Validity and reliability of a quantitative computed tomography score in predicting outcome of hyperacute stroke before thrombolytic therapy. ASPECTS Study Group. Alberta Stroke Programme Early CT Score

Clinical review: Imaging in ischaemic stroke--implications for acute management

Imaging has become a cornerstone of stroke management, translating pathophysiological knowledge to everyday decision-making. Plain computed tomography is widely available and remains the standard for initial assessment: the technique rules out haemorrhage, visualizes the occluding thrombus and identifies early tissue hypodensity and swelling, which have different implications for thrombolysis. Based on evidence from positron emission tomography (PET), however, multimodal imaging is increasingly advocated. Computed tomography perfusion and angiography provide information on the occlusion site, on recanalization and on the extent of salvageable tissue. Magnetic resonance-based diffusion-weighted imaging (DWI) has exquisite sensitivity for acute ischaemia, however, and there is increasingly robust evidence that DWI combined with perfusion-weighted magnetic resonance imaging (PWI) and angiography improves functional outcome by selecting appropriate patients for thrombolysis (small DWI lesion but large PWI defect) and by ruling out those who would receive no benefit or might be harmed (very large DWI lesion, no PWI defect), especially beyond the 3-hour time window. Combined DWI–PWI also helps predict malignant oedema formation and therefore helps guide selection for early brain decompression. Finally, DWI–PWI is increasingly used for patient selection in therapeutic trials. Although further methodological developments are awaited, implementing the individual pathophysiologic diagnosis based on multimodal imaging is already refining indications for thrombolysis and offers new opportunities for management of acute stroke patients.

Stroke

Stroke is the second most common cause of death and major cause of disability worldwide. Because of the ageing population, the burden will increase greatly during the next 20 years, especially in developing countries. Advances have occurred in the prevention and treatment of stroke during the past decade. For patients with acute stroke, management in a stroke care unit, intravenous tissue plasminogen activator within 3 h or aspirin within 48 h of stroke onset, and decompressive surgery for supratentorial malignant hemispheric cerebral infarction are interventions of proven benefit; several other interventions are being assessed. Proven secondary prevention strategies are warfarin for patients with atrial fibrillation, endarterectomy for symptomatic carotid stenosis, antiplatelet agents, and cholesterol reduction. The most important intervention is the management of patients in stroke care units because these provide a framework within which further study might be undertaken. These advances have exposed a worldwide shortage of stroke health-care workers, especially in developing countries.

An acute ischemic stroke classification instrument that includes CT or MR angiography: the Boston Acute Stroke Imaging Scale

BACKGROUND AND PURPOSE

A simple classification instrument based on imaging that predicts outcomes in patients with acute ischemic stroke is lacking. We tested the hypotheses that the Boston Acute Stroke Imaging Scale (BASIS) classification instrument effectively predicts patient outcomes and is superior to the Alberta Stroke Program Early CT Score (ASPECTS) in predicting outcomes in acute ischemic stroke.

MATERIALS AND METHODS

Of 230 prospectively screened, consecutive patients with acute ischemic stroke, 87 had noncontrast CT (NCCT)/CT angiography (CTA), and 118 had MR imaging/MR angiography (MRA) at admission and were classified as having major stroke by BASIS criteria if they had a proximal cerebral artery occlusion or, if no occlusion, imaging evidence of significant parenchymal ischemia; all of the others were classified as minor strokes. Outcomes included death, length of hospitalization, and discharge disposition. BASIS was compared with ASPECTS (dichotomized > or <or=7) in 87 patients who had NCCT/CTA.

RESULTS

BASIS classification by NCCT/CTA was equivalent to MR imaging/MRA. Fifty-six of 205 patients were classified as having major strokes including all 6 of the deaths. A total of 71.4% and 15.4% of major and minor stroke survivors, respectively, were discharged to a rehabilitation facility, whereas 14.3% and 79.2% of patients with major and minor strokes were discharged to home. The mean length of hospitalization was 12.3 and 3.3 days for the major and minor stroke groups, respectively (all outcomes, P < .0001). In 87 NCCT/CTA patients, BASIS and ASPECTS agreed in 22 major and 44 minor strokes. BASIS classified 21 patients as having major strokes who were classified as having minor strokes by ASPECTS. The BASIS major/ASPECTS minor stroke group had outcomes similar to those classified as major strokes by both instruments.

CONCLUSIONS

The BASIS classification instrument is effective and appears superior to ASPECTS in predicting outcomes in acute ischemic stroke.

Guidelines for management of ischaemic stroke and transient ischaemic attack 2008

This article represents the update of the European Stroke Initiative Recommendations for Stroke Management. These guidelines cover both ischaemic stroke and transient ischaemic attacks, which are now considered to be a single entity. The article covers referral and emergency management, Stroke Unit service, diagnostics, primary and secondary prevention, general stroke treatment, specific treatment including acute management, management of complications, and rehabilitation.

[IV t-pA thrombolysis in acute stroke patients]

Intravenous administration of tissue plasminogen activator (t-PA) can improve clinical outcome in patients with acute ischemic stroke. In our country, use of t-PA for acute brain infarction within 3 hours of onset was approved by Japanese government from October, 2005. About 5,700 patients were treated with t-PA for these two years. Analysis of 2,484 patients (mean 70 years old, median NIHSS Score 15) showed that mRS 0-1 was 32%, the death was 20% and symptomatic brain hemorrhage was 5.2%. We had 63 patients (median 74 years old, median NIHSS score 14) treated with t-PA thrombolysis by November, 2007. Immediately after t-PA therapy 8 patients (12.7%) had dramatic recovery. On day 7 after t-PA therapy, excellent recovery was 49.2%, good recovery was 15.9%, and worsening was 12.7%. Within one hour after t-PA therapy, rate of recanalization for occluded arteries was 43.5%, which was strongly associated with excellent and good neurological recovery on day 7. Atrial fibrillation was an independent factor associated with no early recanalization. When we evaluated baseline DWI findings before t-PA infusion using DWI-ASPECTS and NIHSS score at day 7 after rt-PA therapy, bad outcome was seen more frequently in patients with an DWI ASPECTS < or = 5 (6 of 8 patients) than in patients with an DWI ASPECTS > 5 (2 of 41 patients; P < 0.0001). Patients with an ASPECTS-DWI > 5 should be considered eligible for t-PA therapy.

Accuracy of the Alberta Stroke Program Early CT Score during the first 3 hours of middle cerebral artery stroke: comparison of noncontrast CT, CT angiography source images, and CT perfusion

BACKGROUND AND PURPOSE

The Alberta Stroke Program Early CT Score (ASPECTS) is a reliable method of delineating the extent of middle cerebral artery (MCA) stroke. Our aim was to retrospectively compare the accuracy of ASPECTS on noncontrast CT, CT angiography (CTA) source images, and CT perfusion maps of cerebral blood volume (CBV) during the first 3 hours of middle cerebral artery (MCA) stroke.

MATERIALS AND METHODS

First-time patients with MCA stroke who presented <3 hours from symptom onset and were evaluated by noncontrast CT/CTA/CT perfusion, had confirmed acute nonlacunar MCA infarct on diffusion-weighted MR imaging (DWI) within 7 days, and had follow-up angiography were included. Patients were excluded for persistent MCA occlusion or stenosis. Two raters through consensus assigned an ASPECTS on the noncontrast CT, CTA source images, and the section-selective (2 x 12 mm coverage) CT perfusion CBV maps. ASPECTS on follow-up DWI served as the reference standard. For each CT technique, the detection rates of regional infarction, the mean ASPECTS, and the linear correlation to final ASPECTS were determined and compared. P values <.05 were considered significant.

RESULTS

Twenty-eight patients satisfied the criteria with DWI performed at a mean of 50.3 hours (range, 22-125 hours) post-CT imaging. Of 280 ASPECTS regions, 100 were infarcted on DWI. The accuracy of noncontrast CT, CTA source images, and CT perfusion CBV for detecting regional infarct was 80.0%, 84.3%, and 96.8%, respectively (P < .0001). The mean ASPECTSs of noncontrast CT, CTA source images, CT perfusion CBV, and DWI were 8.4 +/- 1.8, 8.0 +/- 1.8, 6.8 +/- 1.9, and 6.5 +/- 1.8, respectively. The mean noncontrast CT and CTA source image ASPECTS was different from that of DWI (P < .05). Correlation of noncontrast CT, CTA source images, and CT perfusion CBV ASPECTS with final ASPECTS was r(2) = 0.34, r(2) = 0.42, and r(2) = 0.91, respectively.

