Hypoperfusion Volume Research Articles

Association of critical hypoperfusion biomarkers on CT with futile recanalization and poor outcome after mechanical thrombectomy in acute ischemic stroke

Background and purposeWe aimed to investigate the association between critical perfusion delay and poor outcome among recanalized stroke patients with anterior large-vessel occlusion, and to use pretreatment hypoperfusion biomarkers on CT to predict futile recanalization even after successful thrombectomy.MethodsAn ischemic region with time-to-maximum (Tmax) > 12s–10s was defined as critical hypoperfusion, Tmax > 8s as moderate hypoperfusion, and hypoperfusion intensity ratio (HIR, volumetric ratio of Tmax > 10s / Tmax > 6s) represented for severity of critical hypoperfusion and rCBF < 30% for ischemic core. The associations between these CT perfusion characteristics and favorable or unfavorable outcome (mRS 0–2 versus 3–6) were analyzed in univariable regression, and a multivariable model was then used to predict futile recanalization.ResultsSeventy-nine stroke patients were included and had good grades of instant recanalization. Forty-two patients (53%) had poor outcomes, and they had a significantly larger volume of critical hypoperfusion as seen with Tmax > 10s and > 12s (P = 0.032 and 0.008, respectively), a larger volume of ischemic core (P = 0.011) and a higher HIR (P = 0.002) than those patients achieving good outcomes. In the univariable analysis, a lower HIR (OR, 0.008; 95%CI, 0.001–0.254, P = 0.006) was associated with favorable outcome. The volume size of Tmax > 12s was significantly and positively correlated with the size of ischemic core. A HIR value higher than 0.491 might predict a futile recanalization and poor outcome (AUC = 0.701).ConclusionsThe critical hypoperfusion biomarkers on CTP could be useful in triaging endovascular treatment and identifying stroke patients at risk of futile recanalization.

Insights into multilevel tissue-level collateral status using ColorViz maps from dual data sources in acute ischemic cerebrovascular diseases: A STARD-compliant retrospective study.

This study aims to explore the utility of ColorViz mapping from dual data sources for assessing arterial collateral circulation and predicting cerebral tissue-level collateral (TLC) in patients with acute ischemic cerebrovascular diseases. A retrospective study was conducted at a single center on a cohort of 79 patients diagnosed with acute ischemic cerebrovascular diseases between November 2021 and April 2022, who had undergone both multi-phase CT angiography (mCTA) and computed tomography perfusion (CTP). The quality of images and arterial collateral status depicted on ColorViz maps from dual data-sets (mCTA and CTP) were assessed using a "5-point scale" and a "10-point scale," respectively. The status of TLC was evaluated by analyzing multilevel hypoperfusion volume and the hypoperfusion intensity ratio (HIR). The Spearman correlation coefficient was employed to examine the association between arterial collateral status derived from dual data sources and TLC. Receiver operating characteristic curve analysis was used to determine the diagnostic efficacy in detecting large vessel occlusive acute ischemic stroke (LVO-AIS). The ColorViz maps derived from dual data sources facilitated comparable image quality, with over 95% of cases meeting diagnostic criteria, for the evaluation of arterial level collateral circulation. Patients with robust arterial collateral circulation, as determined by dual data sources, were more likely to exhibit favorable TLC status, as evidenced by reductions in hypoperfusion volume (Tmax > 4 seconds, Tmax > 6 seconds, Tmax > 8 seconds, and Tmax > 10 seconds, P < .05) and HIR (Tmax > 6 seconds/4 seconds, Tmax > 8 seconds/4 seconds, Tmax > 10 seconds/4 seconds, and Tmax > 8 seconds/6 seconds, P < .05). The sensitivity and specificity in detecting LVO-AIS was 60.00% and 97.73% for mCTA source maps, while 74.29% and 72.73% for CTP source maps (P > .05 based on De-Long test). In conclusion, this study indicates that ColorViz maps derived from both data sources are equally important in evaluating arterial collateral circulation and enhancing diagnostic efficiency in patients with LVO-AIS, as well as offering insights into the TLC status based on hypoperfusion volume and HIR.

Hypoperfusion index ratio and pretreatment with intravenous thrombolysis are independent predictors of good functional outcome in acute ischemic stroke patients with large vessel occlusion treated with acute reperfusion therapies.

We aimed to investigate the performance of several neuroimaging markers provided by perfusion imaging of Acute Ischemic Stroke (AIS) patients with large vessel occlusion (LVO) in order to predict clinical outcomes following reperfusion treatments. We prospectively evaluated consecutive AIS patients with LVO who were treated with reperfusion therapies, during a six-year period. In order to compare patients with good (mRS scores 0-2) and poor (mRS scores 3-6) functional outcomes, data regarding clinical characteristics, the Alberta Stroke Programme Early Computed Tomography Score (ASPECTS) based on unenhanced computed tomography (CT), CT angiography collateral status and perfusion parameters including ischemic core, hypoperfusion volume, mismatch volume between core and penumbra, Tmax > 10s volume, CBV index and the Hypoperfusion Index Ratio (HIR) were assessed. A total of 84 acute stroke patients with LVO who met all the inclusion criteria were enrolled. In multivariable logistic regression models increasing age (odds ratio [OR]: 0.93; 95%CI: 0.88-0.96, p = 0.001), lower admission National Institute of Health Stroke Scale (NIHSS)-score (OR: 0.88; 95%CI: 0.80-0.95, p = 0.004), pretreatment with intravenous thrombolysis (OR: 3.83; 95%CI: 1.29-12.49, p = 0.019) and HIR (OR:0.36; 95%CI: 0.10-0.95, p = 0.042) were independent predictors of good functional outcome at 3months. The initial univariable associations between HIR and higher likelihood for symptomatic intracranial hemorrhage (sICH) and parenchymal hematoma type 2 (PH2) were attenuated in multivariable analyses failing to reach statistical significance. Our pilot observational study of unselected AIS patients with LVO treated with reperfusion therapies demonstrated that pre-treatment low HIR in perfusion imaging and IVT were associated with better functional outcomes.

