Single-phase CT Angiography Research Articles

MRI-based Quantitative Collateral Assessment in Acute Stroke : AComparison with Single-phase CTA in Drip-and-ship Patients with Serial Imaging.

In acute ischemic stroke with large-vessel occlusion (LVO), collateral assessment with single-phase computed tomography angiography (CTA) might underestimate pial collateral supply in aconsiderable proportion of patients. We aimed to compare time-resolved magnetic resonance imaging (MRI)-based quantitative collateral mapping to conventional collateral imaging with CTA. This retrospective single-center study covering aperiod of 6years (2012-2018) included drip-and-ship LVO patients who underwent MR imaging after initial imaging evaluation with CT. For MRI-based collateral assessment, T2*-weighted time series from perfusion-weighted imaging (PWI) were processed to compute aquantitative collateral vessel index (CVIPWI) based on the magnitude of signal variance across the entire acquisition time. CTA-based collateral scores (Tan and Maas) and CVIPWI were investigated in terms of inter-modality associations between collateral measures, as well as their relationships with stroke severity, infarct volume and early functional outcome. The final analysis included n = 56patients (n = 31female, mean age69.9 ± 14.21 years). No significant relationship was found between MR-based quantitative collateral supply (CVIPWI) and CT-based collateral scores (r = -0.00057, p = 0.502 and r = -0.124, p = 0.797). In contrast to CVIPWI, CTA-based collateral scores showed no significant relationship with clinical stroke severity and infarct volume. While MR-based CVIPWI was independently associated with favorable early functional outcome in multivariate analysis (OR 1.075, 95% CI 1.001-1.153, p = 0.046), CTA-based collateral scores were not significantly associated with outcome. Since collateral scores based on single-phase CTA do not accurately reflect infarct progression and might underestimate pial collateralization in arelevant proportion of patients, they are not associated with early functional outcome in LVO patients. In contrast, CVIPWI represents arobust imaging parameter of collateral supply and is independently associated with functional outcome.

Association between ischaemic stroke aetiology and leptomeningeal collateral status: a retrospective cohort study.

There is limited understanding of the pathomechanistic relationship between leptomeningeal collateral formation and ischaemic stroke aetiology. We aimed to assess the association of leptomeningeal collateral status and ischaemic stroke aetiology, using the widely recognised "Trial of Org 10172 in Acute Stroke Treatment" (TOAST) classification categorising strokes into five distinct aetiologies. Retrospective study of consecutively admitted adult ischaemic stroke patients at a Swiss stroke centre. Leptomeningeal collateral status was assessed on admission with single-phase CT-angiographies using a validated 4-point score. Patients were categorised into large-artery atherosclerosis (LAA), cardioembolic (CE), small-vessel disease (SVD) and cryptogenic (CG) according to the TOAST classification. We performed ordinal and binary (poor [collaterals filling ≤50% of the occluded territory] vs good [collaterals filling >50% of the occluded territory] collateralisation) logistic regression to evaluate the impact of TOAST aetiology on collateral status. Among 191 patients, LAA patients had better collateral status compared to non-LAA aetiology (LAA: 2 vs CE: 2 vs SVD: 3 vs CG: 2, pLAAvsnon-LAA= 0.04). In weighted multivariate logistic regression, LAA and SVD independently predicted better collateral status (binary models [adjusted odds ratio; aOR]: LAA: 3.72 [1.21-11.44] and SVD: 4.19 [1.21-14.52]; ordinal models [adjusted common odds ratio; acOR]: LAA: 2.26 [95% CI: 1.23-4.15] and SVD: 1.94 [1.03-3.66]), while CE predicted worse collateral status (binary models [aOR]: CE: 0.17 [0.07-0.41]; ordinal models [acOR]: CE: 0.24 [0.11-0.51]). The aetiology of ischaemic stroke is associated with leptomeningeal collateral status on single-phase CT-angiography, with LAA and SVD predicting better and CE predicting worse collateral status.