CONCLUSION

In a retrospective cohort of MCA infarcts imaged <3 hours from stroke onset, ASPECTS was most accurately determined on CT perfusion CBV maps.

Association of pretreatment ASPECTS scores with tPA-induced arterial recanalization in acute middle cerebral artery occlusion

BACKGROUND AND PURPOSE

The Alberta Stroke Program Early CT-Score (ASPECTS) assesses early ischemic changes within the middle cerebral artery (MCA) and predicts poor outcome and increased risk for thrombolysis-related symptomatic ICH. We evaluated the potential relationship between pretreatment ASPECTS and tPA-induced recanalization in patients with MCA occlusions.

SUBJECTS & METHODS

Consecutive patients with acute ischemic stroke due to MCA occlusion were treated with standard IV-tPA and assessed with transcranial Doppler (TCD) for arterial recanalization. Early recanalization was determined with previously validated Thrombolysis in Brain Ischemia (TIBI) flow-grading system at 120 minutes after tPA-bolus. All pretreatment CT-scans were prospectively scored by trained investigators blinded to TCD findings. Functional outcome at 3 months was evaluated using the modified Rankin Scale (mRS).

RESULTS

IV-tPA was administered in 192 patients (mean age 68 +/- 14 years, median NIHSS-score 17). Patients with complete recanalization (n= 51) had higher median pretreatment ASPECTS (10, interquartile range 2) than patients with incomplete or absent recanalization (n= 141; median ASPECTS 9, interquartile range 3, P= .034 Mann-Whitney U-test). An ASPECTS < or =6 was documented in 4% and 17% of patients with present and absent recanalization, respectively (P= .019). Pretreatment ASPECTS was associated with complete recanalization (OR per 1-point increase: 1.54; 95% CI 1.06-2.22, P= .023) after adjustment for baseline characteristics, risk factors, NIHSS-score, pretreatment TIBI grades and site of arterial occlusion on baseline TCD. Complete recanalization (OR: 33.97, 95% CI 5.95-185.99, P < .001) and higher ASPECTS (OR per 1-point increase: 1.91; 95% CI 1.17-3.14, P= .010) were independent predictors of good functional outcome (mRS 0-2).

CONCLUSIONS

Higher pretreatment ASPECT-scores are associated with a greater chance of complete recanalization and favorable long-term outcome in tPA-treated patients with acute MCA occlusion.

Risk for symptomatic intracerebral hemorrhage after thrombolysis assessed by diffusion-weighted magnetic resonance imaging

OBJECTIVE

The risk for symptomatic intracerebral hemorrhage (sICH) associated with thrombolytic treatment has not been evaluated in large studies using diffusion-weighted imaging (DWI). Here, we investigated the relation between pretreatment DWI lesion size and the risk for sICH after thrombolysis.

METHODS

In this retrospective multicenter study, prospectively collected data from 645 patients with anterior circulation stroke treated with intravenous or intraarterial thrombolysis within 6 hours (<3 hours: n = 320) after symptom onset were pooled. Patients were categorized according to the pretreatment DWI lesion size into three prespecified groups: small (< or =10 ml; n = 218), moderate (10-100 ml; n = 371), and large (>100 ml; n = 56) DWI lesions.

RESULTS

In total, 44 (6.8%) patients experienced development of sICH. The sICH rate was significantly different between subgroups: 2.8, 7.8, and 16.1% in patients with small, moderate, and large DWI lesions, respectively (p < 0.05). This translates to a 5.8 (2.8)-fold greater sICH risk for patients with large DWI lesions as compared with patients with small (or moderate) DWI lesions. The results were similar in the large subgroup (n = 536) of patients treated with intravenous tissue plasminogen activator. DWI lesion size remained an independent risk factor when including National Institutes of Health Stroke Scale, age, time to thrombolysis, and leukoariosis in a logistic regression analysis.

INTERPRETATION

This multicenter study provides estimates of sICH risk in potential candidates for thrombolysis. The sICH risk increases gradually with increasing DWI lesion size, indicating that the potential benefit of therapy needs to be balanced carefully against the risk for sICH, especially in patients with large DWI lesions.

Recanalization between 1 and 24 hours after t-PA therapy is a strong predictor of cerebral hemorrhage in acute ischemic stroke patients

BACKGROUND AND PURPOSE

Intravenous administration of tissue plasminogen activator (t-PA) can improve clinical outcomes in patients with acute ischemic stroke. The most important complication of t-PA therapy is intracerebral hemorrhage (ICH). The aim of this study was to use serial MRI studies to identify independent predictors of symptomatic and asymptomatic ICH after t-PA therapy.

METHODS

Consecutive anterior-circulation ischemic stroke patients treated with t-PA within 3 h of stroke onset were studied prospectively. To identify the presence of recanalization in the occluded arteries and the presence of ICH, MRI, including diffusion weighted imaging (DWI), T2*, and magnetic resonance angiography (MRA), was performed before and 1 h, 24 h, and 5-7 days after t-PA thrombolysis. The independent predictors of ICH were determined using multivariate logistic regression analysis.

RESULTS

41 patients (21 males, 20 females; mean age, 73.2+/-10.7 years) were enrolled, and 19 ICHs (1 symptomatic, 18 asymptomatic) were observed on T2*. The initial MRA demonstrated occluded brain arteries in 31 patients (75.6%), of which follow-up MRA at 1 h, 24 h, and 5-7 days after t-PA therapy revealed recanalization in 48.4%, 80.0%, and 90.0% of patients, respectively. The frequency of recanalization within 1 h after t-PA therapy did not differ between ICH and No-ICH groups, but the ICH group had more frequent recanalization between 1 h and 24 h after t-PA than the No-ICH group (50.0% vs. 4.5%, P=0.001). The ICH group had arterial fibrillation (AF) more frequently than the No-ICH group (78.9% vs. 27.3%, P=0.001). Compared to the No-ICH group, the NIHSS score was higher (16.4+/-5.7 vs. 11.5+/-6.5, P=0.011) and the ASPECTS-DWI value (a normal DWI has an ASPECTS-DWI value of 11 points) was lower (7.3+/-2.4 vs. 8.9+/-1.9, P=0.019) in the ICH group. Multivariate logistic regression analysis demonstrated that the presence of recanalization between 1 and 24 h after the end of t-PA infusion (OR: 20.2; CI: 1.0-340.9; P=0.037) was the only independent predictor of ICH.

CONCLUSION

Recanalization of occluded arteries between 1 and 24 h but not within 1 h after t-PA infusion should be independently associated with symptomatic and asymptomatic ICH after t-PA therapy.

Comparison of two imaging protocols for acute stroke: unenhanced cranial CT versus a multimodality cranial CT protocol with perfusion imaging

The aim of the study was to validate a multimodality cranial computed tomography (CCT) protocol for patients with acute stroke in the United Arab Emirates as a basic imaging procedure for a stroke unit. Therefore, a comparative study was conducted between two groups: retrospective, historical group 1 with early unenhanced CCT and prospective group 2 undergoing a multimodality CCT protocol. Follow-up unenhanced CCT>48 h served as gold standard in both groups. Group 1: Early unenhanced CCT of 50 patients were evaluated retrospectively, using Alberta Stroke Program Early CT Score, and compared with the definite infarction on follow-up CCT. Group 2: 50 patients underwent multimodality CCT (unenhanced CCT, perfusion studies: cerebral blood flow, cerebral blood volume, mean transit time and CT angiography)<8 h after clinical onset and follow-up studies. Modified National Institute of Health Stroke Scale was used clinically in both groups. Group 1 showed 38 men, 12 women, clinical onset 2-8 h before CCT and modified National Institute of Health Stroke Scale 0-28. Group 2 included 38 men, 12 women, onset 3-8 h before CCT, modified National Institute of Health Stroke Scale 0-28. Sensitivity was 58.3% in group 1 and 84.2% in group 2. Computed tomography angiography detected nine intracranial occlusions/stenoses. The higher sensitivity of the multimodality CCT protocol justifies its use as a basic diagnostic tool for the set-up of a first-stroke unit in the United Arab Emirates.

