Imaging-based treatment selection for intravenous and intra-arterial stroke therapies: a comprehensive review

Targeted Delivery of Macrophage Membrane Biomimetic Liposomes Through Intranasal Administration for Treatment of Ischemic Stroke

Purpose

Ginsenoside Rg3 (Rg3) and Panax notoginseng saponins (PNS) can be used for ischemic stroke treatment, however, the lack of targeting to the ischemic region limits the therapeutic effect. To address this, we leveraged the affinity of macrophage membrane proteins for inflamed brain microvascular endothelial cells to develop a macrophage membrane-cloaked liposome loaded with Rg3 and PNS (MM-Lip-Rg3/PNS), which can precisely target brain lesion region through intranasal administration.

Methods

MM-Lip-Rg3/PNS was prepared by co-extrusion method and was performed by characterization, stability, surface protein, and morphology. The cellular uptake, immune escape ability, and blood-brain barrier crossing ability of MM-Lip-Rg3/PNS were studied in vitro. The in vivo brain targeting, biodistribution and anti-ischemic efficacy of MM-Lip-Rg3/PNS were evaluated in MACO rats, and we determined the diversity of the nasal brain pathway through the olfactory nerve blockade model in rats. Finally, the pharmacokinetics and brain targeting index of MM-Lip-Rg3/PNS were investigated.

Results

Our results indicated that MM-Lip-Rg3/PNS was spherical with a shell-core structure. MM-Lip-Rg3/PNS can avoid mononuclear phagocytosis, actively bind to inflammatory endothelial cells, and have the ability to cross the blood-brain barrier. Moreover, MM-Lip-Rg3/PNS could specifically target ischemic sites, even microglia, increase the cumulative number of drugs in the brain, improve the inflammatory environment of the brain, and reduce the infarct size. By comparing olfactory nerve-blocking rats with normal rats, it was found that there are direct and indirect pathways for nasal entry into the brain. Pharmacokinetics demonstrated that MM-Lip-Rg3/PNS exhibited stronger brain targeting and prolonged drug half-life.

Conclusion

MM-Lip-Rg3/PNS might contribute to the accumulation of Rg3 and PNS in the ischemic brain area to improve treatment efficacy. This biomimetic nano-drug delivery system provides a new and promising strategy for the treatment of ischemic stroke.

Clot-based time attenuation curve as a novel imaging predictor of mechanical thrombectomy functional outcome in acute ischemia stroke

OBJECTIVES

To investigate whether a novel assessment of thrombus permeability obtained from perfusion computed tomography (CTP) can act as a more accurate predictor of clinical response to mechanical thrombectomy (MT) in acute ischemic stroke (AIS).

MATERIALS AND METHODS

We performed a study including two cohorts of AIS patients who underwent MT admitted to a single-center between April 2018 and February 2022: a retrospective development cohort (n = 71) and a prospective independent validation cohort (n = 96). Thrombus permeability was determined in terms of entire thrombus time-attenuation curve (TAC) on CTP. Association between thrombus TAC distributions and histopathological results was analyzed in the development cohort. Logistic regression was used to assess the performance of the TAC for predicting 90-day modified Rankin Scale (mRS) score, and good outcome was defined as a mRS score of  ≤ 2. Basic clinical characteristics was used to build a routine clinical model. A combined model gathered TAC and basic clinical characteristics was also developed. The performance of the three models is compared on the independent validation set.

RESULTS

Two TAC distributions were observed-unimodal (uTAC) and linear (lTAC). TAC distributions achieved strong correlations (|r|= 0.627, p < 0.001) with histopathological results, in which uTAC associated with fibrin- and platelet-rich clot while lTAC associated with red blood cell-rich clot. The uTAC was independently associated with poor outcome (odds ratio, 0.08 [95% confidence interval (CI), 0.02-0.31]; p < 0.001). TAC distributions yielded an AUC of 0.78 (95% CI, 0.70-0.87) for predicting clinical outcome. When combined clinical characteristics, the performance was significantly improved (AUC, 0.85 [95% CI, 0.76-0.93]; p < 0.001) and higher than routine clinical model (AUC, 0.69 [95% CI, 0.59-0.83]; p < 0.001).

CONCLUSIONS

Thrombus TAC on CTP were found to be a promising new imaging biomarker to predict the outcomes of MT in AIS.

CLINICAL RELEVANCE STATEMENT

This study revealed that clot-based time attenuation curve based on admission perfusion CT could reflect the permeability and composition of thrombus and, also, provide valuable information to predict the clinical outcomes of mechanical thrombectomy in patients with acute ischemia stroke.

KEY POINTS

• Two time-attenuation curves distributions achieved strong correlations (|r|= 0.627, p < 0.001) with histopathological results. • The unimodal time-attenuation curve was independently associated with poor outcome (odds ratio, 0.08 [0.02-0.31]; p < 0.001). • The time-attenuation curve distributions yielded a higher performance for detecting clinical outcome than routine clinical model (AUC, 0.78 [0.70-0.87] vs 0.69 [0.59-0.83]; p < 0.001).

MRI of cerebral oedema in ischaemic stroke and its current use in routine clinical practice

Currently, with the knowledge of the role of collateral circulation in the development of cerebral ischaemia, traditional therapeutic windows are being prolonged, with time not being the only criterion. Instead, a more personalised approach is applied to select additional patients who might benefit from active treatment. This review briefly describes the current knowledge of the pathophysiology of the development of early ischaemic changes, the capabilities of MRI to depict such changes, and the basics of the routinely used imaging techniques broadly available for the assessment of individual phases of cerebral ischaemia, and summarises the possible clinical use of routine MR imaging, including patient selection for active treatment and assessment of the outcome on the basis of imaging.

