Regional very low cerebral blood volume predicts hemorrhagic transformation better than diffusion-weighted imaging volume and thresholded apparent diffusion coefficient in acute ischemic stroke

Blood-brain barrier disruption and hemorrhagic transformation in acute stroke before endovascular reperfusion therapy

Background and purpose

Early blood-brain barrier (BBB) disruption in patients with acute ischemic stroke (AIS) can be detected on perfusion computed tomography (PCT) images before undergoing reperfusion therapy. In this study, we aimed to determine whether early disruption of the BBB predicts intracranial hemorrhage transformation (HT) in patients with AIS undergoing endovascular therapy and further identify factors influencing BBB disruption.

Methods

We retrospectively analyzed general clinical and imaging data derived from 159 consecutive patients with acute anterior circulation stroke who were admitted to the Department of Neurology of the First Hospital of Jilin University, and who underwent endovascular treatment between January 1, 2021, and March 31, 2023. We evaluated the relationship between BBB destruction and intracranial HT before endovascular reperfusion therapy and examined the risk factors for early BBB destruction.

Results

A total of 159 patients with assessable BBB leakage were included. The median (interquartile range, IQR) age was 63 (54-70) years, 108 (67.9%) patients were male, and the median baseline National Institutes of Health Stroke Scale (NHISS) score was 12 (10-15). Follow-up non-contrast computed tomography (NCCT) detected HT in 63 patients. After logistic regression modeling adjustment, we found that BBB leakage in the true leakage area was slightly more than 2-fold risk of HT (odds ratio [OR], 2.01; 95% confidence interval [CI] 1.02-3.92). Heart rate was also associated with HT (OR, 1.03, 95% CI, 1.00-1.05). High Blood-brain barrier permeability (BBBP) in the true leakage area was positively correlated with infarct core volume (OR, 1.03; 95% CI, 1.01-1.05).

Conclusion

Early BBB destruction before endovascular reperfusion therapy was associated with HT, whereas high BBBP correlated positively with infarct core volume.

Magnetic Resonance Perfusion-Weighted Imaging in Predicting Hemorrhagic Transformation of Acute Ischemic Stroke: A Retrospective Study

Hemorrhagic transformation (HT) is one of the common complications in patients with acute ischemic stroke (AIS). This study aims to investigate the value of different thresholds of Tmax generated from perfusion-weighted MR imaging (PWI) and the apparent diffusion coefficient (ADC) value in the prediction of HT in AIS. A total of 156 AIS patients were enrolled in this study, with 55 patients in the HT group and 101 patients in non-HT group. The clinical baseline data and multi-parametric MRI findings were compared between HT and non-HT groups to identify indicators related to HT. The optimal parameters for predicting HT and the corresponding cutoff values were obtained using the receiver operating characteristic curve analysis of the volumes of ADC < 620 × 10-6 mm2/s and Tmax > 6 s, 8 s, and 10 s. The results showed that the volumes of ADC < 620 × 10-6 mm2/s and Tmax > 6 s, 8 s, and 10 s in the HT group were all significantly larger than that in the non-HT group and were all independent risk factors for HT. Early measurement of the volume of Tmax > 10 s had the highest value, with a cutoff lesion volume of 10.5 mL.

A clinical-radiomics model based on noncontrast computed tomography to predict hemorrhagic transformation after stroke by machine learning: a multicenter study

OBJECTIVE

To build a clinical-radiomics model based on noncontrast computed tomography images to identify the risk of hemorrhagic transformation (HT) in patients with acute ischemic stroke (AIS) following intravenous thrombolysis (IVT).

MATERIALS AND METHODS

A total of 517 consecutive patients with AIS were screened for inclusion. Datasets from six hospitals were randomly divided into a training cohort and an internal cohort with an 8:2 ratio. The dataset of the seventh hospital was used for an independent external verification. The best dimensionality reduction method to choose features and the best machine learning (ML) algorithm to develop a model were selected. Then, the clinical, radiomics and clinical-radiomics models were developed. Finally, the performance of the models was measured using the area under the receiver operating characteristic curve (AUC).

RESULTS

Of 517 from seven hospitals, 249 (48%) had HT. The best method for choosing features was recursive feature elimination, and the best ML algorithm to build models was extreme gradient boosting. In distinguishing patients with HT, the AUC of the clinical model was 0.898 (95% CI 0.873-0.921) in the internal validation cohort, and 0.911 (95% CI 0.891-0.928) in the external validation cohort; the AUC of radiomics model was 0.922 (95% CI 0.896-0.941) and 0.883 (95% CI 0.851-0.902), while the AUC of clinical-radiomics model was 0.950 (95% CI 0.925-0.967) and 0.942 (95% CI 0.927-0.958) respectively.

CONCLUSION

The proposed clinical-radiomics model is a dependable approach that could provide risk assessment of HT for patients who receive IVT after stroke.

Value of sildenafil treatment for the prevention of vasospasm‑related delayed ischemic neurological deficits and delayed brain infarction following aneurysmal subarachnoid hemorrhage

Cerebral vasospasm (CV) or delayed cerebral ischemia (DCI) constitutes the main reason for the unfavorable outcomes of patients with aneurysmal subarachnoid hemorrhage (aSAH). The present retrospective cohort study, through an evaluation with computed tomography (CT) perfusion (CTP), aimed to examine the utility of an intravenous or oral administration of sildenafil in preventing DCI that develops due to vasospasm in these patients. A retrospective cohort study was conducted, which included 34 patients in a tertiary care hospital. Of these patients, 18 were males (52.9%), and the median age was 54.4 years. Of these patients, 18 (52.9%) had undergone surgery, and 16 (47.1%) had an endovascular procedure. CTP was performed on the 3rd to the 6th day. The clinical outcome was documented at 30 days using a CT scan and a complete neurological evaluation, including the Glasgow Coma Scale assessment. There was a statistically significant difference in the number of patients who developed an ischemic event at 1 month between those who did not receive sildenafil compared to those who received sildenafil (P<0.05). In addition, the multivariate analysis revealed that cerebral blood flow was an independent factor for detecting an ischemic event in 1 month (P=0.001). On the whole, the findings of the present study indicate that the intravenous or oral administration of sildenafil may be beneficial for the prevention of DCI.

Early diagnosis of cerebral vasospasm associated with cerebral ischemia following subarachnoid hemorrhage: Evaluation of computed tomography perfusion and transcranial doppler as accurate methods

Cerebral vasospasm (CV) constitutes a major post-operative complication and source of morbidity in cases of subarachnoid hemorrhage (SAH). The early detection of CV in SAH may be difficult both clinically and radiographically. The present pilot study thus aimed to evaluate the practicability of the technique in a tertiary healthcare setting and to assess the diagnostic effectiveness of various diagnostic computed tomography (CT) perfusion (CTP) aspects in predicting the clinical outcome of patients with SAH (traumatic and aneurysmal). A retrospective study including 34 patients in a tertiary care hospital was thus conducted. The results revealed that of the 34 patients, 18 (52.9%) were males, and the mean age was 54.4±18.5 years (16-85 years old; range, 69 years). In total, 15 (44.1%) patients had traumatic SAH following traumatic brain injury (TBI), 11 (33.3%) had aneurysmal SAH, and 8 patients (23.6%) presented with TBI without SAH as controls. CTP was performed on the third to the sixth day, and 15-20 min prior to CPT, a transcranial Doppler ultrasound was performed. Clinical outcomes were documented at 30 days using a CT scan and a complete neurological evaluation, including Glasgow Coma Scale assessment. The results of a multivariate analysis revealed that cerebral blood flow (CBF) was an independent factor for detecting an ischemic event in 1 month (P=0.003). On the whole, the present study demonstrates that CTP, and consequently CBF, is a considerable index that may identify the onset of cerebral ischemia in patients with SAH.

Analysis of Factors Associated with Hemorrhagic Transformation in Acute Cerebellar Infarction

OBJECTIVES

Hemorrhagic transformation (HT) is a frequent and severe complication of ischemic stroke. This study aimed to evaluate the factors associated with the occurrence of HT in patients with acute cerebellar infarction.

MATERIALS AND METHODS

A total of 190 patients, 141 male (74.2%) and 49 female (25.8%) with mean age 61.84 ± 12.16 years, who were admitted within 72 h of acute cerebellar infarction onset from January 2017 to March 2021 were retrospectively recruited. The multivariate logistic regression analysis was used to evaluate the independent influent factors for HT and receiver-operating characteristic (ROC) curve was applied to calculate the predictive value of those factors for HT in patients with acute cerebellar infarction.

