Stroke Imaging Research Articles

Diagnostic yield and therapeutic implications of vascular imaging in acute ischemic stroke: prospective and consecutive study of small vessel versus large vessel ischemia.

To evaluate patients acute cerebral ischemia in order to assess for factors which may help to differentiate patients with small vessel involvement from those with large vessel involvement in an effort to determine diagnostic yield of vascular imaging. We prospectively and consecutively evaluated all acute ischemic stroke patients at our medical center from May 16, 2021 to December 10, 2021. Distinction between small vessel and large vessel involvement was based upon clinical presentation, the results of brain imaging and either computed tomographic angiography, in the vast majority, or magnetic resonance angiography. Patient demographics and risk factors for stroke as well as therapeutic intervention was assessed. Of the 90 patients studied, 59 had large vessel ischemia (66%) with 26 (44%) having large vessel occlusion and one had symptomatic high-grade middle cerebral artery stenosis. Conversely, none of the 31 patients with small vessel presentation (34%) had large vessel occlusion or high-grade stenosis. In addition, 19 out of 59 (32%) large vessel patients compared to 2 of 31 (6%) of the small vessel patients had atrial fibrillation identified as a potential mechanism with a p-value of 0.01 by univariate analysis and 0.17 by multivariate analysis. The routine use of vascular imaging in acute ischemic stroke is of very low yield in small vessel presentation with the presence of potential cardiogenic emboli is also relatively low. Efforts at accelerated identification of a small vessel mechanism, to avoid unnecessary testing, should provide significant value from both a patient management and cost standpoint.

Abstract TP164: Feasibility of Randomizing to CT or MRI for Evaluation of First Imaging Modality for Stroke

Background: Ischemic stroke is a leading causes of death and disability and imaging is essential when determining treatment. Currently, both computed tomography (CT) and magnetic resonance (MR) are accepted as options for first imaging of stroke. Whether MR or CT is more advantageous for first stroke imaging has yet to be determined in a randomized study. The goal of this study was to determine feasibility of randomizing code stroke patients to MR or CT. Methods: Multisite, randomized, prospective study of code stroke patients presenting within a 12-week window to 4 certified stroke centers. Hospital-level cluster randomization assigned each site 6 CT-first weeks, and 6 MR-first weeks. Patients ≥18 years presenting with stroke symptoms < 24 hours with active code strokes at time of first imaging were included. Patients transferred from another hospital or who received prior imaging at an outside facility were excluded. Demographics, clinical stroke variables, and workflow metrics were extracted from the local stroke database or patient electronic health records. A univariate logistic regression model was used to evaluate the primary outcome: compliance (i.e. proportion of patients scanned according to assigned imaging). We hypothesized compliance would be comparable to that seen when MR-first was the preferred standard of care, ≥60%, demonstrating feasibility. Results: 406 patients (199 females; mean age 67 years, range 24 - 103) were included in the analysis (Table 1). Compliance with assignment to CT was 90%, compliance with MR was 66%. Those assigned to MR were significantly less likely to be scanned as assigned (OR: 0.21, 95% CI [0.12-0.36]). Reasons for non-compliance included both process-related (e.g. MR scanner in use) and patient-related reasons (e.g. medically unstable). Most frequently, the reason for non-compliance was not documented. Conclusion: This study is the first step in evaluating feasibility for a large-scale randomized clinical trial to determine whether MR or CT is preferable as the first stroke imaging modality. Compliance with assignment (MR or CT) our preset threshold of 60%, with significantly higher compliance when CT was assigned compared to MR. With mitigation of process-related barriers to randomization compliance, these results inform next steps in optimizing a future trial.

