Early infarct growth predicts long-term clinical outcome in ischemic stroke

Predicting Penumbra Salvage and Infarct Growth in Acute Ischemic Stroke: A Multifactor Survival Game

BACKGROUND

Effective treatment of acute ischemic stroke requires reperfusion of salvageable tissue. We investigated the predictors of penumbra salvage (PS) and infarct growth (IG) in a large cohort of stroke patients.

METHODS

In the ASTRAL registry from 2003 to 2016, we selected middle cerebral artery strokes <24 h with a high-quality CT angiography and CT perfusion. PS and IG were correlated in multivariate analyses with clinical, biochemical and radiological variables, and with clinical outcomes.

RESULTS

Among 4090 patients, 551 were included in the study, 50.8% male, mean age (±SD) 66.3 ± 14.7 years, mean admission NIHSS (±SD 13.3 ± 7.1) and median onset-to-imaging-time (IQR) 170 (102 to 385) minutes. Increased PS was associated with the following: higher BMI and lower WBC; neglect; larger penumbra; absence of early ischemic changes, leukoaraiosis and other territory involvement; and higher clot burden score. Reduced IG was associated with the following: non-smokers; lower glycemia; larger infarct core; absence of early ischemic changes, chronic vascular brain lesions, other territory involvement, extracranial arterial pathology and hyperdense middle cerebral artery sign; and higher clot burden score. When adding subacute variables, recanalization was associated with increased PS and reduced IG, and the absence of haemorrhage with reduced IG. Collateral status was not significantly associated with IG nor with PS. Increased PS and reduced IG correlated with better 3- and 12-month outcomes.

CONCLUSION

In our comprehensive analysis, multiple factors were found to be responsible for PS or IG, the strongest being radiological features. These findings may help to better select patients, particularly for more aggressive or late acute stroke treatment.

Predictive Value of Different Computed Tomography Perfusion Software Regarding 90-Day Outcome of Acute Ischemic Stroke Patients After Endovascular Treatment: A Comparison With Magnetic Resonance Imaging

OBJECTIVE

This study compared ischemic core and penumbra volumes obtained using different computed tomography perfusion (CTP) software and evaluated the predictive value of CTP and magnetic resonance imaging (MRI) results for 90-day outcomes.

METHODS

In total, 105 acute ischemic stroke patients who underwent endovascular treatment from January 2016 to December 2020 were included. Patients were divided into good and poor outcome groups by a modified Rankin Scale score. Computed tomography perfusion core and penumbra volumes were obtained using OleaSphere and Vitrea software to assess the volumetric relationship with MRI using the Spearman correlation test, intraclass correlation coefficient (ICC), and Bland-Altman plot. Three multivariable models were developed: baseline variables with MRI infarct volume, baseline variables with OleaSphere core volume, and baseline variables with Vitrea core volume. The area under the receiver operating characteristic curve of the 3 models was compared using the DeLong test.

RESULTS

Median core volumes were 27.5, 26.9, and 31.1 mL for OleaSphere, Vitrea, and MRI, respectively. There was substantial correlation and excellent agreement between OleaSphere and MRI core volume ( ρ = 0.84, P < 0.001; ICC = 0.84) and Vitrea and MRI core volume ( ρ = 0.80, P < 0.001; ICC = 0.83). The areas under curve for MRI volume, OleaSphere, and Vitrea were 0.86, 0.84, and 0.83, respectively. There were no significant differences ( P = 0.18) between the predictive value of the 3 models.

CONCLUSIONS

Computed tomography perfusion core volumes showed substantial correlation and excellent agreement with MRI. There was no significant difference in the predictive value of the 3 models, suggesting that core volumes measured using CTP software can predict patient prognosis.

