Association of Collateral Status and Ischemic Core Growth in Patients With Acute Ischemic Stroke

Association of deep tiny flow voids with prognosis of acute middle cerebral artery atherosclerotic occlusion

Background

Deep tiny flow voids (DTFVs) have recently been identified as a novel form of collateral circulation linked to chronic steno-occlusive atherosclerotic middle cerebral artery (MCA) lesions, detectable via high-resolution magnetic resonance imaging (HR-MRI). To date, no study has focused on the presence and clinical significance of DTFVs in acute MCA atherosclerotic occlusion.

Materials and methods

This retrospective study included patients with acute MCA atherosclerotic occlusion from two multicenter HR-MRI cohorts. The incidence of DTFVs and its association with baseline National Institute of Health Stroke Scale (NIHSS) scores, infarct volume, and the proportion of patients with a favorable 90-day clinical outcome defined as a modified Rankin Scale (mRS) ≤ 2 were analyzed.

Results

Sixty-six patients (mean age 58.2 ± 9.2 years; 71.2% men) were included. The median time from stroke onset to image was 44.5 (27.3-67.0) hours. DTFVs were identified in 57.6% of patients with MCA atherosclerotic occlusion. After adjusting the potential confounders, DTFVs were significantly associated with lower baseline NIHSS scores (β, -3.68; 95% CI, -6.30, -1.07; p = 0.007), smaller infarct volume (β, -40.88; 95% CI, -70.15, -11.60; p = 0.007), and a higher proportion of patients with favorable 90-day clinical outcome (OR, 6.03; 95% CI, 1.39-26.19; p = 0.017).

Conclusion

The presence of DTFVs was correlated with a favorable outcome in patients with acute MCA atherosclerotic occlusion. Improved recognition and awareness of this imaging marker of collaterals could help understand the varying infarct evolution seen in MCA occlusion and contribute to more individualized management and treatment.

The Los Angeles Motor Scale is independently associated with cerebral blood flow < 30% volume in large vessel occlusions

Background and PurposeMechanical thrombectomy (MT) is the treatment standard for large vessel occlusion (LVO) stroke. Under current guidelines, only patients with smaller ischemic core volumes (ICV) are eligible for MT. Thus, it is of interest to quickly estimate ICV in stroke patients. The Los Angeles Motor Scale (LAMS) is a validated tool used to assess stroke severity directly in the field. This study aims to determine whether LAMS score is also associated with ICV, as defined by the CBF <30% volume on CT perfusion imaging.MethodsWe performed a retrospective, multicenter cohort study of consecutive patients presenting with LVO stroke from 9/1/2017 to 10/1/2023. The inclusion criteria were patients with (1) stroke caused by large vessel occlusion confirmed on CTA and (2) diagnostically adequate, multimodal pretreatment CT imaging. Demographic, clinical, and imaging data was collected through manual chart review. Both univariate and multivariate analyses were applied to assess associations. A p-value <.05 was considered significant.ResultsA total of 283 patients (median age: 69, IQR: 61-78) were included in the study. On multivariate logistic regression analysis, we found that lower admission LAMS score (adjusted OR: 0.511, 95% CI: 0.313-0.834, p = .007) was independently associated with a CBF <30% volume of less than 50cc.ConclusionsAdmission LAMS is an independent predictor of a CBF <30% volume of less than 50cc. This demonstrates that LAMS can be used to estimate ICV, which will aid in the early triaging of LVO patients to thrombectomy-capable centers.

The prognostic value of the stress hyperglycemia ratio for all-cause mortality in stroke patients with diabetes or prediabetes

BACKGROUND

The stress hyperglycemia ratio (SHR), originally proposed in 2015 by Robert et al., is more significantly relevant and predictive of critical illness than absolute hyperglycemia. Several studies have validated the association between stress hyperglycemia ratio and cerebrovascular disease. However, the value of stress hyperglycemia ratio for severe stroke patients admitted to the ICU remains uncertain. The aim of this study was to investigate the relationship between stress hyperglycemia ratio and clinical short- and long-term prognosis of critically ill patients with acute ischemic stroke (AIS).

METHODS

Clinical data from 893 critically ill patients with ischemic stroke (IS) were extracted from the Medical Information Marketplace for Intensive Care (MIMIC-IV) database and 793 critically ill IS patients with 1 year of follow-up. The SHR is expressed by the formula: SHR = [(admission glucose (mg/dl)) / (28.7 × HbA1c (%) - 46.7)]. The study population was categorized into quartiles based on SHR level. Outcomes included ICU mortality, hospital mortality, and 1-year mortality. Cox proportional risk regression analysis and restricted cubic spline curves were used to elucidate the association between SHR and clinical prognosis in critically ill patients with AIS.

RESULTS

There were 69 ICU deaths and 100 in-hospital deaths in cohort 1, and 229 patients experienced all-cause mortality during the 1-year follow-up in cohort 2. Multivariate Cox proportional risk analysis showed that elevated SHR was significantly associated with an increased risk of hospital and 1-year all-cause mortality. After adjusting for confounders, patients with elevated SHR were significantly associated with hospital mortality (adjusted risk ratio, 1.870; 95 % confidence interval, 1.180-2.962; P = 0.008) and 1-year mortality (adjusted risk ratio, 2.325; 95 % confidence, 1.729-3.127; P < 0.001). Restricted cubic spline bars showed that a progressively increasing risk of all-cause mortality was associated with an elevated SHR.

CONCLUSION

Stress hyperglycemia ratios were significantly associated with in-hospital and 1-year all-cause mortality in critically ill IS patients. Moreover, we found that non-diabetic and prediabetic patients showed an increased risk of all-cause mortality. It is suggested that SHR may be useful in identifying ischemic stroke patients at high risk of all-cause mortality and providing personalized interventions as early as possible.

CTP-defined collaterals is a better predictor of intracranial atherosclerotic stenosis-related large-vessel occlusion than multiphase CTA-defined collaterals

The optimal neuroimaging modalities for differentiating intracranial atherosclerotic stenosis-related large vessel occlusion (ICAS-LVO) from embolism related LVO remain uncertain. This study aimed to address this question by directly comparing collateral circulation using either baseline CT perfusion (CTP) or multiphase CT angiogram (mCTA) to define collaterals. We retrospectively analyzed consecutive patients with acute large vessel occlusion from October 2021 to December 2023. All patients underwent CTP before endovascular therapy, and mCTA was reconstructed from CTP data. In-situ ICAS-LVO was confirmed by a neuro-interventional radiologist. Favorable collateral circulation was defined as a collateral index <0.4 on CTP or a collateral score ≥3 on mCTA. Of 377 patients, 72 (19%) had ICAS-LVO. Patients with only a collateral score ≥3 did not show significantly higher odds of ICAS-LVO (P = 0.681). In contrast, those with a collateral index <0.4 but not favorable mCTA collateral had higher odds of ICAS-LVO (OR2.69, 95%CI [1.07-7.01], P = 0.037). Subgroup analysis showed that a collateral grading scale ≥3 may not predict ICAS-LVO within 6 hours, whereas CTP's predictive performance remained consistently strong in both early and late windows. CTP defined favorable collaterals of collateral index <0.4 demonstrate greater predictive value for ICAS-LVO compared to mCTA, especially within an early time window.

Arterial Collaterals and Endovascular Treatment Effect in Acute Ischemic Stroke with Large Infarct: A Secondary Analysis of the TENSION Trial

Background Randomized clinical trials have demonstrated that endovascular thrombectomy reduces functional disability in patients with large ischemic stroke; arterial collateral status might be used to select these patients for endovascular thrombectomy. Purpose To investigate whether arterial collateral status modifies the treatment effect of endovascular thrombectomy in patients with large ischemic stroke. Materials and Methods The Efficacy and Safety of Thrombectomy in Stroke with Extended Lesion and Extended Time Window (TENSION) trial was a prospective, multicenter, randomized study investigating participants with acute large ischemic stroke due to anterior circulation large-vessel occlusion. Participants with an Alberta Stroke Program Early CT Score of 3-5 were enrolled at 41 participating centers between July 2018 and February 2023. Participants were randomly assigned to undergo either endovascular thrombectomy with best medical treatment or best medical treatment alone within 12 hours from stroke onset. Collateral status was graded on pretreatment single-phase CT angiography (CTA) images using the Tan score and dichotomized into poor (grade, 0-1) or good (grade, 2-3) based on the extent of collateral supply filling the affected middle cerebral artery territory. The primary outcome was the shift on the 90-day modified Rankin Scale (mRS). Results Of 253 randomized patients, 201 with pretreatment CTA were included (median age, 74 years; IQR, 66-80 years; 103 [51.2%] female patients; 103 [51.2%] patients underwent endovascular thrombectomy). Endovascular thrombectomy compared with best medical treatment (adjusted common odds ratio [OR], 3.69; 95% CI: 2.12, 6.54; P < .001) and good collaterals compared with poor collaterals (adjusted common OR, 2.88; 95% CI: 1.63, 5.11; P < .001) were independently associated with a shift in the 90-day mRS scores toward better functional outcomes. The treatment effect of endovascular thrombectomy over best medical treatment was not modified by collateral status (interaction, P = .88). The treatment effect of endovascular thrombectomy versus best medical treatment was found in patients with good collaterals (adjusted common OR, 3.93; 95% CI: 1.65, 9.69; P = .002) and poor collaterals (adjusted common OR, 3.92; 95% CI: 1.86, 8.52; P < .001). Conclusion In this secondary analysis of data from the TENSION trial, endovascular thrombectomy reduced 90-day functional disability compared with best medical treatment in patients with good and poor collaterals. These findings suggest that patients with large ischemic stroke manifesting within 12 hours after onset should undergo endovascular thrombectomy irrespective of single-phase CTA collateral status. ClinicalTrials.gov Identifier: NCT03094715 © RSNA, 2025 Supplemental material is available for this article. See also the editorial by Benomar and Raymond in this issue.