Prediction of tissue outcome in acute ischemic stroke based on single-phase CT angiography at admission.

In acute ischemic stroke, prediction of the tissue outcome after reperfusion can be used to identify patients that might benefit from mechanical thrombectomy (MT). The aim of this work was to develop a deep learning model that can predict the follow-up infarct location and extent exclusively based on acute single-phase computed tomography angiography (CTA) datasets. In comparison to CT perfusion (CTP), CTA imaging is more widely available, less prone to artifacts, and the established standard of care in acute stroke imaging protocols. Furthermore, recent RCTs have shown that also patients with large established infarctions benefit from MT, which might not have been selected for MT based on CTP core/penumbra mismatch analysis. All patients with acute large vessel occlusion of the anterior circulation treated at our institution between 12/2015 and 12/2020 were screened (N = 404) and 238 patients undergoing MT with successful reperfusion were included for final analysis. Ground truth infarct lesions were segmented on 24 h follow-up CT scans. Pre-processed CTA images were used as input for a U-Net-based convolutional neural network trained for lesion prediction, enhanced with a spatial and channel-wise squeeze-and-excitation block. Post-processing was applied to remove small predicted lesion components. The model was evaluated using a 5-fold cross-validation and a separate test set with Dice similarity coefficient (DSC) as the primary metric and average volume error as the secondary metric. The mean ± standard deviation test set DSC over all folds after post-processing was 0.35 ± 0.2 and the mean test set average volume error was 11.5 mL. The performance was relatively uniform across models with the best model according to the DSC achieved a score of 0.37 ± 0.2 after post-processing and the best model in terms of average volume error yielded 3.9 mL. 24 h follow-up infarct prediction using acute CTA imaging exclusively is feasible with DSC measures comparable to results of CTP-based algorithms reported in other studies. The proposed method might pave the way to a wider acceptance, feasibility, and applicability of follow-up infarct prediction based on artificial intelligence.

Absent leptomeningeal collateralization is associated with greatest benefit from mechanical thrombectomy in the 6-24 hour time window.

The impact of leptomeningeal collateralization on the efficacy of mechanical thrombectomy (MT) in patients with anterior circulation large vessel occlusion (aLVO) presenting in the 6-24 h time window remains poorly elucidated. Retrospective multicenter study of aLVO patients presenting between 6 and 24 h after stroke onset who received MT plus Best Medical Treatment (BMT) or BMT alone. Leptomeningeal collateralization was assessed using single-phase computed tomography angiography (grade 0: no filling; grade 1: filling ⩽50%; grade 2: filling >50% but <100%; grade 3: filling 100% of the occluded territory). Inverse probability of treatment weighted ordinal regression was performed to assess the association between treatment and shift of the modified Rankin Scale (mRS) score toward lower categories at 3 months. We used interaction analysis to explore differential treatment effects on functional outcomes (probabilities for each mRS subcategory at 3 months) at different collateral grades. Among 363 included patients, 62% received MT + BMT. Better collateralization was associated with better functional outcomes at 3 months in the BMT alone group (collateral grade 1 vs 0: acOR 5.06, 95% CI 2.33-10.99). MT + BMT was associated with higher odds of favorable functional outcome at 3 months (acOR 1.70, 95% CI 1.11-2.62) which was consistent after adjustment for collateral status (acOR 1.54, 95% CI 1.01-2.35). Regarding treatment effect modification, patients with absent collateralization had higher probabilities for a mRS of 0-4 and a lower mortality at 3 months for the MT + BMT group. In the 6-to-24-h time window, aLVO patients with absent leptomeningeal collateralization benefit most from MT + BMT, indicating potential advantages for this group despite their poorer baseline prognosis.

Enhancing the clinical value of single-phase computed tomography angiography in the assessment of collateral circulation in acute ischemic stroke: A narrative review.

