Outcomes with General Anesthesia Compared to Conscious Sedation for Endovascular Treatment of Medium Vessel Occlusions: Results of an International Multicentric Study

BACKGROUND

Optimal anesthetic strategy for the endovascular treatment of stroke is still under debate. Despite scarce data concerning anesthetic management for medium and distal vessel occlusions (MeVOs) some centers empirically support a general anesthesia (GA) strategy in these patients.

METHODS

We conducted an international retrospective study of MeVO cases. A propensity score matching algorithm was used to mitigate potential differences across patients undergoing GA and conscious sedation (CS). Comparisons in clinical and safety outcomes were performed between the two study groups GA and CS. The favourable outcome was defined as a modified Rankin Scale (mRS) 0-2 at 90 days. Safety outcomes were 90-days mortality and symptomatic intracranial hemorrhage (sICH). Predictors of a favourable outcome and sICH were evaluated with backward logistic regression.

RESULTS

After propensity score matching 668 patients were included in the CS and 264 patients in the GA group. In the matched cohort, either strategy CS or GA resulted in similar rates of good functional outcomes (50.1% vs. 48.4%), and successful recanalization (89.4% vs. 90.2%). The GA group had higher rates of 90-day mortality (22.6% vs. 16.5%, p < 0.041) and sICH (4.2% vs. 0.9%, p = 0.001) compared to the CS group. Backward logistic regression did not identify GA vs CS as a predictor of good functional outcome (OR for GA vs CS = 0.95 (0.67-1.35)), but GA remained a significant predictor of sICH (OR = 5.32, 95% CI 1.92-14.72).

CONCLUSION

Anaesthetic strategy in MeVOs does not influence favorable outcomes or final successful recanalization rates, however, GA may be associated with an increased risk of sICH and mortality.

Incidence and clinical outcomes of perforations during mechanical thrombectomy for medium vessel occlusion in acute ischemic stroke: A retrospective, multicenter, and multinational study

BACKGROUND

Mechanical thrombectomy (MT) has revolutionized the treatment of acute ischemic stroke (AIS) due to large vessel occlusion (LVO), but its efficacy and safety in medium vessel occlusion (MeVO) remain less explored. This multicenter, retrospective study aims to investigate the incidence and clinical outcomes of vessel perforations (confirmed by extravasation during an angiographic series) during MT for AIS caused by MeVO.

METHODS

Data were collected from 37 academic centers across North America, Asia, and Europe between September 2017 and July 2021. A total of 1373 AIS patients with MeVO underwent MT. Baseline characteristics, procedural details, and clinical outcomes were analyzed.

RESULTS

The incidence of vessel perforation was 4.8% (66/1373). Notably, our analysis indicates variations in perforation rates across different arterial segments: 8.9% in M3 segments, 4.3% in M2 segments, and 8.3% in A2 segments (p = 0.612). Patients with perforation had significantly worse outcomes, with lower rates of favorable angiographic outcomes (TICI 2c-3: 23% vs 58.9%, p < 0.001; TICI 2b-3: 56.5% vs 88.3%, p < 0.001). Functional outcomes were also worse in the perforation group (mRS 0-1 at 3 months: 22.7% vs 36.6%, p = 0.031; mRS 0-2 at 3 months: 28.8% vs 53.9%, p < 0.001). Mortality was higher in the perforation group (30.3% vs 16.8%, p = 0.008).

CONCLUSION

This study reveals that while the occurrence of vessel perforation in MT for AIS due to MeVO is relatively rare, it is associated with poor functional outcomes and higher mortality. The findings highlight the need for increased caution and specialized training in performing MT for MeVO. Further prospective research is required for risk mitigation strategies.

Automated assessment of ischemic core on non-contrast computed tomography: a multicenter comparative analysis with CT perfusion

BACKGROUND

Application of machine learning (ML) algorithms has shown promising results in estimating ischemic core volumes using non-contrast CT (NCCT).

OBJECTIVE

To assess the performance of the e-Stroke Suite software (Brainomix) in assessing ischemic core volumes on NCCT compared with CT perfusion (CTP) in patients with acute ischemic stroke.

METHODS

In this retrospective multicenter study, patients with anterior circulation large vessel occlusions who underwent pretreatment NCCT and CTP, successful reperfusion (modified Thrombolysis in Cerbral Infarction ≥2b), and post-treatment MRI, were included from three stroke centers. Automated calculation of ischemic core volumes was obtained on NCCT scans using ML algorithm deployed by e-Stroke Suite and from CTP using Olea software (Olea Medical). Comparative analysis was performed between estimated core volumes on NCCT and CTP and against MRI calculated final infarct volume (FIV).

RESULTS

A total of 111 patients were included. Estimated ischemic core volumes (mean±SD, mL) were 20.4±19.0 on NCCT and 19.9±18.6 on CTP, not significantly different (P=0.82). There was moderate (r=0.40) and significant (P<0.001) correlation between estimated core on NCCT and CTP. The mean difference between FIV and estimated core volume on NCCT and CTP was 29.9±34.6 mL and 29.6±35.0 mL, respectively (P=0.94). Correlations between FIV and estimated core volume were similar for NCCT (r=0.30, P=0.001) and CTP (r=0.36, P<0.001).

CONCLUSIONS

Results show that ML-based estimated ischemic core volumes on NCCT are comparable to those obtained from concurrent CTP in magnitude and in degree of correlation with MR-assessed FIV.

CTP-based estimated ischemic core: A comparative multicenter study between Olea and RAPID software

BACKGROUND AND PURPOSE

CTP is increasingly used to assess eligibility for endovascular therapy (EVT) in patients with large vessel occlusions (LVO). There remain variability and inconsistencies between software packages for estimation of ischemic core. We aimed to use heterogenous data from four stroke centers to perform a comparative analysis for CTP-estimated ischemic core between RAPID (iSchemaView) and Olea (Olea Medical).

METHODS

In this retrospective multicenter study, patients with anterior circulation LVO who underwent pretreatment CTP, successful EVT (defined TICI ≥ 2b), and follow-up MRI included. Automated CTP analysis was performed using Olea platform [rCBF < 25% and differential time-to-peak (dTTP)>5s] and RAPID (rCBF < 30%). The CTP estimated core volumes were compared against the final infarct volume (FIV) on post treatment MRI-DWI.

RESULTS

A total of 151 patients included. The CTP-estimated ischemic core volumes (mean ± SD) were 18.7 ± 18.9 mL on Olea and 10.5 ± 17.9 mL on RAPID significantly different (p < 0.01). The correlation between CTP estimated core and MRI final infarct volume was r = 0.38, p < 0.01 for RAPID and r = 0.39, p < 0.01 for Olea. Both software platforms demonstrated a strong correlation with each other (r = 0.864, p < 0.001). Both software overestimated the ischemic core volume above 70 mL in 4 patients (2.6%).

CONCLUSIONS

Substantial variation between Olea and RAPID CTP-estimated core volumes exists, though rates of overcalling of large core were low and identical. Both showed comparable core volume correlation to MRI infarct volume.

Trends in Disparities in Advanced Neuroimaging Utilization in Acute Stroke: A Population-Based Study

Background:

Our primary objective was to evaluate if disparities in race, sex, age, and socioeconomic status (SES) exist in utilization of advanced neuroimaging in year 2015 in a population-based study. Our secondary objective was to identify the disparity trends and overall imaging utilization as compared with years 2005 and 2010.

Methods:

This was a retrospective, population-based study that utilized the GCNKSS (Greater Cincinnati/Northern Kentucky Stroke Study) data. Patients with stroke and transient ischemic attack were identified in the years 2005, 2010, and 2015 in a metropolitan population of 1.3 million. The proportion of imaging use within 2 days of stroke/transient ischemic attack onset or hospital admission date was computed. SES determined by the percentage below the poverty level within a given respondent’s US census tract of residence was dichotomized. Multivariable logistic regression was used to determine the odds of advanced neuroimaging use (computed tomography angiogram/magnetic resonance imaging/magnetic resonance angiogram) for age, race, gender, and SES.

