Imaging of acute stroke prior to treatment: current practice and evolving techniques

Diagnostic Accuracy of Hyperdense Artery Sign in Early Detection of Middle Cerebral Artery Infarction: A Cross-Sectional Validation Study

Background

Hyperdense middle cerebral artery sign (HMCAS) on a non-enhanced multidetector computed tomography (MDCT) scan is considered an important radiological marker in detecting acute arterial thrombotic occlusion, and it is one of the earliest signs of ischemic cerebrovascular accident (CVA). This finding has been observed within 90 min of symptom onset. Modern approaches to patients with cerebral infarction emphasize early diagnosis and management.

Purpose

To determine the diagnostic accuracy of hyperdense artery signs in early detection of middle cerebral artery (MCA) infarction on non-contrast-enhanced MDCT scan using Magnetic Resonance Angiography (MRA) within 24 h as the gold standard for definitive diagnosis.

Method

A total of 140 patients aged 35-70 years, referred to the radiology department of Aga Khan University Hospital with clinical suspicion of acute cerebral infarction, were included. After clinical suspicion of acute infarction, the patient underwent an initial complete MDCT scan of the brain, which was performed using Aquilion ONE 640 slice MDCT (Toshiba Medical Systems, Japan). Consultant radiologists, with a minimum of 5 years of experience in MDCT brain imaging, interpreted the images. Follow-up examination with MRA within 24 h was performed to confirm the diagnosis of MCA infarction.

Results

Overall sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of HMCAS in the early detection of MCA infarction on non-contrast-enhanced MDCT scan using MRA as the gold standard for definitive diagnosis was 96.20%, 93.44%, 95.0%, 95.0%, and 95.0%, respectively.

Conclusion

This study concluded that the diagnostic accuracy of hyperdense artery signs in the early detection of MCA infarction on non-contrast-enhanced MDCT scans is very high.

A comparison of lesion mapping analyses based on CT versus MR imaging in stroke

It is commonly asserted that MRI-derived lesion masks outperform CT-derived lesion masks in lesion-mapping analysis. However, no quantitative analysis has been conducted to support or refute this claim. This study reports an objective comparison of lesion-mapping analyses based on CT- and MRI-derived lesion masks to clarify how input imaging type may ultimately impact analysis results. Routine CT and MRI data were collected from 85 acute stroke survivors. These data were employed to create binarized lesion masks and conduct lesion-mapping analyses on simulated behavioral data. Following standard lesion-mapping analysis methodology, each voxel or region of interest (ROI) were considered as the underlying "target" within CT and MRI data independently. The resulting thresholded z-maps were compared between matched CT- and MRI-based analyses. Paired MRI- and CT-derived lesion masks were found to exhibit significant variance in location, overlap, and size. In ROI-level simulations, both CT and MRI-derived analyses yielded low Dice similarity coefficients, but CT analyses yielded a significantly higher proportion of results which overlapped with target ROIs. In single-voxel simulations, MRI-based lesion mapping was able to include more voxels than CT-based analyses, but CT-based analysis results were closer to the underlying target voxel. Simulated lesion-symptom mapping results yielded by paired CT and MRI lesion-symptom mapping analyses demonstrated moderate agreement in terms of Dice coefficient when systematic differences in cluster size and lesion overlay are considered. Overall, these results suggest that CT and MR-derived lesion-symptom mapping results do not reliably differ in accuracy. This finding is critically important as it suggests that future studies can employ CT-derived lesion masks if these scans are available within the appropriate time-window.

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.

Recurrence of ischaemic stroke using epidemiology and neuroimaging: A retrospective study in Gansu Province

Objectives

This retrospective study aimed to investigate the clinical and imaging recurrence of ischaemic stroke (IS), and to evaluate the risk factors for recurrence. A combined clinical and imaging diagnostic model is important for stroke prevention and management.

Methods and materials

In accordance with the inclusion and exclusion criteria, we retrospectively analysed consecutively hospitalised patients with acute IS at the Affiliated Hospital of Gansu University of Chinese Medicine. Based on the epidemiological and imaging results, stroke episodes were divided into four categories: clinical first episode (CFE), clinical recurrence (CR), imaging first episode (IFE), and imaging recurrence (IR). Based on the above categories and clinical practice, a joint diagnostic system for IS was established for the first time, including the following five types: IFE, IR, CFE and IFE, CFE and IR, and CR and IR. A binomial logistic regression analysis was conducted to determine the factors which contributed to CR and IR.

Results

In total, 280 patients were assessed. The CR rate was 22.9% (64/280) and the IR rate was 62.9% (176/280). The only predictor of CR was hypertension (P = 0.019, odds ratio [OR] = 3.041, 95% confidence interval [95%CI] = 1.200-7.704). The factors of hypertension (P < 0.001, OR = 3.551, 95%CI = 1.781-7.080) and age (P = 0.031, OR = 1.031, 95%CI = 1.003-1.060) were predictors of IR.

Conclusion

The IR rates for IS were three times higher than the CR rates. The key to preventing IR and CR in IS was the management of blood pressure. Neuroimaging examinations were important for the early detection of IFE and IR in elderly patients with hypertension. A combined clinical imaging diagnostic model was developed for the first time.

Time to CT scan for patients with acute severe neurological symptoms: a quality assurance study

Emergent brain computed tomography (CT) scan allows for identification of patients presenting with acute severe neurological symptoms in whom medical and surgical interventions may be lifesaving. The aim of this study was to evaluate if time to CT from arrival at the emergency department exceeded 30 min in patients admitted with acute severe neurological symptoms. This was a retrospective register-based quality assurance study. We identified patients admitted to the emergency department with acute severe neurological symptoms between April 1st, 2016 and September 30th, 2020. Data were retrieved from the registry of acute medical team activations. We considered that time to CT from arrival at the emergency department should not exceed 30 min in more than 10% of patients. A total of 559 patients were included. Median time from arrival at the emergency department until CT scan was 24 min (IQR 16–35) in children (< 18 years), 10 min (IQR 7–17) for adults (18–59 years), and 11 min (IQR 7–16) for elders (> 60 years). This time interval exceeded 30 min for 8.2% (95% CI 6.1–10.9) of all included patients, 35.3% of children, 5.9% of adults, and 8.6% of elders. No children died within 30 days. The 30-day mortality was 21.3% (95% CI 16.4–27) in adults, and 43.9% (95% CI 38.2–49.8) in elders. Time from arrival at our emergency department until brain CT scan exceeded 30 min in 8.2% of all included patients but exceeded the defined quality aim in children and could be improved.

