Cortical Vein Opacification for Risk Stratification in Anterior Circulation Endovascular Thrombectomy

Simplifying venous outflow: Prolonged venous transit as a novel qualitative marker correlating with acute stroke outcomes

BACKGROUND

Prolonged venous transit (PVT), defined as presence of time-to-maximum ≥ 10 s within the superior sagittal sinus (SSS) and/or torcula, is a novel, qualitatively assessed computed tomography perfusion surrogate parameter of venous outflow with potential utility in pretreatment acute ischemic stroke imaging for neuroprognostication. We aim to characterize the correlation between PVT and neurological functional outcomes in thrombectomy-treated patients.

METHODS

A prospectively-collected database of large vessel occlusion acute ischemic stroke patients treated with thrombectomy was retrospectively analyzed. Spearman's rank correlation coefficient and point-biserial correlations were performed between PVT status (i.e., no region, either SSS or torcula, or both), 90-day modified Rankin score (mRS), mortality (mRS 6), and poor functional outcome (mRS 4-6 vs 0-3).

RESULTS

Of 128 patients, correlation between PVT and 90-day mRS (ρ = 0.35, p < 0.0001), mortality (r = 0.26, p = 0.002), and poor functional outcome (r = 0.27, p = 0.002) were significant.

CONCLUSION

There is a modest, significant correlation between PVT and severity of neurological functional outcome. Consequently, PVT is an easily-ascertained, qualitative metric that may be useful as an adjunct for anticipating a patient's clinical course. Future analyses will determine the significance of incorporating PVT in clinical decision-making.

The benefit of favorable venous outflow profiles is mediated through the reduced risk of intracranial hemorrhage in acute ischemic stroke patients undergoing endovascular treatment

BACKGROUND

Favorable venous outflow (VO) has been recognized as an independent predictor of excellent clinical outcomes in acute ischemic stroke caused by anterior circulation large vessel occlusion (AIS-LVO) patients who received endovascular treatment (EVT). However, the reasons why VO affects clinical outcomes have not been fully explained. In this study, we aimed to identify the potential mediators of VO affecting prognosis.

METHODS

We conducted a multicenter retrospective cohort study of consecutive patients with AIS-LVO who underwent EVT. Baseline computed tomographic angiography (CTA) was applied to assess VO by the Cortical Vein Opacification Score (COVES). The primary outcome was functional independence at 90 days (modified Rankin Scale (mRS) score of 0-2). Classifying subtypes of intracranial hemorrhage (ICH) to explore the relationship between ICH subtypes and VO. Multivariate logistic regression and causal mediation analyses were used to evaluate the relationship among VO, functional independence, and potential mediators.

RESULTS

Among 860 AIS-LVO patients undergoing EVT, a total of 515 patients were included in the present study after strict screening. In multivariate logistic regression analysis, favorable VO profiles (defined as COVES 3-6) were significantly associated with a lower incidence of ICH (24.2% vs 46.9%, adjusted odds ratio (aOR) 0.48, 95% confidence interval (CI) 0.30 to 0.77, P=0.002) and a higher proportion of functional independence (58.9% vs 15.0%, aOR 4.07, 95% CI 2.41 to 6.88, P<0.001). Mediation analysis showed that favorable VO profiles significantly reduced the incidence of parencuymal hematoma (PH) 2 accounting for 8.0% (95% CI 0.9% to 19.0%) of its beneficial effect on functional independence.

CONCLUSION

This study demonstrated the potential mediating effects of severe ICH for the beneficial effect of favorable VO on clinical prognosis among patients with AIS-LVO who underwent EVT.

Colour-coded collateral and venous outflow patterns in estimating infarct progression and predicting functional independence for stroke patients in late time window

OBJECTIVES

To investigate whether cerebral collateral and venous outflow (VO) patterns on colour-coded multi-phase computed tomography angiography (mCTA) can estimate ischaemic core growth rate (IGR) and predict 90-day functional independence for patients with late-presenting acute ischaemic stroke (AIS).

METHODS

The retrospective analysis included 127 AIS patients with a late time window. All patients underwent baseline mCTA with colour-coded reconstruction and computed tomography perfusion. Both collateral score and VO score on colour-coded mCTA maps were analysed and recorded. The IGR was calculated as ischaemic core volume divided by the time from onset to imaging. A 90-day modified Rankin Scale score of 0-2 was defined as functional independence. Kendall's Tau-b analysis was used for nonparametric correlation analysis. Propensity scores, logistic regressions, and receiver operator characteristic (ROC) curves were applied to construct the prediction model.

RESULTS

Moderate correlations were found between collateral delay and IGR (Tau-b = -0.554) and between VO and IGR (Tau-b = -0.501). High collateral score (odds ratio = 3.01) and adequate VO (odds ratio = 4.89) remained independent predictors for 90-day functional independence after adjustment. The joint predictive model, which integrated the VO score and clinical features, demonstrated an area under the ROC curve (AUC) of 0.878. The AUCs of collateral score and VO score were 0.836 and 0.883 for outcome prediction after adjustment.

CONCLUSIONS

Cerebral collateral and VO patterns based on colour-coded mCTA can effectively predict infarct progression and 90-day clinical outcomes, even for AIS patients beyond the routine time window.

ADVANCES IN KNOWLEDGE

Colour-coded mCTA is a readily understandable post-processing technique for the rapid assessment of collateral circulation and VO status in stroke imaging. A moderate correlation was observed between the characteristics of collateral delay/VO on colour-coded mCTA and IGR in patients with AIS. Both high-quality collateral circulation and "red superficial middle cerebral vein sign" can predict 90-day functional independence even for patients beyond the routine time window.

Early neurological deterioration in patients with acute ischemic stroke is linked to unfavorable cerebral venous outflow

INTRODUCTION

Early neurological deterioration (END) is associated with poor outcomes in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). Causes of END after mechanical thrombectomy (MT) include unsuccessful recanalization and reperfusion hemorrhages. However, little is known about END excluding the aforementioned causes. We aimed to investigate factors associated with unexplained END (ENDunexplained) with regard to the cerebral collateral status.

PATIENTS AND METHODS

Multicenter retrospective study of AIS-LVO patients with successful MT (mTICI 2b-3). On admission CT angiography (CTA), pial arterial collaterals and venous outflow (VO) were assessed using the modified Tan-Scale and the Cortical Vein Opacification Score (COVES), respectively. ENDunexplained was defined as an increase in NIHSS score of ⩾ 4 within the first 24 hours after MT without parenchymal hemorrhage on follow-up imaging. Multivariable regression analyses were performed to examine factors of ENDunexplained and unfavorable functional outcome (modified Rankin Scale score 3-6).