Results:

There was a total of 10 526 stroke/transient ischemic attack events in the combined study year periods of 2005, 2010, and 2015. The utilization of advanced imaging progressively increased (48% in 2005, 63% in 2010, and 75% in 2015 [ P <0.001]). In the combined study year multivariable model, advanced imaging was associated with age and SES. Younger patients (≤55 years) were more likely to have advanced imaging compared with older patients (adjusted odds ratio, 1.85 [95% CI, 1.62–2.12]; P <0.01), and low SES patients were less likely to have advanced imaging compared with high SES (adjusted odds ratio, 0.83 [95% CI, 0.75–0.93]; P <0.01). A significant interaction was found between age and race. Stratified by age, the adjusted odds of advanced imaging were higher for Black patients compared with White patients among older patients (>55 years; adjusted odds ratio, 1.34 [95% CI, 1.15–1.57]; P <0.01), but no racial differences among the young.

Conclusions:

Racial, age, and SES-related disparities exist in the utilization of advanced neuroimaging for patients with acute stroke. There was no evidence of a change in trend of these disparities between the study periods.

The relevance of rich club regions for functional outcome post-stroke is enhanced in women

This study aimed to investigate the influence of stroke lesions in predefined highly interconnected (rich-club) brain regions on functional outcome post-stroke, determine their spatial specificity and explore the effects of biological sex on their relevance. We analyzed MRI data recorded at index stroke and ~3-months modified Rankin Scale (mRS) data from patients with acute ischemic stroke enrolled in the multisite MRI-GENIE study. Spatially normalized structural stroke lesions were parcellated into 108 atlas-defined bilateral (sub)cortical brain regions. Unfavorable outcome (mRS > 2) was modeled in a Bayesian logistic regression framework. Effects of individual brain regions were captured as two compound effects for (i) six bilateral rich club and (ii) all further non-rich club regions. In spatial specificity analyses, we randomized the split into "rich club" and "non-rich club" regions and compared the effect of the actual rich club regions to the distribution of effects from 1000 combinations of six random regions. In sex-specific analyses, we introduced an additional hierarchical level in our model structure to compare male and female-specific rich club effects. A total of 822 patients (age: 64.7[15.0], 39% women) were analyzed. Rich club regions had substantial relevance in explaining unfavorable functional outcome (mean of posterior distribution: 0.08, area under the curve: 0.8). In particular, the rich club-combination had a higher relevance than 98.4% of random constellations. Rich club regions were substantially more important in explaining long-term outcome in women than in men. All in all, lesions in rich club regions were associated with increased odds of unfavorable outcome. These effects were spatially specific and more pronounced in women.

Radiomics-Derived Brain Age Predicts Functional Outcome After Acute Ischemic Stroke

BACKGROUND AND OBJECTIVES

While chronological age is one of the most influential determinants of poststroke outcomes, little is known of the impact of neuroimaging-derived biological "brain age." We hypothesized that radiomics analyses of T2-FLAIR images texture would provide brain age estimates and that advanced brain age of patients with stroke will be associated with cardiovascular risk factors and worse functional outcomes.

METHODS

We extracted radiomics from T2-FLAIR images acquired during acute stroke clinical evaluation. Brain age was determined from brain parenchyma radiomics using an ElasticNet linear regression model. Subsequently, relative brain age (RBA), which expresses brain age in comparison with chronological age-matched peers, was estimated. Finally, we built a linear regression model of RBA using clinical cardiovascular characteristics as inputs and a logistic regression model of favorable functional outcomes taking RBA as input.

RESULTS

We reviewed 4,163 patients from a large multisite ischemic stroke cohort (mean age = 62.8 years, 42.0% female patients). T2-FLAIR radiomics predicted chronological ages (mean absolute error = 6.9 years, r = 0.81). After adjustment for covariates, RBA was higher and therefore described older-appearing brains in patients with hypertension, diabetes mellitus, a history of smoking, and a history of a prior stroke. In multivariate analyses, age, RBA, NIHSS, and a history of prior stroke were all significantly associated with functional outcome (respective adjusted odds ratios: 0.58, 0.76, 0.48, 0.55; all p-values < 0.001). Moreover, the negative effect of RBA on outcome was especially pronounced in minor strokes.

DISCUSSION

T2-FLAIR radiomics can be used to predict brain age and derive RBA. Older-appearing brains, characterized by a higher RBA, reflect cardiovascular risk factor accumulation and are linked to worse outcomes after stroke.

Accuracy of CT perfusion-predicted core in the late window

BACKGROUND AND PURPOSE

Recent endovascular trials have spurred a paradigm shift toward routine use of CT perfusion (CTP) for decision-making in acute ischemic stroke. CTP use in the late window, however, remains under evaluation. Our objective was to assess the accuracy of CTP-predicted core in the late window.

METHODS

In a retrospective review of our prospectively identified stroke registry at a single, comprehensive stroke center, we included patients with anterior large vessel occlusions presenting within the 6-24 h window who underwent baseline CTP evaluation and achieved TICI2b or TICI3 reperfusion on endovascular treatment. We recorded baseline CTP-predicted core volumes at relative cerebral blood flow (CBF) thresholds of <30% <34%, and <38% using RAPID software. Final infarct volumes (FIV) were calculated using follow up MRI and CT, obtained within 72 h after stroke onset.

RESULTS

Of the eligible patients, 134 met our inclusion criteria. Mean FIV was 39.5 (SD 49.6). Median CTP to reperfusion time was 93.5 min. Median absolute differences between CTP-predicted core and FIV were 14.7, 14.9, and 16.0 ml at <30%, <34%, and <38%, respectively. Correlation between CTP-predicted ischemic cores and FIV was moderate and statistically significant at all thresholds: r = 0.43 (p <0.001), r = 0.43 (p <0.001), and r = 0.42 (p <0.001) at the <30%, <34%, and <38% cutoffs, respectively.

CONCLUSION

CTP cores in the 6-24 h period underestimate FIV, especially with larger infarcts. CTP-predicted core volumes in the late window show moderate positive correlation with FIV.

Association of Stroke Lesion Pattern and White Matter Hyperintensity Burden With Stroke Severity and Outcome

BACKGROUND AND OBJECTIVES

To examine whether high white matter hyperintensity (WMH) burden is associated with greater stroke severity and worse functional outcomes in lesion pattern-specific ways.

METHODS

MR neuroimaging and NIH Stroke Scale data at index stroke and the modified Rankin Scale (mRS) score at 3-6 months after stroke were obtained from the MRI-Genetics Interface Exploration study of patients with acute ischemic stroke (AIS). Individual WMH volume was automatically derived from fluid-attenuated inversion recovery images. Stroke lesions were automatically segmented from diffusion-weighted imaging (DWI) images, parcellated into atlas-defined brain regions and further condensed to 10 lesion patterns via machine learning-based dimensionality reduction. Stroke lesion effects on AIS severity and unfavorable outcomes (mRS score >2) were modeled within purpose-built Bayesian linear and logistic regression frameworks. Interaction effects between stroke lesions and a high vs low WMH burden were integrated via hierarchical model structures. Models were adjusted for age, age2, sex, total DWI lesion and WMH volumes, and comorbidities. Data were split into derivation and validation cohorts.

RESULTS

A total of 928 patients with AIS contributed to acute stroke severity analyses (age: 64.8 [14.5] years, 40% women) and 698 patients to long-term functional outcome analyses (age: 65.9 [14.7] years, 41% women). Stroke severity was mainly explained by lesions focused on bilateral subcortical and left hemispherically pronounced cortical regions across patients with both a high and low WMH burden. Lesions centered on left-hemispheric insular, opercular, and inferior frontal regions and lesions affecting right-hemispheric temporoparietal regions had more pronounced effects on stroke severity in case of high compared with low WMH burden. Unfavorable outcomes were predominantly explained by lesions in bilateral subcortical regions. In difference to the lesion location-specific WMH effects on stroke severity, higher WMH burden increased the odds of unfavorable outcomes independent of lesion location.

DISCUSSION

Higher WMH burden may be associated with an increased stroke severity in case of stroke lesions involving left-hemispheric insular, opercular, and inferior frontal regions (potentially linked to language functions) and right-hemispheric temporoparietal regions (potentially linked to attention). Our findings suggest that patients with specific constellations of WMH burden and lesion locations may have greater benefits from acute recanalization treatments. Future clinical studies are warranted to systematically assess this assumption and guide more tailored treatment decisions.

Deep profiling of multiple ischemic lesions in a large, multi-center cohort: Frequency, spatial distribution, and associations to clinical characteristics

Background purpose

A substantial number of patients with acute ischemic stroke (AIS) experience multiple acute lesions (MAL). We here aimed to scrutinize MAL in a large radiologically deep-phenotyped cohort.

