combined with cerebral collaterals to predict the prognosis of patients with acute large artery atherosclerotic stroke

Background and purpose

Besides cerebral collaterals, few studies have examined other additional factors affecting the prognosis of patients with large artery atherosclerotic (LAA) stroke. Our study aims to explore the effect of the cerebral small vessel disease (SVD) and the effects of its interaction with cerebral collaterals on the prognosis of patients with acute LAA stroke.

Method

Patients aged 18 years or older with LAA stroke within 24 h after stroke onset were consecutively enrolled. The functional outcome was determined using the modified Rankin Scale (mRS) at 3 months after stroke onset. Logistic multivariate analyses were used to identify the risk factors for stroke prognosis. Receiver operating characteristic (ROC) curves were constructed to compare the effects of cerebral collaterals and SVD on predicting the prognosis.

Results

Of the 274 enrolled patients, 174 (63.50%) were identified as having a favorable prognosis, and 100 (36.50%) were identified as having an unfavorable prognosis. After adjusting for covariates, the logistic regression analysis identified that unfavorable prognosis was related to the total SVD score (Model 1, adjusted odds ratio = 1.73, 95% CI: 1.15–2.61, P < 0.01; Model 2, adjusted odds ratio = 1.85, 95% CI: 1.23–2.79, P < 0.01) and Tan score (Model 1, adjusted odds ratio = 0.38, 95% CI: 0.23–0.64, P < 0.01; Model 2, adjusted odds ratio = 0.52, 95% CI: 0.33–0.82, P < 0.01). Compared with cerebral collaterals (AUC = 0.59; 95% CI: 0.52–0.67; P < 0.01) or SVD (AUC = 0.62; 95% CI: 0.56–0.69; P < 0.01) alone, the combination of collaterals and SVD (AUC = 0.66; 95% CI: 0.59–0.73; P < 0.01) had higher diagnostic value for an unfavorable prognosis, and the optimal sensitivity and specificity were 77.01 and 53.00%, respectively.

Conclusions

The total SVD burden was related to the prognosis of patients with LAA stroke. Compared with cerebral collaterals or SVD alone, cerebral collaterals combined with total SVD burden are better at predicting the prognosis of patients with acute LAA stroke.

Cerebral Collateral Circulation in the Era of Reperfusion Therapies for Acute Ischemic Stroke

Clinical outcomes of patients with acute ischemic stroke depend in part on the extent of their collateral circulation. A good collateral circulation has also been associated with greater benefit of intravenous thrombolysis and endovascular treatment. Treatment decisions for these reperfusion therapies are increasingly guided by a combination of clinical and imaging parameters, particularly in later time windows. Computed tomography and magnetic resonance imaging enable a rapid assessment of both the collateral extent and cerebral perfusion. Yet, the role of the collateral circulation in clinical decision-making is currently limited and may be underappreciated due to the use of rather coarse and rater-dependent grading methods. In this review, we discuss determinants of the collateral circulation in patients with acute ischemic stroke, report on commonly used and emerging neuroimaging techniques for assessing the collateral circulation, and discuss the therapeutic and prognostic implications of the collateral circulation in relation to reperfusion therapies for acute ischemic stroke.

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.

Comparison of the clinical value of transcranial Doppler ultrasound and computed tomography angiography for diagnosing ischemic cerebrovascular disease

Objective

To compare the clinical value of transcranial Doppler (TCD) ultrasound and computed tomography angiography (CTA) for diagnosing ischemic cerebrovascular disease.

Methods

A retrospective clinical study was conducted in 142 patients with ischemic cerebrovascular disease who were initially diagnosed by digital subtraction angiography. Under the single-blind condition, the patients were diagnosed by using TCD ultrasound and CTA independently. The accuracy of these two methods was compared.

Results

The accuracy of diagnosing bilateral middle cerebral artery, bilateral vertebral artery and bilateral internal carotid artery lesions with a TCD examination was significantly higher than that with a CTA examination. There were no significant differences in the accuracy of diagnosing bilateral anterior cerebral artery, bilateral posterior cerebral artery or basilar artery lesions between TCD ultrasound and CTA. The accuracy of diagnosing all cerebral arterial ischemic lesions was significantly higher with a TCD examination (87.39%) than with a CTA examination (69.75%). The accuracy of diagnosing all cerebral arteries that cause ischemic encephalopathy (cerebrovascular + cervical blood vessels) was significantly higher with a TCD examination (88.03%) than with a CTA examination (69.01%).

Conclusions

TCD ultrasound has several advantages over CTA. Therefore, TCD ultrasound is better for diagnosing ischemic encephalopathy than CTA.

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.

Sex Differences in Collateral Circulation and Outcome After Mechanical Thrombectomy in Acute Ischemic Stroke

Background

Collateral circulation is known to lead to smaller infarct volume and better functional outcome after mechanical thrombectomy (MT), but studies examining sex differences in collateral circulation are scarce. The aim of this study was to investigate if collateral circulation has a different impact on outcome in women and men.

