Collateral Score Research Articles

Use of Thick Maximum‐Intensity Projection Brain Computed Tomography Angiography for Evaluation of Baseline Collateral Status Improves Interrater Agreement

Background In acute ischemic stroke caused by large‐vessel occlusion, tissue viability is dependent on the blood supply from leptomeningeal collaterals until reperfusion is achieved. Rapid and accurate evaluation of baseline collateral status is a key marker of eligibility for endovascular therapy but can be challenging to interpret using source images of the computed tomography angiography (SI‐CTA). Our objective was to assess whether the use of thick maximum‐intensity projection computed tomography angiography (MIP‐CTA) improves interrater agreement for evaluation of baseline collaterals status between stroke trainees and an expert stroke neurologist. Methods An expert stroke neurologist and 2 stroke trainees independently reviewed images from 40 brain CTA scans with anterior circulation large‐vessel occlusion and assessed collateral status using the Tan collateral scoring system using SI‐CTA in the first reading and then using MIP‐CTA in the second reading. We calculated interrater agreement and recorded the total time needed in each reading. Results Interrater agreement was fair between the 2 stroke fellows and stroke expert when using SI‐CTA (κ=0.45 with 52.5% agreement). After using MIP‐CTA, interrater agreement improved to moderate (κ=0.69 with 70% agreement). The median reading time was 1.89 minutes per scan using SI‐CTA and 1.00 minute per scan using MIP‐CTA ( P <0.0001). Conclusions We show that using MIP‐CTA, when compared with SI‐CTA, shortens interpretation time and improves interrater agreement between stroke trainees and a stroke imaging expert for the evaluation of baseline collaterals in patients presenting with anterior circulation large‐vessel occlusion.

Unfavorable clinical outcomes in patients with good collateral scores following endovascular treatment for acute ischemic stroke of the anterior circulation: The UNCLOSE study

Background Patients with acute ischemic stroke secondary to large vessel occlusions and good collaterals are frequently associated with favorable outcomes after mechanical thrombectomy, although poor outcomes are observed also in this subgroup. We aimed to investigate the factors associated with unfavorable outcomes (modified Rankin Scale3–6) in this specific subgroup of patients. Methods In total, 219 patients (117 females) with anterior circulation stroke and good collaterals (American Society for Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology grades 3–4), treated by mechanical thrombectomy between 2016 and 2021 at our institution were included in this study. Clinical files and neuroimaging were retrospectively reviewed. Univariate and multivariate analyses were performed to identify the predictors of unfavorable outcomes in the overall population (primary endpoint). Secondary endpoints focused on the analysis of the predictors of unfavorable outcomes in the subgroup of successfully recanalized patients, mortality, and symptomatic intracerebral hemorrhages in the overall population. Results Poor outcome was observed in 47% of the patients despite the presence of good collaterals. Older age ( p < 0.001), higher baseline National Institute of Health stroke scale ( p < 0.001), no intravenous thrombolysis administration ( p = 0.004), > 3 passes ( p = 0.01), and secondary transfers ( p < 0.001) were associated with the primary endpoint. The multivariate analysis showed a predictive effect of modified treatment in cerebral infarction 2b-3 and of first pass effect on symptomatic intracerebral hemorrhage. Conclusions Despite good collaterals, defined through the American Society for Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology scale, poor outcomes occurred in almost half of the patients. Patients with good collaterals not receiving intravenous thrombolysis were significantly associated with unfavorable outcomes, whereas first pass effect was not significantly correlated with clinical outcome in this specific cohort of patients. Different methods to assess collaterals should also be investigated.

Basilar artery bifurcation anatomy as a determinant of recanalization and stroke outcome: Basilar artery bifurcation anatomy and stroke outcome

ObjectivesThrombectomy improves outcomes in patients with basilar artery (BA) occlusion. We hypothesized that the anatomic configuration of the BA bifurcation, classified as T- or Y-shaped, may impact the outcome as a T-shaped BA would involve more deep penetrating arteries of the midbrain and thalamus. Materials and methodsIn this 2-center retrospective cohort study, we included patients with stroke due to distal BA occlusion and performed blinded classification of their BA distal bifurcation as either T- or Y-shaped. The primary outcomes were favorable outcome at 90-days (modified Rankin Scale 0 – 2) and successful recanalization (TICI scores 2B or 3). Results70 patients (mean age 66 years, 36% women) were included. 38 had T- and 32 had Y-shaped bifurcations. Baseline characteristics were similar for both groups, including demographics, onset to arterial puncture time, baseline NIHSS, THRIVE score, posterior circulation collateral score, and presence of tandem occlusion. Comparing the T- to the Y- shape, there was no difference in the likelihood of successful recanalization (RR: 1.02, CI: [0.86–1.21], p=1.00) nor 90-day favorable mRS (0-2) score (RR: 0.58, CI: [0.25–1.32]; p=0.18). Similarly, mortality at 30 and 90-days were not significantly affected by the type of bifurcation. ConclusionsThe configuration of the basilar artery does not significantly impact on recanalization success or stroke outcome in our study. Further studies are needed to confirm our observations.