RESULTS

A total of 620 patients met the inclusion criteria. ENDunexplained occurred in 10% of patients. While there was no significant difference in pial arterial collaterals, patients with ENDunexplained exhibited more often unfavorable VO (81% vs. 53%; P < 0.001). Unfavorable VO (aOR [95% CI]; 2.56 [1.02-6.40]; P = 0.045) was an independent predictor of ENDunexplained. ENDunexplained was independently associated with unfavorable functional outcomes at 90 days (aOR [95% CI]; 6.25 [2.06-18.94]; P = 0.001).

DISCUSSION AND CONCLUSION

Unfavorable VO on admission CTA was associated with ENDunexplained. ENDunexplained was independently linked to unfavorable functional outcomes at 90 days. Identifying AIS-LVO patients at risk of ENDunexplained may help to select patients for intensified monitoring and guide to optimal treatment regimes.

Microvascular dysfunction associated with unfavorable venous outflow in acute ischemic stroke patients

Unfavorable venous outflow (VO) is associated with cerebral edema, which represents microvascular dysfunction. This study estimated the relationship between VO and microvascular function in acute ischemic stroke patients. We retrospectively included 102 MCA/ICA occluded patients with anterior circulation infarction who underwent reperfusion therapy between July 2017 and April 2022. Unfavorable VO was defined as a cortical vein opacification score of 0-3 and favorable VO as that of 4-6. The clinical characteristics, collateral status, microvascular integrity, and outcomes were compared between patients with favorable and unfavorable VO. Multivariate analysis and receiver operator characteristic (ROC) analysis were used. The patients with unfavorable VO had higher extravascular-extracellular volume fraction (Ve) in the infarct core and a lower percentage of robust arterial collateral circulation. ROC analysis revealed that Ve in the infarct core predicts unfavorable VO (AUC = 0.67, sensitivity = 65.08%, specificity = 69.23%). The higher Ve in the infarct core (odds ratio = 1.011, 95% CI = 1.000-1.021, P = 0.046) and poor arterial collateral flow (odds ratio = 0.102, 95% CI = 0.032-0.327, P < 0.001) were independent predictors of unfavorable VO. This suggests that microvascular dysfunction may be one of the mechanisms underlying impaired VO.

Automatic cerebral computed tomography venographic imaging based on the prior knowledge of cerebral blood circulation

BACKGROUND AND PURPOSE

Current clinical computed tomography venographic (cCTV) images present limited cerebral venous profiles. Therefore, this study aimed to develop an automatic cerebral CTV imaging technique using computed tomographic perfusion (CTP) images in a cohort of patients with stroke.

MATERIALS AND METHODS

We retrospectively evaluated 10 (intracerebral hemorrhage) and 2 (acute ischemic stroke) patients who underwent institutional CTP imaging. CTV images were processed with the proposed CTV (pCTV) technique, and pCTV and cCTV images were then independently evaluated by two experienced neuroradiologists blinded to all clinical information using a novel scoring method that considered overall image quality, venous visibility, and arterial mis-segmentation. Venous visibility was separately evaluated for the dural sinus, superficial vein, and deep vein. Then, statistical analysis was performed to determine whether the pCTV technique was superior to the cCTV technique.

RESULTS

In total, 14 sets of pCTV images were generated and compared with cCTV images. The overall image quality and venous visibility scores of pCTV images were significantly higher than those of cCTV images (all values of p<0.05), especially for the dural sinus (median [25th, 75th percentiles], 14.00 [13.63, 15.50] vs. 7.50 [7.00, 10.88]), and superficial vein (9.00 [8.88, 10.00] vs. 3.25 [1.63, 8.25]), while the difference in arterial mis-segmentation was not statistically significant (p= 0.164).

CONCLUSIONS

This study proposed an automatic cerebral CTV imaging technique to eliminate residual bone and soft tissues, minimize the impact of the cerebral arterial system, and present a relatively comprehensive cerebral venous system, which would help physicians assess cerebral venous outflow profiles after stroke and seek imaging markers associated with clinical outcomes.

Decrease in cortical vein opacification predicts outcome after aneurysmal subarachnoid hemorrhage

BACKGROUND

The pathophysiology of brain injury after aneurysmal subarachnoid hemorrhage (aSAH) remains incompletely understood. Cerebral venous flow patterns may be a marker of hemodynamic disruptions after aneurysm rupture. We hypothesized that a decrease in venous filling after aSAH would predict cerebral ischemia and poor outcome.

OBJECTIVE

To examine the hypotheses that venous filling as measured by the cortical venous opacification score (COVES) would (1) decrease after aSAH and (2) that decreased COVES would be associated with higher rates of hydrocephalus, vasospasm, delayed cerebral iscemia (DCI), and poor functional evaluation at outcome.

METHODS

In this retrospective observational cohort study of consecutive patients with aSAH admitted to our tertiary care center between 2016 and 2018, we measured the COVES at admission and at subsequent CT angiography (CTA). We collected clinical variables and compared hydrocephalus, vasospasm, DCI, and outcome at discharge in patients with decrease in COVES with patients with stable COVES.

RESULTS

A total of 22 patients were included in the analysis. COVES decreased from first CTA to second CTA in 11 (50%) patients, by an average of 1.1 points (P=0.01). Patients whose COVES decreased between admission and follow-up imaging were more likely to develop DCI (58% vs 0%, P=0.03) and have a poor outcome at discharge (100% vs 55%, P=0.03) than patients who had no change in COVES. aSAH severity was not associated with initial COVES, and there was no association between change in COVES and development of hydrocephalus or vasospasm.

CONCLUSIONS

Development of decreased venous filling on CTA is associated with poor outcome after aSAH. This association suggests that venous hemodynamics may be reflective of, or contribute to, the pathophysiological mechanisms of brain injury after aSAH. Larger prospective studies are necessary to substantiate our findings.