Assessment of Perfusion Volumes by a New Automated Software for Computed Tomography Perfusion

IntroductionTo compare the perfusion volumes assessed by a new automated CT perfusion (CTP) software iStroke with the circular singular value decomposition software RAPID and determine its predictive value for functional...

Abstract TP133: Clot Burden Score Correlates Best With Hypoperfusion Volume and Predicts Final Infarct ASPECTS&lt;=3 in Anterior Circulation Ischemic Strokes

Purpose: Clot Burden Score (CBS) is a semiquantitative measure of thrombus extent on CTA for proximal anterior circulation strokes whose relationship with perfusion metrics has not been fully explored. CBS has potential added value during stroke triage if perfusion imaging is not available or suboptimal. We aimed to investigate if CBS is (1) correlated to perfusion estimates of infarct core volume, hypoperfusion volume, or collateral status, and (2) a predictor of final infarct extent without reperfusion therapy. Methods: Retrospective analysis included consecutive patients (1) arriving &lt;24 hours from onset, (2) with occlusion in the intracranial ICA, M1, M2, or A1 or combination, (3) with concurrent CTP, and (4) had followup CT or DWI during hospitalization. CBS is a 10-point negative ordinal scale: 2-points subtracted for occlusion of supraclinoid ICA, proximal M1, or distal M1, and 1-point subtracted for occlusion of infraclinoid ICA, A1, or M2. Correlation of CBS with perfusion metrics was evaluated using Spearman's rank test. Final infarct ASPECTS were scored for those without thrombolysis or thrombectomy. Multivariate logistic regression was used to identify predictors of final ASPECTS&lt;=3 (approximating &gt;=100mL). ROC analysis was evaluated to assess performance and optimal thresholds. Results: 222 patients included with median (IQR) age of 75 (65-84) and NIHSS of 18 (11-24). Median CBS was 7 (6-9) and best correlated to Tmax&gt;6s r=-0.579 (hypoperfusion volume), followed by HIR r=-0.401 (collateral status) and rCBF&lt;30% r=-0.306 (core volume), all p&lt;0.001. 71 (32.0%) untreated patients also had median CBS of 7 (6-9). CBS and Tmax&gt;6s had the strongest correlation to final ASPECTS in this subgroup, r=0.637 and r=-0.686 (both p&lt;0.001). 22 of these (30.1%) had final ASPECTS&lt;=3. Multivariate logistic regression including CBS, Tmax&gt;6s, HIR, baseline ASPECTS, and NIHSS showed only CBS as independent predictor of final ASPECTS&lt;=3 (p&lt;0.001). ROC AUC for CBS was 0.902 [95% CI: 0.819-0.985] with optimal threshold of &lt;=6 for sensitivity 86.4% and specificity 81.6%. Conclusion: CBS as a measure of thrombus extent correlates best with baseline hypoperfusion volume on CTP and independently predicts very large final infarcts (ASPECTS&lt;=3) without treatment.

Abstract TP137: Quantitative Assessment of No-Reflow Zones Predicts Infarct Growth and Functional Outcome

Background: Technically successful but futile angiographic reperfusion (AR) has been reported in 20-50% of acute ischemic stroke patients undergoing endovascular treatment. Persistent occlusions at distal arteries and ischemic capillary bed (i.e. no-reflow phenomenon) have been shown as one of the culprits resulting in infarct growth and poor functional outcome despite thrombectomy. We aimed to quantify the residual no-reflow perfusion in patients who underwent successful AR and assess its effect on infarct growth and functional outcome. Methods: In this retrospective single institution study, patients with anterior circulation LVO, successful AR (TICI ≥ 2b), and pre and posttreatment MR perfusion (MRP) were included. Hypoperfusion volume along the affected territory was calculated on Tmax maps using thresholds &gt;2, 4, and 6 sec on both pre and posttreatment MRP scans. Infarct growth was calculated by subtracting baseline ischemic core from the final infarct volume. A total of 12 variables including demographic, clinical, and Tmax thresholds were evaluated to predict infarct growth and functional outcome (90day mRS). Results: A total of 50 patients met inclusion criteria, of whom 19 had infarct growth ≥ 10 mL while 31 had &lt; 10 mL infarct growth. Functional outcome was poor in 27 patients (90day mRS&gt;2). Univariate analysis showed no statistical significance (p&gt;0.05) for either of the baseline Tmax volumes in prediction of infarct growth or functional outcome. Posttreatment hypoperfusion (no-reflow volumes) was significant for prediction of infarct growth at all Tmax volumes (p=0.048, 0.023, 0.021 for Tmax &gt; 2, 4, and 6 sec respectively). Volume of Tmax &gt;6sec was significant (p=0.044) for prediction of poor functional outcome. Multivariate logistic regression analysis revealed Tmax &gt;6 sec residual hypoperfusion volume as an independent variable for prediction of infarct growth ≥ 10 mL (p=0.002) and functional outcome (p=0.007). Conclusion: In conclusion, no-reflow zones following successful AR were associated with infarct growth at all Tmax thresholds, however volume of residual Tmax &gt; 6 sec was independently associated with infarct growth &gt; 10 ml and poor functional outcome.