RESULTS

37 out of 190 recruited patients (19.47%) had HT within 14 days after acute cerebellar infarction onset. The incidence rates of HT occurring within 3 days, 3-7 days and 7-14 days were 13.5%, 40.5% and 45.9%, respectively. Results of the multivariable logistic regression analysis indicated that atrial fibrillation (AF) (OR 6.196, 95% CI 1.357-28.302, P = 0.019), infarct diameter (OR 5.813, 95% CI 2.932-11.526, P < 0.001), white matter hyperintensity (WMH) (OR 2.44, 95% CI 1.134-5.252, P = 0.023) were independent risk factors for HT in acute cerebellar infarction, while lymphocyte count (OR 0.319, 95% CI 0.142-0.716, P = 0.006) showed an independently protective effect.

CONCLUSIONS

Infarct diameter, AF and WMH are independent risk factors for HT in patients with acute cerebellar infarction, while the lymphocyte count is a protective factor.

Hemorrhagic Transformation in Acute Ischemic Stroke: A Quantitative Systematic Review

The prevalence and risk factors of hemorrhagic transformation (HT) after acute ischemic stroke HT have not been adequately delineated. We performed a systematic review and meta-analysis to identify English-language prospective observational MEDLINE and EMBASE-listed reports of acute ischemic stroke with HT published from 1985–2017. Studies that used the ECASS-2 definitions of hemorrhagic transformation subtypes, hemorrhagic infarction (HI), and parenchymal hematoma (PH) were included. Patients treated with intravenous thrombolysis with tissue plasminogen activator (IV-tPA) were compared with those who did not receive thrombolysis. A total of 65 studies with 17,259 patients met inclusion criteria. Overall, HT prevalence was 27%; 32% in patients receiving IV-tPA vs. 20% in those without. Overall PH prevalence was 9%; 12% in IV-tPA treated patients vs. 5% in those without. HT was associated with a history of atrial fibrillation (OR 2.94) and use of anticoagulants (OR 2.47). HT patients had higher NIHSS (Hedge’s-G 0.96) and larger infarct volume (diffusion-weighted MRI, Hedge’s-G 0.8). In IV-tPA treated patients, PH correlated with antiplatelet (OR 3) and statin treatment (OR 4). HT (OR 3) and PH (OR 8) were associated with a poor outcome at 90-day (mRS 5–6). Hemorrhagic transformation is a frequent complication of acute ischemic stroke and is associated with poor outcome. Recognition of risk factors for HT and PH may reduce their incidence and severity.

Sub-lethal effects of soil multiple contamination on the avoidance behaviour of Eisenia fetida

Natural ecosystems are frequently exposed to complex mixtures of different chemicals. However, the environmental risk assessment is mainly based on data from individual substances. In this study, the individual and combined effects on the terrestrial earthworm E. fetida exposed to the anionic surfactant sodium lauryl ether sulphate (SLES) and the pesticides chlorpyrifos (CPF) and imidacloprid (IMI) were investigated, by using the avoidance behaviour as endpoint. Earthworms were exposed to a soil artificially contaminated with five sub-lethal concentrations of each contaminant, both as single substances and in combination of binary and ternary mixtures. Overall results showed that IMI provoked the highest avoidance effect on earthworms, with a concentration value that induced an avoidance rate of 50% of treated organisms (AC50) of 1.30 mg/kg, followed by CPF (AC50 75.26 mg/kg) and SLES (AC50 139.67 mg/kg). The application of the Combination Index (CI) method, indicated that a deviation from the additive response occurred for most of the tested chemical mixtures, leading to synergistic or antagonistic avoidance responses. Synergistic effects were produced by the exposure to the two lowest concentrations of the CPF+IMI mixture, and by the highest concentrations of SLES+CPF and SLES+CPF+IMI mixtures. On the contrary, antagonistic effects were observed at the lowest concentrations of the binary mixtures containing the SLES and at almost all the tested concentrations of the SLES+CPF+IMI mixture (with the exception of the highest tested concentration). These results show that the avoidance test is suitable to assess the detrimental effects exerted on earthworms by chemical mixtures in soil ecosystems and the use of behavioural endpoints can increase the ecological significance of environmental risk assessment procedures.

Nomogram to predict haemorrhagic transformation after stroke thrombolysis: a combined brain imaging and clinical study

AIM

To construct a novel nomogram by integrating computed tomography perfusion (CTP) and clinical parameters for individualised prediction of haemorrhagic transformation (HT) in intravenous thrombolysis (IVT)-treated acute ischaemic stroke (AIS) patients.

METHODS

Anterior circulation AIS patients who underwent IVT at a single centre from January 2018 to June 2020 were reviewed retrospectively. The CTP parameters of two regions of interest (ROI), the entire perfusion lesion areas, and the infract core areas, were assessed. HT was documented by follow-up CT 24 ± 2 h after IVT. Multivariable logistic regression was conducted by including clinical variables and CTP parameters to identify the independent predictors of HT. A nomogram was developed based on the independent predictors. The discriminative value and calibration of the nomogram were tested by concordance indexes (C-indexes) and calibration plots. Internal validation was performed using fivefold cross-validation.

RESULTS

The nomogram was generated using the complete data from 341 patients. Seven variables were included in the final nomogram, including: the relative cerebral blood volume (rCBV), permeability surface (PS), and relative PS (rPS) in infract core areas, the relative time to maximum (rTmax) and rPS in entire perfusion lesion areas, the National Institutes of Health Stroke Scale (NIHSS), and atrial fibrillation (AF). The C-indexes were 0.815 and 0.817 for the nomogram and internal validation. The calibration plots showed excellent agreement.

CONCLUSION

This is the first study establishing a nomogram based on CTP and clinical parameters to predict HT after stroke thrombolysis.

Blood-brain barrier leakage and hemorrhagic transformation: The Reperfusion Injury in Ischemic StroKe (RISK) study

BACKGROUND AND PURPOSE

In patients with acute ischemic stroke treated with reperfusion therapy we aimed to evaluate whether pretreatment blood-brain barrier (BBB) leakage is associated with subsequent hemorrhagic transformation (HT).

METHODS

We prospectively screened patients with acute ischemic stroke treated with intravenous thrombolysis and/or endovascular treatment. Before treatment, each patient received computed tomography (CT), CT angiography, and CT perfusion. We assessed pretreatment BBB leakage within the ischemic area using the volume transfer constant (K^trans ) value. Our primary outcome was relevant HT, defined as hemorrhagic infarction type 2 or parenchymal hemorrhage type 1 or 2. We evaluated independent associations between BBB leakage and HT using logistic regression, adjusting for age, sex, baseline stroke severity, Alberta Stroke Program Early CT Score (ASPECTS) ≥ 6, treatment type, and onset-to-treatment time.

RESULTS

We enrolled 171 patients with available assessment of BBB leakage. The patients' mean (±SD) age was 75.5 (±11.8) years, 86 (50%) were men, and the median (interquartile range) National Institutes of Health Stroke Scale score was 18 (12-23). A total of 32 patients (18%) received intravenous thrombolysis, 102 (60%) underwent direct endovascular treatment, and 37 (22%) underwent both. Patients with relevant HT (N = 31;18%) had greater mean BBB leakage (K^trans 0.77 vs. 0.60; p = 0.027). After adjustment in the logistic regression model, we found that BBB leakage was associated both with a more than twofold risk of relevant HT (odds ratio [OR] 2.50; 95% confidence interval [CI] 1.03-6.03 per K^trans point increase; OR 2.34; 95% CI 1.06-5.17 for K^trans values > 0.63 [mean BBB leakage value]) and with symptomatic intracerebral hemorrhage (OR 4.30; 95% CI 1.13-13.77 per K^trans point increase).

CONCLUSION

Pretreatment BBB leakage before reperfusion therapy was associated with HT, and may help to identify patients at risk of HT.

Imaging for Predicting Hemorrhagic Transformation of Acute Ischemic Stroke-A Narrative Review

Hemorrhagic transformation is caused by extravasation of blood products from vessels after acute ischemic stroke. It is an undesirable and potentially devastating complication, which occurs in 10%-40% of clinical cases. Hemorrhagic transformation is classified into four subtypes based on European cooperative acute stroke study II. Predicting hemorrhagic complications at presentation can be useful life saving/altering decisions for the patient. Also, understanding the mechanisms of hemorrhagic transformation can lead to new treatments and intervention measures. We highlighted various imaging techniques that have been used to predict hemorrhagic transformation. Specifically, we looked at the usefulness of perfusion and permeability imaging for hemorrhagic transformation. Use of imaging to predict hemorrhagic transformation could change patient management that may lead to the prevention of hemorrhagic transformation before it occurs. We concluded that the current evidence is not strong enough to rely on these imaging parameters for predicting hemorrhagic transformation and more studies are required.

