A New Era of Extended Time Window Acute Stroke Interventions Guided by Imaging

Advancements in ultrasound-mediated drug delivery for central nervous system disorders

INTRODUCTION

Central nervous system (CNS) disorders present major therapeutic challenges due to the presence of the blood - brain barrier (BBB) and disease heterogeneity. The BBB impedes most therapeutic agents, which restricts conventional treatments. Focused ultrasound (FUS) -assisted delivery offers a novel solution by temporarily disrupting the BBB and thereby enhancing drug delivery to the CNS.

AREAS COVERED

This review outlines the fundamental principles of FUS-assisted drug delivery technology, with an emphasis on its role in enhancing the spatial precision of therapeutic interventions and its molecular effects on the cellular composition of the BBB. Recent promising clinical studies are surveyed, and a comparative analysis of current US-assisted delivery system is provided. Additionally, the latest advancements and challenges of this technology are discussed.

EXPERT OPINION

FUS-mediated drug delivery shows promise, but the clinical translation of research findings is challenging. Key issues include safety, dosage optimization, and balancing efficacy with the risk of tissue damage. Continued research is crucial to address these challenges and bridge the gap between preclinical and clinical applications, and could transform treatments of CNS disorders.

Diffusion-Weighted Imaging Fluid-Attenuated Inversion Recovery Mismatch on Portable, Low-Field Magnetic Resonance Imaging Among Acute Stroke Patients

OBJECTIVE

For stroke patients with unknown time of onset, mismatch between diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) can guide thrombolytic intervention. However, access to MRI for hyperacute stroke is limited. Here, we sought to evaluate whether a portable, low-field (LF)-MRI scanner can identify DWI-FLAIR mismatch in acute ischemic stroke.

METHODS

Eligible patients with a diagnosis of acute ischemic stroke underwent LF-MRI acquisition on a 0.064-T scanner within 24 h of last known well. Qualitative and quantitative metrics were evaluated. Two trained assessors determined the visibility of stroke lesions on LF-FLAIR. An image coregistration pipeline was developed, and the LF-FLAIR signal intensity ratio (SIR) was derived.

RESULTS

The study included 71 patients aged 71 ± 14 years and a National Institutes of Health Stroke Scale of 6 (interquartile range 3-14). The interobserver agreement for identifying visible FLAIR hyperintensities was high (κ = 0.85, 95% CI 0.70-0.99). Visual DWI-FLAIR mismatch had a 60% sensitivity and 82% specificity for stroke patients <4.5 h, with a negative predictive value of 93%. LF-FLAIR SIR had a mean value of 1.18 ± 0.18 <4.5 h, 1.24 ± 0.39 4.5-6 h, and 1.40 ± 0.23 >6 h of stroke onset. The optimal cut-point for LF-FLAIR SIR was 1.15, with 85% sensitivity and 70% specificity. A cut-point of 6.6 h was established for a FLAIR SIR <1.15, with an 89% sensitivity and 62% specificity.

INTERPRETATION

A 0.064-T portable LF-MRI can identify DWI-FLAIR mismatch among patients with acute ischemic stroke. Future research is needed to prospectively validate thresholds and evaluate a role of LF-MRI in guiding thrombolysis among stroke patients with uncertain time of onset. ANN NEUROL 2024;96:321-331.

The Discovery of 7-Isopropoxy-2-(1-methyl-2-oxabicyclo[2.1.1]hexan-4-yl)-N-(6-methylpyrazolo[1,5-a]pyrimidin-3-yl)imidazo[1,2-a]pyrimidine-6-carboxamide (BIO-7488), a Potent, Selective, and CNS-Penetrant IRAK4 Inhibitor for the Treatment of Ischemic Stroke

Interleukin receptor-associated kinase 4 (IRAK4) is a key node of signaling within the innate immune system that regulates the production of inflammatory cytokines and chemokines. The presence of damage-associated molecular patterns (DAMPs) after tissue damage such as stroke or traumatic brain injury (TBI) initiates signaling through the IRAK4 pathway that can lead to a feed-forward inflammatory loop that can ultimately hinder patient recovery. Herein, we describe the first potent, selective, and CNS-penetrant IRAK4 inhibitors for the treatment of neuroinflammation. Lead compounds from the series were evaluated in CNS PK/PD models of inflammation, as well as a mouse model of ischemic stroke. The SAR optimization detailed within culminates in the discovery of BIO-7488, a highly selective and potent IRAK4 inhibitor that is CNS penetrant and has excellent ADME properties.

