Decision Criteria for Large Vessel Occlusion Using Transcranial Doppler Waveform Morphology

Purpose: To validate a Machine Learning algorithm able to identify LVO on NCCT. Methods: Patients with suspected acute stroke who underwent NCCT+CT Angiography (CTA) from two comprehensive stroke centers were included. Patients with intracranial haemorrhage were excluded. Two experienced radiologists identified the presence of LVO on CTA (NR-CTA) tagging the clot location and manually segmenting the clot. Acute ischemia and clot signs on NCCT were also depicted with assistance of the CTA clot location. With this information a deep learning system was used to create an algorithm (Deepstroke) to identify and locate the presence/absence of acute ischaemia and clot signs in NCCT. Deepstroke image output was used to train a binary classifier to determine LVO on NCCT. Cross-validation was performed in a stratified 5-fold of the data, including deep learning training. We also studied the effect on Deepstroke accuracy when adding the patients NIHSS and time from onset to the model (Deepstroke+). Results: The data cohort included 1354 patients, 724 (53%) with LVO by NR-CTA. The accuracy of Deepstroke to identify LVO had an AUC of 0.81 (sensitivity 0.85; specificity 0.49, PPV 0.66, NPV 0.74), and improved combined with NIHSS and time from symptom onset to AUC 0.88 (sensitivity 0.87, specificity 0.68, PPV 0.76, NPV 0.82). Deepstroke performed better on larger occlusions (Table). Among patients identified as LVO by Deepstroke+ only 19% showed no findings on NR-CTA. The agreement in LVO detection between NR-CTA and Deepstroke+ was 0.78 (Deepstroke was 0.68). Process time per patient was below 120s. Conclusions: In patients with suspected acute stroke, Deepstroke identified LVO in NCCT with a high correlation with radiologist readings of CTAs. Deepstroke could reduce the need to perform CTA, generate alarms and increase the efficiency of patients transfers in the acute management in stroke networks. Deepstroke accuracy will improve as more cases are added to the training set.

Aims The Hunter-8 and the ACT-FAST are stroke scales used in Australia for the pre-hospital identification of large vessel occlusion (LVO) stroke but have not previously been compared. Moreover, their use in identifying distal arterial occlusions has not previously been assessed. We therefore aimed to describe the area under the receiver operating curve (AUC) of the Hunter-8 versus the ACT-FAST for the detection of classic LVO. Methods Both scales were performed on consecutive patients presenting with stroke-like symptoms within 24 hours of symptom onset presenting to the emergency department at a tertiary referral hospital between June 2018 and January 2019. The AUC of the Hunter-8 and the ACT-FAST was calculated for the detection of LVO using different definitions [classic LVO (proximal segment of the middle cerebral artery (MCA-M1), terminal internal carotid artery (T-ICA), or tandem occlusions) and extended LVO (classic LVO plus proximal MCA-M2 and basilar occlusions)]. Results Of 126 suspected stroke patients, there were 24 classic LVO and 34 extended LVO. For detection of classic LVO, the Hunter-8 had an AUC of 0.79 and the ACT-FAST had an AUC of 0.77. For extended LVO, the AUC was 0.71 and 0.70 respectively. Conclusion Both scales represent a significant opportunity to identify patients with proven potential benefit from thrombectomy (classic LVO), however M2 and basilar occlusions may be more challenging to identify with these scales.

IntroAccurate identification of large vessel occlusion (LVO) strokes in the field may save lives through reduced transport times. Emergency Medical Services (EMS) training is critical to the successful implementation of...

Several new techniques have emerged for detecting anterior circulation large vessel occlusion by quantifying relative vessel density including RAPID-CTA, potentially allowing for faster triage and decreased time to mechanical thrombectomy. We present our one-year experience on positive predictive value of RAPID-CTA for the detection of large vessel occlusion in patients presenting with stroke symptoms and its effect on treatment time and clinical outcomes. Three hundred and ten patients presenting with stroke symptoms with relative vessel density <60% on RAPID-CTA were included (average age 70 years, 145 male, 165 female). Examinations were considered positive if there was evidence of large vessel occlusion or high grade stenosis. Computed tomography angiography to groin puncture time was calculated during one-year time intervals before and after RAPID-CTA installation. Ninety-day Modified Rankin Scale scores were obtained for patients in each cohort. Of the 310 patients, 270 had large vessel occlusion or high grade stenosis (87% positive predictive value), with 161 having large vessel occlusion. Using 45% relative vessel density threshold, 129/161 large vessel occlusion were detected (80% sensitivity) and 163/172 examinations were positive (95% positive predictive value). Computed tomography angiography to groin puncture time was significantly lower after deployment of RAPID-CTA (93 min vs 68 min, p<0.05). Average 90 day modified Rankin Scale score was lower in the RAPID-CTA group with a higher percentage of patients with functional independence, although the data was not statistically significant. RAPID-CTA had high positive predictive value for large vessel occlusion with a 45% relative vessel density threshold, which could facilitate active worklist reprioritization. Time to treatment was significantly lower and clinical outcomes were improved after deployment of RAPID-CTA.