Abstract TMP85: Endovascular Thrombectomy for Large Ischemic Strokes With Tandem Lesions: A SELECT2 Subanalysis

Introduction: Trials evaluating thrombectomy (EVT) efficacy and safety in large vessel occlusion (LVO) excluded patients with cervical tandem lesions (TL). We aimed to evaluate EVT efficacy and safety in large stroke patients with TL from the SELECT2 trial. Methods: SELECT2 was a randomized controlled trial evaluating EVT vs. medical management (MM) in patients with LVO ischemic strokes (ASPECTS 3-5 on computed tomography (CT) or ischemic core ≥50 ml on CT Perfusion/MR diffusion-perfusion). TL were defined as internal carotid artery occlusion with a concomitant LVO as determined by the core lab. Functional, safety, and imaging outcomes were compared between patients in EVT vs. MM. Results: Of 352 enrolled, 100 (28%) had tandem occlusions, with 56 receiving EVT. ASPECTS (EVT: 4 [3-5] vs. MM: 4 [4-5]), ischemic core estimates (EVT: 86 [58-133] ml vs. MM: 81 [61-121] ml) and critically hypoperfused tissue volume (EVT: 185 [131-266] ml vs. MM: 192 [142-252] ml) were similar between groups. TL Patients receiving EVT demonstrated significantly better functional outcomes (mRS at 90d: EVT 4[3-6] vs MM 5[4-6]; aGenOR: 2.22; 95%CI, 1.47-3.34; p&lt;0.001), similar to those without TL (aGenOR: 1.59, 95% CI: 1.23-2.05, p&lt;0.001; P-int-0.29) and a higher proportion of patients achieving functional independence (EVT: 20% vs. MM: 2%; aRR: 9.53; 95%CI, 1.71-53.21; p=0.010) and independent ambulation (EVT: 38% vs MM: 11%; aRR: 3.60; 95%CI, 1.68-7.67; p=0.001), with significantly reduced complete dependence or death (mRS 5-6) (aRR: 0.66 (0.48-0.90), p=0.009). There was no difference in symptomatic ICH (EVT: 2% vs MM: 0%) or parenchymal hemorrhage (EVT: 2% vs MM: 0%). Complications occurred in 10 (18%) patients receiving EVT. In the EVT group, successful reperfusion (mTICI 2b-3) was associated with better functional outcome (aGenOR: 2.30; 95%CI, 1.14-4.65; p=0.021). Conclusion: In patients with tandem lesions, EVT and successful reperfusion were associated with better functional outcomes. Frequency of vascular complications was similar to those without tandem lesions and no patients receiving immediate stenting demonstrated parenchymal hemorrhage. Our findings support consideration of EVT in patients with tandem lesions with large ischemic strokes. NCT03876457

Abstract WP141: Leptomeningeal Competitive Flow Impact on Thrombectomy Reperfusion Grade Rating

Background: The extent of reperfusion following thrombectomy (MT) for large vessel occlusion strokes is predictive of outcomes. There is still inter-rater variability in the reperfusion scoring. We noticed that some patients present with retrograde contrast clearing of the distal branches from non-contrast-opacified flow originated from different territories. We aim to evaluate the frequency of this phenomenon (“competitive flow” (CF)), to evaluate if it has an association with the degree of leptomeningeal collaterals, and its impact on eTICI score. Methods: This is a retrospective-analysis of our MT database spanning 11/2020-12/2021. We included consecutive cases of intracranial internal carotid (i-ICA) and middle cerebral artery (MCA) M1 occlusions. CF was defined by the observation of retrograde clearing of distal MCA branches that were previously opacified by antegrade reperfusion. The clearance of the distal branches is presumed to occur due to CF via non-contrast-opacified PCA or ACA flow. The washout was considered CF if it cleared abruptly with or without forward reconstitution of antegrade opacification. Results: We included a 125 patients. Median age was 64years, 51%were males. Baseline median NIHSS was 17 and ASPECTS 9. Median last-known-well-time to puncture was 7 hours, 30.4% received tPA. Final eTICI2c-3 was achieved in 81.6%. CF was present in 32(25.6%)patients. Baseline characteristics were similar between both groups. The CF arm had better leptomeningeal single-phase-CTA-collaterals(p=0.01) and smaller CTP malignant hypoperfusion volume(p=0.06) VS non-CF. The inter-rater-agreement for eTICI score was moderate when CF was present and excellent in its absence (Krippendorf’s alpha=0.65 and 0.81,respectively). There was poor agreement (K-value=0.3) for the presence versus absence of CF between both operators. Reviewer 1 (2-year-post-training) had correctly identified 46% of patients with consensus CF vs 90% to Reviewer 2 (9-year-post-training) after the consensus read. Conclusion: CF was observed in 32% of patients. CF was found to be associated with better collateral flow, and to impact the reported procedural eTICI rating.

