Baseline diabetic status and admission blood glucose were poor prognostic factors in the EPITHET trial

BACKGROUND

Previous data have suggested that diabetes and hyperglycemia predict poor outcome following stroke. We studied the prognostic impact of diabetes and admission blood glucose in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET).

METHODS

EPITHET was a prospective randomized placebo-controlled trial of intravenous tissue plasminogen activator (tPA) in the 3- to 6-hour time window. A preexisting diagnosis of diabetes was noted and baseline serum glucose was measured.

RESULTS

Intravenous tPA attenuated infarct growth in non-diabetics, but not in diabetics (p = 0.029). In the tPA treatment group, admission blood glucose was higher among patients with poor functional outcome (p = 0.002).

CONCLUSIONS

Diabetes and hyperglycemia attenuate the effects of tPA on infarct evolution. Future thrombolytic trials should consider randomizing patients by subgroups based on diabetic status and serum glucose levels.

Penumbral mismatch is underestimated using standard volumetric methods and this is exacerbated with time

BACKGROUND AND AIMS

The mismatch between perfusion weighted images (PWI) and diffusion weighted images (DWI) using MR is increasingly being applied in patient selection for therapeutic trials. Two approaches to the calculation of the mismatch volume exist--the commonly used volumetric and the more precise co-registration method, the latter of which considers lesion topography. That there are differences in the mismatch volume analysed by each method and that these are time dependent was hypothesised.

METHODS

Patients within 48 h of ischaemic stroke onset had baseline MR PWI/DWI mismatch and T2 outcome volumes at 3 months. Volumetric mismatch volume was defined as PWI minus DWI lesion. Co-registration mismatch volume was defined as the PWI defect lesion not overlapped by the co-registered DWI lesion.

RESULTS

72 patients of median age 74.0 years were studied. Median baseline MR was at 5.9 h (IQR 3.0, 20.4 h) after stroke onset. Consistent underestimation of the mismatch volume occurred using the volumetric method (volumetric median 9.3 ml, IQR 0, 63 ml; co-registration median 20.1 ml, IQR 3.2, 69.8 ml; p<0.0001). This difference increased with time from stroke onset (p = 0.006).

CONCLUSIONS

Volumetric analysis consistently underestimates the PWI/DWI mismatch volume compared with the more precise co-registration method. This effect increases with time.

Imaging the penumbra - strategies to detect tissue at risk after ischemic stroke

The aim of thrombolytic therapy after acute ischemic stroke is salvage of the ischemic penumbra. Several imaging techniques have been used to identify the penumbra in patients who may benefit from reperfusion beyond the currently narrow 3-hour time-window for thrombolysis. We discuss the advantages and disadvantages of positron emission tomography (PET), single photon emission computed tomography (SPECT), MRI and CT scans. We comment on concepts of clinical-imaging mismatch models and we explore the implications for clinical trials.

Unhealthy behaviours for self-management of HIV-related peripheral neuropathy

The prevalence of peripheral neuropathy is frequent in HIV disease and is often associated with antiretroviral therapy. Unhealthy behaviours, particularly substance-use behaviours, are utilized by many HIV-positive individuals to manage neuropathic symptoms. As part of a larger study on self-care for symptoms in HIV disease, this study analyzed the prevalence and characteristics of unhealthy behaviours to self-manage peripheral neuropathy in HIV disease. Sociodemographic and disease-related correlates and unhealthy behaviours were examined in a convenience sample of 1,217 respondents who were recruited from data collection sites in several US cities, Puerto Rico, Colombia, and Taiwan. Results of the study indicated that respondents with peripheral neuropathy (n=450) identified a variety of unhealthy self-care behaviours including injection drug use, oral drug use, smoking cigarettes and alcohol ingestion. Specific unhealthy behaviours that participants reported to alleviate peripheral neuropathy included use of marijuana (n=67), smoking cigarettes (n=139), drinking alcohol (n=81) and street drugs (n=30). A subset of those individuals (n=160), who identified high levels of neuropathy (greater than five on a scale of 1-10), indicated significantly higher use of amphetamines and injection drug use in addition to alcohol use and cigarette smoking. For participants from Norway, substance use (using alcohol: 56%) was one of the most frequent self-management strategies. Implications for clinical practice include assessment and education of persons with HIV for self-care management of the complex symptom of peripheral neuropathy.