Subcortical-cortical dynamical states of the human brain and their breakdown in stroke

The mechanisms controlling dynamical patterns in spontaneous brain activity are poorly understood. Here, we provide evidence that cortical dynamics in the ultra-slow frequency range (<0.01–0.1 Hz) requires intact cortical-subcortical communication. Using functional magnetic resonance imaging (fMRI) at rest, we identify Dynamic Functional States (DFSs), transient but recurrent clusters of cortical and subcortical regions synchronizing at ultra-slow frequencies. We observe that shifts in cortical clusters are temporally coincident with shifts in subcortical clusters, with cortical regions flexibly synchronizing with either limbic regions (hippocampus/amygdala), or subcortical nuclei (thalamus/basal ganglia). Focal lesions induced by stroke, especially those damaging white matter connections between basal ganglia/thalamus and cortex, provoke anomalies in the fraction times, dwell times, and transitions between DFSs, causing a bias toward abnormal network integration. Dynamical anomalies observed 2 weeks after stroke recover in time and contribute to explaining neurological impairment and long-term outcome.

Favaretto et al. show that the brain rapidly alternates between transient connectivity patterns, with cortical regions flexibly synchronizing with two groups of subcortical regions, and that this dynamic is abnormal in stroke patients.

Prediction model of early biomarkers of massive cerebral infarction caused by anterior circulation occlusion: Establishment and evaluation

Objective

The purpose of this study is to establish and evaluate an early biomarker prediction model of massive cerebral infarction caused by anterior circulation occlusion.

Methods

One hundred thirty-four patients with acute cerebral infarction from January 2018 to October 2020 were selected to establish the development cohort for the internal test of the nomogram. Ninety-one patients with acute cerebral infarction hospitalized in our hospital from December 2020 to December 2021 were constituted the validation cohort for the external validation. All patients underwent baseline computed tomography (CT) scans within 12 h of onset and early imaging signs (hyperdense middle cerebral artery sign, obscuration of the lentiform nucleus, insular ribbon sign) of acute cerebral infarction were identified on CT by two neurologists. Based on follow-up CT images, patients were then divided into a massive cerebral infarction group and a non-massive cerebral infarction group. The nomogram model was constructed based on logistic regression analysis with R language. The nomogram was subsequently validated in an independent external validation cohort. Accuracy and discrimination of the prediction model were evaluated by a calibration chart, receiver operating characteristic (ROC) curve, and decision curve.

Results

The indicators, including insular ribbon sign, reperfusion therapy, National Institutes of Health Stroke Scale (NHISS) score, previous cerebral infarction, and atrial fibrillation, were entered into the prediction model through binary logistic regression analysis. The prediction model showed good predictive ability. The area under the ROC curve of the prediction model was 0.848. The specificity, sensitivity, and Youden index were 0.864, 0.733, and 0.597, respectively. This nomogram to the validation cohort also showed good discrimination (AUC = 0.940, 95% CI 0.894–0.985) and calibration.

Conclusion

Demonstrating favorable predictive efficacy and reproducibility, this study successfully established a prediction model of CT imaging signs and clinical data as early biomarkers of massive cerebral infarction caused by anterior circulation occlusion.

Toward automatic reformation at the orbitomeatal line in head computed tomography using object detection algorithm

Consistent cross-sectional imaging is desirable to accurately detect lesions and facilitate follow-up in head computed tomography (CT). However, manual reformation causes image variations among technologists and requires additional time. We therefore developed a system that reformats head CT images at the orbitomeatal (OM) line and evaluated the system performance using real-world clinical data. Retrospective data were obtained for 681 consecutive patients who underwent non-contrast head CT. The datasets were randomly divided into one of three sets for training, validation, or testing. Four landmarks (bilateral eyes and external auditory canal) were detected with the trained You Look Only Once (YOLO)v5 model, and the head CT images were reformatted at the OM line. The precision, recall, and mean average precision at the intersection over union threshold of 0.5 were computed in the validation sets. The reformation quality in testing sets was evaluated by three radiological technologists on a qualitative 4-point scale. The precision, recall, and mean average precision of the trained YOLOv5 model for all categories were 0.688, 0.949, and 0.827, respectively. In our environment, the mean implementation time was 23.5 ± 2.4 s for each case. The qualitative evaluation in the testing sets showed that post-processed images of automatic reformation had clinically useful quality with scores 3 and 4 in 86.8%, 91.2%, and 94.1% for observers 1, 2, and 3, respectively. Our system demonstrated acceptable quality in reformatting the head CT images at the OM line using an object detection algorithm and was highly time efficient.

Application of MAGnetic resonance imaging compilation in acute ischemic stroke

BACKGROUND

Synthetic magnetic resonance imaging (MRI) MAGnetic resonance imaging compilation (MAGiC) is a new MRI technology. Conventional T1, T2, T2-fluid-attenuated inversion recovery (FLAIR) contrast images, quantitative images of T1 and T2 mapping, and MAGiC phase sensitive inversion recovery (PSIR) Vessel cerebrovascular images can be obtained simultaneously through post-processing at the same time after completing a scan. In recent years, studies have reported that MAGiC can be applied to patients with acute ischemic stroke. We hypothesized that the synthetic MRI vascular screening scheme can evaluate the degree of cerebral artery stenosis in patients with acute ischemic stroke.

AIM

To explore the application value of vascular images obtained by synthetic MRI in diagnosing acute ischemic stroke.

METHODS

A total of 64 patients with acute ischemic stroke were selected and examined by MRI in the current retrospective cohort study. The scanning sequences included traditional T1, T2, and T2-FLAIR, three-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA), diffusion-weighted imaging (DWI), and synthetic MRI. Conventional contrast images (T1, T2, and T2-FLAIR) and intracranial vessel images (MAGiC PSIR Vessel] were automatically reconstructed using synthetic MRI raw data. The contrast-to-noise ratio (CNR) values of traditional T1, T2, and T2-FLAIR images and MAGiC reconstructed T1, T2, and T2-FLAIR images in DWI diffusion restriction areas were measured and compared. MAGiC PSIR Vessel and TOF MRA images were used to measure and calculate the stenosis degree of bilateral middle cerebral artery stenosis areas. The consistency of MAGiC PSIR Vessel and TOF MRA in displaying the degree of vascular stenosis with computed tomography angiography (CTA) was compared.