Abstract TP130: Prevalence of Fast Progressors of Infarct Growth in Anterior Circulation Large Vessel Occlusions &lt;6 Hours From Onset

Background/Purpose: Fast progressors (FP) of infarct growth in anterior circulation large vessel occlusions (LVO) may be prevalent in the &lt;6h period depending on how it is defined. The 3 recently completed randomized trials of endovascular thrombectomy (EVT) on large infarct core volumes (ICV) all used ASPECTS criterion of 3-5 which approximates 70-100mL in absolute volume. We aimed to investigate the prevalence of FP in LVO &lt;6h and how many of these were at or on pace to reach the 70mL or 100mL ICV threshold for EVT selection. Methods: We retrospectively included consecutive stroke patients arriving &lt;6h from symptom onset with ICA and/or M1 occlusion on CTA and had concurrent CT perfusion (CTP). RAPID AI software generated maps of ICV depicted as rCBF&lt;30% and critical hypoperfusion depicted as Tmax&gt;6s. Infarct growth rate (IGR) was calculated as ICV/onset-to-imaging time. FP was defined at 2 levels: as "FP70" with IGR &gt;11.7mL/h (which would result in an ICV &gt;70mL by 6h) and had &gt;=70mL of overall hypoperfusion present; and as "FP100" with IGR &gt;16.7mL/h (which would result in an ICV &gt;100mL by 6h) and had &gt;=100mL of overall hypoperfusion present. Results: 108 patients were included with median (IQR) age of 75.5 (67-85), NIHSS of 20 (12-24), onset time of 2h (1.5-4), median ICV of 11mL (0-40), hypoperfusion volume of 122mL (70-164), and mismatch volume of 86.5mL (58-130). The sites of LVO were ICA 12 (11.1%), M1 73 (67.6%), and both 23 (21.3%). Median IGR for the cohort was 3.8mL/h (0-16.4). 31 FP70 were found (28.7%, 95% CI: 19.5-40.7%) with median IGR of 31.3mL/h (16.8-42). 14 of these (45.2%, 95% CI: 24.7-75.8%) already had ICV&gt;70mL upon arrival, with median of 100mL (86-156) and 8 of 14 also showed mismatch ratio &lt;1.8. 25 FP100 were found (23.1%, 95% CI: 16.2-36.9%) with median IGR of 38.7mL/h (24.6-51.4). 8 of these (32.0%, 95% CI: 13.8-63.1%) already had ICV&gt;100mL upon arrival, with median of 138mL (101-172) and 5 of 8 also showed mismatch ratio &lt;1.8. Conclusion: In a cohort of acute anterior circulation LVO strokes &lt;6h from onset, the vast majority were good candidates for EVT with small to medium size core volumes. However, ~25% were fast progressors that may require more caution in selection, with ICV at or on pace to reach 70-100mL thresholds by 6h.

Prognostic value of CBV index in patients with acute ischemic stroke treated with endovascular thrombectomy in late therapeutic window.

To evaluate the prognostic value of the cerebral blood volume (CBV) index for 90-day functional outcomes in patients with acute ischemic stroke (AIS) treated within a late therapeutic window. We retrospectively reviewed patients who underwent pre-treatment computed tomography perfusion (CTP) and endovascular thrombectomy (EVT) for large-vessel occlusion (LVO) of the anterior circulation within the late therapeutic window between January 2021 and February 2023. Clinical data, the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) based on unenhanced computed tomography (CT), and perfusion parameters, including ischemic core, hypoperfusion volume, mismatch volume between the core and penumbra, and CBV index, were assessed and compared between patients who achieved favorable outcomes (defined as a modified Rankin Scale score of 0-2). Of the 118 patients, 56 (47.5%) had favorable outcomes. In the univariate analysis, age, National Institutes of Health Stroke Scale (NIHSS) score at admission, ASPECTS score, CBV index, and ischemic core volume were significantly associated with functional outcomes (P < 0.05). In multivariate analyses, age (odds ratio [OR], 1.060; 95% confidence interval [CI] 1.013-1.110, P = 0.012), NIHSS score at admission (OR, 1.126; 95% CI 1.031-1.229, P = 0.009), and CBV index (OR, 0.001; 95% CI 0.000-0.240, P = 0.014) were independent predictors of a 90-day favorable outcome. A high CBV index was independently associated with favorable outcomes in patients who underwent mechanical thrombectomy within the late therapeutic window. In addition, a higher CBV index reflects improved blood flow and favorable digital subtraction angiography collateral status.

Severely Hypoperfused Brain Tissue Correlates with Final Infarct Volume Despite Recanalization in DMVO Stroke.