Neuroimaging in Acute Stroke

PURPOSE OF REVIEW

This article describes how imaging can be used by physicians in diagnosing, determining prognosis, and making appropriate treatment decisions in a timely manner in patients with acute stroke.

RECENT FINDINGS

Advances in acute stroke treatment, including the use of endovascular thrombectomy in patients with large vessel occlusion and, more recently, of IV thrombolysis in an extended time window, have resulted in a paradigm shift in how imaging is used in patients with acute stroke. This paradigm shift, combined with the understanding that "time is brain," means that imaging must be fast, reliable, and available around the clock for physicians to make appropriate clinical decisions. CT has therefore become the primary imaging modality of choice. Recognition of a large vessel occlusion using CT angiography has become essential in identifying patients for endovascular thrombectomy, and techniques such as imaging collaterals on CT angiography or measuring blood flow to predict tissue fate using CT perfusion have become useful tools in selecting patients for acute stroke therapy. Understanding the use of these imaging modalities and techniques in dealing with an emergency such as acute stroke has therefore become more important than ever for physicians treating patients with acute stroke.

SUMMARY

Imaging the brain and the blood vessels supplying it using modern tools and techniques is a key step in understanding the pathophysiology of acute stroke and making appropriate and timely clinical decisions.

Clinical Characteristics and Outcome of Patients With Hemorrhagic Transformation After Intravenous Thrombolysis in the WAKE-UP Trial

Background: Hemorrhagic transformation (HT) is an important complication of intravenous thrombolysis with alteplase. HT can show a wide range from petechiae to parenchymal hematoma with mass effect with varying clinical impact. We studied clinical and imaging characteristics of patients with HT and evaluated whether different types of HT are associated with functional outcome.

Methods: We performed a post-hoc analysis of WAKE-UP, a multicenter, randomized, placebo-controlled trial of MRI-guided intravenous alteplase in unknown onset stroke. HT was assessed on follow-up MRI or CT and diagnosed as hemorrhagic infarction type 1 and type 2 (HI1 and HI2, combined as HI), and parenchymal hemorrhage type 1 and type 2 (PH1 and PH2, combined as PH). Severity of stroke symptoms was assessed using the National Institutes of Health Stroke Scale (NIHSS) at baseline. Stroke lesion volume was measured on baseline diffusion weighted imaging (DWI). Primary endpoint was a favorable outcome defined as a modified Rankin Scale score 0–1 at 90 days.

Results: Of 483 patients included in the analysis, 95 (19.7%) showed HI and 21 (4.4%) had PH. Multiple logistic regression analysis identified treatment with alteplase (OR, 2.08 [95% CI, 1.28–3.40]), baseline NIHSS score (OR, 1.11 [95% CI, 1.05–1.17]), DWI lesion volume (OR, 1.03 [95% CI, 1.01–1.05]), baseline glucose levels (OR, 1.01 [95% CI, 1.00–1.01]) and atrial fibrillation (OR, 3.02 [95% CI, 1.57–5.80]) as predictors of any HT. The same parameters predicted HI. Predictors of PH were baseline NIHSS score (OR, 1.11 [95% CI, 1.01–1.22]) and as a trend treatment with alteplase (OR, 2.40 [95% CI, 0.93–6.96]). PH was associated with lower odds of favorable outcome (OR 0.25, 95% [CI 0.05–0.86]), while HI was not.

Conclusion: Our results indicate that HI is associated with stroke severity, cardiovascular risk factors and thrombolysis. PH is a rare complication, more frequent in severe stroke and with thrombolysis. In contrast to HI, PH is associated with worse functional outcome. The impact of HT after MRI-guided intravenous alteplase for unknown onset stroke on clinical outcome is similar as in the trials of stroke thrombolysis within a known early time-window.

Artificial intelligence for decision support in acute stroke - current roles and potential

The identification and treatment of patients with stroke is becoming increasingly complex as more treatment options become available and new relationships between disease features and treatment response are continually discovered. Consequently, clinicians must constantly learn new skills (such as clinical evaluations or image interpretation), stay up to date with the literature and incorporate advances into everyday practice. The use of artificial intelligence (AI) to support clinical decision making could reduce inter-rater variation in routine clinical practice and facilitate the extraction of vital information that could improve identification of patients with stroke, prediction of treatment responses and patient outcomes. Such support systems would be ideal for centres that deal with few patients with stroke or for regional hubs, and could assist informed discussions with the patients and their families. Moreover, the use of AI for image processing and interpretation in stroke could provide any clinician with an imaging assessment equivalent to that of an expert. However, any AI-based decision support system should allow for expert clinician interaction to enable identification of errors (for example, in automated image processing). In this Review, we discuss the increasing importance of imaging in stroke management before exploring the potential and pitfalls of AI-assisted treatment decision support in acute stroke.

Efficacy of exercise rehabilitation program accompanied by experiential music for recovery of aphasia in single cerebrovascular accidents: a randomized controlled trial

BACKGROUND

The current study aims to evaluate the effects of daily traditional experiential music listening for clinical recovery of post-stroke aphasia.

METHODS

This was a prospective randomized trial with seventy-nine stroke survivors who suffered from post-stroke aphasia. All patients underwent a neuropsychological evaluation, at time = 0 during the admission at the rehabilitation structure (baseline), and 6 months post-stroke. All cases received standard treatment for stroke and post-stroke aphasia in terms of medical care and rehabilitation. Furthermore, patients were randomized to receive either standard care only or standard care with daily traditional experiential music listening. Computer tomography perfusion and neurological examination were assessed to all patients. Recovery was measured by the score at Aachener Aphasie Test.

RESULTS

The statistically significant differences between the control group (CG) and the rest of the patients were the clinical characteristics (hemiparesis) (p = 0.002), the cerebral blood flow in affected areas (p = 0.000), and the Mini-Mental Test (mMT) (p = 0.000). Only group and mMT were independent predictor factors for recovery, according to multivariate analysis odd ratio (ΟR) (95% confidence interval) 0.022 (0.009-0.435) and 0.658 (0.142-0.224) respectively.

CONCLUSIONS

The results of this study are promising and suggest that an enriched sound environment is beneficial for patients with post-stroke aphasia since the recovery rate is higher when standard care was combined with daily music listening.

MRI for prediction of hemorrhagic transformation in acute ischemic stroke: a systematic review and meta-analysis

BACKGROUND

Hemorrhagic transformation increases mortality and morbidity in patients with acute ischemic stroke.

PURPOSE

The purpose of this study is to evaluate the diagnostic performance of magnetic resonance imaging (MRI) for prediction of hemorrhagic transformation in acute ischemic stroke.

MATERIAL AND METHODS

A systematic literature search of MEDLINE and EMBASE was performed up to 27 July 2018, including the search terms "acute ischemic stroke," "hemorrhagic transformation," and "MRI." Studies evaluating the diagnostic performance of MRI for prediction of hemorrhagic transformation in acute ischemic stroke were included. Diagnostic meta-analysis was conducted with a bivariate random-effects model to calculate the pooled sensitivity and specificity. Subgroup analysis was performed including studies using advanced MRI techniques including perfusion-weighted imaging, diffusion-weighted imaging, and susceptibility-weighted imaging.

RESULTS

Nine original articles with 665 patients were included. Hemorrhagic transformation is associated with high permeability, hypoperfusion, low apparent diffusion coefficient (ADC), and FLAIR hyperintensity. The pooled sensitivity was 82% (95% confidence interval [CI] 61-93) and the pooled specificity was 79% (95% CI 71-85). The area under the hierarchical summary receiver operating characteristic curve was 0.85 (95% CI 0.82-0.88). Although study heterogeneity was present in both sensitivity (I²=67.96%) and specificity (I²=78.93%), a threshold effect was confirmed. Studies using advanced MRI showed sensitivity of 92% (95% CI 70-98) and specificity of 78% (95% CI 65-87) to conventional MRI.

CONCLUSION

MRI may show moderate diagnostic performance for predicting hemorrhage in acute ischemic stroke although the clinical significance of this hemorrhage is somewhat uncertain.