RESULTS

Among the 64 patients with acute ischemic stroke, 79 vascular stenosis areas showed that the correlation between MAGiC PSIR Vessel and CTA (r = 0.90, P < 0.01) was higher than that between TOF MRA and CTA (r = 0.84, P < 0.01). With a degree of vascular stenosis > 50% assessed by CTA as a reference, the area under the receiver operating characteristic (ROC) curve of MAGiC PSIR Vessel [area under the curve (AUC) = 0.906, P < 0.01] was higher than that of TOF MRA (AUC = 0.790, P < 0.01). Among the 64 patients with acute ischemic stroke, 39 were scanned for traditional T1, T2, and T2-FLAIR images and MAGiC images simultaneously, and CNR values in DWI diffusion restriction areas were measured, which were: Traditional T2 = 21.2, traditional T1 = -6.7, and traditional T2-FLAIR = 11.9; and MAGiC T2 = 7.1, MAGiC T1 = -3.9, and MAGiC T2-FLAIR = 4.5.

CONCLUSION

The synthetic MRI vascular screening scheme for patients with acute ischemic stroke can accurately evaluate the degree of bilateral middle cerebral artery stenosis, which is of great significance to early thrombolytic interventional therapy and improving patients' quality of life.

Contemporary Neuroprotection Strategies during Cardiac Surgery: State of the Art Review

Open-heart surgery is the leading cause of neuronal injury in the perioperative state, with some patients complicating with cerebrovascular accidents and delirium. Neurological fallout places an immense burden on the psychological well-being of the person affected, their family, and the healthcare system. Several randomised control trials (RCTs) have attempted to identify therapeutic and interventional strategies that reduce the morbidity and mortality rate in patients that experience perioperative neurological complications. However, there is still no consensus on the best strategy that yields improved patient outcomes, such that standardised neuroprotection protocols do not exist in a significant number of anaesthesia departments. This review aims to discuss contemporary evidence for preventing and managing risk factors for neuronal injury, mechanisms of injury, and neuroprotection interventions that lead to improved patient outcomes. Furthermore, a summary of existing RCTs and large observational studies are examined to determine which strategies are supported by science and which lack definitive evidence. We have established that the overall evidence for pharmacological neuroprotection is weak. Most neuroprotective strategies are based on animal studies, which cannot be fully extrapolated to the human population, and there is still no consensus on the optimal neuroprotective strategies for patients undergoing cardiac surgery. Large multicenter studies using universal standardised neurological fallout definitions are still required to evaluate the beneficial effects of the existing neuroprotective techniques.

The middle cerebral artery density and ratio for the diagnosis of acute ischaemic stroke in the Emergency Department

PURPOSE

Non-contrast computed tomography (ncCT) is the first-line imaging modality for acute ischaemic stroke diagnosis. Recognition of the early diagnostic signs of a stroke on computed tomography (CT) is crucial. The hyperdense middle cerebral artery (MCA) sign is one of these findings. We investigated the diagnostic utility of absolute MCA density (MCAD) in patients with acute MCA stroke confirmed with diffusion-weighted magnetic resonance imaging (dwMRI).

METHODS

We retrospectively included all patients who presented to the Emergency Department with symptoms related to an acute stroke and confirmed with a dwMRI and ncCT to this diagnostic case-control study. An expert radiologist with more than four years of experience in neuroradiology re-evaluated all ncCT images. The evaluation of MCAD and ratio were measured on axial images in Hounsfield units (HU).

RESULTS

We included 407 patients in our study (MCA infarction: 55%, n = 225; Control: 45%, n = 182). We calculated the threshold for the highest sensitivity (20%) and specificity (94%) as 49 HU with the Youden J index test for MCAD and as 1.1 for MCAD ratio (sensitivity 20% and specificity 95%). MCAD >49 HU or MCAD ratio >1.1 alone or joint use of MCAD >47 HU and MCAD ratio >1.1 are useful markers to confirm the diagnosis of MCA AIS with a specificity of at least 94%. Higher MCAD values are associated with larger infarction volumes.

CONCLUSION

MCAD and MCAD ratio can be used to identify patients who need early treatment, especially in situations where computed tomography angiogram or dwMRI are not readily available.

Image Features of Magnetic Resonance Angiography under Deep Learning in Exploring the Effect of Comprehensive Rehabilitation Nursing on the Neurological Function Recovery of Patients with Acute Stroke

This study was to explore the effects of imaging characteristics of magnetic resonance angiography (MRA) based on deep learning on the comprehensive rehabilitation nursing on the neurological recovery of patients with acute stroke. In this study, 84 patients with acute stroke who were treated in hospital were selected as the research objects, and they were rolled into a control group (routine care) and an experimental group (comprehensive rehabilitation care). The dense dilated block-convolution neural network (DD-CNN) algorithm under deep learning for cerebrovascular was adopted to assess the effect of comprehensive rehabilitation care on the neurological recovery of patients with acute stroke. The results showed that the Berg scale scores, Fugl-Meyer scores, and Functional Independence Measure (FIM) scores of the experimental group of patients after 6 weeks and 12 weeks of comprehensive rehabilitation nursing were greatly different from those before treatment, showing statistical differences (P < 0.05). Compared with conventional magnetic resonance imaging (MRI) images, MRA images based on CNN algorithm, Dense Net algorithm, and DD-CNN algorithm can more clearly show the patient's cerebral artery occlusion. The average dice similarity coefficient (DSC) values of CNN algorithm, Dense Net algorithm, and DD-CNN algorithm were determined to be 84.3%, 95.7%, and 97.8%, respectively; the average sensitivity (Sen) values of the three algorithms were 76.1%, 95.4%, and 96.8%, respectively; and the average accuracy (Acc) values were 87.9%, 96.3%, and 97.9%, respectively. Thus, there were statistically obvious differences among the three algorithms in terms of average values of DSC, Sen, and Acc (P < 0.05). The MRA images processed by the DD-CNN algorithm showed that the degree of neurological recovery of the experimental group was observably greater than that of the control group, and the difference was statistically obvious (P < 0.05). In short, the image features of MRA based on the deep learning DD-CNN algorithm showed good application value in studying the effect of comprehensive rehabilitation nursing on the neurological recovery of patients with acute stroke, and it was worthy of promotion.

MRI as a first-line imaging modality in acute ischemic stroke: a sustainable concept

Background:

Computed tomography (CT) scans are the first-line imaging technique in acute stroke patients based on the argument of rapid feasibility. Using magnetic resonance imaging (MRI) as the first-line imaging technique is the exception to the rule, although it provides much more diagnostic information and avoids exposure to radiation. We evaluated whether an MRI-based acute stroke concept is fast, suitable, and useful to improve recanalization rates and patient outcomes.

Methods:

We performed a retrospective observational cohort study comparing patients treated at a comprehensive stroke center (Ulm/Germany) applying an MRI-based acute stroke concept with patients recorded in a large comprehensive stroke registry in Baden-Württemberg (Germany). We analyzed the quality indicators of acute stroke treatment, patient’s outcome, and the rate of transient ischemic attack (TIA) at discharge.

