Comparison of CT Perfusion Software Packages for Thrombectomy Eligibility.

INTRODUCTION: Computed tomography perfusion (CTP) has played an important role in patient selection for mechanical thrombectomy (MT) in acute ischemic stroke. We aimed to investigate the agreement between perfusion parametric maps of 3 software packages - RAPID (RapidAI-IschemaView), Viz CTP(Viz.ai), and e-CTP(Brainomix) - in estimating baseline ischemic core volumes of near completely/completely reperfused patients. METHODS: We retrospectively reviewed a prospectively maintained MT database to identify patients with anterior circulation large vessel occlusion strokes (LVOS) involving the internal carotid artery or middle cerebral artery M1-segment and interpretable CTP maps treated during September 2018 to November 2019. A subset of patients with near-complete/complete reperfusion (expanded thrombolysis in cerebral infarction [eTICI] 2c-3) was used to compare the pre-procedural prediction of final infarct volumes. RESULTS: In this analysis of 242 patients with LVOS, RAPID and Viz CTP relative cerebral blood flow (rCBF) < 30% values had substantial agreement (ρ = 0.767 [95% confidence interval [CI] = 0.71-0.81]) as well as for RAPID and e-CTP (ρ = 0.668 [95% CI = 0.61-0.71]). Excellent agreement was seen for time to maximum of the residue function (Tmax ) > 6 seconds between RAPID and Viz CTP (ρ = 0.811 [95% CI = 0.76-0.84]) and substantial for RAPID and e-CTP (ρ = 0.749 [95% CI = 0.69-0.79]). Final infarct volume (FIV) prediction (n = 136) was substantial in all 3 packages (RAPID ρ = 0.744; Viz CTP ρ = 0.711; and e-CTP ρ = 0.600). CONCLUSION: Perfusion parametric maps of the RAPID, Viz CTP, and e-CTP software have substantial agreement in predicting final infarct volume in near-completely/completely reperfused patients. ANN NEUROL 2023;94:848-855.

Optimization of collateral grading on computer tomography angiography.

BACKGROUND: As compared to single-phase CTA (sCTA), multi-phase CTA (mCTA) has been shown to more accurately estimate collateral flow in acute ischemic stroke (AIS). We sought to determine the characterization of poor collaterals across the three different phases of the mCTA. We also attempted to establish the optimal arterio-venous contrast timing parameters on sCTA that would prevent false positive reads of poor collateral status. METHODS: We retrospectively screened consecutive patients admitted for possible thrombectomy from February 2018 to June 2019. Only cases with intracranial internal carotid artery (ICA) or main trunk of the middle cerebral artery (MCA) occlusion and both baseline mCTA and CT Perfusion available were included. Mean Hounsfield units (HU) of torcula and torcula/patent ICA ratio were used for the arterio-venous timing analysis. RESULTS: Of the 105 patients included, 35 (34%) received IV-tPA treatment and 65 (61.9%) underwent mechanical thrombectomy. A total of 20 patients (19%) had poor collaterals on the third-phase CTA (ground-truth). The first-phase CTA often underestimated collateral score (37/105 [35%], p < 0.01), however there were no significant differences across the second- and third-phases (5/105[5%], p = 0.06. Venous opacification Youden's J point for identifying suboptimal sCTAs was found to be 207.9HU in the torcula (65% sensitivity,65% specificity) and 66.74% for torcula/patent ICA ratio (51% sensitivity,73% specificity). CONCLUSION: A dual-phase CTA is significantly similar to a mCTA assessment of collateral score and may be applied at community-based centers. Absolute or relative thresholds for torcula opacification may be used to identify poor bolus-scan timing thus preventing erroneous assumptions of poor collaterals on sCTA.

Acute Hemorrhagic Leukoencephalopathy Triggered by COVID-19 Infection.

Background: This study represents an additional case of a rare entity and complication of COVID-19. Purpose: To further describe COVID's association with acute hemorrhagic leukoencephalopathy (AHL), a variant of acute disseminated encephalomyelitis. Besides, subsequent neuropsychological evaluation is described. Methods: The present case report describes clinical, laboratory, radiological, and electroencephalographic characteristics of AHL triggered by COVID-19, in addition to outcomes in the neuropsychological findings. Results: Radiologic findings of demyelinating lesions in supratentorial white matter permeated by multiple hemorrhagic foci supported the diagnostic of AHL, reinforced by clinical improvement after corticosteroid therapy. Conclusions: There are few similar cases previously reported, and this case highlights the early diagnosis and prompt treatment looking forward to better outcomes in AHL. Further studies are needed to elucidate the involved pathophysiological mechanisms.

