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Objective: This study aimed to provide an alternative approach for quantifying the volume of the ischemic core (IC) if truncation of computed tomography perfusion (CTP) occurs in clinical practice., Methods: Baseline CTP and follow-up diffusion-weighted imaging (DWI) data from 88 patients with stroke were retrospectively collected. CTP source images (CTPSI) from the unenhanced phase to the peak arterial phase (CTPSI-A) or the peak venous phase (CTPSI-V) were collected to simulate the truncation of CTP in the arterial or venous phases, respectively. The volume of IC on CTPSI-A (V CTPSI-A ) or CTPSI-V (V CTPSI-V ) was defined as the volume of the brain tissue with >65% reduction in attenuation compared with that of the normal tissue. The volume of IC on the baseline CTP (V CTP ) was defined as a relative cerebral blood flow of <30% of that in the normal tissue. The volume of the posttreatment infarct on the follow-up DWI (V DWI ) image was manually delineated and calculated. One-way analysis of variance, Bland-Altman plots, and Spearman correlation analyses were used for the statistical analysis., Results: V CTPSI-A was significantly higher than V DWI ( P < 0.001); however, no significant difference was observed between V CTP and V DWI ( P = 0.073) or between V CTPSI-V and V DWI ( P > 0.999). The mean differences between V DWI and V CTPSI-V , V DWI and V CTP , and V DWI and V CTPSI-A were 1.70 mL (limits of agreement [LoA], -56.40 to 59.70), 8.30 mL (LoA, -40.70 to 57.30), and -68.10 mL (LoA, -180.90 to 44.70), respectively. Significant correlations were observed between V DWI and V CTP ( r = 0.68, P < 0.001) and between V DWI and V CTPSI-V ( r = 0.39, P < 0.001); however, no significant correlation was observed between V DWI and V CTPSI-A ( r = 0.20, P = 0.068)., Conclusions: V CTPSI-V may be a promising method for quantifying the volume of the IC if truncation of CTP occurs., Competing Interests: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To compare the prognostic value of net water uptake (NWU) and target mismatch (TM) on CT perfusion (CTP) in acute ischemic stroke (AIS) patients with late time window., Methods: One hundred and nine consecutive AIS patients with anterior-circulation large vessel occlusion presenting within 6-24 h from onset/last seen well were enrolled. Automated Alberta Stroke Program Early CT Score-based NWU (ASPECTS-NWU) was calculated from admission CT. The correlation between ASPECTS-NWU and CTP parameters was assessed. Predictors for favorable outcome (modified Rankin Scale score ≤ 2) at 90 days were assessed using logistic regression analysis. The ability of outcome prediction between ASPECTS-NWU and TM (an ischemic core < 70 mL, a mismatch ratio ≥ 1.8, and an absolute difference ≥ 15 mL) was compared using receiver operating characteristic (ROC) curve., Results: A higher level of ASPECTS-NWU was associated with a larger ischemic core (r = 0.66, p < 0.001) and a larger hypoperfusion volume (r = 0.38, p < 0.001). ASPECTS-NWU performed better than TM for outcome stratification (area under the curve [AUC], 0.738 vs 0.583, p = 0.004) and was the only independent neuroimaging marker associated with favorable outcomes compared with CTP parameters (odds ratio, 0.73; 95% confidence interval [CI] 0.62-0.87, p < 0.001). An outcome prediction model including ASPECTS-NWU and clinical variables (National Institutes of Health Stroke Scale scores and age) yielded an AUC of 0.828 (95% CI 0.744-0.893; sensitivity 65.4%; specificity 87.7%)., Conclusion: ASPECTS-NWU performed better than TM for outcome prediction in AIS patients with late time window and might be an alternative imaging biomarker to CTP for patient selection., Clinical Relevance Statement: Automated Alberta Stroke Program Early CT Score-based net water uptake outperforms target mismatch on CT perfusion for the outcome prediction in patients with acute ischemic stroke and can be an alternative imaging biomarker for patient selection in late therapeutic window., Key Points: • A higher ASPECTS-based net water uptake was associated with larger ischemic cores and hypoperfusion volumes on CT perfusion. • ASPECTS-based net water uptake outperformed target mismatch for outcome prediction in acute ischemic stroke with extended therapeutic window. • ASPECTS-based net water uptake can be an alternative biomarker to target mismatch for selecting acute ischemic stroke patients with late therapeutic window., (© 2023. The Author(s), under exclusive licence to European Society of Radiology.)