Results:

A total of 2182 patients from Ulm and 82,760 patients from the Baden-Württemberg (BW) stroke registry (including 29,575 patients of comprehensive stroke centers (BWc)) were included. Intravenous thrombolysis rate was higher in Ulm than in BW or the BWc stroke centers (Ulm 27.4% versus BW 20.9% versus BWc 26.1; p < 0.01), while a door-to-needle time <30 min could be achieved more frequently (Ulm 73.6% versus BW 44.1% versus BWc 47.1%; p < 0.01). Thrombectomy rate in patients with a proximal vascular occlusion was higher (Ulm 69.2% versus BW 50.7% versus BWc 59.3; p < 0.01). The number of TIA diagnoses was lower (Ulm 16.2% versus BW 24.6% versus BWc 19.9%; p < 0.01). More patients showed a shift to a favorable outcome (Ulm 21.1% versus BW 16.9% versus BWc 15.3; p < 0.01). Complication rates were similar.

Conclusions:

The MRI-based acute stroke concept is suitable, fast and seems to be beneficial. The time-dependent quality indicators were better both in comparison to all stroke units and to the comprehensive stroke units in the area. Based on the MRI concept, high rates of recanalization procedures and fewer TIA diagnoses could be observed. In addition, there was a clear trend towards an improved clinical outcome. A clinical trial comparing the effects of CT and MRI as the primary imaging technique in otherwise identical stroke unit settings is warranted.

Research Progress of Deep Learning in the Diagnosis and Prevention of Stroke

In order to evaluate the importance of deep learning techniques in stroke diseases, this paper systematically reviews the relevant literature. Deep learning techniques have a significant impact on the diagnosis, treatment, and prediction of stroke. In addition, this study also discusses the current bottlenecks and the future development prospects of deep learning technology.

Secondary Stroke Prevention After Ischemic Stroke in Patients with Alzheimer's Disease and Other Dementia Disorders

Background:

Recurrent ischemic stroke (IS) increases the risk of cognitive decline. To lower the risk of recurrent IS, secondary prevention is essential.

Objective:

Our aim was to compare post-discharge secondary IS prevention and its maintenance up to 3 years after first IS in patients with and without Alzheimer’s disease and other dementia disorders.

Methods:

Prospective open-cohort study 2007–2014 from the Swedish national dementia registry (SveDem) and the Swedish national stroke registry (Riksstroke). Patients with dementia who experienced an IS (n = 1410; 332 [23.5%] with Alzheimer’s disease) were compared with matched non-dementia IS patients (n = 7150). We analyzed antiplatelet, anticoagulant, blood pressure lowering, and statin treatment as planned medication initiation at discharge and actual dispensation of medications at first, second, and third year post-stroke.

Results:

At discharge, planned initiation of medication was higher in patients with dementia compared to non-dementia patients for antiplatelets (OR with 95% CI for fully adjusted models 1.23 [1.02–1.48]) and lower for blood pressure lowering medication (BPLM; 0.57 [0.49–0.67]), statins (0.57 [0.50–0.66]), and anticoagulants (in patients with atrial fibrillation – AF; 0.41 [0.32–0.53]). When analysis for antiplatelets was stratified according to the presence of AF, ORs for receiving antiplatelets remained significant only in the presence of AF (in the presence of AF 1.56 [1.21–2.01], in patients without AF 0.99 [0.75–1.33]). Similar trends were observed in 1st, 2nd, and 3rd year post-stroke.

Conclusions:

Dementia was a predictor of lower statin and BPLM use. Patients with dementia and AF were more likely to be prescribed antiplatelets and less likely to receive anticoagulants.

Non-Coding RNAs Based Molecular Links in Type 2 Diabetes, Ischemic Stroke, and Vascular Dementia

This article reviews recent advances in the study of microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and their functions in type 2 diabetes mellitus (T2DM), ischemic stroke (IS), and vascular dementia (VaD). miRNAs and lncRNAs are gene regulation markers that both regulate translational aspects of a wide range of proteins and biological processes in healthy and disease states. Recent studies from our laboratory and others have revealed that miRNAs and lncRNAs expressed differently are potential therapeutic targets for neurological diseases, especially T2DM, IS, VaD, and Alzheimer's disease (AD). Currently, the effect of aging in T2DM, IS, and VaD and the cellular and molecular pathways are largely unknown. In this article, we highlight results from the works on the molecular connections between T2DM and IS, and IS and VaD. In each disease, we also summarize the pathophysiology and the differential expressions of miRNAs and lncRNAs. Based on current research findings, we hypothesize that 1) T2DM bi-directionally and age-dependently induces IS and VaD, and 2) these changes are precursors to the onset of dementia in elderly people. Research into these hypotheses is required to examine further whether research efforts on reducing T2DM, IS, and VaD may affect dementia and/or delay the AD disease process in the aged population.

Hyperdense middle cerebral artery sign in large cerebral infarction

OBJECTIVES

To evaluate if the hyperdense middle cerebral artery sign (HMCAS) is an imaging biomarker for hemorrhagic transformation (HT) and the functional outcome of patients with large cerebral infarctions without thrombolytic therapy.

MATERIALS AND METHODS

The clinical and imaging data of 312 patients with large cerebral infarction without thrombolytic therapy were retrospectively analyzed. They were divided into patients who presented with HMCAS (n = 121) and those who did not (non-HMCAS[n = 168] patients), and the clinical data of the 2 groups were compared. This was a retrospective study.

RESULTS

Of the 289 patients, 83(28.7%) developed HT. The incidence of atrial fibrillation, high homocysteine and admission NIHSS score at the time of admission was significantly higher in the HMCAS patients than in non-HMCAS patients (p < .05). The ASPECTS was significantly lower in HMCAS patients (t = -5.835, p < .001). The incidence of PH-2 and 3-month mRS score was also statistically significant higher in HMCAS patients (χ²  = 3.971, p = .046; χ²  = 5.653, p < .001, respectively). A sub-analysis showed HMCAS patients with HT were significantly older than non-HMCAS patients with HT (t = 2.473, p = .015). The incidence of atrial fibrillation and the 3-month mortality rate were higher in HMCAS patients with HT than in non-HMCAS patients with HT (χ²  = 3.944, p = .047; χ²  = 6.043, p = .014, respectively). Multiple logistic regression analysis showed HT was independently associated with HMCAS (adjusted OR/95% CI/p = 2.762/1.571-4.854/p < .001) and admission NIHSS score (adjusted OR/95% CI/p = 1.081/1.026-1.139/0.003). And HMCAS with HT was independently associated with length of HMCAS (adjusted OR/95% CI/p = 1.216/1.076-1.374/0.002).