Clinical study of colorViz fusion image vascular grading based on multi-phase CTA reconstruction in acute ischemic stroke

OBJECTIVE

This study aimed to evaluate the diagnostic value of ColorViz fused images from multi-phase computed tomography angiography (mCTA) using GE Healthcare's FastStroke software for newly diagnosed cerebral infarctions in patients with acute ischemic stroke (AIS).

METHODS

A total of 106 AIS patients with unilateral anterior circulation occlusion were prospectively enrolled. All patients underwent mCTA scans during the arterial peak phase, venous peak phase, and venous late phase. The vascular information from these mCTA phases was combined into a time-varying color-coded image using GE Healthcare's FastStroke software. All participants also underwent magnetic resonance diffusion-weighted imaging (MR-DWI) within three days. The diagnostic capability of the mCTA ColorViz fusion images for identifying newly diagnosed intracranial infarction was assessed using MR-DWI as the gold standard, focusing on the degree of delayed vascular perfusion and the number of visible blood vessels.

RESULTS

The mCTA ColorViz fusion images revealed ischemic changes in brain tissue, demonstrating a sensitivity of 88.7% for superficial infarctions and 48.5% for deep infarctions. Additionally, the subjective vascular grading score of the mCTA ColorViz fusion images showed a strong negative correlation with the infarct area identified by MR-DWI (r = - 0.6, P < 0.001).

CONCLUSION

The mCTA ColorViz fusion images produced by FastStroke software provide valuable diagnostic insights for newly diagnosed cerebral infarction in AIS patients. The sensitivity of these images is notably higher for superficial infarctions compared to deep ones. This technique allows for relatively accurate detection of the ischemic extent and the likelihood of infarction in the superficial regions where lesions are located.

A novel NIR-II albumin-escaping probe for cerebral arteries and perfusion imaging in stroke mice model

In order to guide the formulation of post-stroke treatment strategy in time, it is necessary to have real-time feedback on collateral circulation and revascularization. Currently used near-infrared II (NIR-II) probes have inherent binding with endogenous albumin, resulting in significant background signals and uncontrollable pharmacokinetics. Therefore, the albumin-escaping properties of the new probe, IR-808AC, was designed, which achieved timely excretion and low background signal, enabling the short-term repeatable injection for visualization of cerebral vessels and perfusion. We further achieved continuous observation of changes in collateral vessels and perfusion during the 7-d period in middle cerebral artery occlusion mice using IR-808AC in vivo. Furthermore, using IR-808AC, we confirmed that remote ischemic conditioning could promote collateral vessels and perfusion. Finally, we evaluated the revascularization after thrombolysis on time in embolic stroke mice using IR-808AC. Overall, our study introduces a novel methodology for safe, non-invasive, and repeatable assessment of collateral circulation and revascularization in real-time that is crucial for the optimization of treatment strategies.

Safety and Efficacy of Thrombectomy in Vietnamese Stroke Patients Selected through Perfusion Imaging with an Onset Time between 6 and 24 Hours

INTRODUCTION

Recent trials have demonstrated the remarkable benefit of endovascular treatment (EVT) up to 24 h in patients with large vessel occlusion (LVO) and target mismatch profiles; however, benefits of late-window EVT in Vietnamese population remain poorly understood. This study aims to evaluate the real-world outcomes of EVT in acute ischemic stroke (AIS) patients selected using perfusion imaging within the 6-24-h window.

METHODS

This is a prospective study of consecutive patients with anterior circulation LVO stroke who underwent EVT within 6-24 h after last known well between August 2022 and March 2024. Patients were selected based on the DAWN/DEFUSE-3 criteria (Perfusion-RAPID, iSchemaView). The primary outcome was the proportion of patients with functional independence at 90 days (modified Rankin Scale score of 0-2). The secondary outcomes were successful reperfusion defined by thrombolysis in cerebral infarction (TICI) ≥2b on the final procedure and subgroup analysis between good (hypoperfusion intensity ratio [HIR] <0.4) and poor collaterals (HIR ≥0.4) groups. Safety outcomes were mortality rate and symptomatic intracranial hemorrhage (sICH).

RESULTS

Of 122 enrolled patients, 68% met inclusion criteria of DEFUSE-3 trial, 61% met DAWN trial criteria. Mean age was 66 years, median baseline NIHSS was 13, median time from stroke onset to hospital arrival was 12.55 h (9.50-16.48), and median infarct volume was 11.5 mL. The rate of functional independence at 90 days was 45.9%. Successful reperfusion (TICI score of ≥2b) was achieved by 83.6% of cases. The 90-day mortality rate was 10.7%; sICH was reported in 8 patients (6.6%). Patients with good collaterals had better functional outcome.

CONCLUSIONS

This real-world observational study suggests that late-window EVT may be safe and effective in eligible Vietnamese patients selected based on perfusion imaging, thus supporting its practical use in this patient population. HIR is a robust indicator of collateral status and could made it a valuable addition to stroke imaging workup in clinical setting.

A Minimalist Iron Oxide Nanoprobe for the High-Resolution Depiction of Stroke by Susceptibility-Weighted Imaging

The precise mapping of collateral circulation and ischemic penumbra is crucial for diagnosing and treating acute ischemic stroke (AIS). Unfortunately, there exists a significant shortage of high-sensitivity and high-resolution in vivo imaging techniques to fulfill this requirement. Herein, a contrast enhanced susceptibility-weighted imaging (CE-SWI) using the minimalist dextran-modified Fe3O4 nanoparticles (Fe3O4@Dextran NPs) are introduced for the highly sensitive and high-resolution AIS depiction under 9.4 T for the first time. The Fe3O4@Dextran NPs are synthesized via a simple one-pot coprecipitation method using commercial reagents under room temperature. It shows merits of small size (hydrodynamic size 25.8 nm), good solubility, high transverse relaxivity (r2) of 51.3 mM-1s-1 at 9.4 T, and superior biocompatibility. The Fe3O4@Dextran NPs-enhanced SWI can highlight the cerebral vessels readily with significantly improved contrast and ultrahigh resolution of 0.1 mm under 9.4 T MR scanner, enabling the clear spatial identification of collateral circulation in the middle cerebral artery occlusion (MCAO) rat model. Furthermore, Fe3O4@Dextran NPs-enhanced SWI facilitates the precise depiction of ischemia core, collaterals, and ischemic penumbra post AIS through matching analysis with other multimodal MR sequences. The proposed Fe3O4@Dextran NPs-enhanced SWI offers a high-sensitivity and high-resolution imaging tool for individualized characterization and personally precise theranostics of stroke patients.

The presence of a ghost infarct core is associated with fast core growth in acute ischemic stroke

INTRODUCTION

The overestimation of ischemic core volume by CT perfusion (CTP) is a critical concern in the selection of candidates for reperfusion therapy. This phenomenon is termed a ghost infarct core (GIC). Core growth rate (CGR) is an indicator of ischemic severity. We aimed to elucidate the association between GIC and CGR.

PATIENTS AND METHODS

Consecutive patients with acute ischemic stroke who underwent mechanical thrombectomy in our institute from March 2017 to July 2022 were enrolled. The initial ischemic core volume (IICV) was measured by pretreatment CTP, and the final infarct volume (FIV) was measured by diffusion-weighted imaging. A GIC was defined by IICV minus FIV > 10 ml. The CGR was calculated by dividing the IICV by the time from onset to CTP. Univariable analysis and a multivariable logistic regression model were used to evaluate the association between GIC-positive and CGR.

RESULTS

Of all 91 patients, 21 (23.1%) were GIC-positive. The GIC-positive group had higher CGR (14.2 [2.6-46.7] vs 4.8 [1.6-17.1] ml/h, p = 0.02) and complete recanalization (n = 15 (71.4%) vs 29 (41.4%), p = 0.02) compared to the GIC-negative group. On receiver-operating characteristic curve analysis, the optimal cutoff point of CGR to predict GIC-positive was 22 ml/h (sensitivity, 0.48; specificity, 0.85; AUC, 0.67). Multivariable logistic regression analysis showed that CGR ⩾ 22 ml/h (OR 6.44, 95% CI [1.59-26.10], p = 0.01) and complete recanalization (OR 3.72, 95% CI [1.14-12.08], p = 0.02) were independent predictors of GIC-positive.

CONCLUSIONS

A GIC was associated with fast CGR in acute ischemic stroke. Overestimation of the initial ischemic core may be determined by core growth speed.

Hypoperfusion Intensity Ratio and Hemorrhagic Transformation in Patients with Successful Recanalization after Thrombectomy

BACKGROUND AND PURPOSE

Hemorrhagic transformation remains a potentially devastating complication of acute ischemic stroke. We aimed to evaluate whether the hypoperfusion intensity ratio, a parameter derived from CT perfusion imaging, is associated with the development of hemorrhagic transformation in patients with anterior large-artery occlusion who had undergone thrombectomy.

MATERIALS AND METHODS

We retrospectively reviewed data from patients with consecutive acute ischemic strokes who had achieved successful recanalization (Thrombolysis in Cerebral Infarction score ≥2b) between January 2020 and December 2023. HIR was defined as the ratio of the volume of lesions with a time-to-maximum (Tmax) >6 seconds to those with a Tmax >10 second delay. The primary outcome, based on the European Cooperative Acute Stroke Study, was hemorrhagic transformation, diagnosed by follow-up imaging assessment in 24-hour windows, and radiologically classified as hemorrhagic infarction and parenchymal hematoma. The secondary outcome was a 3-month mRS score of ≥3.

RESULTS

Among 168 patients, 35 of 168 developed hemorrhagic transformation; 14 of 168 developed hemorrhagic infarction, and 21 of 168 developed parenchymal hematoma PH. After adjusting the latent covariates, increased hypoperfusion intensity ratio (per 0.1, adjusted OR [aOR] 1.68, 95% CI 1.26-2.25), ASPECTS (aOR 0.44, 95% CI 0.27-0.72), onset-to-puncture (aOR 1.01, 95% CI 1.00-1.02), and cardioembolism (aOR 5.6, 95% CI 1.59-19.7) were associated with hemorrhagic transformation in multivariable regression. The receiver operating characteristic curve indicated that hypoperfusion intensity ratio can predict hemorrhagic transformation accurately (area under the curve = 0.81; 95% CI, 0.738-0.882; P < .001) and predict parenchymal hematoma (area under the curve = 0.801; 95% CI, 0.727-0.875; P < .001).

