Late Window Research Articles

Beyond conventional imaging: A systematic review and meta-analysis assessing the impact of computed tomography perfusion on ischemic stroke outcomes in the late window.

Non-contrast cranial computed tomography (NCCT) and CT angiogram (CTA) have become essential for endovascular treatment (EVT) in acute stroke. Patient selection may improve when CT perfusion (CTP) imaging is also added for patient selection. We aimed to analyze the effects of implementing CTP in acute ischemic stroke (AIS) patients' treatment to assess whether stroke outcomes differ in the late window. We searched the PubMed, Embase, and Web of Sciences databases to obtain articles related to CTA and CTP in EVT. Collected patient data were split into two groups: the CTP and control (NCCT + CTA) cohorts. Primary outcomes evaluated were modified Rankin Scale (mRS) scores, symptomatic intracranial hemorrhages (sICHs), mortality, and successful recanalization. There were 14 studies with 5809 total patients in the final analysis: 2602 received CTP and 3202 were in the control group. CTP/CTA patients showed significantly lower rates of 90-day stroke-related mortality (odds ratio (OR) = 0.72, 95% confidence interval (CI) = 0.60-0.87, p < 0.01) and significantly higher successful recanalization (OR = 1.42, 95% CI = 1.06-1.94, p < 0.01) compared with CTA-only patients. Analysis of other outcomes including functional independence (mRS = 0-2), critical times, and intracranial hemorrhages was non-significant (p > 0.05). The study highlights the usefulness of CTP-guided therapy as a supplementary tool in EVT selection in the late window. Although the addition of CTP resulted in lower mortality, the favorable outcomes did not improve. Further evidence is required to establish a clearer understanding of the potential advantages or limitations of incorporating CTP in stroke imaging.

Impact of time from symptom onset to puncture, and puncture to reperfusion, in endovascular therapy in the late time window (>6 hours).

Background- Increased times from symptom onset to puncture (TSOP) and from puncture to reperfusion (TPTR) are associated with worse outcome in ischemic stroke patients treated with endovascular therapy (EVT) in the early time window (<6 hours). However, these associations are less described in the late window (>6 hours), where patients may benefit from EVT because of a more favorable imaging profile (late window paradox). We sought to compare the effect of these timeframes between these two periods on efficacy and safety outcomes.Methods- The ETIS Registry (Endovascular Treatment in Ischemic Stroke) is an ongoing, prospective, observational study in 21 centers that perform EVT in France. We included adult patients with an anterior occlusion, successfully treated by EVT (mTICI 2b-3) between January 2015 and June 2023, with a known time of stroke onset. The cohort was divided into 2 groups according to the TSOP (≤6h vs >6h). Primary outcome was favorable outcome (modified Rankin Scale 0-2 at 90 days).Results- 7,516 patients were included, with 5,936 patients being treated ≤6h and 1,580 >6h. In the early window, TSOP and TPTR were associated with worse outcomes at 90 days (adjusted OR=0.68 per hour; 95%CI, 0.64-0.73; p<0.001 and aOR=0.92 per 10 minutes increment; 95%CI, 0.90-0.94, p<0.001, respectively). TSOP was not associated with worse outcomes at 90 days in the late window (p=0.955), but TPTR was associated with worse outcomes (aOR=0.91 per 10 minutes increment; 95%CI, 0.86-0.96, p=0.001), every 10 additional minutes in TPTR being associated with a 1.7% (95%CI, 0.6%-2.7%) decreased probability of favorable outcome.Conclusions- Only EVT procedural time is associated to unfavorable outcomes at 90 days in late window patients. These results highlight how the late window paradox may end at the start of EVT and underscore the need for timely management, particularly for the EVT, even for late window patients with a presumed more favorable imaging profile.

Outcomes of Mechanical Thrombectomy for Patients With Stroke Presenting With Low Alberta Stroke Program Early Computed Tomography Score in Early and Late Time Windows.