We sought to assess whether there were any parameter(s) on baseline computed-tomography-perfusion (CTP) strongly correlating with final-infarct-volume, and infarct volume progression after endovascular recanalization of acute ischemic stroke (AIS) with primary distal, medium vessel occlusion (DMVO). We performed a retrospective analysis of consecutive AIS patients who were successfully recanalized by thrombectomy for DMVO. By comparing baseline CTP and follow-up MRI, we evaluated the correlation between baseline infarct and hypoperfusion volumes, and final infarct volume and infarct volume progression. We also examined their effect on good clinical outcome at 3 months (defined as an mRS score of 0 to 2). Between January 2018 and January 2021, 38 patients met the inclusion criteria (76% [29/38] female, median age 75 [66-86] years). Median final infarct volume and infarct volume progression were 8.4 mL [IQR: 5.2-44.4] and 7.2 mL [IQR: 4.3-29.1] respectively. TMax > 10 sec volume was strongly correlated with both (r = 0.831 and r = 0.771 respectively, p < 0.0001), as well as with good clinical outcome (-0.5, p = 0.001). A higher baseline TMax > 10 sec volume increased the probability of a higher final-infarct-volume (r2 = 0.690, coefficient = 0.83 [0.64-1.00], p < 0.0001), whereas it decreased the probability of good clinical outcome at 3 months (odds ratio = -0.67 [-1.17 to -0.18], p = 0.008). TMax > 10 sec volume on baseline CTP correlates strongly with final infarct volume as well as with clinical outcome after mechanical thrombectomy for an AIS with DMVO.

Automated advanced imaging in acute ischemic stroke. Certainties and uncertainties

The purpose of this is study was to review pearls and pitfalls of advanced imaging, such as computed tomography perfusion and diffusion-weighed imaging and perfusion-weighted imaging in the selection of acute ischemic stroke (AIS) patients suitable for endovascular treatment (EVT) in the late time window (6–24 h from symptom onset). Advanced imaging can quantify infarct core and ischemic penumbra using specific threshold values and provides optimal selection parameters, collectively called target mismatch. More precisely, target mismatch criteria consist of core volume and/or penumbra volume and mismatch ratio (the ratio between total hypoperfusion and core volumes) with precise cut-off values. The parameters of target mismatch are automatically calculated with dedicated software packages that allow a quick and standardized interpretation of advanced imaging. However, this approach has several limitations leading to a misclassification of core and penumbra volumes. In fact, automatic software platforms are affected by technical artifacts and are not interchangeable due to a remarkable vendor-dependent variability, resulting in different estimate of target mismatch parameters. In addition, advanced imaging is not completely accurate in detecting infarct core, that can be under- or overestimated. Finally, the selection of candidates for EVT remains currently suboptimal due to the high rates of futile reperfusion and overselection caused by the use of very stringent inclusion criteria. For these reasons, some investigators recently proposed to replace advanced with conventional imaging in the selection for EVT, after the demonstration that non-contrast CT ASPECTS and computed tomography angiography collateral evaluation are not inferior to advanced images in predicting outcome in AIS patients treated with EVT. However, other authors confirmed that CTP and PWI/DWI postprocessed images are superior to conventional imaging in establishing the eligibility of patients for EVT. Therefore, the routine application of automatic assessment of advanced imaging remains a matter of debate. Recent findings suggest that the combination of conventional and advanced imaging might improving our selection criteria.

Continued Infarction Growth and Penumbral Consumption After Reperfusion in Vaccine-Naïve Patients With COVID-19: A Case-Control Study.

Background: Neurologic sequelae of SARS-CoV-2 include potentially malignant cerebrovascular events arising from complex hemodynamic, hematologic, and inflammatory processes occurring in concert. Objective: This study concerns the hypothesis that, despite angiographic reperfusion, COVID-19 promotes continued consumption of at-risk tissue volumes after acute ischemic stroke (AIS) unlike what is seen with COVID-negative individuals, yielding critical insights into prognostication and monitoring paradigms in vaccine-naïve patients experiencing AIS. Methods: This retrospective study compared 100 consecutively presenting patients with COVID-19 and AIS between March 2020 and April 2021 with a contemporaneous cohort of 282 patients with AIS who did not have COVID-19. Reperfusion classes were dichotomized into positive (extended thrombolysis in cerebral ischemia [eTICI] score = 2c-3) and negative (eTICI score < 2c) groups. All patients underwent endovascular therapy following initial CT perfusion imaging (CTP) to document infarction core and total hypoperfusion volumes. Results: Ten COVID-positive (mean age ± SD, 67 ± 6 years; seven men, three women) and 144 COVID-negative patients (mean age, 71 ± 10 years; 76 men, 68 women) undergoing endovascular reperfusion with antecedent CTP and follow-up imaging comprised the final dataset. Initial infarction core and total hypoperfusion volumes were 1.5 ± 18 mL and 85 ± 100 mL in COVID-negative patients and 30.5 ± 34 mL and 117 ± 80.5 mL in COVID-positive patients, respectively. Final infarction volumes were significantly larger in patients with COVID-19, with median volumes of 77.8 mL versus 18.2 mL among control patients (p = .01), as were normalized measures of infarction growth relative to baseline infarction volume (p = .05). In adjusted logistic parametric regression models, COVID positivity emerged as a significant predictor for continued infarct growth (OR, 5.1 [95% CI, 1.0-25.95]; p = .05). Conclusion: These findings support the potentially aggressive clinical course of cerebrovascular events in patients with COVID-19, suggesting greater infarction growth and ongoing consumption of at-risk tissues, even following angiographic reperfusion. Clinical Impact: SARS-CoV-2 infection may promote continued infarction progression, despite angiographic reperfusion, in vaccine-naïve patients with large-vessel occlusion AIS. The findings carry potential implications for prognostication, treatment selection, and surveillance for infarction growth among revascularized patients in future waves of infection by novel viral strains.

ASPECTS-based net water uptake outperforms target mismatch for outcome prediction in patients with acute ischemic stroke and late therapeutic window.

