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

CT Angiographic Source Images Predict Outcome and Final Infarct Volume Better Than Noncontrast CT in Proximal Vascular Occlusions

Background and Purpose—

Alberta Stroke Programme Early CT Score (ASPECTS) is widely used for assessment of early ischemic changes in acute stroke. We hypothesized that CT angiography source image (CTA-SI) ASPECTS correlates better with baseline National Institutes of Health Stroke Scale score, final ASPECTS and neurological outcomes when compared with noncontrast CT ASPECTS.

Methods—

We studied patients presenting with acute ischemic stroke and identified proximal arterial occlusions (internal carotid artery, middle cerebral artery M1, and proximal middle cerebral artery M2) from the Calgary CT Angiography database. CT scans were independently read by 3 observers for baseline noncontrast CT ASPECTS, CT angiography source image ASPECTS, and follow-up ASPECTS. Details of demographics and risk factors were noted. A modified Rankin Scale score ≤2 at 3 months was considered a favorable outcome.

Results—

We identified 261 patients with proximal occlusions for analysis. We found a better correlation between CT angiography source image ASPECTS and follow-up ASPECTS (Spearman correlation coefficient r =0.65; 95% CI, 0.58 to 0.72; P <0.001) than between noncontrast CT ASPECTS and follow-up CT ASPECTS ( r =0.46; 95% CI, 0.36 to 0.55; P <0.001). CT angiography source image ASPECTS correlated better with baseline National Institutes of Health Stroke Scale and 24-hour National Institutes of Health Stroke Scale when compared with noncontrast CT ASPECTS ( P <0.001). In an adjusted model including both CT angiography source image ASPECTS and noncontrast CT ASPECTS, CT angiography source image ASPECTS was associated with good outcome (OR, 2.30; 95%, CI, 1.16 to 4.53), whereas noncontrast CT ASPECTS was not (OR, 1.54; 95% CI, 0.84 to 2.82). Among imaging parameters, CT angiography source image ASPECTS was the only independent predictor of good outcome (OR, 2.29; 95% CI, 1.16 to 4.53).

Conclusions—

CT angiography source image ASPECTS correlates better with baseline stroke severity, is a better predictor of final infarct extension, and independently predicts neurological outcome than noncontrast CT ASPECTS.

Risk of later seizure after perinatal arterial ischemic stroke: a prospective cohort study

OBJECTIVE

Although acute seizures are common among neonates with arterial ischemic stroke (AIS), the incidence of subsequent seizures is unknown. The goals of this study were to determine the incidence of seizures following hospital discharge after perinatal acute AIS, and to assess lesion characteristics associated with later seizure occurrence.

METHODS

Neonates with confirmed acute AIS on MRI were identified through a prospective stroke registry. Clinic visits and telephone follow-up identified occurrence of seizures after hospital discharge. MRI scans were graded for size and characteristics of infarct, and associations with seizures after stroke were analyzed.

RESULTS

At a mean (SD) follow-up of 31.3 (16.1) months, 11 of 46 (23.9%) patients with perinatal AIS had at least 1 seizure. Five patients had a single episode of seizure, and 6 developed epilepsy. The Kaplan-Meier probability of remaining seizure-free at 3 years was 73%. Stroke size on MRI was significantly associated with development of later seizures, with an incidence rate of later seizures 6.2 times higher among those with larger stroke size.

CONCLUSIONS

Seizures occurred in <25% of patients during initial follow-up after perinatal AIS. Of those with seizures, nearly half had a single episode of seizure and not early epilepsy. Larger stroke size was associated with higher risk of seizure. These data suggest that prolonged treatment with anticonvulsant agents may not be indicated for seizure prophylaxis after perinatal AIS. These findings may help guide clinicians in counseling families and could form the basis for much-needed future research in this area.

Computed tomography perfusion–based selection of patients for endovascular recanalization

Intravenous and intraarterial recombinant tissue plasminogen activator remains underutilized in the treatment of acute ischemic stroke, largely due to strict adherence to the concept of the therapeutic time window for administration. Recent efforts to expand the number of patients eligible for thrombolysis have been mirrored by an evolution in endovascular recanalization technology and techniques. As a result, there is a growing need to establish efficient and reliable means by which to select candidates for endovascular intervention beyond the traditional criteria of time from symptom onset. Perfusion imaging techniques, particularly CT perfusion used in combination with CT angiography, represent an increasingly recognized means by which to identify those patients who stand to benefit most from endovascular recanalization. Additionally, CT perfusion and CT angiography appear to provide sufficient data by which to exclude patients in whom there is little chance of neurological recovery or a substantial risk of postprocedure symptomatic intracranial hemorrhage. The authors review the current literature as it pertains to the limitations of time-based selection of patients for intervention, the increasing utilization of endovascular therapy, and the development of a CT perfusion-based selection of acute stroke patients for endovascular recanalization. Future endeavors must prospectively evaluate the utility and safety of CT perfusion-based selection of candidates for endovascular intervention.

Usefulness of MRA-DWI mismatch in neuroendovascular therapy for acute cerebral infarction

BACKGROUND

This study evaluated the usefulness of MR angiography (MRA)-diffusion-weighted imaging (DWI) mismatch in neuroendovascular therapy over 3 h after onset of acute cerebral infarction.

METHODS

The subjects were 14 cases (age, 73 ± 8.4 years) who had an anterior circulation deficit on DWI/MRA on arrival and underwent neuroendovascular therapy over 3 h after onset. MRA-DWI mismatch (MDM) (+) was defined as 'major artery lesion (+) and diffusion-weighted image-Alberta Stroke Program Early CT Score (DWI-ASPECTS) ≥6'; MDM (-) was defined as 'major artery lesion (+) and DWI-ASPECTS <6'.

RESULTS

Reperfusion was achieved in nine of 14 patients (64%) undergoing neuroendovascular therapy. Within the reperfusion group, in the five MDM (+) patients and the four MDM (-) patients, the outcome was a favorable clinical response in the MDM (+) group. The modified Rankin Scale (mRS) scores after 90 days were 0-2 in 3 (60%) and 3-6 in 2 (40%) of the MDM (+) group patients and 0-2 in 0 (0%) and 3-6 in 4 (100%) of the MDM (-) group patients. In the MDM (+) group, a good outcome was achieved. However, the number of cases was small, so this was not a significant difference. Within the non-reperfusion group, in the three MDM (+) patients and the two MDM (-) patients, the mRS scores after 90 days were 0-2 in 1 (33%) and 3-6 in 2 (67%) of the MDM (+) group patients and 0-2 in 0 (0%) and 3-6 in 2 (100%) of the MDM (-) group patients. In both groups, the outcome was poor.

CONCLUSIONS

With neuroendovascular therapy, a good outcome with reperfusion was achieved in the MDM (+) group compared to the MDM (-) group. This suggests that the presence or absence of MDM may be useful in determining prognosis after reperfusion.

Mechanical thrombectomy with a self-expanding retrievable intracranial stent (Solitaire AB): experience in 26 patients with acute cerebral artery occlusion

BACKGROUND AND PURPOSE

Patients with stroke unsuitable for IV thrombolysis may be considered for endovascular revascularization, particularly when baseline imaging suggests proximal cerebral vessel occlusion associated with minimal established infarction. This retrospective review describes the use of a self-expanding retrievable intracranial stent (Solitaire AB) for thrombectomy in acute ischemic stroke.

MATERIALS AND METHODS

Twenty-six consecutive patients with stroke treated endovascularly by using the Solitaire stent were identified, followed by detailed review of data extracted from their imaging and clinical records.

RESULTS

Recanalization (TIMI grade ≥2) was achieved with Solitaire thrombectomy as the single treatment technique in 16 patients and in combination with urokinase or the Penumbra device in 9 of the remaining 10 patients. Two patients had symptomatic intracranial hemorrhage. A favorable clinical outcome (mRS score of ≤2) was seen in 3 of 5 patients with MCA occlusion, 6 of 11 (55%) patients with ICA occlusion, and 2 of 10 patients with BA occlusion.

