Automated cerebral infarct volume measurement in follow-up noncontrast CT scans of patients with acute ischemic stroke

Value of Quantitative Collateral Scoring on CT Angiography in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Many studies have emphasized the relevance of collateral flow in patients presenting with acute ischemic stroke. Our aim was to evaluate the relationship of the quantitative collateral score on baseline CTA with the outcome of patients with acute ischemic stroke and test whether the timing of the CTA acquisition influences this relationship.

MATERIALS AND METHODS

From the Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands (MR CLEAN) data base, all baseline thin-slice CTA images of patients with acute ischemic stroke with intracranial large-vessel occlusion were retrospectively collected. The quantitative collateral score was calculated as the ratio of the vascular appearance of both hemispheres and was compared with the visual collateral score. Primary outcomes were 90-day mRS score and follow-up infarct volume. The relation with outcome and the association with treatment effect were estimated. The influence of the CTA acquisition phase on the relation of collateral scores with outcome was determined.

RESULTS

A total of 442 patients were included. The quantitative collateral score strongly correlated with the visual collateral score (ρ = 0.75) and was an independent predictor of mRS (adjusted odds ratio = 0.81; 95% CI, .77-.86) and follow-up infarct volume (exponent β = 0.88; P < .001) per 10% increase. The quantitative collateral score showed areas under the curve of 0.71 and 0.69 for predicting functional independence (mRS 0-2) and follow-up infarct volume of >90 mL, respectively. We found significant interaction of the quantitative collateral score with the endovascular therapy effect in unadjusted analysis on the full ordinal mRS scale (P = .048) and on functional independence (P = .049). Modification of the quantitative collateral score by acquisition phase on outcome was significant (mRS: P = .004; follow-up infarct volume: P < .001) in adjusted analysis.

CONCLUSIONS

Automated quantitative collateral scoring in patients with acute ischemic stroke is a reliable and user-independent measure of the collateral capacity on baseline CTA and has the potential to augment the triage of patients with acute stroke for endovascular therapy.

Association of follow-up infarct volume with functional outcome in acute ischemic stroke: a pooled analysis of seven randomized trials

Background

Follow-up infarct volume (FIV) has been recommended as an early indicator of treatment efficacy in patients with acute ischemic stroke. Questions remain about the optimal imaging approach for FIV measurement.

Objective

To examine the association of FIV with 90-day modified Rankin Scale (mRS) score and investigate its dependency on acquisition time and modality.

Methods

Data of seven trials were pooled. FIV was assessed on follow-up (12 hours to 2 weeks) CT or MRI. Infarct location was defined as laterality and involvement of the Alberta Stroke Program Early CT Score regions. Relative quality and strength of multivariable regression models of the association between FIV and functional outcome were assessed. Dependency of imaging modality and acquisition time (≤48 hours vs >48 hours) was evaluated.

Results

Of 1665 included patients, 83% were imaged with CT. Median FIV was 41 mL (IQR 14–120). A large FIV was associated with worse functional outcome (OR=0.88(95% CI 0.87 to 0.89) per 10 mL) in adjusted analysis. A model including FIV, location, and hemorrhage type best predicted mRS score. FIV of ≥133 mL was highly specific for unfavorable outcome. FIV was equally strongly associated with mRS score for assessment on CT and MRI, even though large differences in volume were present (48 mL (IQR 15–131) vs 22 mL (IQR 8–71), respectively). Associations of both early and late FIV assessments with outcome were similar in strength (ρ=0.60(95% CI 0.56 to 0.64) and ρ=0.55(95% CI 0.50 to 0.60), respectively).

Conclusions

In patients with an acute ischemic stroke due to a proximal intracranial occlusion of the anterior circulation, FIV is a strong independent predictor of functional outcome and can be assessed before 48 hours, oneither CT or MRI.

