Ischemic Lesion Location Based on the ASPECT Score for Risk Assessment of Neurogenic Dysphagia

Dysphagia is common in patients with middle cerebral artery (MCA) infarctions and associated with malnutrition, pneumonia, and mortality. Besides bedside screening tools, brain imaging findings may help to timely identify patients with swallowing disorders. We investigated whether the Alberta stroke program early CT score (ASPECTS) allows for the correlation of distinct ischemic lesion patterns with dysphagia. We prospectively examined 113 consecutive patients with acute MCA infarctions. Fiberoptic endoscopic evaluation of swallowing (FEES) was performed within 24 h after admission for validation of dysphagia. Brain imaging (CT or MRI) was rated for ischemic changes according to the ASPECT score. 62 patients (54.9%) had FEES-proven dysphagia. In left hemispheric strokes, the strongest associations between the ASPECTS sectors and dysphagia were found for the lentiform nucleus (odds ratio 0.113 [CI 0.028–0.433; p = 0.001), the insula (0.275 [0.102–0.742]; p = 0.011), and the frontal operculum (0.280 [CI 0.094–0.834]; p = 0.022). A combination of two or even all three of these sectors together increased relative dysphagia frequency up to 100%. For right hemispheric strokes, only non-significant associations were found which were strongest for the insula region. The distribution of early ischemic changes in the MCA territory according to ASPECTS may be used as risk indicator of neurogenic dysphagia in MCA infarction, particularly when the left hemisphere is affected. However, due to the exploratory nature of this research, external validation studies of these findings are warranted in future.

Signal variance-based collateral index in DSC perfusion: A novel method to assess leptomeningeal collateralization in acute ischaemic stroke

As a determinant of the progression rate of the ischaemic process in acute large-vessel stroke, the degree of collateralization is a strong predictor of the clinical outcome after reperfusion therapy and may influence clinical decision-making. Therefore, the assessment of leptomeningeal collateralization is of major importance. The purpose of this study was to develop and evaluate a quantitative and observer-independent method for assessing leptomeningeal collateralization in acute large-vessel stroke based on signal variance characteristics in T2*-weighted dynamic susceptibility contrast (DSC) perfusion-weighted MR imaging (PWI). Voxels representing leptomeningeal collateral vessels were extracted according to the magnitude of signal variance in the PWI raw data time series in 55 patients with proximal large-artery occlusion and an intra-individual collateral vessel index (CVI_PWI) was calculated. CVI_PWI correlated significantly with the initial ischaemic core volume (rho = -0.459, p = 0.0001) and the PWI/DWI mismatch ratio (rho = 0.494, p = 0.0001) as an indicator of the amount of salvageable tissue. Furthermore, CVI_PWI was significantly negatively correlated with NIHSS and mRS at discharge (rho = -0.341, p = 0.015 and rho = -0.305, p = 0.023). In multivariate logistic regression, CVI_PWI was an independent predictor of favourable functional outcome (mRS 0-2) (OR = 16.39, 95% CI 1.42-188.7, p = 0.025). CVI_PWI provides useful rater-independent information on the leptomeningeal collateral supply in acute stroke.

Flat Panel Computed Tomography Pooled Blood Volume and Infarct Prediction in Endovascular Stroke Treatment

Background and Purpose- Patients with large-vessel stroke frequently need to be transferred to comprehensive stroke centers for endovascular treatment. An update of physiological perfusion parameters and stroke progression on arrival is desirable. We examined the reliability of preinterventional pooled blood volume (PBV)-maps acquired by flat-panel detector computed tomography (CT) in the interventional angiography suite. Methods- The volumes of preinterventional perfusion deficit in flat-panel detector CT-PBV source images were compared with final infarct volume on follow-up multislice-CT after endovascular treatment of 29 consecutive patients with occlusion of the middle cerebral artery (MCA) or the distal internal carotid artery (ICA). Results- Endovascular treatment was successful in 26 patients (Thrombolysis in Cerebral Infarction, 2b-3). Overall, the median preinterventional PBV-deficit was 9×larger than median final infarct volume on multislice-CT (86.4 mL [10.3; 111.6] versus 9.6 mL [3.6; 36.8]). This was especially evident in the subgroup of successful recanalization (PBV-deficit: 87.5 mL [10.6; 115.1], final infarct: 8.7 mL [3.6; 29]). In futile recanalization, the final infarct tended to be underestimated (PBV-deficit: 86.4 mL [5.9; -] and final infarct: 116.4 mL [3.5; -]). Conclusions- Flat panel detector CT-PBV is not reliable in predicting the final infarct volume and should not be used in clinical decision making for endovascular treatment of acute cerebral artery occlusions.

The relationship between blood flow impairment and oxygen depletion in acute ischemic stroke imaged with magnetic resonance imaging

Oxygenation-sensitive spin relaxation time T2' and relaxation rate R2' (1/T2') are presumed to be markers of the cerebral oxygen extraction fraction (OEF) in acute ischemic stroke. In this study, we investigate the relationship of T2'/R2' with dynamic susceptibility contrast-based relative cerebral blood flow (rCBF) in acute ischemic stroke to assess their plausibility as surrogate markers of the ischemic penumbra. Twenty-one consecutive patients with internal carotid artery and/or middle cerebral artery occlusion were studied at 3.0 T. A physiological model of the cerebral vasculature (VM) was used to process PWI raw data in addition to a conventional deconvolution technique. T2', R2', and rCBF values were extracted from the ischemic core and hypoperfused areas. Within hypoperfused tissue, no correlation was found between deconvolved rCBF and T2' ( r = -0.05, p = 0.788), or R2' ( r = 0.039, p = 0.836). In contrast, we found a strong positive correlation with T2' ( r = 0.444, p = 0.006) and negative correlation with R2' ( r = -0.494, p = 0.0025) for rCBF_VM, indicating increasing OEF with decreasing CBF and that rCBF based on the vascular model may be more closely related to metabolic disturbances. Further research to refine and validate these techniques may enable their use as MRI-based surrogate markers of the ischemic penumbra for selecting stroke patients for interventional treatment strategies.

Extent of Microstructural Tissue Damage Correlates with Hemodynamic Failure in High-Grade Carotid Occlusive Disease: An MRI Study Using Quantitative T2 and DSC Perfusion

BACKGROUND AND PURPOSE

Chronic hemodynamic impairment in high-grade carotid occlusive disease is thought to cause microstructural abnormalities that might be subclinical or lead to subtle symptoms including cognitive impairment. Quantitative MR imaging allows assessing pathologic structural changes beyond macroscopically visible tissue damage. In this study, high-resolution quantitative T2 mapping combined with DSC-based PWI was used to investigate quantitative T2 changes as a potential marker of microstructural damage in relation to hemodynamic impairment in patients with unilateral high-grade carotid occlusive disease.

MATERIALS AND METHODS

Eighteen patients with unilateral high-grade ICA or MCA stenosis/occlusion were included in the study. T2 values and deconvolved perfusion parameters, including relative CBF, relative CBV, and the relative CBF/relative CBV ratio as a potential indicator of local cerebral perfusion pressure, were determined within areas with delayed TTP and compared with values from contralateral unaffected areas after segmentation of normal-appearing hypoperfused WM and cortical regions. Hemispheric asymmetry indices were calculated for all parameters.

RESULTS

Quantitative T2 was significantly prolonged (P < .01) in hypoperfused tissue and correlated significantly (P < .01) with TTP delay and relative CBF/relative CBV reduction in WM. Significant correlations (P < .001) between TTP delay and the relative CBF/relative CBV ratio were found both in WM and in cortical areas.

CONCLUSIONS

Quantitative T2 can be used as a marker of microstructural tissue damage even in normal-appearing GM and WM within a vascular territory affected by high-grade carotid occlusive disease. Furthermore, the extent of damage correlates with the degree of hemodynamic failure measured by DSC perfusion parameters.

Impact of Lesion Load Thresholds on Alberta Stroke Program Early Computed Tomographic Score in Diffusion-Weighted Imaging

Background and aims

Assessment of ischemic lesions on computed tomography or MRI diffusion-weighted imaging (DWI) using the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is widely used to guide acute stroke treatment. However, it has never been defined how many voxels need to be affected to label a DWI-ASPECTS region ischemic. We aimed to assess the effect of various lesion load thresholds on DWI-ASPECTS and compare this automated analysis with visual rating.

Materials and methods

We analyzed overlap of individual DWI lesions of 315 patients from the previously published predictive value of fluid-attenuated inversion recovery study with a probabilistic ASPECTS template derived from 221 CT images. We applied multiple lesion load thresholds per DWI-ASPECTS region (>0, >1, >10, and >20% in each DWI-ASPECTS region) to compute DWI-ASPECTS for each patient and compared the results to visual reading by an experienced stroke neurologist.