Elevated glucose is associated with hemorrhagic transformation after mechanical thrombectomy in acute ischemic stroke patients with severe pretreatment hypoperfusion

Several pretreatment variables such as elevated glucose and hypoperfusion severity are related to brain hemorrhage after endovascular treatment of acute stroke. We evaluated whether elevated glucose and severe hypoperfusion have synergistic effects in the promotion of parenchymal hemorrhage (PH) after mechanical thrombectomy (MT). We included 258 patients MT-treated who had a pretreatment computed tomography perfusion (CTP) and a post-treatment follow-up MRI. Severe hypoperfusion was defined as regions with cerebral blood volume (CBV) values < 2.5% of normal brain [very-low CBV (VLCBV)-regions]. Median baseline glucose levels were 119 (IQR = 105-141) mg/dL. Thirty-nine (15%) patients had pretreatment VLCBV-regions, and 42 (16%) developed a PH after MT. In adjusted models, pretreatment glucose levels interacted significantly with VLCBV on the prediction of PH (p-interaction = 0.011). In patients with VLCBV-regions, higher glucose was significantly associated with PH (adjusted-OR = 3.15; 95% CI = 1.08-9.19, p = 0.036), whereas this association was not significant in patients without VLCBV-regions. CBV values measured at pretreatment CTP in coregistered regions that developed PH or infarct at follow-up were not correlated with pretreatment glucose levels, thus suggesting the existence of alternative deleterious mechanisms other than direct glucose-driven hemodynamic impairments. Overall, these results suggest that both severe hypoperfusion and glucose levels should be considered in the evaluation of adjunctive neuroprotective strategies.

Reperfusion Into Severely Damaged Brain Tissue Is Associated With Occurrence of Parenchymal Hemorrhage for Acute Ischemic Stroke

Background and Purpose: This study aims to quantify the reperfusion status within severely damaged brain tissue and to evaluate its relationship with high grade of hemorrhagic transformation (HT).

Methods: Pseudo-continuous ASL was performed along with DWI in 102 patients within 24 h post-treatments. The infarction core was identified using ADC values <550 × 10⁻⁶ mm²/s. CBF within the infarction core and its contralateral counterpart were acquired. CBF at the 25th, median, and 75th percentiles of the contralateral counterpart were used as thresholds and the ASL reperfusion volume above the threshold was labeled as vol-25, -50, and -75, respectively. Recanalization was defined according to Thrombolysis in Myocardial Infarction (TIMI) criteria.

Results: Quantified reperfusion within the infarction core differed significantly in patients with complete and incomplete recanalization. In the ROC analysis for the prediction of parenchymal hematoma (PH), ASL reperfusion vol-25 had the highest area under the curve (AUC) when compared with ASL vol-50 and ASL vol-75. ASL reperfusion vol-25 had significantly higher AUC compared with ADC threshold volume in the prediction of PH (0.783 vs. 0.685, P = 0.0036) and PH-2 (0.844 vs. 0.754, P = 0.0035). In stepwise multivariate logistic regression analysis, only ASL reperfusion vol-25 emerged as an independent predictor of PH (OR = 3.51, 95% CI: 1.65–7.45, P < 0.001) and PH-2 (OR = 2.32, 95% CI: 1.13–4.76, P = 0.022).

Conclusions: Increased reperfusion volume within severely damaged brain tissue is associated with the occurrence of higher grade of HT.

Radiological predictors of hemorrhagic transformation after acute ischemic stroke: An evidence-based analysis

Hemorrhagic transformation (HT) is one of the most common adverse events related to acute ischemic stroke (AIS) that affects the treatment plan and clinical outcome. Identification of a sensitive radiological marker may influence the controversial thrombolytic decision in the setting of AIS and may at a minimum indicate more intensive monitoring or further prophylactic interventions. In this article we summarize possible radiological biomarkers and the role of different radiological modalities including computed tomography (CT), magnetic resonance imaging, angiography, and ultrasound in predicting HT. Different radiological indices of early ischemic changes, large ischemic lesion volume, severe blood flow restriction, blood-brain barrier disruption, poor collaterals and high blood flow velocities have been reported to be associated with higher risk of HT. The current levels of evidence of the available studies highlight the role of the different CT perfusion parameters in predicting HT. Further large standardized studies are recommended to compare the sensitivity and specificity of the different radiological markers combined and delineate the most reliable predictor.

Predictors of Parenchymal Hematoma After Mechanical Thrombectomy: A Multicenter Study

Background and Purpose

Parenchymal hematoma (PH) is a rare but dreadful complication of acute ischemic stroke with unclear underlying mechanisms. We aimed to study the incidence and predictors of PH after mechanical thrombectomy.

Methods

Data from a prospective observational multicenter registry was screened to identify acute ischemic stroke patients with an anterior circulation large vessel occlusion who underwent mechanical thrombectomy. Clinical, imaging, and procedural characteristics were used for the analysis, including brain imaging systematically performed at 24 hours. PH occurrence was assessed according to ECASS (European Collaborative Acute Stroke Study) criteria. Univariate and multivariable analyses were performed to identify predictors of PH.

Results

A total of 1316 patients were included in the study. PH occurred in 153 out of 1316 patients (11.6%) and was associated with a lower rate of favorable outcome and increased mortality. On multivariable analysis, age (per 1 year increase, odds ratio [OR], 1.01; 95% CI, 1.00–1.03; P=0.05), current smoking (OR, 2.02; 95% CI, 1.32–3.09; P<0.01), admission Alberta Stroke Program Early CT Score (per a decrease of 1 point, OR, 1.70; 95% CI, 1.18–2.44; P<0.01), general anesthesia (OR, 1.98; 95% CI, 1.36–2.90; P<0.001), angiographic poor collaterals (OR, 2.13; 95% CI, 1.36–3.33; P<0.001) and embolization in new territory (OR, 2.94; 95% CI, 1.70–5.10; P<0.001) were identified as independent predictors of PH.

Conclusions

PH occurred at a rate of 11.6% after mechanical thrombectomy, with high morbidity and mortality. Our study identified clinical, radiological, and procedural predictors of PH occurrence that can serve as the focus of future periprocedural management studies with the aim of reducing its occurrence.

Reversal of Vitamin K Antagonist Therapy Before Thrombolysis for Acute Ischemic Stroke

Background and Purpose—

Acute ischemic strokes under vitamin K antagonist (VKA) treatment are not uncommon, but intravenous thrombolysis (IVT) is not recommended for international normalized ratio (INR) >1.7 because of the excess bleeding risk. However, VKA-induced anticoagulation can be easily reversed by IV infusions of 4-factor prothrombin complex concentrate bolus and vitamin K. Our pilot study aimed to determine whether IVT immediately after anticoagulation reversal could be feasible and safe in acute ischemic stroke patients under VKA with INR >1.7.

Methods—

Consecutive acute ischemic stroke patients, otherwise eligible for IVT except for VKA intake and INR >1.7, were given IVT after infusing 4-factor prothrombin complex concentrate and vitamin K. Safety and efficacy were assessed clinically and by cerebral imaging at 24 hours.

Results—

Twenty-six patients (age, 77.8±12.8 years; atrial fibrillation, 84.6%; initial National Institutes of Health Stroke Scale, 11.6±5.6) were prospectively included. INR values were 2.3±0.6 initially and 1.3±0.2, 5 minutes postreversal. No symptomatic intracranial hemorrhage or thrombotic events occurred during the first 3 days. One patient developed major systemic hemorrhoidal bleeding that required blood transfusion; 61.5% of the patients were independent (modified Rankin Scale score of ≤2) at 3 months.

Conclusions—

A reversal strategy of 4-factor prothrombin complex concentrate bolus and vitamin K before IVT could be feasible and safe in acute ischemic stroke patients under VKA with INR >1.7. Well-designed, randomized controlled trials are warranted to confirm these preliminary findings.

Optimal Delay Time of CT Perfusion for Predicting Cerebral Parenchymal Hematoma After Intra-Arterial tPA Treatment

Background and Purpose: Cerebral hemorrhage is a serious potential complication of stroke revascularization, especially in patients receiving intra-arterial tissue-type plasminogen activator (tPA) therapy. We investigated the optimal pre-intervention delay time (DT) of computed tomography perfusion (CTP) measurement to predict cerebral parenchymal hematoma (PH) in acute ischemic stroke (AIS) patients after intra-arterial tissue plasminogen activator (tPA) treatment.

Methods: The study population consisted of a series of patients with AIS who received intra-arterial tPA treatment and had CTP and follow-up computed tomography/magnetic resonance imaging (CT/MRI) to identify hemorrhagic transformation. The association of increasing DT thresholds (>2, >4, >6, >8, and >10 s) with PH was examined using receiver operating characteristic (ROC) analysis and logistic regression.

Results: Of 94 patients, 23 developed PH on follow-up imaging. Receiver operating characteristic analysis revealed that the greatest area under the curve for predicting PH occurred at DT > 4 s (area under the curve, 0.66). At this threshold of > 4 s, DT lesion volume ≥ 30.85 mL optimally predicted PH with 70% sensitivity and 59% specificity. DT > 4 s volume was independently predictive of PH in a multivariate logistic regression model (P < 0.05).

Conclusions: DT > 4 s was the parameter most strongly associated with PH. The volume of moderate, not severe, hypo-perfusion on DT is more strongly associated and may allow better prediction of PH after intra-arterial tPA thrombolysis.