Abstract 29: Non-gated Dual-source Photon-counting CT Angiography Can Detect Cardioembolic Sources Of Acute Ischemic Stroke At The Primary Investigation: A Retrospective Consecutive Cohort Study

Introduction: Early identification of the etiology of ischemic stroke is crucial for secondary prevention. Recent publications on dedicated ECG-gated cardiac CT showcase the potential to detect sources of cardiac embolism. Photon-counting CT (PCCT) uses semiconductors to convert X-ray photons into electrical signals directly. This allows for improved image quality and lower radiation dose compared to conventional CT. Exploiting PCCT technology with a high-pitch dual-source image acquisition may render an exceptionally high temporal resolution. We hypothesized that non-ECG-gated high-pitch dual-source PCCT angiography from the diaphragm to the brain might provide added clinical value in detecting cardiac stroke sources during initial stroke imaging while maintaining optimal brain and neck image quality. Methods: Consecutive patients with a clinical suspicion of acute stroke imaged with a PCCT system between October 4 th , 2023 and April 13 th , 2024 at a Swedish comprehensive stroke center were included. Diaphragm to brain coverage was obtained in an acquisition time of 1.3 seconds; on average, yielding a dose-length product of 360 mGy*cm for the study participants (2.34 mSv). Image quality was graded using a 4-point Likert scale. Images were assessed for cardiac stroke sources. Where available, reference standard echocardiography results were collected. Results: Of 249 consecutive stroke investigations, 193 included cardiothoracic imaging, which constituted the study population. 126 scans (65.3%) were cases with imaging confirmed ischemic stroke. The median age was 74 (IQR, 61-81) years, 99 were male (51.3%). In total, 39.4% underwent follow-up echocardiography. Image quality of the heart was excellent in 19 scans (9.8%) good in 97 (50.3%), moderate in 72 (37.3%), and poor in 5 scans (2.6%). Fourteen (7.3%) certain or probable interatrial septal defects were found in the study population. In the imaging-confirmed ischemic stroke subgroup, six certain or probable cardiac thrombi were found (4.8%). Additionally, a possible cardiac thrombus was found in 31 instances (24.6%). Three aortic valve vegetations were found (2.4%), all confirmed by echocardiography. Conclusions: Non-ECG-gated high-pitch dual-source PCCT angiography typically provides images of high quality, at virtually no time expense while maintaining a reasonably low radiation exposure. Non-gated PCCT angiography is a promising technique to be used as a primary screening method for cardioembolic stroke.

Abstract WP201: The Performance of Portable Low-field Magnetic resonance imaging in Acute Ischemic Stroke

Abstract WP201: The Performance of Portable Low-field Magnetic resonance imaging in Acute Ischemic Stroke

Abstract TMP60: Using CTP based Disconnectome Mapping to identify optimal candidates for endovascular treatment in acute ischemic stroke.

Background: Identifying optimal candidates for endovascular treatment (EVT) remains an ongoing priority to maximize treatment efficacy. The recent large core trials have called into question the use of infarct volume alone for selecting patients. This study aimed at exploring the feasibility of using routinely acquired Computed Tomography Perfusion (CTP) to capture how lesion location impacts brain connectivity and how this in turn affects the ability to benefit from EVT. Methods: Consecutive patients from a multi-centric stroke imaging registry were included in this study if they had a proven anterior circulation large vessel occlusion (LVO) and available baseline CTP data. Hypoperfusion (Tmax >6 seconds) and ischemic core (relative cerebral blood flow <30%) maps were automatically generated using e-CTP (Brainomix, UK) and used to derive disconnection maps via a DTI template. A voxel-based, multivariate method (Sparse Canonical-Correlation-Analysis – LESYMAPS) was used to explore associations between disconnection maps and NIHSS subitems in recanalized patients. The mismatch between Tmax and core disconnection volumes (disconnection mismatch volume) (Figure 1) was used to predict modified Rankin Scale (mRS) at 3-months using an ordinal shift regression adjusted for age, recanalization status and infarct volume. Results: One-hundred and seventy-one patients were included. The median NIHSS was 16 (11.5 to 22). The total NIHSS was associated with disconnection predominantly within the left basal ganglia, brainstem and corpus callosum. Upper and lower limb deficits (NIHSS 5a, 5b, 6a, 6b) were associated with corticospinal tract disconnection, with negative correlations within the contralateral tracts (Figure 2). Language deficits were associated with left hemisphere tract disconnection, also showing negative correlations within the contralateral tracts. The disconnection mismatch volume was an independent predictor of functional outcome at 3-months (Table 1). Conclusion: The results from this study showed that it is possible to use routinely acquired CTP to capture the effects of stroke lesion on brain connectivity and its impact on functional outcome following recanalization treatment. Such an approach could enable more nuanced treatment selection for patients based on specific neurological deficits.