Acute ischemic stroke (AIS) condition assessment and clinical prognosis are significantly influenced by the compensatory state of cerebral collateral circulation. A standard clinical test known as single-phase computed tomography angiography (sCTA) is useful for quickly and accurately assessing the creation or opening of cerebral collateral circulation, which is crucial for the diagnosis and treatment of AIS. To improve the clinical application of sCTA in the clinical assessment of collateral circulation, we examine the present use of sCTA in AIS in this work.

Efficacy of collateral circulation analysis by single-phase CT angiography for acute large vessel occlusion

Efficacy of collateral circulation analysis by single-phase CT angiography for acute large vessel occlusion

Proposed Protocols for Artificial Intelligence Imaging Database in Acute Stroke Imaging.

To propose standardized and feasible imaging protocols for constructing artificial intelligence (AI) database in acute stroke by assessing the current practice at tertiary hospitals in South Korea and reviewing evolving AI models. A nationwide survey on acute stroke imaging protocols was conducted using an electronic questionnaire sent to 43 registered tertiary hospitals between April and May 2021. Imaging protocols for endovascular thrombectomy (EVT) in the early and late time windows and during follow-up were assessed. Clinical applications of AI techniques in stroke imaging and required sequences for developing AI models were reviewed. Standardized and feasible imaging protocols for data curation in acute stroke were proposed. There was considerable heterogeneity in the imaging protocols for EVT candidates in the early and late time windows and posterior circulation stroke. Computed tomography (CT)-based protocols were adopted by 70% (30/43), and acquisition of noncontrast CT, CT angiography and CT perfusion in a single session was most commonly performed (47%, 14/30) with the preference of multiphase (70%, 21/30) over single phase CT angiography. More hospitals performed magnetic resonance imaging (MRI)-based protocols or additional MRI sequences in a late time window and posterior circulation stroke. Diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) were most commonly performed MRI sequences with considerable variation in performing other MRI sequences. AI models for diagnostic purposes required noncontrast CT, CT angiography and DWI while FLAIR, dynamic susceptibility contrast perfusion, and T1-weighted imaging (T1WI) were additionally required for prognostic AI models. Given considerable heterogeneity in acute stroke imaging protocols at tertiary hospitals in South Korea, standardized and feasible imaging protocols are required for constructing AI database in acute stroke. The essential sequences may be noncontrast CT, DWI, CT/MR angiography and CT/MR perfusion while FLAIR and T1WI may be additionally required.

Multiphase computed tomography angiography derived from computed tomography perfusion data for the differential diagnosis of intracranial aneurysm and infundibular dilation.

As infundibular dilation (ID) is less likely to cause hemorrhage or other clinical sequelae than an intracranial aneurysm (IA) and treating infundibulum itself may put the patient at unnecessary risk for stroke, it is important to distinguish between the ID and IA. Given the limitations of conventional single-phase computed tomography angiography (sCTA) to show small branches of intracranial arteries, the application of multiphase computed tomography angiography (mCTA) for identification seems promising. Our main objective was to evaluate whether using mCTA derived from computed tomography perfusion (CTP) data can improve distinction between IA and ID. A total of 35 patients diagnosed with IA or ID of the posterior communicating artery at its junction with the internal carotid artery junction (ICA-PComA) by sCTA at the 8th Medical Center of Chinese PLA General Hospital between January 2019 and May 2022 were retrospectively selected. All patients underwent CTP. The simulated mCTA was reconstructed from 0.75 mm CTP data for assessment of vascular branches. All data were processed separately by 2 CTA post-processors; 2 observers diagnosed IA and ID by source and volume rendering (VR) images of sCTA and VR images of mCTA, and compared the diagnostic efficacy of source and VR images of sCTA with VR images of mCTA. The quality of the reconstructed images was more consistent between the 2 post-processors mCTA (K=0.856) than sCTA (K=0.648). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the source image for ID identification were 78.9%, 86.7%, 84.2%, 81.3%, and 80.0% for sCTA, 73.7%, 81.2%, 82.3%, 72.2%, and 77.2% for the VR image of sCTA, and 94.7%, 87.5%, 90.0%, 93.3%, and 91.4% for the VR image based on mCTA, respectively. The net reclassification index (NRI) of mCTA for VR and the source image of sCTA was 0.273 and 0.220, respectively. VR base on mCTA was on average better than VR and the source image of sCTA at differentiating ID from IA (P=0.005 and P=0.001, respectively). Compared to sCTA, mCTA is more helpful in improving the distinction of ID and IA.