Collateral status and tissue outcome after intra-arterial therapy for patients with acute ischemic stroke

Intra-arterial therapy (IAT) for ischemic stroke aims to save brain tissue. Collaterals are thought to contribute to prolonged penumbra sustenance. In this study, we investigate the effect of collateral status on brain tissue salvage with IAT. In 500 patients randomized between IAT and standard care, collateral status was graded from 0 (absent) to 3 (good). Final infarct volumes (FIV) were calculated on post-treatment CT. FIVs were compared between treatment groups per collateral grade. Multivariable linear regression with interaction terms was performed to study whether collaterals modified IAT effect on FIV. Four-hundred-forty-nine patients were included in the analysis. Median FIV for the IAT group was significantly lower with 54.5 mL (95% IQR: 21.8-145.0) than for the controls with 81.8 mL (95% IQR: 40.0-154.0) ( p = 0.020). Treatment effect differed across collateral grades, although there was no significant interaction (unadjusted p = 0.054; adjusted p = 0.105). For grade 3, IAT resulted in a FIV reduction of 30.1 mL ( p = 0.024). For grade 2 and 1, this difference was, respectively, 28.4 mL ( p = 0.028) and 28.4 mL ( p = 0.29). For grade 0, this was 88.6 mL ( p = 0.28) in favour of controls. IAT saves substantially more brain tissue as compared to standard care. We observed a trend of increasing effect of IAT with higher collateral grades.

Incorporation of relative cerebral blood flow into CT perfusion maps reduces false ’at risk' penumbra

Purpose

The region defined as ‘at risk’ penumbra by current CT perfusion (CTP) maps is largely overestimated. We aimed to quantitate the portion of true ‘at risk’ tissue within CTP penumbra and to determine the parameter and threshold that would optimally distinguish it from false ‘at risk’ tissue, that is, benign oligaemia.

Methods

Among acute stroke patients evaluated by multimodal CT (NCCT/CTA/CTP) we identified those that had not undergone endovascular/thrombolytic treatment and had follow-up NCCT. Maps of absolute and relative CBF, CBV, MTT, TTP and Tmax as well as summary maps depicting infarcted and penumbral regions were generated using the Intellispace Portal (Philips Healthcare, Best, Netherlands). Follow-up CT was automatically co-registered to the CTP scan and the final infarct region was manually outlined. Perfusion parameters were systematically analysed – the parameter that resulted in the highest true-negative-rate (ie, proportion of benign oligaemia correctly identified) at a fixed, clinically relevant false-negative-rate (ie, proportion of ‘missed’ infarct) of 15%, was chosen as optimal. It was then re-applied to the CTP data to produce corrected perfusion maps.

Results

Forty seven acute stroke patients met selection criteria. Average portion of infarcted tissue within CTP penumbra was 15%±2.2%. Relative CBF at a threshold of 0.65 yielded the highest average true-negative-rate (48%), enabling reduction of the false ‘at risk’ penumbral region by ~half.

Conclusions

Applying a relative CBF threshold on relative MTT-based CTP maps can significantly reduce false ‘at risk’ penumbra. This step may help to avoid unnecessary endovascular interventions.

RETRACTED: Activation of the PI3K-Akt pathway promotes neuroprotection of the δ-opioid receptor agonist against cerebral ischemia-reperfusion injury in rat models

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. The authors contacted the journal to request a retraction: "Recently, we found that some experimental animal samples from another research were mistakenly used in this paper, resulting in the results and conclusions unreliable". Concern was also raised about the reliability of the brain section images in Figure 1, which seem to appear in other publications, as detailed here: https://pubpeer.com/publications/8AF402957928F3F27A1F46B6D556AD; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. In addition, suspected image duplications were detected in Figures 2A, 3B and 4B. The journal requested the corresponding author comment on these concerns and provide the raw data. The author did not fulfil this request and the Editor-in-Chief decided to retract the article.

Value of Thrombus CT Characteristics in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Thrombus CT characteristics might be useful for patient selection for intra-arterial treatment. Our objective was to study the association of thrombus CT characteristics with outcome and treatment effect in patients with acute ischemic stroke.

