Assessment Of Acute Ischemic Stroke Research Articles

Short-Term Outcome Assessment of Acute Ischemic Stroke After Intravenous Fibrinolytic Therapy: A Cross-sectional Study

Background: The disease burden of acute ischemic stroke (AIS) is an important health issue in today’s patient care. Urgent intravenous thrombolytic (UIT) therapy is one of the most popular treatments in these cases. Objectives: This study aimed to evaluate the 1-month outcome of patients with AIS who received urgent intravenous fibrinolytic therapy. Methods: In a prospective cross-sectional study, we evaluated the 1-month outcome of cases with a confirmed diagnosis of AIS who had received UIT therapy at the emergency department. Demographic data, mortality and morbidity, hospital length of stay, admission functional disability by Modified Rankin Scale (MRS), National Institutes of Health Stroke Scale (NIHSS), and final disposition of patients were all evaluated and recorded via their medical records or structured telephone inquiries. We compared all variables between the 2 groups (i.e., survived and expired groups). Results: Among 490 cases we assessed, age had a mean ± SD of 69.41 ± 12.25 years, and most cases were males (74.3%). The 1-month mortality rate in our sample was 4.08% (20 cases). The mean ± SD of hospital length of stay was 6.84 ± 7.32 days, with no significant difference between the 2 groups (P = 0.869). Demographic data showed no significant differences between the 2 groups. NIHSS and MRS scores were significantly higher in the expired group than in the survived group (P = 0.005 and P = 0.001, respectively). Conclusions: NIHSS and MRS scores were significantly higher in the expired cases. The 1-month mortality rate in this study was 4.08%.

Early assessment of acute ischemic stroke in rabbits based on multi-parameter near-field coupling sensing

BackgroundEarly diagnosis and continuous monitoring are the key to emergency treatment and intensive care of patients with acute ischemic stroke (AIS). Nevertheless, there has not been a fully accepted method targeting continuous assessment of AIS in clinical.MethodsNear-field coupling (NFC) sensing can obtain the conductivity related to the volume of intracranial components with advantages of non-invasiveness, strong penetrability and real-time monitoring. In this work, we built a multi-parameter monitoring system that is able to measure changes of phase and amplitude in the process of electromagnetic wave (EW) reflection and transmission. For investigating its feasibility in AIS detection, 16 rabbits were chosen to establish AIS models by bilateral common carotid artery ligation and then were enrolled for monitoring experiments.ResultsDuring the 6 h after AIS, the reflection amplitude (RA) shows a decline trend with a range of 0.69 dB and reflection phase (RP) has an increased variation of 6.48° . Meanwhile, transmission amplitude (TA) and transmission phase (TP) decrease 2.14 dB and 24.29° , respectively. The statistical analysis illustrates that before ligation, 3 h after ligation and 6 h after ligation can be effectively distinguished by the four parameters individually. When all those parameters are regarded as recognition features in back propagation (BP) network, the classification accuracy of the three different periods reaches almost 100%.ConclusionThese results prove the feasibility of multi-parameter NFC sensing to assess AIS, which is promised to become an outstanding point-of-care testing method in the future.

Rapid Assessment of Acute Ischemic Stroke by Computed Tomography Using Deep Convolutional Neural Networks.

Acute stroke is one of the leading causes of disability and death worldwide. Regarding clinical diagnoses, a rapid and accurate procedure is necessary for patients suffering from acute stroke. This study proposes an automatic identification scheme for acute ischemic stroke using deep convolutional neural networks (DCNNs) based on non-contrast computed tomographic (NCCT) images. Our image database for the classification model was composed of 1254 grayscale NCCT images from 96 patients (573 images) with acute ischemic stroke and 121 normal controls (681 images). According to the consensus of critical stroke findings by two neuroradiologists, a gold standard was established and used to train the proposed DCNN using machine-generated image features. Including the earliest DCNN, AlexNet, the popular Inception-v3, and ResNet-101 were proposed. To train the limited data size, transfer learning with ImageNet parameters was also used. The established models were evaluated by tenfold cross-validation and tested on an independent dataset containing 50 patients with acute ischemic stroke (108 images) and 58 normal controls (117 images) from another institution. AlexNet without pretrained parameters achieved an accuracy of 97.12%, a sensitivity of 98.11%, a specificity of 96.08%, and an area under the receiver operating characteristic curve (AUC) of 0.9927. Using transfer learning, transferred AlexNet, transferred Inception-v3, and transferred ResNet-101 achieved accuracies between 90.49 and 95.49%. Tested with a dataset from another institution, AlexNet showed an accuracy of 60.89%, a sensitivity of 18.52%, and a specificity of 100%. Transferred AlexNet, Inception-v3, and ResNet-101 achieved accuracies of 81.77%, 85.78%, and 80.89%, respectively. The proposed DCNN architecture as a computer-aided diagnosis system showed that training from scratch can generate a customized model for a specific scanner, and transfer learning can generate a more generalized model to provide diagnostic suggestions of acute ischemic stroke to radiologists.

