Thrombus Composition, Imaging, and Outcome Prediction in Acute Ischemic Stroke

Dynamic change of neutrophil-to-lymphocyte ratio and its predictive value of prognosis in acute ischemic stroke

OBJECTIVE

The present research aimed to explore the dynamic change of the neutrophil-to-lymphocyte ratio (NLR) and its relationship with functional outcome following an acute ischemic stroke (AIS), whether receiving intravenous thrombolysis (IVT) or not.

METHODS

We retrospectively analyzed data that were prospectively acquired from patients with AIS treated with IVT or not. For patients receiving IVT, the NLR was based on a blood test performed prior to IVT (d0) and at different time points after disease onset (d1, d3, d7). In addition, in the non-IVT group, the NLR was obtained at different time points after disease onset (d1, d3, d7). Follow-ups were performed 3 months after onset via telephone. In addition, a good outcome was defined as a modified Rankin scale (mRS) ≤1; a poor outcome means 2 ≤ mRS ≤ 6.

RESULTS

A total of 204 AIS patients were included in this study. The NLR presented a dynamic change as it increased to its peak at day 1 and gradually declined to its baseline at day 7, no matter whether patients were receiving IVT or not. Patients with poor outcomes have a higher NLR at various time points. The results of multivariate logistic regression analysis demonstrated that the National Institutes of Health Stroke Scale (NIHSS), NLR d1, NLR d3, and NLR d7 were independently associated with functional outcomes. The area under the receiver operating characteristic curve of NLR in predicting outcomes was as follows: NLR d3 demonstrated robust predictive power within the IVT therapy cohort, whereas NLR d7 was predictive in the non-IVT cohort. However, the most potent predictor emerged as the combination of NIHSS and NLR.

CONCLUSION

NLR has the potential to predicate diagnosis for AIS, especially when combined with the NIHSS score.

Thrombus histology does not predict stroke etiological subtype but influences recanalization

BACKGROUND

There is conflicting data on whether clot retrieved from mechanical thrombectomy can predict stroke etiology or the success of recanalization. We aimed to analyse the relation between thrombus histology and stroke aetiology as well as recanalization.

METHODOLOGY

Histopathological analysis of clots retrieved from patients with acute ischemic stroke and large vessel occlusion was done. Quantification of the amount of fibrin, red blood cells(RBC), platelets and white blood cells (WBC) in the clots were done. The clinical, imaging data and recanalization parameters were collected. The correlation between clot composition and stroke etiology as well as recanalization were analysed.

RESULTS

Of the 77 patients, the mean age was 58. 67 ± 12.96 years. The stroke etiology were cardioembolism 44(57.1 %), large artery atherosclerosis 13(16.8 %), other determined aetiology 4(5.1 %) and undetermined in 16(20.7 %) patients. There was no significant correlation between the proportions of RBC-rich, platelet-rich and fibrin-rich thrombi and the stroke etiology. The susceptibility vessel sign was associated with RBC-rich clot(92.3 % vs 7.7 %, p = .03). All RBC-rich clots(100 %) had good recanalization(p = .05). Platelet-rich clots needed less number of passes(64.7 % vs 35.3 %, p = .006) and reduced groin puncture to recanalization time(87.9 % vs 12.1 %, p = .033). WBC-rich clots required lesser number of passes(57.5 % vs 42.5 %, P = .044). In multivariate analysis, WBC-rich clots (OR 0.230, CI 0.07-0.78, p = .018) showed an independent association with reduced recanalization attempts, while platelet-rich clots showed reduced recanalization time(OR 0.09, CI 0.01-0.63, p = .016).

CONCLUSION

There was no correlation between thrombus histology and the etiological stroke subtype. However, clot composition predicted the degree of recanalization and number of passes.

Thrombo-inflammatory prognostic score can predict the outcome of stroke: a retrospective cohort study

Introduction

Inflammatory and thrombotic biomarkers are simple prognostic indicators of adverse clinical outcomes in patients with ischemic stroke (IS). However, isolated assessment of inflammatory or thrombus biomarkers in patients with IS is limited in clinical practice.

Methods

This study aimed to evaluate the predictive value of a novel, simplified thrombo-inflammatory prognostic score (TIPS) that combines both inflammatory and thrombus biomarkers in the early phase of IS and to identify high-risk patients at the time of admission. The study population comprised 915 patients with a primary diagnosis of IS in the emergency departments of five grade A tertiary hospitals in China.