Materials and methods

Analyses relied upon imaging and clinical data from the international MRI-GENIE study. Imaging data comprised both Fluid-attenuated inversion recovery (FLAIR) for white matter hyperintensity (WMH) burden estimation and diffusion-weighted imaging (DWI) sequences for the assessment of acute stroke lesions. The initial step featured the systematic evaluation of occurrences of MAL within one and several vascular supply territories. Associations between MAL and important imaging and clinical characteristics were subsequently determined. The interaction effect between single and multiple lesion status and lesion volume was estimated by means of Bayesian hierarchical regression modeling for both stroke severity and functional outcome.

Results

We analyzed 2,466 patients (age = 63.4 ± 14.8, 39% women), 49.7% of which presented with a single lesion. Another 37.4% experienced MAL in a single vascular territory, while 12.9% featured lesions in multiple vascular territories. Within most territories, MAL occurred as frequently as single lesions (ratio ∼1:1). Only the brainstem region comprised fewer patients with MAL (ratio 1:4). Patients with MAL presented with a significantly higher lesion volume and acute NIHSS (7.7 vs. 1.7 ml and 4 vs. 3, p FDR < 0.001). In contrast, patients with a single lesion were characterized by a significantly higher WMH burden (6.1 vs. 5.3 ml, p FDR = 0.048). Functional outcome did not differ significantly between patients with single versus multiple lesions. Bayesian analyses suggested that the association between lesion volume and stroke severity between single and multiple lesions was the same in case of anterior circulation stroke. In case of posterior circulation stroke, lesion volume was linked to a higher NIHSS only among those with MAL.

Conclusion

Multiple lesions, especially those within one vascular territory, occurred more frequently than previously reported. Overall, multiple lesions were distinctly linked to a higher acute stroke severity, a higher total DWI lesion volume and a lower WMH lesion volume. In posterior circulation stroke, lesion volume was linked to a higher stroke severity in multiple lesions only.

Recombinant factor VIIa for hemorrhagic stroke treatment at earliest possible time (FASTEST): Protocol for a phase III, double-blind, randomized, placebo-controlled trial

INTRODUCTION

Intracerebral hemorrhage is the deadliest form of stroke. Hematoma expansion, growth of the hematoma between the baseline computed tomography scan and a follow-up computed tomography scan at 24 ± 6 h, predicts long-term disability or death. Recombinant factor VIIa (rFVIIa) has reduced hematoma expansion in previous clinical trials with a variable effect on clinical outcomes, with the greatest impact on hematoma expansion and potential benefit when administered within 2 h of symptom onset.

METHODS

Factor VIIa for Hemorrhagic Stroke Treatment at Earliest Possible Time (FASTEST, NCT03496883) is a randomized controlled trial that will enroll 860 patients at ∼100 emergency departments and mobile stroke units in five countries. Patients are eligible for enrollment if they have acute intracerebral hemorrhage within 2 h of symptom onset confirmed by computed tomography, a hematoma volume of 2 to 60 mL, no or small volumes of intraventricular hemorrhage, do not take anticoagulant medications or concurrent heparin/heparinoids (antiplatelet medications are permissible), and are not deeply comatose. Enrolled patients will receive rFVIIa 80 µg/kg or placebo intravenously over 2 min. The primary outcome measure is the distribution of the ordinal modified Rankin Scale at 180 days. FASTEST is monitored by a Data Safety Monitoring Board. Safety endpoints include thrombotic events (e.g. myocardial infarction). Human subjects research is monitored by an external Institutional Review Board in participating countries.

DISCUSSION

In the US, FASTEST will be first NIH StrokeNet Trial with an Exception from Informed Consent which allows enrollment of non-communicative patients without an immediately identifiable proxy.

Small Vessel Disease, a Marker of Brain Health: What the Radiologist Needs to Know

Small vessel disease, a disorder of cerebral microvessels, is an expanding epidemic and a common cause of stroke and dementia. Despite being almost ubiquitous in brain imaging, the clinicoradiologic association of small vessel disease is weak, and the underlying pathogenesis is poorly understood. The STandards for ReportIng Vascular changes on nEuroimaging (STRIVE) criteria have standardized the nomenclature. These include white matter hyperintensities of presumed vascular origin, recent small subcortical infarcts, lacunes of presumed vascular origin, prominent perivascular spaces, cerebral microbleeds, superficial siderosis, cortical microinfarcts, and brain atrophy. Recently, the rigid categories among cognitive impairment, vascular dementia, stroke, and small vessel disease have become outdated, with a greater emphasis on brain health. Conventional and advanced small vessel disease imaging markers allow a comprehensive assessment of global brain heath. In this review, we discuss the pathophysiology of small vessel disease neuroimaging nomenclature by means of the STRIVE criteria, clinical implications, the role of advanced imaging, and future directions.

Abstract TP137: Ethnic/racial Variations Of Intracerebral Hemorrhage Genetics (erich-gene) Study Protocol

Introduction: Epidemiologic studies of intracerebral hemorrhage (ICH) have consistently demonstrated variation in incidence, location, comorbidity burden, age-of-onset, and outcome by race and ethnicity, and genetic studies have identified differences in risk mediated by genetic risk factors such as Apolipoprotein E (APOE). We report the design and methods of the largest multi-ethnic genome-wide association study (GWAS) of ICH risk and outcome conducted to date.

Methods: The Ethnic/Racial Variations of ICH Genetics (ERICH-GENE) study is an international, multi-center, genetic case-control study of ICH. Cases are individuals with confirmed primary ICH with biosample availability and consent compatible with shareable genome-wide genotyping or previous genotyping. Central neuroimaging phenotype harmonization of case status, hemorrhage location, and imaging characteristics of cerebral small vessel disease including leukoaraiosis, atrophy, microbleeds, intraventricular hemorrhage severity and volume of ICH measurements will be performed. Controls are ICH-free individuals of compatible age and race/ethnicity from existing studies and biorepositories.

Results: As of August 2021, 2,002 ICH cases have been collected and genotyped, in addition to 2,558 already-genotyped ICH cases from the multi-ethnic ERICH study. 5,600 total new ICH cases will be genotyped under ERICH-GENE, with planned meta-analyses across existing ICH GWAS datasets and international biobanks totaling >20,000 cases. We are on schedule to meet our genotyping goal within the study period. Non-European ancestry cases are being prioritized for genotyping and ~66% of the previously genotyped ERICH cases are black or Hispanic. From available cases, a total of 10,621 neuroimaging studies have been uploaded for central adjudication to date with 6,278 having undergone harmonization.

Conclusions: ERICH-GENE is a large, multi-ethnic, international, centrally harmonized GWAS of ICH risk and outcome that will identify genetic risk factors across diverse populations for biological discovery and population-specific risk stratification.

Abstract WMP82: Diffusion Tensor Imaging Is Independently Associated With Mobility After Intracerebral Hemorrhage

Background: Intracerebral hemorrhage (ICH) patients may appear disabled despite intact cortical spinal tracts (CST). ICH lesions may also vary in volume and location relative to the CST with differential impacts on motor outcome. In this study, we evaluated whether diffusion tensor imaging (DTI) integrity of CST fiber tracking associates with mobility three months post ICH.

Methods: The Recovery and Outcomes from StrokE (ROSE) Study is a prospective, multi-center study of ICH serially assessed with motor, cognitive, and functional outcomes and MRI/DTI. Outcome data were collected by hospital chart review and interview/exam. Acute MRI images were analyzed by a central neuroimaging core for ICH location, size, intraventricular hemorrhage, and fractional anisotropy (FA) derived from DTI of the CST. Mobility was assessed at 3-month follow-up using the Barthel Mobility Index. We computed single variable logistic regression analyses (outcome = Barthel mobility at 3 months). We also computed a stepwise logistic model, with and without age, sex, and race, including variables that met P<0.1 to best fit.

Results: There were 76 ICH patients with DTI FA data available for analysis; 61 with complete data for the multivariate model. Poor mobility after ICH (N = 21; 27.6%) was associated with ICH volume, presence of IVH, Glasgow coma score, ipsilesional CST FA, ipsilesional CP FA and CP FA asymmetry index (Table 1). The multivariate model that adjusted for age, sex, and race identified ipsilesional CP FA, admission GCS and presence of IVH as associated with poor mobility at 3 months; notably, log ICH volume was not associated after controlling for CST injury (Table 1).

Conclusions: The presence of IVH and the GCS score at baseline were associated with poor mobility. In addition, the CP FA asymmetry index was independently associated with poor mobility even after accounting for log ICH volume, suggesting that DTI is informative of outcome beyond classic ICH outcome predictors.