Novel flat-panel cone-beam CT compared to multi-detector CT for assessment of acute ischemic stroke: A prospective study

PurposeCone beam CT (CBCT) imaging assessment of acute ischemic stroke (AIS) patients with large-vessel occlusion (LVO) in the angiosuite may improve stroke workflow and decrease time to recanalization. In order for this workflow to gain widespread acceptance, current CBCT imaging needs further development to improve image quality. Our study aimed to compare the image quality of a new CBCT protocol performed directly in the angiosuite with imaging from multidetector CT as a gold standard. MethodsAIS patients with an LVO who were candidates for endovascular treatment were prospectively included in this study. Following conventional multidetector CT (MDCT), patients underwent unenhanced cone beam CT (XperCT, Philips) imaging in the angiosuite, using two different protocols: a standard 20.8 s XperCT and/or an improved 10.4 s XperCT protocol. Images were evaluated using both qualitative and quantitative methods. ResultsWe included 65 patients in the study. Patients received CBCT imaging prior to endovascular treatment; 18 patients were assessed with a standard 20.8 s protocol scans and 47 with a newer 10.4 s scan. The quantitative analysis showed that the mean contrast-to-noise ratio (CNR) was significantly higher for the newer 10.4 s protocol compared with the 20.8 s protocol (2.08 +/- 0.64 vs. 1.15 +/- 0.27, p < 0.004) and the mean image noise was significantly lower for the 10.4 s XperCTs when compared with the 20.8 s XperCTs (6.30 +/- 1.34 vs. 7.82 +/- 2.03, p=<0.003). Qualitative analysis, including 6 measures of image quality, demonstrated that 74.1 % of the 10.4 s XperCT scans were ranked as ‘Acceptable’ for assessing parenchymal imaging in AIS patients(scoring 3–5 points on a 5-point Likert-scale), compared with 32.4 % of the standard 20.8 s XperCT and 100 % of the MDCT scans. Compared to the MDCT studies, 83 % of the 10.4 s XperCT scans were deemed sufficient image quality for a direct-to-angiosuite selection, compared to only 11 % for the standard 20.8 s scans. The largest image quality improvements included grey/white matter differentiation (59 % improvement), and reduction of image noise and artefacts (63 % & 50 % improvement, respectively). ConclusionsContinued advances in cone-beam CT allow marked improvements in image quality for the assessment of brain parenchyma, which supports a direct-to-angiosuite approach for AIS patients eligible for thrombectomy treatment.

Susceptibility weighted imaging in acute cerebral ischemia: review of emerging technical concepts and clinical applications.

Susceptibility weighted imaging (SWI) is an essential magnetic resonance imaging sequence in the assessment of acute ischemic stroke. In this article, we discuss the physics principals and clinical application of conventional SWI and multi-echo SWI sequences. We review the research evidence and practical approach of SWI in acute ischemic stroke by focusing on the detection and characterization of thromboembolism in the cerebral circulation. In addition, we discuss the role of SWI in the assessment of neuroparenchyma by depiction of asymmetric hypointense cortical veins in the ischemic territory (surrogate tissue perfusion), detection of existing microbleeds before stroke treatment and monitoring for hemorrhagic transformation post-treatment. In conclusion, the SWI sequence complements other parameters in the stroke magnetic resonance imaging protocol and understanding of the research evidence is vital for practising stroke neurologists and neuroradiologists.

Abstract WP57: Utility of Flat Panel CT Perfusion for Physiologic Assessment of Acute Ischemic Stroke in the Angiography Suite