Abstract 247: Visual versus Computer Software Assessment of Perfusion in Anterior Circulation Stroke Treated with Mechanical Thrombectomy

Introduction In the absence of an automated software analysis, the role of computed tomography perfusion (CTP) in a real time clinical practice is not well established. In a pilot study on 318 acute ischemic stroke (AIS) patients treated with mechanical thrombectomy (MT), we established that visual, semi quantitative evaluation of CTP strongly correlates with clinical outcome, independently of collateral circulation status and ASPECT score. The visual CTP assessment was based only on TTP (time to peak) perfusion maps that are widely accessible, simple to perform on any CT scanner and easy to analyze even by a non‐specialized radiologist. To expand on these results, we are currently performing a direct comparison of the visual and computer‐based CTP assessment and their independent prediction of clinical outcome in AIS patients treated with MT in anterior circulation. Methods The single center consecutive CT investigations of AIS patients treated with MT in the anterior circulation were evaluated retrospectively. ASPECT score and collateral circulation evaluation based on the Maas score were determined. CTP assessments, performed either by the visual or computer based method, were graded into four categories, from least to most favorable. Visual grading was based on the percentage of »black regions« on TTP parametric maps, which represent a complete fallout of signal and presumably correlate with infarction core, in comparison to the whole area of the hypo‐perfused territory. Computer based CTP assessment was performed by syngo® Neuro Perfusion CT software. Ischemic core was defined as an area with reduced relative cerebral blood flow (rCBF) below 30% and the hypo‐perfused territory as an area with time to maximum (Tmax) residue function exceeding 6 seconds. The relative volumes of the core were transformed into percentages and graded accordingly. The primary endpoint was excellent functional outcome defined as modified Rankin Scale (mRS) ≤2 at 90 days after MT. Results In the pilot study, we included 318 patients, with 142 (45%) having mRS≤ 2 after 90 days, and the mortality rate was 24%. The visually determined CTP grade demonstrated statistically significant independent correlation with the clinical outcome, irrespective of the collateral circulation, ASPECT score and age (OR 2.5; p= 0.011). As an extension of the pilot study, we are undergoing analysis of 1029 patients that underwent MT from 2013 until the end of 2022. The preliminary findings point towards a good correlation between the visual and computer based CTP assessment. Conclusion The preliminary results of the ongoing direct comparison of the visual and computer based CTP assessment point towards a good correlation with concordant predictability of clinical outcome of both methods. The results of this study provide an additional scientific background for using the visual semi‐quantitative CTP evaluation in clinical practice for patients who are candidates for MT. As this method is simple and easy to use, it can be performed in almost any CT unit, even without a software program for CTP analysis or advanced subspecialized knowledge in neuroradiology.

Abstract 256: Proposal of multimodal CT‐based scoring system in prediction of hemorrhagic transformation in acute ischemic stroke

Introduction The routinely used computed tomography (CT)‐based workup in the setting of acute ischemic stroke (AIS) includes non‐contrast brain CT, CT angiography (CTA), and CT perfusion. Several CT, CTA, CTP‐based radiological biomarkers of hemorrhagic transformation (HT) were reported. To assess the predictive value of the combined multimodal CT parameters for HT after AIS and proposal of predictive scoring scale. Methods The source images of the NCCT, CTA and CTP of 282 AIS patients involving the anterior circulation (HT = 91, non‐HT = 191) were retrospectively reviewed and the following biomarkers were recorded and analyzed: Early subtle ischemic signs, hyperdense middle cerebral artery sign (HMCAS) and Alberta Stroke Program Early CT Score (ASPECTS) < 7 in NCCT, large‐vessel occlusion (LVO), clot burden score (CBS) < 6, large‐vessel occlusion, poor collateral score (CS) and Tmax > 6 s ≥ 56.5 ml. A scoring system to predict HT based on these biomarkers was developed. Each biomarker counts for a single point with the total score ranging from 0 to 7. Results All the aforementioned multimodal CT biomarkers and the selected cut offs were significantly associated with higher HT risk. The calculated scores were statistically significant different between the HT and the non‐HT groups with AUC 0.761 (95% CI 0.703–0.819, P < 0.0000001). Rates of HT were approximately five times higher in patients with score ≥ 3. Conclusion Multimodal CT‐based scoring system may provide highly reliable predictive model of hemorrhagic transformation in acute ischemic stroke.