Abstract TP101: Defining Ischemic Core In Acute Ischemic Stroke Using CT Perfusion: A Multi-center Validation Study

Background: Estimation of infarction based on computed tomographic perfusion (CTP) remains challenging, mainly due to noise associated with CTP data and variability in reported thresholds ischemic core esstimation. Commercial software companies have attempted to establish CTP thresholds; for example, a relative cerebral blood flow (rCBF) of <30% for RAPID™ (iSchemaView). In this retrospective multi-center study, we sought to establish and validate CTP threshold values for estimation of ischemic core using Olea Sphere® software (Olea Medical Solutions).

Methods: Under an approved multi-institutional protocol, patients with acute ischemic stroke of the anterior circulation from three comprehensive stroke centers were included if they met the following criteria: baseline CTP, recanalization achieved (Thrombolysis in cerebral infarction scale ≥ IIb), and follow up MRI (DWI) performed. Perfusion maps were generated from the CTP data by the Bayesian probabilistic model and oscillation singular value decomposition (oSVD). CTP parameters, including time to peak (TTP), rCBF, time to max (Tmax), and Delay (equivalent of Tmax in Bayesian model) were generated. Brain was extracted from CTP and coregistered with the follow up MRI. An infarction mask and non-infarcted masks were drawn on MRI. We used a robust logistic regression to assess the binary outcome of our voxel-based analysis (infarcted vs non-infarcted) by adjusting for intra-subject correlations.

Results: Eighty-one patients (42 Male; mean age 67.4 ±17.3) were included. All CTP parameters for the Bayesian and oSVD methods showed significant differences between infarcted and non-infarcted areas (p < 0.001). In the Bayesian model, a combination of rCBF at threshold of <45% and delay at threshold of 0.82 sec provided the highest diagnostic accuracy; AUC/sensitivity/specificity (0.79/0.69/0.79). In the oSVD method, a combination of rCBF at threshold of <16% and Tmax at threshold of 4.00 sec provided the highest diagnostic accuracy; AUC/sensitivity/specificity (0.71/0.64/0.73).

Conclusion: Using heterogenous CTP data from three stroke centers, we established thresholds for estimation of ischemic core for Olea software that can be used for both Bayesian and oSVD postprocessing models.

Abstract TP10: Inflammatory And Neurodegenerative Gene Expression Changes Occur Long-term After ICH

Objective: There is a high prevalence of progressive cognitive impairment in intracerebral hemorrhage (ICH) survivors. We sought to identify gene expression changes, in association with long-term neurodegeneration, among patients 12-24 months post-ICH.

Methods: The Recovery and Outcomes from StrokE (ROSE) study prospectively recruits patients with spontaneous, supratentorial ICH, collecting baseline peripheral blood samples and MRI with diffusion tract imaging (DTI). The Recovery of StrokE-Longitudinal Assessment with Neuroimaging (ROSE-LAWN) study performs long term follow-up at 12-24 months on cases enrolled in ROSE. We report on the first five cases enrolled in the ROSE-LAWN study from December 2020 to March 2021. Controls were matched to an overall ICH population by age, sex, and race. RNA-sequencing, aligned to human genome assembly GRCh38, was tested for differential gene expression. Canonical pathway enrichment and network analyses were computed for differentially expressed genes using Ingenuity Pathway Analysis, STRING and MCODE.

Results: RNA-seq analysis of 5 ICH cases [male, 80%; median age, 61 (45 - 73); black, 40%; ICH volume, 14.88cc ± 13.07] and 13 controls [male, 54%; median age, 74 (69 - 79); black, 15%] identified 554 differentially expressed genes (genomic control adjusted p < 0.01), of which 24 met the false discovery rate correction for multiple comparisons (FDR < 0.05). The most significant difference was observed in hypoxia up-regulated 1 ( HYOU1), a heat shock protein related gene (p = 2.64E-11). Pathway analysis identified enrichment of dopamine and serotonin receptor signaling (p = 8.74E-03, 2.23E-02), cell cycle regulation (p = 1.75E-02) and agranulocyte adhesion pathways (p = 2.18E-02). Comparison of baseline and follow-up MRI DTI demonstrated extensive cortical tract degeneration, beyond the initial injury.

Conclusion: These results provide novel evidence of significant gene expression changes occurring years after the initial ICH. Despite resolution of the ICH, persistent inflammation may correlate with progressive neurodegeneration and subsequent cognitive impairment in ICH survivors. Future studies with greater sample sizes are supported by this work.

Abstract WP107: Differences In Automated Perfusion Softwares: Do They Matter Clinically?

Introduction: Treatment of acute ischemic stroke in the late window changed with the positive results of DAWN and DEFUSE III. Both trials required the use of automated perfusion software for inclusion. Because differences in the predicted core or penumbra between software can lead to differences in eligibility for endovascular thrombectomy (EVT), we sought to compare whether these potential differences would have changed eligibility for EVT by DAWN or DEFUSE III criteria.

Methods: Patients presenting or transferred to the University of Cincinnati Medical Center between April 23 rd 2019 and July 22 nd 2019 with acute ischemic stroke secondary to large vessel occlusions within the anterior circulation in the extended time window (>6-24 hours) who underwent CT perfusion (CTP) imaging were prospectively tracked. CTP findings, clinical course, age and initial NIHSS were retrospectively reviewed. The primary outcome was EVT eligibility using DAWN or DEFUSE criteria. Secondary outcomes were penumbra (Tmax>6s) and core (CBF<30%) volumes. McNemar test and kappa coefficients were used to assess the agreement in the primary outcome. Intra-class correlation coefficients were used to evaluate the agreement between the software for secondary outcomes.

Results: Of 46 included patients, the Viz CTP and RAPID software provided discordant EVT eligibility in 5 cases (4 by DEFUSE criteria and 1 by DAWN). By DAWN criteria, agreement was almost perfect between the software packages (kappa 0.96, 95% CI 0.87-1.00, p<0.0001). By DEFUSE III criteria, the two software demonstrated excellent agreement (kappa 0.82, 95% CI 0.65-0.99, p<0.0001).

Discussion: We observed no difference in eligibility for EVT using either software when both DEFUSE and DAWN criteria were considered. If using only one trial’s criteria, 10.6% of patients would have had differing eligibility for EVT depending on the package used, although this difference did not demonstrate statistical significance.

Catastrophic Cerebral Fat Embolism Syndrome Lacks Hyperacute MRI Findings

A 64-year-old female with sickle cell (hemoglobin SC) disease and prior embolic strokes was admitted for vaso-occlusive pain crisis and developed sudden onset coma. Hyperacute brain MRI showed only small areas of mismatch between diffusion weighted imaging (DWI) and T2 fluid attenuated inversion recovery (T2 FLAIR) sequences that were insufficient to explain her profoundly altered level of consciousness. Repeat MRI 24 hours later showed innumerable foci of restricted diffusion and petechial microhemorrhage, confirming a diagnosis of cerebral fat embolism due to sickle cell crisis.

OUP accepted manuscript

Stroke represents a considerable burden of disease for both men and women. However, a growing body of literature suggests clinically relevant sex differences in the underlying causes, presentations and outcomes of acute ischaemic stroke. In a recent study, we reported sex divergences in lesion topographies: specific to women, acute stroke severity was linked to lesions in the left-hemispheric posterior circulation. We here determined whether these sex-specific brain manifestations also affect long-term outcomes. We relied on 822 acute ischaemic patients [age: 64.7 (15.0) years, 39% women] originating from the multi-centre MRI-GENIE study to model unfavourable outcomes (modified Rankin Scale >2) based on acute neuroimaging data in a Bayesian hierarchical framework. Lesions encompassing bilateral subcortical nuclei and left-lateralized regions in proximity to the insula explained outcomes across men and women (area under the curve = 0.81). A pattern of left-hemispheric posterior circulation brain regions, combining left hippocampus, precuneus, fusiform and lingual gyrus, occipital pole and latero-occipital cortex, showed a substantially higher relevance in explaining functional outcomes in women compared to men [mean difference of Bayesian posterior distributions (men – women) = −0.295 (90% highest posterior density interval = −0.556 to −0.068)]. Once validated in prospective studies, our findings may motivate a sex-specific approach to clinical stroke management and hold the promise of enhancing outcomes on a population level.