CONCLUSIONS

HMCAS in patients with a large cerebral infarction without thrombolytic therapy is an independent biomarker of HT. Length of HMCAS is also a marker of HT with lower ASPECTS in HMCAS patients.

Evaluating the use of gradient echo imaging for the detection of cerebral microbleeds in acute stroke cases: A retrospective data analysis in a UK stroke unit

INTRODUCTION

Imaging in stroke, allows its classification into ischaemic stroke (IS) or intracranial haemorrhagic stroke (ICH), ensuring time-sensitive treatment to be administered. Imaging can also allow detection of cerebral microbleeds (CMBs), which may further determine pharmacological intervention in acute stroke. True gradient echo (T2∗GRE) or susceptibility weighted imaging (SWI) have high sensitivity for the detection of CMBs. These two sequences are included in the national guidelines; however, the implementation of these guidelines can vary depending on local interpretation and scanner capabilities.

AIM

To explore the use and application of blood sensitive MRI sequences in a specialist UK stroke unit for the detection of CMBs, to improve local practice.

METHODS

A retrospective data analysis of the native database, spanning a 6-month period, was used. The data of 281 acute stroke patients with an MRI were reviewed and analysed. The MRI sequences applied, and the final diagnosis were noted for each case.

RESULTS

Of the 281 acute stroke patients with MRI, 259 (92.1%) had an IS, 16 (5.68%) an ICH and 6 (2.14%) had both. Overall, 13 (4.63%) had a CMB diagnosis. All of these 13 patients had a true T2∗GRE sequence. CMBs were not detected in the absence of a T2∗GRE sequence.

CONCLUSION

T2∗GRE imaging is essential for detecting CMBs. When omitted, CMB incidence can be considerably lower than that suggested in the literature. Missing CMB diagnoses in stroke patients may result in suboptimal treatment pathways, compromising the patients' standard of care.

IMPLICATIONS FOR PRACTICE

When SWI is not available, it is imperative to always include a true T2∗GRE sequence to detect microbleeds in suspected acute stroke cases.

Neuroimaging and deep learning for brain stroke detection - A review of recent advancements and future prospects

BACKGROUND AND OBJECTIVE

In recent years, deep learning algorithms have created a massive impact on addressing research challenges in different domains. The medical field also greatly benefits from the use of improving deep learning models which save time and produce accurate results. This research aims to emphasize the impact of deep learning models in brain stroke detection and lesion segmentation. This is achieved by discussing the state of the art approaches proposed by the recent works in this field.

METHODS

In this study, the advancements in stroke lesion detection and segmentation were focused. The survey analyses 113 research papers published in different academic research databases. The research articles have been filtered out based on specific criteria to obtain the most prominent insights related to stroke lesion detection and segmentation.

RESULTS

The features of the stroke lesion vary based on the type of imaging modality. To develop an effective method for stroke lesion detection, the features need to be carefully extracted from the input images. This review takes an attempt to categorize and discuss the different deep architectures employed for stroke lesion detection and segmentation, based on the underlying imaging modality. This further assists in understanding the relevance of the two-deep neural network components in medical image analysis namely Convolutional Neural Network (CNN) and Fully Convolutional Network (FCN). It hints at other possible deep architectures that can be proposed for better results towards stroke lesion detection. Also, the emerging trends and breakthroughs in stroke detection have been detailed in this evaluation.

CONCLUSION

This work concludes by examining the technical and non-technical challenges faced by researchers and indicate the future implications in stroke detection. It could support the bio-medical researchers to propose better solutions for stroke lesion detection.

Ischemic stroke with a preceding Trans ischemic attack (TIA) less than 24 hours and thrombolytic therapy

Background

Acute ischemic stroke attack with and without a recent TIA may differ in clinical risk factors, and this may affect treatment outcomes following thrombolytic therapy. We examined whether the odds of exclusion or inclusion for thrombolytic therapy are greater in ischemic stroke with TIA less than 24 h preceding ischemic stroke (recent-TIA) as compared to those without recent TIA or non-TIA > 24 h and less than 1 month (past-TIA).

Methods

A retrospective hospital-based analysis was conducted on 6315 ischemic stroke patients, of whom 846 had proven brain diffusion-weighted magnetic resonance imaging (DW-MRI) of an antecedent TIA within 24 h prior to ischemic stroke. The logistic regression model was developed to generate odds ratios (OR) to determine clinical factors that may increase the likelihood of exclusion or inclusion for thrombolytic therapy. The validity of the model was tested using a Hosmer-Lemeshow test, while the Receiver Operating Curve (ROC) was used to test the sensitivity of our model.

Results

In the recent-TIA ischemic stroke population, patients with a history of alcohol abuse (OR = 5.525, 95% CI, 1.003–30.434, p = 0.05), migraine (OR = 4.277, 95% CI, 1.095–16.703, p = 0.037), and increasing NIHSS score (OR = 1.156, 95% CI, 1.058–1.263, p = 0.001) were associated with the increasing odds of receiving rtPA, while older patients (OR = 0.965, 95% CI, 0.934–0.997, P = 0.033) were associated with the increasing odds of not receiving rtPA.

Conclusion

In recent-TIA ischemic stroke patients, older patients with higher INR values are associated with increasing odds of exclusion from thrombolytic therapy. Our findings demonstrate clinical risks factors that can be targeted to improve the use and eligibility for rtPA in in recent-TIA ischemic stroke patients.

A novel biscoumarin derivative dephosphorylates ERK and alleviates apoptosis induced by mitochondrial oxidative damage in ischemic stroke mice

AIM

We previously reported the protective effects of biscoumarin derivatives against oxidative stress, but effects of the derivative on mitochondrial oxidative damage induced apoptosis in ischemic stroke remains unknown.

METHODS

Primary neurons were subjected to oxygen and glucose deprivation (OGD) for the in vitro simulation of ischemic stroke, and an ischemic stroke model was established in mice by operation of middle cerebral artery occlusion (MCAO).

RESULTS

The results indicated that the nontoxic concentration range of biscoumarin derivative Comp. B in neurons was from 0 to 30 μg/ml and the optimal protective concentration was 20 μg/ml. Treatment with Comp. B increased the cell survival rate and alleviated mitochondrial oxidative damage and apoptosis in OGD-treated neurons. Comp. B reduced the ratio of Bax/Bcl-2, inhibited the phosphorylation of ERK, and thus alleviated apoptosis in OGD-treated neurons. Further research demonstrated that the dephosphorylation effect on ERK of Comp. B is a key factor in alleviating apoptosis in neurons induced by OGD injury. Furthermore, Comp. B reduced the infarct volume, improved neurobehavioural score, and alleviated morphological changes and brain apoptosis in MCAO mice.