CONCLUSIONS

Upon admission, hypoperfusion intensity ratio, an imaging parameter, predicted hemorrhagic transformation after reperfusion therapy in this patient population.

Hypoperfusion intensity ratio correlates with collaterals and predicts outcome and infarct volume in acute ischemic stroke patients

BACKGROUND

Hypoperfusion Intensity Ratio (HIR) is associated with collaterals and outcome in acute ischemic stroke (AIS). We investigated whether a combined assessment of HIR and collaterals could provide an added value.

METHODS

Retrospective single-center study, including AIS patients with large vessel occlusion and endovascular treatment 0-24 h from onset. Predictors of FIV and outcome (90 days modified Rankin Scale 0-1) were investigated with linear and logistic regression respectively. Subjects were stratified in three groups: poor collaterals (grade 0-3) with poor HIR (≥.4), good collaterals (grade 4-5) with poor HIR/poor collaterals with good HIR (<.4) and good collaterals with good HIR.

RESULTS

We included 337 patients (median age 77, 53.1% males), of whom 100 (29.7%) had excellent outcome. One hundred and forty five patients with favourable collateral and HIR profiles had smaller infarct (median poor collaterals with poor HIR 41 mL, good collaterals with poor HIR/poor collaterals with good HIR 21 mL and good collaterals with good HIR 11 mL, p <.001) and higher rates of excellent outcome (poor collaterals with poor HIR 15.7%, good collaterals with poor HIR/poor collaterals with good HIR 26.2% and good collaterals with good HIR 39.3% p =.001). Logistic regression showed that patients with favourable collateral and HIR profiles had the highest odds of good outcome (OR: 3.83, 95% CI 1.62-9.08, p =.002).

CONCLUSION

Collaterals and HIR are independent predictors of final infarct lesion and outcome in stroke patients and their integration provides an added value. These findings might inform clinical practice and future trials.

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.

Efficacy and safety of Ginkgolide with intravenous alteplase thrombolysis in acute ischemic stroke with large vessel occlusion: a subgroup analysis of GIANT

Aim

This study aims to explore the effectiveness and safety of Ginkgolide® in acute ischemic stroke (AIS) patients with large vessel occlusion (LVO) and moderate-to-severe stroke receiving intravenous alteplase thrombolysis (IVT).

Methods

Ginkgolide with Intravenous Alteplase Thrombolysis in Acute Ischemic Stroke Improving Neurological Function (GIANT) was an open-label, prospective, multicenter, cluster-randomized clinical trial and included AIS patients in 24 centers randomized to the intervention of intravenous Ginkgolide® or control group within the first 24 h after IVT. LVO was defined as any occlusion of the internal carotid artery, M1 or M2 of the middle cerebral artery, A1 or A2 of the anterior cerebral artery, P1 of the posterior cerebral artery, and V4 of the vertebral artery or the basilar artery. Stroke severity was assessed with the National Institutes of Health Stroke Scale (minor ≤5; moderate-to-severe >5). The primary outcome was a good outcome, defined as a modified Rankin Scale (mRS) score of 0-2 at 90 days. Secondary outcomes were early neurological improvement (ENI), defined as ≥18% increase in the National Institutes of Health Stroke Scale (NIHSS) score at 7 days compared to baseline and distribution of mRS at 3 months.

Results

A total of 1,113 patients were included, with 268/913 (29.4%) presenting LVO and 508 (45.6%) presenting moderate-to-severe stroke. In patients with LVO, Ginkgolide® usage was independently associated with ENI (P = 0.001) but not with a good outcome (P = 0.154). In the moderate-to-severe stroke subgroup, Ginkgolide® was independently associated with both a good outcome (P = 0.009) and ENI (P = 0.028). Ginkgolide® did not increase the risk of hemorrhagic transformation (all P > 0.05).

Conclusion

Using Ginkgolide® within 24-h after intravenous rt-PA is effective and safe in LVO and moderate-to-severe stroke patients.

Hypoperfusion Intensity Ratio as an Indirect Imaging Surrogate in Patients With Anterior Circulation Large-Vessel Occlusion and Association of Baseline Characteristics With Poor Collateral Status

BACKGROUND

Collateral status (CS) plays a crucial role in infarct growth rate, risk of postthrombectomy hemorrhage, and overall clinical outcomes in patients with acute ischemic stroke (AIS) secondary to anterior circulation large-vessel occlusions (LVOs). Hypoperfusion intensity ratio has been previously validated as an indirect noninvasive pretreatment imaging biomarker of CS. In addition to imaging, derangements in admission laboratory findings can also influence outcomes in patients with AIS-LVO. Therefore, our study aims to assess the relationship between admission laboratory findings, baseline characteristics, and CS, as assessed by hypoperfusion intensity ratio in patients with AIS-LVO.

METHODS AND RESULTS

In this retrospective study, consecutive patients presenting with AIS secondary to anterior circulation LVO who underwent pretreatment computed tomography perfusion were included. The computed tomography perfusion data processed by RAPID (Ischema View, Menlo Park, CA) generated the hypoperfusion intensity ratio. Binary logistic regression models were used to assess the relationship between patients' baseline characteristics, admission laboratory findings, and poor CS. A total of 221 consecutive patients with AIS-LVO between January 2017 and September 2022 were included in our study (mean±SD age, 67.0±15.8 years; 119 men [53.8%]). Multivariable logistic regression showed that patients with AIS caused by cardioembolic and cryptogenic causes (adjusted odds ratio [OR], 2.67; 95% CI, 1.20-5.97; P=0.016), those who presented with admission National Institutes of Health Stroke Scale score ≥12 (adjusted OR, 3.12; 95% CI, 1.61-6.04; P=0.001), and male patients (adjusted OR, 2.06; 95% CI, 1.13-3.77; P=0.018) were associated with poor CS.

CONCLUSIONS

Stroke caused by cardioembolic or cryptogenic causes, admission National Institutes of Health Stroke Scale score of ≥12, and male sex were associated with poor CS, as defined by hypoperfusion intensity ratio in the patients with AIS-LVO.

Quantitative evaluation of CTP derived time-density alterations versus CTP for collateral status prediction with stroke

BACKGROUND AND OBJECTIVES

Collateral status is a pivotal determinant of clinical outcomes in acute ischemic stroke (AIS); however, its evaluation can be challenging. We investigated the predictive value of CT perfusion (CTP) derived time and density alterations versus CTP for collateral status prediction in AIS.

METHODS

Consecutive patients with anterior circulation occlusion within 24 h were retrospectively included. Time-density curves of the CTP specified ischemic core, penumbra, and the corresponding contralateral unaffected brain were obtained. The collateral status was dichotomised into robust (4-5 scores) and poor (0-3 scores) using multiphase collateral scoring, as described by Menon et al.. Receiver operating characteristic curves and multivariable regression analysis were performed to assess the predictive ability of CTP-designated tissue time and density alterations, CTP for robust collaterals, and favourable outcomes (mRS score of 0-2 at 90 days).

RESULTS

One-hundred patients (median age, 68 years; interquartile range, 57-80 years; 61 men) were included. A smaller ischemic core, shorter peak time delay, lower peak density decrease, lower cerebral blood volume ratio, and cerebral blood flow ratio in the CTP specified ischemic core were significantly associated with robust collaterals (PFDR ≤ 0.004). The peak time delay demonstrated the highest diagnostic value (AUC, 0.74; P < 0.001) with 66.7 % sensitivity and 73.7 % specificity. Furthermore, the peak time delay of less than 8.5 s was an independent predictor of robust collaterals and favourable clinical outcomes.

CONCLUSIONS

Robust collateral status was significantly associated with the peak time delay in the ischemic core. It is a promising image marker for predicting collateral status and functional outcomes in AIS.

Hyperglycemia Is Associated With Computed Tomography Perfusion Core Volume Underestimation in Patients With Acute Ischemic Stroke With Large-Vessel Occlusion

Background

CT Perfusion (CTP) predictions of infarct core play an important role in the determination of treatment eligibility in large vessel occlusion (LVO) acute ischemic stroke (AIS). Prior studies have demonstrated that blood glucose can affect cerebral blood flow (CBF). Here we examine the influence of acute and chronic hyperglycemia on CTP estimations of infarct core.

Methods

From our prospectively collected multi-center observational cohort, we identified patients with LVO AIS who underwent CTP with RAPID (IschemaView, Stanford, CA) post-processing, followed by endovascular therapy with substantial reperfusion (TICI 2b-3) within 90 minutes, and final infarct volume (FIV) determination by MRI 48-72 hours post-treatment. Core volume over- and under-estimations were defined as a difference of at least 20 mL between CTP-RAPID predicted infarct core and DWI FIV. Primary outcome was the association of presentation glucose and HgbA1c with underestimation (UE) of core volume and was measured using multivariable logistic regression adjusted for comorbidities and presentation characteristics. Secondary outcomes included frequency of overestimation (OE) of infarct core.

Results

Among 256 patients meeting inclusion criteria, median age was 67 [IQR 57-77], 51.6% were female, and 132 (51.6%) and 93 (36.3%) had elevated presentation glucose and elevated HgbA1c, respectively. Median CTP-predicted core was 6 mL [IQR 0-30], median DWI FIV was 14 mL [IQR 6-43] and median difference was 12 mL [IQR 5-35]. Twenty-eight (10.9%) patients had infarct core OE and 68 (26.6%) had UE. Compared to those with no UE, patients with UE had elevated blood glucose (median 119 [103-155] vs 138 [117-195], p=0.002) and HgbA1c (median 5.80 [5.40-6.40] vs 6.40 [5.50-7.90], p=0.009). In multivariable analysis, UE was independently associated with elevated glucose (aOR 2.10, p=0.038) and HgbA1c (aOR 2.37, p=0.012). OE was associated with lower presentation blood glucose (median 109 [ 99-132] in OE vs 127 [107-172] in no OE, p=0.003) and HgbA1c (5.6 [IQR 5.1 - 6.2] in OE vs 5.90 [5.50-6.70] in no OE, p=0.012).