The Value of Exercise Rehabilitation Program Accompanied by Experiential Music for Recovery of Cognitive and Motor Skills in Stroke Patients

BACKGROUND

The aim of this study was to systematically assess the effects of exercise rehabilitation program accompanied by experiential music for clinical recovery.

METHODS

This was a prospective randomized study with 65 stroke survivor patients. All cases underwent a neuropsychological assessment first as a prescreening test, during the admission at the Rehabilitation center (baseline), and 6 months poststroke. All patients received standard treatment for stroke in terms of medical care and rehabilitation. Additionally, all patients were separated into 2 Groups: a music Group (daily listening to experiential/traditional music), and a control Group (CG) with no experiential/traditional music therapy (standard care only). Computed tomography perfusion and full neurological examination including GCS were assessment. As Recovery was defined the improvement of cognitive and motor skills of the limb in the affected site, with an increase of muscle strength at least by 1/5 and with emotional progress.

RESULTS

Statistically significant differences were found between the Group CG and the rest of the patients in respect of Lesion size (P = .001) and CBF in affected area (P = .001). Μultivariate analysis revealed that only Group and Lesion size were independent predictors for Recovery (odd ratio [OR][95%confidence interval]) .11(.001-.133) and .798(.668-.954) respectively.

CONCLUSION

The findings of this study suggest that the music-based exercise program has a positive effect on mood profile in stroke patients and Recovery rate is higher when exercise rehabilitation program was accompanied by an enriched sound environment with experiential music.

The value of computed tomography perfusion & transcranial Doppler in early diagnosis of cerebral vasospasm in aneurysmal & traumatic subarachnoid hemorrhage

Early detection and diagnosis of cerebral vasospasm in subarachnoid hemorrhage may be challenging both on clinical and radiographic grounds. In this respect we conducted a pilot study in order to assess the feasibility of the technique in the everyday setting of a tertiary hospital and to evaluate the diagnostic performance of different diagnostic computed tomography perfusion aspects in diagnosing the clinical outcome of patients with subarachnoid hemorrhage. Receiver-operating characteristic analysis showed that a cerebral blood flow value of <24.5 presented 67% sensitivity and 100% specificity to diagnose adverse ischemic events at 1 month (p = 0.041). These case series data provide evidence that computed tomography perfusion-derived cerebral blood flow is a measurable index that may detect the degree of cerebral ischemia in a very early stage.

Early detection and diagnosis of cerebral vasospasm in subarachnoid hemorrhage is important but may be challenging both on clinical or radiographic grounds. This article provides evidence that computed tomography perfusion-derived cerebral blood flow is a measurable index that could detect the degree of cerebral ischemia in a very early stage in patients suffering with subarachnoid hemorrhage. Larger studies are needed in order to better define the role of computed tomography perfusion in early diagnosis of cerebral vasospasm.

Neuroimaging Paradigms to Identify Patients for Reperfusion Therapy in Stroke of Unknown Onset

Despite the proven efficacy of intravenous alteplase or endovascular thrombectomy for the treatment of patients with acute ischemic stroke, only a minority receive these treatments. This low treatment rate is due in large part to delay in hospital arrival or uncertainty as to the exact time of onset of ischemic stroke, which renders patients outside the current guideline-recommended window of eligibility for receiving these therapeutics. However, recent pivotal clinical trials of late-window thrombectomy now force us to rethink the value of a simplistic chronological formulation that “time is brain.” We must recognize a more nuanced concept that the rate of tissue death as a function of time is not invariant, that still salvageable tissue at risk of infarction may be present up to 24 h after last-known well, and that those patients may strongly benefit from reperfusion. Multiple studies have sought to address this clinical dilemma using neuroimaging methods to identify a radiographic time-stamp of stroke onset or evidence of salvageable ischemic tissue and thereby increase the number of patients eligible for reperfusion therapies. In this review, we provide a critical analysis of the current state of neuroimaging techniques to select patients with unwitnessed stroke for revascularization therapies and speculate on the future direction of this clinically relevant area of stroke research.

Acute Ischemic Pediatric Stroke Management: An Extended Window for Mechanical Thrombectomy?

Ischemic stroke is a rare condition to afflict the pediatric population. Congenital cardiomyopathy represents one of several possible etiologies in children. We report a 9-year-old boy who developed right middle cerebral artery stroke secondary to primary restrictive cardiomyopathy. In the absence of pediatric guidelines, the child met adult criteria for mechanical thrombectomy given the small core infarct and large penumbra. The literature suggests children may benefit from mechanical thrombectomy in carefully selected cases. Our patient exemplifies specific circumstances in which acute stroke therapy with thrombolysis and thrombectomy may be safe.

Prediction of hemorrhagic transformation after experimental ischemic stroke using MRI-based algorithms

Estimation of hemorrhagic transformation (HT) risk is crucial for treatment decision-making after acute ischemic stroke. We aimed to determine the accuracy of multiparametric MRI-based predictive algorithms in calculating probability of HT after stroke. Spontaneously, hypertensive rats were subjected to embolic stroke and, after 3 h treated with tissue plasminogen activator (Group I: n = 6) or vehicle (Group II: n = 7). Brain MRI measurements of T₂, T₂*, diffusion, perfusion, and blood-brain barrier permeability were obtained at 2, 24, and 168 h post-stroke. Generalized linear model and random forest (RF) predictive algorithms were developed to calculate the probability of HT and infarction from acute MRI data. Validation against seven-day outcome on MRI and histology revealed that highest accuracy of hemorrhage prediction was achieved with a RF-based model that included spatial brain features (Group I: area under the receiver-operating characteristic curve (AUC) = 0.85 ± 0.14; Group II: AUC = 0.89 ± 0.09), with significant improvement over perfusion- or permeability-based thresholding methods. However, overlap between predicted and actual tissue outcome was significantly lower for hemorrhage prediction models (maximum Dice's Similarity Index (DSI) = 0.20 ± 0.06) than for infarct prediction models (maximum DSI = 0.81 ± 0.06). Multiparametric MRI-based predictive algorithms enable early identification of post-ischemic tissue at risk of HT and may contribute to improved treatment decision-making after acute ischemic stroke.

Use of Noncontrast Computed Tomography and Computed Tomographic Perfusion in Predicting Intracerebral Hemorrhage After Intravenous Alteplase Therapy

Background and Purpose—

Intracerebral hemorrhage is a feared complication of intravenous alteplase therapy in patients with acute ischemic stroke. We explore the use of multimodal computed tomography in predicting this complication.

Methods—

All patients were administered intravenous alteplase with/without intra-arterial therapy. An age- and sex-matched case–control design with classic and conditional logistic regression techniques was chosen for analyses. Outcome was parenchymal hemorrhage on 24- to 48-hour imaging. Exposure variables were imaging (noncontrast computed tomography hypoattenuation degree, relative volume of very low cerebral blood volume, relative volume of cerebral blood flow ≤7 mL/min·per 100 g, relative volume of T max ≥16 s with all volumes standardized to z axis coverage, mean permeability surface area product values within T max ≥8 s volume, and mean permeability surface area product values within ipsilesional hemisphere) and clinical variables (NIHSS [National Institutes of Health Stroke Scale], onset to imaging time, baseline systolic blood pressure, blood glucose, serum creatinine, treatment type, and reperfusion status).

Results—

One-hundred eighteen subjects (22 patients with parenchymal hemorrhage versus 96 without, median baseline NIHSS score of 15) were included in the final analysis. In multivariable regression, noncontrast computed tomography hypoattenuation grade ( P <0.006) and computerized tomography perfusion white matter relative volume of very low cerebral blood volume ( P =0.04) were the only significant variables associated with parenchymal hemorrhage on follow-up imaging (area under the curve, 0.73; 95% confidence interval, 0.63–0.83). Interrater reliability for noncontrast computed tomography hypoattenuation grade was moderate (κ=0.6).

Conclusions—

Baseline hypoattenuation on noncontrast computed tomography and very low cerebral blood volume on computerized tomography perfusion are associated with development of parenchymal hemorrhage in patients with acute ischemic stroke receiving intravenous alteplase.

Predictive Value of RAPID Assessed Perfusion Thresholds on Final Infarct Volume in SWIFT PRIME (Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment)

BACKGROUND AND PURPOSE

Computed tomography perfusion imaging can estimate the size of the ischemic core, which can be used for the selection of patients for endovascular therapy. The relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) thresholds chosen to identify ischemic core influence the accuracy of prediction. We aimed to analyze the accuracy of various rCBV and rCBF thresholds for predicting the 27-hour infarct volume using RAPID automated analysis software from the SWIFT PRIME trial (Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment) data.