Symptom management and self-care for peripheral neuropathy in HIV/AIDS

Peripheral neuropathy is the most common neurological complication in HIV and is often associated with antiretroviral therapy. As part of a larger study on self-care for symptoms in HIV disease, this study analyzed the prevalence and characteristics of peripheral neuropathy in HIV disease, sociodemographic and disease-related correlates and self-care strategies. A convenience sample of 1,217 respondents was recruited from data collection sites in several US cities, Puerto Rico, Colombia and Taiwan. Results of the study indicated that respondents with peripheral neuropathy (n=450) identified 20 self-care behaviors including complementary therapies, use of medications, exercise and rest and/or elevation of extremities. Ratings of frequency and effectiveness were also included. An activities checklist summarized into five categories of self-care behaviors including activities/thoughts, exercise, medications, complementary therapies and substance was used to determine self-care behaviors. Taking a hot bath was the most frequent strategy used by those with peripheral neuropathy (n=292) and received the highest overall rating of effectiveness of any self-management strategies included in this study at 8.1 (scale 1-10). Other self-care strategies to manage this symptom included: staying off the feet (n=258), rubbing the feet with cream (n=177), elevating the feet (n=236), walking (n=262), prescribed anti-epileptic agent (n=80), prescribed analgesics (n=84), over-the-counter medications (n=123), vitamin B (n=122), calcium supplements (n=72), magnesium (n=48), massage (n=156), acupuncture (n=43), reflexology (n=23) and meditation (n=80). Several behaviors that are often deemed unhealthy were included among the strategies reported to alleviate peripheral neuropathy including use of marijuana (n=67), cigarette smoking (n=139), drinking alcohol (n=81) and street drugs (n=30).

Hematoma growth is a determinant of mortality and poor outcome after intracerebral hemorrhage

BACKGROUND

Although volume of intracerebral hemorrhage (ICH) is a predictor of mortality, it is unknown whether subsequent hematoma growth further increases the risk of death or poor functional outcome.

METHODS

To determine if hematoma growth independently predicts poor outcome, the authors performed an individual meta-analysis of patients with spontaneous ICH who had CT within 3 hours of onset and 24-hour follow-up. Placebo patients were pooled from three trials investigating dosing, safety, and efficacy of rFVIIa (n = 115), and 103 patients from the Cincinnati study (total 218). Other baseline factors included age, gender, blood glucose, blood pressure, Glasgow Coma Score (GCS), intraventricular hemorrhage (IVH), and location.

RESULTS

Overall, 72.9% of patients exhibited some degree of hematoma growth. Percentage hematoma growth (hazard ratio [HR] 1.05 per 10% increase [95% CI: 1.03, 1.08; p < 0.0001]), initial ICH volume (HR 1.01 per mL [95% CI: 1.00, 1.02; p = 0.003]), GCS (HR 0.88 [95% CI: 0.81, 0.96; p = 0.003]), and IVH (HR 2.23 [95% CI: 1.25, 3.98; p = 0.007]) were all associated with increased mortality. Percentage growth (cumulative OR 0.84 [95% CI: 0.75, 0.92; p < 0.0001]), initial ICH volume (cumulative OR 0.94 [95% CI: 0.91, 0.97; p < 0.0001]), GCS (cumulative OR 1.46 [95% CI: 1.21, 1.82; p < 0.0001]), and age (cumulative OR 0.95 [95% CI: 0.92, 0.98; p = 0.0009]) predicted outcome modified Rankin Scale. Gender, location, blood glucose, and blood pressure did not predict outcomes.

CONCLUSIONS

Hematoma growth is an independent determinant of both mortality and functional outcome after intracerebral hemorrhage. Attenuation of growth is an important therapeutic strategy.

Elevated hematocrit is associated with reduced reperfusion and tissue survival in acute stroke

BACKGROUND

Elevated hematocrit (Hct) contributes to blood viscosity and has an adverse effect in acute stroke. The authors investigated the influence of Hct on tissue fate using serial MRI in acute stroke patients.

METHODS

The effects of Hct on reperfusion, penumbral salvage, and infarct expansion in 64 patients presenting within 24 hours of stroke onset were measured. MRI was performed at baseline (< 24 hours), days 3 to 5, and 90 days from stroke onset.