Conclusions

Acute and chronic hyperglycemia were strongly associated with CTP UE in patients with LVO AIS undergoing EVT. Glycemic state should be considered when interpreting CTP findings in patients with LVO AIS.

Lower admission stroke severity is associated with good collateral status in distal medium vessel occlusion stroke

BACKGROUND AND PURPOSE

Distal medium vessel occlusions (DMVOs) are a significant contributor to acute ischemic stroke (AIS), with collateral status (CS) playing a pivotal role in modulating ischemic damage progression. We aimed to explore baseline characteristics associated with CS in AIS-DMVO.

METHODS

This retrospective analysis of a prospectively collected database enrolled 130 AIS-DMVO patients from two comprehensive stroke centers. Baseline characteristics, including patient demographics, admission National Institutes of Health Stroke Scale (NIHSS) score, admission Los Angeles Motor Scale (LAMS) score, and co-morbidities, including hypertension, hyperlipidemia, diabetes, coronary artery disease, atrial fibrillation, and history of transient ischemic attack or stroke, were collected. The analysis was dichotomized to good CS, reflected by hypoperfusion index ratio (HIR) <.3, versus poor CS, reflected by HIR ≥.3.

RESULTS

Good CS was observed in 34% of the patients. As to the occluded location, 43.8% occurred in proximal M2, 16.9% in mid M2, 35.4% in more distal middle cerebral artery, and 3.8% in distal anterior cerebral artery. In multivariate logistic analysis, a lower NIHSS score and a lower LAMS score were both independently associated with a good CS (odds ratio [OR]: 0.88, 95% confidence interval [CI]: 0.82-0.95, p < .001 and OR: 0.77, 95% CI: 0.62-0.96, p = .018, respectively). Patients with poor CS were more likely to manifest as moderate to severe stroke (29.1% vs. 4.5%, p < .001), while patients with good CS had a significantly higher chance of having a minor stroke clinically (40.9% vs. 12.8%, p < .001).

CONCLUSIONS

CS remains an important determinant in the severity of AIS-DMVO. Collateral enhancement strategies may be a worthwhile pursuit in AIS-DMVO patients with more severe initial stroke presentation, which can be swiftly identified by the concise LAMS and serves as a proxy for underlying poor CS.

Treatment with intravenous alteplase in ischaemic stroke patients with onset time between 4.5 and 24 hours (HOPE): protocol for a randomised, controlled, multicentre study

BACKGROUND

While intravenous thrombolysis is recommended for patients who had an acute ischaemic stroke (AIS) within 4.5 hours of symptom onset, there are few randomised trials investigating the benefits of thrombolysis beyond this therapeutic window.

AIM

To determine whether patients who had an AIS selected with the presence of potentially salvageable tissue on CT perfusion at 4.5-24 hours after stroke onset (for stroke with unknown onset time, the midpoint of the time last known to be well and symptom recognition time; for wake-up stroke, the midpoint of the time last known to be well or sleep onset and wake up time) will benefit from intravenous thrombolysis.

DESIGN

HOPE is a prospective, multicentre, randomised, open-label blinded endpoint trial with the stage of phase III. The treatment allocation employs 1:1 randomisation. The treatment arm under investigation is alteplase with standard therapy, the control arm is standard therapy. Eligibility imaging criteria include ischaemic core volume ≤70 mL, penumbra ≥10 mL and mismatch ≥20%.

STUDY OUTCOMES

The primary outcome is non-disabled functional outcome (assessed as modified Rankin Scale score of 0-1 at 90 days).

DISCUSSION

HOPE is the first trial to investigate whether intravenous thrombolysis with alteplase offers benefits in patients who had an AIS presenting within 4.5-24 hours, which has the potential to extend time window and expand eligible population for thrombolysis therapy.

CT perfusion for predicting intracranial atherosclerotic middle cerebral artery occlusion

Backgrounds and purpose

Identifying the underlying cause of acute middle cerebral artery occlusion (MCAO) as intracranial atherosclerotic stenosis (ICAS) or embolism is essential for determining the optimal treatment strategy before endovascular thrombectomy. We aimed to evaluate whether baseline computed tomography perfusion (CTP) characteristics could differentiate ICAS-related MCAO from embolic MCAO.

Methods

We conducted a retrospective analysis of the clinical and baseline CTP data from patients who underwent endovascular thrombectomy for acute MCAO between January 2018 and December 2022. Core volume growth rate was defined as core volume on CTP divided by onset to CTP time. Multivariate logistic analysis was utilized to identify independent predictors for ICAS-related acute MCAO, and the diagnostic performance of these predictors was evaluated using receiver operating characteristic curve analysis.

Results

Among the 97 patients included (median age, 71 years; 60% male), 31 (32%) were diagnosed with ICAS-related MCAO, and 66 (68%) had embolism-related MCAO. The ICAS group was younger (p = 0.002), had a higher proportion of males (p = 0.04) and smokers (p = 0.001), a lower prevalence of atrial fibrillation (AF) (p < 0.001), lower NIHSS score at admission (p = 0.04), smaller core volume (p < 0.001), slower core volume growth rate (p < 0.001), and more frequent core located deep in the brain (p < 0.001) compared to the embolism group. Multivariate logistic analysis identified core volume growth rate (aOR 0.46, 95% CI 0.26-0.83, p = 0.01) as an independent predictor of ICAS-related MCAO. A cutoff value of 2.5 mL/h for core volume growth rate in predicting ICAS-related MCAO was determined from the receiver operating characteristic curve analysis, with a sensitivity of 81%, specificity of 80%, positive predictive value of 66%, and negative predictive value of 90%.

Conclusion

Slow core volume growth rate identified on baseline CTP can predict ICAS-related MCAO. Further prospective studies are warranted to confirm and validate these findings.

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.

The predictive value of serum F-actin on the severity and early neurological deterioration of acute ischemic stroke: Predictive value of F-actin in stroke

BACKGROUND

F-actin is involved in the progression of ischemic stroke and is associated with the disruption of the blood-brain barrier. In this article, we evaluated serum F-actin as a biomarker in stroke severity and early neurological deterioration (END) in acute ischemic stroke.

METHODS

In this study, serum F-actin was measured in consecutively collected 140 AIS patients and 144 healthy controls matched in gender and age by ELISA. Early neurological deterioration (END) was defined as the deterioration of neurological dysfunction within 72 hours of admission, with an increase of ≥ 4 points in the NIHSS score. Severe stroke was defined as a NIHSS score>8 at admission.

RESULTS

The serum F-actin level in AIS was significantly higher than healthy controls (p = 0.041). In large-artery atherosclerosis stroke and cardioembolic stroke, serum F-actin were significantly higher than that in small artery occlusion stroke (padjust = 0.019, padjust < 0.001, respectively).F-actin level above the critical value (>1.37 µg/L) was significantly associated with severe stroke (OR, 3.015; 95 %CI, 1.014-8.963; p = 0.047) . In addition, elevated level of F-actin was significantly associated with END (OR, 1.323; 95 % CI, 1.001-1.747, p = 0.049). When the level of F-actin was above the critical value (>2.17 µg/L), its association with END remained significant (OR, 6.303; 95 %CI, 2.160-18.394; p < 0.001) .

CONCLUSION

F-actin is an important blood biomarker in the early stage of AIS, and high levels of F-actin are valuable in determining the severity of stroke and predicting early neurological deterioration.

Factors Contributing to Rapid Early Infarct Expansion in Acute Ischemic Stroke Patients With Large Vessel Occlusion

Background Acute ischemic stroke, particularly in cases involving large vessel occlusion (LVO), poses a significant challenge due to the potential for rapid infarct expansion in the early phase. Such expansion, if not managed promptly, can lead to severe neurological deficits and poor clinical outcomes. Understanding the contributing factors that accelerate early infarct expansion is crucial for optimizing treatment strategies and improving patient prognosis. The main aim of the study is to determine the factors contributing to rapid early infarct expansion in acute ischemic stroke patients with LVO. Methodology The retrospective study was conducted at Liaquat National Hospital in Karachi from August 2023 to December 2023. Data were collected from 685 patients with anterior circulation LVO-related acute stroke with witnessed stroke onset and baseline perfusion imaging. Extracted clinical data included age, gender, medical history (hypertension, diabetes, etc.), and baseline National Institutes of Health Stroke Scale (NIHSS) scores. Results The mean age of the included patients was 67.4 years, with a relatively balanced gender distribution, i.e., 48.5% male (n = 332) and 51.5% female (n = 353). The mean baseline NIHSS score was 14.2, reflecting initial neurological severity. Imaging parameters revealed that 294 (42.6%) patients exhibited infarct expansion, with an average penumbra size of 23.5 mL. Hypoperfusion intensity ratio (HIR) quartiles demonstrated a notable association with progression rates, escalating from 27 (4%) patients in the first quartile to approximately 527 (77%) patients in the fourth quartile, highlighting a significant correlation between HIR and infarct expansion (p < 0.001). Conclusions HIR emerged as a pivotal factor strongly associated with rapid infarct expansion, underscoring its significance in predicting the trajectory of ischemic injury.

Global hyperperfusion after successful endovascular thrombectomy is linked to worse outcome in acute ischemic stroke

Patients with stroke may develop hyperperfusion after a successful endovascular thrombectomy (EVT). However, the relationship between post-EVT hyperperfusion and clinical outcomes remains unclear and requires further clarification. We reviewed consecutive patients with anterior circulation occlusion who were successfully recanalized with EVT. Based on post-EVT arterial spin-labeling images, hyperperfusion was categorized as follows: global hyperperfusion (GHP), increased cerebral blood flow (CBF) in ≥ 50% of the culprit vessel territory; focal hyperperfusion (FHP), increased CBF in < 50% of the culprit vessel territory; no hyperperfusion (NHP), no discernible CBF increase. Factors associated with hyperperfusion were assessed, and clinical outcomes were compared among patients under different hyperperfusion categories. Among 131 patients, 25 and 40 patients developed GHP and FHP, respectively. Compared to other groups, the GHP group had worse National Institutes of Health Stroke Scale score (GHP vs. NHP/FHP, 18.1 ± 7.4 vs. 12.3 ± 6.0; p < 0.001), a larger post-EVT infarct volume (98.9 [42.3-132.7] vs. 13.5 [5.0-34.1] mL; p < 0.001), and a worse 90-day outcome (modified Rankin Scale, 3 [1-4] vs. 2 [0-3]; p = 0.030). GHP was independently associated with infarct volume (B = 0.532, standard error = 0.163, p = 0.001), and infarct volume was a major mediator of the association of GHP with unfavorable outcomes (total effect: β = 0.176, p = 0.034; direct effect: β = 0.045, p = 0.64; indirect effect: β = 0.132, p = 0.017). Patients presenting with post-EVT GHP had poorer neurological prognosis, which is likely mediated by a large infarct volume.