MATERIALS AND METHODS

We included 199 patients for whom thin-section NCCT and CTA within 30 minutes from each other were available in the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute ischemic stroke in the Netherlands (MR CLEAN) study. We assessed the following thrombus characteristics: location, distance from ICA terminus to thrombus, length, volume, absolute and relative density on NCCT, and perviousness. Associations of thrombus characteristics with outcome were estimated with univariable and multivariable ordinal logistic regression as an OR for a shift toward better outcome on the mRS. Interaction terms were used to investigate treatment-effect modification by thrombus characteristics.

RESULTS

In univariate analysis, only the distance from the ICA terminus to the thrombus, length of >8 mm, and perviousness were associated with functional outcome. Relative thrombus density on CTA was independently associated with functional outcome with an adjusted common OR of 1.21 per 10% (95% CI, 1.02-1.43; P = .029). There was no treatment-effect modification by any of the thrombus CT characteristics.

CONCLUSIONS

In our study on patients with large-vessel occlusion of the anterior circulation, CT thrombus characteristics appear useful for predicting functional outcome. However, in our study cohort, the effect of intra-arterial treatment was independent of the thrombus CT characteristics. Therefore, no arguments were provided to select patients for intra-arterial treatment using thrombus CT characteristics.

Baseline Blood Pressure Effect on the Benefit and Safety of Intra-Arterial Treatment in MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands)

Background and Purpose—

High blood pressure (BP) is associated with poor outcome and the occurrence of symptomatic intracranial hemorrhage in acute ischemic stroke. Whether BP influences the benefit or safety of intra-arterial treatment (IAT) is not known. We aimed to assess the relation of BP with functional outcome, occurrence of symptomatic intracranial hemorrhage and effect of IAT.

Methods—

This is a post hoc analysis of the MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands). BP was measured at baseline, before IAT or stroke unit admission. We estimated the association of baseline BP with the score on the modified Rankin Scale at 90 days and safety parameters with ordinal and logistic regression analysis. Effect of BP on the effect of IAT was tested with multiplicative interaction terms.

Results—

Systolic BP (SBP) had the best correlation with functional outcome. This correlation was U-shaped; both low and high baseline SBP were associated with poor functional outcome. Higher SBP was associated with symptomatic intracranial hemorrhage (adjusted odds ratio, 1.25 for every 10 mm Hg higher SBP [95% confidence interval, 1.09–1.44]). Between SBP and IAT, there was no interaction for functional outcome, symptomatic intracranial hemorrhage, or other safety parameters; the absolute benefit of IAT was evident for the whole SBP range. The same was found for diastolic BP.

Conclusions—

BP does not affect the benefit or safety of IAT in patients with acute ischemic stroke caused by proximal intracranial vessel occlusion. Our data provide no arguments to withhold or delay IAT based on BP.

Clinical Trial Registration—

URL: http://www.isrctn.com . Unique identifier: ISRCTN10888758.

Associations of Ischemic Lesion Volume With Functional Outcome in Patients With Acute Ischemic Stroke

Background and Purpose—

Ischemic lesion volume (ILV) on noncontrast computed tomography at 1 week can be used as a secondary outcome measure in patients with acute ischemic stroke. Twenty-four–hour ILV on noncontrast computed tomography has greater availability and potentially allows earlier estimation of functional outcome. We aimed to assess lesion growth 24 hours after stroke onset and compare the associations of 24-hour and 1-week ILV with functional outcome.

Methods—

We included 228 patients from MR CLEAN trial (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands), who received noncontrast computed tomography at 24-hour and 1-week follow-up on which ILV was measured. Relative and absolute lesion growth was determined. Logistic regression models were constructed either including the 24-hour or including the 1-week ILV. Ordinal and dichotomous (0–2 and 3–6) modified Rankin scale scores were, respectively, used as primary and secondary outcome measures.

Results—

Median ILV was 42 mL (interquartile range, 21–95 mL) and 64 mL (interquartile range: 30–120 mL) at 24 hours and 1 week, respectively. Relative lesion growth exceeding 30% occurred in 121 patients (53%) and absolute lesion growth exceeding 20 mL occurred in 83 patients (36%). Both the 24-hour and 1-week ILVs were similarly significantly associated with functional outcome (both P <0.001). In the logistic analyses, the areas under the curve of the receiver–operator characteristic curves were similar: 0.85 (95% confidence interval, 0.80–0.90) and 0.87 (95% confidence interval, 0.82–0.91) for including the 24-hour and 1-week ILV, respectively.