Single vs. Multiphase Computed Tomography angiography in acute internal carotid artery occlusion: An accuracy and interobserver agreement study

ObjectiveAccurate differentiation between the intracranial and extracranial location of the acute internal carotid artery (ICA) occlusion is essential for guiding treatment decisions and mechanical thrombectomy planning. Multiphase Computed Tomography angiography (mCTA) appears to be superior to Single-phase Computed Tomography angiography (sCTA) in the evaluation of acute ICA occlusions. The main objective of our research is to study the accuracy of mCTA compared to sCTA in distinguishing isolated acute intracranial ICA occlusion from extracranial or tandem occlusion. MethodsTwo observers independently analyzed sCTA and mCTA of patients with acute ICA occlusion at two different time points. The location of the occlusion was categorized as intracranial or extracranial for both imaging techniques and then compared with digital subtraction angiography (gold standard). Sensitivity and specificity rates for isolated intracranial ICA occlusion on sCTA and mCTA were calculated. Kappa statistics were used to assess interobserver agreement. ResultsThe sensitivity of sCTA and mCTA was 48.28% (28.36%–68.19%) and 79.31% (62.84%–95.78%) respectively for the diagnosis of isolated intracranial ICA occlusion, with an almost perfect interobserver agreement between both observers (p < 0.001). ConclusionsOur research suggests that mCTA is more accurate than sCTA in distinguishing isolated intracranial occlusions from extracranial or tandem occlusions.

The association between cortical venous outflow and futile recanalization in patients with acute ischemic stroke due to large vessel occlusion in the anterior circulation

Objective: To explore the association of baseline venous outflow (VO) profile with futile recanalization in patients with acute ischemic stroke due to large vessel occlusion in the anterior circulation. Methods: The clinical and imaging data of patients presented with large vessel occlusion in the anterior circulation and underwent emergency endovascular treatment at Huashan Hospital from March 2015 to December 2021 were retrospectively included in the study. All patients were assessed by the National Institutes of Health Stroke Scale (NIHSS) at baseline.Baseline VO profile was determined by a 0-6 semi-quantitative scoring system which assessed opacification of the ipsilateral superficial middle cerebral vein, vein of Labbé and vein of Trolard on single-phase CT angiography (CTA) images. A 90-day telephone follow-up was performed and functional outcome was evaluated by 90 d modified Rankin scale (mRS). Successful recanalization of the occluded artery, defined as final modified Thrombolysis in Cerebral Infarction scale (mTICI) 2b-3, was considered to be futile if patients failed to achieve functional independence (90 d mRS 0-2). Univariate analysis and receiver operating characteristic (ROC) curve analysis were used to explore the optimal cutoff predicting functional indendence. The associations between cortical VO in ischemic area and futile recanalization were evaluated using binary logistic regression analysis and backward linear regression based on Akaike information criterion (AIC). Results: A total of 150 patients met the inclusion criteria, with 92 males (61.3%) and 58 females (38.7%). The median age [M(Q1, Q3)]was 71 (61, 78) years and the median baseline National Institute of Health Stroke Scale (NIHSS) score [M(Q1, Q3)]was 15 (11, 18). Univariate logistic regression analysis showed that baseline VO was associated with 90-day functional independence (OR=1.587, 95%CI: 1.185-2.1873). After classifying VO into two categories based on the receiver operating characteristic (ROC) curve, VO≥4 showed an independent association with functional independence (OR=5.133, 95%CI: 1.530-9.361) after adjusting for age, baseline glucose, NIHSS score, baseline infarct core volume, modified Tan (mTan) score, hypoperfusion intensity ratio (HIR), etiological classification, recanalization, presence of any hemorrhagic transformation and final infarct volume. Futile recanalization was observed in 44 (48.4%) of the 91 patients who achieved successful recanalization. Stepwise logistic regression revealed that VO≥4 was an independent protective factor for futile recanalization (OR=0.234, 95%CI: 0.054-0.878). Moreover, in patients with mTICI 2c-3, VO≥4 showed a stronger association with futile recanalization (OR=0.018, 95%CI: 0-0.255). Conclusion: A favorable VO profile at onset protects against futile recanalization in patients with large vessel occlusion in the anterior circulation, and provides a simple and feasible auxiliary method for predicting the prognosis of endovascular therapy in such patients.