The negative effect of aging on cerebral venous outflow in acute ischemic stroke

Cortical venous outflow (VO) represents an imaging biomarker of increasing interest in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). We conducted a retrospective multicenter cohort study to investigate the effect of aging on VO. A total of 784 patients met the inclusion criteria. Cortical Vein Opacification Score (COVES) was used to assess VO profiles on admission CT angiography. Cerebral microperfusion was determined using the hypoperfusion intensity ratio (HIR) derived from perfusion imaging. Arterial collaterals were assessed using the Tan scale. Multivariable regression analysis was performed to identify independent determinants of VO, HIR and arterial collaterals. In multivariable regression, higher age correlated with worse VO (adjusted odds ratio [95% CI]; 0.83 [0.73-0.95]; P = 0.006) and poorer HIR (β coefficient [95% CI], 0.014 [0.005-0.024]; P = 0.002). The negative effect of higher age on VO was mediated by the extent of HIR (17.3%). We conclude that higher age was associated with worse VO in AIS-LVO, partially explained by the extent of HIR reflecting cerebral microperfusion. Our study underlines the need to assess collateral blood flow beyond the arterial system and provides valuable insights into deteriorated cerebral blood supply in elderly AIS-LVO patients.

Prognostic Value of Venous Outflow Profiles on Multiphase CT Angiography for the Patients with Acute Ischemic Stroke After Endovascular Thrombectomy

To evaluate the prognostic value of venous outflow (VO) profiles evaluated on multiphase CTA (mCTA) for the patients with acute ischemic stroke (AIS) after endovascular thrombectomy (EVT). We retrospectively collected 150 patients with AIS who underwent pre-treatment CT perfusion (CTP) evaluation and subsequent EVT from April 2018 to April 2022. Three-phases (peak arterial phase, peak venous phase, late venous phase) CTA was reconstructed from CTP raw data, and VO was evaluated on three-phases CTA, respectively. Favorable VO was regarded as a cortical vein opacification score of 3-6, and unfavorable VO as a score of 0-2. Good outcome was defined as modified Rankin Scale score of 0-2 at 90 days after EVT. Multivariate logistic regression analysis was performed to explore the predictors of good outcome. Prognostic value was assessed and compared using receiver operating characteristic (ROC) curves and Delong test. We found that good outcome was achieved in 85 (56.7%) patients. Among the mCTA-derived VO profiles, only favorable peak venous phase VO was found to be independently associated with good outcome (P < 0.001). After integrating favorable peak venous phase VO with lower post-treatment National Institute of Health Stroke Scale score at 24 hours, successful recanalization and favorable hypoperfusion intensity ratio, the predictive ability for a good outcome was significantly improved than before (area under the ROC curve; 0.947 vs 0.881; P = 0.002). This study supports that favorable peak venous VO profiles on mCTA might be a promising biomarker in predicting the good outcome in patients with AIS after EVT.

Significant Slowed Cortical Venous Blood Flow in Patients with Acute Ischemic Stroke with Large Vessel Occlusion Suggests Poor Collateral Circulation and Prognosis

RATIONALE AND OBJECTIVES

To investigate the change of cortical venous flow in acute ischemic stroke patients with large vessel occlusion (LVO-AIS) and its clinical value.

MATERIALS AND METHODS

Baseline whole-brain 4D-CTA/CTP and clinical data of LVO-AIS and a control group were collected from June 2020 to October 2021. Venous inflow time (VIT), venous peak time (VPT), and venous outflow time (VOT) were analyzed on both sides of patients and normal controls. The VIT/VPT/VOT were statistically described and compared between the patient group and normal controls, then, in patients with different collateral circulation and prognoses. Next, the correlation between cortical venous drainage time and collateral circulation grading was analyzed. Finally, logistic regression analysis was used to explore the relationship between the three venous times and prognosis, and receiver operating characteristic (ROC) curves were plotted to assess the value of delayed cortical venous imaging in predicting prognosis.

RESULTS

149 LVO-AIS and 73 normal controls were collected. VIT, VPT, and VOT were significantly delayed on the affected side in the patient group compared with the healthy side (p<0.05) and the controls (p<0.05); VIT and VPT were also significantly delayed on the healthy side of patients compared with the controls (p<0.05). Delayed VIT and VPT on the affected side in the patient group were more significant in patients with poor collateral circulation (p<0.05), and VIT and VPT on the affected side in the patient group were negatively correlated with arterial collateral scores. VIT and VPT were significantly delayed in both sides of patients in the poor prognosis group compared with the good prognosis group (p<0.05). logistic regression showed that patients' affected VPT, arterial collateral scores, and NIHSS were independent predictors of poor prognosis, with an accuracy of 79.6% in predicting poor prognosis. The affected VPT and NIHSS were independent predictors of poor prognosis for patients presenting within 24 hours, with an accuracy of 79.6% in predicting poor prognosis.

CONCLUSION

Cortical venous flow was significantly slowed in both sides of LVO-AIS patients. delayed ipsilateral VPT in LVO-AIS patients can be used as an imaging indicator to determine poor collateral circulation and predict poor prognosis.

Unfavorable cerebral venous outflow is associated with futile recanalization in acute ischemic stroke patients

BACKGROUND AND PURPOSE

Mechanical thrombectomy (MT) has proven to be the standard of care for patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). However, high revascularization rates do not necessarily result in favorable functional outcomes. We aimed to investigate imaging biomarkers associated with futile recanalization, defined as unfavorable functional outcome despite successful recanalization in AIS-LVO patients.

METHODS

A retrospective multicenter cohort study was made of AIS-LVO patients treated by MT. Successful recanalization was defined as modified Thrombolysis in Cerebral Infarction score of 2b-3. A modified Rankin Scale score of 3-6 at 90 days was defined as unfavorable functional outcome. Cortical Vein Opacification Score (COVES) was used to assess venous outflow (VO), and the Tan scale was utilized to determine pial arterial collaterals on admission computed tomography angiography (CTA). Unfavorable VO was defined as COVES ≤ 2. Multivariable regression analysis was performed to investigate vascular imaging factors associated with futile recanalization.

RESULTS

Among 539 patients in whom successful recanalization was achieved, unfavorable functional outcome was observed in 59% of patients. Fifty-eight percent of patients had unfavorable VO, and 31% exhibited poor pial arterial collaterals. In multivariable regression, unfavorable VO was a strong predictor (adjusted odds ratio = 4.79, 95% confidence interval = 2.48-9.23) of unfavorable functional outcome despite successful recanalization.

CONCLUSIONS

We observe that unfavorable VO on admission CTA is a strong predictor of unfavorable functional outcomes despite successful vessel recanalization in AIS-LVO patients. Assessment of VO profiles could help as a pretreatment imaging biomarker to determine patients at risk for futile recanalization.

CT perfusion to measure venous outflow in acute ischemic stroke in patients with a large vessel occlusion

BACKGROUND

Robust venous outflow (VO) profiles, measured by degree of venous opacification on pre-thrombectomy CT angiography (CTA) studies, are strongly correlated with favorable outcomes in patients with large vessel occlusion acute ischemic stroke treated by thrombectomy. However, VO measurements are laborious and require neuroimaging expertise.

