Cerebral Blood Volume Alberta Stroke Program Early CT Score Research Articles

Automated Perfusion Calculations vs. Visual Scoring of Collaterals and CBV-ASPECTS

PurposeUse of automated perfusion software has gained importance for imaging of stroke patients for mechanical thrombectomy (MT). We aim to compare four perfusion software packages: 1) with respect to their association with 3‑month functional outcome after successful reperfusion with MT in comparison to visual Cerebral Blood Volume - Alberta Stroke Program Early CT Score (CBV-ASPECTS) and collateral scoring and 2) with respect to their agreement in estimation of core and penumbra volume.MethodsThis retrospective, multicenter cohort study (2015–2019) analyzed data from 8 centers. We included patients who were functionally independent before and underwent successful MT of the middle cerebral artery. Primary outcome measurements were the relationship of core and penumbra volume calculated by each software, qualitative assessment of collaterals and CBV-APECTS with 3‑month functional outcome and disability (modified Rankin scale >2). Quantitative differences between perfusion software measurements were also assessed.ResultsA total of 215 patients (57% women, median age 77 years) from 8 centers fulfilled the inclusion criteria. Multivariable analyses showed a significant association of RAPID core (common odds ratio, cOR 1.02; p = 0.015), CBV-ASPECTS (cOR 0.78; p = 0.007) and collaterals (cOR 0.78; p = 0.001) with 3‑month functional outcome (shift analysis), while RAPID core (OR 1.02; p = 0.018), CBV-ASPECTS (OR 0.77; p = 0.024), collaterals (OR 0.78; p = 0.007) and OLEA core (OR 1.02; p = 0.029) were significantly associated with 3‑month functional disability. Mean differences on core estimates between VEOcore and RAPID were 13.4 ml, between syngo.via and RAPID 30.0 ml and between OLEA and RAPID −3.2 ml.ConclusionCollateral scoring, CBV-ASPECTS and RAPID were independently associated with functional outcome at 90 days. Core and Penumbra estimates using automated software packages varied significantly and should therefore be used with caution.

The problem of strict image-based inclusion criteria for mechanical thrombectomy - an analysis of stroke patients with an initial low CBV-ASPECTS score.

Endovascular treatment for acute ischaemic stroke with large artery occlusion has become the standard of care. However, the question if a subgroup of patients, with a low cerebral blood volume Alberta Stroke Program Early CT score (CBV-ASPECTS) ≤ 7 should be excluded from endovascular treatment remains open. Therefore; we investigated the difference of outcome between patients who were treated by endovascular treatment vs patients who did not receive endovascular treatment. We retrospectively analysed our stroke database for all patients who presented within six hours of onset with unfavourable imaging findings and who received endovascular treatment or best medical treatment alone. Unfavourable imaging was defined as a CBV-ASPECTS ≤ 7, which was an exclusion criterion for endovascular treatment at our institution before 2015. From 60 patients with an initial CBV-ASPECTS ≤ 7, 40 received best medical treatment and 20 were treated with endovascular treatment. Arterial hypertension and atrial fibrillation was more present in patients without endovascular treatment, the other baseline characteristics and percentage of patients treated with intravenous recombinant tissue plasminogen activator were not significantly different in both groups. At discharge, 40% of the interventional treated patients had a favourable outcome (eight of 20 (40%) vs six of 40 (15%; p = 0.031). The median values of the National Institute of Health Stroke Score and modified Rankin Scale at discharge were significantly lower in the treated cohort (6.5 (2.5-10.5) vs 16 (9.5-22.5); p = 0.006; 3 (0-5.5) vs 5 (4.5-5.5); p = 0.003). Patients with a CBV-ASPECTS ≤ 7 are likely to benefit from therapy and therefore may not be excluded from endovascular treatment. Further randomised trials are warranted to validate the data.

Early computed tomography-based scores to predict decompressive hemicraniectomy after endovascular therapy in acute ischemic stroke.