This study aimed to compare outcomes of low Alberta Stroke Program Early Computed Tomography Score (ASPECTS) patients with stroke who underwent mechanical thrombectomy (MT) within 6 hours or 6 to 24 hours after stroke onset. A retrospective cohort study was conducted using data from a large multicenter international registry from 2013 to 2023. Patients with low ASPECTS (2-5) who underwent MT for anterior circulation intracranial large vessel occlusion were included. A propensity matching analysis was conducted for patients presented in the early (<6 hours) vs late (6-24 hours) time window after symptom onset or last known normal. Among the 10 229 patients who underwent MT, 274 met the inclusion criteria. 122 (44.5%) patients were treated in the late window. Early window patients were older (median age, 74 years [IQR, 63-80] vs 66.5 years [IQR, 54-77]; P < .001), had lower proportion of female patients (40.1% vs 54.1%; P = .029), higher median admission National Institutes of Health Stroke Scale score (20 [IQR, 16-24] vs 19 [IQR, 14-22]; P = .004), and a higher prevalence of atrial fibrillation (46.1% vs 27.3; P = .002). Propensity matching yielded a well-matched cohort of 84 patients in each group. Comparing the matched cohorts showed there was no significant difference in acceptable outcomes at 90 days between the 2 groups (odds ratio = 0.90 [95% CI = 0.47-1.71]; P = .70). However, the rate of symptomatic ICH was significantly higher in the early window group compared with the late window group (odds ratio = 2.44 [95% CI = 1.06-6.02]; P = .04). Among patients with anterior circulation large vessel occlusion and low ASPECTS, MT seems to provide a similar benefit to functional outcome for patients presenting <6 hours or 6 to 24 hours after onset.

Acute exercise performed during the late consolidation phase improves memory persistence by hippocampal protein synthesis and catecholamine modulation

Memory persistence is a crucial aspect of long-term memory (LTM) and involves late consolidation processes that modulate memory stability over time. Acute physical exercise (PE) has emerged as a potential strategy to modulate memory consolidation and enhance memory persistence. While its effects have been extensively explored in the early consolidation phase, its impact on the late phase remains unexplored. In this study, we investigated the effects and mechanisms of an acute PE on the late consolidation window of novel object recognition (NOR) memory in rats. A 30-minute running session applied 11 h after NOR memory acquisition significantly increased memory persistence for at least 7 days. The inhibition of hippocampal protein synthesis immediately after acute PE using anisomycin (a ribosomal inhibitor) or rapamycin (an mTOR pathway inhibitor) impaired the effect of PE on memory persistence. Animals only presented memory 1 day after acquisition. The same effect was observed with the inhibition of beta-adrenergic receptors by timolol. Although there were no differences between the groups' comparison, blocking D1/D5 receptors after acute PE resulted in a lack of memory persistence in the dichotomous testing (remember/non-remember). Therefore, our exploration of the mechanisms underlying this enhancement revealed the involvement of protein synthesis and the requirement of beta-adrenergic and dopaminergic D1/D5 receptors in the dorsal hippocampus. These findings provide valuable insights into PE as a potential memory modulator, contributing to expanding our understanding of memory consolidation dynamics and acute PE effects.

Delayed door to puncture time during off-duty hours is associated with unfavorable outcomes after mechanical thrombectomy in the early window of acute ischemic stroke

BackgroundsThe impact of off-duty hours mechanical thrombectomy on outcomes remains a subject of controversy. The impacts of off-duty hours on procedures are influenced by various factors, but the most critical one is the time delay in initiating the procedure after the patient’s arrival at the emergency room. Recently, a report suggested that the impact of time delay on post-procedural outcomes is evident in patients who arrive at the emergency room within 6 h of symptom onset, referred to as the “early window.” We hypothesized that the impact of procedure delays on outcomes during off duty-hours would be most significant within this early window. This study aimed to investigate the impact of door-to-puncture time (DTPT) delays in patients who underwent mechanical thrombectomy for acute ischemic stroke (AIS) during off-duty hours in both the early and late time windows.MethodsWe investigated patients who presented to the emergency center between 2014 and 2022. Among a total of 6,496 AIS patients, we selected those who underwent mechanical thrombectomy within 24 h of the onset of acute anterior circulation occlusion. The eligible patients were divided into two groups: those who arrived within 6 h of symptom onset and received the procedure within 8 h (early window), and those who received the procedure between 8 h and 24 h after symptom onset (late window). The study assessed the association between the onset to puncture time in each group and poor outcomes, measured by the modified Rankin scores(mRs) at 90 days. Furthermore, the study analyzed the impact of receiving the procedure during off-hours in both the early and late windows on outcomes. Specifically, the analysis focused on the impact of delayed DTPT in patients during off-duty hours on outcomes measured by the 90-days mRS.ResultsAmong the eligible patients, a total of 501 AIS patients underwent mechanical thrombectomy for acute anterior circulation occlusion within 24 h. Of these, 395 patients (78.8%) fell into the early window category, and 320 patients (63.9%) underwent the procedure during off-duty hours. In the early window, for every 60-minute increase in OTPT, the probability of occurrence a poor outcome at 90 days significantly increased in the fully adjusted model (OR = 1.21; 95% CI, 1.02 to 1.43; p = 0.03). In the early window, delayed procedures during off-duty hours (exceeding 103 min of DTPT) were identified as an independent predictor of poor outcomes (OR = 1.85; 95% CI, 1.05 to 3.24; p = 0.03). However, in the late window, there was no association between DTPT and outcomes at 90 days, and the impact of DTPT delays during off-hours was not observed.ConclusionsThrough this study, it became evident that the impacts of off-duty hours in mechanical thrombectomy were most pronounced in the early window, where the impact of time delay was clear. Therefore, it is believed that improvements in the treatment system are necessary to address this issue.