CONCLUSION

The novel biscoumarin derivative Comp. B alleviates mitochondrial oxidative damage and apoptosis in ischemic stroke mice. These findings might provide new insights that will aid in elucidating the effect of biscoumarin derivative against cerebral ischemic reperfusion injury and support the new development of Comp. B as a potential treatment for ischemic stroke.

Thin Slices and Maximum Intensity Projection Reconstructions Increase Sensitivity to Hyperdense Middle Cerebral Artery Sign in Acute Ischemic Stroke

Introduction: Cranial nonenhanced CT (NECT) imaging in hyperacute ischemic stroke is rarely used for assessing arterial obstruction of middle cerebral artery by identifying hyperdense artery sign (HAS). Considering, however, its growing importance due to its impact on the decision-making process of thrombolysis with or without mechanical thrombectomy improved sensitivity to HAS is necessary, particularly in the group of less experienced clinicians being frequently the first one assessing the presence of HAS on NECT. Objective: The present study aimed to investigate the effect of different NECT image reconstructions on the correct detection of hyperdense middle cerebral artery sign in a cohort of observers with lower experience level on NECT. Particularly, MIP image reconstructions were expected to be useful for less experienced observers due to both strengthening of the hyperdensity of HAS and streamlining to less image slices. Methods: Twenty-five of 100 patients’ NECT image data presented with HAS. Sixteen observers with lower practice level on NECT (10 radiologists and 6 neurologists) evaluated independently the 3 image reconstructions of each data set with thin slice 1.5 mm, thick slab 5 mm, and 6-mm maximum intensity projection (MIP) and rated the presence of HAS in middle cerebral artery. A GEE model with random observer effect was used to examine the influence of the 3 image reconstructions on sensitivity to HAS. A linear mixed effects regression model was used to investigate the ranking of detectability of HAS. Interrater reliability was determined by Fleiss’ kappa coefficient (κ). Results: Recognition of HAS and sensitivity to HAS significantly differed between the 3 image reconstructions (p = 0.0106). MIP and thin slice reconstructions yielded each on average the highest sensitivities with 73% compared to thick slab reconstruction with 45% sensitivity. The interobserver reliability was fair (κ, 0.3–0.4). Detectability of HAS was significantly easier and better visible ranked on MIP and thin slice reconstructions compared to thick slab (p < 0.05). Conclusion: MIP and thin slice reconstructions increased the sensitivity to HAS (73%), whereas thick slab reconstructions seemed to be less appropriate (45%).

SIR HELMET (Safety In Radiology HEalthcare Localised Metrological EnviromenT): a low-cost negative-pressure isolation barrier for shielding MRI frontline workers from COVID-19 exposure

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Low cost reusable acrylic and silicone rubber barrier shield design.

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Localised negative pressure environment simulating isolation rooms.

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Does not affect MRI image quality even on the most sensitive sequences.

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Additional personal protective equipment for frontline healthcare professionals.

Prognostic value of cerebral infarction coefficient in patients with massive cerebral infarction

OBJECTIVE

We proposed the concept of the cerebral infarction coefficient, which is cerebral infarction volume/brain volume. This study aimed to evaluate the prognostic value of the cerebral infarction coefficient in patients with massive cerebral infarction (MCI).

METHODS

According to the modified Rankin score, 71 patients with acute MCI were divided into good prognosis and poor prognosis groups. Clinical and imaging data of the two groups were collected and univariate analysis was carried out. If there were significant differences in the data between the two groups, binary logistic regression analysis was performed.

RESULTS

The poor prognosis group had a significantly higher cerebral infarction volume, cerebral infarction coefficient, and D-dimer levels, older age, the highest body temperature, a higher rate of a history of atrial fibrillation, and a lower rate of a history of hypertension compared with the good prognosis group (all P < 0.05). Binary logistic regression analysis showed that the cerebral infarction coefficient was an independent risk factor for a poor prognosis of patients with MCI (P < 0.05, 95 % confidence interval, 2.091, 42.562), and the odds ratio was 8.506. The area under the receiver operating characteristic curve for the cerebral infarction coefficient was 0.753. When the cut-off value was 7.8 %, the sensitivity of predicting a poor prognosis of patients with MCI was 92.5 %.

CONCLUSION

The cerebral infarction coefficient may have predictive value in determining the prognosis of patients with MCI.

Contrast-Induced Acute Kidney Injury in Radiologic Management of Acute Ischemic Stroke in the Emergency Setting

BACKGROUND AND PURPOSE

The use of invasive cerebral angiography with CTA for active treatment of patients with suspected ischemic strokes has been increasing recently. This study aimed to identify the incidence of postcontrast acute kidney injury using baseline renal function when CTA and cerebral angiography were performed sequentially.

MATERIALS AND METHODS

This retrospective observational study evaluated adults (18 years of age or older) with ischemic stroke who underwent CTA and cerebral angiography sequentially between 2010 and 2018. The incidence of postcontrast acute kidney injury was determined using the baseline estimated glomerular filtration rate. The value of the baseline estimated glomerular filtration rate at which the occurrence of postcontrast acute kidney injury increased was also determined.

RESULTS

Postcontrast acute kidney injury occurred in 57/601 (9.5%) patients. Those with a baseline estimated glomerular filtration rate of <30 mL/min/1.73 m² showed a higher incidence of acute kidney injury. Age, chronic kidney disease, medication (nonsteroidal anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, β blockers, statins, and insulin) use following contrast media exposure, and serum albumin affected the incidence of postcontrast acute kidney injury. The incidence of postcontrast acute kidney injury increased when the baseline estimated glomerular filtration rate was <43 mL/min/1.73 m².

CONCLUSIONS

Patients with low baseline renal function had the highest incidence of postcontrast acute kidney injury after CTA and cerebral angiography, but no fatal adverse effects were documented. Thus, patients suspected of having a stroke should be actively managed with respect to neurovascular function.

Early seizures after ischemic stroke: focus on thrombolysis

INTRODUCTION

Stroke is a significant underlying cause of epilepsy. Seizures due to ischemic stroke (IS) are generally categorized into early seizures (ESs) and late seizures (LSs). Seizures in thrombolysis situations may raise the possibility of other etiology than IS.

AIM

We overtook a systematic review focusing on the pathogenesis, prevalence, risk factors, detection, management, and clinical outcome of ESs in IS and in stroke/thrombolysis situations. We also collected articles focusing on the association of recombinant tissue-type plasminogen activator (rt-PA) treatment and epileptic seizures.

