Imaging strategy for acute stroke patients, a review of literature

Background: This review article focused on the utilization and impact of current neuroimaging techniques for the patient with acute stroke, emphasizing how imaging builds upon clinical assessment to establish diagnosis or etiology and guide therapeutic decisions. When requesting imaging examinations in patients with stroke symptoms; it is crucial to evaluate four significant parameters of stroke; parenchyma, vessels, perfusion, and penumbra. Evaluation of all these four parameters, in their right request are essential to grasp the explanation and potential therapy decisions for stroke in a specific patient. Extensive neurovascular imaging conventions utilizing multimodality CT (NCCT, CT Angiography, and CT Perfusion) or multimodality MRI (DWI-perfusion mismatch or DWI-FLAIR mismatch, and MR Angiography) might be utilized to evaluate the acute stroke patients and provide all the needed data for treatment of them inside minutes after the patient lands at the emergency clinic. Using this approach will help to discriminate between hemorrhagic and ischemic stroke as presence of frank intracerebral hemorrhage contraindicates reperfusion treatment, permits the choice of patients with large vessel occlusion for endovascular treatment and answer the important “tissue clock” within 6 hours from symptom and even with late-presenting (> 6 h) or wake-up stroke. Conclusions: As patients with acute cerebral stroke might be critically ill, the initial imaging scanning for acute stroke patients should be constrained to the procurement of useful data only, considering the accessible therapeutic options at a given place at any given time.

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Twenty Years of Cerebral Ultrasound Perfusion Imaging—Is the Best yet to Come?

Journal of Clinical Medicine ◽

10.3390/jcm9030816 ◽

2020 ◽

Vol 9 (3) ◽

pp. 816 ◽

Cited By ~ 1

Author(s):

Jens Eyding ◽

Christian Fung ◽

Wolf-Dirk Niesen ◽

Christos Krogias

Keyword(s):

Acute Stroke ◽

Perfusion Imaging ◽

Gold Standard ◽

Ct Perfusion ◽

Intracerebral Hematoma ◽

Stroke Patients ◽

Vessel Occlusion ◽

The Past ◽

To Come ◽

Bedside Method

Over the past 20 years, ultrasonic cerebral perfusion imaging (UPI) has been introduced and validated applying different data acquisition and processing approaches. Clinical data were collected mainly in acute stroke patients. Some efforts were undertaken in order to compare different technical settings and validate results to gold standard perfusion imaging. This review illustrates the evolution of the method, explicating different technical aspects and milestones achieved over time. Up to date, advancements of ultrasound technology as well as data processing approaches enable semi-quantitative, gold standard proven identification of critically hypo-perfused tissue in acute stroke patients. The rapid distribution of CT perfusion over the past 10 years has limited the clinical need for UPI. However, the unexcelled advantage of mobile application raises reasonable expectations for future applications. Since the identification of intracerebral hematoma and large vessel occlusion can also be revealed by ultrasound exams, UPI is a supplementary multi-modal imaging technique with the potential of pre-hospital application. Some further applications are outlined to highlight the future potential of this underrated bedside method of microcirculatory perfusion assessment.

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Effects of state-wide implementation of the Los Angeles Motor Scale for triage of stroke patients in clinical practice

Neurological Research and Practice ◽

10.1186/s42466-021-00128-x ◽

2021 ◽

Vol 3 (1) ◽

Author(s):

Stefanie Behnke ◽

Thomas Schlechtriemen ◽

Andreas Binder ◽

Monika Bachhuber ◽

Mark Becker ◽

...