Vertebrobasilar Artery Occlusion Treatment Outcomes Within 24 hours of Estimated Occlusion Time.

The aim of this study was to investigate the efficacy and safety of endovascular treatment (EVT) in patients with acute vertebrobasilar artery occlusion (VBAO) within 24 hours of estimated occlusion time (EOT) and to evaluate the effect of early and late time window in a cohort of patients with VBAO treated with EVT. Retrospective analysis was conducted on patients within 24 hours of the EOT in 65 stroke centers in China. Favorable outcome was defined as modified Rankin Scale ≤3 at 90 days. Patients were divided into the medical management (MM) group and the EVT group. Times were dichotomized into early (EOT ≤6 hours) and late (>6 hours) time windows. Multivariate logical regression models were used to evaluate the efficacy and safety of EVT and the effect of time windows on outcomes in EVT patients. Among 4124 patients, 2473 and 1651 patients were included in the early and late windows, respectively. 1702 patients received MM and 2422 were treated with EVT. EVT was associated with a higher rate of a favorable outcome at 90 days both in early (odds ratio [OR] 2.16, 95% CI 1.94-2.41) and late (OR 1.89, 95% CI 1.65-2.17) time windows. No differences were found regarding favorable outcome (OR 0.95, 95% CI 0.87-1.03) between VBAO patients treated with EVT within and beyond 6 hours. Patients with acute VBAO who received EVT within 24 hours were associated with improved favorable outcome compared with patients who received MM. EVT beyond 6 hours is feasible and safe with no increase in symptomatic intracranial hemorrhage.

Perfusion Imaging‐Based Triage for Acute Ischemic Stroke: Trends in Use and Impact on Clinical Outcomes

Background Perfusion imaging (PI) serves as a valuable tool for triaging patients with acute ischemic stroke for endovascular treatment (EVT). This study aims to investigate trends in PI use and its impacts on EVT rates and clinical outcomes, particularly focusing on variations across different time windows. Methods Data from a prospective, nationwide, acute stroke registry in South Korea were analyzed retrospectively. PI was regarded as treatment‐decision imaging when conducted either (1) prior to EVT, or (2) within 3 hours from hospital arrival in patients not receiving EVT. The study spanned 3 epochs: 2011–2014, 2015–2017, and 2018–2021. Based on the time from onset to arrival, patients were categorized into 2 time windows: early (0–6 hours) and late (6–24 hours). We evaluated EVT rates and clinical outcomes in patients with anterior large vessel occlusion. Results From 2011 to 2021 among 49 449 patients with acute ischemic stroke presenting within 24 hours of onset, PI use rates declined from 36.9% to 30.1%. In the early window, rates dropped from 48.4% to 32.4%, whereas in the late window, they increased from 23.5% to 27.8%. Factors such as older age, atrial fibrillation, anterior large vessel occlusion, and severe stroke were associated with higher rates in the late window. Conversely, younger age and male sex were associated with higher rates in the early window. For patients with anterior large vessel occlusion, PI use increased the likelihood of receiving EVT in the late window and minimized the risk of symptomatic intracranial hemorrhage in the early window. However, 3‐month functional outcomes and mortality were. unaffected. Conclusion The study revealed distinct trends in PI use across early and late time windows, indicating varying roles of PI in these time frames. However, the definitive value and necessity of PI in guiding EVT decision‐making remain unclear, underscoring the need for further research

Validation of a model for outcome prediction after endovascular treatment for ischemic stroke.

The recently developed MR-PREDICTS@24 h model showed excellent performance in the MR-CLEAN Registry cohort in patients presenting within 12 h from onset. However, its applicability to an U.S. population and to patients presenting beyond 12 h from last known normal are still undetermined. We aim to externally validate the MR-PREDICTS@24 h model in a new geographic setting and in the late window. In this retrospective analysis of a prospectively collected database from a comprehensive stroke center in the United States, we included patients with intracranial carotid artery or middle cerebral artery M1 or M2 segment occlusions who underwent endovascular therapy and applied the MR-PREDICTS@24 h formula to estimate the probabilities of functional outcome at day 90. The primary endpoint was the modified Rankin Scale (mRS) at 90 days. We included 1246 patients, 879 in the early (<12 h) and 367 in the late (≥12 h) cohort. For both cohorts, calibration and discrimination of the model were accurate throughout mRS levels, with absolute differences between estimated and predicted proportions ranging from 1% to 5%. Calibration metrics and curve inspections showed good performance for estimating the probabilities of mRS ≤ 1 to mRS ≤ 5 for the early cohort. For the late cohort, predictions were reliable for the probabilities of mRS ≤ 1 to mRS ≤ 4. The MR-PREDICTS@24 h was transferrable to a real-world U.S.-based cohort in the early window and showed consistently accurate predictions for patients presenting in the late window without need for updating.