Pericarotid Fat Stranding at Computed Tomography Angiography: A Marker of the Short-Term Prognosis of Acute Ischemic Stroke

PURPOSE

Perivascular epicardial fat stranding detected in the coronary computed tomography (CT) angiography is associated with culprit lesions and provides helpful information on the risk of acute coronary syndrome. This study aimed to evaluate the potential clinical significance of pericarotid fat stranding (PCFS) and investigate the association between PCFS and short-term prognosis in acute stroke using head and neck CT angiography (CTA).

METHODS

This study included 80 patients (mean age, 69.69 ± 11.03; 58 men) who underwent both head and neck CTA and magnetic resonance imaging within a 1-week period. Baseline characteristics, pericarotid adipose tissue attenuation, plaque characteristics, ischemic penumbra, infarct core volume, infarct core growth rate (CGR), and the grade of collateral status were recorded and compared between a PCFS group and a non-PCFS group. Data were compared using the 2-sample t test, Mann-Whitney U test, Fisher exact test, and Spearman rank correlation analysis.

RESULTS

We found that patients with PCFS had a significantly higher pericarotid adipose tissue density than patients without PCFS (-55.75 ± 5.53 vs -65.82 ± 9.65, P < 0.001). Patients with PCFS showed a larger infarct core volume (166.43 ± 73.07 vs 91.43 ± 55.03, P = 0.001) and faster CGR (39.57 ± 12.01 vs 19.83 ± 32.77; P < 0.001), and the frequency of adverse prognosis was more significant than in control participants (83.33% vs 19.11%).

CONCLUSIONS

Individuals with PCFS showed higher CGR, which was substantially related to worse outcomes in patients with acute stroke with ipsilateral carotid atherosclerosis. Recognition of PCFS may help predict stroke prognosis and allow doctors to take early action to improve patient prognosis.

Nomogram to Predict 90-Day All-Cause Mortality in Acute Ischemic Stroke Patients after Endovascular Thrombectomy

OBJECTIVE

Although Endovascular Thrombectomy (EVT) significantly improves the prognosis of Acute Ischemic Stroke (AIS) patients with large vessel occlusion, the mortality rate remains higher. This study aimed to construct and validate a nomogram for predicting 90-day all-cause mortality in AIS patients with large vessel occlusion and who have undergone EVT.

METHODS

AIS patients with large vessel occlusion in the anterior circulation who underwent EVT from May 2017 to December 2022 were included. 430 patients were randomly split into a training group (N=302) and a test group (N=128) for the construction and validation of our nomogram. In the training group, multivariate logistic regression analysis was performed to determine the predictors of 90-day all-cause mortality. The C-index, calibration plots, and decision curve analysis were applied to evaluate the nomogram performance.

RESULTS

Multivariate logistic regression analysis revealed neurological deterioration during hospitalization, age, baseline National Institutes of Health Stroke Scale (NIHSS) score, occlusive vessel location, malignant brain edema, and Neutrophil-to-lymphocyte Ratio (NLR) as the independent predictors of 90-day all-cause mortality (all p ≤ 0.039). The C-index of the training and test groups was 0.891 (95%CI 0.848-0.934) and 0.916 (95% CI: 0.865-0.937), respectively, showing the nomogram to be well distinguished. The Hosmer-Lemeshow goodness-of-fit test revealed the p-values for both the internal and external verification datasets to be greater than 0.5.

CONCLUSION

Our nomogram has incorporated relevant clinical and imaging features, including neurological deterioration, age, baseline NIHSS score, occlusive vessel location, malignant brain edema, and NLR ratio, to provide an accurate and reliable prediction of 90-day all-cause mortality in AIS patients undergoing EVT.

Core overestimation of CT perfusion in patients with cardiac insufficiency who had a stroke is mediated by impaired collaterals

BACKGROUND

We hypothesized that left ventricular systolic dysfunction (LVSD) would lead to an ischemic core overestimation in patients with acute ischemic stroke (AIS), and impaired collateral status might partly mediate this effect.

OBJECTIVE

A pixel-based analysis of CT perfusion (CTP) and follow-up CT was undertaken to investigate the optimum CTP thresholds for the ischemic core if overestimation was found.

METHODS

A total of 208 consecutive patients with AIS with large vessel occlusion in the anterior circulation, who received initial CTP evaluation and successful reperfusion, were retrospectively analyzed and divided into an LVSD (left ventricular ejection fraction (LVEF) ratio <50%; n=40) and a normal cardiac function (LVEF≥50%; n=168) group. Ischemic core overestimation was considered when the CTP-derived core was larger than the final infarct volume. We investigated the relationship between cardiac function, probability for core overestimation, and collateral scores using mediation analysis. A pixel-based analysis was undertaken to define the optimum CTP thresholds for ischemic core.

RESULTS

LVSD was independently associated with impaired collaterals (aOR=4.28, 95% CI 2.01 to 9.80, P<0.001) and core overestimation (aOR=2.52, 95% CI 1.07 to 5.72, P=0.030). In mediation analysis, the total effect on core overestimation is composed of the direct effect of LVSD (+17%, P=0.034) and the mediated indirect effect of collateral status (+6%, P=0.020). Collaterals explained 26% of the effect of LVSD on core overestimation. Compared with relative cerebral blood flow (rCBF) thresholds of <35%, <30%, and <20%, a rCBF <25% cut-off point had the highest correlation (r=0.91) and best agreement (mean difference 3.2±7.3 mL) with the final infarct volume to determine the CTP-derived ischemic core in patients with LVSD.

CONCLUSIONS

LVSD increased the possibility of ischemic core overestimation on baseline CTP, partly due to impaired collateral status, and a stricter rCBF threshold should be considered.

Factors Associated With Fast Early Infarct Growth in Patients With Acute Ischemic Stroke With a Large Vessel Occlusion

BACKGROUND AND OBJECTIVES

The optimal methods for predicting early infarct growth rate (EIGR) in acute ischemic stroke with a large vessel occlusion (LVO) have not been established. We aimed to study the factors associated with EIGR, with a focus on the collateral circulation as assessed by the hypoperfusion intensity ratio (HIR) on perfusion imaging, and determine whether the associations found are consistent across imaging modalities.

METHODS

Retrospective multicenter international study including patients with anterior circulation LVO-related acute stroke with witnessed stroke onset and baseline perfusion imaging (MRI or CT) performed within 24 hours from symptom onset. To avoid selection bias, patients were selected from (1) the prospective registries of 4 comprehensive stroke centers with systematic use of perfusion imaging and including both thrombectomy-treated and untreated patients and (2) 1 prospective thrombectomy study where perfusion imaging was acquired per protocol, but treatment decisions were made blinded to the results. EIGR was defined as infarct volume on baseline imaging divided by onset-to-imaging time and fast progressors as EIGR ≥10 mL/h. The HIR, defined as the proportion of time-to-maximum (Tmax) >6 second with Tmax >10 second volume, was measured on perfusion imaging using RAPID software. The factors independently associated with fast progression were studied using multivariable logistic regression models, with separate analyses for CT- and MRI-assessed patients.

RESULTS

Overall, 1,127 patients were included (CT, n = 471; MRI, n = 656). Median age was 74 years (interquartile range [IQR] 62-83), 52% were male, median NIH Stroke Scale was 16 (IQR 9-21), median HIR was 0.42 (IQR 0.26-0.58), and 415 (37%) were fast progressors. The HIR was the primary factor associated with fast progression, with very similar results across imaging modalities: The proportion of fast progressors was 4% in the first HIR quartile (i.e., excellent collaterals), ∼15% in the second, ∼50% in the third, and ∼77% in the fourth (p < 0.001 for each imaging modality). Fast progression was independently associated with poor 3-month functional outcome in both the CT and MRI cohorts (p < 0.001 and p = 0.030, respectively).

DISCUSSION

The HIR is the primary factor associated with fast infarct progression, regardless of imaging modality. These results have implication for neuroprotection trial design, as well as informing triage decisions at primary stroke centers.

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

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

Angiographic collateral venous phase: a novel landmark for leptomeningeal collaterals evaluation in acute ischemic stroke

BACKGROUND

Although recanalization rates constantly increase (>80%), a favorable clinical outcome is achieved in only 45-55% of patients undergoing mechanical thrombectomy (MT) for anterior circulation stroke. Collateral circulation seems to play a major role in determining this discrepancy. The aim of the study was to investigate a novel angiographic landmark assessing the collateral venous phase (CVP) compared with the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) score, based on the arterial collateral assessment.

METHODS

Two hundred patients with anterior circulation stroke treated by MT between 2016 and 2021 were included. The ASITN/SIR score and the presence of CVP were blindly evaluated by expert neuroradiologists. Three subanalyses were performed comparing patients with good versus poor collaterals, CVP presence versus absence, and a composite analysis including both ASITN/SIR and CVP grading results.

RESULTS

Good collateral circulation (ASITN >2) was observed in 113 patients (56.5%) whereas CVP was present in 90 patients (45%) and mostly in patients with good collaterals. Favorable clinical and neuroradiological outcomes were more likely observed in patients with both good collaterals and the presence of CVP than in those with good collaterals and absence of CVP (modified Rankin Scale score 0-2: 77.3% vs 7.9%, p<0.0001; mortality: 9.3% vs 26.3%, p=0.02; 24-hour Alberta Stroke Program Early CT Score: 8 vs 6, p<0.0001), while ASITN/SIR score alone was not significantly associated with clinical outcomes.