To compare the prognostic value of net water uptake (NWU) and target mismatch (TM) on CT perfusion (CTP) in acute ischemic stroke (AIS) patients with late time window. One hundred and nine consecutive AIS patients with anterior-circulation large vessel occlusion presenting within 6-24 h from onset/last seen well were enrolled. Automated Alberta Stroke Program Early CT Score-based NWU (ASPECTS-NWU) was calculated from admission CT. The correlation between ASPECTS-NWU and CTP parameters was assessed. Predictors for favorable outcome (modified Rankin Scale score ≤ 2) at 90 days were assessed using logistic regression analysis. The ability of outcome prediction between ASPECTS-NWU and TM (an ischemic core < 70 mL, a mismatch ratio ≥ 1.8, and an absolute difference ≥ 15 mL) was compared using receiver operating characteristic (ROC) curve. A higher level of ASPECTS-NWU was associated with a larger ischemic core (r = 0.66, p < 0.001) and a larger hypoperfusion volume (r = 0.38, p < 0.001). ASPECTS-NWU performed better than TM for outcome stratification (area under the curve [AUC], 0.738 vs 0.583, p = 0.004) and was the only independent neuroimaging marker associated with favorable outcomes compared with CTP parameters (odds ratio, 0.73; 95% confidence interval [CI] 0.62-0.87, p < 0.001). An outcome prediction model including ASPECTS-NWU and clinical variables (National Institutes of Health Stroke Scale scores and age) yielded an AUC of 0.828 (95% CI 0.744-0.893; sensitivity 65.4%; specificity 87.7%). ASPECTS-NWU performed better than TM for outcome prediction in AIS patients with late time window and might be an alternative imaging biomarker to CTP for patient selection. Automated Alberta Stroke Program Early CT Score-based net water uptake outperforms target mismatch on CT perfusion for the outcome prediction in patients with acute ischemic stroke and can be an alternative imaging biomarker for patient selection in late therapeutic window. • A higher ASPECTS-based net water uptake was associated with larger ischemic cores and hypoperfusion volumes on CT perfusion. • ASPECTS-based net water uptake outperformed target mismatch for outcome prediction in acute ischemic stroke with extended therapeutic window. • ASPECTS-based net water uptake can be an alternative biomarkerto target mismatch for selecting acute ischemic stroke patients with late therapeutic window.

Comparison of Three Algorithms for Predicting Infarct Volume in Patients with Acute Ischemic Stroke by CT Perfusion Software: Bayesian, CSVD, and OSVD.

This study aimed to compare the performance of the Bayesian probabilistic method, circular Singular Value Decomposition (cSVD), and oscillation index Singular Value Decomposition (oSVD) algorithms in Olea Sphere for predicting infarct volume in patients with acute ischemic stroke (AIS). Eighty-seven patients suffering from AIS with large vessel occlusion were divided into improvement and progression groups. The improvement group included patients with successful recanalization (TICI 2b-3) after thrombectomy or whose clinical symptoms improved after thrombolysis. The progression group consisted of patients whose clinical symptoms did not improve or even got worse. The infarct core volume from the Olea Sphere software was used as the predicted infarct volume (PIV) in the improvement group, whereas the hypoperfusion volume was used as the PIV in the progression group. We defined predicted difference (PD) as PIV minus final infarct volume (FIV) measured at follow-up imaging. Differences among the three algorithms were assessed by the Friedman test. Spearman correlation analysis was used to verify the correlation between PIV and FIV. In addition, we performed a subgroup analysis of the progression group based on collateral circulation status. The median [interquartile range (IQR)] of the PD and Spearman correlation coefficients (SCCs) between PIV and FIV for the improvement group (n = 22) were: Bayesian = [6.99 (-14.72, 18.99), 0.500]; oSVD = [-12.74 (-41.06, -3.46), 0.423]; cSVD = [-15.38 (-38.92, -4.68), 0.586]. For the progression group (n = 65), the median (IQR) of PD and SCCs were: Bayesian = [1.00 (-34.07, 49.37), 0.748]; oSVD = [-0.17 (-53.42, 29.73), 0.712]; cSVD = [66.55 (7.94, 106.32), 0.674]. The Bayesian algorithm in the Olea Sphere software predicted infarct volumes with better accuracy and stability than the other two algorithms in both the progression and improvement groups.

Efficacy and Safety of Injection Tenecteplase in 4.5 to 24 hours imaging eligible window patients with Acute Ischemic Stroke (EAST-AIS) (P7-5.016)