CONCLUSIONS

Mechanical thrombectomy by using the Solitaire stent appears to be safe and is capable of achieving a high rate of recanalization and favorable clinical outcomes in patients presenting with proximal cerebral vessel occlusion.

A smartphone client-server teleradiology system for primary diagnosis of acute stroke

Background

Recent advances in the treatment of acute ischemic stroke have made rapid acquisition, visualization, and interpretation of images a key factor for positive patient outcomes. We have developed a new teleradiology system based on a client-server architecture that enables rapid access to interactive advanced 2-D and 3-D visualization on a current generation smartphone device (Apple iPhone or iPod Touch, or an Android phone) without requiring patient image data to be stored on the device. Instead, a server loads and renders the patient images, then transmits a rendered frame to the remote device.

Objective

Our objective was to determine if a new smartphone client-server teleradiology system is capable of providing accuracies and interpretation times sufficient for diagnosis of acute stroke.

Methods

This was a retrospective study. We obtained 120 recent consecutive noncontrast computed tomography (NCCT) brain scans and 70 computed tomography angiogram (CTA) head scans from the Calgary Stroke Program database. Scans were read by two neuroradiologists, one on a medical diagnostic workstation and an iPod or iPhone (hereafter referred to as an iOS device) and the other only on an iOS device. NCCT brain scans were evaluated for early signs of infarction, which includes early parenchymal ischemic changes and dense vessel sign, and to exclude acute intraparenchymal hemorrhage and stroke mimics. CTA brain scans were evaluated for any intracranial vessel occlusion. The interpretations made on an iOS device were compared with those made at a workstation. The total interpretation times were recorded for both platforms. Interrater agreement was assessed. True positives, true negatives, false positives, and false negatives were obtained, and sensitivity, specificity, and accuracy of detecting the abnormalities on the iOS device were computed.

Results

The sensitivity, specificity, and accuracy of detecting intraparenchymal hemorrhage were 100% using the iOS device with a perfect interrater agreement (kappa = 1). The sensitivity, specificity, and accuracy of detecting acute parenchymal ischemic change were 94.1%, 100%, and 98.09% respectively for reader 1 and 97.05%, 100%, and 99.04% for reader 2 with nearly perfect interrater agreement (kappa = .8). The sensitivity, specificity, and accuracy of detecting dense vessel sign were 100%, 95.4%, and 96.19% respectively for reader 1 and 72.2%, 100%, and 95.23% for reader 2 using the iOS device with a good interrater agreement (kappa = .69). The sensitivity, specificity, and accuracy of detecting vessel occlusion on CT angiography scans were 94.4%, 100%, and 98.46% respectively for both readers using the iOS device, with perfect interrater agreement (kappa = 1). No significant difference (P < .05) was noted in the interpretation time between the workstation and iOS device.

Conclusion

The smartphone client-server teleradiology system appears promising and may have the potential to allow urgent management decisions in acute stroke. However, this study was retrospective, involved relatively few patient studies, and only two readers. Generalizing conclusions about its clinical utility, especially in other diagnostic use cases, should not be made until additional studies are performed.

Final 2 year results of the vascular imaging of acute stroke for identifying predictors of clinical outcome and recurrent ischemic eveNts (VISION) study

Among patients with ischemic stroke, little attention has been paid to differentiation between stroke progression and recurrence. We assessed the role of MR imaging in predicting stroke progression, recurrent stroke, and death within 2 years of symptom onset.

METHODS

Ischemic stroke or TIA patients were prospectively enrolled. They were examined within 12 hours and had a stroke MR completed within 24 hours of symptom onset. Patients were closely followed neurologically and examined if there was any deterioration in neurological status. Relationships between baseline clinical and imaging factors and outcomes were assessed. We also examined whether baseline stroke/TIA severity (NIHSS 0-5 versus NIHSS > 5) modified these relationships.

RESULTS

A total of 334 patients were enrolled. The overall rates of progression, 2-year recurrence, and 2-year death were 8.7%, 8.0%, and 6.6%, respectively. Event rates were similar among patients with mild compared to more severe strokes: 8.3% versus 9.5% (p = 0.73) for progression, and 7.3% versus 9.9% (p = 0.59) for recurrence. The effect of baseline glucose > 8 mmol/l was consistent in predicting stroke progression, recurrent stroke and death, regardless of baseline stroke severity. In multivariable analyses, DWI lesion and intracranial occlusion predicted stroke progression only in the minor stroke/TIA group; symptomatic Internal Carotid Artery (ICA) stenosis predicted stroke recurrence only in the minor stroke/TIA group.

CONCLUSIONS

In a prospective study with early assessment and imaging we have found that stroke progression is different than stroke recurrence. Different imaging factors predict stroke progression versus stroke recurrence. Baseline hyperglycemia, a potentially modifiable factor, consistently predicted all three outcomes (stroke progression, recurrent stroke or death) regardless of baseline stroke severity.

Correlation between CT and diffusion-weighted imaging of acute cerebral ischemia in a rat model

BACKGROUND AND PURPOSE

The quantitative temporal relationship between changes in CT attenuation, ADC value, and DWI signal intensity of acute ischemic tissue has not yet been determined in an animal model. This study was performed to determine the temporal relationship between CT attenuation, ADC value, and DWI signal intensity in acute cerebral ischemia.

MATERIALS AND METHODS

CT and DWI were performed at 1, 3, 5, 7, and 9 hours after left MCA occlusion in 11 rats. Mean values for CT attenuation, ADC, and DWI signal intensity were determined for the ischemic hemisphere and contralateral normal hemisphere. Temporal changes in each mean value and the relationship between CT attenuation and ADC value and DWI signal intensity were evaluated.

RESULTS

The decrease of CT attenuation and the increase of DWI signal intensity occurred gradually after MCA occlusion, while ADC value decreased rapidly at 1 hour. Although correlation was significant between time and rCT or rDWI (P<.01, respectively), no correlation between time and rADC was found (P=.33). There was a significant linear correlation between rCT and rDWI (r=0.497, P<.01), but no significant correlation between rCT and rADC (P=.509) was found.

CONCLUSIONS

The temporal change in CT attenuation was different from that in ADC value with no significant linear correlation between CT attenuation and ADC value for acute cerebral ischemia. However, rCT and rDWI showed a modest correlation.

Thrombolysis in acute ischaemic stroke: an update

Stroke is a major cause of mortality and morbidity, and thrombolysis has served as a catalyst for major changes in the management of acute ischaemic stroke. Intravenous alteplase (recombinant tissue plasminogen activator) is the only approved thrombolytic agent at present indicated for acute ischaemic stoke. While the licensed time window extends to 3h from symptom onset, recent data suggest that the trial window can be extended up to 4.5 h with overall benefit. Nonetheless, 'time is brain' and every effort must be made to reduce the time delay to thrombolysis. Intracranial haemorrhage is the major complication associated with thrombolysis, and key factors increasing risk of haemorrhage include increasing age, high blood pressure, diabetes and stroke severity. Currently, there is no direct evidence to support thrombolysis in patients >80 years of age, with a few case series indicating no overt harm. Identification of viable penumbra based on computed tomography/magnetic resonance imaging may allow future extension of the time window. Adjuvant transcranial Doppler ultrasound has the potential to improve reperfusion rates. While intra-arterial thrombolysis has been in vogue for a few decades, there is no clear advantage over intravenous thrombolysis. The evidence base for thrombolysis in specific situations (e.g. dissection, pregnancy) is inadequate, and individualized decisions are needed, with a clear indication to the patient/carer about the lack of direct evidence, and the risk-benefit balance. Patient-friendly information leaflets may facilitate the process of consent for thrombolysis. This article summarizes the recent advances in thrombolysis for acute ischaemic stroke. Key questions faced by clinicians during the decision-making process are answered based on the evidence available.

Perfusion-weighted map and perfused blood volume in comparison with CT angiography source imaging in acute ischemic stroke different sides of the same coin?