Results

By visual rating, median ASPECTS was 9, 84 patients had a DWI-ASPECTS score ≤7. Mean DWI lesion volume was 22.1 (±35) ml. In contrast, by use of >0, >1-, >10-, and >20%-thresholds, median DWI-ASPECTS was 1, 5, 8, and 10; 97.1% (306), 72.7% (229), 41% (129), and 25.7% (81) had DWI-ASPECTS ≤7, respectively. Overall agreement between automated assessment and visual rating was low for every threshold used (>0%: κ_w = 0.020 1%: κ_w = 0.151; 10%: κ_w = 0.386; 20% κ_w = 0.381). Agreement for dichotomized DWI-ASPECTS ranged from fair to substantial (≤7: >10% κ = 0.48; >20% κ = 0.45; ≤5: >10% κ = 0.528; and >20% κ = 0.695).

Conclusion

Overall agreement between automated and the standard used visual scoring is low regardless of the lesion load threshold used. However, dichotomized scoring achieved more comparable results. Varying lesion load thresholds had a critical impact on patient selection by ASPECTS. Of note, the relatively low lesion volume and lack of patients with large artery occlusion in our cohort may limit generalizability of these findings.

Oxygenation-Sensitive Magnetic Resonance Imaging in Acute Ischemic Stroke Using T2'/R2' Mapping: Influence of Relative Cerebral Blood Volume

BACKGROUND AND PURPOSE

Quantitative T2'/R2' mapping detect locally increased concentrations of deoxygenated hemoglobin-causing a decrease of T2' and increase of R2'-and might reflect increased cerebral oxygen extraction fraction. Because increases of (relative) cerebral blood volume (rCBV) may influence T2' and R2' through accumulation of deoxygenated hemoglobin, we aimed to investigate the impact of rCBV on T2'/R2' in patients with ischemic stroke.

METHODS

Data from patients with acute internal carotid artery and middle cerebral artery occlusion were analyzed. T2', R2', and rCBV were measured within the ischemic core, slightly and severely hypoperfused areas, and their relationship was examined.

RESULTS

A strong negative correlation with rCBV was found for R2' (r=-0.544; P=0.002), and T2' correlated positively with rCBV (r=0.546; P=0.001) in time-to-peak-delayed areas. T2'/R2' within hypoperfused tissue remained unchanged at normal or elevated rCBV levels.

CONCLUSIONS

T2' decrease/R2' increase within hypoperfused areas in ischemic stroke is not caused by local elevations of rCBV but most probably only by increased cerebral oxygen extraction fraction. However, considering rCBV is crucial to assess extent of oxygen extraction fraction changes by means of T2'/R2'.

Microfluidic coagulation assay for monitoring anticoagulant therapy in acute stroke patients

Reliable detection of anticoagulation status in patients treated with non-vitamin K antagonist oral anticoagulants (NOACs) is challenging but of importance especially in the emergency setting. This study evaluated the potential of a whole-blood clotting time assay based on Surface Acoustic Waves (SAW-CT) in stroke-patients. The SAW-technology was used for quick and homogenous recalcification of whole blood inducing a surface-activated clotting reaction quantified and visualised by real-time fluorescence microscopy with automatic imaging processing. In 20 stroke or transient ischaemic attack (TIA)-patients taking NOACs kinetics of SAW-CT were assessed and correlated to other coagulation parameters (PT, aPTT) and NOAC-plasma concentration measured by tandem mass spectrometry (LC-MS/MS). In 225 emergency patients with suspicion of acute stroke or TIA, SAW-CT values were assessed. Mean (± SD) SAW-CT in non-anticoagulated stroke patients (n=180) was 124 s (± 21). In patients on dabigatran or rivaroxaban, SAW-CT values were significantly higher 2 and 8 hours (h) after intake rising up to 267 seconds (s) (dabigatran, 2 h after intake) and 250 s (rivaroxaban, 8 h after intake). In patients on apixaban, SAW-CT values were only moderately increased 2 h after intake (SAW-CT 153 s). In emergency patients, SAW-CT values were significantly higher in NOAC and vitamin K antagonist (VKA)-treated as compared to non-anticoagulated patients. In conclusion, the SAW-CT assay is capable to monitor anticoagulant level and effect in patients receiving dabigatran, rivaroxaban and the VKA phenprocoumon. It has a limited sensitivity for apixaban-detection. If specific SAW-CT results were used as cut-offs, SAW-CT yields high diagnostic accuracy to exclude relevant rivaroxaban and dabigatran concentrations in stroke-patients.

Safety of endovascular treatment in acute stroke patients taking oral anticoagulants

Background

The endovascular treatment of acute cerebral ischemia has been proven beneficial without major safety concerns. To date, the role of endovascular treatment in patients treated with oral anticoagulants, which may be associated with periprocedural intracranial bleeding, remains uncertain.

Aims

The objective of the current analysis is to evaluate the safety of endovascular treatment in patients treated with oral anticoagulants.

Methods

The ENDOSTROKE-Registry is a commercially independent, prospective observational study in 12 stroke centers in Germany and Austria collecting pre-specified variables about endovascular stroke therapy.

Results

Data from 815 patients (median age 70 (interquartile range (IQR) 20), 57% male) undergoing endovascular treatment with known anticoagulation status were analyzed. A total of 85 (median age 76 (IQR 8), 52% male) patients (10.4%) took vitamin-K-antagonists prior to endovascular treatment. Anticoagulation status as measured with international normalized ratio was above 2.0 in 31 patients. Intracranial hemorrhage occurred in 11.8% of patients taking vitamin-K-antagonists compared to no-vitamin-K-antagonists (12.2%, p = 0.909). After adjustment for confounding factors which were unbalanced at univariate level such as NIHSS and age, anticoagulation status was not found to significantly influence clinical outcome (modified Rankin Scale 3–6) and occurrence of intracranial hemorrhage in a multivariate logistic regression analysis.

Conclusion

Prior use of vitamin-K-antagonists was not associated with a higher rate of periprocedural intracranial hemorrhage after endovascular treatment or worse outcome. Endovascular treatment should be considered as an important treatment option in patients taking vitamin-K-antagonists.

T2-Imaging to Assess Cerebral Oxygen Extraction Fraction in Carotid Occlusive Disease: Influence of Cerebral Autoregulation and Cerebral Blood Volume

PURPOSE

Quantitative T2'-mapping detects regional changes of the relation of oxygenated and deoxygenated hemoglobin (Hb) by using their different magnetic properties in gradient echo imaging and might therefore be a surrogate marker of increased oxygen extraction fraction (OEF) in cerebral hypoperfusion. Since elevations of cerebral blood volume (CBV) with consecutive accumulation of Hb might also increase the fraction of deoxygenated Hb and, through this, decrease the T2'-values in these patients we evaluated the relationship between T2'-values and CBV in patients with unilateral high-grade large-artery stenosis.

MATERIALS AND METHODS

Data from 16 patients (13 male, 3 female; mean age 53 years) with unilateral symptomatic or asymptomatic high-grade internal carotid artery (ICA) or middle cerebral artery (MCA) stenosis/occlusion were analyzed. MRI included perfusion-weighted imaging and high-resolution T2'-mapping. Representative relative (r)CBV-values were analyzed in areas of decreased T2' with different degrees of perfusion delay and compared to corresponding contralateral areas.

RESULTS

No significant elevations in cerebral rCBV were detected within areas with significantly decreased T2'-values. In contrast, rCBV was significantly decreased (p<0.05) in regions with severe perfusion delay and decreased T2'. Furthermore, no significant correlation between T2'- and rCBV-values was found.

CONCLUSIONS

rCBV is not significantly increased in areas of decreased T2' and in areas of restricted perfusion in patients with unilateral high-grade stenosis. Therefore, T2' should only be influenced by changes of oxygen metabolism, regarding our patient collective especially by an increase of the OEF. T2'-mapping is suitable to detect altered oxygen consumption in chronic cerebrovascular disease.

Estimating the Quantitative Demand of NOAC Antidote Doses on Stroke Units

BACKGROUND

The first specific antidote for non-vitamin K antagonist oral anticoagulants (NOAC) has recently been approved. NOAC antidotes will allow specific treatment for 2 hitherto problematic patient groups: patients with oral anticoagulant therapy (OAT)-associated intracerebral hemorrhage (ICH) and maybe also thrombolysis candidates presenting on oral anticoagulation (OAT). We aimed to estimate the frequency of these events and hence the quantitative demand of antidote doses on a stroke unit.

METHODS

We extracted data of patients with acute ischemic stroke and ICH (<24 h after symptom onset) in the years 2012-2015 from a state-wide prospective stroke inpatient registry. We selected 8 stroke units and determined the mode of OAT upon admission in 2012-2013. In 2015, the mode of OAT became a mandatory item of the inpatient registry. From the number of anticoagulated patients and the NOAC share, we estimated the current and future demand for NOAC antidote doses on stroke units.