Integrative Approaches in Acute Ischemic Stroke: From Symptom Recognition to Future Innovations

Among the high prevalence of cerebrovascular diseases nowadays, acute ischemic stroke stands out, representing a significant worldwide health issue with important socio-economic implications. Prompt diagnosis and intervention are important milestones for the management of this multifaceted pathology, making understanding the various stroke-onset symptoms crucial. A key role in acute ischemic stroke management is emphasizing the essential role of a multi-disciplinary team, therefore, increasing the efficiency of recognition and treatment. Neuroimaging and neuroradiology have evolved dramatically over the years, with multiple approaches that provide a higher understanding of the morphological aspects as well as timely recognition of cerebral artery occlusions for effective therapy planning. Regarding the treatment matter, the pharmacological approach, particularly fibrinolytic therapy, has its merits and challenges. Endovascular thrombectomy, a game-changer in stroke management, has witnessed significant advances, with technologies like stent retrievers and aspiration catheters playing pivotal roles. For select patients, combining pharmacological and endovascular strategies offers evidence-backed benefits. The aim of our comprehensive study on acute ischemic stroke is to efficiently compare the current therapies, recognize novel possibilities from the literature, and describe the state of the art in the interdisciplinary approach to acute ischemic stroke. As we aspire for holistic patient management, the emphasis is not just on medical intervention but also on physical therapy, mental health, and community engagement. The future holds promising innovations, with artificial intelligence poised to reshape stroke diagnostics and treatments. Bridging the gap between groundbreaking research and clinical practice remains a challenge, urging continuous collaboration and research.

Biomarkers: Role and Scope in Neurological Disorders

Neurological disorders pose a great threat to social health and are a major cause for mortality and morbidity. Effective drug development complemented with the improved drug therapy has made considerable progress towards easing symptoms associated with neurological illnesses, yet poor diagnosis and imprecise understanding of these disorders has led to imperfect treatment options. The scenario is complicated by the inability to extrapolate results of cell culture studies and transgenic models to clinical applications which has stagnated the process of improving drug therapy. In this context, the development of biomarkers has been viewed as beneficial to easing various pathological complications. A biomarker is measured and evaluated in order to gauge the physiological process or a pathological progression of a disease and such a marker can also indicate the clinical or pharmacological response to a therapeutic intervention. The development and identification of biomarkers for neurological disorders involves several issues including the complexity of the brain, unresolved discrepant data from experimental and clinical studies, poor clinical diagnostics, lack of functional endpoints, and high cost and complexity of techniques yet research in the area of biomarkers is highly desired. The present work describes existing biomarkers for various neurological disorders, provides support for the idea that biomarker development may ease our understanding underlying pathophysiology of these disorders and help to design and explore therapeutic targets for effective intervention.

Multimodal CT imaging characteristics may predict post-reperfusion infarct volume in wake-up stroke patients

Background

Accurate prediction of subsequent infarct volume in acute ischemic stroke (AIS) patients helps determine appropriate interventions and prognosis. The objectives are to assess whether early multimodal CT imaging characteristics of wake-up stroke (WUS) patients could predict post-reperfusion infarct volume and evaluate the accuracy of baseline infarct and penumbra volumes for predicting follow-up infarct volume.

Methods

This retrospective study included WUS patients, last seen well (LSW) >6 h, with multimodal CT imaging at baseline. Baseline non-contrast CT (NCCT) and CT perfusion were analyzed using RAPID software, and CT angiography using maximum intensity projection. Post-reperfusion infarct volume was assessed at 24-h following reperfusion on magnetic resonance diffusion-weighted imaging (DWI). Patients were stratified by treatment module for analyses.

Results

Of 34 eligible patients, 9 (26.5%) received intravenous recombinant tissue plasminogen activator (r-tPA) alone and 25 (73.5%) received both endovascular thrombectomy (EVT) and r-tPA. All patients had a strong correlation between baseline NCCT alberta stroke program early CT score, clot burden score (CBS), Tan score, infarct volume, penumbra volume with 24-h post-reperfusion infarct volume (respectively, r=0.172, P=0.015; r=0.118, P=0.047; r=0.149, P=0.024; r=0.311, P=0.001 and r=0.120; P=0.045). Among reperfusion therapies, WUS patients who received EVT had a significantly lower 24-h post-reperfusion infarct volume and had a significant difference between baseline infarct volume and 24-h post-reperfusion infarct volume (respectively, 82 vs. 14, P=0.032 and 47 vs. 14, P=0.04).

Conclusions

Primarily obtained multimodal CT imaging characteristics may predict post-reperfusion infarct volume in WUS patients, and those who underwent EVT had a significantly lower post-reperfusion infarct volume.

Glutamate Scavenging as a Neuroreparative Strategy in Ischemic Stroke

Stroke is the second highest reason of death in the world and the leading cause of disability. The ischemic stroke makes up the majority of stroke cases that occur due to the blockage of blood vessels. Therapeutic applications for ischemic stroke include thrombolytic treatments that are in limited usage and only applicable to less than 10% of the total stroke patients, but there are promising new approaches. The main cause of ischemic neuronal death is glutamate excitotoxicity. There have been multiple studies focusing on neuroprotection via reduction of glutamate both in ischemic stroke and other neurodegenerative diseases that ultimately failed due to the obstacles in delivery. At that point, systemic glutamate grabbing, or scavenging is an ingenious way of decreasing glutamate levels upon ischemic stroke. The main advantage of this new therapeutic method is the scavengers working in the circulating blood so that there is no interference with the natural brain neurophysiology. In this review, we explain the molecular mechanisms of ischemic stroke, provide brief information about existing drugs and approaches, and present novel systemic glutamate scavenging methods. This review hopefully will elucidate the potential usage of the introduced therapeutic approaches in stroke patients.

Evaluation of the Effectiveness of Post-Stroke Metformin Treatment Using Permanent Middle Cerebral Artery Occlusion in Rats

Stroke is the second leading cause of death worldwide. Treatment options for ischemic stroke are limited, and the development of new therapeutic agents or combined therapies is imperative. Growing evidence suggests that metformin treatment, due to its anti-inflammatory action, exerts a neuroprotective effect against ischemia/reperfusion-induced brain damage. Experimental assessment has typically been performed in models of cerebral transient ischemia followed by long-term reperfusion. The aim of this study was to evaluate the neuroprotective effect of metformin treatment after permanent middle cerebral artery occlusion (pMCAO) without reperfusion in rats. Neurological deficits were assessed using the Longa scale, which offers a graded scale on body movement following pMCAO. Both infarct size and brain oedema area were measured by staining with 2,3,5-triphenyltetrazolium chloride. The number of neurons and total and activated microglia, as well as interleukin 10 (IL-10) production, in brain sections were evaluated by immunohistochemical staining. Our results show that metformin treatment improves the neurological state and reduces infarct size after 120 h of pMCAO. Metformin also prevents neuronal loss in the ischemic cortex but not in the striatum after 48 h of pMCAO. Moreover, post-stroke treatment with metformin significantly decreases the number of total and activated microglia at 48 h. The anti-inflammatory effect of metformin is associated with increased IL-10 production at 48 h after pMCAO. The results of the present study suggest that post-stroke treatment with metformin exerts anti-inflammatory and neuroprotective effects in a pMCAO model.