Results

Patients were divided into two groups based on the modified Rankin Scale (mRS): <3 and ≥3. TIPS with a value of "2" indicates biomarkers for high inflammation and thrombosis, "1" represents a biomarker, and "0" signals the absence of a biomarker. Multivariate logistic regression analysis was employed to identify the association between TIPS and clinical outcomes. TIPS was an independent predictor of unfavorable functional outcomes and mortality. It had a superior predictive value for clinical outcomes compared to the National Institutes of Health Stroke Scale (NIHSS) (effect ratio, 37.5%), D-dimer (effect ratio, 12.5%), and neutrophil-to-lymphocyte ratio (effect ratio, 25%).

Conclusion

The survival probability of TIPS with a score of 0 is twice as high as that of TIPS with a score of 2. The survival rate for TIPS with a score of 1 is one time higher than that for TIPS with a score of 2. The predictive value of TIPS for unfavorable functional outcomes is represented by an AUC of 0.653. TIPS is associated with an increased risk of death and unfavorable functional outcomes in patients with IS and may be a useful tool for identifying high-risk patients at the time of admission.

Association of Time to Thrombolysis With Early Reperfusion After Alteplase and Tenecteplase in Patients With Large Vessel Occlusion

BACKGROUND AND OBJECTIVES

Early treatment with intravenous alteplase increases the probability of lytic-induced reperfusion in large vessel occlusion (LVO) patients. The relationship of tenecteplase-induced reperfusion and the timing of thrombolytic administration has not been explored. In this study, we performed a comparative analysis of tenecteplase and alteplase reperfusion rates and assessed their relationship to the time of thrombolytic administration.

METHODS

Patients who were initially treated with a thrombolytic within 4.5 hours of symptom onset were pooled from the Royal Melbourne Stroke Registry, EXTEND-IA, EXTEND-IA TNK, and EXTEND-IA TNK part 2 trials. The primary outcome, thrombolytic-induced reperfusion, was defined as the absence of retrievable thrombus or >50% reperfusion at initial angiographic assessment (or repeat CT perfusion/angiography). We compared the treatment effect of tenecteplase and alteplase through fixed-effects Poisson regression modelling.

RESULTS

Among 846 patients included in the primary analysis, early reperfusion was observed in 173 (20%) patients (tenecteplase: 98/470 [21%], onset-to-thrombolytic time: 132 minutes [interquartile range (IQR): 99-170], and thrombolytic-to-assessment time: 61 minutes [IQR: 39-96]; alteplase: 75/376 [19%], onset-to-thrombolytic time: 143 minutes [IQR: 105-180], thrombolytic-to-assessment time: 92 minutes [IQR: 63-144]). Earlier onset-to-thrombolytic administration times were associated with an increased probability of thrombolytic-induced reperfusion in patients treated with either tenecteplase (adjusted risk ratio [aRR] 1.05 per 15 minutes [95% confidence interval (CI) 1.00-1.12] or alteplase (aRR 1.06 per 15 minutes [95% CI 1.00-1.13]). Tenecteplase remained associated with higher rates of reperfusion vs alteplase after adjustment for onset-to-thrombolytic time, occlusion site, thrombolytic-to-assessment time, and study as a fixed effect, (adjusted incidence rate ratio: 1.41 [95% CI 1.02-1.93]). No significant treatment-by-time interaction was observed (p = 0.87).

DISCUSSION

In patients with LVO presenting within 4.5 hours of symptom onset, earlier thrombolytic administration increased successful reperfusion rates. Compared with alteplase, tenecteplase was associated with a higher probability of lytic-induced reperfusion, independent of onset-to-lytic administration times.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifiers: NCT02388061, NCT03340493.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that among patients with LVO receiving a thrombolytic, reperfusion was more likely with tenecteplase than alteplase.

Dynamic Perviousness Predicts Revascularization Success in Acute Ischemic Stroke

BACKGROUND

The predictive value of thrombus perviousness in acute ischemic stroke (AIS), as measured by computed tomography (CT), has been intensively studied with conflicting results. In this study, we investigate the predictive potential of the novel concept of dynamic perviousness using three-dimensional (3D) volumetric evaluation of occlusive thrombi.