Conclusions—

Growth of ILV is common 24-hour poststroke onset. Nevertheless, the 24-hour ILV proved to be a valuable secondary outcome measure as it is equally strongly associated with functional outcome as the 1-week ILV.

Clinical Trial Registration—

URL: http://www.isrctn.com . Unique identifier: ISRCTN10888758.

Opercular Index Score: a CT angiography-based predictor of capillary robustness and neurological outcomes in the endovascular management of acute ischemic stroke

BACKGROUND

Many CT angiography (CTA) collateral scoring systems are either subjective or complex and time consuming.

OBJECTIVE

To evaluate the correlation between a CTA collateral scoring system-the Opercular Index Score (OIS)-with neurological outcomes at 90 days following endovascular treatment for acute ischemic stroke (AIS) secondary to large vessel occlusion.

METHODS

Fifty-five patients with AIS due to distal internal carotid artery, M1, or proximal M2 occlusions who underwent endovascular treatment were included. OIS was retrospectively calculated from CTA images, reconstructed from CT perfusion imaging, as the ratio of opacified M3 opercular branches in the Sylvian fissure on the unaffected side to those on the stroke side and dichotomized into favorable (OIS≤2) and poor (OIS>2). The ability of OIS to predict good neurological outcomes (modified Rankin Scale score ≤2 at 90 days) was assessed using sensitivity, specificity, and area under the curve (AUC) with receiver operating characteristic analysis.

RESULTS

Thirty-five patients had a favorable OIS and 20 patients had a poor OIS. Patients with favorable OIS had an 80.0% (n=28) rate of good neurological outcomes compared with 15.0% (n=3) of patients with a poor OIS (p<0.0001). On multivariate logistic regression analysis adjusting for baseline National Institutes of Health Stroke Scale score, OIS, and device used, favorable OIS was the only variable independently associated with good neurological outcome (OR=17.2, 95% CI 3.8 to 104.3) and demonstrated a sensitivity of 90.3% and specificity of 70.8% with an AUC of 0.822.

CONCLUSIONS

OIS is a simple and practical non-invasive scoring system that can be used to predict collateral robustness and good neurological outcome among patients with AIS undergoing endovascular treatment.

Clot Burden Score on Baseline Computerized Tomographic Angiography and Intra-Arterial Treatment Effect in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

A high clot burden score (CBS) is associated with favorable outcome after intravenous treatment for acute ischemic stroke. The added benefit of intra-arterial treatment might be less in these patients. The aim of this exploratory post hoc analysis was to assess the relation of CBS with neurological improvement and endovascular treatment effect.

METHODS

For 499 of 500 patients in the MR CLEAN study (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands), the CBS was determined. Ordinal logistic regression models with and without main baseline prognostic variables were used to assess the association between CBS (continuous or dichotomized at CBS of 6) and a shift toward better outcome on the modified Rankin Scale. The model without main baseline prognostic variables only included treatment allocation and CBS. Models with and without a multiplicative interaction term of CBS and treatment were compared using the χ² test to assess treatment effect modification by CBS.

RESULTS

Higher CBS was associated with a shift toward better outcome on the modified Rankin Scale; adjusted common odds ratio per point CBS was 1.12 (95% confidence interval, 1.04-1.20]. Dichotomized CBS had an adjusted common odds ratio of 1.67 (95% confidence interval, 1.12-2.51). Both effect estimates were slightly attenuated by adding baseline prognostic variables. The addition of the interaction terms did not significantly improve the fit of the models. There was a small and insignificant increase of intra-arterial treatment efficacy in the high CBS group.

CONCLUSIONS

A higher CBS is associated with improved outcome and may be used as a prognostic marker. We found no evidence that CBS modifies the effect of intra-arterial treatment.

CLINICAL TRIAL REGISTRATION

URL: http://www.trialregister.nl. Unique identifier: NTR1804. URL: http://www.controlled-trials.com. Unique identifier: ISRCTN10888758.