CONCLUSIONS

The presence of CVP improves the angiographic assessment of collateral circulation. CVP could be proposed as a new imaging landmark to better understand the functionality of collaterals.

Endovascular recanalization in patients with severely disabling non-acute ischemic stroke

BACKGROUND

It is unclear whether patients with severely disabling ischemic stroke (SDIS-that is, modified Rankin scale (mRS) scores of 3-5) benefit from non-acute endovascular recanalization (ER).

OBJECTIVE

To determine the effect of non-acute ER or medical treatment in severely disabled patients with non-acute ischemic stroke (mRS scores of 3-5).

METHODS

Between January 2018 and August 2021, non-acute patients with SDIS and large vessel occlusion were collected from two regional stroke centers. Patients who met the inclusion and exclusion criteria were assigned to two groups based on whether they underwent ER (ER group) or not (medical group). The primary functional outcome was the mRS score at 90 days. The primary safety outcomes were the recurrence of stroke and mortality.

RESULTS

Of the 325 patients with hypoperfusion cerebral infarction caused by large vessel occlusion, 63 met the inclusion criteria (32 patients in the ER group, 31 patients in the medical group). A favorable outcome (mRS score ≤2) occurred more often in the ER group than in the medical group (59.4% vs 22.6%, respectively; OR=0.12, 95% CI 0.02 to 0.58; P<0.01). There were no significant differences in new-onset ischemic stroke (6.3% vs 3.2%, respectively; P=1.000), symptomatic intracerebral hemorrhage (12.5% vs 0%, respectively; P=0.113), or mortality within 90 days (6.3% vs 6.5%, respectively; P=1.000) between the two groups. Preoperative mRS scores (OR=7.34, 95% CI 1.56 to 34.5; P=0.02) and ER (OR=0.12, 95% CI 0.02 to 0.58; P<0.01) were significantly associated with outcome.

CONCLUSION

Our data suggest that patients with SDIS (mRS score 3-5) with smaller infarct cores and better collateral circulation can benefit from non-acute ER, with no additional perioperative complications or mortality.

Imaging predictors of clinical outcomes after endovascular treatment in MRI-selected patients with acute basilar artery occlusion

PURPOSE

We aimed to investigate the impact of baseline infarct area and collateral status (CS), which are imaging predictors of clinical outcome following stroke, after endovascular treatment (EVT) in MRI-selected patients with acute basilar artery occlusion (BAO).

METHODS

Patients with acute BAO who underwent EVT within 24 h after stroke from December 2013 to February 2021 were included in this retrospective, multicenter, observational study. The baseline infarct area was evaluated by the posterior circulation of Acute Stroke Prognosis Early Computed Tomography Score (pc-ASPECTS) using diffuse-weighted imaging (DWI), and CS was assessed by measuring the computed tomography angiography of the basilar artery (BATMAN) score and the posterior circulation collateral score (PC-CS) using magnetic resonance angiography (MRA). A Good outcome was defined as a modified Rankin scale score ≤ 3 at 3 months. For each imaging predictor, a multivariate logistic regression analysis was performed to evaluate its impact on good outcomes.

RESULTS

A total of 86 patients were analyzed, and 37 (43.0%) had a good outcome. The latter showed significantly higher pc-ASPECTS than those without good outcomes. In multivariate analyses, a pc-ASPECTS ≥ 7 was significantly associated with good outcomes (OR, 2.98 [95% CI, 1.10-8.13], P = 0.032), while PC-CS ≥ 4 (OR, 2.49 [95% CI, 0.92-6.74], P = 0.073) and BATMAN score ≥ 5 (OR, 1.51 [95% CI, 0.58-3.98], P = 0.401) were not.

CONCLUSIONS

In MRI-selected patients with acute BAO, pc-ASPECTS on DWI was an independent predictor of clinical outcomes after EVT, while the MRA-based CS assessments were not.

Bridging Thrombolysis Before Endovascular Therapy in Stroke Patients With Faster Core Growth

BACKGROUND AND OBJECTIVES

It is still uncertain that going direct to endovascular thrombectomy (EVT) leads to equivalent outcomes as bridging IV thrombolysis (IVT) in acute ischemic patients. This study aimed to explore whether the rate of ischemic core growth influenced the patient outcomes after bridging IVT vs direct EVT.

METHODS

This was a retrospective cohort study based on the International Stroke Perfusion Imaging Registry (INSPIRE). It selected acute ischemic stroke patients receiving perfusion CT within 4.5 hours of stroke onset. Patients who went direct to EVT were compared with those who received bridging treatment of IVT before EVT. Ischemic core growth rate was estimated by the acute ischemic core volume on perfusion CT divided by the time from stroke onset to perfusion CT, based on the assumption of a linear growth pattern of ischemic core. Core growth rate was stratified into fast (>15 mL/h) and slow (≤15 mL/h), based on its interaction with bridging IVT in predicting the primary outcome. The primary outcome was modified Rankin scale of 0-2 at 3 months. The secondary outcomes included successful thrombectomy reperfusion defined by modified Thrombolysis in Cerebral Infarction score of 2b-3 and time from groin puncture to reperfusion.

RESULTS

Of the 1,221 EVT patients in the INSPIRE, 323 patients were selected, of which 82 patients received direct EVT and 241 patients received bridging IVT. Bridging IVT was associated with a higher rate of good clinical outcome among patients with fast core growth (39% vs 7% for direct EVT, odds ratio [OR] 8.75 [1.96-39.1], p = 0.005), but the difference was not notable for patients with slow core growth (55% vs 55% for direct EVT, OR 1.00 [0.53-1.87], p = 0.989). In patients with fast core growth, the bridging and direct EVT patients showed no difference in the reperfusion rate (80% vs 76%, p = 0.616). However, patients who received bridging IVT were more likely to achieve reperfusion earlier (the median groin to reperfusion time of 63.0 vs 94.0 minutes, p = 0.005).

DISCUSSION

Patients with fast core growth were more likely to benefit from bridging IVT. This is likely because prior IVT facilitates clot removal and thus reduces time to reperfusion.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Quantification of Penumbral Volume in Association With Time From Stroke Onset in Acute Ischemic Stroke With Large Vessel Occlusion

Importance

The benefit of reperfusion therapies for acute ischemic stroke decreases over time. This decreasing benefit is presumably due to the disappearance of salvageable ischemic brain tissue (ie, the penumbra).

Objective

To study the association between stroke onset-to-imaging time and penumbral volume in patients with acute ischemic stroke with a large vessel occlusion.

Design, Setting, and Participants

A retrospective, multicenter, cross-sectional study was conducted from January 1, 2015, to June 30, 2022. To limit selection bias, patients were selected from (1) the prospective registries of 2 comprehensive centers with systematic use of magnetic resonance imaging (MRI) with perfusion, including both thrombectomy-treated and untreated patients, and (2) 1 prospective thrombectomy study in which MRI with perfusion was acquired per protocol but treatment decisions were made with clinicians blinded to the results. Consecutive patients with acute stroke with intracranial internal carotid artery or first segment of middle cerebral artery occlusion and adequate quality MRI, including perfusion, performed within 24 hours from known symptoms onset were included in the analysis.

Exposures

Time from stroke symptom onset to baseline MRI.

Main Outcomes and Measures

Penumbral volume, measured using automated software, was defined as the volume of tissue with critical hypoperfusion (time to maximum >6 seconds) minus the volume of the ischemic core. Substantial penumbra was defined as greater than or equal to 15 mL and a mismatch ratio (time to maximum >6-second volume/core volume) greater than or equal to 1.8.

Results

Of 940 patients screened, 516 were excluded (no MRI, n = 19; no perfusion imaging, n = 59; technically inadequate perfusion imaging, n = 75; second segment of the middle cerebral artery occlusion, n = 156; unwitnessed stroke onset, n = 207). Of 424 included patients, 226 (53.3%) were men, and mean (SD) age was 68.9 (15.1) years. Median onset-to-imaging time was 3.8 (IQR, 2.4-5.5) hours. Only 16 patients were admitted beyond 10 hours from symptom onset. Median core volume was 24 (IQR, 8-76) mL and median penumbral volume was 58 (IQR, 29-91) mL. An increment in onset-to-imaging time by 1 hour resulted in a decrease of 3.1 mL of penumbral volume (β coefficient = -3.1; 95% CI, -4.6 to -1.5; P < .001) and an increase of 3.0 mL of core volume (β coefficient = 3.0; 95% CI, 1.3-4.7; P < .001) after adjustment for confounders. The presence of a substantial penumbra ranged from approximately 80% in patients imaged at 1 hour to 70% at 5 hours, 60% at 10 hours, and 40% at 15 hours.

Conclusions and Relevance

Time is associated with increasing core and decreasing penumbral volumes. Despite this, a substantial percentage of patients have notable penumbra in extended time windows; the findings of this study suggest that a large proportion of patients with large vessel occlusion may benefit from therapeutic interventions.

Reperfusion measurements, treatment time, and outcomes in patients receiving endovascular treatment within 24 hours of last known well

AIMS

The aim of this study was to explore the interaction between reperfusion and treatment time on the outcomes of patients undergoing endovascular treatment presenting within 24 h of last known well, and to compare the predictive ability of different reperfusion measurements on outcomes.

METHODS

Eligible patients from a single-center cohort were enrolled in this study. Reperfusion was assessed using reperfusion index (decreased volume of hypoperfusion lesion compared with baseline) measured by repeated perfusion imaging, and modified treatment in cerebral ischemia score measured by digital subtraction angiography, respectively. The interactions between reperfusion measurements and treatment time on outcomes were explored using multivariate-adjusted logistic and linear regression models. The predictive abilities of reperfusion measurements on outcomes were compared using area under the receiver operating characteristic curve (ROC-AUC) and values of R-square.