Radiomics Based on Single-Phase CTA for Distinguishing Left Atrial Appendage Thrombus from Circulatory Stasis in Patients with Atrial Fibrillation before Ablation.

Differentiation of left atrial appendage thrombus (LAAT) and left atrial appendage (LAA) circulatory stasis is difficult when based only on single-phase computed tomography angiography (CTA) in routine clinical practice. Radiomics provides a promising tool for their identification. We retrospectively enrolled 204 (training set: 144; test set: 60) atrial fibrillation patients before ablation, including 102 LAAT and 102 circulatory stasis patients. Radiomics software was used to segment whole LAA on single-phase CTA images and extract features. Models were built and compared via a multivariable logistic regression algorithm and area under of the receiver operating characteristic curves (AUCs), respectively. For the radiomics model, radiomics clinical model, radiomics radiological model, and combined model, the AUCs were 0.82, 0.86, 0.90, 0.93 and 0.82, 0.82, 0.84, 0.85 in the training set and the test set, respectively (p < 0.05). One clinical feature (rheumatic heart disease) and four radiological features (transverse diameter of left atrium, volume of left atrium, location of LAA, shape of LAA) were added to the combined model. The combined model exhibited excellent differential diagnostic performances between LAAT and circulatory stasis without increasing extra radiation exposure. The single-phase, CTA-based radiomics analysis shows potential as an effective tool for accurately detecting LAAT in patients with atrial fibrillation before ablation.

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.

Abstract TP120: Noncontrast Ct, Single-phase Cta, And Multiphase Cta Intracerebral Hemorrhage Expansion Scores

Background: Several noncontrast computed tomography (NCCT), single-phase computed tomography angiography (CTA), and multiphase CTA markers of intracerebral hemorrhage (ICH) expansion have been previously proposed. We derived and validated three scores for the prediction of hematoma expansion depending on the use of NCCT, single-phase CTA, or multiphase CTA markers of hematoma expansion. Methods: We prospective studied 276 consecutive patients with ICH within 6 hours from symptom onset. After deriving NCCT, single-phase CTA, and multiphase CTA scores in a 5-year period population (n=156), we validated them in a different 3-year period population (n=120). Outcome parameters included substantial hematoma expansion &gt;6 mL or &gt;33% at 24 hours (primary outcome) and poor outcome (mRS score &gt;2) at 90 days. Results: The most accurate marker of hematoma expansion was spot sign in phase 1 of multiphase CTA (80.3%). The four independent predictors of substantial hematoma expansion included in the different scores were ultraearly hematoma growth (uHG) &gt;5 mL/h, heterogeneous density, spot sign in phase 1 of multiphase CTA, and spot sign in any phase of multiphase CTA (Table). On each of the three scores, the proportion of patients that experienced substantial hematoma expansion increased with each point increase. C-index for both substantial hematoma expansion and poor outcome in the derivation and validation cohort was lower in NCCT expansion score than in single-phase CTA expansion score which, in turn, was lower than in multiphase CTA expansion score (Table). Conclusions: This study demonstrates the added prognostic value of more advanced CT modalities in acute ICH evaluation. Single-phase CTA score and, especially, multiphase CTA score, are more robust than NCCT score in the prediction of hematoma expansion and poor outcome. These scores may help to refine the selection of patients at risk of expansion and poorest outcomes in different decision-making scenarios.