Synthetic MR: Clinical applications in neuroradiology.

Synthetic MR is a quantitative MRI method that measures tissue relaxation times and generates multiple contrast-weighted images using suitable algorithms. The present article principally discusses the multiple dynamic multiple echo (MDME) technique of synthetic MR and briefly describes other quantitative MR sequences. Using illustrative cases, various applications of the MDME sequence in neuroradiology are explained. The MDME sequence allows rapid quantification of tissue relaxation times in a scan duration of 5-7 minutes for full brain coverage. It also has the additional advantages of myelin quantification and automatic segmentation of brain volumes. Applications including reducing scan time, improved detection of demyelinating plaques in Multiple Sclerosis (MS), objective assessment and follow-up for brain atrophy in neurodegenerative MS and dementia cases, and applications in stroke imaging and neuro-oncology are discussed. Uses in the pediatric population, including assessment of brain development and progression of myelination in children, evaluation of white matter disorders, and evaluation of pediatric and adult epilepsy, are elaborated. Quantitative evaluation by synthetic MR is discussed, which allows homogenization and objectification of the radiology data and can serve as a valuable source for artificial intelligence and future multicentre studies. A brief discussion on the technique, other quantitative MR methods, and limitations of the MDME sequence is also presented. The article intends to provide an explicit and comprehensive review of the applications of synthetic MR in neuroradiology, exploring its potential as a routine sequence in daily neuroimaging practice.

Infarct core segmentation using U-Net in CT perfusion imaging: a feasibility study.

The wide variability in thresholds on computed tomography (CT) perfusion parametric maps has led to controversy in the stroke imaging community about the most accurate measurement of core infarction. To investigate the feasibility of using U-Net to perform infarct core segmentation in CT perfusion imaging. CT perfusion parametric maps were the input of U-Net, while the ground truth segmentation was determined based on diffusion-weighted imaging (DWI). The dataset used in this study was from the ISLES2018 challenge, which contains 63 acute stroke patients receiving CT perfusion imaging and DWI within 8 h of stroke onset. The segmentation accuracy of model outputs was assessed by calculating Dice similarity coefficient (DSC), sensitivity, and intersection over union (IoU). The highest DSC was observed in U-Net taking mean transit time (MTT) or time-to-maximum (Tmax) as input. Meanwhile, the highest sensitivity and IoU were observed in U-Net taking Tmax as input. A DSC in the range of 0.2-0.4 was found in U-Net taking Tmax as input when the infarct area contains < 1000 pixels. A DSC of 0.4-0.6 was found in U-Net taking Tmax as input when the infarct area contains 1000-1999 pixels. A DSC value of 0.6-0.8 was found in U-Net taking Tmax as input when the infarct area contains ≥ 2000 pixels. Our model achieved good performance for infarct area containing ≥ 2000 pixels, so it may assist in identifying patients who are contraindicated for intravenous thrombolysis.

Combined Nanodrops Imaging and Ultrasound Localization Microscopy for Detecting Intracerebral Hemorrhage.

Advanced imaging methods are crucial for understanding stroke mechanisms and discovering effective treatments to reduce bleeding and enhance recovery. In pre-clinical in vivo stroke imaging, MRI, CT and optical imaging are commonly used to evaluate stroke outcomes in rodent models. However, MRI and CT have limited spatial resolution for rodent brains, and optical imaging is hindered by limited imaging depth of penetration. Here we introduce a novel contrast-enhanced ultrasound imaging method to overcome these challenges and characterize intracerebral hemorrhage with unique insights. We combined microbubble-based ultrasound localization microscopy (ULM) and nanodrop (ND)-based vessel leakage imaging to achieve simultaneous microvascular imaging and hemorrhage detection. ULM maps brain-wide cerebral vasculature with high spatial resolution and identifies microvascular impairments around hemorrhagic areas. NDs are sub-micron liquid-core particles that can extravasate due to blood-brain barrier breakdown, serving as positive contrast agents to detect hemorrhage sites. Our findings demonstrate that NDs could effectively accumulate in the hemorrhagic site and reveal the location of the bleeding areas upon activation by focused ultrasound beams. ULM further reveals the microvascular damage manifested in the form of reduced vascularity and decreased blood flow velocity across areas affected by the hemorrhagic stroke. The results demonstrate that sequential ULM combined with ND imaging is a useful imaging tool for basic in vivo research in stroke with rodent models where brain-wide detection of active bleeding and microvascular impairment are essential.