Objective: To investigate whether truncal-type occlusion based on multiphase computed tomographic angiography (mpCTA) was more effective for predicting intracranial atherosclerotic stenosis-related occlusion (ICAS-O) than occlusion type based on single-phase computed tomographic angiography (spCTA) in patients with acute ischemic stroke with large-vessel occlusion (AIS-LVO) in the middle cerebral artery (MCA)., Methods: Data were retrospectively collected from 72 patients with AIS-LVO in the MCA between January 2018 and December 2019. The occlusion types included truncal-type and branching-site occlusions. The association between ICAS-O and occlusion type based on the 2 computed tomographic angiography patterns was analyzed, and receiver operating characteristic curves were plotted for assessment. The areas under the curve were compared to determine the difference between the predictive powers of truncal-type occlusion based on mpCTA and spCTA., Results: Among the 72 patients, 16 were classified as having ICAS-O and 56 as having embolisms. In univariate analysis, truncal-type occlusion was significantly associated with ICAS-O ( P < 0.001 for mpCTA and P = 0.001 for spCTA). After multivariable analysis, truncal-type occlusion based on both mpCTA and spCTA remained independently associated with ICAS-O ( P = 0.002 for mpCTA and P = 0.029 for spCTA). The areas under the curve were 0.821 for mpCTA and 0.683 for spCTA; this difference was statistically significant ( P = 0.024)., Conclusions: In patients with AIS-LVO in the MCA, truncal-type occlusion based on mpCTA enables more accurate detection of ICAS-O than that based on spCTA., Competing Interests: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: The etiological features of stroke in young adults are different from those in older adults. We aimed to investigate the impact of high-resolution vessel wall imaging (HRVWI) on etiologic diagnosis in young adults with ischemic stroke or transient ischemic attack (TIA)., Methods: A total of 253 young adults (aged 18-45 years) who consecutively underwent HRVWI for clarifying stroke etiology were retrospectively recruited. Two experienced neurologists classified stroke etiology for each patient using Trial of Org 10,172 in Acute Stroke Treatment categories with and without the inclusion of HRVWI diagnosis. Multivariate logistic regression was performed to determine which etiologic category would be significantly impacted after including HRVWI., Results: The etiologic classification was altered in 39.1% (99/253) of patients after including HRVWI in the conventional investigations. The proportion of patients classified as having stroke of undetermined etiology (SUE) and the proportion of patients classified as having small-artery occlusion (SAO) both significantly decreased (36.4 to 13.8% and 9.1 to 2.0%), whereas the proportion of patients classified as having large artery atherosclerosis (LAA) significantly increased (28.5 to 58.1%) (all P < 0.001). The inclusion of HRVWI had a significant diagnostic impact on young adults who were primarily classified as SAO (odds ratio [OR] 14.4, 95% confidence interval [CI] [2.9, 71.8], P < 0.001) or SUE (OR 8.3, 95% CI [2.2, 31.5], P < 0.01)., Conclusions: HRVWI had a substantial impact on etiologic classification in young adults with ischemic stroke or TIA, particularly for those primarily classified as having SAO or SUE. This impact of HRVWI will be beneficial for therapeutic decision-making., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: To assess the predictors of ghost infarct core (GIC) in stroke patients achieving successful recanalization after mechanical thrombectomy (MT), based on final infarct volume (FIV) calculated from follow-up diffusion-weighted imaging (DWI)., Methods: A total of 115 consecutive stroke patients who had undergone baseline computed tomography perfusion (CTP) scan, achieved successful recanalization after MT, and finished follow-up DWI evaluation were retrospectively enrolled. Ischemic core volume was automatically generated from baseline CTP, and FIV was determined manually based on follow-up DWI. Stroke-related risk factors and demographic, clinical, imaging, and procedural data were collected and assessed. Univariate and multivariate analyses were applied to identify the predictors of GIC., Results: Of the 115 included patients (31 women and 84 men; median age, 66 years), 18 patients (15.7%) showed a GIC. The GIC group showed significantly shorter time interval from stroke onset to CTP scan and that from stroke onset to recanalization (both p < 0.001), but higher ischemic core volume (p < 0.001), hypoperfused area volume (p < 0.001), mismatch area volume (p = 0.006), and hypoperfusion ratio (p = 0.001) than the no-GIC group. In multivariate analysis, time interval from stroke onset to CTP scan (odds ratio [OR], 0.983; p = 0.005) and ischemic core volume (OR, 1.073; p < 0.001) were independently associated with the occurrence of GIC., Conclusions: In stroke patients achieving successful recanalization after MT, time interval from stroke onset to CTP and ischemic core volume are associated with the occurrence of GIC. Patients cannot be excluded from MT solely based on baseline CTP-derived ischemic core volume, especially for patients with a shorter onset time., Key Points: • Ghost infarct core (GIC) was found in 15.7% of patients with acute ischemic stroke (AIS) in our study cohort. • GIC was associated with stroke onset time, volumetric parameters derived from CTP, and collateral status indicated by HIR. • Time interval from stroke onset to CTP scan and ischemic core volume were independent predictors of GIC., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