RESULTS

Eighteen percent of ICH patients within 6 h of symptom onset or an unknown symptom onset were on OAT. Given a NOAC share at admission of 40%, about 7% of all ICH patients may qualify for NOAC reversal therapy. Thirteen percent of ischemic stroke patients admitted within 4 h presented on anticoagulation. Given the availability of an appropriate antidote, a NOAC share of 50% could lead to a 6.1% increase in thrombolysis rate.

CONCLUSIONS

Stroke units serving populations with a comparable demographic structure should prepare to treat up to 1% of all acute ischemic stroke patients and 7% of all acute ICH patients with NOAC antidotes. These numbers may increase with the mounting prevalence of atrial fibrillation and an increasing use of NOAC.

Abstract TP9: Safety of Endovascular Treatment in Acute Stroke Patients Taking Oral Anticoagulants

Introduction: The endovascular treatment (EVT) of cerebral ischemia in the case of large vessel occlusion has been established over recent years. Randomized trials showed a positive impact on the clinical outcome of endovascular treatment in addition to thrombolysis with respect to clinical outcome and safety, so that this therapeutic option will be implemented in future guidelines. The role of EVT in patients treated with oral anticoagulants remains uncertain.

Hypothesis: We assessed the hypothesis that application of EVT is safe with regard to the occurrence of intracranial bleeding and clinical outcome in patients taking anticoagulants.

Methods: The ENDOSTROKE-Registry is a commercially independent, prospective observational study in 12 stroke centers in Germany and Austria launched in January 2011. An online tool served for data acquisition of pre-specified variables concerning endovascular stroke therapy.

Results: Data from 815 patients (median age 70, 57% male) undergoing EVT and known anticoagulation status were analyzed. A total of 85 (median age 76, 52% male) patients (10.4%) took oral anticoagulants prior to EVT. Anticoagulation status as measured with INR was 2.0-3.0 in 24 patients (29%), <2.0 in 52 patients (63%) and above 3.0 in 7 patients (8%) of 83 patients with valid INR data prior to EVT. Patients taking anticoagulants were significantly older (median age 76 vs. 69, p < 0.001). Comparing those patients taking anticoagulants and those not, there were no differences concerning NIHSS at admission (with anticoagulants Median-NIHSS 17 vs. without Median-NIHSS 15, p = 0.492, Mann Whitney Test) and the rate of intracranial hemorrhage after intervention (with anticoagulants 11.8% vs. without 12.2%, p = 0.538). After adjustment for age and NIHSS at admission there were no significant differences between the two groups with regard to good clinical outcome, as measured with the modified ranking scale (mRS, 90d-mRS 0-2, 39.2% of patients not receiving anticoagulants; 25.9% of those receiving anticoagulants).

Conclusion: The application of endovascular treatment in patients taking oral anticoagulants is safe and should be considered in acute stroke treatment as an important alternative to contraindicated intravenous thrombolysis.

Ischemic core and hypoperfusion volumes predict infarct size in SWIFT PRIME

OBJECTIVE

Within the context of a prospective randomized trial (SWIFT PRIME), we assessed whether early imaging of stroke patients, primarily with computed tomography (CT) perfusion, can estimate the size of the irreversibly injured ischemic core and the volume of critically hypoperfused tissue. We also evaluated the accuracy of ischemic core and hypoperfusion volumes for predicting infarct volume in patients with the target mismatch profile.

METHODS

Baseline ischemic core and hypoperfusion volumes were assessed prior to randomized treatment with intravenous (IV) tissue plasminogen activator (tPA) alone versus IV tPA + endovascular therapy (Solitaire stent-retriever) using RAPID automated postprocessing software. Reperfusion was assessed with angiographic Thrombolysis in Cerebral Infarction scores at the end of the procedure (endovascular group) and Tmax > 6-second volumes at 27 hours (both groups). Infarct volume was assessed at 27 hours on noncontrast CT or magnetic resonance imaging (MRI).

RESULTS

A total of 151 patients with baseline imaging with CT perfusion (79%) or multimodal MRI (21%) were included. The median baseline ischemic core volume was 6 ml (interquartile range= 0-16). Ischemic core volumes correlated with 27-hour infarct volumes in patients who achieved reperfusion (r = 0.58, p < 0.0001). In patients who did not reperfuse (<10% reperfusion), baseline Tmax > 6-second lesion volumes correlated with 27-hour infarct volume (r = 0.78, p = 0.005). In target mismatch patients, the union of baseline core and early follow-up Tmax > 6-second volume (ie, predicted infarct volume) correlated with the 27-hour infarct volume (r = 0.73, p < 0.0001); the median absolute difference between the observed and predicted volume was 13 ml.

INTERPRETATION

Ischemic core and hypoperfusion volumes, obtained primarily from CT perfusion scans, predict 27-hour infarct volume in acute stroke patients who were treated with reperfusion therapies.

Stent-retriever thrombectomy after intravenous t-PA vs. t-PA alone in stroke

BACKGROUND

Among patients with acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation, less than 40% regain functional independence when treated with intravenous tissue plasminogen activator (t-PA) alone. Thrombectomy with the use of a stent retriever, in addition to intravenous t-PA, increases reperfusion rates and may improve long-term functional outcome.

METHODS

We randomly assigned eligible patients with stroke who were receiving or had received intravenous t-PA to continue with t-PA alone (control group) or to undergo endovascular thrombectomy with the use of a stent retriever within 6 hours after symptom onset (intervention group). Patients had confirmed occlusions in the proximal anterior intracranial circulation and an absence of large ischemic-core lesions. The primary outcome was the severity of global disability at 90 days, as assessed by means of the modified Rankin scale (with scores ranging from 0 [no symptoms] to 6 [death]).

RESULTS

The study was stopped early because of efficacy. At 39 centers, 196 patients underwent randomization (98 patients in each group). In the intervention group, the median time from qualifying imaging to groin puncture was 57 minutes, and the rate of substantial reperfusion at the end of the procedure was 88%. Thrombectomy with the stent retriever plus intravenous t-PA reduced disability at 90 days over the entire range of scores on the modified Rankin scale (P<0.001). The rate of functional independence (modified Rankin scale score, 0 to 2) was higher in the intervention group than in the control group (60% vs. 35%, P<0.001). There were no significant between-group differences in 90-day mortality (9% vs. 12%, P=0.50) or symptomatic intracranial hemorrhage (0% vs. 3%, P=0.12).

CONCLUSIONS

In patients receiving intravenous t-PA for acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation, thrombectomy with a stent retriever within 6 hours after onset improved functional outcomes at 90 days. (Funded by Covidien; SWIFT PRIME ClinicalTrials.gov number, NCT01657461.).

Abstract W MP1: Collateral Grade Drives the Importance of Time to Reperfusion in the Stentriever Era: The ENDOSTROKE Registry

Background: Time to angiographic reperfusion has been hailed as paramount to all other factors in achieving good clinical outcomes after endovascular stroke therapy (EVT). Heterogeneity in collateral status, however, may dictate the individual timecourse of therapeutic risk/benefit in a given patient. Time to earliest reperfusion (Thrombolysis in Cerebral Ischemia 2A or TICI2A) has not been previously analyzed and this measure may considerably decrease with recent use of modern stentriever devices.

Methods: ENDOSTROKE is an industry-independent, centrally-monitored multicenter registry evaluating EVT in routine clinical practice. Central reading of angiographic data blinded to clinical information was performed by the core lab. For these analyses, we selected only proximal MCA occlusions proven as TICI 0 before EVT, with available ASITN collateral grade and final TICI 2B-3. The data center analyzed the relationship of these angiographic parameters with clinical variables, including 90-day mRS 0-2 (good clinical outcome).

Results: 116 patients met these strict inclusion criteria. Median age was 72 years (63, 76) with median initial NIHSS 15 (12, 19). 80 had good collaterals (ASTIN grades 3-4), 36 patients had poor collaterals (ASITN grades 0-2). Both groups did not differ significantly concerning age or initial NIHSS. Good clinical outcome was reached by 51% with good and 42% with poor collaterals (p=0.339). Time from symptom onset to the start of angiography was similar in both groups (200 min vs. 186 min in good vs. poor collaterals, p=0.393). However, in the poor collaterals group, time to TICI 2A was significantly shorter in patients with good clinical outcome (177 min (151, 221)) than in patients with poor clinical outcome (261 min (184, 326), p=0.012). In patients with good collaterals, no significant difference of the time to TICI 2A was found between good (229 min (152, 281)) and poor outcome (230 min (178, 298), p=0.779).

Conclusions: Time to angiographic reperfusion, from symptom onset to earliest reperfusion (TICI 2A) dominates endovascular procedure time. Time is paramount in those with poor collaterals, whereas time may be irrelevant in those with good collaterals.

Abstract 105: Time for Collaterals? Evidence from 695 Endovascular Therapy Cases for Acute Stroke in ENDOSTROKE

Background: Recent stroke clinical trials demonstrate the profound impact of collaterals, yet time constraints are often cited as rationale for not evaluating or imaging collaterals prior to endovascular therapy (EVT). We examined the role of collaterals on patient outcomes in a large registry of EVT, analyzing actual time required to obtain such data before treatment of various occlusion sites and monitoring for potential harm.