Does prior antiplatelet treatment improve functional outcome after intra-arterial treatment for acute ischemic stroke?

Background and purpose

In patients with acute ischemic stroke who receive antiplatelet treatment, uncertainty exists about the effect and safety of intra-arterial treatment. Our aim was to study whether intra-arterial treatment in patients with prior antiplatelet treatment is safe and whether prior antiplatelet treatment modifies treatment effect.

Methods

All 500 MR CLEAN patients were included. We estimated the effect of intra-arterial treatment with ordinal logistic regression analysis, and tested for interaction of antiplatelet treatment with intra-arterial treatment on outcome. Furthermore, safety parameters and serious adverse events were analyzed.

Results

The 144 patients (29%) on antiplatelet treatment were older, more often male, and had more vascular comorbidity. Intra-arterial treatment effect size after adjustments in antiplatelet treatment patients was 1.7 (95% confidence interval 0.9–3.2), and in no antiplatelet treatment patients 1.8 (95% confidence interval: 1.2–2.6). There was no statistically or clinically significant interaction between prior antiplatelet treatment and the relative effect of intra-arterial treatment ( p = 0.78). However, in patients on antiplatelet treatment, the effect of successful reperfusion on functional outcome in the intervention arm of the trial was doubled: the absolute risk difference for favorable outcome after successful reperfusion in patients on prior antiplatelet treatment was 39% versus 18% in patients not on prior antiplatelet treatment (Pinteraction = 0.025). Patients on antiplatelet treatment more frequently had a symptomatic intracranial hemorrhage (15%) compared to patients without antiplatelet treatment (4%), without differences between the control and intervention arm.

Conclusions

Prior treatment with antiplatelet agents did not modify the effect of intra-arterial treatment in patients with acute ischemic stroke presenting with an intracranial large vessel occlusion. There were no safety concerns. In patients with reperfusion, antiplatelet agents may improve functional outcome.

Influence of Device Choice on the Effect of Intra-Arterial Treatment for Acute Ischemic Stroke in MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands)

Background and Purpose—

Intra-arterial treatment by means of retrievable stents has been proven safe and effective. In MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands), the choice of the type of thrombectomy device was left to the discretion of the interventionist. The aim of this study was to explore the differences in functional outcome, neurological recovery, reperfusion, extent of infarction, and adverse events according to stent type and make.

Methods—

The primary outcome was functional outcome at 90 days, assessed with the modified Rankin Scale (mRS). Neuroimaging outcomes included occlusion on computed tomographic angiography at 24 hours, infarct volume at 5 to 7 days, and modified thrombolysis in cerebral infarction scores. Safety outcomes included death within 90 days and any symptomatic intracerebral hemorrhage. We analyzed possible interactions between stent type and treatment with multiple regression models. Treatment effects were adjusted for patient age, stroke severity, and collateral score.

Results—

Of the 500 patients included in the trial, 233 were allocated to intervention. Of these, 124 (53%) were first treated with Trevo (adjusted common odds ratio for shift on the mRS [acOR, 1.98; 95% confidence interval, 1.30–2.92]), 31 (13%) with Solitaire (acOR, 1.90; 95% confidence interval, 0.97–3.73), 40 (17%) with other retrievable stents or mechanical devices (acOR, 0.96; 95% confidence interval, 0.51–3.93], and 38 (16%) could not be treated. There was no interaction between device and treatment effect on functional outcome and all other secondary and safety outcomes.

Conclusions—

We found no evidence for a differential effect of thrombectomy for acute ischemic stroke by type of stent.

Clinical Trial Registration—

URL: http://www.isrctn.com . Unique identifier: ISRCTN10888758.

Assessment of Collateral Status by Dynamic CT Angiography in Acute MCA Stroke: Timing of Acquisition and Relationship with Final Infarct Volume

BACKGROUND AND PURPOSE

Dynamic CTA is a promising technique for visualization of collateral filling in patients with acute ischemic stroke. Our aim was to describe collateral filling with dynamic CTA and assess the relationship with infarct volume at follow-up.