Background: Volumetric accuracy of using computed tomography perfusion (CTP) to estimate the post-treatment infarct in stroke patients with successful recanalization after mechanical thrombectomy (MT) has been studied a lot, however the spatial accuracy and its influence factors has not been fully investigated., Methods: This retrospective study reviewed the data from consecutive anterior large vessel occlusion (LVO) patients who had baseline CTP, successful recanalization after MT, and post-treatment diffusion-weighed imaging (DWI). Ischemic core on baseline CTP was estimated using relative cerebral blood flood (CBF) of < 30%. The infarct area was outlined manually on post-treatment DWI, and registered to CTP. Spatial agreement was assessed using the Dice similarity coefficient (DSC) and average Hausdorff distance. According to the median DSC, the study population was dichotomized into high and low Dice groups. Univariable and multivariable regression analyses were used to determine the factors independently associated with the spatial agreement., Results: In 72 included patients, the median DSC was 0.26, and the median average Hausdorff distance was 1.77 mm. High Dice group showed significantly higher median ischemic core volume on baseline CTP (33.90 mL vs 3.40 mL, P < 0.001), lower proportion of moderate or severe leukoaraiosis [27.78% vs 52.78%, P = 0.031], and higher median infarct volume on follow-up DWI (51.17 mL vs 9.42 mL, P < 0.001) than low Dice group. Ischemic core volume on baseline CTP was found to be independently associated with the spatial agreement (OR, 1.092; P < 0.001)., Conclusions: CTP could help to spatially locate the post-treatment infarct in anterior LVO patients who achieving successful recanalization after MT. Ischemic core volume on baseline CTP was independently associated with the spatial agreement., (© 2023. The Author(s).)

Background: Target mismatch (ischemic core, mismatch volume and mismatch ratio) in patients with acute ischemic stroke (AIS) highly relies on the automated perfusion analysis software., Purpose: To evaluate the feasibility and accuracy of using the ABC/2 method to rapidly estimate the target mismatch on computed tomography perfusion (CTP) imaging in patients with AIS, using RAPID results as a reference., Material and Methods: In total, 243 patients with anterior circulation AIS who underwent CTP imaging were retrospectively reviewed. Target mismatch associated perfusion parameters were derived from RAPID results and calculated using the ABC/2 method. Paired t -test was used to assess the difference of volumetric parameters between the two methods. The ability of using the ABC/2 method to predict the important cutoff volumetric metrics was also evaluated., Result: There was no significant difference in the volumes of ischemic core ( P  = 0.068), ischemic area ( P  = 0.209), and mismatch volume ( P  = 0.518) between ABC/2 and RAPID. Using RAPID results as reference, the ABC/2 method showed high accuracy for predicting perfusion parameters (70 mL and 90 mL: sensitivity=98.5% and 98.5%, specificity=100% and 100%, positive predictive value [PPV]=100% and 100%, negative predictive value [NPV]=93.8% and 92.9%; 10 mL and 15mL: sensitivity=99.6% and 99.5%, specificity=55.6% and 50.0%, PPV=96.6% and 94.8%, NPV=90.9% and 92.3%; 1.2 and 1.8: sensitivity=99.6% and 94.8%, specificity=75.0% and 96.9%, PPV=98.7% and 99.5%, NPV=90.0% and 73.8%)., Conclusion: The ABC/2 method may be a feasible alternative to RAPID for estimation of target mismatch parameters on CTP in patients with AIS.

Purpose: To evaluate the feasibility of using CT perfusion (CTP) with increased temporal sampling interval to predict the target mismatch status in acute ischemic stroke (AIS) patients with anterior circular large-vessel occlusion (LVO)., Methods: CTP with a sampling interval of 1.7 s (CTP 1.7 s ) was scanned in 77 AIS patients for pre-treatment evaluation. Simulated CTP data with sampling interval of 3.4 s (CTP 3.4 s ) or 5.1 s (CTP 5.1 s ) were reconstructed, respectively. Target mismatch was defined according to the EXTEND-IA (Extending the Time for Thrombolysis in Emergency Neurological Deficits-Intra-Arterial) and DEFUSE 3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke) trial criteria, respectively. Pearson correlation analysis, Mann-Whitney U test, Bland-Altman analysis, and chi-square test were used for statistical analysis as appropriate., Results: Significant correlations were found on the volume of ischemic core, hypo-perfused area, mismatch area, and ratio between CTP 1.7 s and CTP 3.4 s or CTP 5.1 s (all p < 0.001). There was no significant difference on the volume of ischemic core, hypo-perfused area, mismatch area, and mismatch ratio between CTP 1.7 s and CTP 3.4 s or CTP 5.1 s (all p > 0.05). Compared with CTP 1.7 s , CTP 3.4 s or CTP 5.1 s