The Protective and Reparative Role of Colony-Stimulating Factors in the Brain with Cerebral Ischemia/Reperfusion Injury

Stroke is a debilitating disease and has the ability to culminate in devastating clinical outcomes. Ischemic stroke followed by reperfusion entrains cerebral ischemia/reperfusion (I/R) injury, which is a complex pathological process and is associated with serious clinical manifestations. Therefore, the development of a robust and effective poststroke therapy is crucial. Granulocyte colony-stimulating factor (GCSF) and erythropoietin (EPO), originally discovered as hematopoietic growth factors, are versatile and have transcended beyond their traditional role of orchestrating the proliferation, differentiation, and survival of hematopoietic progenitors to one that fosters brain protection/neuroregeneration. The clinical indication regarding GCSF and EPO as an auspicious therapeutic strategy is conferred in a plethora of illnesses, including anemia and neutropenia. EPO and GCSF alleviate cerebral I/R injury through a multitude of mechanisms, involving antiapoptotic, anti-inflammatory, antioxidant, neurogenic, and angiogenic effects. Despite bolstering evidence from preclinical studies, the multiple brain protective modalities of GCSF and EPO failed to translate in clinical trials and thereby raises several questions. The present review comprehensively compiles and discusses key findings from in vitro, in vivo, and clinical data pertaining to the administration of EPO, GCSF, and other drugs, which alter levels of colony-stimulating factor (CSF) in the brain following cerebral I/R injury, and elaborates on the contributing factors, which led to the lost in translation of CSFs from bench to bedside. Any controversial findings are discussed to enable a clear overview of the role of EPO and GCSF as robust and effective candidates for poststroke therapy.

Encouraging an excitable brain state: mechanisms of brain repair in stroke

Stroke induces a plastic state in the brain. This period of enhanced plasticity leads to the sprouting of new axons, the formation of new synapses and the remapping of sensory-motor functions, and is associated with motor recovery. This is a remarkable process in the adult brain, which is normally constrained in its levels of neuronal plasticity and connectional change. Recent evidence indicates that these changes are driven by molecular systems that underlie learning and memory, such as changes in cellular excitability during memory formation. This Review examines circuit changes after stroke, the shared mechanisms between memory formation and brain repair, the changes in neuronal excitability that underlie stroke recovery, and the molecular and pharmacological interventions that follow from these findings to promote motor recovery in animal models. From these findings, a framework emerges for understanding recovery after stroke, central to which is the concept of neuronal allocation to damaged circuits. The translation of the concepts discussed here to recovery in humans is underway in clinical trials for stroke recovery drugs.

Nanomedicine for Ischemic Stroke

Stroke is a severe brain disease leading to disability and death. Ischemic stroke dominates in stroke cases, and there are no effective therapies in clinic, partly due to the challenges in delivering therapeutics to ischemic sites in the brain. This review is focused on the current knowledge of pathogenesis in ischemic stroke, and its potential therapies and diagnosis. Furthermore, we present recent advances in developments of nanoparticle-based therapeutics for improved treatment of ischemic stroke using polymeric NPs, liposomes and cell-derived nanovesicles. We also address several critical questions in ischemic stroke, such as understanding how nanoparticles cross the blood brain barrier and developing in vivo imaging technologies to address this critical question. Finally, we discuss new opportunities in developing novel therapeutics by targeting activated brain endothelium and inflammatory neutrophils to improve the current therapies for ischemic stroke.

A Convolutional Neural Network for Anterior Intra-Arterial Thrombus Detection and Segmentation on Non-Contrast Computed Tomography of Patients with Acute Ischemic Stroke

The aim of this study was to develop a convolutional neural network (CNN) that automatically detects and segments intra-arterial thrombi on baseline non-contrast computed tomography (NCCT) scans. We retrospectively collected computed tomography (CT)-scans of patients with an anterior circulation large vessel occlusion (LVO) from the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands trial, both for training (n = 86) and validation (n = 43). For testing we included patients with (n = 58) and without (n = 45) an LVO from our comprehensive stroke center. Ground truth was established by consensus between two experts using both CT angiography and NCCT. We evaluated the CNN for correct identification of a thrombus, its location and thrombus segmentation and compared these with the results of a neurologist in training and expert neuroradiologist. Sensitivity of the CNN thrombus detection was 0.86, vs. 0.95 and 0.79 for the neuroradiologists. Specificity was 0.65 for the network vs. 0.58 and 0.82 for the neuroradiologists. The CNN correctly identified the location of the thrombus in 79% of the cases, compared to 81% and 77% for the neuroradiologists. The sensitivity and specificity for thrombus identification and the rate for correct thrombus location assessment by the CNN were similar to those of expert neuroradiologists.

Retrospective single-centre experience on the effect of the DAWN trial on the utilisation pattern, diagnostic yield and accuracy of CT perfusions performed for suspected acute stroke

INTRODUCTION

The recent DAWN trial created a paradigm shift in acute stroke treatment from 'time-based' criteria (within 6 hours) to 'tissue-based' criteria dependent on advanced neuroimaging such as CT perfusion (CTP). This has expanded the thrombectomy window from 6 to 24 hours and has major implications for healthcare providers involved in acute stroke management. Our aim is to characterise changes in the utilisation, diagnostic yield and accuracy of CTP in the diagnosis of acute stroke in the year following the DAWN trial.

METHODS

Four hundred and forty-three patients underwent CTP for investigation of suspected stroke between 1 January 2017 and 31 December 2018. Studies in 2017 were considered 'pre-DAWN' while studies in 2018 were considered 'post-DAWN trial'. Electronic medical records were reviewed to extract patient characteristics. Each patient was categorised as early presenter (within 6 hours) or late presenter (over 6 hours). Chi-squared tests were performed to assess for differences in proportions between the 2 years.

RESULTS

There was a 50% increase in CTP performed from 177 in 2017 to 266 in 2018. The proportion of all CT that were CTP increased by 40% while CTP in late presenters increased by 70% in 2018. The sensitivity, specificity and proportions of CTP with a final diagnosis of acute stroke, TIA or nonstroke did not demonstrate statistically significant differences between the 2 years.

CONCLUSIONS

The CTP utilisation, particularly in late presenters, has substantially increased since the DAWN trial. This contributes to increasing burden on healthcare services related to the diagnosis and management of stroke.