METHODS

The full thrombus volume in 65 patients with a hyperdense artery sign on non-contrast CT (NCCT), who underwent mechanical thrombectomy (MT), was segmented. Perviousness maps were computed voxel-wise for the entire thrombus volume as thrombus attenuation increase (TAI) between NCCT and CT angiography (CTA) as well as between CTA and late venous phase CT (CTV). Perviousness was analyzed for its association with NIHSS at admission, Thrombolysis In Cerebral Infarction (TICI) score, and number of MT passes.

RESULTS

The mean late-uptake TAI of thrombi with NIHSS scores greater than 21 at admission was approximately 100% higher than for lower scored NIHSS (p between 0.05 and 0.005). Concerning revascularization results, thrombi requiring less than four MT passes had ca. 80% higher group mean late-uptake TAI than clots requiring four or more passes (p = 0.03), and thrombi with TICI score III had ca. 95% higher group mean late-uptake TAI than thrombi with TICI II (p = 0.03). Standard perviousness showed no significant correlation with MT results.

CONCLUSION

Standard thrombus perviousness of 3D clot volume is not associated with revascularization results in AIS. In contrast, dynamic perviousness assessed with a voxel-wise characterization of 3D thrombi volume may be a better predictor of MT outcomes than standard perviousness.

Current status and quality of radiomics studies for predicting outcome in acute ischemic stroke patients: a systematic review and meta-analysis

Background

Pre-treatment prediction of reperfusion and long-term prognosis in acute ischemic stroke (AIS) patients is crucial for effective treatment and decision-making. Recent studies have demonstrated that the inclusion of radiomics data can improve the performance of predictive models. This paper reviews published studies focused on radiomics-based prediction of reperfusion and long-term prognosis in AIS patients.

Methods

We systematically searched PubMed, Web of Science, and Cochrane databases up to September 9, 2023, for studies on radiomics-based prediction of AIS patient outcomes. The methodological quality of the included studies was evaluated using the phase classification criteria, the radiomics quality scoring (RQS) tool, and the Prediction model Risk Of Bias Assessment Tool (PROBAST). Two separate meta-analyses were performed of these studies that predict long-term prognosis and reperfusion in AIS patients.

Results

Sixteen studies with sample sizes ranging from 67 to 3,001 were identified. Ten studies were classified as phase II, and the remaining were categorized as phase 0 (n = 2), phase I (n = 1), and phase III (n = 3). The mean RQS score of all studies was 39.41%, ranging from 5.56 to 75%. Most studies (87.5%, 14/16) were at high risk of bias due to their retrospective design. The remaining two studies were categorized as low risk and unclear risk, respectively. The pooled area under the curve (AUC) was 0.88 [95% confidence interval (CI) 0.84-0.92] for predicting the long-term prognosis and 0.80 (95% CI 0.74-0.86) for predicting reperfusion in AIS.

Conclusion

Radiomics has the potential to predict immediate reperfusion and long-term outcomes in AIS patients. Further external validation and evaluation within the clinical workflow can facilitate personalized treatment for AIS patients. This systematic review provides valuable insights for optimizing radiomics prediction systems for both reperfusion and long-term outcomes in AIS patients.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023461671, identifier CRD42023461671.

Radiomics features on computed tomography reflect thrombus histological age prior to endovascular treatment of acute ischemic stroke

PURPOSE

To investigate the role of radiomics features in thrombus age identification and establish a CT-based radiomics model for predicting thrombus age of large vessel occlusion stroke patients.

METHODS

We retrospectively reviewed patients with middle cerebral artery occlusion receiving mechanical thrombectomy from July 2020 to March 2022 at our center. The retrieved clots were stained with Hematoxylin and Eosin (H&E) and determined as fresh or older thrombi based on coagulation age. Clot-derived radiomics features were selected by least absolute shrinkage and selection operator (LASSO) regression analysis, by which selected radiomics features were integrated into the Rad-score via the corresponding coefficients. The prediction performance of Rad-score in thrombus age was evaluated with the area under the curve (AUC) of receiver operating characteristic (ROC) curve analysis.

RESULTS

A total of 104 patients were included in our analysis, with 52 in training and 52 in validation cohort. Older thrombi were characterized with delayed procedure time, worse functional outcome and marginally associated with more attempts of device. We extracted 982 features from NCCT images. Following T test and LASSO analysis in training cohort, six radiomics features were selected, based on which the Rad-score was generated by the linear combination of features. The Rad-score showed satisfactory performance in distinguishing fresh with older thrombi, with the AUC of 0.873 (95 %CI: 0.777-0.956) and 0.773 (95 %CI: 0.636-0.910) in training and validation cohort, respectively.