Stroke Imaging: An Updated Data for Radiologists and Healthcare Professionals

Stroke Imaging: An Updated Data for Radiologists and Healthcare Professionals

Multimodality cardiac imaging in ischemic stroke: insights into the heart-brain interaction.

Annually, approximately 7.6 million individuals experience a new ischemic stroke, and roughly 25% of all ischemic strokes are cardiogenic in origin, carrying a high risk of recurrence, death and disability. To prevent future ischemic strokes, especially in younger individuals, it is crucial to detect and treat direct and indirect cardioembolic sources. Cardiac imaging is a rapidly evolving field, and post-stroke cardiac imaging is no longer limited to echocardiography, but also includes other imaging techniques, such as cardiac magnetic resonance imaging and cardiac computed tomography. Clinicians must be familiar with numerous cardiac and systemic disorders related to stroke and consider the possibilities that imaging diagnostics have to offer. Additional diagnostics tests, such as pre- and transcranial ultrasound with a bubble test, can also increase the diagnostic accuracy for detecting right-left shunt embolisms. Moreover, a patent foramen ovale (PFO) has traditionally been indicated as a minor or uncertain risk factor for ischemic stroke. However, PFO-associated strokes are a distinct category among the cardioembolic sources as in most cases we do not assume that the thrombus has been developed in-situ in the PFO-structure or elsewhere intracardial, but that PFO merely is acting as a mediator for a paradoxical, venous embolism. The article has two parts: Part I, the heart-brain axis, describes multimodality cardiac imaging in the assessment of cardioembolic sources of ischemic stroke, with a special focus on disorders that traditionally have received little attention in the literature. Part II discusses the brain-heart axis, namely when acute cerebrovascular events lead to cardiac dysfunction, for example neurogenic stunned myocardium and Takotsubo syndrome. Advances in cardiovascular imaging have significantly enhanced the detection of cardiac disorders associated with stroke. Clinicians involved in post stroke work-up need to be aware of the capabilities of different imaging modalities for higher individual diagnostic accuracy in order to effectively treat and prevent stroke recurrence.

The Multicentre Acute ischemic stroke imaGIng and Clinical data (MAGIC) repository: rationale and blueprint.

The Multicentre Acute ischemic stroke imaGIng and Clinical data (MAGIC) repository is a collaboration established in 2024 by seven stroke centres in Europe. MAGIC consolidates clinical and radiological data from acute ischemic stroke (AIS) patients who underwent endovascular therapy, intravenous thrombolysis, a combination of both, or conservative management. All centres ensure accuracy and completeness of the data. Only patients who did not refuse use of their routine data collected during or after their hospital stay are included in the repository. Approvals or waivers are obtained from the responsible ethics committees before data exchange. A formal data transfer agreement (DTA) is signed by all contributing centres. The centres then share their data, and files are stored centrally on a safe server at the University Hospital Zurich. There, patient identifiers are removed and images are algorithmically de-faced. De-identified structured clinical data are connected to the imaging data by a new identifier. Data are made available to participating centres which have entered into a DTA for stroke research projects. Initially, MAGIC is set to comprise initial and first follow-up imaging of 2,500 AIS patients. Clinical data consist of a comprehensive set of patient characteristics and routine prehospital metrics, treatment and laboratory variables. Our repository will support research by leveraging the entire range of routinely collected imaging and clinical data. This dataset reflects the current state of practice in stroke patient evaluation and management and will enable researchers to retrospectively study clinically relevant questions outside the scope of randomized controlled clinical trials. New centres are invited to join MAGIC if they meet the requirements outlined here. We aim to reach approximately 10,000 cases by 2026.