Experimental investigation of hydrocarbon generation, retention, and expulsion of saline lacustrine shale: Insights from improved semi-open pyrolysis experiments of Lucaogou Shale, eastern Junggar Basin, China

The organic-rich shale deposited in a saline lacustrine setting contributes massive conventional and unconventional petroleum reserves. However, the hydrocarbon generation, retention, and expulsion of saline lacustrine shale with increasing thermal maturity were rarely reported. Predicting the quality and quantity of generated, retained, and expelled hydrocarbons under various maturity stages for a given shale before drilling persists as a vital issue in exploration. Here, this study conducted two improved semi-open pyrolysis experiments to investigate the characteristics of the hydrocarbon generation, retention, and expulsion of Lucaogou Shale. Solid residues, adsorbed oil, free oil, expelled oil, and hydrocarbon gases were carefully quantified during the pyrolysis experiments. The results reveal that the composition and quantity of generated hydrocarbons are determined by the maturity and degree of openness of the shale system. The Tasmanites of Lucaogou Shale rapidly were converted to abundant oil in the main oil stage, promoting oil retention and expulsion. Meanwhile, the yield of adsorbed and free oil reached its peak at the VRo of 1.01 %. In the late oil window, the previously retained oil was further expelled from the shale as thermal stress increased. High oil retention significantly promoted the generation of extensive wet gas due to secondary cracking within the gas window. However, in a more open system, most of the generated oil was expelled within the oil window. The Lucaogou Shale generates relatively small amounts of hydrocarbon gas through kerogen cracking within the gas window. Hence, the extent of oil transformation into gas is controlled by the residence time and quantity of retained oil in shale. In addition, the maturity range of the oil saturation index greater than 100 mg oil/g TOC in Lucaogou Shale is relatively wide (VRo of 0.9 %-1.5 %), consistent with the renowned Woodford Shale. Expanded geochemical data of natural shale and artificial maturation experiments indicate the distribution of potential hydrocarbon resources. These valuable insights enhance the possibility of searching for commercial shale oil and conventional hydrocarbon resources. Collectively, these findings provide critical new insights into the hydrocarbon generation, retention, and expulsion of saline lacustrine shale, and the results could be a valuable analog for other saline lacustrine petroleum systems worldwide.

CLEAR Thrombectomy Score: An Index to Estimate the Probability of Good Functional Outcome With or Without Endovascular Treatment in the Late Window for Anterior Circulation Occlusion.

With the expanding eligibility for endovascular therapy (EVT) of patients presenting in the late window (6-24 hours after last known well), we aimed to derive a score to predict favorable outcomes associated with EVT versus best medical management. A multinational observational cohort of patients from the CLEAR (Computed Tomography for Late Endovascular Reperfusion) study with proximal intracranial occlusion (2014-2022) was queried (n=58 sites). Logistic regression analyses were used to derive a 9-point score for predicting good functional outcome (modified Rankin Scale score 0-2 or return to premorbid modified Rankin Scale score) at 90 days, with sensitivity analyses for prespecified subgroups conducted using bootstrapped random forest regressions. Secondary outcomes included 90-day functional independence (modified Rankin Scale score 0-2), poor outcome (modified Rankin Scale score 5-6), and 90-day survival. The score was externally validated with a single-center cohort (2014-2023). Of the 3231 included patients (n=2499 EVT), a 9-point score included age, early computed tomography ischemic changes, and stroke severity, with higher points indicating a higher probability of a good functional outcome. The areas under the curve for the primary outcome among EVT and best medical management subgroups were 0.72 (95% CI, 0.70-0.74) and 0.87 (95% CI, 0.84-0.90), respectively, with similar performance in the external validation cohort (area under the curve, 0.71 [95% CI, 0.66-0.76]). There was a significant interaction between the score and EVT for good functional outcome, functional independence, and poor outcome (all Pinteraction<0.001), with greater benefit favoring patients with lower and midrange scores. This score is a pragmatic tool that can estimate the probability of a good outcome with EVT in the late window. URL: https://www.Clinicaltrials.gov; Unique identifier: NCT04096248.