Multiplexed mRNA analysis of brain-derived extracellular vesicles upon experimental stroke in mice reveals increased mRNA content with potential relevance to inflammation and recovery processes

Extracellular vesicles (EVs) are lipid bilayer-enclosed structures that represent newly discovered means for cell-to-cell communication as well as promising disease biomarkers and therapeutic tools. Apart from proteins, lipids, and metabolites, EVs can deliver genetic information such as mRNA, eliciting a response in the recipient cells. In the present study, we have analyzed the mRNA content of brain-derived EVs (BDEVs) isolated 72 h after experimental stroke in mice and compared them to controls (shams) using nCounter^® Nanostring panels, with or without prior RNA isolation. We found that both panels show similar results when comparing upregulated mRNAs in stroke. Notably, the highest upregulated mRNAs were related to processes of stress and immune system responses, but also to anatomical structure development, cell differentiation, and extracellular matrix organization, thus indicating that regenerative mechanisms already take place at this time-point. The five top overrepresented mRNAs in stroke mice were confirmed by RT-qPCR and, interestingly, found to be full-length. We could reveal that the majority of the mRNA cargo in BDEVs was of microglial origin and predominantly present in small BDEVs (≤ 200 nm in diameter). However, the EV population with the highest increase in the total BDEVs pool at 72 h after stroke was of oligodendrocytic origin. Our study shows that nCounter^® panels are a good tool to study mRNA content in tissue-derived EVs as they can be carried out even without previous mRNA isolation, and that the mRNA cargo of BDEVs indicates a possible participation in inflammatory but also recovery processes after stroke.

Treatment Efficacy Analysis in Acute Ischemic Stroke Patients Using In Silico Modeling Based on Machine Learning: A Proof-of-Principle

Interventional neuroradiology is characterized by engineering- and experience-driven device development with design improvements every few months. However, clinical validation of these new devices requires lengthy and expensive randomized controlled trials. This contribution proposes a machine learning-based in silico study design to evaluate new devices more quickly with a small sample size. Acute diffusion- and perfusion-weighted MRI, segmented one-week follow-up imaging, and clinical variables were available for 90 acute ischemic stroke patients. Three treatment option-specific random forest models were trained to predict the one-week follow-up lesion segmentation for (1) patients successfully recanalized using intra-arterial mechanical thrombectomy, (2) patients successfully recanalized using intravenous thrombolysis, and (3) non-recanalizing patients as an analogue for conservative treatment for each patient in the sample, independent of the true group membership. A repeated-measures analysis of the three predicted follow-up lesions for each patient revealed significantly larger lesions for the non-recanalizing group compared to the successful intravenous thrombolysis treatment group, which in turn showed significantly larger lesions compared to the successful mechanical thrombectomy treatment group (p < 0.001). A groupwise comparison of the true follow-up lesions for the three treatment options showed the same trend but did not reach statistical significance (p = 0.19). We conclude that the proposed machine learning-based in silico trial design leads to clinically feasible results and can support new efficacy studies by providing additional power and potential early intermediate results.

Modeling and simulation to predict the degree of disability over time in acute ischemic stroke patients

Disability in patients with acute stroke varies over time, with the prediction of outcomes being critical for proper management. This study aimed to develop a model to predict the cumulative probability of each modified Rankin Scale (mRS) score over time with inclusion of significant covariates. Longitudinal data obtained from 193 patients, 1–24 months after onset of acute ischemic stroke, were included for a modeling analysis using nonlinear mixed‐effect modeling (NONMEM). After selecting a model that best described the time course of the probability of different mRS scores, potential covariates were tested. Visual predicted check plots, parameter estimates, and decreases in minimum objective function values were used for model evaluation. The inclusion of disease progression (DP) in the baseline proportional odds cumulative logit model significantly improved the model compared to the baseline model without DP. An inhibitory maximum effect (E_max) model was determined to be the best DP model for describing the probability of specific mRS scores over time. In the final model, DP was multiplied with the baseline cumulative logit probability with a baseline adjustment. In addition to differences in lesion volume (DLV), the final model included comorbid diabetes mellitus (DM) and baseline National Institutes of Health Stroke Scale (NIHSS) scores on E_max as statistically significant covariates. This study developed a model including DLV, NIHSS score, and comorbid DM for predicting the disability time course in patients with acute ischemic stroke. This model may help to predict disease outcomes and to develop more appropriate management plans for patients with acute stroke.

Effect of In-Hospital Remote Ischemic Perconditioning on Brain Infarction Growth and Clinical Outcomes in Patients With Acute Ischemic Stroke: The RESCUE BRAIN Randomized Clinical Trial

Importance

Treatment with remote ischemic perconditioning has been reported to reduce brain infarction volume in animal models of stroke. Whether this neuroprotective effect was observed in patients with acute ischemic stroke remains unknown.

Objective

To determine whether treatment with remote ischemic perconditioning administered to the leg of patients with acute ischemic stroke can reduce brain infarction volume growth.