CONCLUSION

This study established and validated a CT-based radiomics model that could accurately differentiate fresh with older thrombi for stroke patients receiving mechanical thrombectomy.

Association of atherogenic index of plasma with early neurological deterioration in patients with acute ischemic stroke

PURPOSE

To explore the correlation between Atherogenic Index of Plasma (AIP) and early neurological deterioration (END) in patients with acute ischemic stroke (AIS).

METHODS

A retrospective analysis of 334 patients diagnosed with AIS between January 2021 and May 2023 at the Affiliated Huai'an Hospital of Xuzhou Medical University. Patients were divided into END and non-END groups based on changes in National Institutes of Health Stroke Scale scores (NIHSS) within 7 days of admission, and the differences in the indicators between the two groups were examined using univariate analysis. The patients were then divided into three groups based on the tertile of the AIP (T1: AIP≤ -0.01; T2: 0 ≤AIP≤0.16; AIP≥0.17), and logistic regression analysis was used to examine the association between the AIP and END. Finally, the predictive ability of the AIP was evaluated using the receiver operating characteristic (ROC) curve.

RESULTS

A total of 334 patients were included, of which 64 (19.20%) had END. The results of the analysis showed that the AIP was significantly higher in the END group compared to the non-END group. Multivariable logistic regression analysis showed that higher AIP was associated with END in AIS patients (OR=3.259, 95%CI, 1.490-7.125, P = 0.003), especially in large-artery atherosclerosis (LAA) subtype (OR=4.240, 95%CI,1.30-13.87, P = 0.017). ROC analysis revealed that the best predictive cutoff value of AIP was 0.115, and the area under the ROC curves for AIP was 0.681(0.604-0.758).

CONCLUSION

Our study uncovered that higher AIP levels were associated with END development in AIS patients.

The Value of Dual-Energy Computed Tomography Angiography-Derived Parameters in the Evaluation of Clot Composition

OBJECTIVES

We aimed to assess the value of dual-energy computed tomography angiography (DE-CTA) derived parameters as a quantitative biomarker of thrombus composition in acute ischemic stroke (AIS).

METHODS

AIS patients who underwent DE-CTA before thrombectomy between August 2016 and September 2022 were included in this study. We assessed the relative proportion of red blood cells (RBCs) and the fibrin/platelet ratio (F/P) of the retrieved clots and categorized the clots as RBC-dominant (RBCs > F/P) or F/P-dominant (F/P > RBCs). The thrombus based parameters were measured on polyenergetic images (PEI), virtual monoenergetic (VM), virtual non-contrast (VNC), iodine concentration (IC), and effective atomic number (Zeff) images respectively, and the slope of the spectral Hounsfield unit curve (λHU) was calculated. These parameters were compared in the DE-CTA images of RBC- and F/P-dominant thrombi. The diagnostic performance of the parameters was analyzed using the ROC curve. Correlations between thrombus composition and DE-CTA-derived parameters were assessed.

RESULTS

The retrieved clots in 54 of 88 patients (61.36%) were RBC-dominant. The RBC-dominant thrombi showed significantly higher VNC values and lower IC, λHU, and Zeff values than the F/P-dominant thrombi (p < 0.05). The CT density measured on IC images showed the largest AUC value (AUC, 0.94; sensitivity, 77.78%; specificity, 100.00%). The Spearman rank-order correlation coefficient values showed that CT density measured on IC images of the thrombus showed the strongest association with the proportion of RBCs (r = -0.64, p < 0.001) and F/P (r = 0.65, p < 0.001).

CONCLUSIONS

DE-CTA-derived parameters, especially the CT density measured on IC images, could be associated with thrombus composition and allow for personalized thrombectomy strategies.

D-dimer to fibrinogen ratio predicts early neurological deterioration in ischemic stroke with atrial fibrillation

INTRODUCTION

The D-dimer to fibrinogen ratio (DFR) is a good indicator of clot-producing activity in thrombotic disease, but its clinical usefulness in stroke patients with nonvalvular atrial fibrillation (NVAF) has not been studied. We evaluated the association between the DFR and early neurological deterioration (END) in acute ischemic stroke (AIS) patients with NVAF.