Effect of collateral level in CT angiography on clinical prognosis in stroke patients treated with mechanical thrombectomy after six hours

Objectives: Collaterals have an effect on the protection of penumbra tissue. We evaluated the effect of collaterals on single-phase computed tomography angiography (CTA) in patients with AIS treated with MT after 6 hours. Methods: We evaluated patients with ICA or M1 segment of MCA occlusion, time of symptom-groin puncture &gt;6 hours, having CTA before MT, modified Treatment In Cerebral Ischemia score (mTICI) 2b-3 recanalization after MT. Data of collateral levels, outcome measures, timings and other variables were collected from Turkish Interventional Neurology Database. The level of collaterals was assessed with modified Tan scale. Results: A total of 57 patients were included in our study. The median age was 64[56.5-75] years. The median NIHSS score at onset was 15[12-17.5] points. A total of 33 (57.9%) patients had good collaterals on CTA. Hypertension (HT) and diabetes mellitus (DM) rates were increased in the poor collaterals group. NIHSS scores decreased at the 24th hour in both good and poor collaterals groups. Twenty-two (66.7%) patients in the good collaterals group and 11 (45.8%) patients in the poor collaterals group had good clinical outcomes. However, there was not a significant difference (p=0.174, OR: 2.364; 95% CI: 0.802-6.697). Mortality rates were different in both groups, but the difference was not found to be significant (5[15.2%] versus 8[33.3%], p=0.124, OR:0.357; 95% CI: 0.1-1.278). Conclusion: Good collaterals on single-phase CTA was not associated with improved neurological outcomes in AIS patients treated after 6 hours.

Single-phase CT angiography predicts ASPECTS decay and may help determine when to repeat CT before thrombectomy

ObjetivesTime is relative in large-vessel occlusion acute ischemic stroke (LVO-AIS). We aimed to evaluate the rate of inter-hospital ASPECTS decay in patients transferred from a primary (PSC) to a comprehensive stroke center (CSC); and to identify patients that should repeat computed tomography (CT) before thrombectomy. Materials and methodsThis was a retrospective cohort study of consecutive anterior circulation LVO-AIS transferred patients. The rate of ASPECTS decay was defined as (PSC-ASPECTS – CSC-ASPECTS)/hours elapsed between scans. Single-phase CT angiography (CTA) at the PSC was used to classify the collateral score. We compared patients with futile versus useful CT scan re-evaluation. ResultsWe included 663 patients, of whom 245 (37.0%) repeated CT at a CSC. The median rate of ASPECTS decay was 0.4/h (0.0-0.9). Patients excluded from thrombectomy after a CT scan repeat (n=64) had a median ASPECTS decay rate of 1.18/h (0.83-1.61). Patients with absent collateral circulation had a median rate of 1.51(0.65-2.19). The collateral score was an independent predictor of the ASPECTS decay rate (aβ = -0.35; 95%CI -0.45 - -0.19, p<0.001). Age (aOR: 1.04 95% CI 1.02-1.07, p<0.001), NIHSS (aOR: 1.11 95% CI 1.06-1.15, p<0.001), PSC ASPECTS (aOR: 0.74 95% CI 0.60-0.91, p=0.006) and the CTA collateral score (aOR: 0.14 95% CI 0.08-0.22, p<0.001) were independent predictors of the usefulness of a CT scan repeat. ConclusionsThe rate of ASPECTS decay can be predicted by the CTA collateral score, helping in the selection of patients that would benefit from repeating a CT assessment on arrival at the CSC.