BackgroundIdentification of patients requiring decompressive hemicraniectomy (DH) after endovascular therapy (EVT) is crucial as clinical signs are not reliable and early DH has been shown to improve clinical outcome. The aim of our study was to identify imaging-based scores to predict the risk for space occupying ischemic stroke and DH.MethodsProspectively derived data from patients with acute large artery occlusion within the anterior circulation and EVT was analyzed in this monocentric study. Predictive value of non-contrast cranial computed tomography (ncCT) and cerebral blood volume (CBV) Alberta Stroke Program Early CT score (ASPECTS) were investigated for DH using logistic regression models and Receiver Operating Characteristic Curve analysis.ResultsFrom 218 patients with EVT, DH was performed in 20 patients (9.2%). Baseline- (7 vs. 9; p = 0.009) and follow-up ncCT ASPECTS (1 vs. 7, p<0.001) as well as baseline CBV ASPECTS (5 vs. 7, p<0.001) were significantly lower in patients with DH. ncCT (baseline: OR 0.71, p = 0.018; follow-up: OR 0.32, p = <0.001) and CBV ASPECTS (OR 0.63, p = 0.008) predicted DH. Cut-off ncCT-ASPECTS on baseline was 7-, ncCT-ASPECTS on follow-up was 4- and CBV ASPECTS on baseline was 5 points.ConclusionsASPECTS could be useful to early identify patients requiring DH after EVT for acute large vessel occlusion.

Low Cerebral Blood Volume Identifies Poor Outcome in Stent Retriever Thrombectomy.

Mechanical thrombectomy (MT) is an efficient treatment of acute stroke caused by large-vessel occlusion. We evaluated the factors predicting poor clinical outcome (3-month modified Rankin Scale, mRS >2) although MT performed with modern stent retrievers. We prospectively collected the clinical and imaging data of 105 consecutive anterior circulation stroke patients who underwent MT after multimodal CT imaging. Patients with occlusion of the internal carotid artery and/or middle cerebral artery up to the M2 segment were included. We recorded baseline clinical, procedural and imaging variables, technical outcome, 24-h imaging outcome and the clinical outcome. Differences between the groups were studied with appropriate statistical tests and binary logistic regression analysis. Low cerebral blood volume Alberta stroke program early CT score (CBV-ASPECTS) was associated with poor clinical outcome (median 7 vs. 9, p=0.01). Lower collateral score (CS) significantly predicted poor outcome in regression modelling with CS=0 increasing the odds of poor outcome 4.4-fold compared to CS=3 (95% CI 1.27-15.5, p=0.02). Lower CBV-ASPECTS significantly predicted poor clinical outcome among those with moderate or severe stroke (OR 0.82, 95% CI 0.68-1, p=0.05) or poor collateral circulation (CS 0-1, OR 0.66, 95% CI 0.48-0.90, p=0.009) but not among those with mild strokes or good collaterals. CBV-ASPECTS estimating infarct core is a significant predictor of poor clinical outcome among anterior circulation stroke patients treated with MT, especially in the setting of poor collateral circulation and/or moderate or severe stroke.

Cerebral Blood Volume ASPECTS Is the Best Predictor of Clinical Outcome in Acute Ischemic Stroke: A Retrospective, Combined Semi-Quantitative and Quantitative Assessment

IntroductionThe capability of CT perfusion (CTP) Alberta Stroke Program Early CT Score (ASPECTS) to predict outcome and identify ischemia severity in acute ischemic stroke (AIS) patients is still questioned.Methods62 patients with AIS were imaged within 8 hours of symptom onset by non-contrast CT, CT angiography and CTP scans at admission and 24 hours. CTP ASPECTS was calculated on the affected hemisphere using cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) maps by subtracting 1 point for any abnormalities visually detected or measured within multiple cortical circular regions of interest according to previously established thresholds. MTT-CBV ASPECTS was considered as CTP ASPECTS mismatch. Hemorrhagic transformation (HT), recanalization status and reperfusion grade at 24 hours, final infarct volume at 7 days and modified Rankin scale (mRS) at 3 months after onset were recorded.ResultsSemi-quantitative and quantitative CTP ASPECTS were highly correlated (p<0.00001). CBF, CBV and MTT ASPECTS were higher in patients with no HT and mRS≤2 and inversely associated with final infarct volume and mRS (p values: from p<0.05 to p<0.00001). CTP ASPECTS mismatch was slightly associated with radiological and clinical outcomes (p values: from p<0.05 to p<0.02) only if evaluated quantitatively. A CBV ASPECTS of 9 was the optimal semi-quantitative value for predicting outcome.ConclusionsOur findings suggest that visual inspection of CTP ASPECTS recognizes infarct and ischemic absolute values. Semi-quantitative CBV ASPECTS, but not CTP ASPECTS mismatch, represents a strong prognostic indicator, implying that core extent is the main determinant of outcome, irrespective of penumbra size.