METHODS

We included consecutive AIS patients with NVAF between 2013 and 2015 from the registry of a real-world prospective cohort from 11 large centers in South Korea. END was defined as an increase ≥2 in the total NIHSS score or ≥ 1 in the motor NIHSS score within the first 72 h of admission. The DFR was calculated as follows: DFR = D-dimer (mg/L)/fibrinogen (mg/dL) x 100.

RESULTS

A total of 1018 AIS patients with NVAF were evaluated. In multivariable logistic regression analysis, the highest DFR tertile was closely associated with END (adjusted odds ratio [aOR] = 2.14, 95 % confidence interval [CI]: 1.24-3.69). Hypertension (aOR = 1.71, 95 % CI: 1.09-2.70), initial NIHSS score (aOR = 1.05, 95 % CI: 1.02-1.07) and use of anticoagulants (aOR = 0.41, 95 % CI: 0.28-0.60) were also correlated with END. In addition to END, the DFR was correlated with discharge NIHSS and modified Rankin Scale (mRS) scores and the 3-month mRS score.

CONCLUSIONS

High DFR values were associated with END in AIS patients with NVAF. As the DFR is an indicator directly related to the main pathological mechanism of NVAF patients (fibrinolysis and coagulation), it may be useful in predicting their prognosis.

Safety and Efficacy of Tenecteplase Compared With Alteplase in Patients With Large Vessel Occlusion Stroke: A Prespecified Secondary Analysis of the ACT Randomized Clinical Trial

Importance

It is unknown whether intravenous thrombolysis using tenecteplase is noninferior or preferable compared with alteplase for patients with acute ischemic stroke.

Objective

To examine the safety and efficacy of tenecteplase compared to alteplase among patients with large vessel occlusion (LVO) stroke.

Design, Setting, and Participants

This was a prespecified analysis of the Intravenous Tenecteplase Compared With Alteplase for Acute Ischaemic Stroke in Canada (ACT) randomized clinical trial that enrolled patients from 22 primary and comprehensive stroke centers across Canada between December 10, 2019, and January 25, 2022. Patients 18 years and older with a disabling ischemic stroke within 4.5 hours of symptom onset were randomly assigned (1:1) to either intravenous tenecteplase or alteplase and were monitored for up to 120 days. Patients with baseline intracranial internal carotid artery (ICA), M1-middle cerebral artery (MCA), M2-MCA, and basilar occlusions were included in this analysis. A total of 1600 patients were enrolled, and 23 withdrew consent.

Exposures

Intravenous tenecteplase (0.25 mg/kg) vs intravenous alteplase (0.9 mg/kg).

Main Outcomes and Measures

The primary outcome was the proportion of modified Rankin scale (mRS) score 0-1 at 90 days. Secondary outcomes were an mRS score from 0 to 2, mortality, and symptomatic intracerebral hemorrhage. Angiographic outcomes were successful reperfusion (extended Thrombolysis in Cerebral Infarction scale score 2b-3) on first and final angiographic acquisitions. Multivariable analyses (adjusting for age, sex, National Institute of Health Stroke Scale score, onset-to-needle time, and occlusion location) were carried out.

Results

Among 1577 patients, 520 (33.0%) had LVO (median [IQR] age, 74 [64-83] years; 283 [54.4%] women): 135 (26.0%) with ICA occlusion, 237 (45.6%) with M1-MCA, 117 (22.5%) with M2-MCA, and 31 (6.0%) with basilar occlusions. The primary outcome (mRS score 0-1) was achieved in 86 participants (32.7%) in the tenecteplase group vs 76 (29.6%) in the alteplase group. Rates of mRS 0-2 (129 [49.0%] vs 131 [51.0%]), symptomatic intracerebral hemorrhage (16 [6.1%] vs 11 [4.3%]), and mortality (19.9% vs 18.1%) were similar in the tenecteplase and alteplase groups, respectively. No difference was noted in successful reperfusion rates in the first (19 [9.2%] vs 21 [10.5%]) and final angiogram (174 [84.5%] vs 177 [88.9%]) among 405 patients who underwent thrombectomy.

Conclusions and Relevance

The findings in this study indicate that intravenous tenecteplase conferred similar reperfusion, safety, and functional outcomes compared to alteplase among patients with LVO.