Design, Setting, and Participants

This proof-of-concept multicenter prospective randomized open-label with blinded end point clinical trial was performed from January 12, 2015, to May 2, 2018. Patients were recruited from 11 stroke centers in France. Of the 188 patients who received magnetic resonance imaging within 6 hours of symptom onset and were confirmed to have carotid ischemic stroke, 93 were randomized to receive treatment with lower-limb remote ischemic perconditioning in addition to standard care (the intervention group), and 95 were randomized to receive standard care alone (the control group).

Interventions

Randomization on a 1:1 ratio to receive treatment with remote ischemic perconditioning (4 cycles of 5-minute inflations and 5-minute deflations to the thigh to 110 mm Hg above systolic blood pressure) in addition to standard care or standard care alone.

Main Outcomes and Measures

The change in brain infarction volume growth between baseline and 24 hours, measured by a diffusion-weighted sequence of magnetic resonance imaging scans of the brain.

Results

A total of 188 patients (mean [SD] age, 67.2 [15.7] years; 98 men [52.1%]) were included in this intention-to-treat analysis. At hospital admission, the median National Institutes of Health Stroke Scale score was 10 (interquartile range [IQR], 6-16) and the median brain infarction volume was 11.4 cm3 (IQR, 3.6-35.8 cm3); 164 patients (87.2%) received intravenous thrombolysis, and 64 patients (34.0%) underwent mechanical thrombectomy. The median increase in brain infarction growth was 0.30 cm3 (IQR, 0.11-0.48 cm3) in the intervention group and 0.37 cm3 (IQR, 0.19-0.55 cm3) in the control group (mean between-group difference on loge-transformed change, -0.07; 95% CI, -0.33 to 0.18; P = .57). An excellent outcome (defined as a score of 0-1 on the 90-day modified Rankin Scale or a score equal to the prestroke modified Rankin Scale score) was observed in 46 of 90 patients (51.1%) in the intervention group and 37 of 91 patients (40.7%) in the control group (P = .12). No significant differences in 90-day mortality were observed between the intervention and control groups (14 of 90 patients; Kaplan-Meier estimate, 15.8% vs 10 of 91 patients; Kaplan-Meier estimate, 10.4%, respectively; P = .45) or with symptomatic intracerebral hemorrhage (4 of 88 patients [4.5%] in both groups; P = .97).

Conclusions and Relevance

In this study, treatment with remote ischemic perconditioning, during or after reperfusion therapies, had no significant effect on brain infarction volume growth at 24 hours after symptom onset.

Trial Registration

ClinicalTrials.gov Identifier: NCT02189928.

Benefit of first-pass complete reperfusion in thrombectomy is mediated by limited infarct growth

BACKGROUND AND PURPOSE

The number of clot retrieval attempts required to achieve complete reperfusion by mechanical thrombectomy impacts functional outcome in acute ischaemic stroke (AIS). Complete reperfusion [expanded Treatment In Cerebral Infarction (eTICI) score = 3] at first pass (FP), is associated with the highest rates of favorable outcome compared to complete reperfusion by multiple passes. The aim of the present study was to investigate the relationship between FP complete reperfusion and infarct growth (IG).

METHODS

Anterior AIS patients with baseline and 24-h diffusion-weighted magnetic resonance imaging were included from two prospective registries. IG was measured by voxel-based segmentation of initial and 24-h diffusion-weighted imaging lesions. IG and favorable 3-month modified Rankin Scale (mRS) score (≤ 2) were compared between patients in whom complete reperfusion (eTICI 3) was achieved with a single pass (FP group) and those for whom multiple passes were required (MP group), after matching for confounding factors. Mediation analysis was performed to examine the association between FP and 3-month mRS score, with IG as mediating variable.

RESULTS

A total of 200 patients were included, of whom 118 (28.9%) had FP complete reperfusion. In case-control analysis, the FP group had lower IG than the MP group [8.7 (5.4-12.9) ml vs. 15.2 (11-22.6) ml, respectively; P = 0.03). Favorable outcome was higher in the FP population compared to a matched MP population (70.9% vs. 53.2%, respectively; P = 0.04). FP compete reperfusion (eTICI 3) was independently associated with favorable outcome in multivariable regression analysis [odds ratio 1.86, 95% confidence interval (CI) 1.01-4.39; P = 0.04]. The effect of complete reperfusion at FP on functional outcome was explained by limited IG in mediation analysis [indirect effect: -0.32 (95% CI -0.47 to -0.09)].