RATIONALE AND OBJECTIVES

Computed tomography angiography source imaging (CTA-SI) in acute ischemic stroke improves detection rate and estimation of extent of cerebral infarction. This study compared the new components color-coded perfusion weighted map (PWM) and color-coded perfused blood volume (PBV) derived from CTA data with CTA-SI for the visualization of cerebral infarction.

MATERIALS AND METHODS

Fifty patients (women = 30; mean age = 74.9 ± 13.3 years) underwent nonenhanced computed tomography and CTA for suspected acute ischemic stroke. PWM, PBV, and CTA-SI were reconstructed with identical slice thickness of 1.0 mm with commercial software. Extent of infarction was measured using the Alberta Stroke Program Early Computed Tomography Score (ASPECTS). For statistical analysis, Spearman's R correlation and paired-samples t-test was used. P < .05 was considered significant.

RESULTS

PBV had superior sensitivity for detection of cerebral infarction with 0.88 compared to PWM and CTA-SI with 0.79 and 0.76, respectively. The accuracy of correct diagnosis was superior for PBV with 0.82 compared to PWM and CTA-SI with 0.76, respectively. ASPECTS of PWM and PBV showed strong correlation with CTA-SI with r = 0.903 (P < .001) and r = 0.866 (P < .001), respectively. Mean ASPECTS of CTA-SI (6.24 ± 3.62) revealed no significant difference with PWM (6.26 ± 3.45), but a significant difference with PBV (5.62 ± 3.41; P < .02).

CONCLUSIONS

PWM was equal to CTA-SI in detection of cerebral infarction and estimation of extent of cerebral ischemia. Although PBV was superior to CTA-SI in detection of cerebral infarction, PBV seems to overestimate the extent of critical cerebral ischemia. Therefore, CTA-SI information is not identical to PBV and further clinical evaluation is mandatory.

Thrombolysis as a factor associated with favorable outcomes in patients with unclear-onset stroke

BACKGROUND AND PURPOSE

Clinical and radiological features of patients with unclear-onset stroke do not differ significantly from those with known-onset stroke. There is a lack of evidence for the safety and efficacy of thrombolysis in patients with unclear-onset stroke. We sought to provide supportive data on the safety and efficiency of thrombolysis in patients with unclear-onset stroke.

METHODS

We retrospectively identified patients with unclear-onset stroke (<3 h of first found abnormal time) from our stroke registry. We performed following protocols for thrombolysis in patients with unclear-onset stroke; initial conventional CT-based intravenous thrombolysis (IVT), repeat MRI during IVT, and then decision to maintain IVT or to perform combined intra-arterial thrombolysis. In addition, we compared clinical outcomes and safety between thrombolyzed and non-thrombolyzed patients.

RESULTS

A total of 78 patients with unclear-onset stroke were included. Twenty-nine patients underwent thrombolysis. Thrombolysis (OR, 6.842; 95% CI, 1.950-24.004; P = 0.003) and baseline NIHSS (OR, 0.769; 95% CI, 0.645-0.917; P = 0.003) were associated with favorable outcomes at 3 months in multivariate logistic regression analysis. The frequency of hemorrhagic transformation and symptomatic ICH was not significantly different between the thrombolyzed and non-thrombolyzed patients (34.4% vs. 40.7% and 10.3% vs. 8.2%, respectively).

CONCLUSION

The results of this study suggest that thrombolysis in unclear-onset stroke could be independently associated with favorable outcomes at 3 months and that thrombolysis based on repeat imaging appears to be safely applied to patients with unclear-onset stroke.

MR imaging-based localized intra-arterial thrombolysis assisted by mechanical clot disruption for acute ischemic stroke due to middle cerebral artery occlusion

BACKGROUND AND PURPOSE

LIT-MCD is used in our institution for acute stroke due to MCA occlusion, with the goal of reducing symptomatic intracranial hemorrhage by maintaining recanalization of the occluded vessels. The purpose of the study was to investigate the safety and efficacy of LIT-MCD and to identify factors associated with a poor outcome in patients undergoing this procedure.

MATERIALS AND METHODS

LIT-MCD for MCA occlusion was performed in 90 of 1907 consecutive patients with acute stroke admitted to our institution. Radiographic data and clinical outcome were evaluated in the 90 patients, and factors predictive of a poor outcome (3-month mRS score, 3-6) were investigated by multivariate analysis.

RESULTS

Recanalization was achieved in 73 of the 90 patients (81%); symptomatic intracranial hemorrhage occurred in 7 (8%); procedure-related complications, in 9 (10%); and a favorable clinical outcome (3-month mRS score, 0-2), in 48 (53%). A high baseline NIHSS score (≥20), a low preprocedural ASPECTS on MR imaging (≤7), proximal M1 occlusion (in the horizontal segment of the MCA at or proximal to the lenticulostriate arteries), and no recanalization were significant predictors of a poor clinical outcome.

CONCLUSIONS

LIT-MCD is a safe and effective treatment for acute stroke due to MCA occlusion. However, further intervention is needed to improve the outcome of patients with proximal M1 occlusion.

Endovascular therapy for cardiac catheterization associated strokes

BACKGROUND

Stroke is one of the most feared complications after cardiac catheterization. Endovascular treatment combining mechanical and pharmacological therapy has been reported as an effective treatment option in selected patients with acute stroke due to large-vessel occlusion. Little is known about safety and clinical outcome when this approach is utilized in cardiac catheterization associated strokes.

METHODS AND RESULTS

We analyzed clinical and radiological characteristics and outcomes in the endovascular acute stroke treatment databases from two University Hospitals from July 2006 to December 2008 (Cleveland Clinic Foundation) and September 1999 and December 2008 (UPMC Presbyterian hospital), respectively. Of a total of 419 acute stroke interventions, 14 (3.34%) were identified as strokes during or immediately after cardiac catheterization. The mean age was 71 ± 7 years; eight were women (57.1%). Mean National Institute of Health Stroke Scale was 17 (±7.6). Four patients underwent intravenous thrombolysis followed by intraarterial intervention. Median time to treatment was 240 minutes from last time seen normal (range 66-1,365 minutes). Seven patients (50%) had a favorable outcome (modified Rankin Scale [mRS]≤ 2). In-patient mortality was 42%.

CONCLUSION

In acute strokes following cardiac catheterization, multimodal endovascular therapy is safe and feasible and despite a high mortality is associated with a higher than expected rate of favorable outcomes compared to the natural history of the disease. Despite a significant proportion of patients developing symptoms in hospitals where neurointerventions are available, the median time to treatment was longer than expected. Future efforts should focus on faster implementation of recanalization therapies for this form of acute stroke.

Ischemic stroke

The goal of stroke imaging is to appropriately select patients for different types of therapeutic management in order to optimize outcome and minimize potential complications. To accomplish this, the radiologist has to evaluate each case and tailor an imaging protocol to fit the patient's needs and best answer the clinical question. This review outlines the routinely used, current neuroimaging techniques and their role in the evaluation of the acute stroke patient. The ability of computed tomography and magnetic resonance imaging to adequately evaluate the infarcted brain parenchyma, the cerebral vasculature, and the ischemic, but potentially viable tissue, often referred to as the "ischemic penumbra," is compared The authors outline an imaging algorithm that has been employed at their institution, and briefly review endovascular therapies that can be used in specific patients for stroke treatment.

Effect of Baseline CT Scan Appearance and Time to Recanalization on Clinical Outcomes in Endovascular Thrombectomy of Acute Ischemic Strokes

Background and Purpose—

The Penumbra Pivotal Stroke Trial reported a 25% good outcome (modified Rankin scale score ≤2) despite an 81% recanalization rate. We evaluated the association of a favorable initial noncontrast CT and a short time to recanalization in predicting good outcome.

Methods—

Data were from the Penumbra Pivotal Stroke Trial. Baseline scans were evaluated by 2 experienced readers blinded to outcomes using ASPECTS. ASPECTS scores were dichotomized into >7 and ≤7 for primary analysis. Data on degree of recanalization based on thrombolysis in myocardial infarction scores, stroke onset to recanalization, and CT to recanalization times were obtained. Primary outcome was modified Rankin scale score ≤2 at 3 months.