Rapid Assessment of Perfusion–Diffusion Mismatch

Background and Purpose— For MR perfusion–diffusion (PWI-DWI) mismatch to become routine in thrombolysis patient selection, rapid and reliable assessment tools are required. We examined interrater variability in PWI/DWI volume measurements and developed a rapid assessment tool based on the Alberta Stroke Program Early CT Scores (ASPECTS) system.

Methods— DWI and PWI were performed in 35 patients with stroke <6 hours after symptom onset. DWI lesion and PWI (time to peak) volumes were measured with planimetric techniques by 4 raters and the 95% limits of agreement calculated. ASPECT scores were assessed separately by 4 investigators (2 experienced and 2 inexperienced) for DWI (MR DWI scores) and PWI (MR time to peak scores). MR mismatch scores were calculated as MR DWI-MR time to peak scores.

Results— Interobserver variability was much greater for PWI (95% limit of agreement=±72.3 mL) than for DWI (95% limit of agreement=±12.6 mL). A semiautomated PWI volume (time to peak+2 s) was therefore used to calculate mismatch volume. MR mismatch scores ≥2 predicted 20% PWI-DWI mismatch by volume with mean 78% sensitivity (range, 72% to 84%) and 88% specificity (range, 83% to 90%). There was excellent agreement on mismatch classification using MR mismatch scores between experienced raters (weighted kappa scores of 0.94) with agreement in 34 of 35 cases. Agreement was less consistent between inexperienced raters (weighted kappa=0.49, 28 of 35 cases).

Conclusions— Variability in planimetric mismatch measurements arises primarily from differences in PWI volume assessment. High specificity and interrater reliability may make MR mismatch scores an ideal rapid screening tool for potential thrombolysis patients.

Alberta Stroke Program Early CT Scoring of CT perfusion in early stroke visualization and assessment

BACKGROUND AND PURPOSE

Qualitative CT perfusion (CTP) assessment by using the Alberta Stroke Program Early CT Score (ASPECTS) allows rapid calculation of infarct extent for middle cerebral artery infarcts. Published thresholds exist for noncontrast CT (NCCT) ASPECTS, which may distinguish outcome/complication risk, but early ischemic signs are difficult to detect. We hypothesized that different ASPECTS thresholds exist for CTP parameters versus NCCT and that these may be superior at predicting clinical and radiologic outcome in the acute setting.

MATERIALS AND METHODS

Thirty-six baseline acute stroke NCCT and CTP studies within 3 hours of symptoms were blindly reviewed by 3 neuroradiologists, and ASPECTS were assigned. Treatment response was defined as major neurologic improvement when a > or =8-point National Institutes of Health Stroke Scale improvement at 24 hours occurred. Follow-up NCCT ASPECTS and 90-day modified Rankin score (mRS) were radiologic and clinical reference standards. Receiver operating characteristic curves derived optimal thresholds for outcome.

RESULTS

Cerebral blood volume and NCCT ASPECTS had similar radiologic correlations (0.6 and 0.5, respectively) and best predicted infarct size in the absence of major neurologic improvement. A NCCT ASPECT threshold of 7 and a cerebral blood volume threshold of 8 discriminated patients with poor follow-up scans (P < .0002 and P = .0001) and mRS < or =2 (P = .001 and P < .001). Only cerebral blood volume predicted major neurologic improvement (P = .02). Interobserver agreement was substantial (intraclass correlation coefficient, 0.69). Cerebral blood volume ASPECTS sensitivity, specificity, positive predictive value, and negative predictive value for clinical outcome were 60%, 100%, 100%, and 45%, respectively. No patients with cerebral blood volume ASPECTS <8 achieved good clinical outcome.

CONCLUSION

Cerebral blood volume ASPECTS is equivalent to NCCT for predicting radiologic outcome but may have an additional benefit in predicting patients with major neurologic improvement.

Can the Ischemic Penumbra Be Identified on Noncontrast CT of Acute Stroke?

Background and Purpose— Early ischemic changes on noncontrast CT in acute stroke include both hypoattenuation and brain swelling, which may have different pathophysiological significance.

Methods— Noncontrast CT and CT perfusion brain scans from patients with suspected acute stroke <6 hours after onset were reviewed. Five raters independently scored noncontrast CTs blind to clinical data using the Alberta Stroke Program Early CT Score (ASPECTS). Each ASPECTS region was scored as hypodense or swollen. A separate reviewer measured time to peak and cerebral blood volume in each ASPECTS region on CT perfusion. Time to peak and cerebral blood volume were compared for each region categorized as normal, hypodense, or isodense and swollen.

Results— Scans of 32 subjects a median 155 minutes after onset yielded 228 regions with both CT perfusion and noncontrast CT data. Isodense swelling was associated with significantly higher cerebral blood volume ( P =0.016) and with penumbral perfusion (posttest:pretest likelihood ratio 1.44 [95% CI: 0.68 to 2.90]), whereas hypodensity was associated with more severe time to peak delay and with core perfusion (likelihood ratio 3.47 [95% CI: 1.87 to 6.34]). Neither isodense swelling nor hypodensity was sensitive for prediction of perfusion pattern, but appearances were highly specific (87.2% and 91.0% for penumbra and core, respectively). Intrarater agreement was good or excellent, but interrater agreement for both hypodensity and swelling was poor.

Conclusions— Regions exhibiting hypoattenuation are likely to represent the infarct core, whereas regions that are isodense and swollen have increased cerebral blood volume and are more likely to signify penumbral perfusion. Although noncontrast CT is not sensitive for detection of core and penumbra, appearances are specific. Some information on tissue viability can therefore be obtained from noncontrast CT.

[Development of an algorithm for the detection of early signs of cerebral ischemia on CT images]

This paper describes an approach to automatically detect the parenchymal hypoattenuation of hyperacute stroke in nonenhanced computed tomography (CT) images. This technique is based on a comparison between the CT values histograms of right and left brains. A subtraction curve that was regarded as an output value was calculated by subtracting the right-hemispherical histogram from the left-hemispherical histogram obtained from one of the region-of-interest (ROI) sets on an image. The output value was used to assess whether hypoattenuation exists on CT images with a threshold value. If judged abnormal, a rectangular region including a whole or partial hypoattenuation area was detected from the ROI. Twenty-six cases with hypoattenuation and 30 cases without hypoattenuation were included in this study. As a result of our experiments, the sensitivity of this method in detecting hypoattenuation was found to be 92%, with approximately 0.16 false-positive per image. Our preliminary experimental results indicated that the proposed technique can be used for the automated detection of parenchymal hypoattenuation of hyperacute stroke on nonenhanced CT images.

Combined intravenous and intra-arterial approach in acute stroke treatment

Despite the significant improvement in the outcome of ischaemic stroke with the use of intravenous recombinant tissue plasminogen activator, experience has shown limitations of the sole use of this approach in acute stroke treatment. This has encouraged the search for alternative managements for acute stroke. The combined use of intravenous/intra-arterial therapy is one such alternate treatment, if used in the right setting. In this review, the authors discuss the advantages and limitations of using this approach, together with an overview of the available therapies used through each route. The authors discuss the process of patient selection using clinical, as well as state of the art imaging modalities.

Assessment of suitability of thrombolysis in middle cerebral artery infarction: a proof of concept study of a stereologically-based technique

BACKGROUND

The extent of cerebral ischemia, assessed by the Alberta Stroke Program Early CT Score (ASPECTS) method and unaided visual determination of the CT Summit Criterion, correlates with increased risk of intracerebral hemorrhage following rt-PA administration. Concerns about the accuracy of the unaided visual assessment in the estimation of infarct size and the conservative nature of the ASPECTS method led us to develop a new method (MCAGrid) based on stereological grid counting and a digital atlas of the middle cerebral artery (MCA) infarct territory.

METHODS

We tested the hypotheses that the stereological method increases the accuracy of infarct estimation and that the number of patients deemed eligible for thrombolysis is greater with this method than with existing methods. Four experienced radiologists with extensive neuroradiological experience examined the CT images of 19 patients with MCA territory stroke and determined patient eligibility for thrombolysis by: unaided visual determination of the CT Summit Criterion, MCAGrid, and the ASPECTS score. The chi(2) test was used to compare the differences in the number of patients deemed 'eligible' for thrombolysis by the 3 imaging methods. Further, the unaided visual assessment and MCAGrid were compared with volumes calculated following manual segmentation of infarct, and the sensitivity, specificity and positive and negative likelihood ratios for these techniques were calculated.