Retrospective single-centre experience on the effect of the DAWN trial on the utilisation pattern, diagnostic yield and accuracy of CT perfusions performed for suspected acute stroke

INTRODUCTION

The recent DAWN trial created a paradigm shift in acute stroke treatment from 'time-based' criteria (within 6 hours) to 'tissue-based' criteria dependent on advanced neuroimaging such as CT perfusion (CTP). This has expanded the thrombectomy window from 6 to 24 hours and has major implications for healthcare providers involved in acute stroke management. Our aim is to characterise changes in the utilisation, diagnostic yield and accuracy of CTP in the diagnosis of acute stroke in the year following the DAWN trial.

METHODS

Four hundred and forty-three patients underwent CTP for investigation of suspected stroke between 1 January 2017 and 31 December 2018. Studies in 2017 were considered 'pre-DAWN' while studies in 2018 were considered 'post-DAWN trial'. Electronic medical records were reviewed to extract patient characteristics. Each patient was categorised as early presenter (within 6 hours) or late presenter (over 6 hours). Chi-squared tests were performed to assess for differences in proportions between the 2 years.

RESULTS

There was a 50% increase in CTP performed from 177 in 2017 to 266 in 2018. The proportion of all CT that were CTP increased by 40% while CTP in late presenters increased by 70% in 2018. The sensitivity, specificity and proportions of CTP with a final diagnosis of acute stroke, TIA or nonstroke did not demonstrate statistically significant differences between the 2 years.

CONCLUSIONS

The CTP utilisation, particularly in late presenters, has substantially increased since the DAWN trial. This contributes to increasing burden on healthcare services related to the diagnosis and management of stroke.

Delineation of Ischemic Core and Penumbra Volumes from MRI using MSNet Architecture

Medical image analysis tasks like segmentation and detection of injury involving manual interventions usually suffers from high inter-observer variabilities. To carry them out efficiently, various deep neural networks have been proposed recently as they provide much higher and reliable performance than the traditional image processing and manual segmentation methods. Non-invasive and robust quantification of salvageable tissue in acute ischemic stroke i.e., the ischemic penumbra, is critical for interventional stroke therapy. This paper proposes a Multi- Sequence Network (MSNet) architecture for this task. In this architecture, the information from multiple sequences are combined for identification and segmentation of core and penumbra (salvageable tissue) regions of ischemic stroke lesions and was tested on multisequence MRI ischemic lesion dataset of ISLES⁰15. Performance of the proposed architecture, in terms of dice similarity coefficient, sensitivity and specificity are found to be 0.68, 0.805 and 0.99 respectively for the core of the lesion and 0.69, 0.949 and 0.964 respectively for the penumbra region.

Ischemic stroke segmentation in multi-sequence MRI by symmetry determined superpixel based hierarchical clustering

Automated estimation of ischemic stroke evolution across different brain anatomical regions has immense potential to revolutionize stroke treatment. Multi-sequence Magnetic Resonance Imaging (MRI) techniques provide information to characterize abnormal tissues based on their anatomy and physical properties. Asymmetry of the right and left hemispheres of the brain is an important cue for abnormality estimation but using it alone is susceptible to occasional error due to self-asymmetry of the brain. A precise estimate of the symmetry axis is therefore essential for accurate asymmetry identification, which holds the key to the proposed method. The proposed symmetry determined superpixel based hierarchical clustering (SSHC) method initially estimates the lesion from inter-hemispheric asymmetry. This asymmetry further determines the thresholding parameter for hierarchically clustering the superpixels leading to an automated and accurate lesion delineation. A multi-sequence MRI based pipeline also combines the estimations from individual sequences. SSHC is evaluated on different sequences of the Loma Linda University (LLU) dataset with 26 patients and the Ischemic Stroke Lesion Segmentation (ISLES'15) dataset with 28 patients. SSHC eliminates the need for manual determination of threshold for combining the superpixel clusters and is more reliable as it derives the information from the quick estimation of asymmetry. SSHC outperforms the state-of-the-art resulting in a high Dice similarity score of 0.704±0.27 and a recall of 0.85±0.01 which are 6% and 35% respectively higher than the challenge winning method. SSHC thus demonstrates a promising potential in the automated detection of (sub-)acute adult ischemic stroke.

Systematic review with network meta-analysis: Diagnostic values of ultrasonography, computed tomography, and magnetic resonance imaging in patients with ischemic stroke

BACKGROUND AND OBJECTIVE

Ischemic stroke is a foremost cause for disability and death worldwide. This study is conducted in order to compare the diagnostic values between transcranial Doppler ultrasound (ultrasonography), computed tomography (CT), and magnetic resonance imaging (MRI) in patients suffering from ischemic stroke by performing a network meta-analysis.

METHODS

We made use of Cochrane Library, PubMed, and Embase in order to obtain literature and papers. The combination analysis of both direct and indirect evidence in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy was conducted so as to assess the odds ratios (ORs) and surface under the cumulative ranking curve (SUCRA) values of the seven different imaging methods. These imaging techniques include ultrasonography, computed tomography (traditional CT, computed tomography angiography [CTA], computed tomography perfusion [CTP]), and MRI (traditional MRI, diffusion-weighted imaging [DWI], magnetic resonance angiography), in order to properly diagnose ischemic stroke patients.

RESULTS

Thirteen eligible diagnostic trials were enrolled into this network meta-analysis. The results of the traditional meta-analysis showed that among CT methods, CTP showed higher sensitivity, NPV, and accuracy; among MRI methods, DWI had relatively higher sensitivity, NPV, and accuracy. The results of network meta-analysis showed that DWI had relatively higher sensitivity, NPV, and accuracy when compared with traditional CT, CTA, magnetic resonance angiography and traditional MRI. CTP showed higher SUCRA among CT methods while DWI showed higher SUCRA among MRI methods. A cluster analysis revealed that DWI had the highest diagnostic value in terms of sensitivity, PPV, NPV, and accuracy amongst the aforementioned seven imaging techniques.

CONCLUSION

This network meta-analysis provides supporting evidence to the idea that DWI has a higher diagnostic value regarding ischemic stroke among MRI methods, and CTP has a poor diagnostic value among CT methods, which provide therapeutic considerations for Ischemic stroke intervention.