CONCLUSION

Complete reperfusion at FP is independently associated with significant decrease in IG compared to complete reperfusion by multiple attempts, explaining better functional outcomes.

Self- or caregiver-delivered manual remote ischemic conditioning therapy in acute ischemic stroke is feasible: the Early Remote Ischemic Conditioning in Stroke (ERICS) trial

Background: Infarct growth and recurrent stroke may be responsible for early morbidity and mortality in patients with acute ischemic stroke. Remote ischemic conditioning (RIC) may reduce infarct growth and prevent recurrent stroke; however, the exact dose remains to be investigated. We hypothesized that self- or caregiver-delivered six cycles of RIC intervention in acute ischaemic stroke for the first 12 weeks is feasible and safe compared to the four cycles RIC intervention. Methods: Adult ischemic stroke patients presenting within the first 48 h of symptom onset were screened. Patients with magnetic resonance imaging (MRI) evidence of acute infarct were randomized (1:1) to receive either four or six cycles of RIC therapy sessions two times daily in both arms for 12 weeks. All patients underwent MRI for infarct volume assessment and endothelial-dependent flow-mediated dilation (EDFMD) testing at baseline, 7 days and 12 weeks.   Results: A total of 57 patients with mean±SD age of 59.4±12.4 years and median National Institute of Stroke Scale, 4 (IQR, 3-7) were randomised at a median of 23 h 30 min (IQR, 10 h 20 min to 30 h) after symptom onset to either the four-cycle (n=27) or six-cycle group (n=30). A total of 18 (66%) patients completed ≥50% sessions in 12 weeks in the four-cycles group; 21 (69.7%) patients completed ≥50% sessions in 12 weeks in the six-cycle group (p=0.4). There was no between-group differences in infarct growth, early neurological deterioration, recurrent stroke, and EDFMD at 7 days and 90 days. Conclusion: Both four and six cycles of short-term self- or caregiver-delivered RIC therapy is safe and may be feasible in acute ischaemic stroke patients. Randomised clinical trials are needed to assess efficacy to decrease infarct growth and prevent early neurological deterioration. Registration: Clinical Trial Registry - India: CTRI/2016/11/007495; registered on 25/11/2016.

Outcome prediction for patients with anterior circulation acute ischemic stroke following endovascular treatment: A single-center study

Previous studies have identified various factors associated with the outcomes of acute ischemic stroke (AIS) but considered only 1 or 2 predictive factors. The present study aimed to use outcome-related factors derived from biochemical, imaging and clinical data to establish a logistic regression model that can predict the outcome of patients with AIS following endovascular treatment (EVT). The data of 118 patients with anterior circulation AIS (ACAIS) who underwent EVT between October 2014 and August 2018 were retrospectively analyzed. The patients were divided into 2 groups based on the modified Rankin Scale score at three months after surgery, where 0–2 points were considered to indicate a favorable outcome and 3–6 points were considered a poor outcome. Non-conditional logistic stepwise regression was used to identify independent variables that were significantly associated with patient outcome, which were subsequently used to establish a predictive statistical model, receiver operating characteristic (ROC) curve was used to show the performance of statistical model and analyze the specific association between each factor and outcome. Among the 118 patients, 47 (39.83%) exhibited a good and 71 (60.17%) exhibited a poor outcome. Multivariate analysis revealed that the predictive model was statistically significant (χ²=78.92; P<0.001), and that the predictive accuracy of the model was 83.1%, which was higher compared with that obtained using only a single factor. ROC curve analysis shows the area under curve of the statistical model was 0.823, the analysis of diagnostic threshold for prognostic factors indicated that age, diffusion-weighted imaging lesion volume, glucose on admission, National Institutes of Health Stroke Scale score on admission and hypersensitive C-reactive protein were valuable predictive factors for the outcome of EVT (P<0.05). In conclusion, a predictive model based on non-conditional logistic stepwise regression analysis was able to predict the outcome of EVT for patients with ACAIS.

Susceptibility-weighted imaging in post-treatment evaluation in the early stage in patients with acute ischemic stroke

Objective

This study aimed to investigate the association between abnormal signs on susceptibility-weighted imaging (SWI) and post-treatment outcome in the early stage in patients with acute ischemic stroke.