RESULTS

In general, MCAGrid was better than unaided visual assessment in the prediction of >1/3 involvement of the MCA territory by infarct. The number of patients considered as 'eligible' for thrombolysis based on imaging criteria was significantly lower when ASPECTS criteria (15/76) were used than when unaided visual determination of the CT Summit Criterion (32/76; p < 0.01) or MCAGrid (59/76; p < 0.001) criteria were used.

CONCLUSION

The choice of methods for rating infarct extent affects the number of patients 'eligible' for thrombolysis significantly. Furthermore, MCAGrid increased the accuracy with which infarct extent was estimated. These results provide justification for a prospective study of this technique in the setting of acute stroke.

Factors predicting hemorrhagic complications after multimodal reperfusion therapy for acute ischemic stroke

BACKGROUND AND PURPOSE

We sought to find predictors for hemorrhagic complications in patients with acute ischemic stroke treated with multimodal endovascular therapy.

MATERIALS AND METHODS

We retrospectively reviewed patients with acute ischemic stroke treated with multimodal endovascular therapy from May 1999 to March 2006. We reviewed clinical and angiographic data, admission CT Alberta Stroke Programme Early CT Score (ASPECTS), and the therapeutic endovascular interventions used. Posttreatment CT scans were reviewed for the presence of a parenchymal hematoma or hemorrhagic infarction based on defined criteria. Predictors for these types of hemorrhages were determined by logistic regression analysis.

RESULTS

We identified 185 patients with a mean age of 65+/-13 years and mean National Institutes of Health Stroke Scale score of 17+/-4. Sixty-nine patients (37%) developed postprocedural hemorrhages: 24 (13%) parenchymal hematomas and 45 (24%) hemorrhagic infarctions. Patients with tandem occlusions (odds ratio [OR] 4.6 [1.4-6.5], P<.016), hyperglycemia (OR 2.8 [1.1-7.7], P<.043), or treated concomitantly with intravenous (IV) tissue plasminogen activator (tPA) and intra-arterial (IA) urokinase (OR 5.1 [1.1-25.0], P<.041) were at a significant risk for a parenchymal hematoma. Hemorrhagic infarction occurred significantly more in patients presenting with an ASPECTS

CONCLUSIONS

Hemorrhagic infarctions are related to the extent of infarct based on presentation CT, whereas parenchymal hematomas are associated with the presence of tandem occlusions, hyperglycemia, and treatment with both IV tPA and IA urokinase in patients with acute stroke treated with multimodal endovascular therapy.

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MESH Headings

• Acute Disease
• Aged
• Brain Ischemia/epidemiology
• Brain Ischemia/therapy
• Cerebral Hemorrhage/epidemiology
• Comorbidity
• Female
• Humans
• Male
• Middle Aged
• Pennsylvania/epidemiology
• Prevalence
• Reperfusion/statistics & numerical data
• Risk Assessment/methods
• Risk Factors
• Stroke/epidemiology
• Stroke/therapy
• Treatment Outcome

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Affiliation(s)

N A Vora Department of Neurology, Stroke Institute, University of Pittsburgh, Medical Center, Pittsburgh, PA 15213, USA
R Gupta
A J Thomas
M B Horowitz
A H Tayal
M D Hammer
K Uchino
L R Wechsler
T G Jovin

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Novel noise reduction filter for improving visibility of early computed tomography signs of hyperacute stroke: evaluation of the filter's performance—preliminary clinical experience

PURPOSE

The aim of this study was to evaluate the performance of a novel noise reduction filter for improving the visibility of early computed tomography (CT) signs of hyperacute stroke on nonenhanced CT images.

MATERIAL AND METHODS

Fourteen patients with a middle cerebral artery occlusion within 4.5 h after onset were evaluated. The signal-to-noise ratio (SNR) of the processed images with the noise reduction filter and that of original images were measured. Two neuroradiologists visually rated all the processed and original images on the visibility of normal and abnormal gray-white matter interfaces.

RESULTS

The SNR value of the processed images was approximately eight times as high as that of the original images, and a 87% reduction of noise was achieved using this technique. For the visual assessment, the results showed that the visibility of normal gray-white matter interface and that of the loss of the gray-white matter interface were significantly improved using the proposed method (P < 0.05).

CONCLUSION

The noise reduction filter proposed in the present study has the potential to improve the visibility of early CT signs of hyperacute stroke on nonenhanced CT images.

Acute Stroke Imaging for Thrombolytic Therapy – An Update

More than ten years after its approval intravenous thrombolysis with rtPA still is the only approved therapy for acute ischemic stroke. In this review we aim to give an up-to-date overview of acute stroke imaging within and outside of approved indications for thrombolysis. We discuss the potential applications of modern CT techniques such as CT angiography and perfusion CT as well as stroke MRI for the selection-based treatment of acute ischemic stroke. Recent publications regarding diagnostic strength as well as new randomized trials and larger prospective but open studies are reviewed and discussed. Finally we present a suggestion for the selection of patients for thrombolysis within and beyond the 3-hour time window in the form of an institutional algorithm prioritizing according to present evidence and pathophysiological reasoning.

Acute brain infarct: detection and delineation with CT angiographic source images versus nonenhanced CT scans

PURPOSE

To retrospectively compare sensitivity and specificity of admission nonenhanced computed tomographic (CT) scans with those of CT angiographic source images in detection of early ischemic changes in middle cerebral artery (MCA) stroke and to retrospectively compare admission nonenhanced CT scans with CT angiographic source images in delineation of final infarct extent, with follow-up images as reference.

MATERIALS AND METHODS

Informed consent and institutional review board approval were received for this HIPAA-compliant study. Nonenhanced scans and angiographic source images obtained within 12 hours of symptom onset in 51 patients suspected of having MCA stroke were reviewed. Two blinded neuroimagers rated presence and extent of hypoattenuation on nonenhanced scans and angiographic source images with Alberta Stroke Programme Early CT Score (ASPECTS). Level of certainty for hypoattenuation detection was assigned a grade with a five-point scale. With receiver operating characteristic (ROC) curve analysis, nonenhanced scans and angiographic source images were compared for stroke detection. For stroke delineation, linear regression coefficients determined correlations of ASPECTS for nonenhanced scans and angiographic source images with ASPECTS for follow-up images. Multiple linear regressions were used to compare these correlations.

RESULTS

Follow-up nonenhanced CT scans, diffusion-weighted magnetic resonance (MR) images, or fluid-attenuated inversion-recovery MR images were obtained (mean time to follow-up, 5.4 days); 33 patients had infarction. With level of certainty cutoff score of 4 or greater (probable, definite) for ischemic hypoattenuation, sensitivity for detection of acute stroke was 48% (nonenhanced scans) and 70% (angiographic source images) (P = .04, ROC analysis); specificity was 100% for both. Linear regression revealed R(2) = 0.42 (P < .001) for correlation between delineation of stroke on nonenhanced scans and on follow-up images evaluated with ASPECTS and 0.73 (P < .001) for correlation between delineation on angiographic source images and follow-up images evaluated with ASPECTS (P < .001, nonenhanced scans vs angiographic source images).

CONCLUSION

CT angiographic source images, compared with nonenhanced CT scans, are more sensitive in detection of early irreversible ischemia and more accurate for prediction of final infarct volume.

Risk factors of symptomatic intracerebral hemorrhage after tPA therapy for acute stroke

BACKGROUND

Studies evaluating predictors of tPA-associated symptomatic intracerebral hemorrhage (SICH) have typically focused on clinical and CT-based variables. MRI-based variables have generally not been included in predictive models, and little is known about the influence of reperfusion on SICH risk.

METHODS

Seventy-four patients were prospectively enrolled in an open-label study of intravenous tPA administered between 3 and 6 hours after symptom onset. An MRI was obtained before and 3 to 6 hours after tPA administration. The association between several clinical and MRI-based variables and tPA-associated SICH was determined using multivariate logistic regression analysis. SICH was defined as a > or = 2 point change in National Institutes of Health Stroke Scale Score (NIHSSS) associated with any degree of hemorrhage on CT or MRI. Reperfusion was defined as a decrease in PWI lesion volume of at least 30% between baseline and the early follow-up MRI.