OBJECTIVE

To develop a semi-automated method to measure VO using CTA and CT perfusion imaging studies.

METHODS

We developed a graphical interface using The Visualization Toolkit, allowing for voxel selection at the confluence and bilateral internal cerebral veins on CTA along with arterial input functions (AIFs) from both internal carotid arteries. We extracted concentration-time curves from the CT perfusion study at the corresponding locations associated with AIF and venous output function (VOF). Outcome analyses were primarily conducted by the Mann-Whitney U and Jonckheere-Terpstra tests.

RESULTS

Segmentation at the pre-selected AIF and VOF locations was performed on a sample of 97 patients. 65 patients had favorable VO (VO+) and 32 patients had unfavorable VO (VO-). VO+ patients were found to have a significantly shorter VOF time to peak (8.26; 95% CI 7.07 to 10.34) than VO- patients (9.44; 95% CI 8.61 to 10.91), P=0.007. No significant difference was found in VOF curve width and the difference in time between AIF and VOF peaks.

CONCLUSIONS

Time to peak of VOF at the confluence of sinuses was significantly associated with manually scored venous outflow. Further studies should aim to understand better the association between arterial inflow and venous outflow, and capture quantitative metrics of venous outflow at other locations.

Association of intravascular enhancement sign detected on high-resolution vessel wall imaging with ischaemic events in middle cerebral artery occlusion

PURPOSE

Patients with intracranial artery occlusion have high rates of ischaemic events and recurrence. Early identification of patients with high-risk factors is therefore beneficial for prevention. Here we assessed the association between the intravascular enhancement sign (IVES) on high-resolution vessel wall imaging (HR-VWI) and acute ischaemic stroke (AIS) in a population with middle cerebral artery (MCA) occlusion.

METHOD

We retrospectively analysed the records of 106 patients with 111 MCA occlusions, including 60 with and 51 without AIS, who had undergone HR-VWI and computed tomography angiography (CTA) examinations from November 2016 to February 2023. Numbers of IVES vessels were counted and compared to the CTA findings. Statistical analyses of demographic and medical data were also performed.

RESULTS

Occurrence rates and numbers of IVES vessels were significantly higher in the AIS than the non-AIS group (P < 0.05), and most vessels were detected on CTA. Numbers of vessels positively correlated with AIS occurrence (rho = 0.664; P < 0.0001). A multivariable ordinal logistic regression model adjusted for age, degree of wall enhancement, hypertension, and heart status identified the number of IVES vessels as an independent predictor for AIS (odds ratio = 1.6; 95% CI, 1.3-1.9; P < 0.0001).

CONCLUSION

Number of IVES vessels is an independent risk factor for AIS events, and may represent poor cerebral blood flow status and collateral compensation level. It thus provides cerebral haemodynamic information for patients with MCA occlusion for clinical use.

Comprehensive Venous Outflow Predicts Functional Outcomes in Patients with Acute Ischemic Stroke Treated by Thrombectomy

BACKGROUND AND PURPOSE

Cortical venous outflow has emerged as a robust measure of collateral blood flow in acute ischemic stroke. The addition of deep venous drainage to this assessment may provide valuable information to further guide the treatment of these patients.

MATERIALS AND METHODS

We performed a multicenter retrospective cohort study of patients with acute ischemic stroke treated by thrombectomy between January 2013 and January 2021. The internal cerebral veins were scored on a scale of 0-2. This metric was combined with existing cortical vein opacification scores to create a comprehensive venous outflow score from 0 to 8 and stratify patients as having favorable-versus-unfavorable comprehensive venous outflow. Outcome analyses were primarily conducted using the Mann-Whitney U and χ2 tests.

RESULTS

Six hundred seventy-eight patients met the inclusion criteria. Three hundred fifteen were stratified as having favorable comprehensive venous outflow (mean age, 73 years; range, 62-81 years; 170 men), and 363, as having unfavorable comprehensive venous outflow (mean age, 77 years; range, 67-85 years; 154 men). There were significantly higher rates of functional independence (mRS 0-2; 194/296 versus 37/352, 66% versus 11%, P < .001) and excellent reperfusion (TICI 2c/3; 166/313 versus 142/358, 53% versus 40%, P < .001) in patients with favorable comprehensive venous outflow. There was a significant increase in the association of mRS with the comprehensive venous outflow score compared with the cortical vein opacification score (-0.74 versus -0.67, P = .006).

CONCLUSIONS

A favorable comprehensive venous profile is strongly associated with functional independence and excellent postthrombectomy reperfusion. Future studies should focus on patients with venous outflow status that is discrepant with the eventual outcome.

Stroke recurrence is associated with unfavorable intracranial venous outflow in patients with symptomatic intracranial atherosclerotic large vessel severe stenosis or occlusion

Objective

The purpose of this study was to investigate the predictive value of intracranial venous outflow for recurrent cerebral ischemic events (RCIE) in patients with symptomatic intracranial atherosclerotic large-vessel severe stenosis or occlusion (sICAS-S/O).

Methods

This retrospective study included sICAS-S/O patients with anterior circulation who underwent dynamic computed tomography angiography (dCTA) and computed tomography perfusion (CTP). Arterial collaterals were evaluated using the pial arterial filling score for dCTA data, tissue-level collaterals (TLC) were assessed using the high-perfusion intensity ratio (HIR, Tmax >10 s/Tmax >6 s), and cortical veins were evaluated using the multi-phase venous score (MVS) for the vein of Labbé (VOL), sphenoparietal sinus (SPS), and superficial cerebral middle vein (SCMV). The relationships between multi-phase venous outflow (mVO), TLC, and 1-year RCIE were analyzed.

Results

Ninety-nine patients were included, 37 of whom had unfavorable mVO (mVO-) and 62 of whom had favorable mVO (mVO+). Compared with the mVO+ patients, mVO- patients had a higher admission National Institutes of Health Stroke Scale (NIHSS) score (median, 4 [interquartile range (IQR), 0-9] vs. 1 [IQR, 0-4]; p = 0.048), larger ischemic volume (median, 74.3 [IQR, 10.1-177.9] vs. 20.9 [IQR, 5-86.4] mL; p = 0.042), and worse tissue perfusion (median, 0.04 [IQR, 0-0.17] vs. 0 [IQR, 0-0.03]; p = 0.007). Multivariate regression analysis showed that mVO- was an independent predictor of 1-year RCIE.