Keyword(s):

Los Angeles ◽

Acute Stroke ◽

Unsolved Problem ◽

Standard Operating Procedure ◽

Stroke Management ◽

Stroke Patients ◽

Vessel Occlusion ◽

Standard Operating ◽

Los Angeles Motor Scale ◽

Triage Decisions

Abstract Background The prehospital identification of stroke patients with large-vessel occlusion (LVO), that should be immediately transported to a thrombectomy capable centre is an unsolved problem. Our aim was to determine whether implementation of a state-wide standard operating procedure (SOP) using the Los Angeles Motor Scale (LAMS) is feasible and enables correct triage of stroke patients to hospitals offering (comprehensive stroke centres, CSCs) or not offering (primary stroke centres, PSCs) thrombectomy. Methods Prospective study involving all patients with suspected acute stroke treated in a 4-month period in a state-wide network of all stroke-treating hospitals (eight PSCs and two CSCs). Primary endpoint was accuracy of the triage SOP in correctly transferring patients to CSCs or PSCs. Additional endpoints included the number of secondary transfers, the accuracy of the LAMS for detection of LVO, apart from stroke management metrics. Results In 1123 patients, use of a triage SOP based on the LAMS allowed triage decisions according to LVO status with a sensitivity of 69.2% (95% confidence interval (95%-CI): 59.0–79.5%) and a specificity of 84.9% (95%-CI: 82.6–87.3%). This was more favourable than the conventional approach of transferring every patient to the nearest stroke-treating hospital, as determined by geocoding for each patient (sensitivity, 17.9% (95%-CI: 9.4–26.5%); specificity, 100% (95%-CI: 100–100%)). Secondary transfers were required for 14 of the 78 (17.9%) LVO patients. Regarding the score itself, LAMS detected LVO with a sensitivity of 67.5% (95%-CI: 57.1–78.0%) and a specificity of 83.5% (95%-CI: 81.0–86.0%). Conclusions State-wide implementation of a triage SOP requesting use of the LAMS tool is feasible and improves triage decision-making in acute stroke regarding the most appropriate target hospital.

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In-Hospital Intravenous Thrombolysis Offers No Benefit in Mechanical Thrombectomy in Optimized Tertiary Stroke Center Setting

CardioVascular and Interventional Radiology ◽

10.1007/s00270-020-02727-8 ◽

2020 ◽

Author(s):

Juha-Pekka Pienimäki ◽

Jyrki Ollikainen ◽

Niko Sillanpää ◽

Sara Protto

Keyword(s):

Clinical Outcome ◽

Acute Stroke ◽

Mechanical Thrombectomy ◽

Clinical Laboratory ◽

Intravenous Thrombolysis ◽

Stroke Patients ◽

Anterior Circulation ◽

Vessel Occlusion ◽

Ordinal Logistic Regression Analysis ◽

Stroke Center

Abstract Purpose Mechanical thrombectomy (MT) is the first-line treatment in acute stroke patients presenting with large vessel occlusion (LVO). The efficacy of intravenous thrombolysis (IVT) prior to MT is being contested. The objective of this study was to evaluate the efficacy of MT without IVT in patients with no contraindications to IVT presenting directly to a tertiary stroke center with acute anterior circulation LVO. Materials and Methods We collected the data of 106 acute stroke patients who underwent MT in a single high-volume stroke center. Patients with anterior circulation LVO eligible for IVT and directly admitted to our institution who subsequently underwent MT were included. We recorded baseline clinical, laboratory, procedural, and imaging variables and technical, imaging, and clinical outcomes. The effect of intravenous thrombolysis on 3-month clinical outcome (mRS) was analyzed with univariate tests and binary and ordinal logistic regression analysis. Results Fifty-eight out of the 106 patients received IVT + MT. These patients had 2.6-fold higher odds of poorer clinical outcome in mRS shift analysis (p = 0.01) compared to MT-only patients who had excellent 3-month clinical outcome (mRS 0–1) three times more often (p = 0.009). There were no significant differences between the groups in process times, mTICI, or number of hemorrhagic complications. A trend of less distal embolization and higher number of device passes was observed among the MT-only patients. Conclusions MT without prior IVT was associated with an improved overall three-month clinical outcome in acute anterior circulation LVO patients.