MATERIALS AND METHODS

We selected patients with acute ischemic stroke due to proximal MCA occlusion. Patients underwent NCCT, single-phase CTA, and whole-brain CT perfusion/dynamic CTA within 9 hours after stroke onset. For each patient, a detailed assessment of the extent and velocity of arterial filling was obtained. Poor radiologic outcome was defined as an infarct volume of ≥70 mL. The association between collateral score and follow-up infarct volume was analyzed with Poisson regression.

RESULTS

Sixty-one patients with a mean age of 67 years were included. For all patients combined, the interval that contained the peak of arterial filling in both hemispheres was between 11 and 21 seconds after ICA contrast entry. Poor collateral status as assessed with dynamic CTA was more strongly associated with infarct volume of ≥70 mL (risk ratio, 1.9; 95% CI, 1.3-2.9) than with single-phase CTA (risk ratio, 1.4; 95% CI, 0.8-2.5). Four subgroups (good-versus-poor and fast-versus-slow collaterals) were analyzed separately; the results showed that compared with good and fast collaterals, a similar risk ratio was found for patients with good-but-slow collaterals (risk ratio, 1.3; 95% CI, 0.7-2.4).

CONCLUSIONS

Dynamic CTA provides a more detailed assessment of collaterals than single-phase CTA and has a stronger relationship with infarct volume at follow-up. The extent of collateral flow is more important in determining tissue fate than the velocity of collateral filling. The timing of dynamic CTA acquisition in relation to intravenous contrast administration is critical for the optimal assessment of the extent of collaterals.

Thrombus Permeability Is Associated With Improved Functional Outcome and Recanalization in Patients With Ischemic Stroke

BACKGROUND AND PURPOSE

Preclinical studies showed that thrombi can be permeable and may, therefore, allow for residual blood flow in occluded arteries of patients having acute ischemic stroke. This perviousness may increase tissue oxygenation, improve thrombus dissolution, and augment intra-arterial treatment success. We hypothesize that the combination of computed tomographic angiography and noncontrast computed tomography imaging allows measurement of contrast agent penetrating a permeable thrombus, and it is associated with improved outcome.

METHODS

Thrombus and contralateral artery attenuations in noncontrast computed tomography and computed tomographic angiography images were measured in 184 Multicenter Randomized Clinical trial of Endovascular treatment of acute ischemic stroke in the Netherlands (MR CLEAN) patients with thin-slice images. Two quantitative estimators of the thrombus permeability were introduced: computed tomographic angiography attenuation increase (Δ) and thrombus void fraction (ε). Patients were dichotomized as having a pervious or impervious thrombus and associated with outcome, recanalization, and final infarct volume.

RESULTS

Patients with Δ≥10.9 HU (n=81 [44%]) and ε≥6.5% (n=77 [42%]) were classified as having a pervious thrombus. These patients were 3.2 (95% confidence interval, 1.7-6.4) times more likely to have a favorable outcome, and 2.5 (95% confidence interval, 1.3-4.8) times more likely to recanalyze, for Δ based classification, and similarly for ε. These odds ratios were independent from intravenous or intra-arterial treatment. Final infarct volume was negatively correlated with both perviousness estimates (correlation coefficient, -0.39 for Δ and -0.40 for ε).

CONCLUSIONS

This study shows that simultaneous measurement of thrombus attenuation in noncontrast computed tomography and computed tomographic angiography allows for quantification of thrombus perviousness. Thrombus perviousness is strongly associated with improved functional outcome, smaller final infarct volume, and higher recanalization rate.

Impact of Collateral Status Evaluated by Dynamic Computed Tomographic Angiography on Clinical Outcome in Patients With Ischemic Stroke

Background and Purpose—

Status of collateral circulation is a strong predictor of outcome after acute ischemic stroke. Our aim was to compare the predictive value of strategies for collateral blood flow assessment with dynamic computed tomographic angiography (CTA) and conventional single-phase CT angiography.