Conclusion

For patients with sICAS-S/O of the anterior circulation, unfavorable intracranial venous outflow is a potential imaging indicator for predicting higher 1-year RCIE risk.

Collateral Blood Flow and Ischemic Core Growth

Treatment of a large vessel occlusion in the acute ischemic stroke setting focuses on vessel recanalization, and endovascular thrombectomy results in favorable outcomes in appropriate candidates. Expeditious treatment is imperative, but patients often present to institutions that do not have neurointerventional surgeons and need to be transferred to a comprehensive stroke center. These treatment delays are common, and it is important to identify factors that mitigate the progression of the ischemic core in order to maximize the preservation of salvageable brain tissue. Collateral blood flow is the strongest factor known to influence ischemic core growth, which includes the input arterial vessels, tissue-level vessels, and venous outflow. Collateral blood flow at these different levels may be imaged by specific imaging techniques that may also predict ischemic core growth during treatment delays and help identify patients who would benefit from transfer and endovascular therapy, as well as identify those patients in whom transfer may be futile. Here we review collateral blood flow and its relationship to ischemic core growth in stroke patients.

Poor venous outflow profiles increase the risk of reperfusion hemorrhage after endovascular treatment

To investigate whether unfavorable cerebral venous outflow (VO) predicts reperfusion hemorrhage after endovascular treatment (EVT), we conducted a retrospective multicenter cohort study of patients with acute ischemic stroke and large vessel occlusion (AIS-LVO). 629 AIS-LVO patients met inclusion criteria. VO profiles were assessed on admission CT angiography using the Cortical Vein Opacification Score (COVES). Unfavorable VO was defined as COVES ≤ 2. Reperfusion hemorrhages on follow-up imaging were subdivided into no hemorrhage (noRH), hemorrhagic infarction (HI) and parenchymal hematoma (PH). Patients with PH and HI less frequently achieved good clinical outcomes defined as 90-day modified Rankin Scale scores of ≤ 2 (PH: 13.6% vs. HI: 24.6% vs. noRH: 44.1%; p < 0.001). The occurrence of HI and PH on follow-up imaging was more likely in patients with unfavorable compared to patients with favorable VO (HI: 25.1% vs. 17.4%, p = 0.023; PH: 18.3% vs. 8.5%; p = <0.001). In multivariable regression analyses, unfavorable VO increased the likelihood of PH (aOR: 1.84; 95% CI: 1.03-3.37, p = 0.044) and HI (aOR: 2.05; 95% CI: 1.25-3.43, p = 0.005), independent of age, sex, admission National Institutes Health Stroke Scale scores and arterial collateral status. We conclude that unfavorable VO was associated with the occurrence of HI and PH, both related to worse clinical outcomes.

Appearance of medullary and cortical veins on multiphase CT-angiography in patients with acute ischemic stroke

OBJECTIVE

We sought to determine if interhemispheric asymmetry of cortical and medullary veins evaluated on CT angiography can provide a more accurate prediction of outcome in patients with acute ischemic stroke when compared to hemispheric asymmetry of cortical or medullary vein drainage alone.

METHODS

We retrospectively reviewed a database of patients with anterior circulation distribution acute ischemic stroke, who were evaluated by multiphase CTA. Cortical veins were evaluated using the adopted Prognostic Evaluation based on Cortical vein score difference In Stroke (PRECISE) system. Medullary veins were evaluated by the presence of asymmetry determined by 5 or more medullary veins visualized in one hemisphere as compared to the contralateral. Good clinical outcome was defined as a Modified Rankin Scale of 0-2 at 90 days.

RESULTS

64 patients were included. The adopted PRECISE score was associated with a good clinical outcome in patients with AIS (OR=3.29; 95 % CI: 1.16 - 9.30; p = 0.023) and had a stronger association with clinical outcome (AUC=0.644) as compared to the asymmetry of MV (AUC=0.609). In a multivariable logistic regression model, combined medullary and cortical vein asymmetry were independently associated with clinical outcomes (AUC=0.721).

CONCLUSION

Combined cortical and medullary vein interhemispheric asymmetry is a stronger predictor of clinical outcome in acute ischemic stroke compared to cortical or medullary vein asymmetry alone.

Intravenous tPA (Tissue-Type Plasminogen Activator) Correlates With Favorable Venous Outflow Profiles in Acute Ischemic Stroke

BACKGROUND

Intravenous tPA (tissue-type plasminogen activator) is often administered before endovascular thrombectomy (EVT). Recent studies have questioned whether tPA is necessary given the high rates of arterial recanalization achieved by EVT, but whether tPA impacts venous outflow (VO) is unknown. We investigated whether tPA improves VO profiles on baseline computed tomography (CT) angiography (CTA) images before EVT.

METHODS

Retrospective multicenter cohort study of patients with acute ischemic stroke due to large vessel occlusion undergoing EVT triage. Included patients underwent CT, CTA, and CT perfusion before EVT. VO profiles were determined by opacification of the vein of Labbé, sphenoparietal sinus, and superficial middle cerebral vein on CTA as 0, not visible; 1, moderate opacification; and 2, full. Pial arterial collaterals were graded on CTA, and tissue-level collaterals were assessed on CT perfusion using the hypoperfusion intensity ratio. Clinical and demographic data were determined from the electronic medical record. Using multivariable regression analysis, we determined the correlation between tPA administration and favorable VO profiles.

RESULTS

Seven hundred seventeen patients met inclusion criteria. Three hundred sixty-five patients received tPA (tPA+), while 352 patients were not treated with tPA (tPA-). Fewer tPA+ patients had atrial fibrillation (n=128 [35%] versus n=156 [44%]; P=0.012) and anticoagulants/antiplatelet treatment before acute ischemic stroke due to large vessel occlusion onset (n=130 [36%] versus n=178 [52%]; P<0.001) compared with tPA- patients. One hundred eighty-five patients (51%) in the tPA+ and 100 patients (28%) in the tPA- group exhibited favorable VO (P<0.001). Multivariable regression analysis showed that tPA administration was a strong independent predictor of favorable VO profiles (OR, 2.6 [95% CI, 1.7-4.0]; P<0.001) after control for favorable pial arterial CTA collaterals, favorable tissue-level collaterals on CT perfusion, age, presentation National Institutes of Health Stroke Scale, antiplatelet/anticoagulant treatment, history of atrial fibrillation and time from symptom onset to imaging.

CONCLUSIONS

In patients with acute ischemic stroke due to large vessel occlusion undergoing thrombectomy triage, tPA administration was strongly associated with the presence of favorable VO profiles.