RESULTS

SICH occurred in 7 of 74 (9.5%) patients. In univariate analysis, NIHSSS, DWI lesion volume, PWI lesion volume, and reperfusion status were associated with an increased risk of SICH (P<0.05). In multivariate analysis, DWI lesion volume was the single independent baseline predictor of SICH (odds ratio 1.42; 95% CI 1.13 to 1.78 per 10 mL increase in DWI lesion volume). When early reperfusion status was included in the predictive model, the interaction between DWI lesion volume and reperfusion status was the only independent predictor of SICH (odds ratio 1.77; 95% CI 1.25 to 2.50 per 10 mL increase in DWI lesion volume).

CONCLUSIONS

Patients with large baseline DWI lesion volumes who achieve early reperfusion appear to be at greatest risk of SICH after tPA therapy.

Perfusion CT in acute stroke: prediction of vessel recanalization and clinical outcome in intravenous thrombolytic therapy

This study evaluated perfusion computed tomography (PCT) for the prediction of vessel recanalization and clinical outcome in patients undergoing intravenous thrombolysis. Thirty-nine patients with acute ischemic stroke of the middle cerebral artery territory underwent intravenous thrombolysis within 3 h of symptom onset. They all had non-enhanced CT (NECT), PCT, and CT angiography (CTA) before treatment. The Alberta Stroke Program Early Computed Tomography (ASPECT) score was applied to NECT and PCT maps to assess the extent of ischemia. CTA was assessed for the site of vessel occlusion. The National Institute of Health Stroke Scale (NIHSS) score was used for initial clinical assessment. Three-month clinical outcome was assessed using the modified Rankin scale. Vessel recanalization was determined by follow-up ultrasound. Of the PCT maps, a cerebral blood volume (CBV) ASPECT score of >6 versus < or =6 was the best predictor for clinical outcome (odds ratio, 31.43; 95% confidence interval, 3.41-289.58; P < 0.002), and was superior to NIHSS, NECT and CTA. No significant differences in ASPECT scores were found for the prediction of vessel recanalization. ASPECT score applied to PCT maps in acute stroke patients predicts the clinical outcome of intravenous thrombolysis and is superior to both early NECT and clinical parameters.

CT-NIHSS mismatch does not correlate with MRI diffusion-perfusion mismatch

BACKGROUND AND PURPOSE

MRI diffusion-perfusion mismatch may identify patients for thrombolysis beyond 3 hours. However, MRI has limited availability in many hospitals. We investigated whether mismatch between the Alberta Stroke Program Early CT Score (ASPECTS) and the NIH Stroke Scale (NIHSS) correlates with MRI diffusion-perfusion mismatch.

METHODS

We retrospectively analyzed a cohort of consecutive acute ischemic stroke patients who underwent MRI and CT at admission. NIHSS was performed by the admitting physician. MRI and CT were reviewed by 2 blinded expert raters. Degree of MRI mismatch was defined as present (> 25%) or absent (<25%). Univariate and multivariate analyses were performed to determine characteristics associated with MRI mismatch. Probability of MRI mismatch was calculated for all combinations of ASPECTS and NIHSS cutoff scores.

RESULTS

Included in the analysis were 143 patients. Median NIHSS on admission was 4 (IQR, 2 to 10); median ASPECTS was 10 (IQR, 9 to 10). Median time to completion of MRI and CT was 4.5 (2.5 to 13.9) hours after onset. CT and MRI were separated by a median of 35 (IQR, 29 to 44) minutes. MRI mismatch was present in 41% of patients. In multivariate analysis, only shorter time-to-scan (OR, 0.96 per hour; 95% CI, 0.92 to 1.0; P=0.043) was associated with MRI mismatch. There was no combination of NIHSS and ASPECTS thresholds that was significantly associated with MRI mismatch.

CONCLUSIONS

ASPECTS-NIHSS mismatch did not correlate with MRI diffusion-perfusion mismatch in this clinical cohort. MRI mismatch was associated with decreasing time from stroke onset to scan.

Symptomatic intracerebral hemorrhage following thrombolytic therapy for acute ischemic stroke: a review of the risk factors

BACKGROUND

Symptomatic intracerebral hemorrhage (SICH) following thrombolytic therapy for acute ischemic stroke is associated with a high rate of morbidity and mortality. Knowledge of the risk factors associated with SICH following thrombolyitc therapy may provide insight into the pathophysiological mechanisms underlying the development of SICH, lead to the development of treatments that reduce the risk of SICH and have implications for the design of future stroke trials.

METHODS

Relevant studies were identified through a search in Pubmed. Included studies used multivariate analyses to identify independent risk factors for SICH following thrombolytic therapy. For each variable that was found to have a significant association with SICH, a secondary literature search was conducted to identify additional reports on the specific relationship between that variable and SICH.

SUMMARY OF REVIEW

Twelve studies met inclusion criteria for the systematic review. Extent of hypoattenuated brain parenchyma on pretreatment CT and elevated serum glucose or history of diabetes were independent risk factors for thrombolysis-associated SICH in six of the twelve studies. Symptom severity was an independent risk factor in three of the studies and advanced age, increased time to treatment, high systolic blood pressure, low platelets, history of congestive heart failure and low plasminogen activator inhibitor levels were found to be independent risk factors for SICH in a single study. Although these data should not alter the current guidelines for the use of rt-PA in acute stroke, they may help develop future strategies aimed at reducing the rate of thrombolysis-associated SICH.

Guidelines for the Early Management of Adults With Ischemic Stroke

Purpose— Our goal is to provide an overview of the current evidence about components of the evaluation and treatment of adults with acute ischemic stroke. The intended audience is physicians and other emergency healthcare providers who treat patients within the first 48 hours after stroke. In addition, information for healthcare policy makers is included.

Methods— Members of the panel were appointed by the American Heart Association Stroke Council’s Scientific Statement Oversight Committee and represented different areas of expertise. The panel reviewed the relevant literature with an emphasis on reports published since 2003 and used the American Heart Association Stroke Council’s Levels of Evidence grading algorithm to rate the evidence and to make recommendations. After approval of the statement by the panel, it underwent peer review and approval by the American Heart Association Science Advisory and Coordinating Committee. It is intended that this guideline be fully updated in 3 years.

Results— Management of patients with acute ischemic stroke remains multifaceted and includes several aspects of care that have not been tested in clinical trials. This statement includes recommendations for management from the first contact by emergency medical services personnel through initial admission to the hospital. Intravenous administration of recombinant tissue plasminogen activator remains the most beneficial proven intervention for emergency treatment of stroke. Several interventions, including intra-arterial administration of thrombolytic agents and mechanical interventions, show promise. Because many of the recommendations are based on limited data, additional research on treatment of acute ischemic stroke is needed.

Serum cellular fibronectin and matrix metalloproteinase-9 as screening biomarkers for the prediction of parenchymal hematoma after thrombolytic therapy in acute ischemic stroke: a multicenter confirmatory study

BACKGROUND AND PURPOSE

Plasma levels of cellular fibronectin (c-Fn) > or =3.6 microg/mL and of matrix metalloproteinase-9 (MMP-9) > or =140 ng/mL have been associated with parenchymal hematoma (PH) after treatment with tissue-type plasminogen activator (t-PA) in patients with acute ischemic stroke. In this prospective study, we sought to validate the predictive capacity of the preestablished cutoff values of these biomarkers for PH in a larger series of patients.

METHODS

We studied 134 patients treated with t-PA within 3 hours from symptom onset according to the SITS-MOST criteria (median time to infusion, 152 minutes; median National Institutes of Health Stroke Scale score, 14) in 4 university hospitals. Hemorrhagic transformation was classified according to the European-Australasian Acute Stroke Study II definitions on computed tomography scans performed 24 to 36 hours after treatment. Relevant hemorrhagic transformation was defined as hemorrhagic infarction type 2 or any PH. Serum c-Fn and MMP-9 levels were determined by an ELISA om blood samples obtained before treatment.

RESULTS

Cranial computed tomography showed hemorrhagic transformation in 27 patients (20%), hemorrhagic infarction in 15 (type 2 in 8 patients), and PH in 12 patients (symptomatic in 4). Serum c-Fn and MMP-9 concentrations at baseline were significantly higher in patients with relevant hemorrhagic transformation and PH than in those without (all P<0.001). The sensitivity, specificity, and positive and negative predictive values for PH by c-Fn levels > or =3.6 microg/mL were 100%, 60%, 20%, and 100%, respectively, whereas corresponding values were 92%, 74%, 26%, and 99% for MMP-9 levels > or =140 ng/mL. When both biomarkers were at levels above the cutoff points, specificity increased to 87% and the positive predictive value increased to 41%.