RESULTS

We have identified 37 studies with 36,775 participants. ES rate was 3.8% overall in patients with IS with geographical differences. Cortical involvement, severe stroke, hemorrhagic transformation, age (<65 years), large lesion, and atrial fibrillation were the most important risk factors. Sixty-one percent of ESs were partial and 39% were general. Status epilepticus (SE) occurred in 16.3%. 73.6% had an onset within 24 h and 40% may present at the onset of stroke syndrome. Based on EEG findings seizure-like activity could be detected only in approximately 18% of ES patients. MRI diffusion-weighted imaging and multimodal brain imaging may help in the differentiation of ischemia vs. seizure. There are no specific recommendations with regard to the treatment of ES.

CONCLUSION

ESs are rare complications of acute stroke with substantial burden. A significant proportion can be presented at the onset of stroke requiring an extensive diagnostic workup.

Radiological Eye Deviation as a Predictor of Large Vessel Occlusion in Acute Ischaemic Stroke

BACKGROUND

Detection of large vessel occlusion (LVO) is required for endovascular therapy in acute ischemic stroke (AIS) but CT angiography (CTA) is not always performed at primary stroke centers. Eye deviation on CT brain has been associated with improved stroke detection, but comparisons with angiographic status have been limited. This study sought to determine if radiological eye deviation was associated with LVO.

METHODS

All AIS patients given intravenous thrombolysis who had acute CTA performed in 2 stroke units were reviewed over 2013-2015 for the presence of LVO. Eye deviation was determined by 2 clinicians blinded to LVO status. Logistic regression was performed to determine which factors predicated LVO.

RESULTS

Total 195 AIS patients with acute CTA were identified; 124 (64%) had LVO. Median age was 72 (IQR 64-82) years, median National Institutes of Health Stroke Scale (NIHSS) was 12 (IQR 7-14). LVO patients had a higher NIHSS (15 versus 7, p < .01) and were more likely to have eye deviation on CT brain (71% versus 22.5%, p < .01). Logistic regression confirmed NIHSS score and eye deviation were associated with LVO, with odds ratios of 1.15 (per point) and 5.13 respectively. NIHSS less than equal to 11 gave greatest sensitivity (78.5%) and specificity (76.1%) for LVO with a positive predictive value of 84.7%. Eye deviation was similar with sensitivity 71%, specificity 77.5%, and 84.6%.

CONCLUSIONS

Eye deviation on CT brain is strongly associated with LVO. Presence of eye deviation on CT should alert clinicians to probability of LVO and for formal angiographic testing if not already performed.

Imaging of Brain Infarctions: Beyond the Usual Territories

In this review, our intension is to present imaging features of several categories of uncommon cases of brain infarctions including infarctions associated with neurovascular variants, infarctions along small arterial territories, and brainstem stroke syndromes. Infarctions associated with neurovascular variants include azygos anterior cerebral artery territory infarction and artery of Percheron infarction. In the second group, we discuss anterior choroidal artery infarction and artery of Heubner infarction. The third group highlights brainstem stroke syndromes, including Claude and Benedikt syndromes due to midbrain infarction; Foville, Marie Foix, and locked-in syndromes due to pontine infarction; and Dejerine (medial medullary), bilateral medial medullary, and Wallenberg (lateral medullary) syndromes.

Role of Decompressive Craniectomy in Ischemic Stroke

Ischemic stroke is one of the leading causes for death and disability worldwide. In patients with large space-occupying infarction, the subsequent edema complicated by transtentorial herniation poses a lethal threat. Especially in patients with malignant middle cerebral artery infarction, brain swelling secondary to the vessel occlusion is associated with high mortality. By decompressive craniectomy, a significant proportion of the skull is surgically removed, allowing the ischemic tissue to shift through the surgical defect rather than to the unaffected regions of the brain, thus avoiding secondary damage due to increased intracranial pressure. Several studies have shown that decompressive craniectomy reduces the mortality rate in patients with malignant cerebral artery infarction. However, this is done for the cost of a higher proportion of patients who survive with severe disability. In this review, we will describe the clinical and radiological features of malignant middle cerebral artery infarction and the role of decompressive craniectomy and additional therapies in this condition. We will also discuss large cerebellar stroke and the possibilities of suboccipital craniectomy.

Mechanical thrombectomy in acute ischaemic stroke: a review of the different techniques

Endovascular mechanical thrombectomy (MT) is reserved for acute ischaemic stroke secondary to large vessel occlusion. The various MT techniques employed in the treatment of hyperacute strokes are constantly evolving with new devices and improvisation of existing technology (Wahlgren, et al 2016). In this review, we describe a variety of MT techniques gained from our experience of performing over 350 procedures in 7 years of providing a 24/7 service within the national framework of a hyperacute stroke centre. We outline a number of endovascular techniques, procedure limitations, and potential complications.

Metabolomics and Lipidomics of Ischemic Stroke

Ischemic stroke is a sudden loss of brain function due to the reduction of blood flow. Brain tissues cease to function with subsequent activation of the ischemic cascade. Metabolomics and lipidomics are modern disciplines that characterize the metabolites and lipid components of a biological system, respectively. Because the pathogenesis of ischemic stroke is heterogeneous and multifactorial, it is crucial to establish comprehensive metabolomic and lipidomic approaches to elucidate these alterations in this disease. Fortunately, metabolomic and lipidomic studies have the distinct advantages of identifying tissue/mechanism-specific biomarkers, predicting treatment and clinical outcome, and improving our understanding of the pathophysiologic basis of disease states. Therefore, recent applications of these analytical approaches in the early diagnosis of ischemic stroke were discussed. In addition, the emerging roles of metabolomics and lipidomics on ischemic stroke were summarized, in order to gain new insights into the mechanisms underlying ischemic stroke and in the search for novel metabolite biomarkers and their related pathways.

The Chinese Stroke Association scientific statement: intravenous thrombolysis in acute ischaemic stroke

The most effective medical treatment for acute ischaemic stroke (AIS) is to offer intravenous thrombolysis during the ultra-early period of time after the onset. Even based on the Consensus of Chinese Experts on Intravenous Thrombolysis for AIS in 2012 and 2014 Chinese Guidelines on the Diagnosis and Treatment of AIS, the rate of thrombolysis for AIS in China remained around 2.4%, and the rate of intravenous tissue plasminogen activator usage was only about 1.6% in real world. The indication of thrombolysis for AIS has been expanded, and contraindications have been reduced with recently published studies. In order to facilitate the standardisation of treating AIS, improve the rate of thrombolysis and benefit patients who had a stroke, Chinese Stroke Association has organised and developed this scientific statement.

Safety of Computed Tomographic Angiography in the Evaluation of Patients With Acute Stroke

Background and Purpose—

Noncontrasted head computed tomography (NCHCT) has long been the standard of care for acute stroke imaging. New guidelines recommending advanced vascular imaging to identify eligible patients for endovascular therapy have renewed safety concerns on the use of contrast in the emergent setting without laboratory confirmation of renal function.