The Cerebral Collateral Cascade: Comprehensive Blood Flow in Ischemic Stroke

BACKGROUND AND OBJECTIVES

Robust cerebral collaterals are associated with favorable outcomes in patients with acute ischemic stroke due to large vessel occlusion treated by thrombectomy. However, collateral status assessment mostly relies on single imaging biomarkers and a more comprehensive holistic approach may provide deeper insights into the biology of collateral perfusion on medical imaging. Comprehensive collateralization is defined as blood flow of cerebral arteries through the brain tissue and into draining veins. We hypothesized that a comprehensive analysis of the cerebral collateral cascade (CCC) on an arterial, tissue, and venous level would predict clinical and radiologic outcomes.

METHODS

This was a multicenter retrospective cohort study of patients with acute stroke undergoing thrombectomy triage. CCC was determined by quantifying pial arterial collaterals, tissue-level collaterals, and venous outflow (VO). Pial arterial collaterals were determined by CT angiography; tissue-level collaterals were assessed on CT perfusion. VO was assessed on CT angiography using the cortical vein opacification score. Three groups were defined: CCC+ (good pial collaterals, tissue-level collaterals, and VO), CCC- (poor pial collaterals, tissue-level collaterals, and VO), and CCCmixed (the remainder of the patients). Primary outcome was functional independence (modified Rankin Scale score 0-2) at 90 days. Secondary outcome was final infarct volume.

RESULTS

A total of 647 patients met inclusion criteria: 176 CCC+, 345 CCCmixed, and 126 CCC-. Multivariable ordinal logistic regression showed that CCC+ predicted good functional outcomes (odds ratio [OR] 18.9 [95% CI 8-44.5]; p < 0.001) compared with CCC- and CCCmixed. CCCmixed patients likely had better functional outcomes compared with CCC- patients (OR 2.5 [95% CI 1.2-5.4]; p = 0.014). Quantile regression analysis (50th percentile) showed that CCC+ (β -78.5, 95% CI -96.0 to -61.1; p < 0.001) and CCCmixed (β -64.0, 95% CI -82.4 to -45.6; p < 0.001) profiles were associated with considerably lower final infarct volumes compared with CCC- profiles.

DISCUSSION

Comprehensive assessment of the collateral blood flow cascade in patients with acute stroke is a strong predictor of clinical and radiologic outcomes in patients treated by thrombectomy.

Favourable arterial, tissue-level and venous collaterals correlate with early neurological improvement after successful thrombectomy treatment of acute ischaemic stroke

BACKGROUND AND PURPOSE

Early neurological improvement (ENI) after thrombectomy is associated with better long-term outcomes in patients with acute ischaemic stroke due to large vessel occlusion (AIS-LVO). Whether cerebral collaterals influence the likelihood of ENI is poorly described. We hypothesised that favourable collateral perfusion at the arterial, tissue-level and venous outflow (VO) levels is associated with ENI after thrombectomy.

MATERIALS AND METHODS

Multicentre retrospective study of patients with AIS-LVO treated by thrombectomy. Tissue-level collaterals (TLC) were measured on cerebral perfusion studies by the hypoperfusion intensity ratio. VO and pial arterial collaterals (PAC) were determined by the Cortical Vein Opacification Score and the modified Tan scale on CT angiography, respectively. ENI was defined as improvement of ≥8 points or a National Institutes of Health Stroke Scale score of 0 hour or 1 24 hours after treatment. Multivariable regression analyses were used to determine the association of collateral biomarkers with ENI and good functional outcomes (modified Rankin Scale 0-2).

RESULTS

646 patients met inclusion criteria. Favourable PAC (OR: 1.9, CI 1.2 to 3.1; p=0.01), favourable VO (OR: 3.3, CI 2.1 to 5.1; p<0.001) and successful reperfusion (OR: 3.1, CI 1.7 to 5.8; p<0.001) were associated with ENI, but favourable TLC were not (p=0.431). Good functional outcomes at 90-days were associated with favourable TLC (OR: 2.2, CI 1.4 to 3.6; p=0.001), VO (OR: 5.7, CI 3.5 to 9.3; p<0.001) and ENI (OR: 5.7, CI 3.3 to 9.8; p<0.001), but not PAC status (p=0.647).

CONCLUSION

Favourable PAC and VO were associated with ENI after thrombectomy. Favourable TLC predicted longer term functional recovery after thrombectomy, but the impact of TLC on ENI is strongly dependent on vessel reperfusion.

Venous outflow profiles are associated with early edema progression in ischemic stroke

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.

Cerebral venous outflow profiles are associated with the first pass effect in endovascular thrombectomy

Background

Recent studies found that favorable venous outflow (VO) profiles are associated with higher reperfusion rates after mechanical thrombectomy (MT) in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). Fewer retrieval attempts and first-pass revascularization during MT lead to better functional outcomes.

Objective

To examine the hypothesis that favorable VO profiles assessed on baseline CT angiography (CTA) images correlate with successful vessel reperfusion after the first retrieval attempt and fewer retrieval attempts.

Methods

A multicenter retrospective cohort study of patients with AIS-LVO treated by MT. Baseline CTA was used to determine the cortical vein opacification score (COVES). Favorable VO was defined as COVES ≥3. Primary outcomes were successful with excellent vessel reperfusion status, defined as Thrombolysis in Cerebral Infarction (TICI) 2b/3 and 2c/3 after first retrieval attempt.

Results

617 patients were included in this study, of whom 205 (33.2%) had first pass reperfusion. In univariate analysis, ordinal COVES (p=0.011) values were significantly higher in patients with first pass than in those with non-first pass reperfusion, while the number of patients exhibiting favorable pial arterial collaterals using the Maas scale on CTA did not differ (p=0.243). In multivariable logistic regression analysis, higher COVES were independently associated with TICI 2b/3 (OR=1.25, 95% CI 1.1 to 1.42; p=0.001) and TICI 2c/3 (OR=1.2, 95% CI 1.04 to 1.36; p=0.011) reperfusion after one retrieval attempt, controlling for penumbra volume and time from symptom onset to vessel reperfusion.

Conclusions

Favorable VO, classified as higher COVES, is independently associated with successful and excellent first pass reperfusion in patients with AIS-LVO treated by endovascular thrombectomy.

Distinct intra-arterial clot localization affects tissue-level collaterals and venous outflow profiles

BACKGROUND AND PURPOSE

Arterial clot localization affects collateral flow to ischemic brain in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). We determined the association between vessel occlusion locations, tissue-level collaterals (TLC), and venous outflow (VO) profiles and their impact on good functional outcomes.