Results—

Median baseline NIHSS was 18 (range, 8–34) and median baseline ASPECTS score was 6 (range, 0–10); 81.2% achieved recanalization (thrombolysis in myocardial infarction, 2–3) and (27.7%) achieved good outcome. Good outcome was significantly higher in the ASPECTS score >7 group when compared to the ASPECTS score ≤7 group (50% vs 15%; RR, 3.3; 95% CI, 1.6–6.8; P =0.0001). No patient with an ASPECTS score ≤4 (n=28) or without recanalization (n=16) had a good outcome. There was an interaction between baseline ASPECTS score (>7 and ≤7) and onset to recanalization time (≤300 minutes and >300 minutes) in predicting good outcome ( P =0.06).

Conclusion—

Patients with baseline CT ASPECTS score ≤4 do not benefit from recanalization. Fast recanalization may benefit patients with evident damage on the CT scan (ASPECTS score >4). Overall, patients benefit the most with early recanalization and a favorable baseline CT scan (ASPECTS score >7).

The Hyperdense Internal Carotid Artery Sign: Prevalence and Prognostic Relevance in Stroke Thrombolysis

Introduction. The hyperdense internal carotid artery sign (HICAS) has been suggested as a common marker of terminal internal carotid artery (ICA) thrombus associated with poor outcomes following thrombolysis. We aimed to investigate the prevalence and prognostic significance of the HICAS in an unselected cohort of patients receiving intravenous thrombolysis. Methods. Prethrombolysis NCCTs of 120 patients were examined for the presence of the HICAS and hyperdense middle cerebral artery sign (HMCAS). A poor outcome was defined as a discharge Barthel score <15 or inpatient death. Results. A HICAS was present in 3 patients (2.5%). Prethrombolysis neurological deficits were significantly more severe in patients with a HICAS (P = 0.019). HICAS was not significantly associated with a poor outcome (P = 0.323). HMCAS was significantly associated with severe prethrombolysis neurological deficits (P = 0.0025) and a poor outcome (P = 0.015). Conclusions. This study suggests that the prevalence of the HICAS may be lower than previously reported. The presence of a HICAS was associated with severe prethrombolysis neurological deficits in keeping with terminal ICA occlusion. The role of the HICAS as a prognostic marker in stroke thrombolysis remains unclear.

The albumin in acute stroke (ALIAS) multicenter clinical trial: safety analysis of part 1 and rationale and design of part 2

BACKGROUND AND PURPOSE

enrollment in the Albumin in Acute Stroke (ALIAS) Trial was suspended in late 2007 due to a safety concern. We present the safety data of that Trial ("Part 1") and the rationale for the design of Part 2.

METHODS

ALIAS Part 1 was designed to assess whether 25% albumin (ALB) started within 5 hours of stroke onset would confer neuroprotection in subjects with acute ischemic stroke and baseline National Institutes of Health Stroke Scale of ≥ 6. Exclusion criteria included recent or current congestive heart failure, myocardial infarction, or cardiac surgery. The study comprised 2 cohorts: subjects who received thrombolysis and those who did not, each with 1:1 randomization to ALB or placebo. The primary outcome was the National Institutes of Health Stroke Scale and modified Rankin Scales at 90 days. The intended sample size was 1800.

RESULTS

four hundred thirty-four subjects were enrolled, and 424 were used in the safety analysis (ALB 207, saline 217). There were 36 deaths within the first 30 days in the ALB group and 21 in the saline group. In contrast, death rates after 30 days were similar by treatment. Large strokes were the predominant cause of early death in both groups. In subjects >83 years of age, 90-day death rates were 2.3-fold higher with ALB than with saline (95% CI, 1.04 to 5.12). Similarly, 90-day deaths in subjects receiving excessive fluids were 2.10-fold greater with ALB than with saline (CI, 1.10 to 3.98).

CONCLUSIONS

The ALIAS Part 2 Trial, which started in early 2009, was modified as follows to enhance safety: upper age limit of 83 years; requirement for normal baseline serum troponin level; restriction of total intravenous fluids in the first 48 hours to ≤ 4200 mL; mandatory diuretic at 12 to 24 hours; and detailed site retraining. Because of insufficient nonthrombolysed subjects (22%) in Part 1, the 2-cohort design was eliminated. The Data Safety Monitoring Board has reviewed the safety data of Part 2 3 times and has approved continuation of the trial.

A large web-based observer reliability study of early ischaemic signs on computed tomography. The Acute Cerebral CT Evaluation of Stroke Study (ACCESS)

BACKGROUND

Early signs of ischaemic stroke on computerised tomography (CT) scanning are subtle but CT is the most widely available diagnostic test for stroke. Scoring methods that code for the extent of brain ischaemia may improve stroke diagnosis and quantification of the impact of ischaemia.

METHODOLOGY AND PRINCIPAL FINDINGS

We showed CT scans from patients with acute ischaemic stroke (n = 32, with different patient characteristics and ischaemia signs) to doctors in stroke-related specialties world-wide over the web. CT scans were shown twice, randomly and blindly. Observers entered their scan readings, including early ischaemic signs by three scoring methods, into the web database. We compared observers' scorings to a reference standard neuroradiologist using area under receiver operator characteristic curve (AUC) analysis, Cronbach's alpha and logistic regression to determine the effect of scales, patient, scan and observer variables on detection of early ischaemic changes. Amongst 258 readers representing 33 nationalities and six specialties, the AUCs comparing readers with the reference standard detection of ischaemic signs were similar for all scales and both occasions. Being a neuroradiologist, slower scan reading, more pronounced ischaemic signs and later time to CT all improved detection of early ischaemic signs and agreement on the rating scales. Scan quality, stroke severity and number of years of training did not affect agreement.

CONCLUSIONS

Large-scale observer reliability studies are possible using web-based tools and inform routine practice. Slower scan reading and use of CT infarct rating scales improve detection of acute ischaemic signs and should be encouraged to improve stroke diagnosis.

Validation Assessment of Risk Scores to Predict Postthrombolysis Intracerebral Haemorrhage

Background

Two clinical risk scores, the Haemorrhage After Thrombolysis and Multicentre Stroke Survey scores, have been proposed to predict the risk of intracerebral haemorrhage following thrombolysis in acute ischaemic stroke.

Aims

To validate Haemorrhage After Thrombolysis and Multicentre Stroke Survey scores as predictors of post-tissue plasminogen activator symptomatic intracerebral haemorrhage and asymptomatic intracerebral haemorrhage in an independent cohort.

Methods

Haemorrhage After Thrombolysis and Multicentre Stroke Survey scores were calculated for the cohort of tissue plasminogen activator-treated patients enrolled in the placebo arms of the SAINT-I and SAINT-II trials. The absolute risk of symptomatic intracerebral haemorrhage and asymptomatic intracerebral haemorrhage associated with each scoring system was determined. The overall predictive value was assessed using c-statistics.

Results

Symptomatic intracerebral haemorrhage occurred in 5·6% of 965 patients treated with tissue plasminogen activator in the SAINT cohorts. The risk of symptomatic intracerebral haemorrhage was modestly greater, with higher Haemorrhage After Thrombolysis scores (0: 4·1%, 1: 4·1%, 2: 8·8%, 3: 12·5%, 4: 0%, 5: no subjects). Similar results were seen with the Multicentre Stroke Survey score (0: 0%, 1: 4·8%, 2: 2·3%, 3: 7·3%, 4: 6·3%). In logistic regression, the Haemorrhage After Thrombolysis score was associated with the risk of symptomatic intracerebral haemorrhage (odds ratio=1·41 per point, 95% confidence interval: 1·05–1·89, P=0·021) and asymptomatic intracerebral haemorrhage (odds ratio=1·59 per point, 95% confidence interval: 1·33–1·92, P<0·001). The Multicentre Stroke Survey score was modestly associated with the risk of symptomatic intracerebral haemorrhage (odds ratio=1·43 per point, 95% confidence interval: 0·95–2·15, P=0·084) and asymptomatic intracerebral haemorrhage (odds ratio=1·63 per point, 95% confidence interval: 1·27–2·08, P<0·001). The c-statistic was 0·59 for predicting symptomatic intracerebral haemorrhage and 0·61 for asymptomatic intracerebral haemorrhage for both the Haemorrhage After Thrombolysis and the Multicentre Stroke Survey scores.