RESULTS

Median Hct was 42% with a bimodal distribution. There was a strong inverse relationship between Hct and reperfusion (Spearman rho = -0.74, p < 0.0001). The odds of major reperfusion (> 50% resolution of the baseline perfusion-weighted imaging deficit) were significantly lower with increasing Hct (odds ratio [OR] = 0.53; 95% CI = 0.97 to 1.00), independent of age, perfusion, and diffusion lesion volumes and recombinant tissue plasminogen activator (rtPA) administration. There was a trend toward reduced penumbral salvage at days 3 to 5 with increasing Hct (p = 0.06, 95% CI = -4.76 to 0.14). An increasing Hct was a significant predictor of infarct growth (OR = 1.26, 95% CI = 1.00 to 1.59), independent of baseline perfusion and diffusion volumes and glucose. The effect of Hct on reperfusion and infarct expansion was similar irrespective of rtPA administration (p = 0.31) and independent of smoking status.

CONCLUSIONS

Higher hematocrit (Hct) values have a significant independent association with reduced reperfusion and greater infarct size after ischemic stroke. An elevated Hct may also be a potential physiologic determinant of reduced penumbral salvage.

Medical management of haemorrhagic stroke

Intracerebral haemorrhage (ICH) is much less common than ischaemic stroke (15% versus 85% in most Western studies), but is associated with a significantly worse prognosis. ICH is much more common in Asian populations, probably reflecting higher rates of small vessel disease, hypertension and genetic factors. Overall, ICH mortality rates approach 50% and there has been little effective treatment to date, except for the overall benefit from stroke unit care. Surgery for supratentorial ICH was not shown to be beneficial in a large recent trial of over 1000 patients, although controversies remain. For example, it still has an important role in selected patients with cerebellar ICH. Medical therapies to reduce brain edema and intracranial pressure, including glycerol and mannitol, are not of proven value. It is accepted that corticosteroids should not be used in ICH and may worsen outcomes. The management of acute hypertension is controversial and guidelines are based on little direct evidence.

Results of a Multicentre, Randomised Controlled Trial of Intra-Arterial Urokinase in the Treatment of Acute Posterior Circulation Ischaemic Stroke

BACKGROUND

Patients with ischaemic stroke due to occlusion of the basilar or vertebral arteries may develop a rapid deterioration in neurological status leading to coma and often to death. While intra-arterial thrombolysis may be used in this context, no randomised controlled data exist to support its safety or efficacy.

METHODS

Randomised controlled trial of intra-arterial urokinase within 24 h of symptom onset in patients with stroke and angiographic evidence of posterior circulation vascular occlusion.

RESULTS

Sixteen patients were randomised, and there was some imbalance between groups, with more severe strokes occurring in the treatment arm. A good outcome was observed in 4 of 8 patients who received intra-arterial urokinase compared with 1 of 8 patients in the control group.

CONCLUSIONS

These results support the need for a large-scale study to establish the efficacy of intra-arterial thrombolysis for acute basilar artery occlusion.

Cooling for Acute Ischemic Brain Damage (COOL AID): a feasibility trial of endovascular cooling

OBJECTIVE

To report results of a randomized pilot clinical feasibility trial of endovascular cooling in patients with ischemic stroke.

METHODS

Forty patients with ischemic stroke presenting within 12 hours of symptom onset were enrolled in the study. An endovascular cooling device was inserted into the inferior vena cava of those randomized to hypothermia. A core body temperature of 33 degrees C was targeted for 24 hours. All patients underwent clinical assessment and MRI initially, at days 3 to 5 and days 30 to 37.

RESULTS

Eighteen patients were randomized to hypothermia and 22 to receive standard medical management. Thirteen patients reached target temperature in a mean of 77 +/- 44 minutes. Most tolerated hypothermia well. Clinical outcomes were similar in both groups. Mean diffusion-weighted imaging (DWI) lesion growth in the hypothermia group (n = 12) was 90.0 +/- 83.5% compared with 108.4 +/- 142.4% in the control group (n = 11) (NS). Mean DWI lesion growth in patients who cooled well (n = 8) was 72.9 +/- 95.2% (NS).

CONCLUSIONS

Induced moderate hypothermia is feasible using an endovascular cooling device in most patients with acute ischemic stroke. Further studies are needed to determine if hypothermia improves outcome.