Association Between CT Angiogram Collaterals and CT Perfusion in Delayed Time Windows for Large Vessel Occlusion Ischemic Strokes

OBJECTIVES

Recent endovascular trials have established the use of CT perfusion (CTP) in endovascular treatment selection for patients with large vessel occlusions (LVO). However, the relationship between CTP and collateral circulation is unclear in delayed time windows. We explored the relationship between CT Angiogram (CTA) collaterals and CTP parameters in delayed time windows (6-24 hours).

MATERIALS AND METHODS

We utilized a single institutional, retrospective stroke registry of consecutive patients between May 2016 and May 2018 with anterior LVO with CTA and CTP imaging within 6-24 hours of stroke onset. We graded baseline collaterals on single phase CTA using modified Tan collateral score (0-3) and dichotomized into good (2-3) and poor (0-1) collaterals. We recorded automated CTP parameters, including estimated ischemic core (cerebral blood flow (CBF)<30%), penumbra (T_max>6 s), and mismatch ratio. We used Mann-Whitney test and linear regression to assess associations.

RESULTS

We included 48 patients with median age of 62 years (IQR= 52-72), median core of 17.5 mL (IQR=0-47), and median penumbra of 117.5 mL (IQR= 62-163.5). Patients with good collaterals had smaller median core (0 mL, IQR=0-12 mL vs. 40.5 mL, IQR=15-60 mL) (p < 0.001), smaller median penumbra (83.5 mL, IQR=43-135 mL vs. 142.5 mL, IQR=77-190 mL) (p = 0.04), larger median mismatch ratio (13.7, IQR=5.7-58.0 vs. 3.1, IQR=2.1-5.0) (p < 0.001), and lower median hypoperfusion intensity ratio (0.23, IQR=0-0.44 vs. 0.52, IQR=0.45-0.63) (p < 0.001) than patients with poor collaterals.

CONCLUSIONS

In delayed time window LVO patients, good CTA collaterals are significantly associated with smaller CTP core, smaller penumbra, larger mismatch ratio, and lower hypoperfusion intensity ratio. CTA collateral assessment could be a potential valuable surrogate to perfusion imaging, particularly in stroke centers where CTP is unavailable.

Excessive White Matter Hyperintensity Increases Susceptibility to Poor Functional Outcomes After Acute Ischemic Stroke

Objective: To personalize the prognostication of post-stroke outcome using MRI-detected cerebrovascular pathology, we sought to investigate the association between the excessive white matter hyperintensity (WMH) burden unaccounted for by the traditional stroke risk profile of individual patients and their long-term functional outcomes after a stroke. Methods: We included 890 patients who survived after an acute ischemic stroke from the MRI-Genetics Interface Exploration (MRI-GENIE) study, for whom data on vascular risk factors (VRFs), including age, sex, atrial fibrillation, diabetes mellitus, hypertension, coronary artery disease, smoking, prior stroke history, as well as acute stroke severity, 3- to-6-month modified Rankin Scale score (mRS), WMH, and brain volumes, were available. We defined the unaccounted WMH (uWMH) burden via modeling of expected WMH burden based on the VRF profile of each individual patient. The association of uWMH and mRS score was analyzed by linear regression analysis. The odds ratios of patients who achieved full functional independence (mRS < 2) in between trichotomized uWMH burden groups were calculated by pair-wise comparisons. Results: The expected WMH volume was estimated with respect to known VRFs. The uWMH burden was associated with a long-term functional outcome (β = 0.104, p < 0.01). Excessive uWMH burden significantly reduced the odds of achieving full functional independence after a stroke compared to the low and average uWMH burden [OR = 0.4, 95% CI: (0.25, 0.63), p < 0.01 and OR = 0.61, 95% CI: (0.42, 0.87), p < 0.01, respectively]. Conclusion: The excessive amount of uWMH burden unaccounted for by the traditional VRF profile was associated with worse post-stroke functional outcomes. Further studies are needed to evaluate a lifetime brain injury reflected in WMH unrelated to the VRF profile of a patient as an important factor for stroke recovery and a plausible indicator of brain health.

MRI Radiomic Signature of White Matter Hyperintensities Is Associated With Clinical Phenotypes

OBJECTIVE

Neuroimaging measurements of brain structural integrity are thought to be surrogates for brain health, but precise assessments require dedicated advanced image acquisitions. By means of quantitatively describing conventional images, radiomic analyses hold potential for evaluating brain health. We sought to: (1) evaluate radiomics to assess brain structural integrity by predicting white matter hyperintensities burdens (WMH) and (2) uncover associations between predictive radiomic features and clinical phenotypes.

METHODS

We analyzed a multi-site cohort of 4,163 acute ischemic strokes (AIS) patients with T2-FLAIR MR images with total brain and WMH segmentations. Radiomic features were extracted from normal-appearing brain tissue (brain mask-WMH mask). Radiomics-based prediction of personalized WMH burden was done using ElasticNet linear regression. We built a radiomic signature of WMH with stable selected features predictive of WMH burden and then related this signature to clinical variables using canonical correlation analysis (CCA).

RESULTS

Radiomic features were predictive of WMH burden (R 2 = 0.855 ± 0.011). Seven pairs of canonical variates (CV) significantly correlated the radiomics signature of WMH and clinical traits with respective canonical correlations of 0.81, 0.65, 0.42, 0.24, 0.20, 0.15, and 0.15 (FDR-corrected p-values CV 1 - 6 < 0.001, p-value CV 7 = 0.012). The clinical CV1 was mainly influenced by age, CV2 by sex, CV3 by history of smoking and diabetes, CV4 by hypertension, CV5 by atrial fibrillation (AF) and diabetes, CV6 by coronary artery disease (CAD), and CV7 by CAD and diabetes.

CONCLUSION

Radiomics extracted from T2-FLAIR images of AIS patients capture microstructural damage of the cerebral parenchyma and correlate with clinical phenotypes, suggesting different radiographical textural abnormalities per cardiovascular risk profile. Further research could evaluate radiomics to predict the progression of WMH and for the follow-up of stroke patients' brain health.

Acute Stroke Imaging Research Roadmap IV: Imaging Selection and Outcomes in Acute Stroke Clinical Trials and Practice

BACKGROUND AND PURPOSE

The Stroke Treatment Academic Industry Roundtable (STAIR) sponsored an imaging session and workshop during the Stroke Treatment Academic Industry Roundtable XI via webinar on October 1 to 2, 2020, to develop consensus recommendations, particularly regarding optimal imaging at primary stroke centers.

METHODS

This forum brought together stroke neurologists, neuroradiologists, neuroimaging research scientists, members of the National Institute of Neurological Disorders and Stroke, industry representatives, and members of the US Food and Drug Administration to discuss imaging priorities in the light of developments in reperfusion therapies, particularly in an extended time window, and reinvigorated interest in brain cytoprotection trials.

RESULTS

The imaging session summarized and compared the imaging components of recent acute stroke trials and debated the optimal imaging strategy at primary stroke centers. The imaging workshop developed consensus recommendations for optimizing the acquisition, analysis, and interpretation of computed tomography and magnetic resonance acute stroke imaging, and also recommendations on imaging strategies for primary stroke centers.

CONCLUSIONS

Recent positive acute stroke clinical trials have extended the treatment window for reperfusion therapies using imaging selection. Achieving rapid and high-quality stroke imaging is therefore critical at both primary and comprehensive stroke centers. Recommendations for enhancing stroke imaging research are provided.

Outcome after acute ischemic stroke is linked to sex-specific lesion patterns

Acute ischemic stroke affects men and women differently. In particular, women are often reported to experience higher acute stroke severity than men. We derived a low-dimensional representation of anatomical stroke lesions and designed a Bayesian hierarchical modeling framework tailored to estimate possible sex differences in lesion patterns linked to acute stroke severity (National Institute of Health Stroke Scale). This framework was developed in 555 patients (38% female). Findings were validated in an independent cohort (n = 503, 41% female). Here, we show brain lesions in regions subserving motor and language functions help explain stroke severity in both men and women, however more widespread lesion patterns are relevant in female patients. Higher stroke severity in women, but not men, is associated with left hemisphere lesions in the vicinity of the posterior circulation. Our results suggest there are sex-specific functional cerebral asymmetries that may be important for future investigations of sex-stratified approaches to management of acute ischemic stroke.

Brain and Lung Imaging Correlation in Patients with COVID-19: Could the Severity of Lung Disease Reflect the Prevalence of Acute Abnormalities on Neuroimaging? A Global Multicenter Observational Study

PURPOSE

Our aim was to study the association between abnormal findings on chest and brain imaging in patients with coronavirus disease 2019 (COVID-19) and neurologic symptoms.