Automated scoring of collaterals, blood pressure, and clinical outcome after endovascular treatment in patients with acute ischemic stroke and large-vessel occlusion.

IntroductionWe aimed to determine whether the degree of collateral circulation is associated with blood pressure at admission in acute ischemic stroke patients treated with endovascular treatment and to determine its prognostic value.MethodsWe evaluated patients with anterior large vessel occlusion treated with endovascular treatment in a single-center prospective registry. We collected clinical and radiological data. Automated and validated software (Brainomix Ltd., Oxford, UK) was used to generate the collateral score (CS) from the baseline single-phase CT angiography: 0, filling of ≤10% of the occluded MCA territory; 1, 11–50%; 2, 51–90%; 3, >90%. When dichotomized, we considered that CS was good (CS = 2–3), or poor (CS = 0–1). We performed bivariate and multivariable ordinal logistic regression analysis to predict CS categories in our population. The secondary outcome was to determine the influence of automated CS on functional outcome at 3 months. We defined favorable functional outcomes as mRS 0–2 at 3 months.ResultsWe included 101 patients with a mean age of 72.1 ± 13.1 years and 57 (56.4%) of them were women. We classified patients into 4 groups according to the CS: 7 patients (6.9%) as CS = 0, 15 (14.9%) as CS = 1, 43 (42.6%) as CS = 2 and 36 (35.6%) as CS = 3. Admission systolic blood pressure [aOR per 10 mmHg increase 0.79 (95% CI 0.68–0.92)] and higher baseline NIHSS [aOR 0.90 (95% CI, 0.84–0.96)] were associated with a worse CS. The OR of improving 1 point on the 3-month mRS was 1.63 (95% CI, 1.10–2.44) favoring a better CS (p = 0.016).ConclusionIn acute ischemic stroke patients with anterior large vessel occlusion treated with endovascular treatment, admission systolic blood pressure was inversely associated with the automated scoring of CS on baseline CT angiography. Moreover, a good CS was associated with a favorable outcome.

Alberta Stroke Program Early CT Score and collateral status predict target mismatch in large vessel occlusion with delayed time windows

BackgroundThe Alberta Stroke Program Early CT Score (ASPECTS) and collateral score (CS) are two readily available imaging metrics for the evaluation of acute ischemic stroke (AIS) with large vessel occlusion...

Should Primary Stroke Centers Perform Advanced Imaging?

Should Primary Stroke Centers Perform Advanced Imaging?