Analyzing temporal imaging patterns in acute ischemic stroke via DICOM-timestamps

Acute stroke management is time-sensitive, making time data crucial for both research and quality management. However, these time data are often not reliably captured in routine clinical practice. In this proof-of-concept study we analysed image-based time data automatically captured in the DICOM format. We enrolled data from two separate stroke centers (n = 3136 and n = 2089). Data from the first center was additionally separated into groups with large-vessel-occlusion (LVO, n = 1.092), medium-vessel-occlusions (MVO, n = 416), and no occlusion (NVO, n = 1630). The DICOM-tag StudyTime was used to analyze the distribution of scan times throughout the day. Additionally, manually documented onset- and admission were extracted from the patients’ records in a subset of cases (n = 347). Timestamps were compared across centers and occlusion groups, and a probabilistic model was developed to illustrate and compare stroke occurrence patterns throughout the day. The temporal distribution of the scan times at both centers was exceptionally consistent with a peak around noon and a nighttime low. The groups with vessel occlusions showed an earlier peak compared to those without (p < 0.04). The median interval between admission and scan time was 23 min, while the median onset-to-imaging time was 1 h:54 min. This proof-of-concept study indicates that DICOM-timestamps can reveal insights into the temporal patterns of stroke imaging and may be a promising tool for quality control and stroke research in general since they are always automatically captured by imaging devices as opposed to manual data collection in routine clinical practice.

Transcranial Cortex-Wide Imaging of Murine Ischemic Perfusion With Large-Field Multifocal Illumination Microscopy.

Ischemic stroke is a common cause of death worldwide and a main cause of morbidity. Presently, laser speckle contrast imaging, x-ray computed tomography, and magnetic resonance imaging are the mainstay for stroke diagnosis and therapeutic monitoring in preclinical studies. These modalities are often limited in terms of their ability to map brain perfusion with sufficient spatial and temporal resolution, thus calling for development of new brain perfusion techniques featuring rapid imaging speed, cost-effectiveness, and ease of use. We report on a new preclinical high-resolution angiography technique for murine ischemic stroke imaging based on large-field high-speed multifocal illumination fluorescence microscopy. We subsequently showcase the proposed method by monitoring therapeutic effects of thrombolysis in stroke (n=6), further performing cross-strain comparison of perfusion dynamics (n=6) and monitoring the therapeutic effects of sensory stimulation-based treatment (n=11). Quantitative readings of hemodynamic and structural changes in cerebral vascular network and pial vessels were attained with 14.4-µm spatial resolution at 80-Hz frame rate fully transcranially. The in vivo perfusion maps accurately delineated the ischemic core and penumbra, further exhibiting a strong correlation (86.1±4.5%) with ex vivo triphenyl tetrazolium chloride staining, significantly higher than for the conventional laser speckle contrast imaging method. Monitoring of therapeutic effects of thrombolysis confirmed that early recanalization could effectively save the penumbra while reducing the infarct area. Cross-strain comparison of perfusion dynamics affirmed that C57BL/6 mice feature a larger penumbra and smaller infarct core as compared with BALB/c mice, which have few or no collaterals. Sensory stimulation-based treatment could effectively enhance blood flow and abolish perfusion deficits in the ischemic core and penumbra regions. A high-speed fluorescence-based angiography method for transcranial stroke imaging in mice is introduced, which is capable of localizing brain perfusion changes and accurately assessing the ischemic penumbra. Compared with the whole-brain x-ray computed tomography and magnetic resonance imaging methods, which are conventionally used for stroke diagnosis and therapeutic monitoring, the new approach is simple and cost-effective, further offering high resolution and speed for in vivo studies. It thus opens new venues for brain perfusion research under various disease conditions such as stroke, neurodegeneration, or epileptic seizures.

Enhancing amide proton transfer imaging in ischemic stroke using a machine learning approach with partially synthetic data.