Abstract 227: Combined Technique Versus Stent‐Retriever Alone: Angioarchitectural and Technical Analysis

Introduction Combined technique mechanical thrombectomy with contact aspiration with stent‐retriever has been shown to lead to comparable final reperfusion rates compared with stent retriever alone. We aimed to explore if anatomical and technical features could have interaction with the chances of reperfusion by each technique. Methods Retrospective analysis of a prospective mechanical thrombectomy (MT) database. Inclusion criteria: anterior circulation large vessel occlusion(LVO) due to carotid terminus or proximal MCA(M1) occlusion, first‐line stent‐retriever (SR) alone or combined technique (SR plus aspiration), and angiographic run with stent in place. The primary analysis was the interaction between clinical and angiographic characteristics and first‐line MT modality on first‐pass effect (FPE; first‐pass eTICI2c‐3). Secondary analyses aimed to evaluate predictors of FPE. Results A total of 150 patients were included in the analysis (SR alone,n=62 vs. combined technique, n=88). Demographics, vascular risk factors and NIHSS were comparable between groups. The SR group had higher IV‐tPA use (41.9%vs.26.1%,P=0.04), higher rates of FPE(64.5%vs.47.7%,P=0.04) but similar baseline ASPECTS, CTA collateral score, clot burden, as compared to the combined technique. Anatomical and technical variables (reperfusion channel, SR position in dominant MCA division, angle of interaction, diameter of stent proximal to clot, diameter of stent distal to clot, type of extracranial carotid or cavernous carotid tortuosity, clot length were comparable between both groups. None of the anatomical and technical factors were found to have an interaction with the modality (SR alone vs combined technique) on the chances of FPE (Pinteraction >0.05)(Figure). FPE was observed in 54.6% of the entire cohort. Multivariable analysis showed that use of IV‐tPA(OR 156.5,95%CI 4.59‐5334.8,P=0.005), lower angle of interaction (OR 0.94,95%CI 0.89‐0.99,P=0.03), presence of reperfusion channel (OR 145.8,95%CI 1.96‐108277.4),P=0.02), higher clot burden score (OR 8.17,95%CI 1.38 ‐48.21,P=0.02), type‐3 cavernous ICA tortuosity (OR 0.001,95%CI 0‐0.23,P=0.01) were independently associated FPE. Conclusion We could not identify any anatomical or technical features that predisposed to a benefit in adding catheter aspiration to SR thrombectomy. IV r‐TPA, clot burden score, presence of reperfusion channel, type of cavernous carotid tortuosity, and angle of interaction were found independently associated with FPE. Large sample studies are warranted.

Abstract 068: Basilar artery bifurcation anatomy as a determinant of recanalization and stroke outcome

Introduction Background: Thrombectomy improves outcomes in patients with basilar artery (BA) occlusion [1,2]. We hypothesized that the anatomic configuration of the BA bifurcation, classified as T‐ or Y‐shaped, may impact the outcome. Specifically, we expected that a T‐shaped BA would involve more deep penetrating arteries of the midbrain and thalamus, leading to greater disability or death [3,4]. Methods In this 2‐center retrospective cohort study over seven years, we included patients with stroke due to distal BA occlusion and performed blinded classification of their BA anatomy as either T‐ or Y‐shaped [Figure 1]. The primary outcomes were favorable functional status at 90 days (modified Rankin Scale 0 – 2) and successful reperfusion (TICI scores 2B or 3). Results 70 patients (mean age 66 years, 36% women) were included. 38 had T‐ and 32 had Y‐shaped bifurcations. Baseline characteristics were similar for both groups, including demographics, treatment time, baseline NIHSS, THRIVE score, posterior circulation collateral score, and presence of tandem occlusion. Comparing the T‐ to the Y‐ shape, there was no difference in the likelihood of successful reperfusion (1.09 [0.52–2.27], p=1.00) nor 90‐day favorable mRS (0‐2) score (RR: 0.68 [0.37–1.27]; p=0.18). Similarly, mortality at 30 and 90 days were not significantly affected by the type of bifurcation. Conclusion The configuration of the basilar artery does not significantly impact reperfusion success or stroke outcome.