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Abstract W P211: Clinical Characteristics of Pseudo Negative Cases in Prehospital Triage for Stroke

Stroke ◽

10.1161/str.46.suppl_1.wp211 ◽

2015 ◽

Vol 46 (suppl_1) ◽

Author(s):

Shuichi Tonomura

Keyword(s):

Acute Stroke ◽

Clinical Characteristics ◽

Stroke Onset ◽

The Other ◽

Small Vessel ◽

Stroke Patients ◽

Vessel Occlusion ◽

Stroke Subtypes ◽

Prehospital Triage ◽

Prehospital Diagnosis

Objective: The accuracy of prehospital diagnosis for stroke by emergency medical services (EMS) is improved using instruments for symptom recognition. On the other hand, prehospital misdiagnosis for stroke and subsequent delay in presentation to a hospital with stroke expertise play a critical role in the exclusion of potential therapeutic candidates. Our study aims to investigate the clinical characteristics of pseudo-negative cases in prehospital triage for stroke/TIA by EMS. Methods: From April 2013 to April 2014, consecutive 644 acute stroke patients were transferred by EMS to our hospital. We investigated prehospital diagnosis, Cincinnati prehospital stroke scale (CPSS) by EMS, neurological symptoms and complaints of patients themselves at stroke onset. We also examined activity of daily life (ADL) and cognitive impairments before stroke onset, and stroke subtypes in final diagnoses. Results: Among 644 acute stroke patients, 36 patients (22 men, mean 72.5±4.4 years old) were pseudo-negative cases in prehospital triage for stroke and had no abnormalities in CPSS by EMS. When EMS arrived at emergency site, 12 patients (33%) had loss of consciousness. Before stroke onset, 6 patients (17%) had impaired ADL (modified Rankin Scale >2), and 5 (14%) cognitive impairment. Among the stroke subtypes, the proportion of small vessel occlusion (22.4%, p=0.0025) and transient ischemic attack (TIA) (25%, p=0.0021) was significant higher in pseudo negative cases in prehospital triage; on the other hand, intracranial hemorrage (11%, p=0.0028) was lower. In complaint of patients themselves at stroke onset, weakness in one or two extremities was reported in 20 patients (56%), abnormal speech/language in 13 (36%), however all of them were not clarified by EMS. Conclusion: This study showed that small vessel occlusion and TIA tend to be misdiagnosed in a prehospital triage by EMS. The complaint of patients themselves at stroke onset is important to prehospital diagnoses by EMS.

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Epidemiological Surveillance of the Impact of the COVID-19 Pandemic on Stroke Care Using Artificial Intelligence

Stroke ◽

10.1161/strokeaha.120.031960 ◽

2021 ◽

Author(s):

Raul G. Nogueira ◽

Jason M. Davies ◽

Rishi Gupta ◽

Ameer E. Hassan ◽

Thomas Devlin ◽

...

Keyword(s):

Artificial Intelligence ◽

Acute Stroke ◽

Systems Of Care ◽

Ct Perfusion ◽

Stroke Care ◽

Large Vessel ◽

Large Vessel Occlusion ◽

Vessel Occlusion ◽

Number Of Patients ◽

The Impact

Background and Purpose: The degree to which the coronavirus disease 2019 (COVID-19) pandemic has affected systems of care, in particular, those for time-sensitive conditions such as stroke, remains poorly quantified. We sought to evaluate the impact of COVID-19 in the overall screening for acute stroke utilizing a commercial clinical artificial intelligence platform. Methods: Data were derived from the Viz Platform, an artificial intelligence application designed to optimize the workflow of patients with acute stroke. Neuroimaging data on suspected patients with stroke across 97 hospitals in 20 US states were collected in real time and retrospectively analyzed with the number of patients undergoing imaging screening serving as a surrogate for the amount of stroke care. The main outcome measures were the number of computed tomography (CT) angiography, CT perfusion, large vessel occlusions (defined according to the automated software detection), and severe strokes on CT perfusion (defined as those with hypoperfusion volumes >70 mL) normalized as number of patients per day per hospital. Data from the prepandemic (November 4, 2019 to February 29, 2020) and pandemic (March 1 to May 10, 2020) periods were compared at national and state levels. Correlations were made between the inter-period changes in imaging screening, stroke hospitalizations, and thrombectomy procedures using state-specific sampling. Results: A total of 23 223 patients were included. The incidence of large vessel occlusion on CT angiography and severe strokes on CT perfusion were 11.2% (n=2602) and 14.7% (n=1229/8328), respectively. There were significant declines in the overall number of CT angiographies (−22.8%; 1.39–1.07 patients/day per hospital, P <0.001) and CT perfusion (−26.1%; 0.50–0.37 patients/day per hospital, P <0.001) as well as in the incidence of large vessel occlusion (−17.1%; 0.15–0.13 patients/day per hospital, P <0.001) and severe strokes on CT perfusion (−16.7%; 0.12–0.10 patients/day per hospital, P <0.005). The sampled cohort showed similar declines in the rates of large vessel occlusions versus thrombectomy (18.8% versus 19.5%, P =0.9) and comprehensive stroke center hospitalizations (18.8% versus 11.0%, P =0.4). Conclusions: A significant decline in stroke imaging screening has occurred during the COVID-19 pandemic. This analysis underscores the broader application of artificial intelligence neuroimaging platforms for the real-time monitoring of stroke systems of care.