MATERIALS AND METHODS

In this retrospective, international multicenter study, we reviewed the electronic medical records and imaging of hospitalized patients with COVID-19 from March 3, 2020, to June 25, 2020. Our inclusion criteria were patients diagnosed with Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) infection with acute neurologic manifestations and available chest CT and brain imaging. The 5 lobes of the lungs were individually scored on a scale of 0-5 (0 corresponded to no involvement and 5 corresponded to >75% involvement). A CT lung severity score was determined as the sum of lung involvement, ranging from 0 (no involvement) to 25 (maximum involvement).

RESULTS

A total of 135 patients met the inclusion criteria with 132 brain CT, 36 brain MR imaging, 7 MRA of the head and neck, and 135 chest CT studies. Compared with 86 (64%) patients without acute abnormal findings on neuroimaging, 49 (36%) patients with these findings had a significantly higher mean CT lung severity score (9.9 versus 5.8, P < .001). These patients were more likely to present with ischemic stroke (40 [82%] versus 11 [13%], P < .0001) and were more likely to have either ground-glass opacities or consolidation (46 [94%] versus 73 [84%], P = .01) in the lungs. A threshold of the CT lung severity score of >8 was found to be 74% sensitive and 65% specific for acute abnormal findings on neuroimaging. The neuroimaging hallmarks of these patients were acute ischemic infarct (28%), intracranial hemorrhage (10%) including microhemorrhages (19%), and leukoencephalopathy with and/or without restricted diffusion (11%). The predominant CT chest findings were peripheral ground-glass opacities with or without consolidation.

CONCLUSIONS

The CT lung disease severity score may be predictive of acute abnormalities on neuroimaging in patients with COVID-19 with neurologic manifestations. This can be used as a predictive tool in patient management to improve clinical outcome.

Correlation of Alberta Stroke Program Early Computed Tomography Score With Computed Tomography Perfusion Core in Large Vessel Occlusion in Delayed Time Windows

BACKGROUND AND PURPOSE

The Alberta Stroke Program Early Computed Tomography (CT) Score (ASPECTS) and CT perfusion (CTP) are commonly used to predict the ischemic core in acute ischemic strokes. CT angiography source images (CTA-SI) can also provide additional information to identify the extent of ischemia. Our objective was to investigate the correlation of noncontrast CT (NCCT) ASPECTS and CTA-SI ASPECTS with CTP core volumes.

METHODS

We utilized a single institutional, retrospective registry of consecutive patients with acute ischemic stroke with large vessel occlusion between May 2016 and May 2018. We graded ASPECTS both on baseline NCCT and CTA-SI and measured CTP core using automated RAPID software (cerebral blood flow <30%). We used Spearman's correlation coefficients to evaluate the correlation between continuous variables.

RESULTS

A total of 52 patients fit the inclusion criteria of large vessel occlusion in 6 to 24 hours and baseline imaging work up of NCCT, CTA, and CTP. The median age was 63 (interquartile range=53.5-75) and 38.46% were female. The median NCCT ASPECTS was 7 (interquartile range=6-9), CTA-SI ASPECTS was 5 (interquartile range=4-7), and CTP core was 14.5 mL (interquartile range=0-46 mL). There was a moderate correlation between NCCT ASPECTS and CTP core (r_s=-0.55, P<0.0001) and between CTA-SI ASPECTS and CTP core (r_s=-0.50, P=0.0002). The optimal NCCT ASPECTS cutoff score to detect CTP core ≤70 mL was ≥6 (sensitivity, 0.84; specificity, 0.57; positive predictive value, 0.93; negative predictive value, 0.36) and the optimal CTA-SI ASPECTS was ≥5 (sensitivity, 0.76; specificity, 0.71; positive predictive value, 0.94; negative predictive value, 0.31).

CONCLUSIONS

There was a moderate correlation between NCCT and CTA-SI ASPECTS in predicting CTP defined ischemic core in delayed time windows. Further studies are needed to determine if NCCT and CTA imaging could be used for image-based patient selection when CTP imaging is not available.

Imaging of Neurologic Disease in Hospitalized Patients with COVID-19: An Italian Multicenter Retrospective Observational Study

Of 725 consecutive hospitalized patients with coronavirus disease 2019, 108 (15%) had acute neurologic symptoms necessitating neurologic imaging.

Recover Wisely From COVID-19: Responsible Resumption of Nonurgent Radiology Services

Rationale and Objectives

Following state and institutional guidelines, our Radiology department launched the “Recover Wisely” for all nonurgent radiology care on May 4, 2020. Our objective is to report our practice implementation and experience of COVID-19 recovery during the resumption of routine imaging at a tertiary academic medical center.

Materials and Methods

We used the SQUIRE 2.0 guidelines for this practice implementation. Recover Wisely focused on a data driven, strategic rescheduling and redesigning patient flow process. We used scheduling simulations and meticulous monitoring and control of outpatient medical imaging volumes to achieve a linear restoration to our pre-COVID imaging studies. We had a tiered plan to address the backlog of rescheduled patients with gradual opening of our imaging facilities, while maintaining broad communication with our patients and referring clinicians.

Results

Recover Wisely followed our anticipated linear modeling. Considering the last 10 weeks in the recovery, outpatient growth was linear with an increase of approximately 172 cases per week, (R² =0.97). We achieved an overall recovery of 102% in week 10, as compared to average weekly pre-COVID outpatient volumes. The modalities recovered as follows in outpatient volumes: CT (113%), MRI (101%), nuclear medicine including PET (138%), mammograms (97%), ultrasound (99%) and interventional radiology (106%). When compared to identical 2019 calendar weeks (May 4, 2020–July 10, 2020), the total 2020 radiology volume was 11% reduced from the 2019 volume. The reduction in total weighted relative value units was 8% in this time period, as compared to 2019.

Conclusion

Our department utilized a data-driven, team approach based on our guiding principles to “Recover Wisely.” We created and implemented a methodology that achieved a linear increase in outpatient studies over a 10-week recovery period.

Prognostic Value of Spreading Depolarizations in Patients With Severe Traumatic Brain Injury

Importance

Advances in treatment of traumatic brain injury are hindered by the inability to monitor pathological mechanisms in individual patients for targeted neuroprotective treatment. Spreading depolarizations, a mechanism of lesion development in animal models, are a novel candidate for clinical monitoring in patients with brain trauma who need surgery.

Objective

To test the null hypothesis that spreading depolarizations are not associated with worse neurologic outcomes.

Design, Setting, and Participants

This prospective, observational, multicenter cohort study was conducted from February 2009 to August 2013 in 5 level 1 trauma centers. Consecutive patients who required neurological surgery for treatment of acute brain trauma and for whom research consent could be obtained were enrolled; participants were excluded because of technical problems in data quality, patient withdrawal, or loss to follow-up. Primary statistical analysis took place from April to December 2018. Evaluators of outcome assessments were blinded to other measures.

Interventions

A 6-contact electrode strip was placed on the brain surface during surgery for continuous electrocorticography during intensive care.

Main Outcomes and Measures

Electrocorticography was scored for depolarizations, following international consensus procedures. Six-month outcomes were assessed by the Glasgow Outcome Scale-Extended score.

Results

A total of 157 patients were initially enrolled; 19 were subsequently excluded. The 138 remaining patients (104 men [75%]; median [interquartile range] age, 45 [29-64] years) underwent a median (interquartile range) of 75.5 (42.2-117.1) hours of electrocorticography. A total of 2837 spreading depolarizations occurred in 83 of 138 patients (60.1% incidence) who, compared with patients who did not have spreading depolarizations, had lower prehospital systolic blood pressure levels (mean [SD], 133 [31] mm Hg vs 146 [33] mm Hg; P = .03), more traumatic subarachnoid hemorrhage (depolarization incidences of 17 of 37 [46%], 18 of 32 [56%], 22 of 33 [67%], and 23 of 30 patients [77%] for Morris-Marshall Grades 0, 1, 2, and 3/4, respectively; P = .047), and worse radiographic pathology (in 38 of 73 patients [52%] and 42 of 60 patients [70%] for Rotterdam Scores 2-4 vs 5-6, respectively; P = .04). Of patients with depolarizations, 32 of 83 (39%) had only sporadic events that induced cortical spreading depression of spontaneous electrical activity, whereas 51 of 83 patients (61%) exhibited temporal clusters of depolarizations (≥3 in a 2-hour span). Nearly half of those with clusters (23 of 51 [45%]) also had depolarizations in an electrically silent area of the cortex (isoelectric spreading depolarization). Patients with clusters did not improve in motor neurologic examinations from presurgery to postelectrocorticography, while other patients did improve. In multivariate ordinal regression adjusting for baseline prognostic variables, the occurrence of depolarization clusters had an odds ratio of 2.29 (95% CI, 1.13-4.65; P = .02) for worse outcomes.