Image-to-image generative adversarial networks for synthesizing perfusion parameter maps from DSC-MR images in cerebrovascular disease

Stroke is a major cause of death or disability. As imaging-based patient stratification improves acute stroke therapy, dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) is of major interest in image brain perfusion. However, expert-level perfusion maps require a manual or semi-manual post-processing by a medical expert making the procedure time-consuming and less-standardized. Modern machine learning methods such as generative adversarial networks (GANs) have the potential to automate the perfusion map generation on an expert level without manual validation. We propose a modified pix2pix GAN with a temporal component (temp-pix2pix-GAN) that generates perfusion maps in an end-to-end fashion. We train our model on perfusion maps infused with expert knowledge to encode it into the GANs. The performance was trained and evaluated using the structural similarity index measure (SSIM) on two datasets including patients with acute stroke and the steno-occlusive disease. Our temp-pix2pix architecture showed high performance on the acute stroke dataset for all perfusion maps (mean SSIM 0.92-0.99) and good performance on data including patients with the steno-occlusive disease (mean SSIM 0.84-0.99). While clinical validation is still necessary for future studies, our results mark an important step toward automated expert-level perfusion maps and thus fast patient stratification.

Effectiveness and Predictors of Poor Prognosis Following Intravenous Thrombolysis in Patients with Wake-Up Ischemic Stroke Guided by Rapid MRI

PURPOSE

Our aim was to investigate the effectiveness and predictors of poor prognosis in WUIS patients who received alteplase thrombolysis under the guidance of diffusion-weighted imaging (DWI)-T2-weighted imaging (T2WI) mismatch.

PATIENTS AND METHODS

We recruited patients within 4.5 h of acute ischemic stroke (AIS) and WUIS patients with uncertain onset times from two stroke centers. To evaluate effectiveness, we compared National Institutes of Health Stroke Scale (NIHSS) scores between the two groups at admission and at 24 h, 3 days, and 1 week thereafter. We also compared the two groups with respect to the modified Rankin Scale (mRS) score at 90 days after thrombolysis. The WUIS patients were divided into a favorable prognosis group (mRS score: 0-1 points) and a poor prognosis group (mRS score ≥2 points). Data were compared between the two subgroups to identify factors that influence poor prognoses. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of factors related to poor prognosis.

RESULTS

A total of 114 patients with WUIS and 316 patients with AIS were enrolled in the study. There were no significant differences between the two groups in terms of NIHSS or 90-day mRS scores (p > 0.05). Baseline NIHSS score (odds ratio [OR] = 1.490, 95% confidence interval [CI] 1.248-1.779, p < 0.001) and atrial fibrillation (OR = 3.825, 95% CI 1.218-12.016, p = 0.022) were identified as independent predictors of poor prognosis following thrombolysis in WUIS patients. The combined ROC diagnosis of these two variables had an area under the curve of 0.850.

CONCLUSION

The DWI-T2WI sequence is an effective method to guide intravenous thrombolytic therapy for WUIS. Baseline NIHSS score and atrial fibrillation were identified as independent predictors of poor prognosis following thrombolysis in WUIS patients.

The Impact of the Pandemic on Acute Ischaemic Stroke Endovascular Treatment from a Multidisciplinary Perspective: A Nonsystematic Review

BACKGROUND

At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, reduced admissions for cerebrovascular events were identified, but acute ischaemic stroke (AIS) has remained one of the leading causes of death and disability for many years. The aim of this article is to review current literature data for multidisciplinary team (MDT) coordination, rational management of resources and facilities, ensuring timely medical care for large vessel occlusion (LVO) AIS patients requiring endovascular treatment during the pandemic.

METHODS

A detailed literature search was performed in Google Scholar and PubMed databases using these keywords and their combinations: acute ischaemic stroke, emergency, anaesthesia, airway management, mechanical thrombectomy, endovascular treatment, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), COVID-19. Published studies and guidelines from inception to April 2021 were screened. The following nonsystematic review is based on a comprehensive literature search of available data, wherein 59 were chosen for detailed analysis.

RESULTS

The pandemic has an impact on every aspect of AIS care, including prethrombectomy, intraprocedural and post-thrombectomy issues. Main challenges include institutional preparedness, increased number of AIS patients with multiorgan involvement, different work coordination principles and considerations about preferred anaesthetic technique. Care of these patients is led by MDT and nonoperating room anaesthesia (NORA) principles are applied.

CONCLUSIONS

Adequate management of AIS patients requiring mechanical thrombectomy during the pandemic is of paramount importance to maximise the benefit of the endovascular procedure. MDT work and familiarity with NORA principles decrease the negative impact of the disease on the clinical outcomes for AIS patients.