Methods: ENDOSTROKE is an industry-independent, centrally-monitored multicenter registry evaluating EVT in routine clinical practice. Central reading of angiographic data blinded to clinical information was performed by the core lab in 695 patients assessing TICI scores, ASITN collateral grade and detailed procedural time metrics.

Results: 75% had anterior circulation strokes (including 270 proximal MCA, 106 ICAT, 90 cICA occlusions) and 25% posterior circulation strokes (including 148 basilar artery occlusions). Assessment of ASITN collateral grade was possible in 511 (73%) of patients; in 184 (27%) collateral status was not obtained prior to therapeutic intervention. Median time from initial angiography and first evidence of TICI 2A reperfusion was only one minute longer in patients with available ASITN scores than in those without (38 min (23, 61) vs. 37 (22, 55), p=0.552) and time-differences were even smaller in anterior circulation strokes (median time 37 min in both groups). In vertebrobasilar occlusion, this time metric was 5 minutes longer in those with available ASITN scores (39 min (24, 39)) than in those without (34 min (23, 52), p=0.357). Of those with ASITN available, patients with grade 3-4 had much better outcomes (48% 0-2 90-day mRS) than patients with grade 0-2 (30%, p<0.0001). No excess in complication rate (i.e. dissection, thrombemboli) was noted in the cohort with available ASITN.

Conclusions: Collaterals have a dramatic association with clinical outcomes in the largest endovascular study to date. In routine practice, EVT outcomes across various occlusion sites are strongly influenced by collateral grade. Negligible time of only a few minutes is typically required to obtain such essential data prior to treatment with no cost of incremental harm.

Collateral vessels in proximal middle cerebral artery occlusion: the ENDOSTROKE study

PURPOSE

To determine the impact of collateral vessel status on clinical and imaging outcomes in patients undergoing endovascular therapy (EVT) for proximal middle cerebral artery (MCA) occlusion.

MATERIALS AND METHODS

There were 160 patients with proximal MCA occlusion at six centers in this institutional review board-approved multicenter EVT registry. Angiograms were analyzed at a blinded core laboratory, and collateral vessel status was assessed by using the American Society of Interventional and Therapeutic Neuroradiology (ASITN)/Society of Interventional Radiology (SIR) collateral vessel grading system, while reperfusion was assessed by using the Thrombolysis in Cerebral Infarction (TICI) scale. Good outcome was defined as a modified Rankin Scale score of 0-2 at follow-up. Binary logistic regression analysis was performed by using parameters with P < .2 in univariate analysis.

RESULTS

Good clinical outcome was attained in 62 (39%) of the 160 patients, and TICI 2b-3 reperfusion was achieved in 94 (59%) patients. Nineteen patients had ASITN/SIR collateral vessel grades of 0 or 1, 63 patients had a grade of 2, and 78 patients had grades of 3 or 4. Better collateral vessels were associated with higher reperfusion rates (21%, 48%, and 77% for ASITN/SIR grades of 0 or 1, 2, and 3 or 4, respectively; P < .001), a higher proportion of infarcts smaller than one-third of the MCA territory (32%, 48%, and 69% for ASITN/SIR grades of 0 or 1, 2, and 3 or 4, respectively; P < .001), and a higher proportion of good clinical outcome (11%, 35%, and 49% for ASITN/SIR grades of 0 or 1, 2, and 3 or 4, respectively; P = .007). At multivariable analysis, collateral vessel status independently predicted reperfusion, final infarct size, and clinical outcome. Within an onset-to-treatment time (OTT) of 0-3 hours, collateral vessel status predicted final infarct size and reperfusion. Within an OTT of 3-6 hours, it additionally predicted clinical outcome, with 53% of patients with ASITN/SIR grades of 3 or 4 having a good outcome, as compared with 0% of patients with grades of 0 or 1 and 27% of patients with a grade of 2 (P = .008).

CONCLUSION

In this patient population, collateral vessel status independently predicted the pivotal outcome parameters of reperfusion, infarct size, and clinical outcome. These data underscore the utility of patient selection for EVT on the basis of collateral vessel status.

Changes of pH and energy state in subacute human ischemia assessed by multinuclear magnetic resonance spectroscopy

BACKGROUND AND PURPOSE

In vivo changes in tissue pH and energy metabolism are key to understanding stroke pathophysiology. Our goal was to study pH changes in subacute ischemic stroke and their relation to energy metabolism, which, unlike acidosis in acute stroke, are not yet well understood.

METHODS

We measured tissue pH and phospholipid as well as cell energy markers, including creatine, phosphocreatine, and N-acetyl-aspartate in subacute stroke with combined (1)H and (31)P magnetic resonance spectroscopy. We included 19 patients with first-ever ischemic stroke (mean time after stroke, 6 days). We then compared metabolite concentrations in the ischemic tissue to contralateral (healthy) tissue using multivariate ANOVA to assess significant differences in metabolite levels between both tissue compartments.

RESULTS

In subacute stroke, a tissue fraction with significantly increased tissue pH was observed as compared with healthy contralateral tissue (pH, 7.09 versus 7.03; P=0.002) concurrent with splitting of the pH signal with 1 peak being more alkalotic. Furthermore, only a moderate decrease of energy-rich metabolites (phosphocreatine reduced by 17%, ATP reduced by 19%) was present, whereas total creatine was reduced by 51%.

CONCLUSIONS

The finding of an alkalotic pH split in subacute ischemia is unprecedented. The pH split and only incomplete energy loss in subacute stroke suggest 2 differently viable cellular moieties, best explained by active compensatory mechanisms after acute cerebral ischemia.

Frequency, risk of hemorrhage and treatment considerations for cerebral arteriovenous malformations with associated aneurysms

BACKGROUND

Data on arteriovenous malformations (AVMs) of the brain with AVM-associated aneurysms (AAA) are scarce. This study addresses the incidence, rate of hemorrhage, treatment strategies and stability during follow-up in a neurovascular center.

METHODS

We retrospectively reviewed patients harboring an AVM with at least one AAA treated at our neurovascular center between 2002 and 2013.

RESULTS

Of 216 patients, 59 (27.3%) had at least one AAA (n = 92 aneurysms total). Compared to patients without AAA, hemorrhagic presentation occurred more frequently (61.0% versus 43.9%, p = 0.025), and the rate of infratentorial AVMs was higher (37.3% versus 16.6%, p = 0.001). The aneurysm was the origin of the bleeding in most cases, most often categorized as a feeding artery aneurysm. Overall, the first and recurrent hemorrhage were associated with a high mortality and morbidity (15.3% and 39%, respectively). Aneurysms were treated by coiling (n = 21), surgery (n = 18), or embolizaton with liquid embolization agents (n = 11). All aneurysms treated by embolization and surgery remained occluded during follow-up (mean follow-up 39.0 ± 45.0 months). However, in incomplete AVM obliteration, significant recurrence of the treated aneurysm was noted after endovascular coiling (37.5%), which may be related to the persistence of pathological blood flow.

CONCLUSION

In our series, AAA was a significant risk factor for hemorrhage and was associated with a poor outcome. It seems worthwhile to consider whether the aneurysm itself is a risk factor or only an epiphenomenon of severely altered hemodynamics induced by these special AVMs and therefore only the most common site of rupture. As the complication rate was low for aneurysm occlusion, we recommend treating these aneurysms whenever possible. Furthermore, obliteration of the AVM should be strived for as this subtype may be associated with an increased risk of hemorrhage.

Validity of acute stroke lesion volume estimation by diffusion-weighted imaging-Alberta Stroke Program Early Computed Tomographic Score depends on lesion location in 496 patients with middle cerebral artery stroke

BACKGROUND AND PURPOSE

Alberta Stroke Program Early Computed Tomographic Score (ASPECTS) has been used to estimate diffusion-weighted imaging (DWI) lesion volume in acute stroke. We aimed to assess correlations of DWI-ASPECTS with lesion volume in different middle cerebral artery (MCA) subregions and reproduce existing ASPECTS thresholds of a malignant profile defined by lesion volume ≥100 mL.

METHODS

We analyzed data of patients with MCA stroke from a prospective observational study of DWI and fluid-attenuated inversion recovery in acute stroke. DWI-ASPECTS and lesion volume were calculated. The population was divided into subgroups based on lesion localization (superficial MCA territory, deep MCA territory, or both). Correlation of ASPECTS and infarct volume was calculated, and receiver-operating characteristics curve analysis was performed to identify the optimal ASPECTS threshold for ≥100-mL lesion volume.

RESULTS

A total of 496 patients were included. There was a significant negative correlation between ASPECTS and DWI lesion volume (r=-0.78; P<0.0001). With regards to lesion localization, correlation was weaker in deep MCA region (r=-0.19; P=0.038) when compared with superficial (r=-0.72; P<0.001) or combined superficial and deep MCA lesions (r=-0.72; P<0.001). Receiver-operating characteristics analysis revealed ASPECTS≤6 as best cutoff to identify ≥100-mL DWI lesion volume; however, positive predictive value was low (0.35).