METHODS

We conducted a multicenter retrospective cohort study of consecutive AIS-LVO patients who underwent thrombectomy triage. Baseline computed tomographic angiography (CTA) was used to localize vessel occlusion, which was dichotomized into proximal vessel occlusion (PVO; internal carotid artery and proximal first segment of the middle cerebral artery [M1]) and distal vessel occlusion (DVO; distal M1 and M2), and to assess collateral scores. TLC were assessed on computed tomographic perfusion data using the hypoperfusion intensity ratio. VO was determined on baseline CTA by the cortical vein opacification score. Primary outcomes were favorable VO and TLC; secondary outcome was the modified Rankin Scale after 90 days.

RESULTS

A total of 649 patients met inclusion criteria. Of these, 376 patients (58%) had a PVO and 273 patients (42%) had a DVO. Multivariate ordinal logistic regression showed that DVO predicted favorable TLC (odds ratio [OR] = 1.77, 95% confidence interval [CI] = 1.24-2.52, p = 0.002) and favorable VO (OR = 7.2, 95% CI = 5.2-11.9, p < 0.001). DVO (OR = 3.4, 95% CI = 2.1-5.6, p < 0.001), favorable VO (OR = 6.4, 95% CI = 3.8-10.6, p < 0.001), and favorable TLC (OR = 3.2, 95% CI = 2-5.3, p < 0.001), but not CTA collaterals (OR = 1.07, 95% CI = 0.60-1.91, p = 0.813), were predictors of good functional outcome.

CONCLUSIONS

DVO in AIS-LVO patients correlates with favorable TLC and VO profiles, which are associated with good functional outcome.

Rethinking the Collateral Vasculature Assessment in Acute Ischemic Stroke: The Comprehensive Collateral Cascade

ABSTRACT

Occlusion of a cervical or cerebral artery results in disruption of blood flow to the brain and may result in irreversible infarction. Intracranial pial collaterals are a network of arteries that may preserve blood flow to otherwise critically hypoperfused brain areas until vessel recanalization is achieved. The robustness of these arterial collaterals is pivotal for the survivability of ischemic brain tissue and is associated with treatment success and long-term clinical outcome. More recently, the importance of venous outflow from ischemic brain tissue has been appreciated. Arterial collaterals and venous outflow are evaluated by neuroimaging parameters, and recent imaging advances have enabled a more comprehensive assessment of the entire collateral cascade in patients with acute ischemic stroke. Here we review novel imaging biomarkers for the assessment of arterial collaterals, tissue-level collateral blood flow, and venous outflow. We also summarize how a more comprehensive assessment of the cerebral blood flow leads to a better prediction of treatment efficacy and improved clinical outcomes.

Association of Venous Outflow Profiles and Successful Vessel Reperfusion After Thrombectomy

OBJECTIVE

Robust arterial collaterals are associated with successful reperfusion after thrombectomy treatment of acute ischemic stroke due to large vessel occlusion (AIS-LVO). Excellent venous outflow (VO) reflects excellent tissue perfusion and collateral status in patients with AIS-LVO. The goal of this study was to determine whether favorable VO profiles assessed on pretreatment CT angiography (CTA) images correlate with successful vessel reperfusion after thrombectomy in patients with AIS-LVO.

METHODS

This was a multicenter retrospective cohort study of consecutive patients with AIS-LVO treated by thrombectomy. Baseline CTA was used to assess collateral status (Tan scale) and VO using the Cortical Vein Opacification Score (COVES). Favorable VO was defined as COVES ≥3. Primary outcome was excellent vessel reperfusion status (modified Thrombolysis in Cerebral Infarction 2c/3). Secondary outcome was good functional outcome defined as a score of 0 to 2 on the modified Rankin Scale after 90 days.

RESULTS

Five hundred sixty-five patients met the inclusion criteria. Multivariable logistic regression analysis showed that favorable VO (odds ratio [OR] 2.10 [95% confidence interval (CI) 1.39-3.16]; p < 0.001) was associated with excellent vessel reperfusion during thrombectomy, regardless of good CTA collateral status (OR 0.87 [95% CI 0.58-1.34]; p = 0.48). A favorable VO profile (OR 8.9 [95%CI 5.3-14.9]; p < 0.001) and excellent vessel reperfusion status (OR 2.7 [95%CI 1.7-4.4]; p < 0.001) were independently associated with good functional outcome adjusted for age, sex, glucose, tissue plasminogen activator administration, good CTA collateral status, and presentation NIH Stroke Scale score.

CONCLUSION

A favorable VO profile is associated with reperfusion success and good functional outcomes in patients with AIS-LVO treated by endovascular thrombectomy.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that a favorable VO profile is associated with reperfusion success and good functional outcomes in patients with AIS-LVO treated by endovascular thrombectomy.

Absent Cortical Venous Filling Is Associated with Aggravated Brain Edema in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Predicting malignant cerebral edema can help identify patients who may benefit from appropriate evidence-based interventions. We investigated whether absent cortical venous filling is associated with more pronounced early brain edema, which leads to malignant cerebral edema.

MATERIALS AND METHODS

Patients with acute ischemic stroke caused by large-vessel occlusion in the MCA territory who presented between July 2017 and September 2019 to our hospital were included. Collateral filling was rated using the modified Tan scale on CTA, and good collaterals were defined as a score of 2-3. The Cortical Vein Opacification Score (COVES) was calculated, and absent cortical venous filling was defined as a score of 0. Early brain edema was determined using net water uptake on baseline CT images. Malignant cerebral edema was defined as a midline shift of ≥5 mm on follow-up imaging or a massive cerebral swelling leading to decompressive hemicraniectomy or death. Multivariate linear and logistic regression models were performed to analyze data.

RESULTS

A total of 163 patients were included. Net water uptake was significantly higher in patients with absent than in those with favorable cortical venous filling (8.1% versus 4.2%; P < .001). In the multivariable regression analysis, absent cortical venous filling (β = 2.04; 95% CI, 0.75-3.32; P = .002) was significantly and independently associated with higher net water uptake. Absent cortical venous filling (OR, 14.68; 95% CI, 4.03-53.45; P < .001) and higher net water uptake (OR, 1.29; 95% CI, 1.05-1.58; P = .016) were significantly associated with increased likelihood of malignant cerebral edema.

CONCLUSIONS

Patients with absent cortical venous filling were associated with an increased early brain edema and a higher risk of malignant cerebral edema. These patients may be targeted for optimized adjuvant antiedematous treatment.