Prognostic value of the baseline magnetic resonance score in patients with acute posterior circulation ischaemic stroke after mechanical thrombectomy

To investigate the prognostic value of the composite posterior circulation Acute Stroke Prognosis Early Computed tomography (CT) Score (ASPECTS)-Collaterals (pcASCO) score, which combines diffusion-weighted imaging (DWI) posterior circulation ASPECTS (pcASPECTS) and the magnetic resonance angiography (MRA)-collateral circulation score at baseline among patients with acute posterior circulation ischaemic stroke after mechanical thrombectomy. Patients with acute posterior circulation ischaemic stroke who underwent mechanical thrombectomy were analysed retrospectively. The DWI-pcASPECTS and MRA-collateral circulation score before treatment and the modified Rankin Scale (mRS) at 90 days after treatment were used as the endpoints. An mRS ≤2 was defined as a good prognosis, and an mRS ≥3 was defined as a poor prognosis. Multivariate logistic regression was used to analyse independent predictors of functional outcome 90 days after mechanical thrombectomy. Mechanical thrombectomy was performed in 57 patients; 38 patients had a good prognosis, 19 patients had a poor prognosis, and 33 patients were successfully recanalised. Univariate logistic regression found that National Institute of Health Stroke Scale (NIHSS) score (OR: 1.18, p<0.001), pcASPECTS (OR: 1.91, p=0.028) and pcASCO score (OR: 0.51, p=0.001) were factors of good functional outcome. Receiver operating characteristic curve (ROC curve) analysis showed that the diagnostic efficiency of the NIHSS and pcASCO was better (AUC=0.88, 0.83, p<0.05) than that of the pcASPECTS (AUC=0.65). The prediction model was established by age, NIHSS, and pcASCO, and the diagnostic efficiency of the prediction model was better (AUC=0.94). The composite MR-pcASCO score can be used as an important predictor of the prognosis of patients with acute posterior circulation ischaemic stroke after mechanical thrombectomy.

Correlation between Regional Leptomeningeal Collateral Score by MR Angiography and Clinical Outcome in Patients with Acute Ischemic Stroke

Correlation between Regional Leptomeningeal Collateral Score by MR Angiography and Clinical Outcome in Patients with Acute Ischemic Stroke

Imaging features of cardioembolic stroke on 4-dimensional computed tomography angiography.

Identifying cardioembolic stroke is important for the decision-making of endovascular treatment and anticoagulation therapy. We aimed to explore the features of cardioembolic stroke on 4-dimensional (4D) computed tomography angiography (4D-CTA) and assess whether these features can assist in classifying stroke etiology. In this retrospective study, we analyzed the images of 294 patients with acute ischemic stroke (AIS) from July 2020 to February 2022 at the First Affiliated Hospital of Chongqing Medical University, which had been consecutively collected. The data of 110 patients with occlusion of the M1/M2 segment of the middle cerebral artery (MCA) with/without intracranial internal carotid artery (ICA) occlusion were analyzed to calculate the clot burden score (CBS) and collateral score (CS), and the data of 88 patients with a clear origin and distal part were analyzed to measure clot length. Maximum intensity projection (MIP) and time MIP (tMIP) post-processing were used to assess the clot features. The Mann-Whitney U test was used to compare the clot characteristics between the 2 groups. Binary logistic regression was performed to assess the association between the image characteristics and cardioembolic stroke. Moreover, the receiver operating characteristic (ROC) curve was used to test the diagnostic efficacy of MIP/tMIP clot features in classifying cardioembolic stroke. Age, high-risk factors for cerebrovascular disease, high/medium-risk sources of cardioembolic stroke, clot length, CBS, and CS were significantly different between the cardioembolic stroke group and non-cardioembolic stroke group (P<0.05). In the cardioembolic stroke group, the median MIP and tMIP clot length was 12 mm [interquartile range (IQR), 8.3-17.4 mm] and 9.3 mm (IQR, 6.8-14.3 mm), respectively. In the non-cardioembolic stroke group, the median MIP and tMIP clot length was 6.5 mm (IQR, 4.7-11.5 mm) and 5.8 mm (IQR, 3.9-10.6 mm), respectively. Binary logistic regression showed that cardioembolic stroke was significantly associated with MIP-clot length [odds ratio (OR), 1.15; 95% confidence interval (CI): 1.02-1.29; P<0.05], tMIP-clot length (OR, 1.18; 95% CI: 1.02-1.36; P<0.05), and tMIP-CBS (OR, 3.96; 95% CI: 1.08-14.58; P<0.05). The area under the ROC curve (AUC) values of MIP clot length for identifying cardioembolic stroke were 0.75 (95% CI: 0.65-0.84, P<0.05), with a cut-off value of >7.4 mm [sensitivity: 84.62% (95% CI: 69.50-94.10%); specificity: 59.18% (95% CI: 44.20-73.00%)]. The AUC value of tMIP clot length was 0.72 (95% CI: 0.61-0.81, P<0.05), with a cut-off value of >5.4 mm [sensitivity: 92.31% (95% CI: 79.10-98.40%); specificity: 48.98% (95% CI: 34.40-63.70%)]. Clot length and CBS were overestimated on MIP images. Among the clot characteristics, clot length could identify cardioembolic stroke.