CONCLUSIONS

This prospective study confirmed the high sensitivity and negative predictive value, with retained good specificity, of c-Fn and MMP-9 for the prediction of PH in patients treated with t-PA. Development of faster analytic methods will prove the applicability of these biomarkers in routine clinical practice.

Role of transcranial Doppler ultrasonography in evaluation of patients with cerebrovascular disease

Transcranial Doppler ultrasonography (TCD) is the only noninvasive examination method that enables the reliable evaluation of blood flow from the basal intracerebral vessels, adding physiologic information to the anatomic images. TCD is relatively inexpensive, can be performed at bedside, and allows monitoring in acute emergency settings and for prolonged periods with a high temporal resolution, making it ideal for studying dynamic cerebrovascular responses. In acute stroke, TCD is capable of providing rapid information about the hemodynamic status of the cerebral circulation and monitoring recanalization in real-time, with a potential for enhancing tissue plasminogen activator-induced thrombolysis. Extended applications such as emboli monitoring, right-to-left shunt detection, and vasomotor reactivity make TCD an important and valuable tool for evaluating stroke mechanisms, planning and monitoring treatment, and determining prognosis.

Guidelines for the early management of adults with ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council, Clinical Cardiology Council, Cardiovascular Radiology and Intervention Council, and the Atherosclerotic Peripheral Vascular Disease and Quality of Care Outcomes in Research Interdisciplinary Working Groups: the American Academy of Neurology affirms the value of this guideline as an educational tool for neurologists

PURPOSE

Our goal is to provide an overview of the current evidence about components of the evaluation and treatment of adults with acute ischemic stroke. The intended audience is physicians and other emergency healthcare providers who treat patients within the first 48 hours after stroke. In addition, information for healthcare policy makers is included.

METHODS

Members of the panel were appointed by the American Heart Association Stroke Council's Scientific Statement Oversight Committee and represented different areas of expertise. The panel reviewed the relevant literature with an emphasis on reports published since 2003 and used the American Heart Association Stroke Council's Levels of Evidence grading algorithm to rate the evidence and to make recommendations. After approval of the statement by the panel, it underwent peer review and approval by the American Heart Association Science Advisory and Coordinating Committee. It is intended that this guideline be fully updated in 3 years.

RESULTS

Management of patients with acute ischemic stroke remains multifaceted and includes several aspects of care that have not been tested in clinical trials. This statement includes recommendations for management from the first contact by emergency medical services personnel through initial admission to the hospital. Intravenous administration of recombinant tissue plasminogen activator remains the most beneficial proven intervention for emergency treatment of stroke. Several interventions, including intra-arterial administration of thrombolytic agents and mechanical interventions, show promise. Because many of the recommendations are based on limited data, additional research on treatment of acute ischemic stroke is needed.

Critical care of acute ischemic stroke

Stroke is the third leading cause of death and the leading cause of disability in the United States. This article summarizes the critical care of acute ischemic stroke, including conventional and novel therapies. The article provided an overview of the initial management, diagnostic workup, treatment options, and supportive measures that need to be considered in the acute phase of ischemic stroke.

Acute ischemic stroke: overview of recent therapeutic developments

Stroke, a disorder encompassing all cerebrovascular accidents, is a public health problem of immense proportions across the globe. Therapeutic efforts are directed at three aspects: prevention, acute treatment, and rehabilitation. Preventative measures, which in many instances mirror those for cardiovascular disease, can achieve the greatest public health impact. Measures that enhance the recovery of neurologic function and reduce neurologic disability after stroke can also affect a large population of handicapped stroke survivors. In the past 10 years, the greatest changes have occurred in the field of acute stroke treatment. Ultra-early-stage therapies with the potential to dramatically reverse severe neurologic deficits, or halt their progression, have caused a restructuring of the emergency care of neurologic patients. The parallels with the evolution of emergency treatment of acute coronary syndromes after 1970 are striking. This review focuses on aspects of stroke therapy that are either just entering, or soon to enter, current practice.

Factors influencing the detection of early CT signs of cerebral ischemia: an internet-based, international multiobserver study

BACKGROUND AND PURPOSE

Early CT signs of cerebral ischemia are subtle. Little is known of which factors influence the detection of infarct signs. We compared neuroradiologists' scan readings with those of other specialists involved in the care of stroke patients.

METHODS

We used the Internet to show 63 CT scans, all acquired <6 hours after stroke and representing different patient ages, times to scanning, stroke severity, and early CT signs of ischemia to physicians involved in stroke care. They completed a structured scan interpretation proforma over the Internet. We compared the detection of early ischemic signs stratified by severity and the effect of prior stroke between different specialties.

RESULTS

Among 207 observers, neuroradiologists saw significantly more of "any early ischemic changes" than did stroke physicians, general radiologists, geriatricians, or neurologists (all P<0.0001), predominantly due to neuroradiologists' greater detection of "mild" hypoattenuation or swelling. Detection of "severe" hypoattenuation or swelling, and hyperattenuated arteries did not differ between specialties. Old infarcts impaired recognition of early ischemic signs. Non-neuroradiologists did not "over-call" signs. Years of scan-reading experience did not account for these differences, but neuroradiologists took, on average, 30 seconds longer to read each scan than did most other specialists (P<0.0001).

CONCLUSIONS

Non-neuroradiologists should realize that they are unlikely to over-call signs, that old infarcts may distract them from seeing early ischemic signs, and read stroke CT scans more slowly, as these factors may help them perform more like neuroradiologists.

Clinical-diffusion mismatch defined by NIHSS and ASPECTS in non-lacunar anterior circulation infarction

OBJECTIVES

Instead of the mismatch in MRI between the perfusion-weighted imaging (PWI) lesion and the smaller diffusion-weighted imaging (DWI) lesion (PWI-DWI mismatch), clinical-DWI mismatch (CDM) has been proposed as a new diagnostic marker of brain tissue at risk of infarction in acute ischemic stroke. The Alberta Stroke Program Early CT Score (ASPECTS) has recently been applied to detect early ischemic change of acute ischemic stroke. The present study applies the CDM concept to DWI data and investigated the utility of the CDM defined by the NIH Stroke Scale (NIHSS) and ASPECTS in patients with non-lacunar anterior circulation infarction.

METHODS

Eighty-seven patients with first ever ischemic stroke within 24 hours of onset with symptoms of non-lacunar anterior circulation infarction with the NIHSS score>or=8 were enrolled. Initial lesion extent was measured by the ASPECTS on DWI within 24 hours, and initial neurological score was measured by the NIHSS. As NIHSS>or=8 has been suggested as a clinical indicator of a large volume of ischemic brain tissue, and the majority of patients with non-lacunar anterior infarction with score of NIHSS<8 had lesions with ASPECTS>or=8 on DWI, so CDM was defined as NIHSS>or=8 and DWI-ASPECTS 8>or=. We divided patients into matched and mismatched patient groups, and compared them with respect to background characteristics, neurological findings, laboratory data, radiological findings and outcome.

RESULTS

There were 35 CDM-positive patients (P group, 40.2%) and 52 CDM-negative patients (N group , 59.8%). P group patients had a higher risk of early neurological deterioration (END) than N group patients (37.1% vs 13.5%, p<0.05), which were always accompanied by lesion growth defined by 2 or more points decrease on ASPECTS (36 to 72 hours after onset on CT). The NIHSS at entry were significantly lower in the P group, but there was no difference in the outcome at three months measured by the modified Rankin Scale. However, CDM was not an independent predictor of END by multiple logistic regression analysis.

CONCLUSIONS

Patients with CDM had high rate of early neurological deterioration and lesion growth. CDM defined as NIHSS>or=8 and DWI-ASPECTS>or=8 can be another marker for detecting patients with tissue at risk of infarction, but more work is needed to clarify whether this CDM method is useful in acute stroke management.

Differential Prognosis of Isolated Cortical Swelling and Hypoattenuation on CT in Acute Stroke

Background and Purpose— The Alberta Stroke Program Early CT Score (ASPECTS) is a validated method of assessing parenchymal ischemic changes, including focal swelling and hypoattenuation. The hypothesis that these signs result from different pathophysiological processes was tested by comparing CT with diffusion and perfusion- weighted MRI.