Collateral Circulation Predicts the Size of the Infarct Core and the Proportion of Salvageable Penumbra in Hyperacute Ischemic Stroke Patients Treated with Intravenous Thrombolysis

Background: We studied the impact of collateral circulation on CT perfusion (CTP) parametric maps and the amount of salvaged brain tissue, the imaging and clinical outcome at 24 h and at 3 months in a retrospective acute (<3 h) stroke cohort (105 patients) with anterior circulation thrombus treated with intravenous thrombolysis. Methods: Baseline clinical and imaging information were collected and groups with different collateral scores (CS) were compared. Binary logistic regression analyses using good CS (CS ≥2) as the dependent variable were calculated. Results: CTP Alberta Stroke Program Early CT Score (ASPECTS) was successfully assessed in 58 cases. Thirty patients displayed good CS. Poor CS were associated with more severe strokes according to National Institutes of Health Stroke Scale (NIHSS) at arrival (15 vs. 7, p = 0.005) and at 24 h (10 vs. 3, p = 0.003) after intravenous thrombolysis. Good CS were associated with a longer mean onset-to-treatment time (141 vs. 121 min, p = 0.009) and time to CTP (102 vs. 87 min, p = 0.047), better cerebral blood volume (CBV) ASPECTS (9 vs. 6, p < 0.001), better mean transit time (MTT) ASPECTS (6 vs. 3, p < 0.001), better noncontrast CT (NCCT) ASPECTS (10 vs. 8, p < 0.001) at arrival and with favorable clinical outcome at 3 months (modified Rankin Scale ≤2, p = 0.002). The fraction of penumbra that was salvageable at arrival and salvaged at 24 h was higher with better CS (p < 0.001 and p = 0.035, respectively). In multivariate analysis, time from the onset of symptoms to imaging (p = 0.037, OR 1.04 per minute, 95% CI 1.00-1.08) and CBV ASPECTS (p = 0.001, OR 2.11 per ASPECTS point, 95% CI 1.33-3.34) predicted good CS. In similar multivariable models, MTT ASPECTS (p = 0.04, OR 1.46 per ASPECTS point, 95% CI 1.02-2.10) and NCCT ASPECTS predicted good CS (p = 0.003, OR 4.38 per CT ASPECTS point, 95% CI 1.66-11.55) along with longer time from the onset of symptoms to imaging (p = 0.045, OR 1.03 per minute, 95% CI 1.00-1.06 and p = 0.02, OR 1.05 per minute, 95% CI 1.00-1.09, respectively). CBV ASPECTS had a larger area under the receiver operating characteristic curve for good CS (0.837) than NCCT ASPECTS (0.802) or MTT ASPECTS (0.752) at arrival. Conclusions: Favorable CBV ASPECTS, NCCT ASPECTS and MTT ASPECTS are associated with good CS along with more salvageable tissue and longer time from the onset of symptoms to imaging in ischemic stroke patients treated with intravenous thrombolysis.