CONCLUSIONS

ASPECTS has limitations when lesion location is not considered. Identification of patients with malignant profile by DWI-ASPECTS may be unreliable. ASPECTS may be a useful tool for the evaluation of noncontrast computed tomography. However, if MRI is used, ASPECTS seems dispensable because lesion volume can easily be quantified on DWI maps.

Quantitative T2'-mapping in acute ischemic stroke

BACKGROUND AND PURPOSE

Quantitative T2'-mapping detects regional changes in the relation of oxygenated and deoxygenated haemoglobine and might reflect areas with increased oxygen extraction. T2'-mapping in conjunction with an elaborate algorithm for motion correction was performed in patients with acute large-vessel stroke, and quantitative T2'-values were determined within the diffusion-weighted imaging lesion and perfusion-restricted tissue.

METHODS

Eleven patients (median age, 71 years) with acute middle cerebral or internal carotid artery occlusion underwent MRI before scheduled endovascular treatment. MR-examination included diffusion- and perfusion-weighted imaging and quantitative, motion-corrected mapping of T2'. Time-to-peak maps were thresholded for different degrees of perfusion delays (eg, ≥0 s, ≥ 2s) when compared with a reference time-to-peak value from healthy contralateral tissue. Mean T2'-values in areas with reduced apparent diffusion coefficient and in areas with impaired perfusion were compared with T2'-values in corresponding contralateral areas.

RESULTS

Median time between symptom onset and MRI was 238 minutes. T2'-values were significantly reduced within the apparent diffusion coefficient -lesion when compared with contralateral healthy tissue (83 ms [67, 97] versus 97 ms [91, 111]; P<0.003). In perfusion-restricted tissue, T2'-values were also significantly lower when compared with contralateral healthy tissue (ie, for time to peak, ≥0 s 93 ms [86, 102] versus 104 [90, 110]; P=0.008) but were significantly higher than within the apparent diffusion coefficient lesion. The severity of the perfusion impairment had no influence on median T2'-values.

CONCLUSIONS

Motion-corrected T2'-mapping reveals significant and gradually declining values from healthy to perfusion-disturbed to apparent diffusion coefficient-restricted tissue. Current T2'-mapping can differentiate between the ischemic core and the perfusion-impaired areas but not on its own between penumbral and oligemic tissue.

Abstract W MP60: Atrial Fibrillation is Associated with Worse Collaterals in Acute Stroke: Angiography in the ENDOSTROKE Registry

Background: Risk factors for stroke may alter hemodynamics or invoke ischemic preconditioning, yet the impact of such factors on response to acute stroke treatment and the potential relationship with collateral circulation remains unknown.

Methods: Consecutive cases enrolled in the International Multicenter Registry for Mechanical Recanalization Procedures in Acute Stroke (ENDOSTROKE) were analyzed with respect to collateral status on baseline angiography before endovascular therapy. ASITN/SIR collateral grade (0-1/2/3-4) was scored by the core lab, blind to all other data. Collateral grade was analyzed with respect to numerous baseline risk factors, demographics and outcomes after endovascular intervention.

Results: 109 patients (median age 69 years (25 th , 75 th percentiles: 56, 77); 51% women; median baseline NIHSS 15 (13, 18)) with complete (TICI 0) anterior circulation occlusions (M1, n=71; ICA, n=28; M2, n=10) at baseline were evaluated based on collateral grade (0-1, n=12; 2, n=41; 3-4, n=56). Worse collaterals were noted in patients with atrial fibrillation (ASITN grades 0-1/2/3-4: 21%/30%/49%) as compared to patients without atrial fibrillation (5%/42%/53%, p=0.024), yet cardioembolic stroke etiology was unrelated. Other baseline features such as age, gender, time to presentation, other co-morbidities and labs were unrelated to collateral grade. Post-procedure reperfusion (TICI 2b-3) was significantly associated with better collaterals (OR 2.58 (1.343-4.957, p=0.004). Similarly, final infarct size was significantly smaller in those with better collaterals. Good clinical outcomes (mRS 0-2 at day 90) were less frequent in those with poorer collaterals (OR 0.403 (0.199-0.813, p=0.011).

Conclusions: Atrial fibrillation, but not cardioembolic stroke etiology, is associated with worse collaterals. Hemodynamic implications, such as diminished cardiac output due to atrial fibrillation, may result in less favorable outcomes after endovascular therapy for acute stroke.

Abstract T MP27: Outcome Predictors in Basilar- versus Proximal Middle Cerebral Artery Occlusion: Data from the Endostroke-Registry

Background and Purpose: Large vessel stroke is frequently associated with poor long-term clinical outcome despite multimodal treatment approaches. Here we compare outcome predictors in angiographic proven proximal Middle Cerebral Artery (MCA)- versus Basilar Artery (BA) occlusion undergoing endovascular stroke treatment (EVT).

Methods: ENDOSTROKE is an investigator-initiated, industrially-independent multicenter, multinational registry for consecutive patients undergoing EVT for large vessel stroke. This analysis focuses on patients with angiographically proven M1-MCA (n=352) or BA-occlusion (n=121). Recanalization was defined as Thrombolysis in Cerebral Ischemia (TICI) scores 2b-3, good outcome as a Modified Rankin Scale (MRS) score of 0-2 assessed after 3 months.

Results: 77% of MCA- and 77% of BA-occlusions reached TICI 2b-3 recanalization, but good clinical outcome was achieved in only 31% vs. 40% of BA- vs. MCA-occlusions (n.s., Mann-Whitney-Test). Median age was 67 years (25 th and 75 th percentile: 59, 77) in BA-occlusion and 70 (58, 77) in MCA-occlusion (n.s.). Admission-NIHSS was significantly higher in BA-occlusion (22 (10, 29)) than in MCA-occlusion (15 (12, 19), p<0.001). Serum glucose and thromboycte count were not significantly different between MCA- and BA-occlusions. In MCA-occlusion, independent factors significantly associated with good clinical outcome were lower age, lower initial NIHSS, lower glucose as well as TICI 2b-3 recanalization. In BA-occlusion, only lower initial NIHSS was significantly associated with good clinical outcome (univariate and multivariate analysis). Time to recanalization was not significantly related to outcome in MCA- or BA-occlusions.

Conclusions: While initial stroke severity is a potent prognostic factor in both, MCA- and BA-occlusion, other classical outcome predictors, especially patients′ age do not seem to be of as high importance in BA-occlusion as in MCA-occlusion. Presumably, those predictors are offset by the exact site of BA-occlusion (i.e. mid-basilar vs. top of the basilar) leading to differences in initial stroke severity and potentially early irreversible tissue damage to pivotal brain stem structures.

Directional diffusion of corticospinal tract supports therapy decisions in idiopathic normal-pressure hydrocephalus

INTRODUCTION

Gait disturbance in patients with idiopathic normal pressure hydrocephalus (iNPH) may be caused by alterations of the corticospinal tract that we aimed to measure with diffusion tensor imaging (DTI). The directional diffusion parameters axial diffusivity and fractional anisotropy (FA) reflect axon integrity, whereas mean diffusivity, radial diffusivity and magnetization transfer ratio (MTR) reflect myelin content.

METHODS

Twenty-six patients with probable iNPH were grouped into drainage responders (n = 12) and drainage non-responders (n = 14) according to their improvement on gait assessment tests after a 3-day lumbar CSF drainage. We measured DTI and MTR of the corticospinal tract and, as reference, of the superior longitudinal fascicle before and after CSF withdrawal in iNPH and in ten age-matched controls. Drainage responders were re-examined after ventricoperitoneal shunting. Differences before any intervention and changes upon CSF withdrawal were evaluated.

RESULTS

Axial diffusivity in corticospinal tract and superior longitudinal fascicle was higher in both patient groups compared to controls (p < 0.001). Only in the corticospinal tract of drainage responders was FA higher compared to controls, and both FA and axial diffusivity decreased after shunting. For axial diffusivity upon CSF drainage, a decrease of >0.7 % discriminated drainage responders from drainage non-responders with 82 % sensitivity, and a decrease of >1 % predicted overall improvement after shunting with 87.5 % sensitivity and 75 % specificity. The specificity to discriminate responders/non-responders was low for all DTI values (max. 69 % for FA values).

CONCLUSION

High values of directional diffusion parameters in the corticospinal tract are found in iNPH patients indicating affection of its axons. Increased values and their decrease upon CSF drainage may facilitate treatment decisions in clinically uncertain cases.

Combining magnetic resonance imaging within six-hours of symptom onset with clinical follow-up at 24 h improves prediction of 'malignant' middle cerebral artery infarction

BACKGROUND

A large diffusion-weighted imaging lesion ≤six-hours of symptom onset was found to predict the development of 'malignant' middle cerebral artery infarction with high specificity, positive predictive value, and negative predictive value, but sensitivity was low.