Magnetic resonance imaging criteria for thrombolysis in acute cerebral infarct

BACKGROUND AND PURPOSE

Magnetic resonance imaging (MRI) selection of stroke patients eligible for thrombolytic therapy is an emerging application. Although the efficacy of therapy within 3 hours after onset of symptoms with intravenous (IV) tissue plasminogen activator (tPA) has been proven for patients selected with computed tomography (CT), no randomized, double-blinded MRI trial has been published yet.

SUMMARY OF REVIEW

MRI screening of acute stroke patients before thrombolytic therapy is performed in some cerebrovascular centers. In contrast to the CT trials, MRI pilot studies demonstrate benefit of therapy up to 6 hours after onset of symptoms. This article reviews the literature that has lead to current controlled MRI-based thrombolysis trials. We examined the MRI criteria applied in 5 stroke centers. Along with the personal views of clinicians at these centers, the survey reveals a variety of clinical and MRI technical aspects that must be further investigated: the therapeutic consequence of microbleeds, the use of magnetic resonance angiography, dynamic time windows, and others.

CONCLUSION

MRI is an established application in acute evaluation of stroke patients and may suit as a brain clock, replacing the currently used epidemiological time clock when deciding whether to initiate thrombolytic therapy. MRI criteria for thrombolytic therapy are applied in some cerebrovascular centers, but the results of ongoing clinical trials must be awaited before it is possible to reach consensus.

Is Doppler ultrasound sufficient as the sole investigation before carotid endarterectomy?

BACKGROUND AND AIMS

Doppler ultrasound (DU) of the extracranial carotid arteries has been advocated as the sole imaging modality in carotid endarterectomy (CE) candidates. However this approach fails to identify patients with potentially significant intracranial disease, at high risk of stroke and death. Therefore, many stroke clinicians recommend angiography after screening DU. We aimed to identify the proportion of cases referred for CE in whom the identification of intracranial disease could have altered management.

METHODS

Two neuroradiologists, blinded to the clinical history, reviewed the films of 111 CE candidates, predominantly of Caucasian background, who had undergone carotid angiography after screening DU. Intracranial stenoses >50% luminal diameter, incidental aneurysms and non-atherosclerotic lesions were documented. Demographic and epidemiological data were collected.

RESULTS

Of the 111 patients, 87 had >50% extracranial stenoses although two thirds were asymptomatic. Intracranial stenotic lesions were recorded in 29% of patients. Over half of these were tandem lesions, distal to an extracranial stenosis. Aneurysms were found in 4.5% of patients.

CONCLUSIONS

DU alone would have failed to detect significant intracranial disease in nearly a third of cases. These patients are at high risk of stroke. The identification of this group allows more aggressive stroke prevention therapy.

Self-care management for neuropathy in HIV disease

Peripheral neuropathy is the most common neurological complication in HIV and is often associated with antiretroviral therapy. As part of a larger study on self-care for symptoms in HIV disease, this study analyzed the prevalence and characteristics of peripheral neuropathy in HIV disease, the self-care strategies, and sources of information for self-care utilized by the sample. A convenience sample of 422 respondents was recruited from an Internet web-based site developed by the University of California, San Francisco International HIV/AIDS Research Network and from five geographic data collection sites (Boston, New York City, San Francisco and Paterson in the USA, and Oslo, Norway). Results of the study indicated that respondents with peripheral neuropathy identified 77 self-care behaviours including complementary therapies, use of medications, exercise and rest and/or elevation of extremities. Sources of information included health care providers, informal networks and media sources.

Baseline blood pressure but not early computed tomography changes predicts major hemorrhage after streptokinase in acute ischemic stroke

BACKGROUND AND PURPOSE

Intracerebral hemorrhage is the most serious complication of thrombolytic therapy for stroke. We explored factors associated with this complication in the Australian Streptokinase Trial.

METHODS

The initial CT scans (< or =4 hours after stroke) of 270 patients were reviewed retrospectively by an expert panel for early signs of ischemia and classified into the following 3 categories: no signs or < or =1/3 or >1/3 of the vascular territory. Hemorrhage on late CT scans was categorized as major or minor on the basis of location and mass effect. Stepwise, backward elimination, multivariate logistic regression analysis was used to identify risk factors for each hemorrhage category.