Abstract WP147: Multimodal CT: Favorable Outcome Factors In Acute Middle Cerebral Artery Stroke With Large Artery Occlusion

Background In acute stroke patients with large artery occlusion, we investigated the usefulness of multimodal CT as an initial predictor for a favorable outcome in addition to clinical findings. We studied which parameters of multimodal CT might be the most reliable predictors for favorable outcomes, and combination of these multimodal CT parameters to increase predictive validity, compared to a single parameter. Methods The parameters of multimodal CT, including non-enhanced CT (NECT), CT angiography, perfusion CT parameters, CT angiography source image (CTA-SI), and collateral flow, were analyzed in 66 consecutive patients with acute middle cerebral artery stroke with large artery occlusion. To evaluate the predictive validity of individual parameters for favorable outcome at 3 month follow-up (modified Rankin scale≤ 2), receiver operating characteristic (ROC) curves were generated, and optimum predictive cutoff- Alberta Stroke Program Early CT Score (ASPECTS) was calculated. ROC curves of the individual parameters and their combinations were analyzed by pairwise comparison. As an additional imaging predictor to clinical findings for favorable outcome, crude or adjusted odds ratios of individual parameters, predefined by the optimum predictive cutoff-ASPECTS, were assessed through univariate or multivariate analyses. Results Optimum predictive cutoffs for favorable outcome as follows: CTA-SI ASPECTS ≥ 7, cerebral blood volume (CBV) ASPECTS ≥ 6, NECT ASPECTS ≥ 10, good collateral flow, and cerebral blood flow ASPECTS ≥ 2. On the multivariate analyses, CTA-SI ASPECTS ≥ 7, CBV ASPECTS ≥ 6, and good collateral flow were associated with a favorable outcome. On the ROC analyses by pairwise comparison, the combination of those parameters had better predictive validity compared to a single parameter only: CBV (p = 0.039), CTA-SI (p = 0.038), and collateral flow (p &lt; 0.001). Conclusion Among the various parameters of multimodal CT, CTA-SI ASPECTS ≥ 7, CBV ASPECTS ≥ 6, and good collateral flow might be the most reliable predictors for favorable outcomes in acute stroke patients with large artery occlusion. Moreover, considering these parameters simultaneously might improve the predictive validity of multimodal CT for functional outcome.

Correlation of volumetric mismatch and mismatch of Alberta Stroke Program Early CT Scores on CT perfusion maps

We aimed to determine if volumetric mismatch between tissue at risk and tissue destined to infarct on computed tomography perfusion (CTP) can be described by the mismatch of Alberta Stroke Program Early CT Score (ASPECTS). Forty patients with nonlacunar middle cerebral artery infarct <6 h old who had CTP on admission were retrospectively reviewed. Two raters segmented the lesion volume on mean transit time (MTT) and cerebral blood volume (CBV) maps using thresholds of >6 s and <2.0 mL per 100 g, respectively. Two other raters assigned ASPECTS to the same MTT and CBV maps while blinded to the volumetric data. Volumetric mismatch was deemed present if >or=20%. ASPECTS mismatch (=CBV ASPECTS - MTT ASPECTS) was deemed present if >or=1. Correlation between the two types of mismatches was assessed by Spearman's coefficient (rho). ROC curve analyses were performed to determine the optimal ASPECTS mismatch cut point for volumetric mismatch >or=20%, >or=50%, >or=100%, and >or=150%. Median volumetric mismatch was 130% (range 10.9-2,031%) with 31 (77.5%) being >or=20%. Median ASPECTS mismatch was 2 (range 0-6) with 26 (65%) being >or=1. ASPECTS mismatch correlated strongly with volumetric mismatch with rho = 0.763 [95% CI 0.585-0.870], p < 0.0001. Sensitivity and specificity for volumetric mismatch >or=20% was 83.9% [95% CI 65.5-93.5] and 100% [95% CI 65.9-100], respectively, using ASPECTS mismatch >or=1. Volumetric mismatch >or=50%, >or=100%, and >or=150% were optimally identified using ASPECTS mismatch >or=1, >or=2, and >or=2, respectively. On CTP, ASPECTS mismatch showed strong correlation to volumetric mismatch. ASPECTS mismatch >or=1 was the optimal cut point for volumetric mismatch >or=20%.