Venous Outflow Profiles Are Linked to Cerebral Edema Formation at Noncontrast Head CT after Treatment in Acute Ischemic Stroke Regardless of Collateral Vessel Status at CT Angiography

Background Ischemic lesion net water uptake (NWU) at noncontrast head CT enables quantification of cerebral edema in patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO). Purpose To assess whether favorable venous outflow (VO) profiles at CT angiography are associated with reduced NWU and good functional outcomes in patients with AIS due to LVO. Materials and Methods This multicenter retrospective cohort study evaluated consecutive patients with AIS due to LVO who underwent thrombectomy triage between January 2013 and December 2019. Arterial collateral vessel status (Tan scale) and venous output were measured at CT angiography. Venous outflow was graded with use of the cortical vein opacification score, which quantifies opacification of the vein of Labbé, sphenoparietal sinus, and superficial middle cerebral vein. Favorable VO was regarded as a score of 3-6 and unfavorable VO as a score of 0-2. NWU was determined at follow-up noncontrast CT. Multivariable regression analyses were performed to determine the association between favorable VO profiles and NWU after treatment and good functional outcome (modified Rankin Scale, ≤2). Results A total of 580 patients were included. Of the 580 patients, 231 had favorable VO (104 women; median age, 73 years [interquartile range {IQR}, 62-81 years]) and 349 had unfavorable VO (190 women; median age, 77 years [IQR, 66-84 years]). Compared with patients with unfavorable VO, those with favorable VO exhibited lower baseline National Institutes of Health Stroke Scale score (median, 12.5 [IQR, 7-17] vs 17 [IQR, 13-21]), higher Alberta Stroke Program Early CT Score (median, 9 [IQR, 7-10] vs 7 [IQR, 6-8]), and less NWU after treatment (median, 7% [IQR, 4.6%-11.5%] vs 17.9% [IQR, 12.3%-22.2%]). In a multivariable regression analysis, NWU mean difference between patients with unfavorable VO and those with favorable VO was 6.1% (95% CI: 4.9, 7.3; P < .001) regardless of arterial CT angiography collateral vessel status (b coefficient, 0.72 [95% CI: -0.59, 2.03; P = .28]). Favorable VO (odds ratio [OR]: 4.1 [95% CI: 2.2, 7.7]; P < .001) and reduced NWU after treatment (OR: 0.77 [95% CI: 0.73, 0.83]; P < .001) were independently associated with good functional outcomes. Conclusion Favorable venous outflow (VO) correlated with reduced ischemic net water uptake (NWU) after treatment. Reduced NWU and favorable VO were associated with good functional outcomes regardless of CT angiography arterial collateral vessel status. © RSNA, 2021 Online supplemental material is available for this article.

Favorable Venous Outflow Profiles Correlate With Favorable Tissue-Level Collaterals and Clinical Outcome

BACKGROUND AND PURPOSE

Patients with acute ischemic stroke due to large vessel occlusion and favorable tissue-level collaterals (TLCs) likely have robust cortical venous outflow (VO). We hypothesized that favorable VO predicts robust TLC and good clinical outcomes.

METHODS

Multicenter retrospective cohort study of consecutive acute ischemic stroke due to large vessel occlusion patients who underwent thrombectomy triage. Included patients had interpretable prethrombectomy computed tomography, computed tomography angiography, and cerebral perfusion imaging. TLCs were measured on cerebral perfusion studies using the hypoperfusion intensity ratio (volume ratio of brain tissue with [Tmax >10 s/Tmax >6 s]). VO was determined by opacification of the vein of Labbé, sphenoparietal sinus, and superficial middle cerebral vein on computed tomography angiography as 0, not visible; 1, moderate opacification; and 2, full. Clinical and demographic data were determined from the electronic medical record. Using multivariable regression analyses, we determined the association between VO and (1) favorable TLC status (defined as hypoperfusion intensity ratio ≤0.4) and (2) good functional outcome (modified Rankin Scale score, 0-2).

RESULTS

Six hundred forty-nine patients met inclusion criteria. Patients with favorable VO were younger (median age, 72 [interquartile range (IQR), 62-80] versus 77 [IQR, 66-84] years), had a lower baseline National Institutes of Health Stroke Scale (median, 12 [IQR, 7-17] versus 19 [IQR, 13-20]), and had a higher Alberta Stroke Program Early Computed Tomography Score (median, 9 [IQR, 7-10] versus 7 [IQR, 6-9]). Favorable VO strongly predicted favorable TLC (odds ratio, 4.5 [95% CI, 3.1-6.5]; P<0.001) in an adjusted regression analysis. Favorable VO also predicted good clinical outcome (odds ratio, 10 [95% CI, 6.2-16.0]; P<0.001), while controlling for favorable TLC, age, glucose, baseline National Institutes of Health Stroke Scale, and good vessel reperfusion status.

CONCLUSIONS

In this selective retrospective cohort study of acute ischemic stroke due to large vessel occlusion patients undergoing thrombectomy triage, favorable VO profiles correlated with favorable TLC and were associated with good functional outcomes after treatment. Future prospective studies should independently validate our findings.

Single-phase computed tomography angiography sufficiently predicts outcomes after mechanical thrombectomy

BACKGROUND

Arterial collateral (AC) assessed by single-phase computed tomography angiography (CTA) or multiphase CTA has been used to predict clinical outcomes in patients undergoing mechanical thrombectomy (MT). Recently, venous opacification (VO) was proposed as another accurate image marker. This study aimed to compare the efficacy using AC and VO as predictors of MT outcome.

METHODS

Patients with occlusion of the proximal anterior circulation undergoing MT were included retrospectively. We assessed the AC status respectively according to different methods: modified Tan score, Miteff score in single-phase CTA, and pial arterial filling score in multiphase CTA. VO was assessed according to cortical vein opacification score. Favorable clinical outcome was defined as modified Rankin Scale 0-2 90 days after MT. Logistic regression models were established and receiver operating characteristics curve were used to determine the predictability of favorable outcome in patients with adequate AC and VO.

RESULTS

A total of 75 patients were enrolled. Adequate AC identified by modified Tan score (odds ratio, 7.3; p < 0.001), Miteff score (odds ratio, 4.5; p = 0.009), significantly predicted favorable outcome, but not adequate VO. The area under the curve was largest for adequate AC in model of modified Tan score 0.730 (95% CI, 0.60-0.86), while adequate VO showed the least area under the curve: 0.577 (95% CI, 0.43-0.73).

CONCLUSION

We considered adequate AC in single-phase CTA could be reliable enough as an imaging marker rather than adequate VO to predict favorable outcome after MT.