Conclusions

While both the Haemorrhage After Thrombolysis and Multicentre Stroke Survey scores were associated with a risk of symptomatic intracerebral haemorrhage, discriminatory ability was limited.

Recanalization therapy for acute ischemic stroke, part 2: mechanical intra-arterial technologies

Stroke therapy has been revolutionized in the past two decades with the widespread implementation of chemical thrombolysis for acute stroke. However, chemical thrombolysis continues to be limited in its efficacy secondary to relatively short time windows and a high associated risk of hemorrhage. In an attempt to minimize hemorrhagic complications and extend the available therapeutic window, mechanical devices designed specifically for thrombus removal, clot obliteration, and arterial revascularization have experienced a recent surge in development and utilization. As such, chemical thrombolytics now represent only one of many options in acute stroke therapy. These new mechanical devices have extended the potential treatment window and now provide alternatives to patients who do not respond to conventional intravenous thrombolysis. This review will discuss the development of these devices, supporting literature, and the individual strengths that each engenders towards a life-saving therapy for stroke.

Alberta Stroke Program Early CT Score (ASPECTS) in patients with wake-up stroke

One-quarter of ischemic strokes occur during sleep, and affected patients are excluded from thrombolytic therapy because of an unknown time of stroke onset. It has been suggested that early ischemic changes detected on computed tomography (CT) are similar in patients with acute stroke and patients who recently awoke with stroke. We compared head CT scans using the Alberta Stroke Program Early CT Score (ASPECTS) in patients who were likely to suffer their stroke during sleep (awoke group) and a control group of patients with stroke of known onset time. Patients were recruited from a prospectively collected acute stroke database. The awoke group was defined as all ischemic stroke patients who were "last seen normal" more than 4 hours ago, arrived between 4 a.m. and 10 a.m., and underwent head CT within 15 hours of the time last seen normal. The control group was randomly selected from patients who underwent head CT within 4 hours of stroke onset. The ASPECTS evaluations were performed by investigators blinded to patient group and time of onset. A modified Rankin Scale (mRS) score was available in 15 awoke patients and 46 control patients at 90 days after stroke. Twenty-eight awoke patients and 68 control patients had suitable imaging for the ASPECTS. Baseline demographic characteristics and risk factors were similar in the 2 groups. The dichotomized ASPECTS analysis (≤7 vs 8-10) showed no significant differences between the groups. ASPECTS was 8-10 in 89.3% the awoke group and 95.6% in the control group (P=.353). There was a trend toward higher 90-day mRS score (0-1) in the awoke group versus controls (73% vs 45%; P=.079). Initial ASPECTS was similar in patients with wake-up stroke and those with 4 hours of symptoms. This suggests that a subset of wake-up stroke patients might be suitable for thrombolytic therapy.

Residual vessel length on magnetic resonance angiography identifies poor responders to alteplase in acute middle cerebral artery occlusion patients: exploratory analysis of the Japan Alteplase Clinical Trial II

BACKGROUND AND PURPOSE

It remains unknown whether the effects of 0.6 mg/kg alteplase differ with occlusion site of the middle cerebral artery (MCA). We therefore evaluated the effects of 0.6 mg/kg intravenous alteplase in patients with different sites of MCA occlusion.

METHODS

An exploratory analysis was made of 57 patients enrolled in the Japan Alteplase Clinical Trial II (J-ACT II), originally designed to evaluate 0.6 mg/kg alteplase in Japanese patients with unilateral occlusion of the MCA (M1 or M2 portion). The residual vessel length (in mm), determined by pretreatment magnetic resonance angiography, was used to reflect the occluded site. The proportions of patients with valid recanalization (modified Mori grade 2 to 3) at 6 and 24 hours and a modified Rankin Scale (mRS) score of 0 to 1 and of 0 to 2 at 3 months were compared between the groups dichotomized according to length of the residual vessel. Multiple logistic-regression models were generated to elucidate the predictors of valid recanalization, mRS 0 to 1, and mRS 0 to 2.

RESULTS

Receiver operating characteristics analysis revealed that 5 mm was the practical cutoff length for dichotomization. In patients with an M1 length < 5 mm (n = 12), the frequencies of valid recanalization at 6 and 24 hours (16.7% and 25.0%) were significantly lower compared with those (62.1% and 82.8%, respectively) of the 45 patients with a residual M1 length ≥ 5 mm and an M2 occlusion (P = 0.008 for 6 hours, P < 0.001 for 24 hours). The proportions of patients who achieved an mRS of 0 to 1 and an mRS of 0 to 2 were also lower for those with an M1 length < 5 mm (8.3% and 16.7%, respectively) compared with the other group (57.8% and 68.9%, respectively; P = 0.003 for mRS 0 to 1, P = 0.002 for mRS 0 to 2). In logistic-regression models, the site of MCA occlusion (< 5 mm) was a significant predictor of valid recanalization at 6 and 24 hours and of an mRS of 0 to 1 and of mRS of 0 to 2.

CONCLUSIONS

In patients with acute MCA occlusion, a residual vessel length < 5 mm on magnetic resonance angiography can identify poor responders to 0.6 mg/kg alteplase. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00412867.

Usefulness of z-score mapping for quantification of extent of hypoattenuation regions of hyperacute stroke in unenhanced computed tomography: analysis of radiologists' performance

OBJECTIVE

The purpose of this study was to evaluate the usefulness of z-score mapping method on neuroradiologists' performance in quantification of the extent of hypoattenuation regions of hyperacute stroke on unenhanced computed tomographic (CT) images by using the Alberta Stroke Programme Early CT Score system.

METHODS

Twenty-one patients with infarction (<3 hours) were retrospectively selected. Five neuroradiologists interpreted CT images first without and then with z-score maps by using the Alberta Stroke Programme Early CT Score system. Their performances in the quantification of the extent of hypoattenuation were compared.

RESULTS

Average accuracies for the quantification without and with the z-score maps were 82.6% and 86.6%, respectively (P < 0.0001). The average area under the receiver operating characteristic curve for detection of focal hypoattenuation significantly increased from 0.883 to 0.925 (P = 0.01) by use of z-score maps.

CONCLUSIONS

The use of z-score mapping method has the potential to help neuroradiologists quantify the extent of hypoattenuation regions of hyperacute stroke on unenhanced CT images.

Dynamic perfusion-CT assessment of early changes in blood brain barrier permeability of acute ischaemic stroke patients

BACKGROUND AND PURPOSE

Damage to the blood brain barrier (BBB) may lead to haemorrhagic transformation after ischaemic stroke. The purpose of this study was to evaluate the effect of patient characteristics and stroke severity on admission BBB permeability (BBBP) values measured with perfusion-CT (PCT) in acute ischaemic stroke patients.

METHODS

We retrospectively identified 65 patients with proven ischaemic stroke admitted within 12 hours after symptom onset. Patients' charts were reviewed for demographic variables and vascular risk factors. The Patlak's model was applied to calculate BBBP values from the PCT data in the infarct core, penumbra and non-ischaemic tissue in the contralateral hemisphere. Mean BBBP values and their 95% confidence intervals (CI) were calculated in the different tissue types. Effects of demographic variables and risk factors on BBBP were analyzed using a multivariate, generalized estimating equations (GEE) model.

RESULTS

BBBP values in the infarct core (mean [95%CI]: 2.48 [2.16-2.85]) and penumbra (2.48 [2.21-2.79]) were significantly higher than in non-ischaemic tissue (2.12 [1.88-2.39]). Multivariate analysis demonstrated that collateral filling has effect on BBBP. Less elevated BBBP values were associated with more than 50% collateral filling.

CONCLUSIONS

BBBP values are increased in ischaemic brain tissue on the admission PCT scan of acute ischaemic stroke patients. Less abnormally elevated BBBP values were observed in patients with more than 50% collateral filling, possibly explaining why there is a relationship between more collateral filling and a lower incidence of haemorrhagic transformation.