HYPOTHESIS

We tested the hypothesis that sensitivity can be improved by adding information from clinical follow-up examination after 24 h.

METHODS

We analyzed data from a prospective, multicenter, observational cohort study of patients with acute ischemic stroke and middle cerebral artery occlusion studied by stroke magnetic resonance imaging ≤six-hours of symptom onset. We used the National Institutes of Health Stroke Scale to assess severity of symptoms after 24 h. We used the Classification and Regression Trees analysis to define the optimal thresholds of diffusion-weighted imaging lesion volume and the National Institutes of Health Stroke Scale after 24 h in patients developing 'malignant' middle cerebral artery infarction. We calculated sensitivity, specificity, positive predictive value, and negative predictive value for two simple predictive models based on acute diffusion-weighted imaging lesion volume alone and acute diffusion-weighted imaging lesion volume together with the National Institutes of Health Stroke Scale after 24 h.

RESULTS

Of 135 patients, 27 (20%) developed a 'malignant' middle cerebral artery infarction. The Classification and Regression Trees analysis identified acute diffusion-weighted imaging lesion ≥78 ml and the National Institutes of Health Stroke Scale score after 24 h ≥22 as optimal cut-offs. Inclusion of the National Institutes of Health Stroke Scale score after 24 h in a simple two-step decision tree increased sensitivity from 0·59 to 0·79, while specificity, positive predictive value, and negative predictive value remained largely unchanged.

CONCLUSION

Clinical follow-up examination after 24 h helps identify patients at risk of 'malignant' middle cerebral artery infarction that are missed by predictive algorithms based on early diffusion-weighted imaging lesion volume alone.

Acute Cerebrovascular Disease in the Young

Background and Purpose—

Strokes have especially devastating implications if they occur early in life; however, only limited information exists on the characteristics of acute cerebrovascular disease in young adults. Although risk factors and manifestation of atherosclerosis are commonly associated with stroke in the elderly, recent data suggests different causes for stroke in the young. We initiated the prospective, multinational European study Stroke in Young Fabry Patients (sifap) to characterize a cohort of young stroke patients.

Methods—

Overall, 5023 patients aged 18 to 55 years with the diagnosis of ischemic stroke (3396), hemorrhagic stroke (271), transient ischemic attack (1071) were enrolled in 15 European countries and 47 centers between April 2007 and January 2010 undergoing a detailed, standardized, clinical, laboratory, and radiological protocol.

Results—

Median age in the overall cohort was 46 years. Definite Fabry disease was diagnosed in 0.5% (95% confidence interval, 0.4%–0.8%; n=27) of all patients; and probable Fabry disease in additional 18 patients. Males dominated the study population (2962/59%) whereas females outnumbered men (65.3%) among the youngest patients (18–24 years). About 80.5% of the patients had a first stroke. Silent infarcts on magnetic resonance imaging were seen in 20% of patients with a first-ever stroke, and in 11.4% of patients with transient ischemic attack and no history of a previous cerebrovascular event. The most common causes of ischemic stroke were large artery atherosclerosis (18.6%) and dissection (9.9%).

Conclusions—

Definite Fabry disease occurs in 0.5% and probable Fabry disease in further 0.4% of young stroke patients. Silent infarcts, white matter intensities, and classical risk factors were highly prevalent, emphasizing the need for new early preventive strategies.

Clinical Trial Registration Information—

URL: http://www.clinicaltrials.gov .Unique identifier: NCT00414583

Age-related changes of cerebral autoregulation: new insights with quantitative T2'-mapping and pulsed arterial spin-labeling MR imaging

BACKGROUND AND PURPOSE

Cerebral perfusion and O(2) metabolism are affected by physiologic age-related changes. High-resolution motion-corrected quantitative T2'-imaging and PASL were used to evaluate differences in deoxygenated hemoglobin and CBF of the gray matter between young and elderly healthy subjects. Further combined T2'-imaging and PASL were investigated breathing room air and 100% O(2) to evaluate age-related changes in cerebral autoregulation.

MATERIALS AND METHODS

Twenty-two healthy volunteers 60-88 years of age were studied. Two scans of high-resolution motion-corrected T2'-imaging and PASL-MR imaging were obtained while subjects were either breathing room air or breathing 100% O(2). Manual and automated regions of interest were placed in the cerebral GM to extract values from the corresponding maps. Results were compared with those of a group of young healthy subjects previously scanned with the identical protocol as that used in the present study.

RESULTS

There was a significant decrease of cortical CBF (P < .001) and cortical T2' values (P < .001) between young and elderly healthy subjects. In both groups, T2' remained unchanged under hyperoxia compared with normoxia. Only in the younger but not in the elderly group could a significant (P = .02) hyperoxic-induced decrease of the CBF be shown.

CONCLUSIONS

T2'-mapping and PASL in the cerebral cortex of healthy subjects revealed a significant decrease of deoxygenated hemoglobin and of CBF with age. The constant deoxyHb level breathing 100% O(2) compared with normoxia in young and elderly GM suggests an age-appropriate cerebral autoregulation. At the younger age, hyperoxic-induced CBF decrease may protect the brain from hyperoxemia.

Hyperintense vessels on acute stroke fluid-attenuated inversion recovery imaging: associations with clinical and other MRI findings

BACKGROUND AND PURPOSE

Hyperintense vessels (HVs) have been observed in fluid-attenuated inversion recovery imaging of patients with acute ischemic stroke and been linked to slow flow in collateral arterial circulation. Given the potential importance of HV, we used a large, multicenter data set of patients with stroke to clarify which clinical and imaging factors play a role in HV.

METHODS

We analyzed data of 516 patients from the previously published PRE-FLAIR study (PREdictive value of FLAIR and DWI for the identification of acute ischemic stroke patients≤3 and ≤4.5 hours of symptom onset-a multicenter study) study. Patients were studied by MRI within 12 hours of symptom onset. HV were defined as hyperintensities in fluid-attenuated inversion recovery corresponding to the typical course of a blood vessel that was not considered the proximal, occluded main artery ipsilateral to the diffusion restriction. Presence of HV was rated by 2 observers and related to clinical and imaging findings.

RESULTS

Presence of HV was identified in 240 of all 516 patients (47%). Patients with HV showed larger initial ischemic lesion volumes (median, 12.3 versus 4.9 mL; P<0.001) and a more severe clinical impairment (median National Institutes of Health Stroke Scale 10.5 versus 6; P<0.001). In 198 patients with MR angiography, HVs were found in 80% of patients with vessel occlusion and in 17% without vessel occlusion. In a multivariable logistic regression model, vessel occlusion was associated with HV (OR, 21.7%; 95% CI, 9.6-49.9; P<0.001). HV detected vessel occlusion with a specificity of 0.86 (95% CI, 0.80-0.90) and sensitivity of 0.76 (95% CI, 0.69-0.83).

CONCLUSIONS

HVs are a common finding associated with proximal arterial occlusions and more severe strokes. HVs predict arterial occlusion with high diagnostic accuracy.

MR volumetric changes after diagnostic CSF removal in normal pressure hydrocephalus

Although diagnostic CSF removal in patients with suspected normal pressure hydrocephalus (NPH) is performed frequently, its impact on changes of the global brain volume and volume of the ventricles has not been studied in detail. We examined 20 patients with clinical and radiological signs of NPH. These received MRI prior to and immediately after diagnostic CSF removal, either via lumbar puncture (TAP, n = 10) or via external lumbar drainage (ELD, n = 10). Changes in global brain volume were assessed using SIENA, a tool from the FSL software library. Additionally, we determined the change of the lateral ventricles' volume by manual segmentation. Furthermore, we recorded systematic clinical assessments of the key features of NPH. The median volume of CSF removed was 35 ml in TAP patients and 406 ml in ELD patients. Changes in global brain volume were found in both patient groups. Brain volume change was significantly larger in ELD patients than in TAP patients (p = 0.022), and correlated with the volume of CSF removal (r = 0.628, p = 0.004). Brain volume expansion was most pronounced adjacent to the lateral ventricles, but also detectable in the temporal and frontal regions. The median ventricular volume decreased after CSF removal. Ventricular volume reduction was more pronounced in ELD patients than in TAP patients. This study quantifies for the first time immediate volumetric changes of global brain tissue and of ventricles after diagnostic CSF removal in NPH patients. In particular, we report evidence that CSF removal results in a change of the brain volume rather than only a change of the brain's shape.

T2' imaging within perfusion-restricted tissue in high-grade occlusive carotid disease

BACKGROUND AND PURPOSE

Quantitative T2' imaging presumably detects regional changes in the relation of oxygenated and deoxygenated hemoglobin. Regional differences in hemoglobin oxygenation might reflect areas with increased oxygen extraction for compensation of reduced perfusion pressure. We investigated quantitative T2' imaging in patients with high-grade stenoses of brain-supplying arteries and hypothesized that T2' values are lower in perfusion-restricted areas as compared with normally perfused tissue.