RESULTS

Reperfusion index and treatment time had significant interactions on 3-month modified Rankin Scale (mRS) 0-2 and infarct growth (p for interaction <0.05). Although the AUCs were statistically similar (AUCs of mRS 0-2 prediction, mTICI≥2b:0.63, mTICI≥2c:0.59, reperfusion index≥0.5:0.66, reperfusion index ≥0.9:0.73, P value of any of the two AUCs >0.05), reperfusion index≥0.9 showed the highest R-square values in outcome prediction (R-square values of 3-month mRS 0-2 and infarct growth = 0.21) among all the reperfusion measurements.

CONCLUSION

Treatment time mitigated the effect of reperfusion on outcomes of patients receiving endovascular treatment within 24 h of last known well. Reperfusion index≥0.9 might serve as a better proxy of good outcomes compared with other reperfusion measurements.

Ischemic Lesion Growth in Patients with a Persistent Target Mismatch After Large Vessel Occlusion

BACKGROUND

Failure to reperfuse a cerebral occlusion resulting in a persistent penumbral pattern has not been fully described.

METHODS

We retrospectively reviewed patients with anterior large vessel occlusion who did not receive reperfusion, and underwent repeated perfusion imaging, with baseline imaging < 6 h after onset and follow-up scans from 16-168 h. A persistent target mismatch (PTM) was defined as core volume of < 100 mL, mismatch ratio > 1.2, and mismatch volume > 10 mL on follow-up imaging. Patients were divided into PTM or non-PTM groups. Ischemic core and penumbral volumes were compared between baseline and follow-up imaging between the two groups, and collateral flow status assessed using CT perfusion collateral index.

RESULTS

A total of 25 patients (14 PTM and 11 non-PTM) were enrolled in the study. Median core volumes increased slightly in the PTM group, from 22 to 36 ml. There was a much greater increase in the non-PTM group, from 57 to 190 ml. Penumbral volumes were stable in the PTM group from a median of 79 ml at baseline to 88 ml at follow-up, whereas penumbra was reduced in the non-PTM group, from 120 to 0 ml. Collateral flow status was also better in the PTM group and the median collateral index was 33% compared with 44% in the non-PTM group (p = 0.043).

CONCLUSION

Multiple patients were identified with limited core growth and large penumbra (persistent target mismatch) > 16 h after stroke onset, likely due to more favorable collateral flow.

Collateral circulation predicts 3-month functional outcomes of subacute ischemic stroke patients: A study combining arterial spin labeling and MR angiography

OBJECTIVE

Collateral circulation could help preserve the blood supply and protect penumbra in ischemic stroke (IS), critical for late-window therapeutic decisions and clinical outcomes. In this study, we aimed to investigate the prognostic value of two collateral indexes measured by arterial spin labeling (ASL) and MR angiography (MRA) in subacute IS patients.

MATERIALS AND METHODS

Fifty-five subacute IS patients with large artery atherosclerosis were retrospectively collected. Arterial transit artifact (ATA) on ASL and good circulation (GC) on MRA were ranked as markers of leptomeningeal collaterals and fast collaterals, respectively. Volume and relative cerebral blood flow (rCBF) of infarct and hypoperfusion area were calculated. Stroke severity was determined by baseline- and discharge- National Institute of Hospital Stroke Scale (NIHSS). Functional independence (FI) was defined as 3-month modified Ranking Scale ≤2. Univariate analyses and multivariable logistic regression analyses were conducted to identify the independent predictors of FI.

RESULTS

Thirty-eight patients (69.1 %) presented ATA and 29 (52.7 %) patients presented GC. Univariate analyses showed that baseline-NIHSS, discharge-NIHSS, rCBF of infarct, presence of ATA and GC were associated with FI (P < 0.05). After multivariable adjustment, ATA (adjusted Odds Ratio [OR]: 13.785, 95 % CI: 2.608-72.870, P = 0.002) and GC (adjusted OR: 8.317, 95 % CI: 1.629-42.454, P = 0.011) remained independent predictors of FI. Besides, patients with both ATA and GC had the highest frequencies of FI while patients with neither of them showed the lowest (94.7 % vs 14.3 %, P < 0.001), indicating a positive synergistic effect between ATA and GC.

CONCLUSION

The combination of ASL and MRA simultaneously reflects leptomeningeal collaterals and fast collaterals, providing a useful method to predict functional outcomes of subacute IS patients.

Determinants of Infarct Core Growth During Inter-hospital Transfer for Thrombectomy

OBJECTIVE

Patients with acute ischemic stroke harboring a large vessel occlusion who present to primary stroke centers often require inter-hospital transfer for thrombectomy. We aimed to determine clinical and imaging factors independently associated with fast infarct growth (IG) during inter-hospital transfer.

METHODS

We retrospectively analyzed data from acute stroke patients with a large vessel occlusion transferred for thrombectomy from a primary stroke center to one of three French comprehensive stroke centers, with an MRI obtained at both the primary and comprehensive center before thrombectomy. Inter-hospital IG rate was defined as the difference in infarct volumes on diffusion-weighted imaging between the primary and comprehensive center, divided by the delay between the two MRI scans. The primary outcome was identification of fast progressors, defined as IG rate ≥5 mL/hour. The hypoperfusion intensity ratio (HIR), a surrogate marker of collateral blood flow, was automatically measured on perfusion imaging.

RESULTS

A total of 233 patients were included, of whom 27% patients were fast progressors. The percentage of fast progressors was 3% among patients with HIR < 0.40 and 71% among those with HIR ≥ 0.40. In multivariable analysis, fast progression was independently associated with HIR, intracranial carotid artery occlusion, and exclusively deep infarct location at the primary center (C-statistic = 0.95; 95% confidence interval [CI], 0.93-0.98). IG rate was independently associated with good functional outcome (adjusted OR = 0.91; 95% CI, 0.83-0.99; P = 0.037).

INTERPRETATION

Our findings show that a HIR > 0.40 is a powerful indicator of fast inter-hospital IG. These results have implication for neuroprotection trial design, as well as informing triage decisions at primary stroke centers. ANN NEUROL 2023.

Collateral Blood Flow and Ischemic Core Growth

Treatment of a large vessel occlusion in the acute ischemic stroke setting focuses on vessel recanalization, and endovascular thrombectomy results in favorable outcomes in appropriate candidates. Expeditious treatment is imperative, but patients often present to institutions that do not have neurointerventional surgeons and need to be transferred to a comprehensive stroke center. These treatment delays are common, and it is important to identify factors that mitigate the progression of the ischemic core in order to maximize the preservation of salvageable brain tissue. Collateral blood flow is the strongest factor known to influence ischemic core growth, which includes the input arterial vessels, tissue-level vessels, and venous outflow. Collateral blood flow at these different levels may be imaged by specific imaging techniques that may also predict ischemic core growth during treatment delays and help identify patients who would benefit from transfer and endovascular therapy, as well as identify those patients in whom transfer may be futile. Here we review collateral blood flow and its relationship to ischemic core growth in stroke patients.

Brush sign and collateral supply as potential markers of large infarct growth after successful thrombectomy

OBJECTIVES

To investigate the relationships between brush sign and cerebral collateral status on infarct growth after successful thrombectomy.

METHODS

HIBISCUS-STROKE cohort includes acute ischemic stroke patients treated with thrombectomy after MRI triage and undergoing a day-6 MRI including FLAIR images to quantify final infarct volume (FIV). Successful reperfusion was defined as a modified thrombolysis in cerebral infarction score  ≥ 2B. Infarct growth was calculated by subtracting FIV from baseline ischemic core after co-registration and considered large (LIG) when  > 11.6 mL. Brush sign was assessed on T2*-weighted-imaging and collaterals were assessed using the hypoperfusion intensity ratio, which is the volume of Time-To-Tmax (Tmax)  ≥ 10 s divided by the volume of Tmax  ≥  6 s. Good collaterals were defined by a hypoperfusion intensity ratio  < 0.4.

RESULTS

One hundred and twenty-nine patients were included, of whom 45 (34.9%) had a brush sign and 63 (48.8%) good collaterals. Brush sign was associated with greater infarct growth (p = 0.01) and larger FIV (p = 0.02). Good collaterals were associated with a smaller baseline ischemic core (p < 0.001), larger penumbra (p = 0.04), and smaller FIV (p < 0.001). Collateral status was not significantly associated with brush sign (p = 0.20) or with infarct growth (p = 0.67). Twenty-eight (22.5%) patients experienced LIG. Univariate regressions indicated that brush sign (odds ratio (OR) = 4.8; 95% confidence interval (CI): [1.9;13.3]; p = 0.004) and hemorrhagic transformation (OR = 1.7; 95%CI: [1.2;2.6]; p = 0.04) were predictive of LIG. In multivariate regression, only the brush sign remained predictive of LIG (OR = 5.2; 95%CI: [1.8-16.6], p = 0.006).

CONCLUSIONS

Brush sign is a predictor of LIG after successful thrombectomy and cerebral collateral status is not.

KEY POINTS

• Few predictors of ischemic growth are known in ischemic stroke patients achieving successful mechanical thrombectomy. • Our results suggest that the brush sign-a surrogate marker of severe hypoperfusion-is independently associated with large ischemic growth (> 11.6 mL) after successful thrombectomy whereas cerebral collateral status does not.

Effect of intravenous thrombolysis on core growth rate in patients with acute cerebral infarction

Objective

This study aimed to investigate the effects of recombinant tissue plasminogen activator intravenous thrombolysis (IVT) on the core growth rate of acute ischemic stroke.

Methods

Stroke patients with large vessel occlusion and non-recanalization from IVT treatment were retrospectively included in this study and divided into two groups: IVT and non-IVT. The core growth rate was estimated by the acute core volume on perfusion CT divided by the last known well time from stroke to CT perfusion. The primary endpoint was the core growth rate, the tissue outcome was 24 h-ASPECTS, and the clinical outcome was a 3-month modified Rankin score.