Identification of key biomarkers in ischemic stroke: single-cell sequencing and weighted co-expression network analysis

PURPOSE

At present, there is a lack of accurate early diagnostic markers for ischemic stroke.

METHODS

By using dimensionality reduction cluster analysis, differential expression analysis, weighted co-expression network analysis, protein-protein interaction network analysis, cell heterogeneity and key pathogenic genes were identified in ischemic stroke. Immunomicroenvironment analysis was used to explore the immune landscape and immune associations of key genes in ischemic stroke. The analysis platform we use is R software (version 4.0.5). PCR experiments were used to verify the expression of key genes.

RESULTS

Single cell sequencing data in ischemic stroke can be annotated as fibroblast cells, pre-B cell CD34, neutrophils cells, bone marrow (BM), keratinocytes, macrophage, neurons and mesenchymal stem cells (MSC). By the intersection of differential expression analysis and WGCNA analysis, 385 genes were obtained. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these genes were highly correlated with multiple functions and pathways. Protein-protein interaction network analysis revealed that MRPS11 and MRPS12 were key genes, both of which were down-regulated in ischemic stroke. The Pseudo-time series analysis found that the expression of MRPS12 decreased gradually with the differentiation of pre-B cell CD34 cells in ischemic stroke, suggesting that the downregulation of MRPS12 expression may play an important role in ischemic stroke. At last, PCR showed that MRPS11 and MRPS12 were significantly down-regulated in peripheral blood of patients with ischemic stroke.

CONCLUSIONS

Our study provides a reference for the study of pathogenesis and key targets of ischemic stroke.

Thrombus composition and thrombolysis resistance in stroke

A State of the Art lecture titled "Thrombus Composition and Thrombolysis Resistance in Stroke" was presented at the ISTH Congress in 2022. Intravenous thrombolysis (IVT) remains the only pharmacologic option to re-establish cerebral perfusion at the acute phase of ischemic stroke. IVT is based on the administration of recombinant tissue plasminogen activator with the objective of dissolving fibrin, the major fibrillar protein component of thrombi. Almost 30 years on from its introduction, although the clinical benefits of IVT have been clearly demonstrated, IVT still suffers from a relatively low efficacy, with a rate of successful early recanalization below 50% overall. Analyses of thrombectomy-recovered acute ischemic stroke (AIS) thrombi have shown that apart from occlusion site, thrombus length, and collateral status, AIS thrombus structure and composition are also important modulators of IVT efficacy. In this article, after a brief presentation of IVT principle and current knowledge on IVT resistance, we review recent findings on how compaction and structural alterations of fibrin together with nonfibrin thrombus components such as neutrophil extracellular traps and von Willebrand factor interfere with IVT in AIS. We further discuss how these new insights could soon result in the development of original adjuvant therapies for improved IVT in AIS. Finally, we summarize relevant new data presented during the 2022 ISTH Congress.

Brain-targeting drug delivery systems

Brain diseases, including neurodegenerative diseases, acute ischemic stroke and brain tumors, have become a major health problem and a huge burden on society with high morbidity and mortality. However, most of the current therapeutic drugs can only relieve the symptoms of brain diseases, and it is difficult to achieve satisfactory therapeutic effects fundamentally. Extensive studies have shown that the therapeutic effects of brain diseases are mainly affected by two factors: the conservation of the blood-brain barrier (BBB) and the complexity of the brain micro-environment. Brain-targeting drug delivery systems provide new possibilities for overcoming these barriers with versatility. In this review, it provides an overview of BBB alteration and discusses targeting delivery strategies for brain diseases therapy. Furthermore, delivery systems which are designed to modulate the brain micro-environment with synergistic effects were also highlighted. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Intravenous thrombolysis prior to mechanical thrombectomy does not affect clinical or procedural outcomes in patients with large vessel occlusion acute ischemic stroke