Thrombus Permeability on Dynamic CTA Predicts Good Outcome after Reperfusion Therapy

BACKGROUND AND PURPOSE

Thrombus permeability assessed on conventional CTA is associated with neurologic outcome in patients with acute ischemic stroke. We aimed to investigate whether dynamic CTA can improve the accuracy of thrombus permeability assessment and its predictive value for outcome.

MATERIALS AND METHODS

We reviewed consecutive patients with acute ischemic stroke who had occlusion of the M1 segment of the middle artery cerebral artery and underwent pretreatment perfusion CT. Thrombus permeability, determined by thrombus attenuation increase (TAI), was assessed on 26-phase dynamic CTA derived from perfusion CT. TAI_max was defined as the maximum TAI among phases; TAI_peak, as TAI of peak arterial phase; TAI_con, as TAI on phase 13. Good outcome was defined as a 3-month mRS score of ≤2.

RESULTS

One hundred four patients were enrolled in the final analysis. The median TAI_max, TAI_peak, and TAI_con were 30.1 HU (interquartile range, 13.0-50.2 HU), 9.5 HU (interquartile range, -1.6-28.7 HU), and 6.6 HU (interquartile range, -5.1-24.4 HU), respectively. Multivariable regression analyses showed that TAI_max (OR = 1.027; 95% CI, 1.007-1.048; P = .008), TAI_peak (OR = 1.029; 95% CI, 1.005-1.054; P = .020), and TAI_con (OR = 1.026; 95% CI, 1.002-1.051; P = .037) were independently associated with good outcome. The areas under the ROC curve of TAI_max, TAI_peak, and TAI_con in predicting good outcome were 0.734, 0.701, and 0.658, respectively.

CONCLUSIONS

Thrombus permeability assessed on dynamic CTA could be a better predictor of outcome after reperfusion therapy than that assessed on conventional single-phase CTA.

Reperfusion therapy in acute ischemic stroke: dawn of a new era?

Following the success of recent endovascular trials, endovascular therapy has emerged as an exciting addition to the arsenal of clinical management of patients with acute ischemic stroke (AIS). In this paper, we present an extensive overview of intravenous and endovascular reperfusion strategies, recent advances in AIS neurointervention, limitations of various treatment paradigms, and provide insights on imaging-guided reperfusion therapies. A roadmap for imaging guided reperfusion treatment workflow in AIS is also proposed. Both systemic thrombolysis and endovascular treatment have been incorporated into the standard of care in stroke therapy. Further research on advanced imaging-based approaches to select appropriate patients, may widen the time-window for patient selection and would contribute immensely to early thrombolytic strategies, better recanalization rates, and improved clinical outcomes.

Added value of multiphase CTA imaging for thrombus perviousness assessment

PURPOSE

Thrombus perviousness has been associated with favorable functional outcome in acute ischemic stroke (AIS) patients. Measuring thrombus perviousness on CTA may be suboptimal due to potential delay in contrast agent arrival in occluded arteries at the moment of imaging. Dynamic sequences acquired over time can potentially overcome this issue. We investigate if dynamic CTA has added value in assessing thrombus perviousness.

METHODS

Prospectively collected image data of AIS patients with proven occlusion of the anterior or posterior circulation with thin-slice multi-phase CTA (MCTA) and non-contrast CT were co-registered (n = 221). Thrombus attenuation increase (TAI; a perviousness measure) was measured for the arterial, venous, and delayed phase of the MCTA and time-invariant CTAs (TiCTA). Associations with favorable clinical outcome (90-day mRS ≤ 2) were assessed using univariate and multivariable regressions and calculating areas under receiver operating curves (AUC).

RESULTS

TAI determined from the arterial phase CTA was superior in the association with favorable outcome with OR = 1.21 per 10 HU increase (95%CI 1.04-1.41, AUC 0.62, p = 0.014) compared to any other phase (venous 1.14(95%CI 1.01-1.30, AUC 0.58, p = 0.033), delayed 1.046(95%CI 0.919-1.19, AUC 0.53, p = 0.50)), and TiCTA (1.15(95%CI 1.02-1.30, AUC 0.60, p = 0.022). In the multivariable model, only TAI on arterial phase was significantly associated with favorable outcome (aOR 1.59, 95%CI 1.04-2.43, p = 0.032).

CONCLUSION

Association between TAI with functional outcome was optimal on arterial-phase CTA such that dynamic CTA imaging has no additional benefits in current thrombus perviousness assessment, thereby suggesting that the delay of contrast arrival at the clot is a key variable for patient functional outcome.

Baseline collateral status and infarct topography in post-ischaemic perilesional hyperperfusion: An arterial spin labelling study

Focal hyperperfusion after acute ischaemic stroke could be of prognostic value depending upon its spatial localisation and temporal dynamics. Factors associated with late stage (12-24 h) perilesional hyperperfusion, identified using arterial spin labelling, are poorly defined. A prospective cohort of acute ischaemic stroke patients presenting within 4.5 h of symptom onset were assessed with multi-modal computed tomography acutely and magnetic resonance imaging at 24 ± 8 h. Multivariate logistic regression analysis and receiver operating characteristics curves were used. One hundred and nineteen hemispheric acute ischaemic stroke patients (mean age = 71 ± 12 years) with 24 h arterial spin labelling imaging were included. Forty-two (35.3%) patients showed perilesional hyperperfusion on arterial spin labelling at 24 h. Several factors were independently associated with perilesional hyperperfusion: good collaterals (71% versus 29%, P < 0.0001; OR = 5, 95% CI = [1.6, 15.7], P = 0.005), major reperfusion (81% versus 48%, P = < 0.0001; OR = 7.5, 95% CI = [1.6, 35.1], P = 0.01), penumbral salvage (76.2% versus 47%, P = 0.002; OR = 6.6, 95% CI = [1.8, 24.5], P = 0.004), infarction in striatocapsular (OR = 9.5, 95% CI = [2.6, 34], P = 0.001) and in cortical superior division middle cerebral artery (OR = 4.7, 95% CI = [1.4, 15.7], P = 0.012) territory. The area under the receiver operating characteristic curve was 0.91. Our results demonstrate good arterial collaterals, major reperfusion, penumbral salvage, and infarct topographies involving cortical superior middle cerebral artery and striatocapsular are associated with perilesional hyperperfusion.

A multicenter study of the safety and effectiveness of mechanical thrombectomy for patients with acute ischemic stroke not meeting top-tier evidence criteria

BACKGROUND

While mechanical thrombectomy (MT) has become the standard of care for patients with acute ischemic stroke (AIS) with emergent large-vessel occlusions (ELVO), recently published guidelines appropriately award top-tier evidence to the same selective criteria that were employed in completed clinical trials. We sought to evaluate the safety and effectiveness of MT in patients with AIS with ELVO who do not meet top-tier evidence criteria (TTEC).