Methods—

We compared computed tomographic angiography (CTA) versus NCHCT alone during acute stroke evaluation with focus on renal safety and timeliness of therapy delivery. We reviewed data on all emergency department patients for whom the Acute Stroke Intervention Team was activated between December 2013 and September 2014. Primary outcomes included acute kidney injury and change in serum creatinine from presentation to 24 to 48 hours (Δ serum creatinine [Cr]). We assessed therapy delay using door-to-CT and door-to-needle times.

Results—

Of 289 patients requiring Acute Stroke Intervention Team activation, 157 received CTA and 132 NCHCT only. There was no difference between groups in mean Cr at 24 to 48 hours (1.06 CTA; 1.40 NCHCT; P =0.059), ΔCr (−0.07 CTA, −0.11 NCHCT, P =0.489), or rates of acute kidney injury (5 CTA, 7 NCHCT, P =0.422). There was no significant difference in mean intravenous tissue plasminogen activator treatment times (68.11 minutes CTA, 81.36 minutes NCHCT; P =0.577). In the 157 patients who underwent CTA, 16 (10.2%) vascular anomalies and 55 (35.0%) high-grade stenoses or occlusions were identified.

Conclusions—

CTA acquisition during acute stroke evaluation was safe with regards to renal function and did not delay appropriate therapy delivery. Acute CTA acquisition offers additional clinical value in rapid identification of vascular abnormalities.

Cerebrovascular disease

With 16.9 million people who suffered a first-ever stroke in 2010 worldwide, stroke is a very common vascular disease. Epidemiologic studies have played an essential role in assessing this burden and in detecting the risk factors for stroke. Primary prevention of these risk factors, primarily hypertension, smoking, diabetes, and atrial fibrillation, has reduced the incidence in high-income countries. However, stroke remains a major cause of death and disability, and therefore research should be continued. Subarachnoid hemorrhages are less prevalent than strokes but have an even higher risk of death. Similar to stroke, epidemiologic studies identified smoking and hypertension as its most important risk factors, together with excessive alcohol intake. Although rare, arterial dissections, CADASIL, arteriovenous malformations, venous sinus thrombosis, moyamoya disease, and vasculitis can lead to serious symptoms. The burden and risk factors of those rare diseases are more challenging to assess. Whenever possible, they should be recognized in a timely manner for their increased risk of stroke, but most often they are diagnosed only at the time of stroke. Some cerebrovascular abnormalities do not result in immediate symptoms. This subclinical cerebrovascular disease includes silent infarcts, white-matter lesions, and microbleeds, and is incidentally found by neuroimaging. These lesions are not innocent, as several epidemiologic studies have associated subclinical cerebrovascular disease with an increased risk of stroke, cognitive decline, dementia, and death.

Sensitivity of Hyperdense Basilar Artery Sign on Non-Enhanced Computed Tomography

Purpose

The hyperdense basilar artery sign (HBAS) is an indicator of vessel occlusion on non contrast-enhanced computer tomography (NECT) in acute stroke patients. Since basilar artery occlusion (BAO) is associated with a high mortality and morbidity, its early detection is of great clinical value. We sought to analyze the influence of density measurement as well as a normalized ratio of Hounsfield unit/hematocrit (HU/Hct) ratio on the detection of BAO on NECT in patients with suspected BAO.

Materials and Methods

102 patients with clinically suspected BAO were examined with NECT followed immediately by Multidetector computed tomography Angiography. Two observers independently analyzed the images regarding the presence or absence of HBAS on NECT and performed HU measurements in the basilar artery. Receiver operating characteristic curve analysis was performed to determine the optimal density threshold for BAO using attenuation measurements or HU/Hct ratio.

Results

Sensitivity of visual detection of the HBAS on NECT was relatively low 81% (95%-CI, 54–95%) while specificity was high 91% (95%-CI, 82–96%). The highest sensitivity was achieved by the combination of visual assessment and additional quantitative attenuation measurements applying a cut-off value of 46.5 HU with 94% sensitivity and 81% specificity for BAO. A HU/Hct ratio >1.32 revealed sensitivity of 88% (95%-CI, 60–98%) and specificity of 84% (95%-CI, 74–90%).

Conclusion

In patients with clinically suspected acute BAO the combination of visual assessment and additional attenuation measurement with a cut-off value of 46.5 HU is a reliable approach with high sensitivity in the detection of BAO on NECT.

Imaging Patterns and Management Algorithms in Acute Stroke: An Update for the Emergency Radiologist

Neuroimaging plays a key role in the initial work-up of patients with symptoms of acute stroke. Understanding the advantages and limitations of available CT and MR imaging techniques and how to use them optimally in the emergency setting is crucial for accurately making the diagnosis of acute stroke and for rapidly determining appropriate treatment.

Sensitivity and specificity of the hyperdense artery sign for arterial obstruction in acute ischemic stroke

BACKGROUND AND PURPOSE

In acute ischemic stroke, the hyperdense artery sign (HAS) on noncontrast computed tomography (CT) is thought to represent intraluminal thrombus and, therefore, is a surrogate of arterial obstruction. We sought to assess the accuracy of HAS as a marker of arterial obstruction by thrombus.

METHODS

The Third International Stroke Trial (IST-3) was a randomized controlled trial testing the use of intravenous thrombolysis for acute ischemic stroke in patients who did not clearly meet the prevailing license criteria. Some participating IST-3 centers routinely performed CT or MR angiography at baseline. One reader assessed all relevant scans independently, blinded to all other data; we checked observer reliability. We combined IST-3 data with a systematic review and meta-analysis of all studies that assessed the accuracy of HAS using angiography (any modality).

RESULTS

IST-3 had 273 patients with baseline CT or MR angiography and was the largest study of HAS accuracy. The meta-analysis (n=902+273=1175, including IST-3) found sensitivity and specificity of HAS for arterial obstruction on angiography to be 52% and 95%, respectively. HAS was more commonly identified in proximal than distal arteries (47% versus 37%; P=0.015), and its sensitivity increased with thinner CT slices (r=-0.73; P=0.001). Neither extent of obstruction nor time after stroke influenced HAS accuracy.

CONCLUSIONS

When present in acute ischemic stroke, HAS indicates a high likelihood of arterial obstruction, but its absence indicates only a 50/50 chance of normal arterial patency. Thin-slice CT improves sensitivity of HAS detection.

CLINICAL TRIAL REGISTRATION URL

http://www.controlled-trials.com/ISRCTN25765518. Unique identifier: ISRCTN25765518.