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Background: In patients with acute ischemic stroke due to large vessel occlusion (AIS–LVO), development of extensive early ischemic brain edema is associated with poor functional outcomes, despite timely treatment. Robust cortical venous outflow (VO) profiles correlate with favorable tissue perfusion. We hypothesized that favorable VO profiles (VO+) correlate with a reduced early edema progression rate (EPR) and good functional outcomes. Methods: Multicenter, retrospective analysis to investigate AIS–LVO patients treated by mechanical thrombectomy between May 2013 and December 2020. Baseline computed tomography angiography (CTA) was used to determine VO using the cortical vein opacification score (COVES); VO+ was defined as COVES ⩾ 3 and unfavorable as COVES ⩽ 2. EPR was determined as the ratio of net water uptake (NWU) on baseline non-contrast CT and time from symptom onset to admission imaging. Multivariable regression analysis was performed to assess primary (EPR) and secondary outcome (good functional outcomes defined as 0–2 points on the modified Rankin scale). Results: A total of 728 patients were included. Primary outcome analysis showed VO+ (β: –0.03, SE : 0.009, p = 0.002), lower presentation National Institutes of Health Stroke Scale (NIHSS; β: 0.002, SE : 0.001, p = 0.002), and decreased time from onset to admission imaging (β: –0.00002, SE : 0.00004, p < 0.001) were independently associated with reduced EPR. VO+ also predicted good functional outcomes (odds ratio (OR): 5.07, 95% CI: 2.839–9.039, p < 0.001), while controlling for presentation NIHSS, time from onset to imaging, general vessel reperfusion, baseline Alberta Stroke Program Early CT Score, infarct core volume, EPR, and favorable arterial collaterals. Conclusions: Favorable VO profiles were associated with slower infarct edema progression and good long-term functional outcomes as well as better neurological status and ischemic brain alterations at admission. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Thrombi, or clots, often occlude proximal segments of the cerebral arterial circulation in acute ischemic stroke. Thromboembolic occlusion or thrombi superimposed on atherosclerotic plaque are the principal focus of acute stroke therapies such as thrombolysis or thrombectomy. We review the imaging characteristics of thrombi on multimodal computed tomography and magnetic resonance imaging, angiography, and ultrasonography, summarizing recent studies that facilitate therapeutic decision-making from these noninvasive studies. Information about the location, size, and imaging characteristics can be ascertained using these techniques. Imaging findings in relation to occlusive thrombus have been correlated with clot pathology, response to therapeutic interventions, and clinical outcome. Diagnostic evaluation of occlusive thrombi on noninvasive studies now constitutes an integral component of acute stroke management.

Collaterals 2016 (third International Symposium on Collaterals to the Brain) was a multidisciplinary scientific conference focused on collateral circulation in acute ischemic stroke. Decisive challenges include generalizability of optimal triage and selection paradigms based on collateral status for definitive treatment of acute ischemic stroke, rapid dissemination of expert methods, and the urgent need to leverage networking opportunities for stroke science related to the hemodynamics of collaterals. The collaterome, or individual capacity to offset ischemia in the brain, and determination of a favorable collateral profile have become pivotal factors in consideration of the precision medicine of stroke decisionmaking. The conference convened over 50 invited faculty from around the world to connect on-site participants at a state-of-the-art facility with remote audiences in more than 22 countries and regions. The 2½-day program was structured into 40-min sessions devoted to key issues in translating the collaterome in acute stroke therapy across the globe. This unique forum of expertise emphasized the timely impact of collaterals on a monumental scale, encouraging maximal participation, rapid diffusion and added value of a diverse networking resource. The meeting format established a model geographical framework and innovative videoconferencing platform for future scientific conferences. [ABSTRACT FROM AUTHOR]

Background: The steep, time-dependent loss of benefit from reperfusion in clinical trials is consistent with loss of penumbra over the early hours of ischemia, as observed in animal models. Human imaging studies, however, show persistent penumbra for up to 48 h.We investigated core and penumbra volumes and collateral status in relation to time after stroke onset within the first 6 h. Methods: Using data from three multimodal computer tomography-based studies in acute ischemic stroke patients <6 h after onset, we measured core and penumbra volumes, collateral status, and target mismatch (defined as core volume<50 ml, perfusion lesion volume>15 ml, mismatch ratio>1.8). Patients were grouped by onset to imaging time (<3, 3-4.5, 4.5-6 h). We explored correlates of penumbra proportion by multivariable linear regression. Results: Analysis included 144 subjects. Across time epochs, neither proportions of penumbra (59%, 64%, 75% at <3, 3-4.5, >4. 5 h, respectively, p = 0.4) nor poor collaterals (15/56 (27%), 14/47 (30%), 4/15 (27%) at <3, 3-4.5, >4.5 h, p=0.9) differed significantly. Penumbra proportion was not clearly related to time to imaging (R2=0.003; p=0.5) but a trend for divergent effects by collateral status was seen (slight increase in penumbra over time with good collaterals versus reduced with poor, interaction=0.08). The proportion of patients with target mismatch did not vary by time (56%, 74%, and 67% at <3, 3-4.5, >4.5 h, p=0.09). Conclusions: In a cross-sectional sample imaged within 6 h, neither the proportions of penumbral tissue nor "target mismatch" varied by time from onset. A trend for reducing penumbra proportion only among those with poor collaterals may have pathophysiological and therapeutic importance. [ABSTRACT FROM AUTHOR]