METHODS

Eighteen patients (15 men; mean age±SD, 54±12.8 years) with unilateral symptomatic or asymptomatic high-grade extracranial or intracranial internal carotid artery or proximal middle cerebral artery stenosis/occlusion were included. MR examination included perfusion-weighted imaging and quantitative, motion-corrected mapping of T2' time. Time-to-peak and mean transit time maps were thresholded for different degrees of perfusion delays (eg, >0 seconds, ≥2 seconds) compared with the contralateral hemisphere. Mean T2' values in areas of impaired perfusion were compared with T2' values in corresponding contralateral or ipsilateral, normoperfused areas.

RESULTS

Mean size of perfusion-impaired areas in time-to-peak maps (time-to-peak delay>0 seconds) was 10.8 mL (±6.3) and 11.5 mL (±6.4) in mean transit time maps (mean transit time delay>0 seconds). T2' values were significantly (P<0.01) lower in all perfusion-restricted compared with corresponding contralateral brain areas (ipsilateral versus contralateral). For time-to-peak delay >0 seconds, T2' values were 115 ms (±9) versus 125 ms (±12). For mean transit time delay>0 seconds, T2' values were 115 ms (±9) versus 128 ms (±10). Differences in T2' values increased with the severity of the perfusion delay. Ipsilateral T2' values outside the perfusion-disturbed areas did not differ from contralateral T2' values.

CONCLUSIONS

Motion-corrected T2' imaging presumably detects areas with increased oxygen extraction within perfusion-restricted tissue in patients with high-grade occlusive vessel disease.

Abstract 2905: Changes Of Systemic Thrombolysis Rates In A Large Hospital-based Stroke Registry

Objectives: This analysis determines changes in systemic thrombolysis rates in a large state-wide stroke data set covering an observation period of 7 years following the approval of rtPA therapy in Germany.

Methods: A prospective hospital-based stroke registry covering the entire Federal State of Hesse, Germany was analyzed. All patients admitted between 2003 and 2009 with a final diagnosis of ischemic stroke (ICD-10: I63) were selected. The relationship between thrombolysis rates, onset-to-admission time, patient age, and initial stroke severity (assessed by the Modified Rankin Scale (MRS)) was analyzed. One-way ANOVA was performed to test for significant changes during the observation period.

Results: We identified 88.340 patients with ischemic stroke. Thrombolysis rates increased continuously from 2.5% in 2003 to 8.4% in 2009. In patients admitted within 3h after symptom onset, thrombolysis rate was 2.5 fold higher in 2009 (25.4%) as compared to 2003 (10.5%). Mean age (+/-SD) of thrombolyzed patients increased from 68.7 (+/-11.5) years in 2003 to 70.7 (+/-13.4) years in 2009 (p=0.014 for trend), but remained stable in the entire cohort. In contrast, stroke severity decreased both in rtPA treated patients (initial mean MRS score 3.9 in 2003 and 3.5 in 2009 (p<0.001 for trend)), and in the entire cohort (3.1 (2003); 2.9 (2009), p<0.001 for trend).

Conclusions: Thrombolytic therapy is increasingly used in acute ischemic stroke, particularly in patients admitted within the 3h time window. Several factors as improved clinical pathways, increasing personal experience and financial incentives may contribute to this development. In addition, our data suggest that higher treatment rates are at least partially explained by spreading rtPA application towards older and less severely affected patients.

Abstract 2907: Endostroke-Registry: An International Multicenter Registry for Mechanical Recanalization Procedures in Acute Stroke

Mechanical recanalization prodecures are increasingly used to treat acute large-vessel stroke. High recanalization rates in patients with proximal vessel occlusions and the direct control of therapeutic success are its major strengths. On the other hand, its clinical benefit as well as the risk/benefit ratio are not well defined by now. Randomized trials comparing endovascular approaches with systemic thrombolysis are still ongoing and present-day evidence is based on non-controlled single arm trials and case series. Within the larger studies (Penumbra Pivotal Stroke Trial, MERCI-trials) a discrepancy between favourable angiographic results and poor clinical outcomes was noticeable with high rates (up to 70%) of patients with “futile recanalization”, leading to a “clinical-angiographic mismatch”. Many factors may contribute to this paradox finding, e.g. patient selection bias (inclusion of patients with contraindications for systemic thrombolysis), too long treatment time windows and periprocedural measures (e.g. general anaesthesia). Amongt these, many other factors need clarification before mechanical recanalization therapies can be used in a broader clinical fashion. To adress some of these questions, we launched an international, investigator-driven, multicenter registry (ENDOSTROKE) to accumulate robust data on clinical outcome, complication rates and procedural issues. Its primary main outcome measure is the clinical status 90 days (or later) after intervention assessed by the MRS. Important clinical, angiographic and procedural parameters, especially time-aspects (e.g. periprocedural time loss or duration of mechanical recanalization procedures) will be analyzed with respect to their influence on clinical outcome. The registry is completely independent from industrial sponsoring and is registered at www.clinicaltrials.gov with NCT01399762 . The registry is currently recruiting patients. 13 mostly academic centers participate in the registry, 120 patients were entered by now in the database with the intention to include approximately 500 patients. At the International Stroke Conference the structure and goals of ENDOSTROKE will be presented.

Abstract 2912: Quantitative T2'-Imaging detects Increased Oxygen Extraction in High-Grade Internal Carotid and Middle Cerebral Artery Stenosis

Background and Purpose: Quantitative T2'-imaging (qT2') detects regional changes in the relation of oxygenated and deoxygenated hemoglobine (Hb) using their different signal characteristics in gradient echo imaging. In contrast to classical T2* imaging, T2’-imaging is corrected for spin-spin effects. Regional differences in Hb oxygenation might reflect areas with increased oxygen extraction for compensation of reduced perfusion pressure. The aim of the study was to investigate qT2’-imaging in perfusion-restricted areas in patients with high-grade stenoses of brain-supplying arteries. We hypothesized that T2’-values are lower in perfusion-restricted areas as compared to normal perfused tissue.

Methods: 18 patients (15 men, 3 women; mean age 54 years, SD±12.8) with sonographic unilateral symptomatic or asymtpomatic high-grade extracranial ICA stenosis/occlusion (>70%, NASCET criteria), or MR-angiographic proven unilateral high-grade (>50%) intracranial ICA or proximal MCA stenosis/occlusion were included. Patients with significant bilateral stenoses were excluded. MRI comprised perfusion-weighted imaging and quantitative, motion corrected T2’-imaging. Time-to-peak (TTP)- and mean-transit-time (MTT)-maps were thresholded for different degrees of perfusion delays (e.g. >0 sec, >2 sec) in relation to the contralateral, healthy hemisphere. Mean T2’-values in perfusion-restricted areas were compared to T2'-values in corresponding contralateral or ipsilateral, normoperfused areas. Data are given as mean (+−SD).

Results: Mean size of perfusion-restricted areas in TTP-maps (TTP-delay >0 sec) was 10.8 ml (+−6.3) and 11.5 ml (+−6.2) in MTT-maps (MTT-delay >0 sec) decreasing to 4.5 ml (+−4.7) in areas with a TTP-delay >4 sec and 6.9 ml (+−5.5) in areas with a MTT-delay >4 sec, respectively. T2'-values were significantly (p<0.01) lower in all perfusion-restricted compared to corresponding contralateral brain areas: For TTP-delay >0 sec, T2’-values were (ipsilateral) 115.2 ms (+−9) vs. (contralateral) 125.4 ms (+− 11.5). For MTT-delay >0 sec T2’-values were (ipsilateral) 114.5 ms (+−9.1) vs. (contralateral) 127.7 ms (+− 9.5). Differences in T2’-values increased with the severity of the hypoperfusion. Ipsilateral T2’-values outside the perfusion-disturbed areas did not differ from contralateral T2’-values.

Conclusions: Motion-corrected T2'-imaging detects areas with increased oxygen extraction within perfusion-restricted tissue in patients with high-grade occlusive vessel disease. T2’-imaging may add important information on the severity of the perfusion-disturbance with respect to its metabolic consequences. Its general suitability and its value for clinical decision making needs further evaluation as well as a thorough comparison with the current gold standard for the assessment of cerebral oxygen consumption, PET.

DWI-FLAIR mismatch for the identification of patients with acute ischaemic stroke within 4·5 h of symptom onset (PRE-FLAIR): a multicentre observational study

BACKGROUND

Many patients with stroke are precluded from thrombolysis treatment because the time from onset of their symptoms is unknown. We aimed to test whether a mismatch in visibility of an acute ischaemic lesion between diffusion-weighted MRI (DWI) and fluid-attenuated inversion recovery (FLAIR) MRI (DWI-FLAIR mismatch) can be used to detect patients within the recommended time window for thrombolysis.