Resolving the Smoking Paradox: No Evidence for Smoking-Induced Preconditioning in Large Vessel Occlusion Stroke

Introduction: Smoking is an established risk factor for stroke. However, several studies have reported a better outcome after stroke for patients who smoke. According to this “smoking paradox” hypothesis, smoking might promote less severe strokes, higher collateral scores, and smaller infarct cores. Methods: In this retrospective study, we screened data of 2,980 acute ischemic stroke patients with MCA-M1 occlusion treated with mechanical thrombectomy. Patients were categorized according to smoking status (current, former, or never). We assessed univariate associations between clinical characteristics and smoking status. Subsequently, we used adjusted regression analysis to evaluate associations of smoking with stroke severity on admission (National Institutes of Health Stroke Scale [NIHSS]; primary endpoint), infarct core volume, and collateral status (secondary endpoints). Results: Out of 320 patients, 19.7% (n = 63) were current smokers and 18.8% (n = 60) were former smokers. Admission NIHSS, reperfusion success, and modified Rankin Scale (mRS) after 3–6 months were similar in all groups. Current smokers were younger, more often male and less likely to have atrial fibrillation compared to former and never smokers. In regression analyses, smoking status was neither associated with admission NIHSS (estimate 0.54, 95% confidence interval [CI]: −1.27–2.35, p = 0.557) nor with collateral status (estimate 0.79, 95% CI: 0.44–1.44, p = 0.447) or infarct core volume (estimate −0.69, 95% CI: −15.15–13.77, p = 0.925 for current vs. never smokers). Conclusion: We could not confirm the smoking paradox. Our results support the fact that smoking causes stroke at a younger age, highlighting the role of smoking as a modifiable vascular risk factor.

Effect of arteriosclerotic intracranial arterial vessel wall enhancement on downstream collateral flow.

The effect of arteriosclerotic intracranial arterial vessel wall enhancement (IAVWE) on downstream collateral flow found in vessel wall imaging (VWI) is not clear. Regardless of the mechanism underlying IAVWE on VWI, damage to the patient's nervous system caused by IAVWE is likely achieved by affecting downstream cerebral blood flow. The present study aimed to investigate the effect of arteriosclerotic IAVWE on downstream collateral flow. The present study recruited 63 consecutive patients at the Second Hospital of Hebei Medical University from January 2021 to November 2021 with underlying atherosclerotic diseases and unilateral middle cerebral artery (MCA) M1-segment stenosis who underwent an magnetic resonance scan within 3 days of symptom onset. The patients were divided into 4 groups according to IAVWE and the stenosis ratio (Group 1, n = 17; Group 2, n = 19; Group 3, n = 13; Group 4, n = 14), and downstream collateral flow was analyzed using three-dimensional pseudocontinuous arterial spin labeling (3D-pCASL) and RAPID software. The National Institutes of Health Stroke Scale (NIHSS) scores of the patients were also recorded. Two-factor multivariate analysis of variance using Pillai's trace was used as the main statistical method. No statistically significant difference was found in baseline demographic characteristics among the groups. IAVWE, but not the stenosis ratio, had a statistically significant significance on the late-arriving retrograde flow proportion (LARFP), hypoperfusion intensity ratio (HIR), and NIHSS scores ( F = 20.941, P <0.001, Pillai's trace statistic = 0.567). The between-subject effects test showed that IAVWE had a significant effect on the three dependent variables: LARFP ( R2 = 0.088, F = 10.899, P = 0.002), HIR ( R2 = 0.234, F = 29.354, P <0.001), and NIHSS ( R2 = 114.339, F = 33.338, P <0.001). Arteriosclerotic IAVWE significantly reduced downstream collateral flow and affected relevant neurological deficits. It was an independent factor affecting downstream collateral flow and NIHSS scores, which should be a focus of future studies. ChiCTR.org.cn, ChiCTR2100053661.

Evaluation of the lower extremity blood supply in no-option critical limb ischemia patients with stem cell transplantation by time maximum intensity projection CT perfusion: A single-centre prospective study.