The Prognostic Value of Quantitative EEG in Patients Undergoing Mechanical Thrombectomy for Acute Ischemic Stroke.

PURPOSE: Previous work has shown that quantitative EEG measures correlate with the severity of ischemic stroke. This has not been systematically validated in patients with acute ischemic stroke who have undergone mechanical thrombectomy. METHODS: Data were collected from 73 patients who underwent mechanical thrombectomy and had a standard head set EEG performed during their hospital admission. For each patient, the global delta-alpha ratio (DAR) and its difference between the two hemispheres were calculated. Associations between the global and interhemispheric DAR difference with the patients' National Institutes of Health Stroke and Modified Rankin Scale scores at discharge and 3 months after thrombectomy were assessed. RESULTS: The interhemispheric DAR difference correlated with the National Institutes of Health Stroke scores at discharge (Spearman R = 0.41, P = 0.0008), National Institutes of Health Stroke scores at 3 months (Spearman R = 0.60, P = 0.02) and Modified Rankin Scale scores at 3 months (Spearman R = 0.27, P = 0.01). In contrast, the global DAR did not correlate significantly with any of these clinical outcomes when evaluated as continuous variables. In a multivariate logistic regression model, both the interhemispheric DAR difference (ß = 0.25, P = 0.03) and the infarct volume (ß = 0.02, P = 0.03) were independently predictive of good versus poor functional outcome (Modified Rankin Scale score ≤2 vs. >2) at 3 months. CONCLUSIONS: The quantitative EEG measure of interhemispheric slow relative to fast frequencies power asymmetry correlated with the discharge and 3-month National Institutes of Health Stroke and Modified Rankin Scale scores and provided added value to infarct volume in predicting functional outcome at 3 months. These data support the prognostic value of quantitative EEG in ischemic stroke patients who have undergone mechanical thrombectomy.

Ghost infarct core following endovascular reperfusion: A risk for computed tomography perfusion misguided selection in stroke.

BACKGROUND: Computed tomography perfusion (CTP) has been increasingly used for patient selection in mechanical thrombectomy for stroke. However, previous studies suggested that CTP might overestimate the infarct size. The term ghost infarct core (GIC) has been used to describe an overestimation of the final infarct volumes by pre-treatment CTP of >10 ml. AIM: We sought to study the frequency and predictors of GIC. METHODS: A prospectively collected mechanical thrombectomy database at a comprehensive stroke center between September 2010 and August 2020 was reviewed. Patients were included if they had a successful reperfusion (mTICI2b-3), a pre-procedure CTP, and final infarct volume measured on follow-up magnetic resonance imaging. Uni- and multivariable analyses were performed to identify predictors of GIC. RESULTS: Among 923 eligible patients (median [IQR] age, 64 [55-75] years; NIHSS, 16 [11-21]; onset to reperfusion time, 436.5 [286-744.5] min), GIC was identified in 77 (8.3%) of the overall patients and in 14% (47/335) of those reperfused within 6 h of symptom onset. The median overestimation volume was 23.2 [16.4-38.3] mL. GIC was associated with higher NIHSS score, larger areas of infarct core and tissue at risk on CTP, unfavorable collateral scores, and shorter times from onset to image acquisition and to reperfusion as compared to non-GIC. Patients with GIC had smaller median final infarct volumes (10.7 vs. 27.1 ml, p < 0.001), higher chances of functional independence (76.2% vs. 55.5%, adjusted odds ratio (aOR) 3.829, 95% CI [1.505-9.737], p = 0.005), lower disability (one-point-mRS improvement, aOR 1.761, 95% CI [1.044-2.981], p = 0.03), and lower mortality (6.3% vs. 15%, aOR 0.119, 95% CI [0.014-0.984], p = 0.048) at 90 days. On multivariable analysis, time from onset to reperfusion ≤6 h (OR 3.184, 95% CI [1.743-5.815], p < 0.001), poor collaterals (OR 2.688, 95% CI [1.466-4.931], p = 0.001), and higher NIHSS score (OR 1.060, 95% CI [1.010-1.113], p = 0.018) were independent predictors of GIC. CONCLUSION: GIC is a relatively common entity, particularly in patients with poor collateral status, higher baseline NIHSS score, and early presentation, and is associated with more favorable outcomes. Patients should not be excluded from reperfusion therapies on the sole basis of CTP findings, especially in the early window.