METHODS

We conducted an observational study on consecutive patients with AIS with ELVO who underwent MT at six high-volume endovascular centers. Standard safety outcomes (3-month mortality, symptomatic intracranial hemorrhage) and effectiveness outcomes (3-month functional independence: modified Rankin Scale scores of 0-2) were compared between patients meeting and failing TTEC.

RESULTS

The sample consisted of 349 (60%) controls fulfilling TTEC and 234 (40%) non-TTEC patients. Control patients meeting TTEC for MT tended to have higher functional independence rates at 3 months (47% vs 39%; p=0.055), while the rates of symptomatic intracerebral hemorrhage (sICH) were similar (9%) in both groups (p=0.983). In multivariable logistic regression models, adherence to TTEC for MT was not independently related to any safety outcome (sICH: OR 0.71, 95% CI 0.30 to 1.68, p=0.434; 3-month mortality: OR 1.27, 95% CI 0.69 to 2.33, p=0.448) or effectiveness outcome (3-month functional independence: OR 0.81, 95% CI 0.48 to 1.37, p=0.434; 3-month functional improvement: OR 0.73, 95% CI 0.48 to 1.11, p=0.138) after adjusting for potential confounders.

CONCLUSIONS

Approximately 40% of patients with AIS with ELVO offered MT do not fulfill TTEC for MT. Patients who did not meet TTEC had high rates of good clinical outcome and low complication rates.

Expanding the concept of neuroprotection for acute ischemic stroke: The pivotal roles of reperfusion and the collateral circulation

This review surveys the efforts taken to achieve clinically efficacious protection of the ischemic brain and underscores the necessity of expanding our purview to include the essential role of cerebral perfusion and the collateral circulation. We consider the development of quantitative strategies to measure cerebral perfusion at the regional and local levels and the application of these methods to elucidate flow-related thresholds of ischemic viability and to characterize the ischemic penumbra. We stress that the modern concept of neuroprotection must consider perfusion, the necessary substrate upon which ischemic brain survival depends. We survey the major mechanistic approaches to neuroprotection and review clinical neuroprotection trials, focusing on those phase 3 multicenter clinical trials for acute ischemic stroke that have been completed or terminated. We review the evolution of thrombolytic therapies; consider the lessons learned from the initial, negative multicenter trials of endovascular therapy; and emphasize the highly successful positive trials that have finally established a clinical role for endovascular clot removal. As these studies point to the brain's collateral circulation as key to successful reperfusion, we next review the anatomy and pathophysiology of collateral perfusion as it relates to ischemic infarction, as well as the molecular and genetic influences on collateral development. We discuss the current MR and CT-based diagnostic methods for assessing the collateral circulation and the prognostic significance of collaterals in ischemic stroke, and we consider past and possible future therapeutic directions.

Automated Entire Thrombus Density Measurements for Robust and Comprehensive Thrombus Characterization in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE

In acute ischemic stroke (AIS) management, CT-based thrombus density has been associated with treatment success. However, currently used thrombus measurements are prone to inter-observer variability and oversimplify the heterogeneous thrombus composition. Our aim was first to introduce an automated method to assess the entire thrombus density and then to compare the measured entire thrombus density with respect to current standard manual measurements.

MATERIALS AND METHOD

In 135 AIS patients, the density distribution of the entire thrombus was determined. Density distributions were described using medians, interquartile ranges (IQR), kurtosis, and skewedness. Differences between the median of entire thrombus measurements and commonly applied manual measurements using 3 regions of interest were determined using linear regression.

RESULTS

Density distributions varied considerably with medians ranging from 20.0 to 62.8 HU and IQRs ranging from 9.3 to 55.8 HU. The average median of the thrombus density distributions (43.5 ± 10.2 HU) was lower than the manual assessment (49.6 ± 8.0 HU) (p<0.05). The difference between manual measurements and median density of entire thrombus decreased with increasing density (r = 0.64; p<0.05), revealing relatively higher manual measurements for low density thrombi such that manual density measurement tend overestimates the real thrombus density.

CONCLUSIONS

Automatic measurements of the full thrombus expose a wide variety of thrombi density distribution, which is not grasped with currently used manual measurement. Furthermore, discrimination of low and high density thrombi is improved with the automated method.

Role of Diffusion-weighted Imaging in Acute Stroke Management using Low-field Magnetic Resonance Imaging in Resource-limited Settings

A variety of imaging modalities exist for the diagnosis of stroke. Several studies have been carried out to ascertain their contribution to the management of acute stroke and to compare the benefits and limitations of each modality. Diffusion-weighted imaging (DWI) has been described as the optimal imaging technique for diagnosing acute ischemic stroke, yet limited evidence is available on the value of DWI in the management of ischemic stroke with low-field magnetic resonance (MR) systems. Although high-field MR imaging (MRI) is desirable for DWI, low-field scanners provide an acceptable clinical compromise which is of importance to developing countries posed with the challenge of limited availability of high-field units. The purpose of this paper was to systematically review the literature on the usefulness of DWI in acute stroke management with low-field MRI scanners and present the experience in Nigeria.

Observer variability of absolute and relative thrombus density measurements in patients with acute ischemic stroke

Introduction

Thrombus density may be a predictor for acute ischemic stroke treatment success. However, only limited data on observer variability for thrombus density measurements exist. This study assesses the variability and bias of four common thrombus density measurement methods by expert and non-expert observers.

Methods

For 132 consecutive patients with acute ischemic stroke, three experts and two trained observers determined thrombus density by placing three standardized regions of interest (ROIs) in the thrombus and corresponding contralateral arterial segment. Subsequently, absolute and relative thrombus densities were determined using either one or three ROIs. Intraclass correlation coefficient (ICC) was determined, and Bland–Altman analysis was performed to evaluate interobserver and intermethod agreement. Accuracy of the trained observer was evaluated with a reference expert observer using the same statistical analysis.

Results

The highest interobserver agreement was obtained for absolute thrombus measurements using three ROIs (ICCs ranging from 0.54 to 0.91). In general, interobserver agreement was lower for relative measurements, and for using one instead of three ROIs. Interobserver agreement of trained non-experts and experts was similar. Accuracy of the trained observer measurements was comparable to the expert interobserver agreement and was better for absolute measurements and with three ROIs. The agreement between the one ROI and three ROI methods was good.