Methods

Thirty-seven patients with middle cerebral artery territory infarction were recruited. Baseline and 24-hour follow-up magnetic resonance imaging was performed. Pre- and 24-hour post-treatment clinical conditions were assessed with the National Institutes of Health Stroke Scale (NIHSS) score. Prominent vessel sign (PVS) on SWI and infarcted areas on diffusion-weighted imaging (DWI) were assessed using the Alberta Stroke Program Early CT (ASPECT) score system. Susceptibility vessel sign (SVS) was evaluated and recorded. The associations between image abnormalities and clinical scores were analyzed.

Results

PVS was found in 35 patients and SVS in seven patients. The extent of PVS was significantly correlated with the post-treatment DWI ASPECT score (r = 0.79), but not with the post-treatment NIHSS score or the post−pre NIHSS difference score. The presence of SVS was significantly correlated with the post-treatment NIHSS score (r = 0.41).

Conclusion

PVS might be a useful predictor of early imaging prognosis and infarct growth in patients with acute ischemic stroke. SVS is related to a poor early outcome and could be useful for assessing stroke.

Quantifying Infarct Growth and Secondary Injury Volumes: Comparing Multimodal Image Registration Measures

BACKGROUND AND PURPOSE

Lesion expansion in the week after acute stroke involves both infarct growth (IG) and anatomic distortion (AD) because of edema and hemorrhage. Enabling separate quantification would allow clinical trials targeting these distinct pathological processes. We developed an objective and automated approach to quantify these processes at 24 hours and 1 week.

METHODS

Patients with acute ischemic stroke were scanned at presentation, 24 hours, and 1 week in a magnetic resonance imaging (MRI) cohort study. IG and AD were calculated from follow-up lesion masks after linear and nonlinear registration to a presenting MRI scan. Performance of IG and AD was compared with edema quantified using cerebrospinal fluid displacement. The use of alternative reference images to define AD, including template MRI, mirrored MRI, and presenting computed tomographic scan, was explored.

RESULTS

Thirty-seven patients with nonlacunar stroke were included. AD was responsible for 20% and 36% of lesion expansion at 24 hours (n=30) and 1 week (n=28). Registration-defined IG and AD compared favorably with edema quantified using cerebrospinal fluid displacement, particularly at smaller infarct volumes. Presenting computed tomographic imaging was the preferred alternative reference image to presenting MRI for measuring AD.

CONCLUSIONS

The contributions of IG and AD to lesion expansion can be measured separately over time through the use of image registration. This approach can be used to combine imaging outcome data from computed tomography and MRI.

Body Temperature Modulates Infarction Growth following Endovascular Reperfusion

BACKGROUND AND PURPOSE

The neuronal substrate is highly sensitive to temperature elevation; however, its impact on the fate of the ischemic penumbra has not been established. We analyzed interactions between temperature and penumbral expansion among successfully reperfused patients with acute ischemic stroke, hypothesizing infarction growth and worse outcomes among patients with fever who achieve full reperfusion.

MATERIALS AND METHODS

Data from 129 successfully reperfused (modified TICI 2b/3) patients (mean age, 65 ± 15 years) presenting within 12 hours of onset were examined from a prospectively collected acute ischemic stroke registry. CT perfusion was analyzed to produce infarct core, hypoperfusion, and penumbral mismatch volumes. Final DWI infarction volumes were measured, and relative infarction growth was computed. Systemic temperatures were recorded throughout hospitalization. Correlational and logistic regression analyses assessed the associations between fever (>37.5°C) and both relative infarction growth and favorable clinical outcome (90-day mRS of ≤2), corrected for NIHSS score, reperfusion times, and age. An optimized model for outcome prediction was computed by using the Akaike Information Criterion.

RESULTS

The median presentation NIHSS score was 18 (interquartile range, 14-22). Median (interquartile range) CTP-derived volumes were: core = 9.6 mL (1.5-25.3 mL); hypoperfusion = 133 mL (84.2-204 mL); and final infarct volume = 9.6 mL (8.3-45.2 mL). Highly significant correlations were observed between temperature of >37.5°C and relative infarction growth (Kendall τ correlation coefficient = 0.24, P = .002). Odds ratios for favorable clinical outcome suggested a trend toward significance for fever in predicting a 90-day mRS of ≤2 (OR = 0.31, P = .05). The optimized predictive model for favorable outcomes included age, NIHSS score, procedure time to reperfusion, and fever. Likelihood ratios confirmed the superiority of fever inclusion (P < .05). Baseline temperature, range, and maximum temperature did not meet statistical significance.