showed comparable performance in predicting the target mismatch status in the AIS patients with LVO (both p > 0.05)., Conclusions: CTPs with increased temporal sampling intervals that lead to reduced radiation doses are feasible and may provide comparable performance in predicting target mismatch status in AIS patients with LVO., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: To assess the prognostic value of Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on post-treatment diffusion-weighted imaging (DWI) for acute ischemic stroke (AIS) patients after endovascular thrombectomy (EVT) and compare it with that of infarction volume., Methods: Ninety-eight consecutive AIS patients who underwent EVT and post-treatment DWI were retrospectively enrolled. ASPECTS and infarction volume were evaluated based on post-treatment DWI, respectively. Good clinical outcome was defined as modified Rankin Scale score of 0-2 at 90 days. Predictors of good clinical outcome were evaluated using univariate and multivariate logistic regression analysis. Prognostic value of post-treatment DWI ASPECTS and infarction volume were assessed and compared using receiver-operating-characteristic curves and the DeLong method., Results: Favorable outcome was achieved in 62 (63.3%) patients. A strong correlation was found between post-treatment DWI ASPECTS and infarction volume (ρ = -0.847). Due to strong correlation and potential collinearity, two multivariate logistic regression models were respectively developed which included post-treatment DWI ASPECTS or infarction volume. As a result, post-treatment DWI ASPECTS (OR, 2.401; 95%CI, 1.567-3.678; p < 0.001) and infarction volume (OR, 0.982; 95%CI, 0.846-0.998; p = 0.002) were both independent predictors of good clinical outcome. Setting post-treatment DWI ASPECTS ≥ 6 as a cut-off value, optimal performance (AUC = 0.836; sensitivity, 87.1%; specificity, 66.7%) could be obtained in predicting good clinical outcome, which was comparable with that of infarction volume (cut-off volume, ≤ 94.87 ml; AUC = 0.821; sensitivity, 90.3%; specificity, 55.6%)., Conclusions: Post-treatment DWI ASPECTS might be a potential surrogate of infarction volume and be effective in predicting the clinical outcome of AIS patients after EVT., Key Points: • Post-treatment DWI ASPECTS correlated significantly with infarction volume. • A post-treatment DWI ASPECTS ≥ 6 best predicts good outcomes for AIS patients after EVT. • Post-treatment DWI ASPECTS has the potential in substituting infarction volume in predicting the clinical outcome of AIS patients., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

Objectives: To explore the value of post-treatment fluid-attenuated inversion recovery vascular hyperintensity (FVH) in predicting clinical outcome in patients with acute ischemic stroke (AIS) after endovascular thrombectomy (EVT)., Methods: This retrospective study reviewed data from consecutive patients with large vessel occlusion of anterior circulation between July 2017 and February 2021. Together with other variables, status of post-treatment FVH was assessed for each patient. Good outcome was defined as a 3-month modified Rankin Scale score of 0-2. Chi-square test, Fisher's exact test, independent-samples t test, multivariate logistic regression analysis, and receiver operating characteristic analysis were used as appropriate., Results: Among 84 included patients, 48 (57.1%) patients showed post-treatment FVH. Post-treatment FVH significantly correlated with incomplete recanalization (p < 0.05) and low Alberta Stroke Project Early CT Changes Score on post-treatment diffusion-weighted imaging (p < 0.05). Higher incidence of hemorrhage transformation was observed in patients with post-treatment FVH than those without (27.1% vs. 16.7%); however, the difference did not reach significance (p = 0.259). Successful recanalization (odds ratio [OR], 0.024; 95% confidence interval [CI] 0.003-0.194; p < 0.05), lower National Institutes of Health Stroke Scale scores at admission (NIHSS pre ) (OR, 1.196; 95% CI, 1.017-1.406; p < 0.05), and no post-treatment FVH (OR, 74.690; 95% CI, 4.624-1206.421; p < 0.05) were found to be independent predictors of good outcomes. Combined models integrating all three independent predictors (recanalization+NIHSS pre +post-treatment FVH) significantly outperformed the combined model without post-treatment FVH (recanalization+NIHSS pre ) in predicting clinical outcome (p = 0.004)., Conclusions: Post-treatment FVH may be an effective prognostic marker associated with clinical outcome in patients with AIS after EVT., Key Points: • Post-treatment FVH correlates with incomplete recanalization and higher infarct volume. • Post-treatment FVH is independently associated with an unfavorable outcome. • Post-treatment FVH may provide prognostic information in patients with AIS after EVT., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