Conclusion

Absolute thrombus density measurement has superior interobserver agreement compared to relative density measurement. Interobserver variation is smaller when multiple ROIs are used. Trained non-expert observers can accurately and reproducibly assess absolute thrombus densities using three ROIs.

Electronic supplementary material

The online version of this article (doi:10.1007/s00234-015-1607-4) contains supplementary material, which is available to authorized users.

Thrombolysis for mild stroke

The term “mild stroke”, or “minor stroke” refers to the acute ischemic stroke patients with mild and nondisabling symptoms. Currently there is still no unanimous consensus on the exact definition of mild stroke. Patients with mild stroke are assumed to have a good prognosis in natural course, so they are routinely not given thrombolysis despite early emergency department arrival. Recent studies have revealed that, however, approximately one third of so-called mild stroke patients who are not treated with thrombolysis have significant disability whereas those treated are more likely to achieve a good recovery. Thus excluding all mild strokes from thrombolysis is probably not justified. Those mild stroke patients who are likely to experience early deterioration or end with disability are mostly characterized by imaging findings. Therefore, selected patients with these characteristics based on neuroimaging to be given thrombolysis might be more justified. Meanwhile, new definition should be developed to exclude those who are at a higher risk of poor outcome. Applying information from imaging may make it come true. Using neuroimaging information to define mild stroke and select patients with mild symptoms to thrombolysis may be a future direction.

Endovascular therapy for ischemic stroke

The utility of intravenous tissue plasminogen activator (IV t-PA) in improving the clinical outcomes after acute ischemic stroke has been well demonstrated in past clinical trials. Though multiple initial small series of endovascular stroke therapy had shown good outcomes as compared to IV t-PA, a similar beneficial effect had not been translated in multiple randomized clinical trials of endovascular stroke therapy. Over the same time, there have been parallel advances in imaging technology and better understanding and utility of the imaging in therapy of acute stroke. In this review, we will discuss the evolution of endovascular stroke therapy followed by a discussion of the key factors that have to be considered during endovascular stroke therapy and directions for future endovascular stroke trials.

Multimodal CT versus MRI in Selecting Acute Stroke Patients for Endovascular Treatment

Arterial revascularization is the most effective therapy for acute stroke patients. Systemic thrombolysis with recombinant tissue plasminogen activator based on baseline non-contrast CT (NCCT) imaging criteria is the only treatment approved to date, which is limited by severe timing and medical restrictions, and a narrow efficacy. The simple imaging methodology required contrast with the current wide range of imaging modalities available, which permits the physician to rapidly obtain an estimation of the most relevant pathophysiological factors involved in an acute stroke, overcoming the limited capability of NCCT. Multimodal CT and MRI combine techniques that aim to depict the neurovasculature and the status of the brain parenchyma, including the presence of hemorrhage and infarction, as well as the viability of the cerebral ischemic areas involved. These additional imaging procedures have been explored in clinical studies and trials to guide intravenous thrombolysis in acute stroke patients beyond the currently established time windows, with inconclusive results. However, emergent endovascular materials and techniques are evolving, showing promising results with increasing rates of arterial recanalization with an acceptable safety profile, therefore becoming a potential alternative and complimentary treatment, although the current lack of a high level of evidence is limiting their use in routine clinical practice. Nevertheless, these advanced neuroimaging methods can be used to improve the selection of candidates for these novel invasive therapies and, moreover, to help the interventionist to design a faster and safer procedure. In this article, we review the basic aspects of both CT and MRI modalities and the state of the evidence of these imaging tools to guide endovascular therapy, as well as the advantages and disadvantages of each method.

Development and validation of intracranial thrombus segmentation on CT angiography in patients with acute ischemic stroke

Background and Purpose

Thrombus characterization is increasingly considered important in predicting treatment success for patients with acute ischemic stroke. The lack of intensity contrast between thrombus and surrounding tissue in CT images makes manual delineation a difficult and time consuming task. Our aim was to develop an automated method for thrombus measurement on CT angiography and validate it against manual delineation.

Materials and Methods

Automated thrombus segmentation was achieved using image intensity and a vascular shape prior derived from the segmentation of the contralateral artery. In 53 patients with acute ischemic stroke due to proximal intracranial arterial occlusion, automated length and volume measurements were performed. Accuracy was assessed by comparison with inter-observer variation of manual delineations using intraclass correlation coefficients and Bland–Altman analyses.

Results

The automated method successfully segmented the thrombus for all 53 patients. The intraclass correlation of automated and manual length and volume measurements were 0.89 and 0.84. Bland-Altman analyses yielded a bias (limits of agreement) of −0.4 (−8.8, 7.7) mm and 8 (−126, 141) mm³ for length and volume, respectively. This was comparable to the best interobserver agreement, with an intraclass correlation coefficients of 0.90 and 0.85 and a bias (limits of agreement) of −0.1 (−11.2, 10.9) mm and −17 (−216, 185) mm³.

Conclusions

The method facilitates automated thrombus segmentation for accurate length and volume measurements, is relatively fast and requires minimal user input, while being insensitive to high hematocrit levels and vascular calcifications. Furthermore, it has the potential to assess thrombus characteristics of low-density thrombi.

Delayed intravenous thrombolysis based on MRI mismatch in posterior circulation stroke

The current time-based approach for patient selection for intravenous (IV) thrombolysis in an acute stroke setting neglects the individual variation of cerebral blood flow impairment. This approach restricts the eligible patient population. In the last decade, advanced imaging and especially MRI diffusion- and perfusion-weighted imaging (DWI-PWI) techniques have been used to select patients for IV thrombolysis outside the current 4.5 h time window. Most of these studies focus on the anterior (carotid artery) cerebral circulation only. We report the case of an acute ischemic stroke due to a dissection of the right vertebral artery and occlusion of the posterior inferior cerebellar artery with good clinical outcome. The patient received IV thrombolysis far beyond the current established time window. This decision was based upon a marked MRI DWI-PWI mismatch zone in the posterior circulation territory.

Quality of extracranial carotid evaluation with 256-section CT

BACKGROUND AND PURPOSE

To date, no systematic evaluation of image quality has been performed on the 256-section multidetector CT scanner for extracranial carotid evaluations. We evaluated image quality, patient dose, and examination time and compared these parameters with a 64-section multidetector CT.