METHODS

Patients from the SWIFT PRIME study who achieved complete reperfusion based on time until the residue function reached its peak >6 s perfusion maps obtained at 27 hours were included. Patients from both the intravenous tissue-type plasminogen activator only and endovascular groups were included in analysis. Final infarct volume was determined on magnetic resonance imaging (fluid-attenuated inversion recovery images) or computed tomography scans obtained 27 hours after symptom onset. The predicted ischemic core volumes on rCBV and rCBF maps using thresholds ranging between 0.2 and 0.8 were compared with the actual infarct volume to determine the most accurate thresholds.

RESULTS

Among the 47 subjects, the following baseline computed tomography perfusion thresholds most accurately predicted the actual 27-hour infarct volume: rCBV=0.32, median absolute error (MAE)=9 mL; rCBV=0.34, MAE=9 mL; rCBF=0.30, MAE=8.8 mL; rCBF=0.32, MAE=7 mL; and rCBF=0.34, MAE=7.3.

CONCLUSIONS

Brain regions with rCBF 0.30 to 0.34 or rCBV 0.32 to 0.34 thresholds provided the most accurate prediction of infarct volume in patients who achieved complete reperfusion with MAEs of ≤9 mL.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01657461.

Multiparametric Magnetic Resonance Imaging for Prediction of Parenchymal Hemorrhage in Acute Ischemic Stroke After Reperfusion Therapy

Background and Purpose—

Patients with acute ischemic stroke are at increased risk of developing parenchymal hemorrhage (PH), particularly in the setting of reperfusion therapies. We have developed a predictive model to examine the risk of PH using combined magnetic resonance perfusion and diffusion parameters, including cerebral blood volume (CBV), apparent diffusion coefficient, and microvascular permeability (K2).

Methods—

Voxel-based values of CBV, K2, and apparent diffusion coefficient from the ischemic core were obtained using pretreatment magnetic resonance imaging data from patients enrolled in the MR RESCUE clinical trial (Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy). The associations between PH and extreme values of imaging parameters were assessed in univariate and multivariate analyses. Receiver-operating characteristic curve analysis was performed to determine the optimal parameter(s) and threshold for predicting PH.

Results—

In 83 patients included in this analysis, 20 developed PH. Univariate analysis showed significantly lower 10th percentile CBV and 10th percentile apparent diffusion coefficient values and significantly higher 90th percentile K2 values within the infarction core of patients with PH. Using classification tree analysis, the 10th percentile CBV at threshold of 0.47 and 90th percentile K2 at threshold of 0.28 resulted in overall predictive accuracy of 88.7%, sensitivity of 90.0%, and specificity of 87.3%, which was superior to any individual or combination of other classifiers.

Conclusions—

Our results suggest that combined 10th percentile CBV and 90th percentile K2 is an independent predictor of PH in patients with acute ischemic stroke with diagnostic accuracy superior to individual classifiers alone. This approach may allow risk stratification for patients undergoing reperfusion therapies.

Clinical Trial Registration—

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00389467.

Brain hemorrhage after endovascular reperfusion therapy of ischemic stroke: a threshold-finding whole-brain perfusion CT study

Endovascular reperfusion therapy is increasingly used for acute ischemic stroke treatment. The occurrence of parenchymal hemorrhage is clinically relevant and increases with reperfusion therapies. Herein we aimed to examine the optimal perfusion CT-derived parameters and the impact of the duration of brain ischemia for the prediction of parenchymal hemorrhage after endovascular therapy. A cohort of 146 consecutive patients with anterior circulation occlusions and treated with endovascular reperfusion therapy was analyzed. Recanalization was assessed at the end of reperfusion treatment, and the rate of parenchymal hemorrhage at follow-up neuroimaging. In regression analyses, cerebral blood volume and cerebral blood flow performed better than Delay Time maps for the prediction of parenchymal hemorrhage. The most informative thresholds (receiver operating curves) for relative cerebral blood volume and relative cerebral blood flow were values lower than 2.5% of normal brain. In binary regression analyses, the volume of regions with reduced relative cerebral blood volume and/or relative cerebral blood flow was significantly associated with an increased risk of parenchymal hemorrhage, as well as delayed vessel recanalization. These results highlight the relevance of the severity and duration of ischemia as drivers of blood-brain barrier disruption in acute ischemic stroke and support the role of perfusion CT for the prediction of parenchymal hemorrhage.

Severe cerebral hypovolemia on perfusion CT and lower body weight are associated with parenchymal haemorrhage after thrombolysis

INTRODUCTION

Haemorrhagic transformation of acute ischemic stroke (AIS) and particularly parenchymal haemorrhage (PH) remains a feared complication of intravenous thrombolysis (IVT). We aimed to identify clinical and perfusion CT (PCT) variables which are independently associated with PHs.

METHODS

In this observational cohort study, based on the Acute Stroke Registry Analysis of Lausanne (ASTRAL) from 2003 to December 2013, we selected patients with AIS involving the middle cerebral artery (MCA) territory who were thrombolysed within 4.5 h of symptoms' onset and who had a good quality baseline PCT at the beginning of IVT. In addition to demographic, clinical, laboratory and non-contrast CT data, volumes of salvageable tissue and ischemic core on PCT, as well as absolute CBF and CBV values within the ischemic regions were compared in patients with and without PH in multivariate analysis.

RESULTS

Of the 190 included patients, 24 (12.6%) presented a PH (11 had PH1 and 13 had PH2). In multivariate analysis of the clinical and radiological variables, the lowest CBV in the core and lower body weight was both significantly associated with PH (p = 0.009 and p = 0.024, respectively).

CONCLUSION

In thrombolysed MCA strokes, maximal hypoperfusion severity depicted by lowest CBV values in the core region and lower body weight are independently correlated with PH. This information, if confirmed in other case series, may add to the stratification of revascularisation decisions in patients with a perceived high PH risk.

Impact of Slow Blood Filling via Collaterals on Infarct Growth: Comparison of Mismatch and Collateral Status

Background and Purpose

Perfusion-diffusion mismatch has been evaluated to determine whether the presence of a target mismatch helps to identify patients who respond favorably to recanalization therapies. We compared the impact on infarct growth of collateral status and the presence of a penumbra, using magnetic resonance perfusion (MRP) techniques.

Methods

Consecutive patients who were candidates for recanalization therapy and underwent serial diffusion-weighted imaging (DWI) and MRP were enrolled. A collateral flow map derived from MRP source data was generated by automatic post-processing. The impact of a target mismatch (Tmax>6 s/apparent diffusion coefficient (ADC) volume≥1.8, ADC volume<70 mL; and Tmax>10 s for ADC volume<100 mL) on infarct growth was compared with MR-based collateral grading on day 7 DWI, using multivariate linear regression analysis.

Results

Among 73 patients, 55 (75%) showed a target mismatch, whereas collaterals were poor in 14 (19.2%), intermediate in 36 (49.3%), and good in 23 (31.5%) patients. After adjusting for initial severity of stroke, early recanalization (P<0.001) and the MR-based collateral grading (P=0.001), but not the presence of a target mismatch, were independently associated with infarct growth. Even in patients with a target mismatch and successful recanalization, the degree of infarct growth depended on the collateral status. Perfusion status at later Tmax time points (beyond the arterial phase) was more closely correlated with collateral status.

Conclusions

Patients with good collaterals show a favorable outcome in terms of infarct growth, regardless of the presence of a target mismatch pattern. The presence of slow blood filling predicts collateral status and infarct growth.

Mismatch of Low Perfusion and High Permeability Predicts Hemorrhagic Transformation Region in Acute Ischemic Stroke Patients Treated with Intra-arterial Thrombolysis

This study sought to determine whether the permeability related parameter K(trans), derived from computed tomography perfusion (CTP) imaging, can predict hemorrhagic transformation (HT) in patients with acute ischemic stroke who receive intra-arterial thrombolysis. Data from patients meeting the criterion were examined. CTP was performed and K(trans) maps were used to assess the permeability values in HT and non-HT regions. A receiver operating characteristic (ROC) curve was calculated, showing the sensitivity and specificity of K(trans) for predicting HT risk. Composite images were produced to illustrate the spatial correlations among perfusion, permeability changes and HT. This study examined 41 patients. Twenty-six patients had hemorrhagic infarction and 15 had parenchymal hemorrhage. The mean K(trans) value in HT regions was significantly lower than that in the non-HT regions (0.26 ± 0.21/min vs. 0.78 ± 0.64/min; P < 0.001). The ROC curve analysis identified an optimal cutoff value of 0.334/min for K(trans) to predict HT risk. Composite images suggested ischemic regions with low permeability, or the mismatch area of low perfusion and high permeability, more likely have HT. HT regions after intra-arterial thrombolysis had lower permeability values on K(trans) maps. The mismatch area of lower perfusion and higher permeability are more likely to develop HT.