Shared neural codes of recognition memory

Recognition memory research has identified several electrophysiological indicators of successful memory retrieval, known as old-new effects. These effects have been observed in different sensory domains using various stimulus types, but little attention has been given to their similarity or distinctiveness and the underlying processes they may share. Here, a data-driven approach was taken to investigate the temporal evolution of shared information content between different memory conditions using openly available EEG data from healthy human participants of both sexes, taken from six experiments. A test dataset involving personally highly familiar and unfamiliar faces was used. The results show that neural signals of recognition memory for face stimuli were highly generalized starting from around 200 ms following stimulus onset. When training was performed on non-face datasets, an early (around 200–300 ms) to late (post-400 ms) differentiation was observed over most regions of interest. Successful cross-classification for non-face stimuli (music and object/scene associations) was most pronounced in late period. Additionally, a striking dissociation was observed between familiar and remembered objects, with shared signals present only in the late window for correctly remembered objects, while cross-classification for familiar objects was successful in the early period as well. These findings suggest that late neural signals of memory retrieval generalize across sensory modalities and stimulus types, and the dissociation between familiar and remembered objects may provide insight into the underlying processes.

Collateral-based selection for endovascular treatment of acute ischaemic stroke in the late window (MR CLEAN-LATE): 2-year follow-up of a phase 3, multicentre, open-label, randomised controlled trial in the Netherlands

The MR CLEAN-LATE trial provided evidence for the safety and efficacy of endovascular treatment for acute ischaemic stroke within the late window (after 6-24 h) in patients who were preselected based on the presence of collateral flow on CT angiography. We aimed to evaluate clinical outcomes 2 years after randomisation. MR CLEAN-LATE was a phase 3, multicentre, open-label, blinded-endpoint, randomised controlled trial conducted at 18 stroke intervention centres in the Netherlands. If endovascular treatment could be initiated within 6-24 h of symptom onset or last seen well, patients (aged 18 years or older) with an acute ischaemic stroke due to a large vessel occlusion in the anterior circulation and at least some collateral flow in the affected middle cerebral artery territory on CT angiography were randomly assigned (1:1) to either endovascular treatment with best medical treatment (endovascular treatment group) or best medical treatment alone (control group). Web-based randomisation, stratified by centre, was performed with the use of permuted blocks (block size eight to 20). The researchers who collected clinical outcomes and analysed the results were masked to treatment allocation; treating physicians, local investigators, and patients were aware of the received treatment. The primary outcome of MR CLEAN-LATE was the modified Rankin Scale (mRS) score at 90 days after randomisation. For this 2-year prespecified analysis, the primary outcome was mRS score at 2 years (minus 3 months to plus 6 months). Primary and safety analyses were performed based on the modified intention-to-treat principle, and included patients who provided (deferred) consent or died before consent could be obtained. Missing data were handled with multiple imputation by chained equations. The trial is completed and is registered at ISRCTN, ISRCTN19922220. Between Feb 2, 2018, and Jan 27, 2022, 535 patients were randomly assigned in the MR CLEAN-LATE trial, of whom 502 (94%) gave deferred consent and comprised the modified intention-to-treat population (255 in the endovascular treatment group and 247 in the control group). 261 (52%) patients were female and 241 (48%) were male. Data for mRS score at 2 years were available for 226 (89%) patients in the endovascular treatment group and for 202 (82%) patients in the control group. The median mRS score at 2 years was 4 (IQR 2-6) in the endovascular treatment group and 6 (2-6) in the control group. The endovascular treatment group demonstrated a shift towards better functional outcomes on the mRS (adjusted common odds ratio 1·41 [95% CI 1·00-1·99]; p=0·049). All-cause mortality at 2 years was 34% (87 of 255) in the endovascular treatment group and 41% (101 of 247) in the control group (adjusted hazard ratio 0·81 [95% CI 0·60-1·08]; p=0·15). Major vascular events (ie, transient ischaemic attack, ischaemic stroke, haemorrhagic stroke, and cardiac events) were reported between 90 days and 2 years in 23 patients in the endovascular treatment group and 13 patients in the control group. Our results show that the effectiveness of late-window (after 6-24 h) endovascular treatment in improving clinical outcomes is sustained for up to 2 years in a population preselected based on the presence of collateral flow on CT angiography. This finding might be important for prompting further evaluations of cost-effectiveness, health-care policy development, and clinical decision making. The Dutch Organization for Health Research and Health Innovation (ZonMW), Collaboration for New Treatments of Acute Stroke Consortium, Dutch Heart Foundation, Stryker, Medtronic, Cerenovus, Health Holland Top Sector Life Sciences & Health, and the Netherlands Brain Foundation.

The impacts of venous outflow profiles on outcomes among large vessel occlusion patients receiving endovascular treatment in the late window.