Objective: To investigate the value of automated Alberta Stroke Program Early CT Score (ASPECTS)-based net water uptake (NWU) to predict tissue-level reperfusion status and 90-day functional outcomes in acute ischemic stroke (AIS) patients after reperfusion therapy., Methods: One hundred and twelve patients with AIS who received reperfusion therapy were enrolled. ASPECTS-NWU was calculated from admission CT (NWU admission ) and follow-up CT (NWU FCT ), and the difference (ΔNWU) was calculated. Tissue-level reperfusion status was evaluated via follow-up arterial spin labeling imaging. The relationship between ASPECTS-NWU and tissue-level reperfusion was evaluated. Predictors of 90-day unfavorable outcomes (modified Rankin Scale score > 2) were assessed by multivariate logistic regression analysis and receiver operating characteristic (ROC) curves., Results: Poor reperfusion was observed in 40 patients (35.7%) after therapy. Those patients had significantly elevated NWU FCT (median, 14.15% vs. 8.08%, p = 0.018) and higher ΔNWU (median, 4.12% vs. -2.03%, p < 0.001), compared to patients with good reperfusion. High ΔNWU was a significant marker of poor reperfusion despite successful recanalization. National Institutes of Health Stroke Scale score at admission (odds ratio [OR], 1.11; 95% confidence interval [CI] 1.03-1.20, p = 0.007) and ΔNWU (OR, 1.07; 95% CI 1.02-1.13, p = 0.008) were independently associated with unfavorable outcomes. An outcome prediction model including both parameters yields an area under the curve of 0.762 (sensitivity 70.3%, specificity, 84.2%)., Conclusions: Elevated NWU FCT and higher ΔNWU were associated with poor tissue-level reperfusion after therapy. Higher ΔNWU was an independent predictor of poor reperfusion and unfavorable neurological outcomes despite successful recanalization., Key Points: • ASPECTS-NWU may provide pathophysiological information about tissue-level reperfusion status and offer prognostic benefits for patients with AIS after reperfusion therapy. • Elevated NWU FCT and higher ΔNWU were correlated with poor tissue-level reperfusion after therapy. • A higher ΔNWU is an independent predictor of poor reperfusion and 90-day unfavorable outcomes despite successful recanalization., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

Background: Our study aimed to compare the time consumption and success rate between CTA- and CTP- based assessment strategy, and to clarify the risk factors associated with the CTP scan failure., Methods: Clinical and radiological data of 437 consecutive AIS patients who underwent multiphase CTA or CTP for pre-treatment evaluation were retrospectively enrolled (CTA group, n = 302; CTP group, n = 135). Time consumption and success rate of CTA- and CTP- based assessment strategy were compared using Mann-Whitney U test and Chi-Squared Test. Univariate analysis and receiver operating curve analysis were used to clarify the risk factors, and their performance in predicting the CTP scan failure., Results: Time consumption of CTP scan and reconstruction was significantly longer than that of CTA [775 s vs 263.5 s, P < 0.001]. CTP scan showed significantly higher failure rate than CTA (11% vs 1%, P < 0.001). Severe motion was the most common cause of CTP failure (n = 12, 80%). Baseline National Institute of Health Stroke Scale (NIHSS) score in CTP failure group was significantly higher than that in CTP success group [17 vs 13, P = 0.007]. Baseline NIHSS score of 11 was the optimal threshold value to predict CTP failure with an area under the curve of 0.715, a sensitivity of 86.7%, and a specificity of 45.0%., Conclusions: CTP- based strategy showed longer time consumption and higher failure rate than CTA- based strategy. High baseline NIHSS score was significantly associated with CTP scan failure in AIS patients., (© 2022. The Author(s).)

Background: Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is a grading system to assess the extent and distribution of early ischemic changes., Purpose: To assess inter-rater agreement for total and regional ASPECTS on non-contrast computed tomography (NCCT) images, CT angiography source images (CTA-SI), and CT-perfusion cerebral blood volume (CTP-CBV) maps, and their association with final infarction in patients with acute ischemic stroke (AIS)., Material and Methods: A total of 96 consecutive patients with AIS who underwent pre-treatment NCCT and CTP were retrospectively enrolled. CTA-SI was reconstructed using the raw data of CTP. Total and regional ASPECTS were assessed on baseline NCCT, CTA-SI, and CTP-CBV, and on follow-up NCCT or diffusion-weighted imaging. Follow-up ASPECTS served as the reference standard for final infarction., Results: CTP-CBV demonstrated higher concordance for total ASPECTS (interclass correlation coefficient, 0.895 vs. 0.771 vs. 0.777) and regional ASPECTS in internal capsule, lentiform, caudate nuclei, M5 and M6, compared with NCCT and CTA-SI. CTP-CBV showed a trend of stronger correlation with final ASPECTS than NCCT and CTA-SI (0.717 vs. 0.711 vs. 0.565; P  > 0.05). ASPECTS in the internal capsule (ρ, 0.756 vs. 0.556; P  = 0.016) and caudate nucleus (ρ, 0.717 vs. 0.476; P  = 0.010) on CTP-CBV were more strongly correlated with follow-up ASPECTS than NCCT. CTP-CBV showed higher accuracy for predicting final infarction in the internal capsule (92.5% vs. 90.3% and 87.1%; P  > 1.000, P  = 0.125, respectively) and caudate nucleus (87.1% vs. 79.6% and 77.4%; P  = 0.453, P  = 0.039, respectively) than CTA-SI and NCCT., Conclusion: CTP-CBV ASPECTS might be more reliable for delineating early ischemic changes and predicting final infarction.