Noncontrast Computed Tomography e-Stroke Infarct Volume Is Similar to RAPID Computed Tomography Perfusion in Estimating Postreperfusion Infarct Volumes.

BACKGROUND AND PURPOSE: The e-Stroke Suite software (Brainomix, Oxford, United Kingdom) is a tool designed for the automated quantification of The Alberta Stroke Program Early CT Score and ischemic core volumes on noncontrast computed tomography (NCCT). We sought to compare the prediction of postreperfusion infarct volumes and the clinical outcomes across NCCT e-Stroke software versus RAPID (IschemaView, Menlo Park, CA) computed tomography perfusion measurements. METHODS: All consecutive patients with anterior circulation large vessel occlusion stroke presenting at a tertiary care center between September 2010 and November 2018 who had available baseline infarct volumes on both NCCT e-Stroke Suite software and RAPID CTP as well as final infarct volume (FIV) measurements and achieved complete reperfusion (modified Thrombolysis in Cerebral Infarction scale 2c-3) post-thrombectomy were included. The associations between estimated baseline ischemic core volumes and FIV as well as 90-day functional outcomes were assessed. RESULTS: Four hundred seventy-nine patients met inclusion criteria. Median age was 64 years (55-75), median e-Stroke and computed tomography perfusion ischemic core volumes were 38.4 (21.8-58) and 5 (0-17.7) mL, respectively, whereas median FIV was 22.2 (9.1-56.2) mL. The correlation between e-Stroke and CTP ischemic core volumes was moderate (R=0.44; P<0.001). Similarly, moderate correlations were observed between e-Stroke software ischemic core and FIV (R=0.52; P<0.001) and CTP core and FIV (R=0.43; P<0.001). Subgroup analysis showed that e-Stroke software and CTP performance was similar in the early and late (>6 hours) treatment windows. Multivariate analysis showed that both e-Stroke software NCCT baseline ischemic core volume (adjusted odds ratio, 0.98 [95% CI, 0.97-0.99]) and RAPID CTP ischemic core volume (adjusted odds ratio, 0.98 [95% CI, 0.97-0.99]) were independently and comparably associated with good outcome (modified Rankin Scale score of 0-2) at 90 days. CONCLUSIONS: NCCT e-Stroke Suite software performed similarly to RAPID CTP in assessing postreperfusion FIV and functional outcomes for both early- and late-presenting patients. NCCT e-Stroke volumes seems to represent a viable alternative in centers where access to advanced imaging is limited. Moreover, the future development of fusion maps of NCCT and CTP ischemic core estimates may improve upon the current performance of these tools as applied in isolation.

Acute Neurological Deterioration in Large Vessel Occlusions and Mild Symptoms Managed Medically.

Background and Purpose- It is unclear which factors predict acute neurological deterioration in patients with large vessel occlusion and mild symptoms. We aim to evaluate the frequency, timing, and potential predictors of acute neurological deterioration ≥4 National Institutes of Health Stroke Scale (NIHSS) points in medically managed patients with large vessel occlusion and mild presentation. Methods- Single-center retrospective study of patients with consecutive minor stroke (defined as NIHSS score of ≤5 on presentation) and large vessel occlusion from January 2014 to December 2017. Primary outcome was acute neurological deterioration ≥4 NIHSS points during the hospitalization. Secondary outcomes included ΔNIHSS (defined as discharge minus admission NIHSS score). Results- Among 1133 patients with acute minor strokes, 122 (10.6%) had visible occlusions on computed tomography angiography/magnetic resonance angiography. Twenty-four (19.7%) patients had ≥4 points deterioration on NIHSS at a median of 3.6 (1-16) hours from arrival. No clinical or radiological predictors of acute neurological deterioration ≥4 NIHSS points were observed on multivariable analysis. Rescue endovascular thrombectomy was performed more often in the ones with acute neurological deterioration ≥4 NIHSS points compared with patients with no deterioration (54% versus 0%; P<0.001). Acute neurological deterioration ≥4 NIHSS points was associated with ΔNIHSS ≥4 points (33% versus 4.9%; P<0.01) and a trend toward lower independence rates at discharge (50% versus 70%; P=0.06) compared with the group with no deterioration. In patients with any degree of neurological worsening, patients who underwent rescue thrombectomy were more likely to be independent at discharge (73% versus 38%; P=0.02) and to have a favorable ΔNIHSS (-2 [-3 to 0] versus 0 [-1 to 6]; P=0.05) compared with the ones not offered rescue thrombectomy. Conclusions- Acute neurological deterioration ≥4 NIHSS points was observed in a fifth of patients with large vessel occlusion and mild symptoms, occurred very early in the hospital course, impacted functional outcomes, and could not be predicted by any of the studied clinical and radiological variables. Rescue thrombectomy was associated with improved clinical outcomes at discharge in patients with neurological deterioration.