<h3>Objective:</h3> To determine the efficacy and safety of injection Tenecteplase along with standard treatment in acute ischemic stroke with or without large vessel occlusion presenting within 4.5 to 24 hours of onset <h3>Background:</h3> Currently in Acute Ischemic stroke (AIS) patients, intravenous thrombolysis is approved for the 0-to-4.5-hour window period and mechanical thrombectomy for large vessel occlusion up to 24 hours of stroke onset in eligible patients. Previous studies have evaluated the safety and efficacy of Tenectplasse in a small number of patients in the period beyond 4.5hours of stroke onset. In the present study, we evaluate the safety and efficacy of injction of Tenectplase in AIS patients (with or without large vessel occlusion) in the time window 4.5 to 24 hours of stroke onset. <h3>Design/Methods:</h3> Patients will be enrolled primarily based on imaging the eligibility criteria with a perfusion lesion-ischemic core mismatch greater than1.8 between the volume of hypoperfusion and the volume of the ischemic core, with the absolute difference in volume being greater than 10 ml, and ischemic-core volume less than 70 ml. Additional inclusion criteria are patients age should be &gt; 18 years, onset period between 4.5 to 24 hours with NIHSS&gt;5, and pre-stroke Mrs value of 2 or less. A total of one hundred patients are planned to be enrolled, 50 each in Tenectlase are (cases-0.25mg/kg; maximum 25mg) and placebo arm (controls) in a ratio of 1:1 administered as a singlr bolus injection. An independent data safety and monitoring board (DSMB) will share responsibility for regular oversight of patient safety during the study. <h3>Results:</h3> This is ongoing randomized control trial. <h3>Conclusions:</h3> The study is an investigator initiated prospective and randomized controlled trial design. The safety endpoints along with efficacy of Tenecteplase using the modified Ranking Scale (mRS) score at 90 days of stroke onset will be determined. <b>Disclosure:</b> Dr. Jatwani has nothing to disclose. Awadh K. Pandit has nothing to disclose. Ms. Tangri has nothing to disclose. Dr. Srivastava has nothing to disclose. Dr. Bhatia has nothing to disclose. Ajay Garg has nothing to disclose. Dr. Vibha has nothing to disclose. Vishnu VY has nothing to disclose. Dr. Das has nothing to disclose. Divya MR has nothing to disclose.

Comparison of two computed tomography perfusion post-processing software to assess infarct volume in patients with acute ischemic stroke.

We used two automated software commonly employed in clinical practice-Olea Sphere (Olea) and Shukun-PerfusionGo (PerfusionGo)-to compare the diagnostic utility and volumetric agreement of computed tomography perfusion (CTP)-predicted final infarct volume (FIV) with true FIV in patients with anterior-circulation acute ischemic stroke (AIS). In all, 122 patients with anterior-circulation AIS who met the inclusion and exclusion criteria were retrospectively enrolled and divided into two groups: intervention group (n = 52) and conservative group (n = 70), according to recanalization of blood vessels and clinical outcome (NIHSS) after different treatments. Patients in both groups underwent one-stop 4D-CT angiography (CTA)/CTP, and the raw CTP data were processed on a workstation using Olea and PerfusionGo post-processing software, to calculate and obtain the ischemic core (IC) and hypoperfusion (IC plus penumbra) volumes, hypoperfusion in the conservative group and IC in the intervention group were used to define the predicted FIV. The ITK-SNAP software was used to manually outline and measure true FIV on the follow-up non-enhanced CT or MRI-DWI images. Intraclass correlation coefficients (ICC), Bland-Altman, and Kappa analysis were used to compare the differences in IC and penumbra volumes calculated by the Olea and PerfusionGo software to investigate the relationship between their predicted FIV and true FIV. The IC and penumbra difference between Olea and PerfusionGo within the same group (p < 0.001) was statistically significant. Olea obtained larger IC and smaller penumbra than PerfusionGo. Both software partially overestimated the infarct volume, but Olea significantly overestimated it by a larger percentage. ICC analysis showed that Olea performed better than PerfusionGo (intervention-Olea: ICC 0.633, 95%CI 0.439-0.771; intervention-PerfusionGo: ICC 0.526, 95%CI 0.299-0.696; conservative-Olea: ICC 0.623, 95%CI 0.457-0.747; conservative-PerfusionGo: ICC 0.507, 95%CI 0.312-0.662). Olea and PerfusionGo had the same capacity in accurately diagnosing and classifying patients with infarct volume <70 ml. Both software had differences in the evaluation of the IC and penumbra. Olea's predicted FIV was more closely correlated with the true FIV than PerfusionGo's prediction. Accurate assessment of infarction on CTP post-processing software remains challenging. Our results may have important practice implications for the clinical use of perfusion post-processing software.

Multidelay Arterial Spin Labeling Versus Computed Tomography Perfusion in Penumbra Volume of Acute Ischemic Stroke.

Multidelay arterial spin labeling (ASL) is a novel perfusion method of ASL, with arterial transit time (ATT) calculated by multiple postlabeling delays to correct cerebral blood flow (CBF). We verify the accuracy of multidelay ASL in evaluating the ischemic penumbra and perfusion levels in patients with acute ischemic stroke, compared with computed tomography perfusion (CTP). Patients with acute ischemic stroke with anterior circulation large vessel occlusion received baseline CTP, multidelay ASL, and diffusion-weighted imaging (DWI) in succession. Multidelay ASL image was processed to reconstruct ATT, CBF without ATT correction, and CBF corrected by ATT. The consistency of hypoperfusion and ischemic penumbra volume calculated by CTP and multidelay ASL were quantified by intraclass correlation coefficient (ICC) in 2-way mixed effects, absolute agreement, and single measure. Wilcoxon signed-rank test was used to compare the difference in penumbra volume between CTP, corrected ASL, and uncorrected ASL. Thirty patients were included. Hypoperfusion volume based on multidelay ASL with different thresholds were 117.95 (87.77-151.49) mL for corrected relative CBF<40%, 130.29 (85.99-249.37) mL for CBF corrected by ATT<20 mL·100g-1·min-1, no statistical difference (P>0.05) compared with the volume of CTP, and consistency was almost excellent (ICC, 0.91) and substantial consistent (ICC, 0.727). The volumes of ischemic penumbra were 91.00 (42.68-125.27) mL for corrected relative CBF<40%-DWI, 108.94 (62.03-150.86) mL for CBF corrected by ATT<20 mL·100 g-1·min-1-DWI, which showed no statistical difference compared with the penumbra volume of CTP (P>0.05). The consistency was excellent (ICC, 0.822) and moderate (ICC, 0.501), respectively. The volume of uncorrected relative CBF <40%-DWI was 209.57 (123.21-292.45) mL, statistically larger than corrected relative CBF <40%-DWI (P<0.001) and CTP (P<0.001). The volume of uncorrected CBF<20 mL·100g-1·min-1-DWI was 186.23 (86.56-298.22) mL, statistically larger than CBF corrected by ATT<20 mL·100g-1·min-1-DWI (P<0.001) and CTP(P<0.001). The volume of ischemic penumbra determined by CBF/DWI mismatch based on multidelay ASL is consistent with CTP. The penumbra volume calculated by CBF adjusted by ATT is more accurate.