To investigate the association between venous outflow (VO) profiles and outcomes among acute ischemic stroke caused by anterior circulation large vessel occlusion (AIS-LVO) patients who had undergone endovascular treatment (EVT) in the late window of 6-24 h from stroke onset. This was a post-hoc analysis of our preceding RESCUE-BT trial, with findings validated in an external cohort. Baseline computed tomographic angiography (CTA) was performed to assess VO using the Cortical Vein Opacification Score (COVES). The primary clinical outcome was functional independence at 90 days (modified Rankin Scale score of 0-2). The adjusted odd ratio (aOR) and confidence interval (CI) were obtained from multivariable logistic regressions. A total of 440 patients were included in the present study. After identifying the cutoff of COVES by marginal effects approach, enrolled patients were divided into the favorable VO group (COVES 4-6) and the poor VO (COVES 0-3) group. Multivariable logistic regression analysis showed that favorable VO (aOR 2.25; 95% CI 1.31-3.86; p = 0.003) was associated with functional independence. Similar results were detected in the external validation cohort. Among those with poor arterial collateralization, favorable VO was still an independent predictor of functional independence (aOR 2.09; 95% CI 1.06-4.10; p = 0.032). The robust VO profile indicated by COVES 4-6 could promote the frequency of functional independence among AIS-LVO patients receiving EVT in the late window, and the prognostic value of VO was independent of the arterial collateral status. The robust venous outflow profile was a valid predictor for functional independence among AIS-LVO patients receiving EVT in the late window (6-24 h) and the predictive role of venous outflow did not rely on the status of arterial collateral circulation.

Tracing Oils and Gas Accumulation in Complex Petroleum Systems Based on Biomarkers, Light Hydrocarbons, and Diamondoids from Concomitant Crude Oils: A Case Study in the Shawan Sag of the Junggar Basin, NW China.

The Shawan Sag is one of the most promising blocks in the western Junggar Basin for natural gas and oil exploration. To date, the research and exploration degree here is still low, and there is limited understanding of the origin and migration of natural gas and oils, which seriously restricts future exploration and development. At least three oil charging episodes and one gas charging episode could be confirmed in the reservoirs on the western slope of the Shawan Sag based on the analysis of concentrations and ratios of hopanes and steranes, diamondoids, and light hydrocarbons. The first and second charging oils originated from the peak and late oil generation window stages of Lower Permian Fengcheng Formation (P1f) source rocks, respectively. The third charging oil originated from the late oil generation window stage of source rocks of the Middle Permian lower Wuerhe Formation (P2w). Combining the carbon isotopic compositions and the gas composition, the fourth charging gas was derived from the postmature source rocks of Carboniferous(C) and Lower Permian Jiamuhe Formation (P1j) and the high-postmature source rock of Lower Permian Fengcheng Formation (P1f). The preservation conditions of nature gas in the Mesozoic (T-K) cap rocks in the Shawan Sag, as indicated by methyladamantanes (MAs)/methyldiamantanes (MDs) ratio, are better than those in the Mahu Sag. In this study, the methyladamantane maturity parameters of oils in the reservoirs were proposed to evaluate the maturity and further determine the migration direction of late-charging natural gas. The results suggest that late postmatured natural gases were charged from the southern part to the northwest of the Shawan Sag. Therefore, the southeastern direction of Well SP1 is a favorable area for natural gas exploration in the Shawan Sag. Meanwhile the northern part of the sag is favorable for the exploration of high-mature oil generated from source rocks within the Middle Permian Lower Wuerhe Formation.

Workflow and Outcome of Thrombectomy in Late Time Window: A Pooled Multicenter Analysis.

We investigated the impact of workflow times on the outcomes of patients treated with endovascular thrombectomy (EVT) in the late time window. Individual patients' data who underwent EVT in the late time window (onset to imaging >6 hours) were pooled from seven registries and randomized clinical trials. Multiple time intervals were analyzed. Mixed-effects logistic regression was used to estimate the likelihood of functional independence at 90 days (modified Rankin Scale 0-2). Mixed-effects negative binomial regression was used to evaluate the relationship between patient characteristics and workflow time intervals. 608 patients were included. The median age was 70 years (IQR: 58-71), 307 (50.5%) were female, and 310 (53.2%) had wake-up strokes. Successful reperfusion was achieved in 493 (81.2%) patients, and 262 (44.9%) achieved 90-day mRS 0-2. The estimated odds of functional independence decreased by 13% for every 30 minute delay from emergency department (ED) arrival to imaging time and by 7% from ED arrival to the end of EVT in the entire cohort. Also, the estimated odds of functional independence decreased by 33% for every 30 minute delay in the interval from arterial puncture to end of EVT, 16% in the interval from arrival in ED to end of EVT and 6% in the interval from stroke onset to end of EVT among patients who had a wake-up stroke. Faster workflow from ED arrival to end of EVT is associated with improved functional independence among stroke patients treated in the late window.