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Incorporation of relative cerebral blood flow into CT perfusion maps reduces false ’at risk' penumbra

Journal of NeuroInterventional Surgery ◽

10.1136/neurintsurg-2017-013268 ◽

2017 ◽

Vol 10 (7) ◽

pp. 657-662 ◽

Cited By ~ 2

Author(s):

Shlomi Peretz ◽

David Orion ◽

David Last ◽

Yael Mardor ◽

Yotam Kimmel ◽

...

Keyword(s):

At Risk ◽

Acute Stroke ◽

Ct Perfusion ◽

False Negative ◽

Stroke Patients ◽

True Negative ◽

True Negative Rate ◽

Negative Rate ◽

Perfusion Maps

PurposeThe region defined as ‘at risk’ penumbra by current CT perfusion (CTP) maps is largely overestimated. We aimed to quantitate the portion of true ‘at risk’ tissue within CTP penumbra and to determine the parameter and threshold that would optimally distinguish it from false ‘at risk’ tissue, that is, benign oligaemia.MethodsAmong acute stroke patients evaluated by multimodal CT (NCCT/CTA/CTP) we identified those that had not undergone endovascular/thrombolytic treatment and had follow-up NCCT. Maps of absolute and relative CBF, CBV, MTT, TTP and Tmax as well as summary maps depicting infarcted and penumbral regions were generated using the Intellispace Portal (Philips Healthcare, Best, Netherlands). Follow-up CT was automatically co-registered to the CTP scan and the final infarct region was manually outlined. Perfusion parameters were systematically analysed – the parameter that resulted in the highest true-negative-rate (ie, proportion of benign oligaemia correctly identified) at a fixed, clinically relevant false-negative-rate (ie, proportion of ‘missed’ infarct) of 15%, was chosen as optimal. It was then re-applied to the CTP data to produce corrected perfusion maps.ResultsForty seven acute stroke patients met selection criteria. Average portion of infarcted tissue within CTP penumbra was 15%±2.2%. Relative CBF at a threshold of 0.65 yielded the highest average true-negative-rate (48%), enabling reduction of the false ‘at risk’ penumbral region by ~half.ConclusionsApplying a relative CBF threshold on relative MTT-based CTP maps can significantly reduce false ‘at risk’ penumbra. This step may help to avoid unnecessary endovascular interventions.

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Abstract P355: Real-Word Performance of Two Automated Software Platforms for Identification of Salvageable Tissue in Stroke Patients: A Single Center Experience

Stroke ◽

10.1161/str.52.suppl_1.p355 ◽

2021 ◽

Vol 52 (Suppl_1) ◽

Author(s):

Angelos Katramados ◽

Horia Marin ◽

Maximilian Kole ◽

Owais Alsrouji ◽

Pala Varun ◽

...