Purpose: To assess the diagnostic accuracy of using Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on CT perfusion (CTP) map to predict a volumetric target mismatch in patients with acute ischemic stroke (AIS)., Methods: Three-hundred and seven AIS patients with an onset time within 24h or unclear onset time who underwent CTP evaluation for large vessel occlusion of anterior circulation were enrolled. CTP ASPECTS was evaluated on cerebral blood flow (CBF) and time-to-maximum (Tmax) colored maps, respectively. Automated perfusion analysis software was used to calculate the volumes of ischemic core (volume CBF<30% ) and tissue at risk (volume Tmax>6s ). Target mismatch was defined as volume CBF< 30% <70ml, volume mismatch ≥15ml, and volume Tmax >6s /volume CBF< 30% ≥1.8. Spearman correlation and receiver operating characteristic curves were used for statistical analyses., Results: Strong correlations were found between CBF ASPECTS and volume CBF<30% , and between Tmax ASPECTS and volume Tmax>6s for overall population (ρ=-0.872, -0.757) and late-arriving patients (ρ=-0.900, -0.789). Mismatch ASPECTS moderately correlated with mismatch volume for overall population (ρ=0.498) and late-arriving patients (ρ=0.407). A CBF ASPECTS≥5 optimally predicted an ischemic core volume<70ml in overall population (sensitivity, 94.4%; specificity, 80.4%) and late-arriving patients (sensitivity, 89.5%; specificity, 90.5%). A CBF ASPECTS≥6 combined with a Mismatch ASPECTS≥1 optimally identified a target mismatch in overall population (sensitivity, 84.5%; specificity, 77.0%) and late-arriving patients (sensitivity, 83.7%; specificity, 90.0%)., Conclusion: CTP ASPECTS might be useful in predicting target mismatch derived from automated perfusion analysis software, and assisting in patient selection for endovascular therapy., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To evaluate whether Alberta Stroke Program Early CT Score (ASPECTS) could provide incremental value to collateral score, and their integration could be an effective surrogate of CTP in predicting target mismatch., Material and Methods: One hundred and fifty-nine stroke patients (onset time 6-16 h or with unknown onset time) with MCA and/or ICA occlusion underwent non-contrast computed tomography (NCCT) and CT perfusion (CTP) scan for initial assessment. Simulated single-phase CT angiography (sCTA, peak arterial phase) and multiphase CTA (mCTA) were reconstructed from CTP. ASPECTS was assessed on NCCT and sCTA. Collateral score was evaluated on mCTA. Target mismatch was defined as infarct core volume < 70 mL, the mismatch ratio ≥ 1.8, and the absolute mismatch volume ≥ 15 mL. Pearson correlation analysis, Mann-Whitney U test, chi-square test, and receiver operating characteristic curve analyses were performed., Results: Median CTA source image (CTA-SI) ASPECTS was significantly lower than NCCT ASPECTS (p = 0.001). NCCT ASPECTS, CTA-SI ASPECTS, and mCTA collateral score correlated significantly with infarct core volume and mismatch ratio (all p < 0.05). Mismatch group showed significantly higher NCCT ASPECTS, CTA-SI ASPECTS, and mCTA collateral score than non-mismatch group (all p < 0.001). NCCT ASPECTS and CTA-SI ASPECTS showed comparable predicting performance with mCTA collateral score (p > 0.05). Adding CTA-SI ASPECTS to mCTA collateral score improved the performance of mCTA in predicting target mismatch (area under curve, 0.905 vs. 0.804, p = 0.003)., Conclusion: ASPECTS can provide incremental information to collateral score in predicting target mismatch. If CTP scan fails, clinical decision based on ASPECTS and collateral score might be reasonable., (© 2021. Fondazione Società Italiana di Neurologia.)