Safety of intravenous fibrinolysis in imaging-confirmed single penetrator artery infarcts

BACKGROUND AND PURPOSE

Hemorrhagic transformation (HT) after fibrinolytic therapy may be less common in patients with acute cerebral ischemia confined to single penetrator artery (SPA) territories than in patients with large artery ischemia. Previous investigations of HT diagnosed small vessel ischemia based on lacunar clinical syndromes, an approach known to yield misdiagnosis in one-third to one-half of cases.

METHODS

Consecutive intravenous tissue plasminogen activator-treated patients in a prospectively maintained hospital registry were analyzed. Patients were classified as having SPA ischemia if they had imaging evidence of: (1) deep location; (2) diameter ≤ 1.5 cm; and (3) distribution in a single penetrator territory, regardless of presenting clinical syndrome. Lacunar clinical syndrome was defined according to the Oxfordshire Community Stroke Project classification.

RESULTS

Among 93 intravenous tissue plasminogen activator-treated patients, mean age was 71.5, 62.4% were female, and median pretreatment National Institutes of Health Stroke Scale score was 14. Single penetrator artery ischemia was imaged in 13 (14.0%) and large artery ischemia was imaged in 75 (80.6%), with no visualized ischemic injury in 5 (5.4%). Lacunar clinical syndromes were present in 23 (24.7%), including 10 with SPA ischemia and 9 with large artery ischemia. No patient with imaging-confirmed SPA infarcts experienced any hemorrhagic transformation, whereas any radiological HT occurred in 29.3% of large artery infarcts (P=0.03). Symptomatic intracerebral hemorrhage occurred in 0% of SPA infarcts vs 4.0% of large artery infarcts.

CONCLUSIONS

HT after lytic therapy in imaging-confirmed SPA infarcts is uncommon. Imaging demonstration of ischemia confined to SPA territory better-identifies this population at low risk for hemorrhagic complications than clinical lacunar syndromes.

The pattern of leptomeningeal collaterals on CT angiography is a strong predictor of long-term functional outcome in stroke patients with large vessel intracranial occlusion

BACKGROUND AND PURPOSE

The role of noninvasive methods in the evaluation of collateral circulation has yet to be defined. We hypothesized that a favorable pattern of leptomeningeal collaterals, as identified by CT angiography, correlates with improved outcomes.

METHODS

Data from a prospective cohort study at 2 university-based hospitals where CT angiography was systematically performed in the acute phase of ischemic stroke were analyzed. Patients with complete occlusion of the intracranial internal carotid artery and/or the middle cerebral artery (M1 or M2 segments) were selected. The leptomeningeal collateral pattern was graded as a 3-category ordinal variable (less, equal, or greater than the unaffected contralateral hemisphere). Univariate and multivariate analyses were performed to define the independent predictors of good outcome at 6 months (modified Rankin Scale score ≤2).

RESULTS

One hundred ninety-six patients were selected. The mean age was 69±17 years and the median National Institute of Health Stroke Scale score was 13 (interquartile range, 6 to 17). In the univariate analysis, age, baseline National Institute of Health Stroke Scale score, prestroke modified Rankin Scale score, Alberta Stroke Programme Early CT score, admission blood glucose, history of hypertension, coronary artery disease, congestive heart failure, atrial fibrillation, site of occlusion, and collateral pattern were predictors of outcome. In the multivariate analysis, age (OR, 0.95; 95% CI, 0.93 to 0.98; P=0.001), baseline National Institute of Health Stroke Scale (OR, 0.75; 0.69 to 0.83; P<0.001), prestroke modified Rankin Scale score (OR, 0.41; 0.22 to 0.76; P=0.01), intravenous recombinant tissue plasminogen activator (OR, 4.92; 1.83 to 13.25; P=0.01), diabetes (OR, 0.31; 0.01 to 0.98; P=0.046), and leptomeningeal collaterals (OR, 1.93; 1.06 to 3.34; P=0.03) were identified as independent predictors of good outcome.

CONCLUSIONS

Consistent with angiographic studies, leptomeningeal collaterals on CT angiography are also a reliable marker of good outcome in ischemic stroke.

Effects of antihypertensive treatment after acute stroke in the Continue or Stop Post-Stroke Antihypertensives Collaborative Study (COSSACS): a prospective, randomised, open, blinded-endpoint trial

BACKGROUND

Up to 50% of patients with acute stroke are taking antihypertensive drugs on hospital admission. However, whether such treatment should be continued during the immediate post-stroke period is unclear. We therefore aimed to assess the efficacy and safety of continuing or stopping pre-existing antihypertensive drugs in patients who had recently had a stroke.

METHODS

The Continue or Stop Post-Stroke Antihypertensives Collaborative Study (COSSACS) was a UK multicentre, prospective, randomised, open, blinded-endpoint trial. Patients were recruited at 49 UK National Institute for Health Research Stroke Research Network centres from January 1, 2003, to March 31, 2009. Patients aged over 18 years who were taking antihypertensive drugs were enrolled within 48 h of stroke and the last dose of antihypertensive drug. Patients were randomly assigned (1:1) by secure internet central randomisation to either continue or stop pre-existing antihypertensive drugs for 2 weeks. Patients and clinicians who randomly assigned patients were unmasked to group allocation. Clinicians who assessed 2-week outcomes and 6-month outcomes were masked to group allocation. The primary endpoint was death or dependency at 2 weeks, with dependency defined as a modified Rankin scale score greater than 3 points. Analysis was by intention to treat. This trial is registered with the International Standard Randomised Controlled Trial Register, number ISRCTN89712435.

FINDINGS

763 patients were assigned to continue (n=379) or stop (n=384) pre-existing antihypertensive drugs. 72 of 379 patients in the continue group and 82 of 384 patients in the stop group reached the primary endpoint (relative risk 0.86, 95% CI 0.65-1.14; p=0.3). The difference in systolic blood pressure at 2 weeks between the continue group and the stop group was 13 mm Hg (95% CI 10-17) and the difference in diastolic blood pressure was 8 mm Hg (6-10; difference between groups p<0.0001). No substantial differences were observed between groups in rates of serious adverse events, 6-month mortality, or major cardiovascular events.

INTERPRETATION

Continuation of antihypertensive drugs did not reduce 2-week death or dependency, cardiovascular event rate, or mortality at 6 months. Lower blood pressure levels in those who continued antihypertensive treatment after acute mild stroke were not associated with an increase in adverse events. These neutral results might be because COSSACS was underpowered owing to early termination of the trial, and support the continuation of ongoing research trials.

FUNDING

The Health Foundation and The Stroke Association.

A Comparison of Computed Tomography Perfusion-Guided and Time-Guided Endovascular Treatments for Patients With Acute Ischemic Stroke

Background and Purpose— The role of CT perfusion (CT-P) imaging for the selection of patients with acute ischemic stroke who may benefit from endovascular treatment is not defined. The objective of this study was to determine whether CT-P-guided endovascular treatment improves clinical outcomes compared with standard endovascular treatment based on the time interval between symptom onset and presentation and noncontrast cranial CT imaging.

Methods— A retrospective study was performed comparing the clinical characteristics, complications, and clinical outcomes of patients with acute ischemic stroke who were treated using endovascular modalities based on either CT-P imaging (CT-P-guided) or time interval between symptom onset and presentation and absence of intracerebral hemorrhage or extensive ischemic changes on noncontrast cranial CT scan (time-guided).

Results— The rates of partial and complete recanalization were similar between the CT-P- and time-guided treatment groups (n=61 [88%] versus n=103 [81%]; P =0.52) regardless of whether they received intravenous recombinant tissue plasminogen activator before endovascular treatment. Comparing the CT-P-guided with the time-guided patients, favorable discharge outcome (modified Rankin Scale 0 to 2) was observed in 23 (32%) versus 41 (33%) of the patients, respectively ( P =0.9). In-hospital mortality was observed in 15 (21%) of CT-P- and 29 (23%) of time-guided patients ( P =0.74).