Objective The Hunter-8 prehospital stroke scale predicts large vessel occlusion in hyperacute ischemic stroke patients (LVO) at hospital admission. We wished to test its performance in the hands of paramedics as part of a prehospital triage algorithm. We aimed to determine (a) the proportion of patients identified by the Hunter-8 algorithm, receiving reperfusion therapies, (b) whether a call to stroke team improved this, and (c) performance for LVO detection using an expanded LVO definition. Methods A prehospital workflow combining pre-morbid functional status, time from symptom onset, and the Hunter-8 scale was implemented from July 2019. A telephone call to the stroke team was prompted for potential treatment candidates. Classic LVO was defined as a proximal middle cerebral artery (MCA-M1), terminal internal carotid artery, or tandem occlusion. Extended LVO added proximal MCA-M2 and basilar occlusions. Results From July 2019 to April 2021, there were 363 Hunter-8 activations, 320 analyzed: 181 (56.6%) had confirmed ischemic strokes, 13 (4.1%) transient ischemic attack, 91 (28.5%) stroke mimics, and 35 (10.9%) intracranial hemorrhage. Fifty-two patients (16.3%) received reperfusion therapies, 35 with Hunter-8 ≥ 8. The stroke doctor changed the final destination for 76 patients (23.7%), and five received reperfusion therapies. The AUCs for classic and extended LVO were 0.73 (95% CI 0.66–0.79) and 0.72 (95% CI 0.65–0.77), respectively. Conclusion The Hunter-8 workflow resulted in 28.7% of confirmed ischemic stroke patients receiving reperfusion therapies, with no secondary transfers to the comprehensive stroke center. The role of communication with stroke team needs to be further explored.

IntroductionPre-hospital identification of large vessel occlusions (AIS-LVO) has proven to be successful in interhospital transfers and triaging.Aim of StudyThis study compares 8 stroke screening scales to detect anterior and posterior...

The identification of large vessel occlusion with underlying intracranial atherosclerotic disease (ICAS-LVO) before endovascular treatment (EVT) continues to be a challenge. We aimed to analyze baseline clinical-radiological features associated with ICAS-LVO that could lead to a prompt identification. We performed a retrospective cross-sectional study of consecutive patients with stroke treated with EVT from January 2020 to April 2022. We included anterior LVO involving intracranial internal carotid artery and middle cerebral artery. We analyzed baseline clinical and radiological variables associated with ICAS-LVO and evaluated the diagnostic value of a multivariate logistic regression model to identify ICAS-LVO before EVT. ICAS-LVO was defined as presence of angiographic residual stenosis or a trend to re-occlusion during EVT procedure. A total of 338 patients were included in the study. Of them, 28 patients (8.3%) presented with ICAS-LVO. After adjusting for confounders, absence of atrial fibrillation (OR 9.33, 95% CI 1.11–78.42; p = 0.040), lower hypoperfusion intensity ratio (HIR [Tmax > 10 s/Tmax > 6 s ratio], (OR 0.69, 95% CI 0.50–0.95; p = 0.025), symptomatic intracranial artery calcification (IAC, OR .15, 95% CI 1.64–26.42, p = 0.006), a more proximal occlusion (ICA, MCA-M1: OR 4.00, 95% CI 1.23–13.03; p = 0.021), and smoking (OR 2.91, 95% CI 1.08–7.90; p = 0.035) were associated with ICAS-LVO. The clinico-radiological model showed an overall well capability to identify ICAS-LVO (AUC = 0.88, 95% CI 0.83–0.94; p < 0.001). In conclusion, a combination of clinical and radiological features available before EVT can help to identify an ICAS-LVO. This approach could be useful to perform a rapid assessment of underlying etiology and suggest specific pathophysiology-based measures. Prospective studies are needed to validate these findings in other populations.