Background: The prognostic significance of hyperperfusion after reperfusion therapy in patients with acute ischemic stroke (AIS) remains controversial., Purpose: To investigate the clinical factors associated with hyperperfusion, and the 90-day prognostic value of hyperperfusion after mechanical thrombectomy in AIS patients., Study Type: Retrospective., Population/subjects: Fifty-four AIS patients who underwent mechanical thrombectomy., Field Strength/sequence: Time-of-flight MR angiography, pulsed arterial spin labeling (ASL), diffusion-weighted imaging (DWI), and susceptibility-weighted imaging were performed at 3.0T within 1 week after thrombectomy., Assessment: Clinical factors including demographics, risk factors, stroke and treatment characteristics were collected and assessed. Hyperperfusion on ASL was defined as a focal increased cerebral blood flow on the affected side ≥130% of its mirror counterpart. Good clinical outcome at 90 days was defined as modified Rankin Scale score of 0-2., Statistical Tests: The interrater agreement was assessed using Cohen's kappa or the intraclass correlation coefficient. The relationship between hyperperfusion and clinical factors were analyzed by appropriate univariate statistics. Predictors of 90-day functional outcome were assessed by univariate analyses followed by multivariate logistic regression analysis and receiver-operating-characteristic curves., Results: Thirty-six (66.7%) patients developed hyperperfusion on ASL after thrombectomy. Hyperperfusion was significantly correlated with successful recanalization (P < 0.05) and improvement of National Institutes of Health Stroke Scale scores at 24 hours (NIHSS 24h ) (P < 0.05). A higher incidence of hemorrhage transformation was observed in patients with hyperperfusion than those without (63.9% vs. 50.0%), but no significant difference was found (P = 0.327). NIHSS 24h (odds ratio [OR], 0.75, [95% confidence interval [CI] 0.62-0.91], P < 0.05), lesion volume on diffusion-weighted imaging (OR, 0.97, [95% CI 0.95-1.00], P < 0.05), and hyperperfusion on ASL (OR, 9.8, [95% CI 1.7-55.3], P < 0.05) were independent variables for predicting good functional outcomes., Data Conclusion: Hyperperfusion on ASL correlated with successful recanalization and may be an independent prognostic marker for good neurological outcomes at 90 days in AIS patients after mechanical thrombectomy., Level of Evidence: 4 TECHNICAL EFFICACY STAGE: 2., (© 2020 International Society for Magnetic Resonance in Medicine.)

Objectives: To compare collateral status on single-phase CT angiography (sCTA) and multiphase CT angiography (mCTA) and their ability to predict a target mismatch on CT perfusion (CTP) and clinical outcome in patients with acute ischemic stroke (AIS)., Methods: Seventy-three AIS patients with stroke onset between 5 and 15 h or with unclear onset time and occlusions in the M1/M2 segment of the middle cerebral artery and/or intracranial internal carotid artery underwent head non-contrast CT and CTP. Simulated sCTA and mCTA were reconstructed from CTP data and were compared for collaterals assessment. The ability to predict target mismatch on CTP (an ischemic core < 70 ml, a mismatch ratio ≥ 1.8, and an absolute difference ≥ 15 ml) and 90-day modified Rankin Scale (mRS) score of 0-2 was compared between sCTA and mCTA by using receiver operating curve analysis., Results: sCTA underestimated the collateral status when compared with mCTA (p < 0.01). The ability of mCTA to predict target mismatch (AUC = 0.902, 95% confidence interval [CI] 0.809, 0.959) and clinical outcome (AUC = 0.771; 95% CI, 0.655, 0.864) was better than that of sCTA (p < 0.05 overall). A mCTA collateral score of > 3 best identified the target mismatch (sensitivity, 78.4%; specificity, 90.9%) and predicted 90-day mRS score of 0-2 (sensitivity, 84.8%; specificity, 69.4%)., Conclusions: The collaterals were better estimated by mCTA compared with sCTA. A mCTA collateral score of > 3 optimized the prediction of a target mismatch on CTP and a good clinical outcome in patients with AIS., Key Points: • Collateral circulation is a key determinant of ischemic core and penumbra. Better collaterals are associated with smaller ischemic core volumes and larger mismatch ratios on CT perfusion. • The collaterals can be better estimated by multiphase CTA compared with single-phase CTA. • A collateral score of > 3 on multiphase CTA best identifies patients with target mismatch on CT perfusion and predicts 90-day mRS score of 0-2.