CONCLUSIONS

These findings suggest that imaging and clinical outcomes may be affected by systemic temperature elevations, promoting infarction growth despite reperfusion.

Predictors of clinical outcome in patients with acute perforating artery infarction

BACKGROUND AND PURPOSE

We aimed to determine the predictive factors for super-acute perforating artery infarctions (PAI) involving lenticulostriate arteries infarctions (LSAI), anterior pontine arteries infarctions (APAI) and thalamic arteries infarctions (TAI). Whether intravenous thrombolysis (iv-tPA) therapy would influence the clinical outcome was also studied.

METHODS

We analyzed 84 consecutive patients within 12h of stroke symptom onset from January 2008 to June 2015. All patients had an imaging-proven acute infarction in the perforating territory of LSA (n=53), TA (n=21) and APA (n=10). Favorable clinical outcome was defined as modified Rankin Scale ≤1 at 90days. Patients were divided into groups according to clinical outcome, lesion location and thrombolysis therapy. Baseline demographic data, past medical history, National Institutes of Health Stroke Scale (NIHSS) score and infarction volume were compared between groups.

RESULTS

Eighty-four patients were recruited (median age: 61y; 67.9% male). All patients with TAI (n=21), 34/53 (64.2%) patients with LSAI and 4/10 (40%) patients with APAI achieved favorable clinical outcome (mRS≤1). Ninety-day clinical outcome was associated with age, previous stroke, baseline NIHSS, infarct location, infarct volume. Intravenous thrombolysis improved 24h NIHSS, but was not significantly associated with favorable outcome at 90days. In multivariate analysis, only previous stroke/TIA (OR 0.09, 95%CI 0.01-0.68, p=0.020) and infarct volume (OR 0.64, 95%CI 0.43-0.96, p=0.032) were independently associated with the outcome of acute PAI at 90days.

CONCLUSIONS

Previous stroke/TIA, infarct location and infarct volume were independently associated with the short-term clinical outcome of acute PAI.

Comparison between voxel-based and subtraction methods for measuring diffusion-weighted imaging lesion growth after thrombolysis

Background

Infarct growth (IG) is used as surrogate end-point in therapeutic trials. For practical reasons, infarct growth is commonly assessed using simple subtraction of acute from follow-up diffusion-weighted imaging (DWI) lesion volumes. However, the volume subtraction method will underestimate true infarct growth in case of diffusion-weighted imaging lesion reversal.

Aim

To measure the size of the difference between true infarct growth on voxel-based coregistration and infarct growth approximated with simple volume subtraction.

Methods

We retrospectively analyzed 322 consecutive stroke patients (median (IQR) age: 70 years (57–80), National Institute of Health Stroke Score at admission 14 (8–19)), who underwent a magnetic resonance imaging before (DWI1) and ≈24 h (DWI2) after IV-thrombolysis. IGvoxel-based was defined as the volume of signal changes on DWI2 that did not overlap with that on coregistered DWI1. This was compared with simply subtracting DWI1 from DWI2 lesion volume (IGsubtracted). We also compared these two metrics for the prediction of three-month unfavorable outcome (mRS ≥ 2) using c-statistics of multivariable models, adjusted for age, and National Institute of Health Stroke Score.

Results

Infarct growth volume metrics were strongly correlated (ρ = 0.94), but IGsubtracted substantially underestimated IGvoxel-based (median (IQR): 9.52 (0.23–38.9) vs. 16.98 (4.4–45.4) mL). Of the 75 patients with shrinking or stable diffusion-weighted imaging lesion using volume subtraction, IGvoxel-based was ≥5 mL in 20 (27% of the subset, 6.2% of the whole population). Moreover, IGvoxel-based better predicted unfavorable outcome than IGsubtracted (c-statistics = 0.86 (95% CI, 0.82–0.90) vs. 0.82 (0.78–0.87), P = 0.003).

Conclusion

At early post-thrombolysis time points, the simple subtraction of lesion volumes masked substantial diffusion-weighted imaging lesion growth in 6.2% of patients. Although more time-consuming, the voxel-based method may impact results of trials that use infarct growth attenuation as an end-point.