Cell therapy has had satisfactory safety and efficacy outcomes for no-option critical limb ischaemia (NO-CLI) patients. In the current study, we aimed to compare the image quality of ischaemic lower limb blood vessels shown on volumetric CT-based time maximum intensity projection CT perfusion (t-MIP CTP) versus single-phase CTA (sCTA). We also tried to quantify the blood flow of the ischaemic lower extremity based on the t-MIP technique, not only to precisely show the dynamic change in blood flow from before to after cell therapy but also to detect any relationship between this change and patient prognosis. A total of 31 patients with thromboangiitis obliterans (TAO)-induced NO-CLI who had been referred from the department of vascular surgery to undergo autologous stem cell transplantation into a single limb from January 2020 to March 2021 were prospectively enrolled in this study. Preoperative sCTA or t-MIP CTP and postoperative 1-month t-MIP CTP were performed in all patients. Clinical outcomes, including the 1-month ankle-brachial index (ABI) and 3-month CLI status, were also analysed. Image quality, including objective scores (attenuation, signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]), subjective scores and collateral scores, was compared between preoperative sCTA and t-MIP CTP. Vascular volume was calculated as the total volume (mL) of lower limb arteries within the scanning range. All images and calculations were performed by 2 separate radiologists. Receiver operating characteristic curves were drawn to reveal the sensitivity and specificity of vascular volume and ABI in predicting prognosis. Both sCTA and t-MIP CTP images exhibited good quality for diagnosis. t-MIP CTP images showed significantly higher attenuation, SNR and CNR in all arterial segments (popliteal artery, anterior tibial artery, posterior tibial artery and peroneal artery). In subjective and collateral score evaluations, t-MIP CTP images were also significantly better than sCTA images (both p < .05). At 1 month after transplantation, both vascular volume and ABI showed significant improvement (both p < .01). At 3months after transplantation, 38.71% of patients (12/31) achieved CLI relief (Rutherford class < 4). Through the receiver operating characteristic (ROC) curve, the 1-month vascular volume increase ratio showed better ability to predict the 3-month prognosis (radiologist 1: AUC, 0.757; sensitivity, 0.750; specificity, 0.840; radiologist 2: AUC, 0.803; sensitivity, 0.500; specificity, 1.000) than the 1-month ABI increase ratio (AUC, 0.607; sensitivity, 0.230; specificity, 0.820) or 1-month ABI (AUC, 0.410; sensitivity, 0.080; specificity, 0.580). t-MIP CTP showed significantly higher-quality images of ischaemic limb vascularity than sCTA. t-MIP CTP can reveal the anatomical information of collaterals more accurately, which is of great importance for NO-CLI patients undergoing cell transplantation. The 1-month vascular volume increase ratio can predict the 3-month prognosis more precisely on this basis.

Development and Validation of a Postprocedural Model to Predict Outcome After Endovascular Treatment for Ischemic Stroke

Outcome prediction after endovascular treatment (EVT) for ischemic stroke is important to patients, family members, and physicians. To develop and validate a model based on preprocedural and postprocedural characteristics to predict functional outcome for individual patients after EVT. A prediction model was developed using individual patient data from 7 randomized clinical trials, performed between December 2010 and December 2014. The model was developed within the Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials (HERMES) collaboration and external validation in data from the Dutch Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN) Registry of patients treated in clinical practice between March 2014 and November 2017. Participants included patients from multiple centers throughout different countries in Europe, North America, East Asia, and Oceania (derivation cohort), and multiple centers in the Netherlands (validation cohort). Included were adult patients with a history of ischemic stroke from an intracranial large vessel occlusion in the anterior circulation who underwent EVT within 12 hours of symptom onset or last seen well. Data were last analyzed in July 2022. A total of 19 variables were assessed by multivariable ordinal regression to predict functional outcome (modified Rankin Scale [mRS] score) 90 days after EVT. Variables were routinely available 1 day after EVT. Akaike information criterion (AIC) was used to optimize model fit vs model complexity. Probabilities for functional independence (mRS 0-2) and survival (mRS 0-5) were derived from the ordinal model. Model performance was expressed with discrimination (C statistic) and calibration. A total of 781 patients (median [IQR] age, 67 [57-76] years; 414 men [53%]) constituted the derivation cohort, and 3260 patients (median [IQR] age, 72 [61-80] years; 1684 men [52%]) composed the validation cohort. Nine variables were included in the model: age, baseline National Institutes of Health Stroke Scale (NIHSS) score, prestroke mRS score, history of diabetes, occlusion location, collateral score, reperfusion grade, NIHSS score at 24 hours, and symptomatic intracranial hemorrhage 24 hours after EVT. External validation in the MR CLEAN Registry showed excellent discriminative ability for functional independence (C statistic, 0.91; 95% CI, 0.90-0.92) and survival (0.89; 95% CI, 0.88-0.90). The proportion of functional independence in the MR CLEAN Registry was systematically higher than predicted by the model (41% vs 34%), whereas observed and predicted survival were similar (72% vs 75%). The model was updated and implemented for clinical use. The prognostic tool MR PREDICTS@24H can be applied 1 day after EVT to accurately predict functional outcome for individual patients at 90 days and to provide reliable outcome expectations and personalize follow-up and rehabilitation plans. It will need further validation and updating for contemporary patients.