Background and Purpose: Rapid detection of large vessel occlusion (LVO) is essential for rapid triage for thrombectomy to salvage at-risk tissue. Early detection of LVO on noncontrast CT head (NCCT) could facilitate triage before advanced imaging is obtained. RAPID hyperdense vessel sign (HVS), a new fully automated software- tool for HVS detection is compared to experienced radiologists, for early LVO detection on NCCT, and validated with CTA. Methods: Scans were selected from a database of 335 scans, of which 166 were selected by stratified random selection. Images were evaluated by the Rapid automated software, and six readers, two radiologists, and four neuroradiologists. The Rapid algorithm returns a score between zero and one, and a threshold of 0.5 was applied of HVS. Radiologists read each scan twice, 30 days apart. A scan rating confidence scale was used, from “very confident of absence,” to “very confident of HVS,” and a separate “technically inadequate” rating, and this was compared to the Rapid HVS score. “Very Confident,” or “Confident” rated scans were considered HVS positive. Results: Demographics: 54% were men. Ages ranged 23 - 94 with a median of 65. GE, Philips, Siemens, and Toshiba scanners are represented. Agreement with RAPID for HVS detection was 75% to 84%. Below a HVS score of 0.4 the proportion of LVO positive scans was 46% (indeterminate), between 0.4 and 0.6 the proportion was 62.5% (probable), and above 0.6 the proportion was 90% (likely). The scan rating confidence grade correlated with the Rapid HVS score. The software identified 53% of the LVOs, comparable to human readers (26-57%) A clinical practice simulation of RAPID followed by a reader identified 61.3% (p=0.02 vs readers alone). Among the 61 patients with no LVO on CTA, readers had a false positive rate of less than 7% as compared to 15% for the software. Median software processing time was 54 seconds. Conclusions: Expert readers, and the Rapid software, detect an HVS in about 50% of CT head images with LVO on CTA. When Rapid software is used in tandem with an experienced reader, HVS can be detected in up to two thirds of patients with LVO on CTA. This high percentage of early LVO detection would facilitate faster triage of patients for more advanced imaging and/or therapeutic interventions.

Background: The Colorado Stroke Advisory Board (COSAB) asked three Joint Commission (JC) comprehensive stroke centers (CSC) and one primary stroke center (PSC) to assist with determining the usefulness of the Cincinnati Pre-Hospital Stroke Severity Score (CPSSS) in predicting large vessel occlusion (LVO) in patients with acute stroke symptoms. Purpose: The purpose of the study was to determine the real world applicability of the CPSSS in predicting LVO. Methods: CPSSS and LVO data was collected by stroke coordinators at three CSCs and one PSC for all patients brought to their respective emergency departments via local emergency medical services (EMS) from June 2016 to July 2016 as stroke alerts. The CPSSS was calculated retrospectively using the initial documented neurological exam and LVO was determined by initial computed tomography (CT) imaging results or physician notes in the electronic medical record. Results: Our study included 235 patients that were brought to 4 certified stroke centers in the Denver metropolitan area during a two month period in 2016. Eighty percent of patients (N=187/235) correctly screened negative on the CPSSS. Ten percent (N=23/235) of patients screened positive and were later determined to have LVO based on initial imaging. Four patients went on for endovascular treatment at a CSC that initially screened negative using the CPSSS. Nine percent (N=21/235) of patients screened false-positive for LVO. Top reasons for false positive CPSSS include intracerebral hemorrhage, altered mental status, seizure, and brain stem stroke. Conclusion: CPSSS is a reasonable screening tool to assess for LVO. More study is recommended to determine how to avoid missing LVO in stroke patients with mild symptoms on initial presentation.

A reliable and fast instrument for prehospital detection of large vessel occlusion (LVO) stroke would be a game-changer in stroke care, because it would enable direct transportation of LVO stroke patients to the nearest comprehensive stroke center for endovascular treatment. This strategy would substantially improve treatment times and thus clinical outcomes of patients. Here, we outline our view on the requirements of an effective prehospital LVO detection method, namely: high diagnostic accuracy; fast application and interpretation; user-friendliness; compactness; and low costs. We argue that existing methods for prehospital LVO detection, including clinical scales, mobile stroke units and transcranial Doppler, do not fulfill all criteria, hindering broad implementation of these methods. Instead, electroencephalography may be suitable for prehospital LVO detection since in-hospital studies have shown that quantification of hypoxia-induced changes in the electroencephalography signal have good diagnostic accuracy for LVO stroke. Although performing electroencephalography measurements in the prehospital setting comes with challenges, solutions for fast and simple application of this method are available. Currently, the feasibility and diagnostic accuracy of electroencephalography in the prehospital setting are being investigated in clinical trials.

IntroductionThe efficacy of both intravenous treatment (IVT) and endovascular treatment (EVT) for patients with acute ischaemic stroke strongly declines over time. Only a subset of patients with ischaemic stroke caused...