Introduction The decision to perform endovascular intervention in patients with acute ischemic stroke (AIS) may be guided by physiologic imaging such as CT perfusion (CTP) demonstrating a salvageable penumbra, but such studies can delay transfer to the angiography suite. Flat Panel Detector CT (FPD-CT) allows pre, intra and post-procedural physiologic assessment using rotational images acquired on the angiography table; however these measurements have not been correlated with conventional perfusion techniques. We began a prospective, observational comparison of standard, multi-slice CTP with FPD-CT perfusion for AIS interventions, and report our initial results. Methods Patients with AIS that are candidates for endovascular intervention and have standard CTP images available were enrolled in the study after obtaining informed consent and following the IRB approved protocol. FPD-CTP images were obtained with aortic contrast injection and commercially available workstation image assessment (Siemens, Erlangen, Germany) before and after intervention, and compared with standard CT perfusion and follow up images. Results A total of 3 cases have been enrolled. All demonstrated anatomic correlations between perfusion defects in the standard CTP and the FPD-CTP. Case example: A 58 year old man developed left sided hemiplegia and standard CTP demonstrated a right MCA defect with a small core infarction (Fig 1 A). Pre-intervention FPD-CTP showed the same defect pattern (Fig 1 B), and successful mechanical thrombectomy was performed (Fig 1 C,D). Post-intervention FPD-CT showed reversal of perfusion defect outside the core infarct (Fig 1 E). The patient had good clinical recovery and only small infarct on follow up CT (Fig 1 F). Conclusions Early experience with FPD-CTP imaging shows correlation with standard CTP images and reversal of perfusion defect following successful recanalization, suggesting it may be a valuable aid for decision making in AIS intervention.

Automated Decision-Support System for Prediction of Treatment Responders in Acute Ischemic Stroke

MRI is widely used in the assessment of acute ischemic stroke. In particular, it identifies the mismatch between hypoperfused and the permanently damaged tissue, the PWI-DWI mismatch volume. It is used to help triage patients into active or supportive treatment pathways. COMBAT Stroke is an automated software tool for estimating the mismatch volume and ratio based on MRI. Herein, we validate the decision made by the software with actual clinical decision rendered. Furthermore, we evaluate the association between treatment decisions (both automated and actual) and outcomes. COMBAT Stroke was used to determine PWI-DWI mismatch volume and ratio in 228 patients from two European multi-center stroke databases. We performed confusion matrix analysis to summarize the agreement between the automated selection and the clinical decision. Finally, we evaluated the clinical and imaging outcomes of the patients in the four entries of the confusion matrix (true positive, true negative, false negative, and false positive). About 186 of 228 patients with acute stroke underwent thrombolytic treatment, with the remaining 42 receiving supportive treatment only. Selection based on radiographic criteria using COMBAT Stroke classified 142 patients as potential candidates for thrombolytic treatment and 86 for supportive treatment; 60% sensitivity and 29% specificity. The patients deemed eligible for thrombolytic treatment by COMBAT Stroke demonstrated significantly higher rates of compromised tissue salvage, less neurological deficit, and were more likely to experience thrombus dissolving and reestablishment of normal blood flow at 24 h follow-up compared to those who were treated without substantial PWI-DWI mismatch. These results provide evidence that COMBAT Stroke, in addition to clinical assessment, may offer an optimal framework for a fast, efficient, and standardized clinical support tool to select patients for thrombolysis in acute ischemic stroke.

Review of a Ph.D. thesis entitled ′A study of the assessment of acute ischemic stroke by the use of optimized diffusion-weighted MR imaging′

Review of a Ph.D. thesis entitled ′A study of the assessment of acute ischemic stroke by the use of optimized diffusion-weighted MR imaging′

Could Platelet Aggregation Ratio Be an Indicator for Differential Diagnosis of Transient Ischemic Attack and Cerebral Ischemic Stroke?

Background: Platelet aggregation plays an important role in the pathogenesis of thromboembolic cerebrovascular disease. Platelet aggregation ratio (PAR) and its derivates have been used successfully to identify the effectiveness of antiplatelet agents and their optimum dosage in patients suffering from stroke. However, we failed to find any study using PAR as a predictive factor in differential diagnosis of ischemic cerebrovascular diseases. In this study, we aimed to investigate PAR in patients with acute ischemic stroke and transient ischemic attack (TIA), comparing their neuroradiological features, and whether PAR values could be an indicator for differential diagnosis of TIA and cerebral ischemic stroke. Methods: The study consisted of 75 adult patients who were admitted with suspected stroke and 25 control healthy individuals. All patients were diagnosed with acute ischemic stroke or TIA and the diagnoses were confirmed by clinical examination and computed tomography (CT). The stroke group consisted of 45, and the TIA group of 30 consecutive patients. The patients included in this study had noncardioembolic stroke. PAR values were measured on admission in all groups, according to the modified method of Wu and Hoak. The statistical significance of differences was evaluated using one-way ANOVA, the unpaired Student t test and the Bonferroni and Tamhane post hoc tests.Results:Differences in PARs between the control and TIA groups, control and stroke groups and stroke and TIA groups were significant (p < 0.001). Nevertheless, in each group, differences between genders were not statistically significant. Initial CT scan demonstrated early infarction sign in 26 stroke patients (57%); however, in 19 stroke patients, it was not detected. Differences in PARs between TIA and stroke patients, whose initial CT scan findings were negative, were found to be significant. However, differences in PARs between CT negative stroke patients and positive stroke patients were not significant. Conclusion: We believe that the use of PAR values in the assessment of acute ischemic stroke and TIA could open up a new perspective in the management of such patients. In differential diagnosis, PAR values have to combine with neurological examination and CT scan signs. The current test is not able to differentiate vascular occlusive diseases in other organs from vascular occlusive problems in the brain. Further study is needed to determine the sensitivity and specificity of this test in all patients and to confirm the prognostic value in stroke patients.