Results

A total of 94 patients were included with 53 in the IVT group and 41 in the non-IVT group. There was no significant difference in age, gender, hypertension, diabetes, atrial fibrillation, acute NIHSS, and last known well time from stroke to CT perfusion acquisition between the two groups. The core growth rate in the IVT group was lower than that in the non-IVT group, which was statistically significant after multivariate adjustment (coefficient: -5.20, 95% CI= [-9.85, -0.56], p = 0.028). There was a significant interaction between the IVT and the collateral index in predicting the core growth rate. The analysis was then stratified according to the collateral index, and the results suggested that IVT reduced the core growth rate more significantly after the worsening of collateral circulation (coefficient: 15.38, 95% CI= [-26.25, -4.40], p = 0.007). The 3-month modified Rankin score and 24 h-ASPECTS were not statistically significant between the two groups.

Conclusion

Intravenous thrombolysis reduces the core growth rate in patients with AIS, especially those with poor collateral status.

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

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

Association between collaterals, cerebral circulation time and outcome after thrombectomy of stroke

OBJECTIVE

Cerebral circulation time (CCT) and collateral score (CS) are associated with functional outcomes in acute ischemic stroke (AIS) patients after endovascular treatment (EVT), and may be related to each other. We aim to determine the relationship between CS and CCT on functional outcomes.

METHODS

We retrospectively enrolled consecutive patients with anterior circulation large vessel occlusion (LVO) AIS who received EVT. CS and CCT were measured based on digital subtraction angiography (DSA). We defined CS 0-2 and 3-4 as poor and good collateral status, respectively, and used change of CCT (cCCT), which was defined as the change of stroke side CCT (sCCT) versus healthy side CCT (hCCT). Mediating analysis was used to evaluate the influence of cCCT on the association between CS and functional outcomes, and ROC curves were further used to explore the predictive ability of the interaction between cCCT and CS for functional outcomes.

RESULTS

A total of 100 patients were enrolled in the final analysis. A higher cCCT (r = -0.239; p = 0.017) was associated with lower CS, and cCCT mediated the association of CS with functional outcome. Logistic regression analysis found that CS, cCCT and cCCT-CS interactions were independently associated with functional outcome, and cCCT-CS interaction has better predictive performance, with a higher area under curve value than CS or cCCT alone (0.79 vs. 0.75 or 0.75).

INTERPRETATION

To our knowledge, this study provides the first report of the association of collateral status with cCCT, and their interaction effect on functional outcome in AIS-LVO patients receiving EVT.

Association Between Cerebral Autoregulation and Long-Term Outcome in Patients With Acute Ischemic Stroke

BACKGROUND

Dynamic cerebral autoregulation (CA) is known to be impaired in patients with acute ischemic stroke (AIS), but whether or not dynamic CA can predict long-term outcomes is unclear.

MATERIALS AND METHODS

This prospective study included 103 patients with AIS between September 2017 and April 2019. We measured the middle cerebral artery blood flow velocity and blood pressure within 7 days of AIS onset using a transcranial Doppler and Finometer, respectively. We conducted transfer function analysis to calculate dynamic CA indices (phase and gain), with lower phase and higher gain parameters reflecting less efficient CA. We followed up all patients after 3 and 12 months. Patients with 12-month modified Rankin Scale scores of <2 and ≥2 were defined as having favorable and unfavorable outcomes, respectively. We then analyzed the predictors of unfavorable outcomes after 3 and 12 months using logistic regression.

RESULTS

The ipsilesional phase parameter was significantly lower in patients with unfavorable outcomes than in those with favorable outcomes. Multiple logistic regression analysis revealed that the ipsilesional phase parameter and the National Institutes of Health Stroke Scale score were nonmodifiable predictors of short-term and long-term outcomes. Moreover, in receiver operating characteristic analysis, the area under the curve of the ipsilesional phase parameter was 0.646 (95% confidence interval: 0.513-0.779, P =0.044). Notably, the optimal cut-off value was 20.33 degrees (sensitivity: 63%, specificity: 70%).

CONCLUSION

Dynamic CA is an independent predictor of outcomes at 3 and 12 months in patients with AIS.

Predictive Value of Different Computed Tomography Perfusion Software Regarding 90-Day Outcome of Acute Ischemic Stroke Patients After Endovascular Treatment: A Comparison With Magnetic Resonance Imaging

OBJECTIVE

This study compared ischemic core and penumbra volumes obtained using different computed tomography perfusion (CTP) software and evaluated the predictive value of CTP and magnetic resonance imaging (MRI) results for 90-day outcomes.

METHODS

In total, 105 acute ischemic stroke patients who underwent endovascular treatment from January 2016 to December 2020 were included. Patients were divided into good and poor outcome groups by a modified Rankin Scale score. Computed tomography perfusion core and penumbra volumes were obtained using OleaSphere and Vitrea software to assess the volumetric relationship with MRI using the Spearman correlation test, intraclass correlation coefficient (ICC), and Bland-Altman plot. Three multivariable models were developed: baseline variables with MRI infarct volume, baseline variables with OleaSphere core volume, and baseline variables with Vitrea core volume. The area under the receiver operating characteristic curve of the 3 models was compared using the DeLong test.

RESULTS

Median core volumes were 27.5, 26.9, and 31.1 mL for OleaSphere, Vitrea, and MRI, respectively. There was substantial correlation and excellent agreement between OleaSphere and MRI core volume ( ρ = 0.84, P < 0.001; ICC = 0.84) and Vitrea and MRI core volume ( ρ = 0.80, P < 0.001; ICC = 0.83). The areas under curve for MRI volume, OleaSphere, and Vitrea were 0.86, 0.84, and 0.83, respectively. There were no significant differences ( P = 0.18) between the predictive value of the 3 models.

CONCLUSIONS

Computed tomography perfusion core volumes showed substantial correlation and excellent agreement with MRI. There was no significant difference in the predictive value of the 3 models, suggesting that core volumes measured using CTP software can predict patient prognosis.

Association of time to groin puncture with patient outcome after endovascular therapy stratified by etiology

Background

Randomized clinical trials and large stroke registries have demonstrated a time-dependent benefit of endovascular treatment (EVT) in patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO). The aim of this study was to investigate whether this could be applied to different stroke subtypes in a real-world single-center cohort.

Materials and methods

Consecutive ischemic stroke patients with LVOs presenting within 24 h after symptom onset were prospectively registered and retrospectively assessed. Baseline multimodal imaging was conducted before EVT. Independent predictors of functional independence [90-day modified Rankin scale (mRS), 0–2] and any incidence of intracranial hemorrhage (ICH) were explored using a stepwise logistic regression model in the entire cohort and in stroke subtypes.

Results

From 2015 to 2020, 140 eligible patients received EVT, of whom 59 (42%) were classified as large artery atherosclerosis (LAA)-related. Time from last known normal to groin puncture was identified as an independent predictor for functional independence in patients of cardioembolic (CE) subtype [odds ratio (OR) 0.90 per 10 min; 95% CI 0.82–0.98; P = 0.013] but not in the LAA subtype and the whole cohort. Groin puncture within 6 h after the time of last known normal was associated with a lower risk of any ICH in the whole cohort (OR 0.36, 95% CI 0.17–0.75, P = 0.007). Sensitivity analysis of patients with complete imaging profiles also confirmed the above findings. Besides, compared with patients of the CE subtype, the LAA subtype had a smaller baseline ischemic core volume, a better collateral status, a slower core growth rate, and a numerically smaller final infarct volume.

Conclusion

Faster groin puncture has a more pronounced effect on the functional outcome in patients of CE subtype than those of LAA subtype. Reducing time to groin puncture is of great importance in improving the prognosis of patients after EVT, especially those of CE subtype, and reducing the incidence of any ICH in all patients.

Development and validation of comprehensive clinical outcome prediction models for acute ischaemic stroke in anterior circulation based on machine learning

The current prediction models for the clinical outcome of acute ischaemic stroke (AIS) remain insufficient for individualized patient management strategies. We aimed to investigate machine learning (ML) performance in the clinical outcome prediction of AIS in anterior circulation and evaluate the clinical outcome by combining the quantitative evaluation indicators of perfusion features and basic clinical information. Four ML classifiers, support vector machine (SVM), naive Bayes (NB), logistic regression (LR), and random forest (RF) were trained on a cohort of 389 adult patients (training cohort [70 %]; external validation cohort [30 %]) from the Acute Stroke Center Registry of Huashan Hospital. Model performance was compared by a range of learning metrics. Most imaging parameters were strongly correlated with the outcome (range, 0.57 to 0.81), and the correlation between relative cerebral blood flow (rCBF) < 30 % and clinical outcome was the strongest (ρ = 0.81). As the reference parameters increased, the performance of the four models was greatly improved [SVM (AUC: from 0.79 to 0.99, F1-score: from 0.61 to 0.90), RF (AUC: from 0.88 to 0.98, F1-score: from 0.71 to 0.96), LR (AUC: from 0.80 to 0.97, F1-score: from 0.64 to 0.95), and NB (AUC: from 0.74 to 0.97, F1-score: from 0.66 to 0.92)]. The ensemble classifier model with all parameters had the highest F1-score (0.97). All the ML models, jointly considering the basic clinical information and quantitative evaluation indicators of computed tomography perfusion (CTP), showed good performance in the prediction of clinical outcome of AIS in anterior circulation.

Advances in cerebral perfusion imaging techniques in acute ischemic stroke

The application of cerebral perfusion imaging has demonstrated significant assessment benefits and an ability to establish an appropriate triage of patients with acute ischemic stroke (AIS) and large artery occlusion (LAO) in the extended time window. Computed tomography perfusion (CTP) and magnetic resonance imaging (MRI) are routinely used to determine the ischemic core, as well as the tissue at risk, to aid in therapeutic decision-making. However, the time required to transport patients to imaging extends the door-to-reperfusion time. C-arm cone-beam CT (CBCT) is a novel tomography technology that combines 2D radiography and 3D CT imaging based on the digital subtraction angiography platform. In comparison with CT or MRI perfusion techniques, CBCT combined with catheterized angiogram or therapy can serve as a "one-stop-shop" for the diagnosis and treatment of AIS, and greatly reduce the door to reperfusion time. Here, we review the current evidence on the efficacy and theoretical basis of CBCT, as well as other perfusion techniques, with the purpose to assist clinicians to establish an effective and repaid workflow for patients with AIS and LAO in clinical practice.

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

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