Amide proton transfer (APT) imaging, a technique sensitive to tissue pH, holds promise in the diagnosis of ischemic stroke. Achieving accurate and rapid APT imaging is crucial for this application. However, conventional APT quantification methods either lack accuracy or are time-consuming. Machine learning (ML) has recently been recognized as a potential solution to improve APT quantification. In this paper, we applied an ML model trained on a new type of partially synthetic data, along with an optimization approach utilizing recursive feature elimination, to predict APT imaging in an animal stroke model. This partially synthetic datum is not a simple blend of measured and simulated chemical exchange saturation transfer (CEST) signals. Rather, it integrates the underlying components including all CEST, direct water saturation, and magnetization transfer effects partly derived from measurements and simulations to reconstruct the CEST signals using an inverse summation relationship. Training with partially synthetic data requires less in vivo data compared to training entirely with fully synthetic or in vivo data, making it a more practical approach. Since this type of data closely resembles real tissue, it leads to more accurate predictions than ML models trained on fully synthetic data. Results indicate that an ML model trained on this partially synthetic data can successfully predict the APT effect with enhanced accuracy, providing significant contrast between stroke lesions and normal tissues, thus clearly delineating lesions. In contrast, conventional quantification methods such as the asymmetric analysis method, three-point method, and multiple-pool model Lorentzian fit showed inadequate accuracy in quantifying the APT effect. Moreover, ML methods trained using in vivo data and fully synthetic data exhibited poor predictive performance due to insufficient training data and inaccurate simulation pool settings or parameter ranges, respectively. Following optimization, only 13 frequency offsets were selected from the initial 69, resulting in significantly reduced scan time.

End-to-End Stroke Imaging Analysis Using Effective Connectivity and Interpretable Artificial Intelligence

End-to-End Stroke Imaging Analysis Using Effective Connectivity and Interpretable Artificial Intelligence

High-Risk Embolic Sources on Cardiac Computed Tomography in Patients With Acute Ischemic Stroke: A Case-Control Study.

Cardiac computed tomography (CT) is increasingly used to search for cardioembolic sources of acute ischemic stroke (AIS). We assessed the association between high-risk cardioembolic sources on cardiac CT and AIS. We performed a case-control study using data from a prospective cohort including consecutive adult patients with suspected stroke who underwent cardiac CT acquired during the initial stroke imaging protocol between 2018 and 2020. Cases were patients with a final diagnosis of AIS. Controls were patients with a stroke mimic (SMi). We excluded patients with a transient ischemic attack. Diagnoses were established by an adjudication committee. Cardiac radiologists assessed the presence of structural high-risk sources of cardioembolism according to predefined criteria. We used the Firth penalized likelihood method to perform a logistic regression, adjusted for age, sex, and history of myocardial infarction to determine the association between high-risk embolic sources and AIS. For the primary analysis, we excluded patients with a history of atrial fibrillation. In a secondary analysis, patients with known atrial fibrillation were included. Of 774 patients, we excluded 167 patients due to no written informed consent or the diagnosis of transient ischemic attack. Of 607 patients, 107 patients had known atrial fibrillation and were excluded from the primary analysis. Of 500 included patients, 375 had AIS (75%, median age 70, 61% male) and 125 SMi (25%, median age 69, 42% male). A high-risk cardioembolic source was found on CT in 32/375 (8.5%) patients with AIS and 0/125 (0%) patients with SMi (adjusted odds ratio, 23.8 [95% CI, 3.3-3032.5]). Cardiac thrombi were the most commonly observed abnormality, present in 23 (6.1%) patients with AIS and 0 (0%) patients with SMi. A high-risk source of cardioembolism was detected on cardiac CT more frequently in patients with AIS than in patients with SMi. These data substantiate the clinical relevance of cardioembolic sources detected on acute cardiac CT in patients with ischemic stroke.

Recent advances in portable, low-field magnetic resonance imaging in cerebrovascular disease.