Evaluation of ischemic tissue reversibility by SPECT or DWI/PWI MRI

The potential for application of SPECT and diffusion/perfusion MRI study warrants further evaluation as it may help to improve the assessment of acute ischemic stroke and to choose the most appropriate therapeutic strategy. Since the penumbra is a hypoperfused but viable tissue, it represents an ideal therapeutic target of acute ischemic stroke. The ischemic penumbra is able to regain its function if promptly reperfused. SPECT and diffusion/perfusion MRI have the advantage of giving semiquantitative estimate of CBF as well as various ischemic thresholds. Although the hypoperfused area visualized by SPECT imaging shows not only the ischemic core (irreversible tissue) but also the penumbra (reversible tissue), we are able to know the different CBF thresholds such as penumbra, infarction and hemorrhage. Therefore, SPECT and diffusion/perfusion MRI can provide important information to allow the most appropriate candidate for the thrombolytic therapy and neurointerventional treatment to be selected.

Simultaneous multi-section perfusion CT and CT angiography for the assessment of acute ischemic stroke

Introduction of helical computed tomography (CT) scanning has enabled rapid imaging of the vascular status by means of CT angiography and perfusion CT. By virtue of recent multi-detector technology, helical CT has the ability to perform both CT angiography and multi-section perfusion CT simultaneously. This study investigated the clinical feasibility of simultaneous assessment of perfusion CT and CT angiography in patients with acute ischemic stroke. Perfusion CT and CT angiography were performed simultaneously in a series of consecutive 31 acute ischemic stroke patients. The time required for the entire processing was about 15 minutes. Contrast agent was used in a total dose of 100 ml (35 ml for perfusion CT and 65 ml for CT angiography). Simultaneous perfusion CT scans and CT angiographies were of diagnostic quality for 29 patients (94%). In large territorial infarct patients, perfusion CT could predict all perfusion deficits of the final lesions (10 out of 10 lesions) and CT angiography could detect 9 of 10 occlusions of major cerebral arteries (90%). In patients with small lacunar or subcortical infarcts, perfusion CT could predict 9 out of 19 lesions (47.4%), and false-negative were encountered in small lesions (three patients) or in inadequate coverage of data acquisition (seven patients). Acute stage thrombolytic intervention could be carried out based on the findings, and the success of thrombolytic therapy could be demonstrated by follow-up study. Simultaneous perfusion CT and CT angiography is the very useful tool for the rapid and adequate diagnosis of almost all of the large territorial infarcts and some of non-territorial lacunar infarcts. It is an easy-to-perform and safe imaging technique to assess acute ischemic stroke.

Effect of b value on contrast during diffusion-weighted magnetic resonance imaging assessment of acute ischemic stroke.

To examine the effect of varying the diffusion encoding strength (b value) on the contrast (signal difference, Delta S) between damaged and normal tissue during diffusion-weighted magnetic resonance imaging (DWI) assessment of acute ischemic stroke. Phantoms with diffusion values approximating those expected in acutely infarcted and normal tissue were constructed from a mixture of agar and formaldehyde and imaged at varying b values (0-3000 mm(-2) second). Ten patients were imaged with multiple b values (500-2500 mm(-2) second) within 12 hours of stroke onset. Theoretical calculations showed that for any combination of diffusion coefficients there existed an optimal b value that was higher than the standard setting of 1000 mm(-2) second, and this was confirmed by the phantom studies. In the patients, increasing b from 1000 to 1500 mm(-2) second increased Delta S (average, 22.4%; P = 0.001), but no consistent benefit was seen at b = 2000 mm(-2) second (P = 0.408). This compared favorably with the average optimal b value of 1662 mm(- 2) second calculated from the patients. These results suggest that increasing the b value from 1000 to 1500 mm(-2) second would increase contrast between infarcted and normal tissue in the setting of acute ischemic stroke.