Methods— MRI and CT were performed, within 2 hours of each other, in 30 ischemic stroke patients <17 hours after symptom onset. Relative apparent diffusion coefficient, relative cerebral blood flow, and relative cerebral blood volume were calculated for individual cortical ASPECTS regions. Regional infarction was assessed on days 3 to 5.

Results— Isolated focal swelling was seen in 25 ASPECTS cortical regions from 6 patients. Cortical hypoattenuation was observed in 25 regions from 11 patients. Median relative apparent diffusion coefficient was significantly lower in hypoattenuated regions (0.84; interquartile range, 0.66 to 0.91) relative to those with focal swelling (0.97; interquartile range, 0.91 to 1.01; P <0.001). Median relative cerebral blood flow in focal swelling regions (81.0%; interquartile range, 70.4 to 93.0) was similar to that of tissue that appeared normal on CT (71.8%; interquartile range, 47.1 to 94.5). In hypoattenuated regions, relative cerebral blood flow was significantly decreased (37.0%; interquartile range, 25.6 to 70.2; P =0.002). Median relative cerebral blood volume was increased (121.1%; interquartile range, 112.0 to 130.3) in focal swelling regions, relative to normal-appearing tissue (94.7%; interquartile range, 62.0 to 114.6; P <0.001), but decreased in hypoattenuated regions (58.9%; interquartile range, 47.5 to 92.7; P =0.012). Infarction occurred in all hypoattenuated regions, but only in 32% of those with focal swelling.

Conclusions— Elevated relative cerebral blood volume and normal relative apparent diffusion coefficient in ASPECTS regions with focal swelling on CT is consistent with penumbral tissue. Isolated focal swelling is not always associated with infarction. These results support removal of focal swelling from the ASPECTS system.

Endovascular management of acute ischemic stroke: advances in patient and treatment selection

Selection of patients for acute-stroke therapy has traditionally been based on rigid time criteria in clinical trials. Recent advances in radiographic imaging have allowed clinicians to estimate brain physiology and thus utilize radiographic parameters to select patients for acute-stroke therapies. Both a better understanding and the quantification methods of salvageable tissue versus irreversibly injured tissue can help guide clinicians to which treatment modality to utilize. The evolution of endovascular techniques to treat acute stroke has resulted in treatment modalities that include mechanical and chemical methods to revascularize occluded cerebral arteries. Prior technical limitations to accessing distal-cerebral arteries have been partially overcome by modifications in technology. Patient and treatment-modality selection can help reduce hemorrhagic complication rates and also potentially increase revascularization rates, which may translate into improved clinical outcomes. We review the recent advances in radiographic imaging that have advanced patient selection in treating acute ischemic stroke and also consider current endovascular treatment options that are available to interventionalists performing these procedures.

Color-coded perfused blood volume imaging using multidetector CT: initial results of whole-brain perfusion analysis in acute cerebral ischemia

Computed tomography (CT) is still the primary imaging modality following acute stroke. To evaluate a prototype of software for the calculation of color-coded whole-brain perfused blood volume (PBV) images from CT angiography (CTA) and nonenhanced CT (NECT) scans, we studied 14 patients with suspected acute ischemia of the anterior cerebral circulation. PBV calculations were performed retrospectively. The detection rate of ischemic changes in the PBV images was compared with NECT. The volume of ischemic changes in PBV was correlated with the infarct volume on follow-up examination taking potential vessel recanalization into account. PBV demonstrated ischemic changes in 12/12 patients with proven infarction and was superior to NECT (8/12) in the detection of early ischemia. Moreover, PBV demonstrated the best correlation coefficient with the follow-up infarct volume (Pearson's R = 0.957; P = 0.003) for patients with proven recanalization of initially occluded cerebral arteries. In summary, PBV appears to be more accurate in the detection of early infarction compared to NECT and mainly visualizes the irreversibly damaged ischemic tissue.

Site of arterial occlusion identified by transcranial Doppler predicts the response to intravenous thrombolysis for stroke

BACKGROUND AND PURPOSE

The objective of this study was to examine clinical outcomes and recanalization rates in a multicenter cohort of stroke patients receiving intravenous tissue plasminogen activator by site of occlusion localized with bedside transcranial Doppler. Angiographic studies with intraarterial thrombolysis suggest more proximal occlusions carry greater thrombus burden and benefit less from local therapy.

METHODS

Using validated transcranial Doppler criteria for specific arterial occlusion (Thrombolysis in Brain Ischemia flow grades), we compared the rate of dramatic recovery (National Institutes of Health Stroke Scale score < or =2 at 24 hours) and favorable outcomes at 3 months (modified Rankin Scale < or =1) for each occlusion site. We determined the likelihood of recanalization at various occlusion sites and its predictors. Then, stepwise logistic regression was used to determine predictors of complete recanalization.

RESULTS

Three hundred thirty-five patients had a mean age 69+/-13 years and 48.5% were women (median baseline National Institutes of Health Stroke Scale score 16 [range, 3 to 32], mean time to transcranial Doppler 140+/-84 minutes, and mean time to intravenous tissue plasminogen activator 145+/-68 minutes). Distal middle cerebral artery occlusion had an OR of 2 for complete recanalization (50 of 113 [44.2%], 95% CI: 1.1 to 3.1, P=0.005), proximal middle cerebral artery 0.7 (49 of 163 [30%], 95% CI: 0.4 to 1.1, P=0.13), terminal internal carotid artery 0.1 (one of 17 [5.9%], 95% CI: 0.015 to 0.8, P=0.015), tandem cervical internal carotid artery/middle cerebral artery 0.7 (6 of 22 [27%], 95% CI: 0.3 to 1.9, P=0.5), and basilar artery 0.96 (3 of 10 [30%], 95% CI: 0.2 to 4, P=0.9). Prerecombinant tissue plasminogen activator National Institutes of Health Stroke Scale score, systolic blood pressure, glucose, and Thrombolysis in Brain Ischemia flow grade at the occlusion site were the negative independent predictors for complete recanalization in the final model. There were no associations among time to treatment, stroke mechanisms, or recanalization rate. Patients with no flow (Thrombolysis in Brain Ischemia 0) at the occlusion site had less probability of complete recanalization than patients with dampened flow (Thrombolysis in Brain Ischemia 3) (OR(adj): 0.256, 95% CI: 0.11 to 0.595, P=0.002). Continuous transcranial Doppler monitoring (exposure to ultrasound) was a positive predictor for complete recanalization (OR(adj): 3.02, 95% CI: 1.396 to 6.514, P=0.005). National Institutes of Health Stroke Scale score < or =2 at 24 hours was achieved in 66 of 305 patients (22%): distal middle cerebral artery 33% (35 of 107), tandem cervical internal carotid artery/middle cerebral artery 24% (5 of 21), proximal middle cerebral artery 16% (24 of 155), basilar artery 25% (2 of 8), and none of the patients with terminal internal carotid artery had dramatic recovery (0%, n=14; P=0.003). Modified Rankin Scale score < or =1 was achieved in 90 of 260 patients (35%): distal middle cerebral artery 52% (50 of 96), proximal middle cerebral artery 25% (33 of 131), tandem cervical internal carotid artery/middle cerebral artery 21% (3 of 14), terminal internal carotid artery 18% (2 of 11), and basilar artery 25% (2 of 8) (P<0.001). Patients with distal middle cerebral artery occlusion were twice as likely to have a good long-term outcome as patients with proximal middle cerebral artery (OR: 2.1, 95% CI: 1.1 to 4, P=0.025).

CONCLUSIONS

Clinical response to thrombolysis is influenced by the site of occlusion. Patients with no detectable residual flow signals as well as those with terminal internal carotid artery occlusions are least likely to respond early or long term.

The NeuroGrid stroke exemplar clinical trial protocol

RATIONALE

Trials of new treatments for neurological disorders like stroke require imaging as part of the patient assessment, but need to be large enough to obtain reliable results if treatment effects are likely to be modest. However, multicentre trials use many different scanners in different hospitals and present complex problems for image data collection, interpretation and analysis and long-term secure archiving.

AIMS

NeuroGrid aims to develop and test grid technologies for collecting, analysing and interpreting, and secure archiving of neuroimaging data for large multicentre trials in common neurological and psychiatric disorders.