Brain imaging prior to thrombectomy in the late window of large vessel occlusion ischemic stroke: a systematic review and meta-analysis.

Optimal imaging modalities to select patients for endovascular thrombectomy (EVT) in the late window of acute ischemic stroke due to large vessel occlusions (AIS-LVO) are not known. We conducted a systematic review comparing outcomes of patients selected by non-contrast computed tomography (NCCT)/CT angiography (CTA) vs. those selected by CT perfusion (CTP) or magnetic resonance imaging (MRI) for EVT in these patients. We searched PUBMED, EMBASE, and the Cochrane Library from January 1, 2000, to July 15, 2023, to identify studies comparing outcomes of patients selected for EVT by NCCT/CTA vs. CTP or MRI in the late time window for AIS-LVO. Primary outcome was independence (mRS 0-2) at 90days or discharge. Secondary outcomes were symptomatic intracranial hemorrhage (sICH) and mortality. We pooled data across studies based on an inverse variance method. Six cohort studies with 4208 patients were included. Pooled results showed no significant difference in the rate of independence at 90days or discharge (RR 0.96, 95% CI 0.88-1.03) and sICH (RR 1.26, 0.85-1.86) between patients selected by NCCT/CTA vs. CTP or MRI for EVT in the late window of AIS-LVO. However, patients selected by NCCT/CTA vs. CTP or MRI for EVT were associated with a higher risk of mortality (RR 1.21, 1.06-1.39). For AIS-LVO in the late window, patients selected by NCCT/CTA compared with those selected by CTP or MRI for EVT might have a comparable rate of functional independence and sICH. Baseline NCCT/CTA may triage AIS-LVO in the late window.

Depositional environments and source rock potential of some Upper Palaeozoic (Devonian) coals on Bjørnøya, Western Barents shelf

Upper Palaeozoic strata are potential sources for hydrocarbon plays on the Norwegian Barents Shelf. The island of Bjørnøya (Bear Island) is located on the western margin of the Barents Shelf and represents an exposed part of the Stappen High, which makes it an excellent location to investigate the source rock potential of this succession. Here, we investigate the organic geochemical composition and source rock potential of coals and organic-rich mudstones of Late Devonian to middle Permian ages. The thermal maturity of the analysed samples ranges from mature to overmature with some samples being in the late oil generation window, and thus exhibiting higher maturities than age and facies equivalent strata in central Spitsbergen in the NW corner of the Barents Shelf and on the Finnmark Platform to the south. The high maturities and thermal cracking may thus have negatively affected the applied isoprenoid and biomarker-based source facies parameters, which potentially inhibit correct source facies interpretation. However, our results and comparisons with previous studies indicate that the vitrinite- and inertinite-dominated humic coals occurring in the lower part of the succession formed by the accumulation of peat in fluvially-influenced, humid wetlands at paleo-equatorial latitudes during a pronounced episode of rifting in the Late Devonian (Famennian) to earliest Carboniferous (Mississippian). Our source rock evaluation indicates a good potential for liquid hydrocarbon generation for the coals of the Upper Devonian Røedvika Formation prior to maturation. The oil-prone organic matter of these coals is primarily considered as terrestrial and non-aqueous. Because of renewed rifting in the middle Carboniferous combined with a shift to arid climatic conditions, as well as an environmental change from dominantly terrestrial and marginal marine clastic to marine carbonate platform environments, the accumulation of wetland peats effectively came to an end. Thus, the overlying Carboniferous and Permian strata generally seems to yield poor to no hydrocarbon generation potential.

Abstract WMP62: Infarct Core Volume Estimation on Non-Contrast Computed Tomography in Late Window Patients Using a Machine Learning Algorithm Software