METHODS

In this multicentre observational study, we analysed clinical and MRI data from patients presenting between Jan 1, 2001, and May 31, 2009, with acute stroke for whom DWI and FLAIR were done within 12 h of observed symptom onset. Two neurologists masked to clinical data judged the visibility of acute ischaemic lesions on DWI and FLAIR imaging, and DWI-FLAIR mismatch was diagnosed by consensus. We calculated predictive values of DWI-FLAIR mismatch for the identification of patients with symptom onset within 4·5 h and within 6 h and did multivariate regression analysis to identify potential confounding covariates. This study is registered with ClinicalTrials.gov, number NCT01021319.

FINDINGS

The final analysis included 543 patients. Mean age was 66·0 years (95% CI 64·7-67·3) and median National Institutes of Health Stroke Scale score was 8 (IQR 4-15). Acute ischaemic lesions were identified on DWI in 516 patients (95%) and on FLAIR in 271 patients (50%). Interobserver agreement for acute ischaemic lesion visibility on FLAIR imaging was moderate (κ=0·569, 95% CI 0·504-0·634). DWI-FLAIR mismatch identified patients within 4·5 h of symptom onset with 62% (95% CI 57-67) sensitivity, 78% (72-84) specificity, 83% (79-88) positive predictive value, and 54% (48-60) negative predictive value. Multivariate regression analysis identified a longer time to MRI (p<0·0001), a lower age (p=0·0009), and a larger DWI lesion volume (p=0·0226) as independent predictors of lesion visibility on FLAIR imaging.

INTERPRETATION

Patients with an acute ischaemic lesion detected with DWI but not with FLAIR imaging are likely to be within a time window for which thrombolysis is safe and effective. These findings lend support to the use of DWI-FLAIR mismatch for selection of patients in a future randomised trial of thrombolysis in patients with unknown time of symptom onset.

FUNDING

Else Kröner-Fresenius-Stiftung, National Institutes of Health.

Clinical outcome after mechanical recanalization as mono- or adjunctive therapy in acute stroke: importance of time to recanalization

BACKGROUND

The clinical benefit of mechanical recanalization procedures for acute stroke is still a matter of debate. We report the clinical and imaging results of 34 consecutive patients, focusing on time aspects (i.e. vessel occlusion time and procedure duration).

METHODS

During a 3-year period, 34 stroke patients with large-vessel occlusion (anterior circulation, n = 19; posterior circulation, n = 15) were treated with several mechanical recanalization devices with (n = 17) or without prior intravenous thrombolysis. Clinical and imaging data before (NIHSS) and after treatment [(mRS) 3 and 6-30 months] were analyzed. The angiographic outcome (TIMI score), complication rates, and procedural issues (i.e. procedure duration and vessel occlusion time) were assessed.

RESULTS

The median NIHSS on admission was 17. Successful recanalization (TIMI 2 and 3) was achieved in 23 (68%) patients. The median time from symptom onset to recanalization was 330 min, and the median time from angiography to recanalization was 101 min. Six (18%) patients had a good clinical outcome (3-month mRS ≤2), and 10 (29%) died. The vessel occlusion time was significantly shorter in patients with a good compared to poor clinical outcome (247 vs. 348 min, p = 0.024). In the subgroup of anterior circulation stroke, successful recanalization, and no symptomatic intracranial hemorrhage (n = 11), there was a strong correlation between vessel occlusion time and clinical outcome (r = 0.711, p = 0.014).

CONCLUSIONS

The rate of vessel recanalization with endovascular therapy is promising. Nevertheless, the long-term clinical outcome is still disadvantageous in the majority of patients, presumably due to too long vessel occlusion times. Better strategies for patient selection and optimization of recanalization strategies (i.e. shorter time intervals to vessel patency) are warranted.

Postthrombolysis hemorrhage risk is affected by stroke assessment bias between hemispheres

OBJECTIVE

Stroke symptoms in right hemispheric stroke tend to be underestimated in clinical assessment scales, resulting in greater infarct volumes in right as compared to left hemispheric strokes despite similar clinical stroke severity. We hypothesized that patients with right hemispheric nonlacunar stroke are at higher risk for secondary intracerebral hemorrhage after thrombolysis despite similar stroke severity.

METHODS

We analyzed data of 2 stroke cohorts with CT-based and MRI-based imaging before thrombolysis. Initial stroke severity was measured with the NIH Stroke Scale (NIHSS). Lacunar strokes were excluded through either the presence of cortical symptoms (CT cohort) or restriction to patients with prestroke diffusion-weighted imaging (DWI) lesion size >3.75 mL (MRI cohort). Probabilities of having a parenchymal hematoma were determined using multivariate logistic regression.

RESULTS

A total of 392 patients in the CT cohort and 400 patients in the MRI cohort were evaluated. Although NIHSS scores were similar in strokes of both hemispheres (median NIHSS: CT: 15 vs 13, MRI: 14 vs 16), the frequencies of parenchymal hematoma were higher in right hemispheric compared to left hemispheric strokes (CT: 12.4% vs 5.7%, MRI: 10.4% vs 6.8%). After adjustment for potential confounders (but not pretreatment lesion volume), the probability of parenchymal hematoma was higher in right hemispheric nonlacunar strokes (CT: odds ratio [OR] 2.3; 95% confidence interval [CI] 1.08-4.89; p = 0.032) and showed a borderline significant effect in the MRI cohort (OR 2.1; 95% CI 0.98-4.49; p = 0.057). Adjustment for pretreatment DWI lesion size eliminated hemispheric differences in hemorrhage risk.

CONCLUSIONS

Higher hemorrhage rates in right hemispheric nonlacunar strokes despite similar stroke severity may be caused by clinical underestimation of the proportion of tissue at bleeding risk.

Prediction of malignant middle cerebral artery infarction by magnetic resonance imaging within 6 hours of symptom onset: A prospective multicenter observational study

OBJECTIVE

Early identification of patients at risk of space-occupying "malignant" middle cerebral artery (MCA) infarction (MMI) is needed to enable timely decision for potentially life-saving treatment such as decompressive hemicraniectomy. We tested the hypothesis that acute stroke magnetic resonance imaging (MRI) predicts MMI within 6 hours of stroke onset.

METHODS

In a prospective, multicenter, observational cohort study patients with acute ischemic stroke and MCA main stem occlusion were studied by MRI including diffusion-weighted imaging (DWI), perfusion imaging (PI), and MR-angiography within 6 hours of symptom onset. Multivariate regression analysis was used to identify clinical and imaging predictors of MMI.

RESULTS

Of 140 patients included, 27 (19.3%) developed MMI. The following parameters were identified as independent predictors of MMI: larger acute DWI lesion volume (per 1 ml odds ratio [OR] 1.04, 95% confidence interval [CI] 1.02-1.06; p < 0.001), combined MCA + internal carotid artery occlusion (5.38, 1.55-18.68; p = 0.008), and severity of neurological deficit on admission assessed by the National Institutes of Health Stroke Scale score (per 1 point 1.16, 1.00-1.35; p = 0.053). The prespecified threshold of a DWI lesion volume >82 ml predicted MMI with high specificity (0.98, 95% CI 0.94-1.00), negative predictive value (0.90, 0.83-0.94), and positive predictive value (0.88, 0.62-0.98), but sensitivity was low (0.52, 0.32-0.71).

INTERPRETATION

Stroke MRI on admission predicts malignant course in severe MCA stroke with high positive and negative predictive value and may help in guiding treatment decisions, such as decompressive surgery. In a subset of patients with small initial DWI lesion volumes, repeated diagnostic tests are required.

Diffusion tensor imaging in patients with adult chronic idiopathic hydrocephalus

OBJECTIVE

Diffusion tensor imaging (DTI) parameters were investigated in patients with chronic idiopathic hydrocephalus to evaluate microstructural changes of brain tissue caused by chronic ventricular dilatation.

METHODS

Eleven patients fulfilling the criteria for possible or probable idiopathic normal pressure hydrocephalus and 10 healthy control subjects underwent MRI at 3 Tesla, including DTI with 12 gradient directions. Patients were scanned before lumbar cerebrospinal fluid (CSF) withdrawal tests. Differences in fractional anisotropy (FA) and mean diffusivity (MD) between patients and controls were assessed using 2 different methods: manual definition of regions of interest and a fully automated method, TBSS (Tract-Based Spatial Statistics). DTI parameters were correlated with clinical findings.

RESULTS

Compared with the control group, patients with chronic idiopathic hydrocephalus had significantly higher MD values in both the periventricular corticospinal tract (CST) and the corpus callosum (CC), whereas FA values were significantly higher in the CST but lower in the CC. DTI parameters of the CST correlated with the severity of gait disturbances.

CONCLUSION

Microstructural changes in periventricular functionally relevant white matter structures (CSF, CC) in chronic idiopathic hydrocephalus can be visualized using DTI. Further studies should investigate the change of DTI parameters after CSF shunting and its relation to neurologic outcome.