RESULTS

Major hemorrhage occurred in 21% of streptokinase (SK) and 4% of placebo patients. Predictors of major hemorrhage were SK treatment (odds ratio [OR], 6.40; 95% CI, 2.50 to 16.36) and elevated systolic blood pressure before therapy (OR, 1.03; 95% CI, 1.01 to 1.05). Baseline systolic blood pressure >165 mm Hg in SK-treated patients resulted in a >25% risk of major secondary hemorrhage. Early ischemic CT changes, either < or =1/3 or >1/3, were not associated with major hemorrhage (OR, 1.58; 95% CI, 0.65 to 3.83; and OR, 1.11; 95% CI, 0.45 to 2.76, respectively). Minor hemorrhage occurred in 30% of the SK and 26% of the placebo group. Predictors of minor hemorrhage were male sex, severe stroke, early CT changes, and SK treatment. Ninety-one percent of patients with major hemorrhage deteriorated clinically compared with 23% with minor hemorrhage.

CONCLUSIONS

SK increased the risk of both minor and major hemorrhage. Major hemorrhage was also more likely in patients with elevated baseline systolic blood pressure. However, early CT changes did not predict major hemorrhage. Results from this study highlight the importance of baseline systolic blood pressure as a potential cause of hemorrhage in patients undergoing thrombolysis.

Patterns of physical activity among American Indian children: an assessment of barriers and support

Estimates indicate that 10% to 50% of American Indian and non-Indian children in the U.S. are obese, defined as a body mass index > or = 95th percentile of the NHANES II reference data. Pathways is a two-phase, multi-site study to develop and test a school-based obesity prevention program in American Indian schoolchildren in grades three through five. During Phase I feasibility prior to initiation of the Pathways trial, data were collected related to physical activity patterns, and the supports of, and barriers to, physical activity. Nine schools from communities representing six different tribal groups participated in this study. Multiple measures were used for data collection including direct observation, paired child interviews, and in-depth interviews and focus groups with adults. Students completed the self-administered Knowledge, Attitudes, and Behaviors (KAB) survey, and a Physical Activity Questionnaire (PAQ). Barriers to physical activity at schools included a lack of facilities, equipment, and trained staff persons for PE. Adults were not consistently active with their children, but they were highly supportive of their children's activity level. Children reported a strong enjoyment of physical activity and strong peer support to be physically active. Weather conditions, safety concerns, and homework/chores were common barriers to physical activity reported by children and adult caregivers. The information was used to design culturally and age-appropriate, practical interventions including the five physical activity programs for schoolchildren in the Pathways study.

The value of apparent diffusion coefficient maps in early cerebral ischemia

BACKGROUND AND PURPOSE

Prediction of the regions of the ischemic penumbra that are likely to progress to infarction is of great clinical interest. Whether lowered apparent diffusion coefficient (ADC) values were present in the ischemic penumbra of patients presenting with acute ischemic stroke and were specific to regions of the penumbra that proceeded to infarction was investigated.

METHODS

Nineteen patients with hemispheric stroke of less than 6 hours' onset and with acute scans showing a perfusion lesion greater than a diffusion lesion (ischemic penumbra) were studied. Scans also were performed subacutely (days 3 to 5) and at outcome (day 90). The outcome scan was used to identify regions of the penumbra that proceeded to infarction.

RESULTS

The ADC ratios were significantly reduced (P <.00001) in regions of the penumbra that progressed to infarction on the outcome scan compared with those that remained normal. In regions that showed transition to infarction, the mean ADC ratios were typically 0.75 to 0.90.

CONCLUSION

Intermediate ADC values are present in the ischemic penumbra and are indicative of tissue at risk of infarction.

Perfusion magnetic resonance imaging maps in hyperacute stroke: relative cerebral blood flow most accurately identifies tissue destined to infarct

BACKGROUND AND PURPOSE

In ischemic stroke, perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) provide important pathophysiological information. A PWI>DWI mismatch pattern suggests the presence of salvageable tissue. However, improved methods for distinguishing PWI>DWI mismatch tissue that is critically hypoperfused from benign oligemia are required.