Interaction of Recanalization, Intracerebral Hemorrhage, and Cerebral Edema After Intravenous Thrombolysis

BACKGROUND AND PURPOSE

Both intracerebral hemorrhage (ICH) and brain edema have been attributed to reperfusion after intravenous thrombolysis. We explored the interaction of recanalization and core size for imaging outcomes (ICH and vasogenic brain edema).

METHODS

In patients with anterior circulation occlusion given intravenous thrombolysis <4.5 hours and imaged with computed tomographic (CT) perfusion and CT angiography, we defined volumes of core (relative delay time >2 s and relative cerebral blood flow <40%) and penumbra (relative delay time >2 s). CT and CT angiography at 24 hours were reviewed for ICH (European Cooperative Acute Stroke Study [ECASS]-2 definition), early vasogenic edema (third International Stroke Trial [IST-3] criteria), and recanalization (thrombolysis in myocardial infarction 2-3). Independent effects of recanalization, core volume and potential interactions on edema, ICH and day 90 outcomes were estimated by logistic regression.

RESULTS

In 123 patients, there was a trend for recanalization to be associated with H1/2 ICH (odds ratio [OR], 2.3 [0.97-5.5]; P=0.06) but not with PH1/2 ICH (OR, 1.7 [0.33-8.8]; P=0.5), any edema, or significant brain edema (OR, 1.45 [0.4-4.9]; P=0.55). Ischemic core (>50 mL) was associated with any ICH (OR, 4.0 [1.6-9.5]; P=0.003), edema (OR, 5.4 [2-14]; P<0.01), and significant brain edema (OR, 17.4 [5.3-57]; P<0.01) but not with PH1/2 ICH (OR, 1.2 [0.23-6.5]; P=0.8), after controlling for recanalization. There was no significant interaction of recanalization and large core for any adverse outcomes.

CONCLUSIONS

Large ischemic core was associated with poorer outcomes and both early vasogenic brain edema and ICH, but recanalization on 24-hour CT angiography was associated with clinically favorable outcome. There was no significant interaction of recanalization and large core volume for any outcomes. The association of hemorrhage or brain edema with post-thrombolysis reperfusion is unclear.

Global White Matter Hypoperfusion on CT Predicts Larger Infarcts and Hemorrhagic Transformation after Acute Ischemia

INTRODUCTION

Presence of white matter hyperintensity (WMH) on MRI is a marker of cerebral small vessel disease and is associated with increased small vessel stroke and increased risk of hemorrhagic transformation (HT) after thrombolysis.

AIM

We sought to determine whether white matter hypoperfusion (WMHP) on perfusion CT (CTP) was related to WMH, and if WMHP predisposed to acute lacunar stroke subtype and HT after thrombolysis.

METHODS

Acute ischemic stroke patients within 12 h of symptom onset at 2 centers were prospectively recruited between 2011 and 2013 for the International Stroke Perfusion Imaging Registry. Participants routinely underwent baseline CT imaging, including CTP, and follow-up imaging with MRI at 24 h.

RESULTS

Of 229 ischemic stroke patients, 108 were Caucasians and 121 Chinese. In the contralateral white matter, patients with acute lacunar stroke had lower cerebral blood flow (CBF) and cerebral blood volume (CBV), compared to those with other stroke subtypes (P = 0.041). There were 46 patients with HT, and WMHP was associated with increased risk of HT (R(2) = 0.417, P = 0.002). Compared to previously reported predictors of HT, WMHP performed better than infarct core volume (R(2) = 0.341, P = 0.034), very low CBV volume (R(2) = 0.249, P = 0.026), and severely delayed perfusion (Tmax>14 second R(2) = 0.372, P = 0.011). Patients with WMHP also had larger acute infarcts and increased infarct growth compared to those without WMHP (mean 28 mL vs. 13 mL P < 0.001).

CONCLUSION

White matter hypoperfusion remote to the acutely ischemic region on CTP is a marker of small vessel disease and was associated with increased HT, larger acute infarct cores, and greater infarct growth.

Imaging Paradigms in Acute Ischemic Stroke: A Pragmatic Evidence-based Approach

Online supplemental material is available for this article.

[Neurovisualisation predictors of malignant cerebral infarction and hemorrhagic transformation]

Neuroimaging plays a central role in the assessment of patients with acute ischemic stroke. Within a few minutes, modern multimodal imaging protocols can provide one with comprehensive information about prognosis, management, and outcome of the disease, and may detect changes in the intracranial structures reflecting severity of the ischemic injury depicted by four Ps: parenchyma (of the brain), pipes (i.e., the cerebral blood vessels), penumbra, and permeability (of the blood brain barrier). In this article, we have reviewed neuroradiological predictors of malignant middle cerebral artery infarction and hemorrhagic transformation in light of the aforementioned four Ps.

Reperfusion of very low cerebral blood volume lesion predicts parenchymal hematoma after endovascular therapy

BACKGROUND AND PURPOSE

Ischemic stroke patients with regional very low cerebral blood volume (VLCBV) on baseline imaging have increased risk of parenchymal hemorrhage (PH) after intravenous alteplase-induced reperfusion. We developed a method for automated detection of VLCBV and examined whether patients with reperfused-VLCBV are at increased risk of PH after endovascular reperfusion therapy.

METHODS

Receiver operating characteristic analysis was performed to optimize a relative CBV threshold associated with PH in patients from the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution 2 (DEFUSE 2) study. Regional reperfused-VLCBV was defined as regions with low relative CBV on baseline imaging that demonstrated normal perfusion (Tmax <6 s) on coregistered early follow-up magnetic resonance imaging. The association between VLCBV, regional reperfused-VLCBV and PH was assessed in univariate and multivariate analyses.

RESULTS

In 91 patients, the greatest area under the curve for predicting PH occurred at an relative CBV threshold of <0.42 (area under the curve, 0.77). At this threshold, VLCBV lesion volume ≥3.55 mL optimally predicted PH with 94% sensitivity and 63% specificity. Reperfused-VLCBV lesion volume was more specific (0.74) and equally sensitive (0.94). In total, 18 patients developed PH, of whom 17 presented with VLCBV (39% versus 2%; P=0.001), all of them had regional reperfusion (47% versus 0%; P=0.01), and 71% received intravenous alteplase. VLCBV lesion (odds ratio, 33) and bridging with intravenous alteplase (odds ratio, 3.8) were independently associated with PH. In a separate model, reperfused-VLCBV remained the single independent predictor of PH (odds ratio, 53).

CONCLUSIONS

These results suggest that VLCBV can be used for risk stratification of patients scheduled to undergo endovascular therapy in trials and routine clinical practice.

Perfusion computed tomography to assist decision making for stroke thrombolysis

The use of perfusion imaging to guide selection of patients for stroke thrombolysis remains controversial because of lack of supportive phase three clinical trial evidence. We aimed to measure the outcomes for patients treated with intravenous recombinant tissue plasminogen activator (rtPA) at a comprehensive stroke care facility where perfusion computed tomography was routinely used for thrombolysis eligibility decision assistance. Our overall hypothesis was that patients with 'target' mismatch on perfusion computed tomography would have improved outcomes with rtPA. This was a prospective cohort study of consecutive ischaemic stroke patients who fulfilled standard clinical/non-contrast computed tomography eligibility criteria for treatment with intravenous rtPA, but for whom perfusion computed tomography was used to guide the final treatment decision. The 'real-time' perfusion computed tomography assessments were qualitative; a large perfusion computed tomography ischaemic core, or lack of significant perfusion lesion-core mismatch were considered relative exclusion criteria for thrombolysis. Specific volumetric perfusion computed tomography criteria were not used for the treatment decision. The primary analysis compared 3-month modified Rankin Scale in treated versus untreated patients after 'off-line' (post-treatment) quantitative volumetric perfusion computed tomography eligibility assessment based on presence or absence of 'target' perfusion lesion-core mismatch (mismatch ratio >1.8 and volume >15 ml, core <70 ml). In a second analysis, we compared outcomes of the perfusion computed tomography-selected rtPA-treated patients to an Australian historical cohort of non-contrast computed tomography-selected rtPA-treated patients. Of 635 patients with acute ischaemic stroke eligible for rtPA by standard criteria, thrombolysis was given to 366 patients, with 269 excluded based on visual real-time perfusion computed tomography assessment. After off-line quantitative perfusion computed tomography classification: 253 treated patients and 83 untreated patients had 'target' mismatch, 56 treated and 31 untreated patients had a large ischaemic core, and 57 treated and 155 untreated patients had no target mismatch. In the primary analysis, only in the target mismatch subgroup did rtPA-treated patients have significantly better outcomes (odds ratio for 3-month, modified Rankin Scale 0-2 = 13.8, P < 0.001). With respect to the perfusion computed tomography selected rtPA-treated patients (n = 366) versus the clinical/non-contrast computed tomography selected rtPA-treated patients (n = 396), the perfusion computed tomography selected group had higher adjusted odds of excellent outcome (modified Rankin Scale 0-1 odds ratio 1.59, P = 0.009) and lower mortality (odds ratio 0.56, P = 0.021). Although based on observational data sets, our analyses provide support for the hypothesis that perfusion computed tomography improves the identification of patients likely to respond to thrombolysis, and also those in whom natural history may be difficult to modify with treatment.