Methods—

Patients with a proximal middle cerebral artery occlusion underwent noncontrast CT, single-phase CTA and whole brain CT perfusion/dynamic CTA within 9 hours after stroke onset. We defined poor outcome as a score on the modified Rankin Scale score of ≥3. The association between collateral score and clinical outcome at 3 months was analyzed with Poisson regression. The prognostic value of collateral scoring with dynamic CTA and single-phase CTA in addition to age, stroke severity, and noncontrast CT was assessed with logistic regression and summarized with the area under the curve.

Results—

Seventy patients were included, with a mean age of 68 years. We observed an increased risk of poor outcome in patients with poor collaterals on single-phase CTA (risk ratio, 1.8; 95% confidence interval, 1.0–3.1) and on dynamic CTA (risk ratio, 2.0; 95% confidence interval, 1.5–2.7). The prediction of poor clinical outcome by means of collateral adjustment was better with dynamic CTA (area under the curve, 0.84; likelihood ratio test P <0.01) than by single-phase CTA (area under the curve, 0.80; likelihood ratio test P =0.33).

Conclusions—

Collateral assessment with dynamic CTA better predicts clinical outcome at 3 months than single-phase conventional CTA.

Clinical Trial Registration—

URL: http://www.trialregister.nl/trialreg . Unique identifier: NTR1804. URL: http://www.clinicaltrials.gov . Unique identifier: NCT00880113.

Characteristics of Misclassified CT Perfusion Ischemic Core in Patients with Acute Ischemic Stroke

BACKGROUND

CT perfusion (CTP) is used to estimate the extent of ischemic core and penumbra in patients with acute ischemic stroke. CTP reliability, however, is limited. This study aims to identify regions misclassified as ischemic core on CTP, using infarct on follow-up noncontrast CT. We aim to assess differences in volumetric and perfusion characteristics in these regions compared to areas that ended up as infarct on follow-up.

MATERIALS AND METHODS

This study included 35 patients with >100 mm brain coverage CTP. CTP processing was performed using Philips software (IntelliSpace 7.0). Final infarct was automatically segmented on follow-up noncontrast CT and used as reference. CTP and follow-up noncontrast CT image data were registered. This allowed classification of ischemic lesion agreement (core on CTP: rMTT≥145%, aCBV<2.0 ml/100g and infarct on follow-up noncontrast CT) and misclassified ischemic core (core on CTP, not identified on follow-up noncontrast CT) regions. False discovery ratio (FDR), defined as misclassified ischemic core volume divided by total CTP ischemic core volume, was calculated. Absolute and relative CTP parameters (CBV, CBF, and MTT) were calculated for both misclassified CTP ischemic core and ischemic lesion agreement regions and compared using paired rank-sum tests.

RESULTS

Median total CTP ischemic core volume was 49.7ml (IQR:29.9ml-132ml); median misclassified ischemic core volume was 30.4ml (IQR:20.9ml-77.0ml). Median FDR between patients was 62% (IQR:49%-80%). Median relative mean transit time was 243% (IQR:198%-289%) and 342% (IQR:249%-432%) for misclassified and ischemic lesion agreement regions, respectively. Median absolute cerebral blood volume was 1.59 (IQR:1.43-1.79) ml/100g (P<0.01) and 1.38 (IQR:1.15-1.49) ml/100g (P<0.01) for misclassified ischemic core and ischemic lesion agreement, respectively. All CTP parameter values differed significantly.

CONCLUSION

For all patients a considerable region of the CTP ischemic core is misclassified. CTP parameters significantly differed between ischemic lesion agreement and misclassified CTP ischemic core, suggesting that CTP analysis may benefit from revisions.

Factors associated with recurrent stroke and recanalization in patients presenting with isolated symptomatic carotid occlusion

Background and purpose

Patients with symptomatic internal carotid artery (ICA) occlusion constitute a small proportion of stroke/transient ischaemic attack patients who are at increased risk of early stroke recurrence and poor outcome. The optimal medical treatment for patients with symptomatic ICA occlusion who are ineligible for thrombolysis or thrombectomy is unknown.

Methods

Consecutive patients presenting at a single center with newly diagnosed symptomatic ICA occlusion (not involving the circle of Willis) were retrospectively reviewed. Those treated with intravenous thrombolysis or intra‐arterial thrombolysis/thrombectomy were excluded. Patients were divided into two groups based on whether they experienced recurrent in‐hospital stroke.