Introduction: A simplified patient selection paradigm can reduce time to reperfusion and widen the eligibility of large vessel occlusions (LVO) for endovascular therapy (EVT). We developed and externally validated a machine learning (ML) algorithm to estimate infarct core volume (ICV) on non-contrast computed tomography (NCCT) in anterior circulation LVOs presenting in the late window (≥ 6-24 hours). Methods: LVOs from prospective databases in US and Spain were included. For development, 2858 stroke activations with NCCT/CT angiography[s1] were included. For validation, consecutive LVOs with admission NCCT/CT perfusion (CTP), post-EVT diffusion-weighted imaging (DWI) within 24 hours, and mTICI ≥2b were included. Neuroimaging experts adjudicated ASPECTS on NCCT and final infarct volume (FIV) on DWI (ground truth). ML algorithm was trained using UNet architecture with ResNet 34 encoder to identify ICV on NCCT. Estimated ICVs (algorithm, CTP [&lt;30% cerebral blood flow], and ASPECTS) were compared to ground truth using correlations (intraclass correlation coefficient [ICC] and Spearman’s [r s ]) and Bland Altman plots. Superiority tests between correlations (to compare modalities) and subgroup analyses were performed. Results: 98 patients (median age, 70 years; IQR:59-80; 51% females) were included for validation. Median time to first imaging was 11.4 hours (IQR:9.0-14.7). Correlations (Table) were moderate with the ML algorithm (ICC:0.59) and poor with ASPECTS (r s :-0.31) and CTP ICV (ICC:0.42;). Bland Altman plots showed that ML algorithm had a mean difference closest to zero (-34.2 mL) while the CTP ICV had a larger mean difference (-45.8 mL). Superiority tests (Table), [s2] ML algorithm correlation showed superiority to both the CTP ( p sup =.018) and ASPECTS ( p sup =.003) correlations. Conclusion: On late window patients, estimation of ICV on NCCT with the ML algorithm seems to be superior to CTP and ASPECTS. Further prospective studies are needed.

Abstract TMP96: Clear Thrombectomy Score: An Index to Estimate Probability of Good Functional Outcome Following Endovascular Treatment in the Late Window for Anterior Circulation Occlusion

Background: Endovascular thrombectomy (EVT) has established efficacy across a wide range of patient age, radiological findings, and clinical features. However, EVT may be less effective in extreme scenarios (e.g., large established infarction in later treatment windows), where there are currently limited data. Methods: A heterogeneous, multinational observational cohort (CLEAR registry) of consecutive adult patients ≥18 years old who underwent EVT for acute occlusion (2014-2022) of the internal carotid or proximal middle cerebral (M1 or M2) arteries was queried (n=64 sites). A high-fidelity model for predicting good functional outcome at 90 days (return to pre-stroke modified Rankin Scale [mRS] or mRS 0-2 after EVT) was developed using a binary, multivariable logit model with adaptive double lasso adjustment, which was validated using 5-fold cross validation and 1000 bootstrap sampling for confidence intervals. Results: At the time of the analysis, we evaluated 2953 patients from the registry treated with EVT, of which 1855 (63%) had complete covariate data for inclusion. The median National Institutes of Health Stroke Scale (NIHSS) score was 15 (IQR 9-20), with 14.0% having a pre-stroke mRS &gt;2, 8.3% having a NIHSS &lt;6, and 17.8% having an Alberta Stroke Program Early Computed Tomography Scale (ASPECTS) score ≤6. A good functional outcome occurred in 813 (43.8%) patients. Independent predictors of the primary outcome, with points allocated toward the final score, included younger age, higher ASPECTS, lower NIHSS, and time from last known well to arterial puncture. The areas under the curve for derivation and validation cohorts were 0.72 (95% CI 0.70-0.75) and 0.74 (95% CI 0.71-0.80), respectively. Discussion: The CLEAR thrombectomy score provides a simple, validated means of predicting good functional outcome following late-window, anterior circulation thrombectomy using routinely acquired clinical and imaging data. External validation is warranted.

Clinical Uncertainty in Large Vessel Occlusion ischemic stroke (CULVO): Does automated perfusion scanning make a difference? Protocol of an intrarater and interrater agreement study.

Guidelines recommend the use of perfusion computed tomography (CT) to identify emergent large vessel ischemic stroke (ELVIS) patients who are likely to benefit from endovascular thrombectomy (EVT) if they present within 6-24 hour (late window) of stroke onset. We aim to determine if the interrater and intrarater reliability among physicians when recommending EVT is significantly different when perfusion CT or non-perfusion CT is reviewed. A total of 30 non-consecutive patients will be selected from our institutional database comprising 3144 cranial CT scans performed for acute stroke symptoms January 2018 to August 2022. The clinical and radiologic data of the 30 patients will be presented in random order to a group of 29 physicians in two separate sessions at least three weeks apart. In each session, the physicians will evaluate each patient once with automated perfusion images and once without. We will use non-overlapping 95% confidence intervals and difference in agreement classification as criteria to suggest a difference between the Gwet AC1 statistics (κG). The results obtained from this study, combined with the clinical outcomes data of patients categorized through the two imaging techniques and a cost-effectiveness analysis, will offer a comprehensive evaluation of the clinical utility of perfusion CT neuroimaging. Should there be no significant disparity in the reliability of decisions made by clinicians using the two neuroimaging protocols, it may be necessary to revise existing recommendations regarding neuroimaging in the later time window to align with these findings.