Endovascular Stroke Treatment and Risk of Intracranial Hemorrhage in Anticoagulated Patients.

Background and Purpose- We aimed to determine the safety and mortality after mechanical thrombectomy in patients taking vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs). Methods- In a multicenter observational cohort study, we used multiple logistic regression analysis to evaluate associations of symptomatic intracranial hemorrhage (sICH) with VKA or DOAC prescription before thrombectomy as compared with no anticoagulation. The primary outcomes were the rate of sICH and all-cause mortality at 90 days, incorporating sensitivity analysis regarding confirmed therapeutic anticoagulation. Additionally, we performed a systematic review and meta-analysis of literature on this topic. Results- Altogether, 1932 patients were included (VKA, n=222; DOAC, n=98; no anticoagulation, n=1612); median age, 74 years (interquartile range, 62-82); 49.6% women. VKA prescription was associated with increased odds for sICH and mortality (adjusted odds ratio [aOR], 2.55 [95% CI, 1.35-4.84] and 1.64 [95% CI, 1.09-2.47]) as compared with the control group, whereas no association with DOAC intake was observed (aOR, 0.98 [95% CI, 0.29-3.35] and 1.35 [95% CI, 0.72-2.53]). Sensitivity analyses considering only patients within the confirmed therapeutic anticoagulation range did not alter the findings. A study-level meta-analysis incorporating data from 7462 patients (855 VKAs, 318 DOACs, and 6289 controls) from 15 observational cohorts corroborated these observations, yielding an increased rate of sICH in VKA patients (aOR, 1.62 [95% CI, 1.22-2.17]) but not in DOAC patients (aOR, 1.03 [95% CI, 0.60-1.80]). Conclusions- Patients taking VKA have an increased risk of sICH and mortality after mechanical thrombectomy. The lower risk of sICH associated with DOAC may also be noticeable in the acute setting. Improved selection might be advisable in VKA-treated patients. Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT03496064. Systematic Review and Meta-Analysis: CRD42019127464.

Prognostic importance of CT ASPECTS and CT perfusion measures of infarction in anterior emergent large vessel occlusions.

BACKGROUND: Age, neurologic deficits, core volume (CV), and clinical core or radiographic mismatch are considered in selection for endovascular therapy (ET) in anterior circulation emergent large vessel occlusion (aELVO). Semiquantitative CV estimation by Alberta Stroke Programme Early CT Score (CT ASPECTS) and quantitative CV estimation by CT perfusion (CTP) are both used in selection paradigms. OBJECTIVE: To compare the prognostic value of CTP CV with CT ASPECTS in aELVO. METHODS: Patients in an institutional endovascular registry who had aELVO, pre-ET National Institutes of Health Stroke Scale (NIHSS) score, non-contrast CT head and CTP imaging, and prospectively collected 3-month modified Rankin Scale (mRS) score were included. Age- and NIHSS-adjusted models, including either CT ASPECTS or CTP volumes (relative cerebral blood flow <30% of normal tissue, total hypoperfusion, and radiographic mismatch), were compared using receiver operator characteristic analyses. RESULTS: We included 508 patients with aELVO (60.8% M1 middle cerebral artery, 34% internal carotid artery, mean age 64.1±15.3 years, median baseline NIHSS score 16 (12-20), median baseline CT ASPECTS 8 (7-9), mean CV 16.7±24.8 mL). Age, pre-ET NIHSS, CT ASPECTS, CV, hypoperfusion, and perfusion imaging mismatch volumes were predictors of good outcome (mRS score 0-2). There were no differences in prognostic accuracies between reference (age, baseline NIHSS, CT ASPECTS; area under the curve (AUC)=0.76) and additional models incorporating combinations of age, NIHSS, and CTP metrics including CV, total hypoperfusion or mismatch volume (AUCs 0.72-0.75). Predicted outcomes from CT ASPECTS or CTP CV-based models had excellent agreement (R2=0.84, p<0.001). CONCLUSIONS: Incorporating CTP measures of core or penumbral volume, instead of CT ASPECTS, did not improve prognostication of 3-month outcomes, suggesting prognostic equivalence of CT ASPECTS and CTP CV.