DESIGN

A 3-year multicentre consortium of clinicians, neuroimaging centres and e-scientists are designing a Grid storage network, mechanisms for uploading, curating and retrieving image and metadata, combining image data from different scanners and an analysis tool box. Three clinical exemplars--stroke, dementia and psychosis--provide the data and 'real-world' clinical trial applications, and a set of specific and typical problems encountered with image data in multicentre trials for NeuroGrid to address. The stroke exemplar is using image data from two multicentre stroke trials: Third International Stroke Trial and Efficacy of Nitric Oxide in Stroke.

OUTCOMES

The final product is intended to appear as an integrated capability consisting of services, both database and analyses, accessed through simple portals. These will include image submission, automated scan quality control, appropriate metadata linkage, streamlined image review and coding tools and long-term secure storage for future multicentre stroke trials.

Mechanical thrombectomy with snare in patients with acute ischemic stroke

INTRODUCTION

We evaluated the efficacy and safety of thrombus extraction using a microsnare in patients with acute ischemic stroke (AIS).

METHODS

This was a prospective, observational, cohort study in which consecutive patients with AIS (<6 hours of ischemia for anterior circulation and <24 hours for posterior circulation) who had been previously excluded from intravenous tissue plasminogen activator (tPA) thrombolysis were included and followed-up for 3 months. Mechanical embolectomy with a microsnare of 2-4 mm was undertaken as the first treatment. Low-dose intraarterial thrombolysis or angioplasty was used if needed. TIMI grade and modified Rankin stroke scale (mRSS) score were used to evaluate vessel recanalization and clinical efficacy, respectively.

RESULTS

Nine patients (mean age 55 years, range 17-69 years) were included. Their basal mean NIHSS score was 16 (range 12-24). In seven out of the nine patients (77.8%) the clot was removed, giving a TIMI grade of 3 in four patients and TIMI grade 2 in three patients. Occlusion sites were: middle cerebral artery (four), basilar artery (two) and anterior cerebral artery plus middle cerebral artery (one). The mean time for recanalization from the start of the procedure was 50 min (range 50-75 min). At 3 months, the mRSS score was 0 in two patients and 3-4 in three patients (two patients died).

CONCLUSION

According to our results, the microsnare is a safe procedure for mechanical thrombectomy with a good recanalization rate. Further studies are required to determine the role of the microsnare in the treatment of AIS.

First experience with intravenous thrombolysis in ischemic stroke in Serbia

Introduction Systemic thrombolytic therapy in the first three hours of acute ischemic stroke (IS) significantly improves its outcome. This therapy was approved for treatment in USA in 1997, and in most European countries in 2002. First intravenous thrombolysis of IS in Serbia was carried out in February 2006. Objective We present our preliminary experience with intravenous thrombolysis in treating patients with acute IS and compare it with the results of other clinical studies. Method All patients with IS treated with intravenous thrombolysis in our department were included in the study. The time of stroke onset, first neurological exam, time of CT exam and beginning of therapy were recorded. The early CT signs of ischemia were graded by the ASPECTS score. Neurological deficit was assessed with NIHSS score and functional outcome with modified Rankin Scale (mRS). Results During the eight-month period intravenous thrombolysis was given to 12 patients with acute IS, aged 18 to 66 years, of whom 75% were younger than 55 years. Median time from symptom onset to hospital door was 57.5 minutes, median time door-to-CT was 32.5 minutes, and the time from symptom onset to treatment was 155 minutes. Early CT signs of ischemia were present in 10 patients with median ASPECTS score 9. Median initial NIHSS score was 16.5 with its decline during the first 24 hours for at least 5 points in 58% of patients. Symptomatic intracerebral haemorrhage was present in one patient. After 30 days of follow-up 42% of patients had favourable outcome (mRS?1). In only 2 patients the outcome was poor (mRS 4-5). One patient died with signs of cardiac failure. Conclusion Despite a small number of patients with short time of follow up, these results with thrombolysis in acute IS were found to be consistent with other authors? reports. Uniqueness of our series of patients who received thrombolysis as compared to other studies was their very young age.

Early Recanalization After Intravenous Administration of Recombinant Tissue Plasminogen Activator as Assessed by Pre- and Post-Thrombolytic Angiography in Acute Ischemic Stroke Patients

BACKGROUND AND PURPOSE

Recanalization rates after the intravenous (IV) recombinant tissue plasminogen activator (rt-PA) treatment have been poorly studied in acute stroke.

METHODS

CT angiography was performed before IV rt-PA in all patients and digital subtraction angiography was undertaken for intra-arterial thrombolysis in cases of no improvement after rt-PA infusion.

RESULTS

Forty-five patients were treated with IV rt-PA. Initial CT angiography showed relevant arterial occlusions in 35 patients. Recanalization after rt-PA therapy was demonstrated by digital subtraction angiography in 7 of the 31 patients with the occlusion on initial CT angiography: 2/16 in the internal carotid or proximal middle cerebral artery, 3/11 in the distal middle cerebral artery and 2/4 in the basilar artery occlusion.

CONCLUSIONS

The early recanalization rate after IV rt-PA use was very low in cases with large proximal arterial occlusions. CT angiography before IV rt-PA may be useful for the prediction of its efficacy.

Elevated Troponin Levels Are Associated with Sympathoadrenal Activation in Acute Ischaemic Stroke

BACKGROUND

It has been hypothesised that elevated serum troponin levels in acute stroke are due to myocardial damage caused by sympathoadrenal activation, which, in turn, may be due particularly to insular damage. We aimed to determine the factors associated with troponin elevation in ischaemic stroke and the prognostic value of this finding.

METHODS

We studied 222 consecutive acute ischaemic stroke admissions. Serum troponin I and catecholamines were measured. Ischaemic damage on brain computed tomography (CT) scan was graded using the Alberta Stroke Program Early CT Score (ASPECTS). Electrocardiograms were classified using the Minnesota Code and the European Society of Cardiology/American College of Cardiology criteria for acute myocardial infarction. The Rankin scale was recorded at 30 days.

RESULTS

Forty-five patients (20%) had troponin I >0.2 microg/l. These troponin-positive patients had higher epinephrine levels (median 0.27 vs. 0.17 nmol/l; p = 0.0002) and were more likely to have electrocardiograms coded as definite or possible acute myocardial infarction (odds ratio 3.35; 95% CI 1.26-8.93), compared with those with troponin < or = 0.2 microg/l, in univariate analysis. There were no significant associations between troponin I score and ASPECTS or insular damage on brain CT. In logistic regression analyses, elevated troponin was significantly associated with age, elevated serum creatinine and epinephrine; however, increased troponin was not an independent predictor of death or dependency (Rankin >2) at 30 days.

CONCLUSIONS

Raised troponin I is associated with elevation of circulating epinephrine in acute ischaemic stroke. Activation of the sympathoadrenal system may be an important contributor to myocardial damage in these patients. Increased troponin is not associated with insular damage and does not independently predict poor outcome.

EFNS guideline on neuroimaging in acute stroke. Report of an EFNS task force

Neuroimaging techniques are necessary for the evaluation of stroke, one of the leading causes of death and neurological impairment in developed countries. The multiplicity of techniques available has increased the complexity of decision making for physicians. We performed a comprehensive review of the literature in English for the period 1965-2005 and critically assessed the relevant publications. The members of the panel reviewed and corrected an initial draft, until a consensus was reached on recommendations stratified according to the European Federation of Neurological Societies (EFNS) criteria. Non-contrast computed tomography (CT) scan is the established imaging procedure for the initial evaluation of stroke patients. However, magnetic resonance imaging (MRI) has a higher sensitivity than CT for the demonstration of infarcted or ischemic areas and depicts well acute and chronic intracerebral hemorrhage. Perfusion and diffusion MRI together with MR angiography (MRA) are very helpful for the acute evaluation of patients with ischemic stroke. MRI and MRA are the recommended techniques for screening cerebral aneurysms and for the diagnosis of cerebral venous thrombosis and arterial dissection. For the non-invasive study of extracranial vessels, MRA is less portable and more expensive than ultrasonography but it has higher sensitivity and specificity for carotid stenosis. Transcranial Doppler is very useful for monitoring arterial reperfusion after thrombolysis, for the diagnosis of intracranial stenosis and of right-to-left shunts, and for monitoring vasospasm after subarachnoid hemorrhage. Currently, single photon emission computed tomography and positron emission tomography have a more limited role in the evaluation of the acute stroke patient.

Translational vehicles for neuroprotection

This review will analyse particular criteria in the analysis of stroke diagnosis and treatment, which are pivotal for the successful translation of experimental data from the laboratory to humans.