Conclusion— CT-P-guided endovascular treatment did not increase the rate of short-term favorable outcomes among patients with acute ischemic stroke. Prospective studies are required to validate the CT-P criteria and protocols currently in use before incorporating CT-P as a routine modality for patient selection for endovascular treatment.

Hyperdense middle cerebral artery sign is an ominous prognostic marker despite optimal workflow

OBJECTIVES

To evaluate the association between the hyperdense middle cerebral artery sign (HMCAS) and the functional outcome on one hand, and different predictors such as the National Institutes of Health Stroke Scale (NIHSS), infarct size, ASPECTS Score, intracerebral hemorrhage, and mortality on the other hand.

MATERIAL AND METHODS

Retrospective analysis of 120 patients with MCA-stroke treated with intravenous thrombolysis. We tested the association between HMCAS and NIHSS, infarct volume, ASPECTS, outcome, level of consciousness, different recorded time intervals, and the day/time of admission.

RESULTS

Seventy-four percentage of patients treated with thrombolysis developed cerebral infarction. All patients with HMCAS (n = 39) sustained infarction and only 31% showed favorable outcome compared with 62% and 60%, respectively among patients without HMCAS (P < 0.001 and P = 0.002). There was statistically significant association between functional outcome and HMCAS (P = 0.002), infarct volume, NIHSS, and ASPECTS (P < 0.001). The time to treatment was 12 min shorter in patients who developed infarction (P = 0.037). Independent predictors for outcome were NIHSS and the occurrence of cerebral infarction on computed tomography for the whole study population, and infarct volume for patients who sustained cerebral infarction.

CONCLUSIONS

Despite optimal workflow, patients with HMCAS showed poor outcome after intravenous thrombolysis. The results emphasize the urgent need for more effective revascularization therapies and neuroprotective treatment in this subgroup of stroke patients.

Evidence-based guideline: The role of diffusion and perfusion MRI for the diagnosis of acute ischemic stroke: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

OBJECTIVE

To assess the evidence for the use of diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) in the diagnosis of patients with acute ischemic stroke.

METHODS

We systematically analyzed the literature from 1966 to January 2008 to address the diagnostic and prognostic value of DWI and PWI.

RESULTS AND RECOMMENDATIONS

DWI is established as useful and should be considered more useful than noncontrast CT for the diagnosis of acute ischemic stroke within 12 hours of symptom onset. DWI should be performed for the most accurate diagnosis of acute ischemic stroke (Level A); however, the sensitivity of DWI for the diagnosis of ischemic stroke in a general sample of patients with possible acute stroke is not perfect. The diagnostic accuracy of DWI in evaluating cerebral hemorrhage is outside the scope of this guideline. On the basis of Class II and III evidence, baseline DWI volumes probably predict baseline stroke severity in anterior territory stroke (Level B) but possibly do not in vertebrobasilar artery territory stroke (Level C). Baseline DWI lesion volumes probably predict (final) infarct volumes (Level B) and possibly predict early and late clinical outcome measures (Level C). Baseline PWI volumes predict to a lesser degree the baseline stroke severity compared with DWI (Level C). There is insufficient evidence to support or refute the value of PWI in diagnosing acute ischemic stroke (Level U).

The role of CT and MRI in the emergency evaluation of persons with suspected stroke

As a growing number of therapeutic treatment options for acute stroke are being introduced, multimodal acute neuroimaging is assuming a growing role in the initial evaluation and management of patients. Multimodal neuroimaging, using either a CT or MRI approach, can identify the type, location, and severity of the lesion (ischemia or hemorrhage); the status of the cerebral vasculature; the status of cerebral perfusion; and the existence and extent of the ischemic penumbra. Both acute and long-term treatment decisions for stroke patients can then be optimally guided by this information.

Assessment of collateral flow with multi-phasic CT: correlation with diffusion weighted MRI in MCA occlusion

PURPOSE

To correlate collateral flow on multiphasic contrast enhancement computed tomography (CT) and graded ischemic changes on diffusion weighted MR in patients with acute middle cerebral artery (MCA) infarction.

MATERIALS AND METHODS

A retrospective evaluation of diffusion weighted images (DWIs) and three phasic contrast enhanced CT (CECT) was performed on 11 patients with MCA occlusions. The area of ischemic change on DWIs was graded according to the Alberta Stroke Program Early CT Score (ASPECTS) criteria. To evaluate collateral flow on three phasic CECT, we counted the number of contrast enhancing MCA branches distal to the occlusion site at the sylvian fissure from predetermined axial images. The collateral ratios of counted numbers to those at the normal side were calculated at each phase (CR1, CR2, CR3). We then compared collateral ratios from the three phasic CECT with ASPECTS data from DWIs.

RESULTS

Collateral ratios from the three phasic CECT were determined to be CR1 .48 ± .27, CR2 .73 ± .36 and CR3 .72 ± .30. We discovered a correlation between both the CR2 and ASPECTS (r= .675, P= .023) and the CR3 and ASPECTS (r= .664, P= .026).

CONCLUSION

The number of contrast enhancing branches distal to the MCA occlusion, as counted in the sylvian fissure on later phase images of multiphasic CECT, reflects the status of collateral flow, and correlates with ASPECTS on DWIs.

Significance of clinical-diffusion mismatch in hyperacute cerebral infarction

In recent years, patient selection for intravenous tissue plasminogen activator (t-PA) therapy based on clinical-diffusion mismatch (CDM) has been closely examined. We investigated the relationship between prognosis and CDM in patients with hyperacute cerebral infarction within 3 hours of onset and compared CDM with diffusion-perfusion mismatch (DPM). Of 122 patients with hyperacute cerebral infarction who visited the hospital within 3 hours of onset between April 2007 and November 2008, 85 patients with cerebral infarction in the anterior circulation who underwent head magnetic resonance imaging diffusion-weighted imaging (DWI)/magnetic resonance angiography (MRA) (51 men and 34 women; average age, 74 ± 10 years) were enrolled. Seventeen of these patients underwent CT perfusion imaging. CDM-positive cases were those with a National Institute of Health Stroke Scale (NIHSS) score ≥ 8 and a DWI-Alberta Stroke Program Early CT Score (DWI-ASPECTS) ≥ 8; CDM-negative cases were those with an NIHSS score ≥ 8 and an ASPECTS-DWI < 8. The other patients were classified as belonging to the NIHSS score < 8 group. Of the 32 CDM-positive cases, 10 received t-PA infusion. These patients had markedly higher modified Rankin Scale scores 90 days after onset compared with the 22 patients who did not receive t-PA infusion. The 8 CDM-positive cases included 4 DPM-positive cases and 4 DPM-negative cases, and a discrepancy was confirmed between CDM and DPM. In all DPM-positive cases, MRA confirmed lesions in major intracranial arteries. CDM may enable more accurate prediction of outcomes in patients with hyperacute cerebral infarction. In addition, the combination of CDM findings and MRA findings (stenosis or occlusion in major intracranial arteries) may be an alternative to DPM for determining the indications for IV t-PA therapy in patients with hyperacute cerebral infarction.

Certainty of stroke diagnosis: incremental benefit with CT perfusion over noncontrast CT and CT angiography

PURPOSE

To systematically evaluate the diagnostic benefits and inter- and intraobserver reliability of an incremental computed tomographic (CT) protocol in the confirmation of clinically suspected stroke, with combined imaging and clinical data as the reference standard.

MATERIALS AND METHODS

Institutional review board approval was obtained, and participants gave informed consent. A total of 191 patients (mean age, 67 years +/- 16 [standard deviation]; 105 men) with strokelike symptoms of no more than 3 hours duration were recruited. Blinded review was performed by four readers with limited stroke imaging experience. Diagnostic confidence was recorded on a five-point scale. Logistic regression analysis was used to calculate the difference between the real and observed diagnoses, adjusting for confidence. Predictive effects of observed diagnostic performance and confidence score were quantified with the entropy r(2) value. Sensitivity, specificity, and confidence intervals were calculated while accounting for multiple reader assessments. Receiver operating characteristic (ROC) analyses, including area under the ROC curve, were conducted for three modalities in combination with confidence score. Inter- and intraobserver agreement was established with the Cohen kappa statistic.