Conclusions and Relevance

In this cohort study of patients with acute brain trauma, spreading depolarizations were predominant but heterogeneous and independently associated with poor neurologic recovery. Monitoring the occurrence of spreading depolarizations may identify patients most likely to benefit from targeted management strategies.

Rescheduling Nonurgent Care in Radiology: Implementation During the Coronavirus Disease 2019 (COVID-19) Pandemic

OBJECTIVE

To meet hospital preparedness for the coronavirus disease 2019 pandemic, the Centers for Disease Control and Prevention and ACR recommended delay of all nonemergent tests and elective procedures. The purpose of this article is to report our experience for rescheduling nonemergent imaging and procedures during the pandemic at our tertiary academic institution.

METHODS

We rescheduled the nonemergent imaging and procedures in our hospitals and outpatient centers from March 16 to May 4, 2020. We created a tiered priority system to reschedule patients for whom imaging could be delayed with minimal clinical impact. The radiologists performed detailed chart reviews for decision making. We conducted daily virtual huddles with discussion of rescheduling strategies and issue tracking.

RESULTS

Using a snapshot during the rescheduling period, there was a 53.4% decrease in imaging volume during the period of March 16 to April 15, 2020, compared with the same time period in 2019. The total number of imaging studies decreased from 38,369 in 2019 to 17,891 in 2020 during this period. Although we saw the largest reduction in outpatient imaging (72.3%), there was also a significant decrease in inpatient (40.5%) and emergency department (48.9%) imaging volumes.

DISCUSSION

The use of multiple communication channels was critical in relaying the information to all our stakeholders, patients, referring physicians, and the radiology workforce. Teamwork, quick adoption, and adaptation of changing strategies was important given the fluidity of the situation.

Brain Volume: An Important Determinant of Functional Outcome After Acute Ischemic Stroke

OBJECTIVE

To determine whether brain volume is associated with functional outcome after acute ischemic stroke (AIS).

PATIENTS AND METHODS

This study was conducted between July 1, 2014, and March 16, 2019. We analyzed cross-sectional data of the multisite, international hospital-based MRI-Genetics Interface Exploration study with clinical brain magnetic resonance imaging obtained on admission for index stroke and functional outcome assessment. Poststroke outcome was determined using the modified Rankin Scale score (0-6; 0 = asymptomatic; 6 = death) recorded between 60 and 190 days after stroke. Demographic characteristics and other clinical variables including acute stroke severity (measured as National Institutes of Health Stroke Scale score), vascular risk factors, and etiologic stroke subtypes (Causative Classification of Stroke system) were recorded during index admission.

RESULTS

Utilizing the data from 912 patients with AIS (mean ± SD age, 65.3±14.5 years; male, 532 [58.3%]; history of smoking, 519 [56.9%]; hypertension, 595 [65.2%]) in a generalized linear model, brain volume (per 155.1 cm³) was associated with age (β -0.3 [per 14.4 years]), male sex (β 1.0), and prior stroke (β -0.2). In the multivariable outcome model, brain volume was an independent predictor of modified Rankin Scale score (β -0.233), with reduced odds of worse long-term functional outcomes (odds ratio, 0.8; 95% CI, 0.7-0.9) in those with larger brain volumes.

CONCLUSION

Larger brain volume quantified on clinical magnetic resonance imaging of patients with AIS at the time of stroke purports a protective mechanism. The role of brain volume as a prognostic, protective biomarker has the potential to forge new areas of research and advance current knowledge of the mechanisms of poststroke recovery.

The Impact of the COVID-19 Pandemic on the Radiology Research Enterprise: Radiology Scientific Expert Panel

The current COVID-19 crisis continues to grow and has resulted in marked changes to clinical operations. In parallel with clinical preparedness, universities have shut down the majority of scientific research activities. Radiology researchers are currently grappling with these challenges that will continue to affect current and future imaging research. The purpose of this article is to describe the collective experiences of a diverse international group of academic radiology research programs in managing their response to the COVID-19 pandemic. The acute response at six distinct institutions will first be described, exploring common themes, challenges, priorities, and practices. This will be followed by reflections about the future of radiology research in the wake of the COVID-19 pandemic.

Abstract WP77: Final Infarct Volume May Predict Functional Outcome After Mild, Nondisabling Ischemic Stroke: Results From the PRISMS Trial

Introduction: In patients with acute cerebral ischemia (ACI) within 3h of onset with mild deficit judged as nondisabling at presentation, up to 20% experience poor functional outcome at 90 days. We tested the hypothesis that the presence of infarction at 24h would independently predict worse outcome at 3 months, and also explored the role of final infarct volume (FIV) on outcomes.

Methods: The phase 3b, randomized PRISMS trial compared intravenous alteplase to aspirin for mild (NIHSS 0-5), nondisabling stroke at <3 h from onset. In a prespecified analysis, we included patients with 24h MRI performed and excluded acute cerebral ischemia mimics. Central readers assessed Day 24h MRIs for acute infarct, chronic infarcts, and white matter hyperintensity (WMH) burden; FIV and WMH volumes were measured quantitatively using semi-automated software. The primary outcome was 3-month EQ5D scores, a measure of QOL, and the secondary outcome was modified Rankin Scale (mRS) scores, a measure of disability. Multivariable linear regression and proportional odds cumulative logit models were used to evaluate the association between (1) acute infarction presence and (2) FIV on the primary and secondary outcomes, respectively, adjusting for relevant covariates (Table 1).

Results: Of 313 patients enrolled, 273 had a final diagnosis of ACI and 212/273 (77%) had 24h MRI scans. Acute infarcts were present In 109 (51%), and median FIV was 1.20 mL (IQR 0.57-2.50). No association between presence of acute infarcts and 3-month EQ5D (p=0.84) or mRS (p=0.17) scores was observed (Table 1A). No association between FIV and EQ5D scores (p=0.31) was observed as well, but FIV was strongly associated with mRS scores (OR 1.11, 95% CI 1.04-1.18, p<0.001), in adjusted models (Table 1B).

Conclusions: Among patients presenting with mild, nondisabling ACI, FIV appears to be associated with worse functional outcome. Since this was a post-hoc analysis, this hypothesis requires further prospective study.

Race/ethnicity influences outcomes in young adults with supratentorial intracerebral hemorrhage

OBJECTIVES

We investigated the predictors of functional outcome in young patients enrolled in a multiethnic study of intracerebral hemorrhage (ICH).

METHODS

The Ethnic/Racial Variations in Intracerebral Hemorrhage (ERICH) study is a prospective multicenter study of ICH among adult (age ≥18 years) non-Hispanic white, non-Hispanic black, and Hispanic participants. The study recruited 1,000 participants per racial/ethnic group. The present study utilized the subset of ERICH participants aged <50 years with supratentorial ICH. Functional outcome was ascertained using the modified Rankin Scale (mRS) at 3 months. Logistic regression was used to identify factors associated with poor outcome (mRS 4-6), and analyses were compared by race/ethnicity to identify differences across these groups.

RESULTS

Of the 3,000 patients with ICH enrolled in ERICH, 418 were studied (mean age 43 years, 69% male), of whom 48 (12%) were white, 173 (41%) were black, and 197 (47%) were Hispanic. For supratentorial ICH, black participants (odds ratio [OR], 0.42; p = 0.046) and Hispanic participants (OR, 0.34; p = 0.01) had better outcomes than white participants after adjustment for other factors associated with poor outcome: age, baseline disability, admission blood pressure, admission Glasgow Coma Scale score, ICH volume, deep ICH location, and intraventricular extension.

CONCLUSIONS

In young patients with supratentorial ICH, black and Hispanic race/ethnicity is associated with better functional outcomes, compared with white race. Additional studies are needed to identify the biological and social mediators of this association.

