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Introduction by the Convenors
OPTIMISING THE DEFINITION OF INFARCT CORE IN CT-PERFUSION: INFLUENCE OF INFARCT GROWTH AND WHITE/GREY MATTER SPECIFIC THRESHOLDS
Abstract
Background And Aims
Infarct core measured using CT-perfusion (CTP) has limited accuracy compared to DWI-MRI. We studied the effect of applying white matter (WM) and grey matter (GM) specific thresholds and accounting for infarct growth (IG) from baseline imaging to reperfusion over the predictive yield of CTP definitions of infarct core.
Methods
Single-center cohort of consecutive patients (n=113) with witnessed strokes due to proximal occlusions in the carotid territory with baseline CTP, full endovascular reperfusion, and follow-up DWI-MRI. We segmented GM and WM and co-registered CTP with DWI and compared the accuracy of the different predictions for each DWI voxel. We assessed the yield of different relative CBF thresholds to predict the final infarct volume and an estimated IG-corrected volume for a single rCBF threshold and GM/WM-specific thresholds.
Results
The fixed threshold underestimated GM lesions and overestimated WM core (figure 1). The closest estimations of the final DWI infarct were based on rCBF of 25% for a single threshold, 35% for GM, and 20% for WM, and decreased when correcting for IG: 20% for a single threshold, 25% for GM, and 15% for WM. The combination of 25% for GM and 15% for WM was the most accurate for IG-corrected ischemic core and the best predictor of functional outcome.
Conclusions
Moving from uniform to GM and WM-specific thresholds changes the definition of infarct core in CTP and increases the accuracy of the predictions regarding each voxel's fate and total infarct volume. More restrictive thresholds may better estimate the actual extent of the infarcted tissue.
Trial Registration Number
Not applicable
ASSOCIATION BETWEEN COMPUTED TOMOGRAPHY CHARACTERISTICS AND HISTOLOGICAL THROMBUS COMPOSITION IN PATIENTS WITH ACUTE ISCHEMIC STROKE
Abstract
Group Name
on behalf of the MR CLEAN Registry Investigators
Background And Aims
Studies have shown that histological thrombus composition is related to success of endovascular thrombectomy (EVT) for acute ischemic stroke. Computed tomography (CT) characteristics have been suggested useful for the prediction of thrombus composition prior to EVT, however data on this topic is limited. We aimed to assess the association of admission CT characteristics with thrombus composition in patients treated with EVT for acute ischemic stroke.
Methods
For 332 patients enrolled in the MR CLEAN Registry between March 2014 and June 2016, thrombi were histologically analyzed with Hematoxylin-Eosin staining and quantified for percentages of red blood cells (RBCs) and fibrin/platelets. The association of hyperdense artery sign (HAS), thrombus location and clot burden score (CBS) with both components was estimated with univariable and multivariable linear regression. Additionally, for a subgroup of 94 patients with available thin-section (≤2.5mm) imaging, the association of (relative) thrombus density, thrombus length, perviousness, and distance from the ICA-terminus with composition was estimated similarly. The proportion of variance in thrombus composition explained by all CT characteristics together was quantified with R2.
Results
Presence of HAS, a more proximal thrombus location, lower CBS, increased thrombus density, increased thrombus length and decreased perviousness were associated with increased RBC-content and decreased fibrin/platelet-content (Table). R2 of all CT characteristics was 0.30 for RBCs and 0.29 for fibrin/platelets.
Conclusions
In patients undergoing EVT for AIS, admission CT characteristics are strongly associated with thrombus composition. Furthermore, about 30% of the variance in thrombus composition could be predicted by admission CT characteristics.
MRI OR CT FOR SUSPECTED ACUTE STROKE: ASSOCIATION OF ADMISSION IMAGE MODALITY WITH ACUTE RECANALIZATION THERAPIES, WORKFLOW METRICS AND OUTCOMES
Abstract
Group Name
Investigators of the Swiss Stroke Registry
Background And Aims
According to guidelines, both CT and MRI may be used as initial imaging for suspected acute stroke. However, there is no reliable data on the impact of baseline imaging modality on management consequences including rates of intravenous thrombolysis (IVT), mechanical thrombectomy (MT), workflow metrics and functional outcome.
Methods
Observational cohort from 2014 to 2020, using the national Swiss Stroke Registry. Inclusion criteria were admission within 24 hours after symptom onset to a stroke unit or stroke center that used each modality for at least 10% of initial imaging. Exclusion criteria included MRI contraindications, transfer patients, unstable or frail patients.