ESCAPE is a prospective, multicenter, randomized clinical trial that will enroll subjects with the following main inclusion criteria: less than 12 h from symptom onset, age > 18, baseline NIHSS >5, ASPECTS score of >5 and CTA evidence of carotid T/ L or M1 segment MCA occlusion, and at least moderate collaterals by CTA. The trial will determine if endovascular treatment will result in higher rates of favorable outcome compared with standard medical therapy alone. Patient populations that are eligible include those receiving IV tPA, tPA ineligible and unwitnessed onset or wake up strokes with 12 h of last seen normal. The primary end-point, based on intention-to-treat criteria is the distribution of modified Rankin Scale scores at 90 days assessed using a proportional odds model. The projected maximum sample size is 500 subjects. Randomization is stratified under a minimization process using age, gender, baseline NIHSS, baseline ASPECTS (8-10 vs. 6-7), IV tPA treatment and occlusion location ( ICA vs. MCA) as covariates. The study will have one formal interim analysis after 300 subjects have been accrued. Secondary end-points at 90 days include the following: mRS 0-1; mRS 0-2; Barthel 95-100, EuroQOL and a cognitive battery. Safety outcomes are symptomatic ICH, major bleeding, contrast nephropathy, total radiation dose, malignant MCA infarction, hemicraniectomy and mortality at 90 days. [ABSTRACT FROM AUTHOR]

Thrombi, or clots, often occlude proximal segments of the cerebral arterial circulation in acute ischemic stroke. Thromboembolic occlusion or thrombi superimposed on atherosclerotic plaque are the principal focus of acute stroke therapies such as thrombolysis or thrombectomy. We review the imaging characteristics of thrombi on multimodal computed tomography and magnetic resonance imaging, angiography, and ultrasonography, summarizing recent studies that facilitate therapeutic decision-making from these noninvasive studies. Information about the location, size, and imaging characteristics can be ascertained using these techniques. Imaging findings in relation to occlusive thrombus have been correlated with clot pathology, response to therapeutic interventions, and clinical outcome. Diagnostic evaluation of occlusive thrombi on noninvasive studies now constitutes an integral component of acute stroke management. [ABSTRACT FROM AUTHOR]

Background In stroke patients, collateral flow can rapidly be assessed on computed tomography angiography (CTA). Aims In this study, the impact of baseline collaterals on early outcome and risk of symptomatic intracerebral hemorrhages after systemic thrombolysis in patients with proximal arterial occlusions within the anterior circulation were analyzed. Methods Collateralization scores were determined on the CT angiography source images (0 = absent; 1 ≤ 50%, 2 > 50% but <100%, and 3 = 100% collateral filling) of patients with distal intracranial carotid artery and/or M1 segment occlusions treated from 2008 to December 2011. A collateral score of 0 to 1 was designated as poor and 2 to 3 as good collateral vessel status. Outcome variables included in hospital mortality, favorable outcome at discharge (modified Rankin score ≤ 2), and rates of symptomatic intracerebral hemorrhage based on the European- Australasian Acute Stroke Study II definition. Results Among 246 subjects (mean age of 74 years; median National Institutes of Health Stroke Scale N at admission 14), 205 patients (83%) had good collaterals, whereas 41 patients (17%) had poor collaterals, respectively. Patients with poor collaterals had significantly higher rates of in-hospital mortality (41% vs. 12%, P < 0·001), of symptomatic intracerebral hemorrhage (15% vs. 4·9%, P < 0·05) and had significantly lower rates of favorable early clinical outcome (0% vs. 28%, P < 0·001) compared with those with good collaterals. The grade of collateralization was independently associated with in-hospital mortality ( P < 0·001), early clinical outcome ( P < 0·01), and rates of symptomatic intracerebral hemorrhage ( P < 0·01). Conclusion Patients with proximal arterial occlusions within the anterior circulation and poor baseline collaterals have a poor early functional outcome and high rates of symptomatic intracerebral hemorrhage after systemic thrombolysis. Since similar findings have also been reported after endovascular therapy, strategies to improve collateral blood flow should be assessed in this patient population. [ABSTRACT FROM AUTHOR]