Automated CT perfusion imaging for acute ischemic stroke: Pearls and pitfalls for real-world use

Recent positive trials have thrust acute cerebral perfusion imaging into the routine evaluation of acute ischemic stroke. Updated guidelines state that in patients with anterior circulation large vessel occlusions presenting beyond 6 hours from time last known well, advanced imaging selection including perfusion-based selection is necessary. Centers that receive patients with acute stroke must now have the capability to perform and interpret CT or magnetic resonance perfusion imaging or provide rapid transfer to centers with the capability of selecting patients for a highly impactful endovascular therapy, particularly in delayed time windows. Many stroke centers are quickly incorporating the use of automated perfusion processing software to interpret perfusion raw data. As CT perfusion (CTP) is being assimilated in real-world clinical practice, it is essential to understand the basics of perfusion acquisition, quantification, and interpretation. It is equally important to recognize the common technical and clinical diagnostic challenges of automated CTP including ischemic core and penumbral misclassifications that could result in underestimation or overestimation of the core and penumbra volumes. This review highlights the pitfalls of automated CTP along with practical pearls to address the common challenges. This is particularly tailored to aid the acute stroke clinician who must interpret automated perfusion studies in an emergency setting to make time-dependent treatment decisions for patients with acute ischemic stroke.

Collateral Clock Is More Important Than Time Clock for Tissue Fate

Background and Purpose- Although perfusion abnormality is an increasingly important therapeutic target, the natural history of tissue at risk without reperfusion treatment is understudied. Our objective was to determine how time affects penumbral salvage and infarct growth in untreated acute ischemic stroke patients and whether collateral status affects this relationship. Methods- We used a prospectively collected, multicenter acute stroke registry to assess acute stroke patients who were not treated with intravenous thrombolysis or endovascular treatment. We analyzed baseline computed tomography angiogram and computed tomography perfusion within 24 hours of stroke onset along with follow-up imaging and assessed time from stroke onset to baseline imaging, ASPECTS (Alberta Stroke Program Early CT Score), vessel occlusion, collaterals, ischemic core, and penumbra. Penumbral salvage and infarct growth were calculated. Correlations between time and penumbral salvage and infarct growth were evaluated with Spearman correlation. Penumbral salvage and infarct growth were compared between subjects with good versus poor collateral status using the Wilcoxon rank-sum test. Clinical and imaging factors affecting penumbral salvage and infarct growth were evaluated by linear regression. Results- Among 94 untreated stroke patients eligible for this analysis, the mean age was 65 years, median National Institutes of Health Stroke Scale score was 13, and median (range) time from stroke onset to baseline imaging was 2.9 (0.4-23) hours. There was no correlation between time and salvaged penumbra ( r=0.06; P=0.56) or infarct growth ( r=-0.05; P=0.61). Infarct growth was higher among those with poor collaterals versus those with good collaterals (median, 52.3 versus 0.9 cm³; P<0.01). Penumbral salvage was lower among those with poor collaterals compared with those with good collaterals (poor, 0 [0-0]; good, 5.9 cm³ [0-29.4]; P<0.01). Multivariable linear regression demonstrated that collaterals, but not time, were significantly associated with infarct growth and penumbral salvage. Conclusions- In this natural history study, penumbral salvage and infarct growth were less time dependent and more a measure of collateral flow.

Big Data Approaches to Phenotyping Acute Ischemic Stroke Using Automated Lesion Segmentation of Multi-Center Magnetic Resonance Imaging Data

Background and Purpose- We evaluated deep learning algorithms' segmentation of acute ischemic lesions on heterogeneous multi-center clinical diffusion-weighted magnetic resonance imaging (MRI) data sets and explored the potential role of this tool for phenotyping acute ischemic stroke. Methods- Ischemic stroke data sets from the MRI-GENIE (MRI-Genetics Interface Exploration) repository consisting of 12 international genetic research centers were retrospectively analyzed using an automated deep learning segmentation algorithm consisting of an ensemble of 3-dimensional convolutional neural networks. Three ensembles were trained using data from the following: (1) 267 patients from an independent single-center cohort, (2) 267 patients from MRI-GENIE, and (3) mixture of (1) and (2). The algorithms' performances were compared against manual outlines from a separate 383 patient subset from MRI-GENIE. Univariable and multivariable logistic regression with respect to demographics, stroke subtypes, and vascular risk factors were performed to identify phenotypes associated with large acute diffusion-weighted MRI volumes and greater stroke severity in 2770 MRI-GENIE patients. Stroke topography was investigated. Results- The ensemble consisting of a mixture of MRI-GENIE and single-center convolutional neural networks performed best. Subset analysis comparing automated and manual lesion volumes in 383 patients found excellent correlation (ρ=0.92; P<0.0001). Median (interquartile range) diffusion-weighted MRI lesion volumes from 2770 patients were 3.7 cm3 (0.9-16.6 cm3). Patients with small artery occlusion stroke subtype had smaller lesion volumes ( P<0.0001) and different topography compared with other stroke subtypes. Conclusions- Automated accurate clinical diffusion-weighted MRI lesion segmentation using deep learning algorithms trained with multi-center and diverse data is feasible. Both lesion volume and topography can provide insight into stroke subtypes with sufficient sample size from big heterogeneous multi-center clinical imaging phenotype data sets.

White matter hyperintensity quantification in large-scale clinical acute ischemic stroke cohorts - The MRI-GENIE study

White matter hyperintensity (WMH) burden is a critically important cerebrovascular phenotype linked to prediction of diagnosis and prognosis of diseases, such as acute ischemic stroke (AIS). However, current approaches to its quantification on clinical MRI often rely on time intensive manual delineation of the disease on T2 fluid attenuated inverse recovery (FLAIR), which hinders high-throughput analyses such as genetic discovery.

In this work, we present a fully automated pipeline for quantification of WMH in clinical large-scale studies of AIS. The pipeline incorporates automated brain extraction, intensity normalization and WMH segmentation using spatial priors. We first propose a brain extraction algorithm based on a fully convolutional deep learning architecture, specifically designed for clinical FLAIR images. We demonstrate that our method for brain extraction outperforms two commonly used and publicly available methods on clinical quality images in a set of 144 subject scans across 12 acquisition centers, based on dice coefficient (median 0.95; inter-quartile range 0.94–0.95; p < 0.01) and Pearson correlation of total brain volume (r = 0.90). Subsequently, we apply it to the large-scale clinical multi-site MRI-GENIE study (N = 2783) and identify a decrease in total brain volume of −2.4 cc/year. Additionally, we show that the resulting total brain volumes can successfully be used for quality control of image preprocessing.

Finally, we obtain WMH volumes by building on an existing automatic WMH segmentation algorithm that delineates and distinguishes between different cerebrovascular pathologies. The learning method mimics expert knowledge of the spatial distribution of the WMH burden using a convolutional auto-encoder. This enables successful computation of WMH volumes of 2533 clinical AIS patients. We utilize these results to demonstrate the increase of WMH burden with age (0.950 cc/year) and show that single site estimates can be biased by the number of subjects recruited.

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Fully automated high-throughput white matter hyperintensity segmentation pipeline.

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Methodology designed for and applied to international clinical multi-site data.

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Calculation of disease burden in 2533 acute ischemic stroke patients.

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Total brain volume change with age (−2.4 cc/year) used in automated quality control.

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Increase of white matter hyperintensity burden of 0.95 cc/year.

Diagnostic accuracy of MRI texture analysis for grading gliomas

PURPOSE

Texture analysis (TA) can quantify variations in surface intensity or patterns, including some that are imperceptible to the human visual system. The purpose of this study was to determine the diagnostic accuracy of radiomic based filtration-histogram TA to differentiate high-grade from low-grade gliomas by assessing tumor heterogeneity.

METHODS

Patients with a histopathological diagnosis of glioma and preoperative 3T MRI imaging were included in this retrospective study. A region of interest was manually delineated on post-contrast T1 images. TA was performed using commercially available research software. The histogram parameters including mean, standard deviation, entropy, mean of the positive pixels, skewness, and kurtosis were analyzed at spatial scaling factors ranging from 0 to 6 mm. The parameters were correlated with WHO glioma grade using Spearman correlation. Areas under the curve (AUC) were calculated using ROC curve analysis to distinguish tumor grades.

RESULTS

Of a total of 94 patients, 14 had low-grade gliomas and 80 had high-grade gliomas. Mean, SD, MPP, entropy and kurtosis each showed significant differences between glioma grades for different spatial scaling filters. Low and high-grade gliomas were best-discriminated using mean of 2 mm fine texture scale, with a sensitivity and specificity of 93% and 86% (AUC of 0.90).

CONCLUSIONS

Quantitative measurement of heterogeneity using TA can discriminate high versus low-grade gliomas. Radiomic data of texture features can provide complementary diagnostic information for gliomas.