MRI-guided selection of patients for treatment of acute ischemic stroke

PURPOSE OF REVIEW

To summarize what is known about the use of MRI in acute stroke treatment (predominantly thrombolysis), to examine the assumptions and theories behind the interpretation of magnetic resonance images of acute ischemic stroke and how they are used to select patients for therapies, and to suggest directions for future research.

RECENT FINDINGS

Recent studies have been contradictory about the usefulness of MRI in selecting patients for treatment. New MRI models for selecting patients have emerged that focus not only on the ischemic penumbra but also on the infarct core. Fixed time-window selection parameters are being replaced by timing-based individualized MRI stroke features. New ways to interpret traditional MRI stroke sequences are emerging.

SUMMARY

Although the efficacy of acute stroke treatment is time dependent, the use of fixed time windows cannot account for individual differences in infarct evolution, which could potentially be detected with MRI. Although MRI shows promise for identifying patients who should be treated, as well as excluding patients who should not be treated, definitive evidence is still lacking. Future research should focus on validating the use of MRI to select patients for intravenous therapies in extended time windows.

Acute blood pressure reduction in patients with intracerebral hemorrhage does not result in borderzone region hypoperfusion

BACKGROUND AND PURPOSE

The Intracerebral Hemorrhage Acutely Decreasing Arterial Pressure Trial (ICH ADAPT) demonstrated blood pressure (BP) reduction does not affect mean perihematoma or hemispheric cerebral blood flow. Nonetheless, portions of the perihematoma and borderzones may reach ischemic thresholds after BP reduction. We tested the hypothesis that BP reduction after intracerebral hemorrhage results in increased critically hypoperfused tissue volumes.

METHODS

Patients with Intracerebral hemorrhage were randomized to a target systolic BP (SBP) of <150 or <180 mm Hg and imaged with computed tomographic perfusion 2 hours later. The volumes of tissue below cerebral blood flow thresholds for ischemia (<18 mL/100 g/min) and infarction (<12 mL/100 g/min) were calculated as a percentage of the total volume within the internal and external borderzones and the perihematoma region.

RESULTS

Seventy-five patients with intracerebral hemorrhage were randomized a median (interquartile range) of 7.8 (13.3) hours from onset. Acute hematoma volume was 17.8 (27.1) mL and mean SBP was 183±22 mm Hg. At the time of computed tomographic perfusion (2.3 [1.0] hours after randomization), SBP was lower in the <150 mm Hg (n=37; 140±18 mm Hg) than in the <180 mm Hg group (n=36; 162±12 mm Hg; P<0.001). BP treatment did not affect the percentage of total borderzone tissue with cerebral blood flow<18 (14.7±13.6 versus 15.6±13.7%; P=0.78) or <12 mL/100 g/min (5.1±5.1 versus 5.8±6.8%; P=0.62). Similar results were found in the perihematoma region. Low SBP load (fraction of time with SBP<150 mmHg) did not predict borderzone tissue volume with cerebral blood flow<18 mL/100 g/min (β=0.023 [-0.073, 0.119]).

CONCLUSIONS

BP reduction does not increase the volume of critically hypoperfused borderzone or perihematoma tissue. These data support the safety of early BP reduction in intracerebral hemorrhage.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00963976.

Thrombolysis for acute ischaemic stroke

BACKGROUND

Most strokes are due to blockage of an artery in the brain by a blood clot. Prompt treatment with thrombolytic drugs can restore blood flow before major brain damage has occurred and improve recovery after stroke in some people. Thrombolytic drugs, however, can also cause serious bleeding in the brain, which can be fatal. One drug, recombinant tissue plasminogen activator (rt-PA), is licensed for use in selected patients within 4.5 hours of stroke in Europe and within three hours in the USA. There is an upper age limit of 80 years in some countries, and a limitation to mainly non-severe stroke in others. Forty per cent more data are available since this review was last updated in 2009.

OBJECTIVES

To determine whether, and in what circumstances, thrombolytic therapy might be an effective and safe treatment for acute ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched November 2013), MEDLINE (1966 to November 2013) and EMBASE (1980 to November 2013). We also handsearched conference proceedings and journals, searched reference lists and contacted pharmaceutical companies and trialists.

SELECTION CRITERIA

Randomised trials of any thrombolytic agent compared with control in people with definite ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors applied the inclusion criteria, extracted data and assessed trial quality. We verified the extracted data with investigators of all major trials, obtaining additional unpublished data if available.

MAIN RESULTS

We included 27 trials, involving 10,187 participants, testing urokinase, streptokinase, rt-PA, recombinant pro-urokinase or desmoteplase. Four trials used intra-arterial administration, while the rest used the intravenous route. Most data come from trials that started treatment up to six hours after stroke. About 44% of the trials (about 70% of the participants) were testing intravenous rt-PA. In earlier studies very few of the participants (0.5%) were aged over 80 years; in this update, 16% of participants are over 80 years of age due to the inclusion of IST-3 (53% of participants in this trial were aged over 80 years). Trials published more recently utilised computerised randomisation, so there are less likely to be baseline imbalances than in previous versions of the review. More than 50% of trials fulfilled criteria for high-grade concealment; there were few losses to follow-up for the main outcomes.Thrombolytic therapy, mostly administered up to six hours after ischaemic stroke, significantly reduced the proportion of participants who were dead or dependent (modified Rankin 3 to 6) at three to six months after stroke (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.78 to 0.93). Thrombolytic therapy increased the risk of symptomatic intracranial haemorrhage (OR 3.75, 95% CI 3.11 to 4.51), early death (OR 1.69, 95% CI 1.44 to 1.98; 13 trials, 7458 participants) and death by three to six months after stroke (OR 1.18, 95% CI 1.06 to 1.30). Early death after thrombolysis was mostly attributable to intracranial haemorrhage. Treatment within three hours of stroke was more effective in reducing death or dependency (OR 0.66, 95% CI 0.56 to 0.79) without any increase in death (OR 0.99, 95% CI 0.82 to 1.21; 11 trials, 2187 participants). There was heterogeneity between the trials. Contemporaneous antithrombotic drugs increased the risk of death. Trials testing rt-PA showed a significant reduction in death or dependency with treatment up to six hours (OR 0.84, 95% CI 0.77 to 0.93, P = 0.0006; 8 trials, 6729 participants) with significant heterogeneity; treatment within three hours was more beneficial (OR 0.65, 95% CI 0.54 to 0.80, P < 0.0001; 6 trials, 1779 participants) without heterogeneity. Participants aged over 80 years benefited equally to those aged under 80 years, particularly if treated within three hours of stroke.

AUTHORS' CONCLUSIONS

Thrombolytic therapy given up to six hours after stroke reduces the proportion of dead or dependent people. Those treated within the first three hours derive substantially more benefit than with later treatment. This overall benefit was apparent despite an increase in symptomatic intracranial haemorrhage, deaths at seven to 10 days, and deaths at final follow-up (except for trials testing rt-PA, which had no effect on death at final follow-up). Further trials are needed to identify the latest time window, whether people with mild stroke benefit from thrombolysis, to find ways of reducing symptomatic intracranial haemorrhage and deaths, and to identify the environment in which thrombolysis may best be given in routine practice.

The role of advanced neuroimaging in intracerebral hemorrhage

In this report, the authors sought to summarize existing literature to provide an overview of the currently available techniques and to critically assess the evidence for or against their application in intracerebral hemorrhage (ICH) for management, prognostication, and research. Functional imaging in ICH represents a potential major step forward in the ability of physicians to assess patients suffering from this devastating illness due to the advantages over standing imaging modalities focused on general tissue structure alone, but its use is highly controversial due to the relative paucity of literature and the lack of consolidation of the predominantly small data sets that are currently in existence. Current data support that diffusion tensor imaging and tractography, diffusion-perfusion weighted MRI techniques, and functional MRI all possess major potential in the areas of highlighting motor deficits, motor recovery, and network reorganization. Novel clinical studies designed to objectively assess the value of each of these modalities on a wider scale in conjunction with other methods of investigation and management will allow for their rapid incorporation into standard practice.