Comparison of 3 CT Perfusion Software Packages in Estimation of Ischemic Lesions in Acute Ischemic Stroke Patients.

The aim of this study was to compare 3 computed tomography perfusion (CTP) software packages in the estimation of infarct core volumes, hypoperfusion volumes, and mismatch volumes. Forty-three patients with large vessel occlusion in the anterior circulation who underwent CTP imaging were postprocessed by 3 software packages: RAPID, advantage workstation (AW), and NovoStroke Kit (NSK). Infarct core volumes and hypoperfusion volumes were generated by RAPID with default settings. The AW and NSK threshold settings were the following: infarct core (cerebral blood flow [CBF] <8 mL/min/100 g, CBF <10 mL/min/100 g, CBF <12 mL/min/100 g, and cerebral blood volume [CBV] <1 mL/100 g) and hypoperfusion (Tmax >6 seconds). Mismatch volumes were then obtained for all the combinations of the settings. Bland-Altman, intraclass correlation coefficient (ICC), and Spearman ρ or Pearson correlation coefficient were applied for statistical analysis. In the estimation of infarct core volumes, good agreement was observed between AW and RAPID when CBV <1 mL/100 g (ICC, 0.767; P < 0.001). For hypoperfusion volumes, good agreement (ICC, 0.811; P < 0.001) and strong correlation (r = 0.856; P < 0.001) were observed between NSK and RAPID. For mismatch volumes, the setting of CBF <10 mL/min/100 g combined with hypoperfusion with NSK resulted in moderate agreement (ICC, 0.699; P < 0.001) with RAPID, which was the best among all other settings. The estimation results varied among different software packages. Advantage workstation had the best agreement with RAPID in the estimation of infarct core volumes when CBV <1 mL/100 g. NovoStroke Kit had better agreement and correlation with RAPID in the estimation of hypoperfusion volumes. NovoStroke Kit also had moderate agreement with RAPID in estimating mismatch volumes.

Abstract Number ‐ 241: Simultaneous IV tPA During Thrombectomy Reduces Post‐Procedure Hypoperfusion Volumes in Anterior LVO Patients

Introduction Simultaneous tPA administration during mechanical thrombectomy may induce synergistic benefits (1). We aimed to characterize the hypoperfusion status after thrombectomy according to the timing of tPA administration and the degree of final recanalization. Methods We studied consecutive anterior circulation large vessel occlusion (LVO) stroke patients treated with mechanical thrombectomy who received a CT perfusion (CTP) immediately after endovascular procedure (2). Patients were divided in three groups according to: no iv tPA treatment (non‐tPA), tPA administration before 120 minutes (tPA&gt;120) or iv tPA administration within 120 min (tPA&lt; 120) of groin puncture. The extend of post‐procedure hypoperfusion (volume Tmax&gt;6s) and relative hypoperfusion reduction compared with admission CTP (volume post‐procedure – admission Tmax&gt;6s/admission Tmax&gt;6s) according to final TICI scores were compared between the three study groups. Results One hundred and sixty‐nine patients were included in the study, mean age 72 years and median baseline NIHSS of 15. Thirty (17.8%) patients received iv tPA more than 2h before groin puncture (tPA&gt;120), 32(18.9%) within 2h of the puncture (tPA &lt; 120) and 107(63.3%) were non‐tPA. No difference on stroke severity, pre‐procedure hypoperfusion volume or occlusion location before thrombectomy were detected between groups. The rate of complete recanalization (TICI 3, 38.5%) was also similar in the 3 study groups (p = 0.12). Overall, the post‐procedure hypoperfusion volume was significantly lower in the tPA&lt; 120 group (19.9±4.6cc vs 35.0±5.5, p = 0.04), and the relative hypoperfusion reduction was higher in tPA&lt; 120 (0.86 vs 0.66, p = 0.05) as compared to non‐tPA. No significant differences were detected between non‐tPA and tPA&gt;120 groups. For each final TICI score the post‐procedure hypoperfusion tended to be lower in the tPA&lt; 120‐group, with a stronger reduction in patients with lower degree of recanalization (Figure). Conclusions A reduction of post‐thrombectomy hypoperfusion volumes was detected in patients treated with iv tPA during or shortly before thrombectomy, which could be a surrogate marker of the beneficial effect of tPA on the microcirculation. The specific reperfusion synergistic effect of tPA and mechanical thrombectomy beyond LVO recanalization warrants future studies.