The Predictive Value of Cerebral Veins on Hemorrhagic Transformation After Endovascular Treatment in Acute Ischemic Stroke Patients: Enhanced Insights From Venous Collateral Circulation Analysis Using Four-Dimensional CTA

A significant complication of endovascular treatment (EVT) is hemorrhagic transformation (HT), which can worsen the outcomes of patients with acute ischemic stroke (AIS). This study aimed to evaluate the predictive value of venous collateral circulation on HT in patients with AIS undergoing EVT. We retrospectively analyzed 126 patients with AIS who received EVT. The four-dimensional computed tomography angiography-based venous collateral score (4D-VCS) and arterial collateral circulation score (4D-ACS) were used to assess venous and arterial collaterals, respectively. Significant variables were identified using the least absolute shrinkage and selection operator algorithm. Logistic regression analysis, receiver operating characteristic (ROC) analysis, and DeLong's test were conducted. HT occurred in 41.3% (52/126) of patients. Higher clot burden score (CBS; odds ratio [OR]: 0.82, 95% confidence interval [CI]: 0.71-0.95, p=0.009), better arterial collateral circulation (OR: 0.59, 95% CI: 0.42-0.83, p=0.003), and better venous collateral circulation (OR: 0.85, 95% CI: 0.73-0.97, p=0.020) were significantly associated with reduced HT risk. The area under the curve (AUC) values for CBS, 4D-ACS, and 4D-VCS were 0.730, 0.772, and 0.795, respectively. Model 1 (4D-VCS+CBS) achieved AUC of 0.820, significantly improving over CBS alone (p=0.0133). Model 2 (4D-VCS+4D-ACS) had an AUC of 0.829, significantly higher than 4D-ACS alone (p=0.0271). Model 3 (4D-ACS+CBS) had an AUC of 0.790. Model 4 (4D-VCS+4D-ACS+CBS) showed highest AUC of 0.851. Significant correlations were found between 4D-VCS and ischemic core volume (r=-0.684, p<0.001) and between 4D-VCS and mismatch ratio (r=0.558, p<0.001). Evaluating venous collateral circulation using 4D-VCS could improve HT risk prediction in patients with AIS after EVT. When combined with other predictors, 4D-VCS may potentially enhance diagnostic performance, which suggests the potential role of venous collateral circulation in predicting HT risk.

Parenchymal Blood Volume Changes Immediately After Endovascular Thrombectomy Predict Futile Recanalization in Patients with Emergent Large Vessel Occlusion

More than one third of acute ischemic stroke (AIS) patients do not recover to functional independence even if endovascular thrombectomy (EVT) is performed rapidly and successfully. This suggests that angiographic recanalization does not necessarily lead to tissue reperfusion. Although recognition of reperfusion status after EVT is pivotal for optimal postoperative management, reperfusion imaging assessment immediately after recanalization has not been fully investigated. The present study aimed to evaluate whether reperfusion status based on parenchymal blood volume (PBV) assessment after angiographic recanalization influences infarct growth and functional outcome in patients who have undergone EVT following AIS. Seventy-nine patients who underwent successful EVT for AIS were retrospectively analyzed. PBV maps were acquired from flat-panel detector computed tomography (CT) perfusion images before and after angiographic recanalization. Reperfusion status was assessed from PBV values and their changes in regions of interest and collateral score. Post-EVT PBV ratio and ΔPBV ratio, as PBV parameters indicating the degree of reperfusion, were significantly lower in the unfavorable prognosis group (P < 0.01 each). Poor reperfusion on PBV mapping was associated with significantly longer puncture-to-recanalization time, lower collateral score, and higher frequency of infarct growth. Logistic regression analysis identified low collateral score and low ΔPBV ratio as associated with poor prognosis after EVT (odds ratios, 2.48, 3.72; 95% confidence intervals, 1.06-5.81, 1.20-11.53; P=0.04, 0.02, respectively). Poor reperfusion in severely hypoperfused territories on PBV mapping immediately after recanalization may predict infarct growth and unfavorable prognosis in patients who undergo EVT following AIS.