Results

The selected study population (n = 33) represented a small (20.4%) proportion of all newly symptomatic carotid occlusions, who nevertheless had an elevated risk of recurrent stroke during admission (24.2%). Of the variables examined (age, gender, admission National Institutes of Health Stroke Scale score, vascular risk factors, atrial fibrillation, prior stroke/transient ischaemic attack and anticoagulation within 48 h of presentation), only anticoagulation was significantly associated with a lower risk of in‐hospital recurrent stroke. Anticoagulated patients showed a decreased incidence of stroke recurrence within the first week (6.7% vs. 38.9%, P = 0.032) and fewer strokes or deaths at 1 month (13.3% vs. 47.1%, P = 0.040). Hemorrhagic transformation was not observed in any patient. On follow‐up imaging, ICA recanalization was significantly more frequent in anticoagulated patients (46.2% vs. 9.1%, P = 0.047).

Conclusion

Patients with newly diagnosed symptomatic ICA occlusion (not involving the circle of Willis) represent a small but high risk subgroup of patients with carotid occlusion. Early anticoagulation was associated with fewer recurrent strokes and increased ICA recanalization. Larger scale prospective studies may be justified.

A randomized trial of intraarterial treatment for acute ischemic stroke

BACKGROUND

In patients with acute ischemic stroke caused by a proximal intracranial arterial occlusion, intraarterial treatment is highly effective for emergency revascularization. However, proof of a beneficial effect on functional outcome is lacking.

METHODS

We randomly assigned eligible patients to either intraarterial treatment plus usual care or usual care alone. Eligible patients had a proximal arterial occlusion in the anterior cerebral circulation that was confirmed on vessel imaging and that could be treated intraarterially within 6 hours after symptom onset. The primary outcome was the modified Rankin scale score at 90 days; this categorical scale measures functional outcome, with scores ranging from 0 (no symptoms) to 6 (death). The treatment effect was estimated with ordinal logistic regression as a common odds ratio, adjusted for prespecified prognostic factors. The adjusted common odds ratio measured the likelihood that intraarterial treatment would lead to lower modified Rankin scores, as compared with usual care alone (shift analysis).

RESULTS

We enrolled 500 patients at 16 medical centers in The Netherlands (233 assigned to intraarterial treatment and 267 to usual care alone). The mean age was 65 years (range, 23 to 96), and 445 patients (89.0%) were treated with intravenous alteplase before randomization. Retrievable stents were used in 190 of the 233 patients (81.5%) assigned to intraarterial treatment. The adjusted common odds ratio was 1.67 (95% confidence interval [CI], 1.21 to 2.30). There was an absolute difference of 13.5 percentage points (95% CI, 5.9 to 21.2) in the rate of functional independence (modified Rankin score, 0 to 2) in favor of the intervention (32.6% vs. 19.1%). There were no significant differences in mortality or the occurrence of symptomatic intracerebral hemorrhage.

CONCLUSIONS

In patients with acute ischemic stroke caused by a proximal intracranial occlusion of the anterior circulation, intraarterial treatment administered within 6 hours after stroke onset was effective and safe. (Funded by the Dutch Heart Foundation and others; MR CLEAN Netherlands Trial Registry number, NTR1804, and Current Controlled Trials number, ISRCTN10888758.).

Imaging Biomarkers for Intra-arterial Stroke Therapy

Despite high rates of early revascularization with intra-arterial stroke therapy, the clinical efficacy of this approach has not been clearly demonstrated. Neuroimaging biomarkers will be useful in future trials for patient selection and for outcomes evaluation. To identify patients who are likely to benefit from intra-arterial therapy, the combination of vessel imaging, infarct size quantification and degree of neurologic deficit appears critical. Perfusion imaging may be useful in specific circumstances, but requires further validation. For measuring treatment outcomes, surrogate biomarkers that appear suitable are angiographic reperfusion as measured by the modified Thrombolysis in Cerebral Infarction scale and final infarct volume.