Keyword(s):

Ct Perfusion ◽

Stroke Patients ◽

Vessel Occlusion ◽

Significant Discrepancy ◽

Endovascular Thrombectomy ◽

Stroke Treatment ◽

Software Platforms ◽

Automated Software ◽

Selection Of Patients ◽

Selection Of

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 sought to evaluate the performance of these platforms with regard to identification of infarcted and salvageable tissue. Methods: We studied all patients that presented to Henry Ford Health System hospitals over a period of 6 weeks, received CT perfusion imaging of the brain upon initial presentation. The images were processed with two automated software platforms. We prospectively measured volumes of tissue with cerebral blood flow (CBF) < 30% of contralateral hemisphere, Tmax >6 secs, and hypoperfusion indices (defined as the ratio of volumes Tmax>10 secs and Tmax>6 secs). We compared the outputs of the two platforms and analyzed the performance of each platform. Results: 66 scans were included in our study. Both platforms were able to image all stroke patients within their FDA-approved indications. With regard to all scans, both platforms were noted to demonstrate comparable CBF<30% volumes (6.32 ml. vs 4.97 ml, p=0.276), and hypoperfusion indices (0.278 vs 0.338, p=0.344). However, there was statistically significant discrepancy in the volumes of tissue with Tmax>6 secs (23.96 vs 14.18 ml, p=0.023). Analysis of a subset of 12 scans, with evidence of LVO or severe symptomatic stenosis on corresponding CTA, showed again comparable CBF<30% volumes (12.84 ml vs 13.67 ml, p=0.725), and hypoperfusion indices (0.344 vs 0.314, p=0.699). However, the Tmax>6 secs volume discrepancy was greater and still statistically significant (75.54 ml vs 39.58 ml, p=0.048) Conclusions: Automated software platforms are an invaluable aid in the identification of salvageable tissue, and selection of patients for endovascular thrombectomy in the 6-24 hour window. However, the substantial difference in the identified volumes of hypoperfused tissue-at-risk may result in largely different clinical decisions and patient outcomes. Further validation efforts (and harmonization of algorithms) are required. Stroke teams should be aware of the limitations of automated analysis and need for expert review.

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Abstract TMP1: Predicting Scale Design and Derivation to Select Acute Ischemic Stroke Patients for Direct Angiosuite Intervention

Stroke ◽

10.1161/str.51.suppl_1.tmp1 ◽

2020 ◽

Vol 51 (Suppl_1) ◽

Author(s):

Zeguang Ren ◽

Runqi Wangqin ◽

Maxim Mokin ◽

Anxin Wang ◽

Liang Zhao ◽

...

Keyword(s):

Ischemic Stroke ◽

Acute Stroke ◽

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Vascular Imaging ◽

Operating Characteristics ◽

Stroke Patients ◽

Additional Time ◽

Vessel Occlusion

Introduction: Vascular imaging after head CT to confirm large vessel occlusion (LVO) for acute stroke patients requires additional time and delays recanalization. We developed the T hrombectomy A cute M echanical re P erfusion A ssessment ( TAMPA ) scale for selecting patients with LVO for direct angiosuite transfer and intervention to improve recanalization time. Methods: The TAMPA scale was developed from our prospectively collected “Get with the Guidelines” database. We included all “stroke alert” patients between 1/2017 and 8/2018 with vascular imaging and National Institutes of Health Stroke Scale scores between 5 and 25. We excluded patients with immediately obvious non-stroke diagnoses, those lacking subsequent vascular imaging, or those with incomplete records. Different variables were collected. The TAMPA scale receiver operating characteristics curve (ROC) was compared with the ROCs of other commonly used scales. Results: 571 eligible patients from 2115 “acute stroke alerts” were identified for developing the TAMPA scale. The scale was established with a combination of 5 items with a total score of 9: CT hyperdense sign, parenchymal hypodensity, lateralizing hemiparalysis, gaze deviation and speech disturbance. A cutoff of ≥ 4 yielded a sensitivity of 68.98%, specificity of 72.91%, false positive rate of 27.09%, and false negative rate of 31.02%. Compared with other scales, such as total NIHSS, C-stat/CPSSS, RACE, FAST-ED and 3I-SS, the TAMPA scale had the best ROC for the selected group of patients. Conclusions: The TAMPA scale accurately predicts presence of clinically amenable LVO in patients with moderate to severe ischemic stroke. Use of the TAMPA scale to identify high probability mechanical embolectomy candidates for direct transfer to the angiosuite could potentially reduce revascularization times and increase treatment rates.

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