Mechanical thrombectomy (MT) has revolutionized the care of large vessel occlusion acute ischemic strokes (LVOAIS). However, the benefit of intravenous thrombolysis prior to MT remains unproven. Two recent trials showed equivocal results regarding the benefits of pre-MT intravenous thrombolysis in predominantly Asian populations. We evaluated clinical outcomes and procedural metrics for patients with LVOAIS who were treated with MT alone compared to those who were treated with both intravenous tPA and MT. In a retrospective study, LVOAIS patients treated with MT, with or without preceding intravenous thrombolysis, between January of 2017 and December of 2019 were identified. Patients were treated according to contemporary guidelines. Baseline demographic and clinical characteristics, procedural metrics, and clinical outcomes were collected. Among LVOAIS patients, those treated with intravenous thrombolysis and MT did not differ from those with MT alone on clinical outcomes at three months. Further, the two groups did not differ on thrombectomy procedure times, recanalization rates, and symptomatic intracranial hemorrhage rates. In our patients with LVOAIS, intravenous thrombolysis combined with MT offered no advantage compared to MT alone in clinical outcomes or recanalization rates. Our results are consistent with earlier studies in other populations. In addition, our results suggest that IV tPA does not impact the ease of clot removal by MT. Further studies will evaluate how newly available thrombolytic agents may benefit patients eligible for MT.

Fully Automated Thrombus Segmentation on CT Images of Patients with Acute Ischemic Stroke

Thrombus imaging characteristics are associated with treatment success and functional outcomes in stroke patients. However, assessing these characteristics based on manual annotations is labor intensive and subject to observer bias. Therefore, we aimed to create an automated pipeline for consistent and fast full thrombus segmentation. We used multi-center, multi-scanner datasets of anterior circulation stroke patients with baseline NCCT and CTA for training (n = 228) and testing (n = 100). We first found the occlusion location using StrokeViewer LVO and created a bounding box around it. Subsequently, we trained dual modality U-Net based convolutional neural networks (CNNs) to segment the thrombus inside this bounding box. We experimented with: (1) U-Net with two input channels for NCCT and CTA, and U-Nets with two encoders where (2) concatenate, (3) add, and (4) weighted-sum operators were used for feature fusion. Furthermore, we proposed a dynamic bounding box algorithm to adjust the bounding box. The dynamic bounding box algorithm reduces the missed cases but does not improve Dice. The two-encoder U-Net with a weighted-sum feature fusion shows the best performance (surface Dice 0.78, Dice 0.62, and 4% missed cases). Final segmentation results have high spatial accuracies and can therefore be used to determine thrombus characteristics and potentially benefit radiologists in clinical practice.

Quantitative thrombus characteristics on thin-slice computed tomography improve prediction of thrombus histopathology: results of the MR CLEAN Registry

OBJECTIVES

Thrombus computed tomography (CT) characteristics might be used to assess histopathologic thrombus composition in patients treated with endovascular thrombectomy (EVT) for acute ischemic stroke (AIS). We aimed to assess the variability in thrombus composition that could be predicted with combined thrombus CT characteristics.

METHODS

Thrombi of patients enrolled in the MR CLEAN Registry between March 2014 and June 2016 were histologically analyzed with hematoxylin-eosin staining and quantified for percentages of red blood cells (RBCs) and fibrin/platelets. We estimated the association between general qualitative characteristics (hyperdense artery sign [HAS], occlusion location, clot burden score [CBS]) and thrombus composition with linear regression, and quantified RBC variability that could be explained with individual and combined characteristics with R². For patients with available thin-slice (≤ 2.5 mm) imaging, we performed similar analyses for general and quantitative characteristics (HAS, occlusion location, CBS, [relative] thrombus density, thrombus length, perviousness, distance from ICA-terminus).

RESULTS

In 332 included patients, the presence of HAS (aβ 7.8 [95% CI 3.9-11.7]) and shift towards a more proximal occlusion location (aβ 3.9 [95% CI 0.6-7.1]) were independently associated with increased RBC and decreased fibrin/platelet content. With general characteristics, 12% of RBC variability could be explained; HAS was the strongest predictor. In 94 patients with available thin-slice imaging, 30% of RBC variability could be explained; thrombus density and thrombus length were the strongest predictors.

CONCLUSIONS

Quantitative thrombus CT characteristics on thin-slice admission CT improve prediction of thrombus composition and might be used to further guide clinical decision-making in patients treated with EVT for AIS in the future.

KEY POINTS

• With hyperdense artery sign and occlusion location, 12% of variability in thrombus RBC content can be explained. • With hyperdense artery sign, occlusion location, and quantitative thrombus characteristics on thin-slice (≤ 2.5 mm) non-contrast CT and CTA, 30% of variability in thrombus RBC content can be explained. • Absolute thrombus density and thrombus length were the strongest predictors for thrombus composition.