Results
Of 11049 patients included (mean [SD] age, 71 [15] years; 4811 females [44%]), 3466 (34%) received MRI and 7308 (66%) CT as baseline imaging modality. The rate of angiography (93% vs 94%, P=0.311) was similar, but perfusion imaging (56% vs 67%, P<0.001) was performed less frequently in MRI patients. Admission MRI was associated with lower adjusted odds of use of IVT (aOR 0.83, CI 0.73–0.96), but had no association with use of MT (aOR 1.11, 0.93–1.34). MRI imaging was associated with longer adjusted door to needle times (+13min, [8-18]), but not with longer door to groin times. There was no difference in the odds of symptomatic intracranial hemorrhage (aOR 0.86. 0.57–1.30).
Conclusions
There is an association of MRI with lower rates of IVT, and a slight delay in door to needle time. Considering clinical equipoise, only randomized controlled trials can clarify whether the temporal benefits of CT outweigh the tissue-based benefits of MRI.
COMBINED EFFECT OF CTP ISCHEMIC CORE VOLUME AND AGE ON FUNCTIONAL OUTCOME AFTER ENDOVASCULAR THROMBECTOMY IN THE MR CLEAN REGISTRY
Abstract
Group Name
for the MR CLEAN Registry Investigators
Background And Aims
Patient age and CT perfusion (CTP) ischemic core volume are both independent predictors of outcome in anterior circulation acute ischemic stroke patients treated with endovascular thrombectomy (EVT). We aim to determine the combined effect of age and CTP ischemic core volume on clinical outcome.
Methods
Patients from the MR CLEAN Registry (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands; March 2016–November 2017) with baseline CTP who presented in the early window were included. CTP data were processed using syngo.via (core=CBV<1.2mL/100g). Multivariable ordinal logistic regression was performed to determine the association between continuous age and CTP core volume and shift towards better functional outcome on modified Rankin Scale score (mRS). Subsequently, patients were stratified by age (<71 vs ≥71 years, median) and CTP ischemic core volume (<50 vs ≥ 50mL). Outcomes in the four resulting patient subgroups were compared.
Results
In 201 patients, there was no interaction between age and CTP ischemic core volume on functional outcome (p=0.25). The acOR for continuous age and CTP ischemic core volume was 0.96 per year (95% CI: 0.94-0.98) and 0.85 per 10mL (95% CI: 0.78-0.94), respectively. The subgroup of patients ≥ 71 years with CTP ischemic core volume ≥ 50 mL showed highest frequency of mRS 3-6 (21/22, 95%).
Conclusions
In our population, the effect of CTP ischemic core volume did not differ with patient age. Patients ≥ 71 with CTP ischemic core volumes ≥ 50 mL more often have poor functional outcome after EVT.
Trial Registration Number
Not applicable
ASSOCIATION OF THROMBUS DENSITY IN PATIENTS WITH M1 OCCLUSIONS WITH OUTCOME
Abstract
Group Name
MR CLEAN Registry investigators
Background And Aims
The association of thrombus density with reperfusion and functional outcome remains conflicted in acute ischemic stroke. We evaluated if hyperdense thrombi were associated with reperfusion and functional outcome after endovascular treatment (EVT).
Methods
Thrombus imaging characteristics were measured in patients with M1 occlusions included in the MR CLEAN Registry. Thrombus density was measured on thin-slice (<2.5 mm) non-contrast computed tomography. Based on median density across the dataset, hyperdense thrombi were defined as thrombi >50 Hounsfield Units (HU). Regression models were used to investigate the association between hyperdense thrombi, successful reperfusion (expanded Treatment In Cerebral Ischemia (eTICI) score 2B-3), and favorable and excellent functional outcome (modified Rankin Scale (mRS) of 0-2 and 0-1, respectively) at 90 days. We adjusted for age, gender, baseline National Institutes of Health Stroke Scale, prestroke mRS, clot burden score, intravenous alteplase treatment (IVT) and carotid tandem lesions. Subgroup analyses were performed in patients treated with or without IVT prior to EVT.
Results
In 434 analyzed patients, hyperdense thrombi were not associated with successful reperfusion (aOR 0.99 [95%CI 0.65-1.51]) or favorable functional outcome (aOR 1.28 [95%CI 0.81-2.01]). Hyperdense thrombi were inversely associated with excellent functional outcome (aOR 0.52 [95%CI 0.32-0.85]). This association was stronger in patients treated with IVT prior to EVT (aOR 0.47 [95%CI 0.26-0.85]) than in patients directly treated with EVT (aOR 0.85 [95%CI 0.29-2.52]) (Figure 1).