Background and purpose: Modern stroke treatment has been revolutionized by image-guided selection of patients for endovascular thrombectomy. Current automated platforms allow for real-time identification of large vessel occlusion and salvageable brain tissue. We had previously demonstrated that a “CTA for all” policy for stroke patients immediately upon arrival assists in the earlier identification of treatment candidates. We now sought to evaluate the performance of these platforms under this policy. Methods: All patients that presented to Henry Ford Health System hospitals over a period of 6 weeks received CTA of the head and neck upon initial presentation. The images were processed with two automated software platforms. We prospectively collected processing times, large-vessel-occlusion alerts, performance warnings, and LVO density ratios. We compared these with the interpretations of board-certified radiologists, and analyzed the performance of each platform. Results: 276 patients presented with stroke symptoms and received CT angiography upon presentation. Both platforms were able to image all stroke patients within their FDA-approved indications. Both platforms were noted to have comparable sensitivity, specificity, PPV and NPV, and excellent accuracy. The overall prevalence of LVO was extremely low (8/276). As a result, for both, NPV was much better than PPV because of the percentage of false positive results. Further ROC analysis, demonstrated an area under the ROC curve of 0.982, and overall model quality of 0.97. Optimal LVO density cutoff was &lt;0.093 in order to maximize overall accuracy, or &lt; 0.271, in order to maintain a sensitivity of 100% as an absolute priority (both significantly lower than the current threshold of &lt;0.45). Conclusions: Automated software platforms are an invaluable aid in the selection of patients for endovascular thrombectomy. Different LVO detection algorithmic thresholds may be necessary (and should be part of individual stroke center validation pathways) to avoid fatigue alert, and optimize test accuracy, when LVO prevalence is low. Stroke teams should be aware of the limitations of automated analysis and need for expert review.

Back Ground: Rapid Arterial Occlusion Evaluation Scale (RACE) was first instituted in Barcelona and described in 2014 to successfully assess stroke severity and identify patients with acute stroke with large vessel occlusion (LVO) at pre-hospital setting by medical emergency technicians. Objective: We instituted Rapid Arterial Occlusion Evaluation Scale (RACE) hospital bypass protocol (RA) in Lucas county, Ohio since July 2015. Our aim in this study is to evaluate the sensitivity of our RACE protocol in identifying cerebro-vascular accidents and furthermore to identify ischemic CVAs from the cohort. Method: All county EMS personnel (N=464) underwent training in the Rapid Arterial Occlusion Evaluation (RACE) score. The RACE Alert (RA) protocol, whereby patients with stroke symptoms, who were last seen normal less than 12 hours and had a RACE score ≥5 were taken to a facility that has neuro-interventional capacity, was implemented in July 2015. An IRB approved prospective DB was maintained during that period. Patient’s stroke characteristics, type of acute treatment and final diagnosis on discharge were reviewed for the purpose of this abstract. Our results were comparable to the Spanish study done in Barcelona in 2014. Results: Between Jul 2016-Jun 2016 186 RAs were activated. The discharge diagnoses included ischemic stroke N=91 (49%), ICH N=26 (14%) and TIA N=17(9%). The rate of stroke mimic was N=52 (28%) of the total RACE alerts. These included seizures (12%), metabolic encephalotpathy (12%) and others including sepsis and migraines. Of the patients presenting as RA, 33% underwent IV tPA treatment ± mechanical thrombectomy. Conclusion: Results from our prospective county wide data is comparable to prior studies. RACE score may be scalable to other EMS systems to triage potential LVOs for direct transfer to centers with interventional capabilities.

The evaluation and management of acute ischemic stroke has primarily relied on the use of conventional CT and MRI techniques as well as lumen imaging sequences such as CT angiography (CTA) and MR angiography (MRA). Several newer or less-established imaging modalities, including vessel wall MRI, transcranial Doppler ultrasonography, and 4D CTA and MRA, are being developed to complement conventional CT and MRI techniques. Vessel wall MRI provides high-resolution analysis of both extracranial and intracranial vasculature to help identify previously occult lesions or characteristics of lesions that may portend a worse natural history. Transcranial Doppler ultrasonography can be used in the acute setting as a minimally invasive way of identifying large vessel occlusions or monitoring the response to stroke treatment. It can also be used to assist in the workup for cryptogenic stroke or to diagnose a patent foramen ovale. Four-dimensional CTA and MRA provide a less invasive alternative to digital subtraction angiography to determine the extent of the clot burden and the degree of collateral blood flow in large vessel occlusions. Along with technological advances, these new imaging modalities are improving the diagnosis, workup, and management of acute ischemic stroke- roles that will continue to expand in the future.

PMD22 BUDGET IMPACT ANALYSIS OF THE INCORPORATION OF MECHANICAL THROMBECTOMY WITH STENT RETRIEVERS AFTER THROMBOLYSIS IN ISCHEMIC-STROKE WITH LARGE VESSEL OCCLUSION IN THE CHILEAN PUBLIC SECTOR.