Methods

A single-center retrospective study of 487 patients (230 men and 257 women) treated with MT for acute ischemic stroke in the anterior cerebral circulation. Collateral circulation was assessed on computed tomography angiography images. The outcome was evaluated at 90 days according to the modified Rankin Scale (mRS).

Results

Women were older, median age 76 years (IQR 68-83) vs. 71 years (IQR 63–78). Stroke severity and time to recanalization were comparable. More women had moderate or good collaterals in 58.4 vs. 47.0% for men (p = 0.01). Among patients with moderate and good collaterals significantly more men (61%) were functionally independent (mRS 0–2) than women (41.5%) (p = < 0.01). This difference remained significant after correcting for age by linear weighting, 60.4 vs. 46.8% (p = 0.03).

Conclusion

Women had better collateral flow but showed worse functional outcomes, while good collateral flow led to better outcomes in men, even after correcting for age. Further clinical studies on peri- and post-interventional care, factors affecting recovery after hospital discharge as well as basic research on the neurovascular unit are needed to find modifiable targets to improve clinical outcomes for women.

Beyond collaterals: brain frailty additionally improves prediction of clinical outcome in acute ischemic stroke

OBJECTIVES

We aimed to investigate the additional significance of cerebral small vessel disease (SVD) beyond collaterals in determining the clinical outcome after acute ischemic stroke (AIS).

METHODS

We retrospectively reviewed large vessel-involved stroke patients who had baseline CTA within 24 h after symptom onset and had an MRI scan 5 days after admission from October 1, 2018, to October 31, 2021. Collaterals and SVD markers (including atrophy, leukoaraiosis, lacunes, and perivascular space) were graded on CT angiography and MR images, respectively. Modified Rankin Scale (mRS) score at 90 days was recorded, and mRS ≤ 2 was regarded as a good clinical outcome. The associations between SVD markers, collaterals, and mRS were analyzed using logistic and causal mediation regression.

RESULTS

We finally enrolled 119 patients (70 ± 13 years). The multivariable regression showed atrophy (evidence: OR 0.05 [95% CI 0.01-0.31], p = 0.002; severe: OR 0.08 [95% CI 0.01-0.44], p = 0.007) and evidence of lacune (OR 0.30 [95% CI 0.08-0.96], p = 0.049) were associated with poor clinical outcomes after correcting covariables. Collaterals mediated 25.74% of the effect of atrophy on poor clinical outcomes (p < 0.001), while lacune impacted clinical outcomes without collaterals' mediation effect (p = 0.54). The classification model with atrophy and lacune had a significantly higher AUC than without markers to distinguish good and poor outcomes (p = 0.036).

CONCLUSIONS

Beyond collaterals, brain frailty, specifically assessed by atrophy and lacune, was essential in evaluating stroke patients and could additionally improve the stroke outcome prediction.

KEY POINTS

• Beyond collaterals, brain frailty, specifically assessed by brain atrophy and lacune, was still an independent risk factor of unfavorable clinical outcomes after AIS. • Adding brain atrophy and lacune into the model has an extra benefit in predicting stroke outcomes. • The effect of atrophy on stroke outcomes was proportionally mediated through collaterals, but about three-quarters of the effect of brain atrophy and the total effect of lacune directly impacted stroke outcomes without a mediation effect of collaterals.

Cerebral Hypoperfusion Intensity Ratio Is Linked to Progressive Early Edema Formation

The hypoperfusion intensity ratio (HIR) is associated with collateral status and reflects the impaired microperfusion of brain tissue in patients with acute ischemic stroke and large vessel occlusion (AIS-LVO). As a deterioration in cerebral blood flow is associated with brain edema, we aimed to investigate whether HIR is correlated with the early edema progression rate (EPR) determined by the ischemic net water uptake (NWU) in a multicenter retrospective analysis of AIS-LVO patients anticipated for thrombectomy treatment. HIR was automatically calculated as the ratio of time-to-maximum (TMax) > 10 s/(TMax) > 6 s. HIRs < 0.4 were regarded as favorable (HIR+) and ≥0.4 as unfavorable (HIR−). Quantitative ischemic lesion NWU was delineated on baseline NCCT images and EPR was calculated as the ratio of NWU/time from symptom onset to imaging. Multivariable regression analysis was used to assess the association of HIR with EPR. This study included 731 patients. HIR+ patients exhibited a reduced median NWU upon admission CT (4% (IQR: 2.1−7.6) versus 8.2% (6−10.4); p < 0.001) and less median EPR (0.016%/h (IQR: 0.007−0.04) versus 0.044%/h (IQR: 0.021−0.089; p < 0.001) compared to HIR− patients. Multivariable regression showed that HIR+ (β: 0.53, SE: 0.02; p = 0.003) and presentation of the National Institutes of Health Stroke Scale (β: 0.2, SE: 0.0006; p = 0.001) were independently associated with EPR. In conclusion, favorable HIR was associated with lower early edema progression and decreased ischemic edema formation on baseline NCCT.