Quantification of infarct core signal using CT imaging in acute ischemic stroke

In stroke care, the extent of irreversible brain injury, termed infarct core, plays a key role in determining eligibility for acute treatments, such as intravenous thrombolysis and endovascular reperfusion therapies. Many of the pivotal randomized clinical trials testing those therapies used MRI Diffusion-Weighted Imaging (DWI) or CT Perfusion (CTP) to define infarct core. Unfortunately, these modalities are not available 24/7 outside of large stroke centers. As such, there is a need for accurate infarct core determination using faster and more widely available imaging modalities including Non-Contrast CT (NCCT) and CT Angiography (CTA).Prior studies have suggested that CTA provides improved predictions of infarct core relative to NCCT; however, this assertion has never been numerically quantified by automatic medical image computing pipelines using acquisition protocols not confounded by different scanner manufacturers, or other protocol settings such as exposure times, kilovoltage peak, or imprecision due to contrast bolus delays. In addition, single-phase CTA protocols are at present designed to optimize contrast opacification in the arterial phase. This approach works well to maximize the sensitivity to detect vessel occlusions, however, it may not be the ideal timing to enhance the ischemic infarct core signal (ICS).In this work, we propose an image analysis pipeline on CT-based images of 88 acute ischemic stroke (AIS) patients drawn from a single dynamic acquisition protocol acquired at the acute ischemic phase. We use the first scan at the time of the dynamic acquisition as a proxy for NCCT, and the rest of the scans as a proxy for CTA scans, with bolus imaged at different brain enhancement phases. Thus, we use the terms “NCCT” and “CTA” to refer to them. This pipeline enables us to answer the questions “Does the injection of bolus enhance the infarct core signal?” and “What is the ideal bolus timing to enhance the infarct core signal?” without being influenced by aforementioned factors such as scanner model, acquisition settings, contrast bolus delay, and human reader errors. We use reference MRI DWI images acquired after successful recanalization acting as our gold standard for infarct core.The ICS is quantified by calculating the difference in intensity distribution between the infarct core region and its symmetrical healthy counterpart on the contralateral hemisphere of the brain using a metric derived from information theory, the Kullback-Leibler divergence (KL divergence). We compare the ICS provided by NCCT and CTA and retrieve the optimal timing of CTA bolus to maximize the ICS.In our experiments, we numerically confirm that CTAs provide greater ICS compared to NCCT. Then, we find that, on average, the ideal CTA acquisition time to maximize the ICS is not the current target of standard CTA protocols, i.e., during the peak of arterial enhancement, but a few seconds afterward (median of 3 s; 95% CI [1.5, 3.0]). While there are other studies comparing the prediction potential of ischemic infarct core from NCCT and CTA images, to the best of our knowledge, this analysis is the first to perform a quantitative comparison of the ICS among CT based scans, with and without bolus injection, acquired using the same scanning sequence and a precise characterization of the bolus uptake, hence, reducing potential confounding factors.

Interrater Agreement and Detection Accuracy for Medium-Vessel Occlusions Using Single-Phase and Multiphase CT Angiography.

Accurate and reliable detection of medium-vessel occlusions is important to establish the diagnosis of acute ischemic stroke and initiate appropriate treatment with intravenous thrombolysis or endovascular thrombectomy. However, medium-vessel occlusions are often challenging to detect, especially for unexperienced readers. We aimed to evaluate the accuracy and interrater agreement of the detection of medium-vessel occlusions using single-phase and multiphase CTA. Single-phase and multiphase CTA of 120 patients with acute ischemic stroke (20 with no occlusion, 44 with large-vessel occlusion, and 56 with medium-vessel occlusion in the anterior and posterior circulation) were assessed by 3 readers with varying levels of experience (session 1: single-phase CTA; session 2: multiphase CTA). Interrater agreement for occlusion type (large-vessel occlusion versus medium-vessel occlusion versus no occlusion) and for detailed occlusion sites was calculated using the Fleiss κ with 95% confidence intervals. Accuracy for the detection of medium-vessel occlusions was calculated for each reader using classification tables. Interrater agreement for occlusion type was moderate for single-phase CTA (κ = 0.58; 95% CI, 0.56-0.62) and almost perfect for multiphase CTA (κ = 0.81; 95% CI, 0.78-0.83). Interrater agreement for detailed occlusion sites was moderate for single-phase CTA (κ = 0.55; 95% CI, 0.53-0.56) and substantial for multiphase CTA (κ = 0.71; 95% CI, 0.67-0.74). On single-phase CTA, readers 1, 2, and 3 classified 33/56 (59%), 34/56 (61%), and 32/56 (57%) correctly as medium-vessel occlusions. On multiphase CTA, 48/56 (86%), 50/56 (89%), and 50/56 (89%) medium-vessel occlusions were classified correctly. Interrater agreement for medium-vessel occlusions is moderate when using single-phase CTA and almost perfect with multiphase CTA. Detection accuracy is substantially higher with multiphase CTA compared with single-phase CTA, suggesting that multiphase CTA might be a valuable tool for assessment of medium-vessel occlusion stroke.