Accuracy of the Alberta Stroke Program Early CT Score during the First 3 Hours of Middle Cerebral Artery Stroke: Comparison of Noncontrast CT, CT Angiography Source Images, and CT Perfusion

The Alberta Stroke Program Early CT Score (ASPECTS) is a reliable method of delineating the extent of middle cerebral artery (MCA) stroke. Our aim was to retrospectively compare the accuracy of ASPECTS on noncontrast CT, CT angiography (CTA) source images, and CT perfusion maps of cerebral blood volume (CBV) during the first 3 hours of middle cerebral artery (MCA) stroke. First-time patients with MCA stroke who presented <3 hours from symptom onset and were evaluated by noncontrast CT/CTA/CT perfusion, had confirmed acute nonlacunar MCA infarct on diffusion-weighted MR imaging (DWI) within 7 days, and had follow-up angiography were included. Patients were excluded for persistent MCA occlusion or stenosis. Two raters through consensus assigned an ASPECTS on the noncontrast CT, CTA source images, and the section-selective (2 x 12 mm coverage) CT perfusion CBV maps. ASPECTS on follow-up DWI served as the reference standard. For each CT technique, the detection rates of regional infarction, the mean ASPECTS, and the linear correlation to final ASPECTS were determined and compared. P values <.05 were considered significant. Twenty-eight patients satisfied the criteria with DWI performed at a mean of 50.3 hours (range, 22-125 hours) post-CT imaging. Of 280 ASPECTS regions, 100 were infarcted on DWI. The accuracy of noncontrast CT, CTA source images, and CT perfusion CBV for detecting regional infarct was 80.0%, 84.3%, and 96.8%, respectively (P < .0001). The mean ASPECTSs of noncontrast CT, CTA source images, CT perfusion CBV, and DWI were 8.4 +/- 1.8, 8.0 +/- 1.8, 6.8 +/- 1.9, and 6.5 +/- 1.8, respectively. The mean noncontrast CT and CTA source image ASPECTS was different from that of DWI (P < .05). Correlation of noncontrast CT, CTA source images, and CT perfusion CBV ASPECTS with final ASPECTS was r(2) = 0.34, r(2) = 0.42, and r(2) = 0.91, respectively. In a retrospective cohort of MCA infarcts imaged <3 hours from stroke onset, ASPECTS was most accurately determined on CT perfusion CBV maps.

Alberta Stroke Program Early CT Scoring of CT Perfusion in Early Stroke Visualization and Assessment

Qualitative CT perfusion (CTP) assessment by using the Alberta Stroke Program Early CT Score (ASPECTS) allows rapid calculation of infarct extent for middle cerebral artery infarcts. Published thresholds exist for noncontrast CT (NCCT) ASPECTS, which may distinguish outcome/complication risk, but early ischemic signs are difficult to detect. We hypothesized that different ASPECTS thresholds exist for CTP parameters versus NCCT and that these may be superior at predicting clinical and radiologic outcome in the acute setting. Thirty-six baseline acute stroke NCCT and CTP studies within 3 hours of symptoms were blindly reviewed by 3 neuroradiologists, and ASPECTS were assigned. Treatment response was defined as major neurologic improvement when a > or =8-point National Institutes of Health Stroke Scale improvement at 24 hours occurred. Follow-up NCCT ASPECTS and 90-day modified Rankin score (mRS) were radiologic and clinical reference standards. Receiver operating characteristic curves derived optimal thresholds for outcome. Cerebral blood volume and NCCT ASPECTS had similar radiologic correlations (0.6 and 0.5, respectively) and best predicted infarct size in the absence of major neurologic improvement. A NCCT ASPECT threshold of 7 and a cerebral blood volume threshold of 8 discriminated patients with poor follow-up scans (P < .0002 and P = .0001) and mRS < or =2 (P = .001 and P < .001). Only cerebral blood volume predicted major neurologic improvement (P = .02). Interobserver agreement was substantial (intraclass correlation coefficient, 0.69). Cerebral blood volume ASPECTS sensitivity, specificity, positive predictive value, and negative predictive value for clinical outcome were 60%, 100%, 100%, and 45%, respectively. No patients with cerebral blood volume ASPECTS <8 achieved good clinical outcome. Cerebral blood volume ASPECTS is equivalent to NCCT for predicting radiologic outcome but may have an additional benefit in predicting patients with major neurologic improvement.