Conclusions
Hyperdense thrombi were not significantly associated with reperfusion or favorable functional outcome. However, patients with hyperdense thrombi less often achieved excellent functional outcome after EVT.
Trial Registration Number
N/A
RATE OF INTER-HOSPITAL ASPECTS DECAY: ANTICIPATING FAST PROGRESSORS AND OPTIMIZING WORKFLOW
Abstract
Group Name
Not applicable
Background And Aims
Time is relative in large-vessel occlusion acute ischemic stroke (LVO-AIS). We aimed to evaluate the rate of inter-hospital ASPECTS decay (RAD) and its determinants in LVO-AIS patients transferred from a primary (PSC) to a comprehensive stroke center (CSC); and to identify who should undergo a control neuroimage in CSC before endovascular treatment.
Methods
Historical cohort study of consecutive anterior circulation LVO-AIS transferred patients admitted from 1/1/2016 to 31/12/2019 in a CSC. RAD was defined as (ASPECTS PSC – ASPECTS CSC)/hours elapsed between scans. Patients were categorized according to CT repeat/direct to angio-suite pathways and outcome. We compared patients with futile vs useful CT scan revaluation.
Results
We included 601 patients. 245 (40.8%) repeated CT in CSC. Median RAD was 0.4/h (IQR=0.9). Patients excluded from EVT after CT scan repeat (n=64) had a median 1.18/h (0.8) RAD and only 23.6% had good collaterals. Patients that were submitted to EVT after CT scan repeat had a median 0.3/h (0.7) RAD and 81.7% had good collaterals. Collateral score was an independent predictor of RAD (adjusted β = -0.354; 95%CI: -0.194, -0.447, p<0.001). Age (OR:1.04 95% CI 1.02-1.07, p<0.001), NIHSS (OR: 1.11 95%CI 1.06-1.15, p<0.001), ASPECTS score in PSC (OR:0.74 95%CI 0.60-0.91, p=0.006) and collateral score (OR:0.14 95%CI 0.083-0.222, p<0.001) were independent predictors of usefulness in CT scan repeat in CSC.
Conclusions
Inter-hospital rate of ASPECTS decay for each patient can be predicted in PSC and may help to select patients that benefit from repeating CT assessment on arrival to CSC.
Trial Registration Number
Not applicable
THE RELATION BETWEEN ATHEROSCLEROTIC RISK AND CEREBRAL PERFUSION – A CROSS-SECTIONAL STUDY USING ARTERIAL SPIN LABELLING MRI
Abstract
Background And Aims
Non-invasive measurement of cerebral perfusion may be promising for identifying individuals at high risk of cerebrovascular disease for prevention strategies. We tested whether the new and easily calculated arterial spin labelling MRI parameter ‘spatial coefficient of variation’ (sCoV) is a better radiological correlate of atherosclerotic risk than the more conventional white matter hyperintensity volume (WMHV) and cerebral blood flow (CBF).
Methods
195 participants of the preDIVA trial, aged 72-80 years with systolic hypertension (>140 mmHg) were invited for two MRI-scans 2-3 years apart. WMHV were derived from 3D FLAIR and CBF and sCoV from arterial spin labelling MRI. Atherosclerotic risk was operationalized as 10-year cardiovascular risk by the Systematic COronary Risk Evaluation Older People (SCORE-OP). Data were analysed using linear regression.
Results
The mean 10-year cardiovascular risk was 14% at baseline and 34% in the 135 participants at follow-up. CBF was associated with atherosclerotic risk at baseline (standardized-beta=-0.26, 95%CI=-0.40|-0.13, p<0.001) but not follow-up (standardized-beta=-0.14, 95%CI=-0.33|0.04, p=0.12). sCoV was associated with atherosclerotic risk at both time points (baseline standardized-beta=0.23, 95%CI=0.10|0.36, p<0.0001, follow-up standardized-beta=0.20, 95%CI=0.03|0.36, p=0.02). WMHV was not significantly associated with atherosclerotic risk at both time-points (p>0.25). There were no longitudinal associations between change in MRI parameters and atherosclerotic risk. Imputation of missing values, exclusion of outliers, and repeating analyses using the Framingham- and ASCVD risk scores instead of the SCORE-OP gave similar results.
Conclusions
Our findings demonstrate that sCoV correlates better with atherosclerotic risk than the more conventional markers CBF and WMHV. sCoV could be useful to assess cerebrovascular atherosclerotic risk in population analyses.
Trial Registration Number
Not applicable