RESULTS

The final diagnosis was infarct in 64% of the patients, transient ischemic attack in 18%, and stroke mimic in 17%. Large-vessel occlusion occurred in 70% of the patients with an infarct. Sensitivity for stroke determination with noncontrast CT, CT angiography, and CT perfusion increased by 12.4% over that with noncontrast CT and CT angiography and by 18.2% over that with only noncontrast CT for a confidence level of 4 or higher. The incremental protocol was more likely to enable confirmation of clinical stroke diagnosis (odds ratio, 13.3) than was noncontrast CT and CT angiography (odds ratio, 6.4) or noncontrast CT alone (odds ratio, 3.3), The area under the ROC curve was 0.67 for the combination of noncontrast CT and confidence score, 0.72 for the combination of CT angiography and confidence score, and 0.81 for the combination of CT perfusion and confidence score. Inter- and intraobserver agreement increased with progressive sequence use.

CONCLUSION

An incremental stroke protocol that includes CT perfusion increases diagnostic performance for stroke diagnosis and inter- and intraobserver agreement.

Clinical outcome and imaging follow-up in acute stroke patients with normal perfusion CT and normal CT angiography

INTRODUCTION

Acute stroke multimodal CT imaging (MMCT: non-enhanced CT, CT angiography, and CT perfusion (CTP)) may show normal results despite persistent clinical stroke. We prospectively evaluated the sensitivity/specificity of MMCT infarct detection and the clinical outcome in patients with normal MMCT findings.

METHODS

From April 2007 to April 2008, all patients with acute hemispheric stroke within 6 h of symptom onset who underwent complete MMCT and MRI follow-up imaging were included. MMCT analysis included occlusion type, early infarct hypodensities (EIH), mean transit time (MTT), and cerebral blood volume (CBV) maps according to Alberta Stroke Program Early CT Score (ASPECTS). Clinical assessment included symptom onset to CT scan (≤3 h/>3 h), the National Institute of Health Stroke Scale score (admission/discharge), and the modified Rankin scale (mRS) 90 days after stroke onset.

RESULTS

One hundred seven were included (mean age, 68.4 years; ≤3 h, n = 84; >3 h, n = 23; intravenous thrombolysis (IVT), n = 51; ≤3 h, n = 40; >3 h, n = 11). In patients with normal MMCT on admission (n = 54), follow-up MRT detected brain infarctions in 23 patients (lacunar strokes, n = 16; infratentorial strokes, n = 4; territorial infarction, n = 3). Sensitivity/specificity/positive predictive value/negative predictive value of any infarct detection was 69.5%/99.8%/99.9%/57.2% and of a any territorial infarct detection was 93.9%/99.9%/99.9%/93.6%, respectively. In univariate regression analysis (time to CT scan, ≤3 h/>3 h; IVT: yes/no; ASPECTS EIH/CBV/MTT, 10/<10), only the evidence of normal CTP (ASPECTS MTT = 10) had a statistically significant impact (p = 0.02) on a good outcome (mRS 0.1).

CONCLUSION

MMCT sensitivity in acute lacunar or infratentorial stroke was poor. But, we found a high specifity and a fairly good sensitivity in territorial infarct detection. In acute stroke patients with normal MMCT findings on admission, a good clinical prognosis can be expected.

[Effects of statin use on intracranial hemorrhage and clinical outcome after intravenous rt-PA for acute ischemic stroke: SAMURAI rt-PA registry]

PURPOSE

We evaluated whether pre- and post-stroke statin use was associated with intracranial hemorrhage (ICH) and clinical outcome at 3 months after intravenous recombinant tissue plasminogen activator (IV rt-PA) for acute ischemic stroke.

METHODS

This study enrolled 600 consecutive patients (72 +/- 12 years, woman 37.2%) who received IV rt-PA at ten stroke centers that participated in the SAMURAI rt-PA Registry from October 2005 to July 2008.

RESULTS

Statins were used prior to stroke in 112% and within 72 h after IV rt-PA in 10.0% of patients. One hundred nineteen patients (19.8%) developed ICH. Pre-stroke statin use was not an independent factor associated with ICH (OR 1.46; 95% CI 0.76-2.81, p = 0.225). Of 535 patients with a premorbid mRS < or = 1, 199 (37.2%) had a favorable clinical outcome at 3 months (mRS < or = 1). Pre-stroke statin use (OR 1.05; 95% CI 0.55-2.01, p = 0.879), as well as post-stroke statin use (OR 1.31; 95% CI 0.66-2.59, p = 0.440), was not an independent predictor of outcome.

CONCLUSIONS

In patients who received IV rt-PA for acute ischemic stroke, statin use did not increase ICH after thrombolysis, nor was it associated with clinical outcome.

Atlas-based topographical scoring for magnetic resonance imaging of acute stroke

BACKGROUND AND PURPOSE

The Alberta Stroke Program Early CT Score (ASPECTS), a 10-point scale, is a clinical tool for assessment of early ischemic changes after stroke based on the location and extent of a visible stroke lesion. It has been extended for use with MR diffusion-weighted imaging. The purpose of this work was to automate a MR topographical score (MR-TS) using a digital atlas to develop an objective tool for large-scale analyses and possibly reduce interrater variability and slice orientation differences.

METHODS

We assessed 30 patients with acute ischemic stroke with a diffusion lesion who provided informed consent. Patients were imaged by CT and MRI within 24 hours of symptom onset. An MR-TS digital atlas was generated using the ASPECTS scoring sheet and anatomic MR data sets. Automated MR topographical scores (auto-MR-TS) were obtained based on the overlap of lesions on apparent diffusion coefficient maps with MR-TS atlas regions. Auto-MR-TS scores were then compared with scores derived manually (man-MR-TS) and with conventional CT ASPECTS scores.

RESULTS

Of the 30 patients, 29 were assessed with auto-MR-TS. Auto-MR-TS was significantly lower than CT ASPECTS (P<0.001), but with a median difference of only 1 point. There was no significant difference between the auto-MR-TS and the man-MR-TS with a median difference of 0 points; 86% of patient scores differed by <or=1 point.

CONCLUSIONS

Auto-MR-TS provides a measure of stroke severity in an automated fashion and facilitates more objective, sensitive, and potentially more complex ASPECTS-based scoring.

Initial experience in using continuous arterial spin-labeled MR imaging for early detection of Alzheimer disease

BACKGROUND AND PURPOSE

MR imaging of the brain has significant potential in the early detection of neurodegenerative disorders such as AD. The purpose of this work was to determine if perfusion MR imaging can be used to separate AD from normal cognition in individual subjects. We investigated the diagnostic utility of perfusion MR imaging for early detection of AD compared with structural imaging.

MATERIALS AND METHODS

Data were analyzed from 32 participants in the institutional review board-approved CHS-CS: 19 cognitively healthy individuals and 13 with clinically adjudicated AD. All subjects underwent structural T1-weighted SGPR and CASL MR imaging. Four readers with varying experience separately rated each CASL and SPGR scan finding as normal or abnormal on the basis of standardized qualitative diagnostic criteria for observed perfusion abnormalities on CASL or volume loss on SPGR and rated the confidence in their evaluation.

RESULTS

Inter-rater reliability was superior in CASL (kappa = 0.7 in experienced readers) compared with SPGR (kappa = 0.17). CASL MR imaging had the highest sensitivity (85%) and accuracy (70%). Frontal lobe CASL findings increased sensitivity to 88% and accuracy to 79%. Fifty-seven percent of false-positive readings with CASL were in controls with cognitive decline or instability within 5 years. Three of the 4 readers revealed a statistically significant relationship between confidence and correct classification when using CASL.

CONCLUSIONS

Readers were able to separate individuals with mild AD from those with normal cognition with high sensitivity by using CASL but not volumetric MR imaging. This initial experience suggests that CASL MR imaging may be a useful technique for detecting AD.