MATERIALS AND METHODS

We reviewed extracranial CTA scans obtained on a 256-detector CT scanner in 50 consecutive patients. Image quality was analyzed for artifacts and vessel contrast opacification from the aortic arch to the skull base, dose to patient, and scan time. Results were compared with a control group of 50 patients imaged on a 64-section CT scanner. A Fisher exact test was used to analyze both groups with respect to vessel contrast opacification and presence of artifacts, and a Student t test was used to assess differences in patient dose between the 2 groups.

RESULTS

Quantitative and qualitative evaluations revealed >95% acceptable vessel opacification at all levels measured on the 256-section scanner. Scan time was improved (4 seconds on 256-channel). There were fewer artifacts related to metallic streak on the 256-channel CTA study, and DLP was lower on the 256-channel CTA (113.9 versus 159.8 mGy).

CONCLUSIONS

The 256-channel CTA imaging protocol for carotid arteries yielded similar vessel contrast opacification compared with the 64-channel CTA but with fewer metallic artifacts, a modest decrease in scan time, similar image quality, and a statistically significant reduction in radiation dose of 10%.

MR susceptibility imaging

This work reviews recent developments in the use of magnetic susceptibility contrast for human MRI, with a focus on the study of brain anatomy. The increase in susceptibility contrast with modern high field scanners has led to novel applications and insights into the sources and mechanism contributing to this contrast in brain tissues. Dedicated experiments have demonstrated that in most of healthy brain, iron and myelin dominate tissue susceptibility variations, although their relative contribution varies substantially. Local variations in these compounds can affect both amplitude and frequency of the MRI signal. In white matter, the myelin sheath introduces an anisotropic susceptibility that has distinct effects on the water compartments inside the axons, between the myelin sheath, and the axonal space, and renders their signals dependent on the angle between the axon and the magnetic field. This offers opportunities to derive tissue properties specific to these cellular compartments.

Pre- and Post-Angioplasty Perfusion CT with Acetazolamide Challenge in Patients with Unilateral Cerebrovascular Stenotic Disease

Objective

Perfusion computed tomography (PCT) has the ability to measure quantitative value and produce maps of mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume (CBV). We assessed cerebral hemodynamics by using these parameters and acetazolamide (ACZ) challenge for pre- and post-procedural evaluation in patients with unilateral cerebrovascular stenotic disease.

Methods

Thirty patients underwent pre-procedural PCT with ACZ challenge, and 24 patients (80%) was conducted follow up PCT after angioplasty with same protocol. The mean MTT, CBF, and CBV were measured and compared in both middle cerebral arterial (MCA) territories before and after ACZ challenge. Hemispheric ratio and percent change after ACZ challenge were calculated before and after angioplasty.

Results

The mean stenosis rate was 76.6%. Significant increases in MTT (32.6%, p=0.000) and significant decreases in CBF (-14.2%, p=0.000) were found in stenotic side MCA territories. After ACZ challenge, there were significant changes in MTT (37.4%, p=0.000), CBF (-13.1%, p=0.000), and CBV (-10.5%, p=0.001) in pre-procedural perfusion study. However, no significant increases were found in MTT, or decreases in CBF and CBV in post-procedural study. There were no significant changes after ACZ challenge also. In addition, the degrees of these changes (before and after ACZ challenge) were highly correlated with the stenotic degrees in pre-procedural perfusion study.

Conclusion

PCT with ACZ challenge appears to be a useful tool to assess the cerebral perfusion status especially in patients with unilateral symptomatic stenotic disease.

MRI profile and response to endovascular reperfusion after stroke (DEFUSE 2): a prospective cohort study

BACKGROUND

Whether endovascular stroke treatment improves clinical outcomes is unclear because of the paucity of data from randomised placebo-controlled trials. We aimed to establish whether MRI can be used to identify patients who are most likely to benefit from endovascular reperfusion.

METHODS

In this prospective cohort study we consecutively enrolled patients scheduled to have endovascular treatment within 12 h of onset of stroke at eight centres in the USA and one in Austria. Aided by an automated image analysis computer program, investigators interpreted a baseline MRI scan taken before treatment to establish whether the patient had an MRI profile (target mismatch) that suggested salvageable tissue was present. Reperfusion was assessed on an early follow-up MRI scan (within 12 h of the revascularisation procedure) and defined as a more than 50% reduction in the volume of the lesion from baseline on perfusion-weighted MRI. The primary outcome was favourable clinical response, defined as an improvement of 8 or more on the National Institutes of Health Stroke Scale between baseline and day 30 or a score of 0-1 at day 30. The secondary clinical endpoint was good functional outcome, defined as a modified Rankin scale score of 2 or less at day 90. Analyses were adjusted for imbalances in baseline predictors of outcome. Investigators assessing outcomes were masked to baseline data.

FINDINGS

138 patients were enrolled. 110 patients had catheter angiography and of these 104 had an MRI profile and 99 could be assessed for reperfusion. 46 of 78 (59%) patients with target mismatch and 12 of 21 (57%) patients without target mismatch had reperfusion after endovascular treatment. The adjusted odds ratio (OR) for favourable clinical response associated with reperfusion was 8·8 (95% CI 2·7-29·0) in the target mismatch group and 0·2 (0·0-1·6) in the no target mismatch group (p=0·003 for difference between ORs). Reperfusion was associated with increased good functional outcome at 90 days (OR 4·0, 95% CI 1·3-12·2) in the target mismatch group, but not in the no target mismatch group (1·9, 0·2-18·7).

INTERPRETATION

Target mismatch patients who had early reperfusion after endovascular stroke treatment had more favourable clinical outcomes. No association between reperfusion and favourable outcomes was present in patients without target mismatch. Our data suggest that a randomised controlled trial of endovascular treatment for patients with the target mismatch profile is warranted.

FUNDING

National Institute for Neurological Disorders and Stroke.

Endovascular treatment of acute ischemic stroke: current indications

Endovascular stroke therapy is an effective means of achieving reperfusion in stroke patients with proximal cerebral artery occlusions. However, current guideline recommendations express uncertainty regarding the clinical efficacy of catheter-based treatments, given the lack of supportive trial data. A critical problem is that it remains unclear which patients will benefit from endovascular therapy. As such, patient selection is likely highly variable in clinical practice. This article will review the existing data to discuss the clinical and imaging factors that are relevant to patient outcomes, and which may be used to guide endovascular treatment decisions. Anterior circulation strokes represent the primary focus of this review.