This review aims to describe recent advances in low-field (0.064 T) magnetic resonance imaging (LF-MRI) of cerebrovascular disease, including ischemic and hemorrhagic stroke and white matter hyperintensities. Since 2023, several studies have highlighted the rapidly changing landscape of portable, low-field MRI (LF-MRI) and its applications in stroke and cerebrovascular disease. The advantages of using LF-MRI in these settings are multifold: cheaper and dynamic imaging of this patient population confers closer observation during the acute and chronic stages of cerebrovascular disease. Initial deployments of the device span a variety of acute and emergency settings, including imaging around thrombolytic administration, endovascular reperfusion, intracerebral hemorrhage management, and cardiovascular intensive care. LF-MRI also has an important role in cerebrovascular disease monitoring and prevention, namely white matter hyperintensity (WMH) progression and vascular and Alzheimer's dementia. Early studies suggest reliable sensitivity and specificity for these pathologies. With further improvements to LF-MRI hardware, software and postprocessing on the horizon, we anticipate the device's ability to provide inexpensive and flexible neuroimaging to a wide array of healthcare settings that treat, prevent, and manage cerebrovascular disease. Recent studies indicate that LF-MRI promotes rapid, cost-effective, and clinically useful neuroimaging at various clinical timepoints throughout stroke and cerebrovascular disease progression and management.

Diffusion-weighted MR imaging of acute stroke: correlation with T2-weighted and magnetic susceptibility-enhanced MR imaging in cats.

Diffusion-weighted MR imaging of acute stroke: correlation with T2-weighted and magnetic susceptibility-enhanced MR imaging in cats.

Multi‐ancestry Genome‐wide Gene‐Vascular Risk Factors Interaction Analyses in Alzheimer’s Disease

AbstractBackgroundCardio and cerebrovascular risk factors (CVRFs) increase the risk of cerebrovascular disease and clinical Alzheimer’s Disease (AD), and over 70% of the patients with AD coincident cerebrovascular pathology. We previously found that FMNL2 interacts with a burden score of hypertension, diabetes, heart disease, and body mass index (BMI) by altering the normal astroglial‐vascular mechanisms that underly amyloid clearance. Stroke, defined by history of a clinical stroke or brain imaging, is a moderately robust risk factor for AD and dementia. The goal here was to identify genes that interact with CVRFs, incorporating stroke as an additional factor, on AD in multi‐ethnic cohorts.MethodWe conducted a genome‐wide gene‐CVRF score interaction analysis for AD, in 7,939 AD patients and 9,631 controls from eight multi‐ethnic cohorts of non‐Hispanic Whites, African Americans, and Hispanics including ADNI, NACC, NOMAS, WHICAP, EFIGA, and ROSMAP. A CVRF score was created from the first principal component of history of clinical stroke, hypertension, diabetes, and heart disease, and measured BMI. Gene‐based interaction test was performed with the adaptive gene‐environment interaction test. Results were summarized using a meta‐analysis. We investigated the association of pathological AD, amyloid‐β, or brain infarcts with gene expression and protein expression from the frontal cortex in ROSMAP using a generalized linear model. Age, sex, and the first three principal components were adjusted in the models.ResultThe interaction of CVRF score with FMNL2 on AD (p = 1.02E‐05) was identified and additional genes were identified to interact with CVRF score, including SLC22A14 (p = 1.44E‐06), AMMECR1L (p = 2.74E‐06), PRG3 (p = 2.76E‐06), CFAP99 (p = 5.22E‐06), ADPGK‐AS1 (p = 8.58E‐06) and BRINP1 (p = 6.29E‐06). ADPGK‐AS1 and FMNL2 gene expressions were associated with pathological AD (p = 0.004 and p = 0.0002). FMNL2 and BRINP1 gene expressions were higher in the brains of patients with brain infarcts (p = 0.025 and p = 0.006). BRINP1 protein expression was associated with pathological AD (p = 0.0002) and was higher in the brains of patients with brain infarcts (p = 0.022).ConclusionWe identified novel candidate genes that interact with CVRFs on AD in multi‐ethnic cohorts. Understanding the interplay between genes, CVRFs, and AD has the potential to reveal novel molecular targets for prevention and treatment for AD.

A stroke imaging protocol in patients with a history of contrast-induced anaphylaxis.

The need for emergent, contrast-enhanced neuroimaging in stroke patients with a history of severe reaction to iodinated contrast represents a unique dilemma in emergency departments. There is currently a lack of evidence-based management protocols for these cases. We describe a protocol established at our institution, based off American College of Radiology (ACR) guidelines and institutional experience, to guide decision-making in these scenarios.