Imaging predictors of clinical outcomes after endovascular treatment in MRI-selected patients with acute basilar artery occlusion

PurposeWe aimed to investigate the impact of baseline infarct area and collateral status (CS), which are imaging predictors of clinical outcome following stroke, after endovascular treatment (EVT) in MRI-selected patients with acute basilar artery occlusion (BAO). MethodsPatients with acute BAO who underwent EVT within 24 h after stroke from December 2013 to February 2021 were included in this retrospective, multicenter, observational study. The baseline infarct area was evaluated by the posterior circulation of Acute Stroke Prognosis Early Computed Tomography Score (pc-ASPECTS) using diffuse-weighted imaging (DWI), and CS was assessed by measuring the computed tomography angiography of the basilar artery (BATMAN) score and the posterior circulation collateral score (PC-CS) using magnetic resonance angiography (MRA). A Good outcome was defined as a modified Rankin scale score ≤ 3 at 3 months. For each imaging predictor, a multivariate logistic regression analysis was performed to evaluate its impact on good outcomes. ResultsA total of 86 patients were analyzed, and 37 (43.0%) had a good outcome. The latter showed significantly higher pc-ASPECTS than those without good outcomes. In multivariate analyses, a pc-ASPECTS ≥ 7 was significantly associated with good outcomes (OR, 2.98 [95% CI, 1.10–8.13], P = 0.032), while PC-CS ≥ 4 (OR, 2.49 [95% CI, 0.92–6.74], P = 0.073) and BATMAN score ≥ 5 (OR, 1.51 [95% CI, 0.58–3.98], P = 0.401) were not. ConclusionsIn MRI-selected patients with acute BAO, pc-ASPECTS on DWI was an independent predictor of clinical outcomes after EVT, while the MRA-based CS assessments were not.

The predictors of prognosis in endovascular treatment of basilar artery occlusion

Background &amp; Objective: Data about outcomes of endovascular treatment (EVT) in basilar artery occlusion (BAO) are limited. The aim of this study is to evaluate the predictors of functional outcome and to investigate the benefit of bridging intravenous thrombolysis (IVT) and the impact of first-pass effect (FPE) on prognosis. Methods: A total of 57 consecutive BAO patients who received EVT at our tertiary stroke center between January 2018 and March 2021 were retrospectively analyzed. The primary outcome was to evaluate excellent prognosis (mRS 0-1) and mortality (mRS 6) at day 90. The secondary outcome was to define the benefit of bridging IVT and the impact of FPE on prognosis. The safety outcome was symptomatic intracranial hemorrhage (sICH). National Institutes of Health Stroke Scale (NIHSS) at admission and at 24 hours, collateral scores, successful recanalization, asymptomatic ICH, embolization, malignant infarction and decompression were also evaluated. Results: The mean age of the patients was 64.1 ± 14.5 years. Male-to-female ratio was 1.7. Hypertension (HT) was the most common risk factor. Bridging IVT was performed in nine patients (15.8%). The FPE rate was 56.1%. NIHSS scores at admission and at 24 hours were found to be statistically significant predictors of prognosis (P=0.023 and P&lt;0.001, respectively). Bridging IVT, FPE, successful recanalization and collateral status did not significantly predict outcome. Conclusion: Lower NIHSS scores at admission and at 24 hours were significantly associated with excellent prognosis. NIHSS scores at admission and at 24 hours were significantly higher in mortality group. sICH did not predict mortality.

Automated LVO detection and collateral scoring on CTA using a 3D self-configuring object detection network: a multi-center study

The use of deep learning (DL) techniques for automated diagnosis of large vessel occlusion (LVO) and collateral scoring on computed tomography angiography (CTA) is gaining attention. In this study, a state-of-the-art self-configuring object detection network called nnDetection was used to detect LVO and assess collateralization on CTA scans using a multi-task 3D object detection approach. The model was trained on single-phase CTA scans of 2425 patients at five centers, and its performance was evaluated on an external test set of 345 patients from another center. Ground-truth labels for the presence of LVO and collateral scores were provided by three radiologists. The nnDetection model achieved a diagnostic accuracy of 98.26% (95% CI 96.25–99.36%) in identifying LVO, correctly classifying 339 out of 345 CTA scans in the external test set. The DL-based collateral scores had a kappa of 0.80, indicating good agreement with the consensus of the radiologists. These results demonstrate that the self-configuring 3D nnDetection model can accurately detect LVO on single-phase CTA scans and provide semi-quantitative collateral scores, offering a comprehensive approach for automated stroke diagnostics in patients with LVO.

Optimization of collateral grading on computer tomography angiography.

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