METHODS

We investigated the usefulness of maps of relative cerebral blood flow (rCBF), volume (rCBV), and mean transit time (rMTT) to predict transition to infarction in hyperacute (<6 hours) stroke patients with PWI>DWI mismatch patterns. Semiquantitative color-thresholded analysis was used to measure hypoperfusion volumes, including increasing color signal intensity thresholds of rMTT delay, which were compared with infarct expansion, outcome infarct size, and clinical status.

RESULTS

Acute rCBF lesion volume had the strongest correlation with final infarct size (r=0.91, P<0.001) and clinical outcome (r=0.67, P<0.01). There was a trend for acute rCBF>DWI mismatch volume to overestimate infarct expansion between the acute and outcome study (P=0.06). Infarct expansion was underestimated by acute rCBV>DWI mismatch (P<0.001). When rMTT lesions included tissue with moderately prolonged transit times (mean delay 4.3 seconds, signal intensity values 50% to 70%), infarct expansion was overestimated. In contrast, when rMTT lesions were restricted to more severely prolonged transit times (mean delay 6.1 seconds, signal intensity >70%), these regions progressed to infarction in all except 1 patient, but infarct expansion was underestimated (P<0.001).

CONCLUSIONS

The acute rCBF lesion most accurately identified tissue in the PWI>DWI mismatch region at risk of infarction. Color-thresholded PWI maps show potential for use in an acute clinical setting to prospectively predict tissue outcome.

Q methodology: a new way of assessing employee satisfaction

As yet another nursing shortage faces the country, the issue of the satisfaction of nurses again becomes of critical concern to nursing managers in the interest of staff retention. The authors describe the use of the statistical technique Q methodology to assess the needs of nurses and other medical staff at a level one, tertiary care emergency department in the United States. Using the Q method, the authors were able to identify different, unique viewpoints concerning employee needs among the study population, as well as commonly shared views. This level of detail, not obtainable using more traditional statistical techniques, can aid in the design of more effective strategies aimed at fulfilling the needs of an organization's staff to increase their satisfaction.

Prediction of the final infarct volume within 6 h of stroke using single photon emission computed tomography with technetium-99m hexamethylpropylene amine oxime

BACKGROUND

A simple method to predict the final infarct volume within 6 h of onset of hemispheric ischemic stroke based on the measurement of cerebral blood flow (CBF) using single photon emission computed tomography (SPECT) with techneticum-99m hexamethylpropylene amine oxime ((99m)Tc-HMPAO) was investigated in a clinical model involving patients without definite early reperfusion or clinical recovery.

METHODS

A group of 16 patients (group 1) was used to establish the methodology, which was then validated in a second group of 14 patients (group 2). The final infarct volume was defined using computed tomography (CT) performed at least 7 days after stroke. The relative CBF threshold value, expressed as a percentage of the mean contralateral hemispheric value, which most closely estimated the final infarct size on coregistered CT was established for each patient.

RESULTS

The mean threshold CBF value for group 1 was 63.7%. When this value was used to predict infarct size in group 2, a close correlation was observed between the actual and the estimated sizes (r = 0.973, p < 0.0001). This value was not time dependent.

CONCLUSIONS

If no significant early reperfusion or clinical recovery occurs, a CBF threshold value of 63.7% on (99m)Tc-HMPAO SPECT performed within 6 h of stroke onset will reliably predict the final infarct size.

Comparison of MRI perfusion imaging and single photon emission computed tomography in chronic stroke

There have been few direct comparisons between MR perfusion-weighted imaging (PWI) and established perfusion imaging techniques, and none in chronic stroke. We therefore studied 17 chronic hemispheric infarction patients (mean, 90 days) and compared hypoperfusion volumes determined from PWI maps of relative cerebral blood flow (rCBF) and volume (rCBV), and mean transit time (rMTT) with those measured with (99)Tc-HMPAO single photon emission computed tomography (SPECT). Comparisons were also made between infarct size (T(2)-WI) and clinical scales. Correlations were found between lesion location and volume in all three PWI hemodynamic parameter maps with clinical state and lesions on SPECT and T(2)-WI. In 3 patients, rCBF and rCBV lesions extended well beyond the borders of moderate-sized infarctions. We conclude that in chronic stroke, PWI can delineate regions of abnormal perfusion that reflect the degree of functional impairment and structural damage. The finding of peri-infarct hypoperfusion suggests that PWI may have the potential to provide a rapid and non-invasive template against which interventional strategies aimed at promoting functional recovery may be investigated.