Our objective was to assess the impact of hs-cTnT elevation on functional outcome and mortality in AIS patients with large vessel occlusion (LVO) in the anterior circulation 3 months after ET and explore factors affecting hs-cTnT elevation. A total of 143 consecutive AIS patients with large vessel occlusion (LVO) in the anterior circulation following ET in a single stroke center were enrolled between January 2015 and November 2017. Hs-cTnT was quantitated on admission. Demographic characteristics, clinical data, functional outcome and all-cause mortality were compared between patients with elevated hs-cTnT levels (>14 ng/L) and those with normal hs-cTnT levels (≤14 ng/L). 58/143(40.6%) patients showed elevated hs-cTnT levels before ET. Factors independently associated with hs-cTnT elevation were admission NIHSS score (OR = 1.08, 95% CI 1.01-1.16, p = 0.032), coronary heart disease (OR = 4.89, 95% CI 1.82-13.11, p = 0.002) and congestive heart failure (OR = 4.10, 95% CI 1.07-15.68, p = 0.039). In the univariate analysis, patients with elevated hs-cTnT levels were at significantly higher risk of 3-month poor outcome (p = 0.029) and mortality (p < 0.001) than those with normal hs-cTnT levels. After multivariable analysis, hs-cTnT elevation remained an independent predictor of 3-month mortality (OR = 4.49, 95% CI 1.68-11.98, p = 0.003). In this cohort of AIS patients with LVO in the anterior circulation undergoing ET, hs-cTnT elevation is an independent predictor of 3-month mortality. Admission NIHSS score, coronary heart disease and congestive heart failure are independently associated with elevated hs-cTnT levels., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Elevated plasma homocysteine (Hcy) is an independent risk factor for ischemic stroke. This study aimed to evaluate the association between Hcy levels and intracranial plaque characteristics and to investigate their clinical relevance in ischemic stroke., Methods: Ninety-four patients with intracranial atherosclerosis (ICAS) were enrolled. Plasma Hcy levels were measured. Intracranial plaque characteristics including plaque enhancement, stenosis ratio, T2 and T1 hyperintense components were assessed on high-resolution magnetic resonance imaging. Logistic regression model was constructed to analyze the association between high Hcy levels and plaque characteristics, and their synergistic effects to predict the likelihood for ischemic stroke, while adjusting for demographics and traditional atherosclerotic risk factors., Results: Elevated Hcy level was associated with strong plaque enhancement independently of age, sex, serum creatinine levels and other atherosclerotic risk factors ((P < 0.001, OR 6.00, 95% confidence interval [CI] 2.28-15.74). Both strong plaque enhancement (P = 0.026, OR 5.63, 95% CI 1.23-25.81) and high Hcy level (P = 0.018, OR 6.20, 95% CI 1.36-28.26) were correlated with acute ischemic stroke. The combination of them strengthened the ability to stratify the likelihood for ischemic stroke, with an improved area under the receiver operating characteristic curve (AUC) of 0.871, significantly higher than that of strong plaque enhancement (0.755) and high Hcy level (0.715) alone (P < 0.05 for both)., Conclusions: High Hcy level appears to have association with intracranial strong plaque enhancement. The combined assessment of plasma Hcy levels and plaque enhancement may improve ischemic stroke risk stratification.

Objectives: The significance of atherosclerotic plaques in the parental artery with low-grade stenosis remains undetermined. We used three-dimensional high-resolution magnetic resonance imaging (3D HR-MRI) to investigate plaque distribution and characteristics of low-grade middle cerebral artery (MCA) stenosis and its clinical relevance with stroke events., Methods: We retrospectively studied 22 symptomatic patients and 24 asymptomatic patients with low-grade MCA stenosis (<50%). By 3D HR-MRI, each identified plaque was classified as either culprit (plaque on the ipsilateral side of a stroke) or nonculprit (plaques in asymptomatic patients or not within the vascular territory of a stroke). Plaque enhancement grades and distribution were assessed and compared between the groups. The association between plaque enhancement and distribution and ischemic stroke was evaluated., Results: We identified 22 culprit plaques and 31 nonculprit plaques. More culprit plaques showed contrast enhancement compared to the nonculprit plaques (95.5% versus 29.0%, P <.001). Culprit plaques were more frequently superiorly distributed than the nonculprit plaques (46.9% versus 17.5%, P <.01). Contrast enhancement (odds ratio [OR] 17.0, 95% confidence interval [CI] 3.7-77.4) and superior distribution (OR 4.2, 95% CI 1.4-12.1) of a plaque were associated with a recent ischemic stroke, of which single subcortical infarctions accounted for the largest percentage (50%)., Conclusions: Contrast enhancement and superior distribution may serve as indicators of culprit plaques in low-grade MCA stenosis, and they were significantly related to a recent ischemic stroke., (Copyright © 2018 National Stroke Association. Published by Elsevier Inc. All rights reserved.)

Background: Intracranial plaque characteristics are associated with stroke events. Differences in plaque features may explain the disconnect between stenosis severity and the presence of ischemic stroke., Purpose: To investigate the relationship between plaque characteristics and downstream perfusion changes, and their contribution to the occurrence of cerebral infarction beyond luminal stenosis., Study Type: Case control., Subjects: Forty-six patients with symptomatic middle cerebral artery (MCA) stenosis (with acute cerebral infarction, n = 30; without acute cerebral infarction, n = 16)., Field Strength/sequence: 3.0T with 3D turbo spin echo sequence (3D-SPACE)., Assessment: Luminal stenosis grade, plaque features including lesion T 2 and T 1 hyperintense components, plaque enhancement grade, and plaque distribution were assessed. Brain perfusion was evaluated on mean transient time maps based on the Alberta Stroke Program Early CT score (MTT-ASPECTS)., Statistical Tests: Plaque features, grade of luminal stenosis, and MTT-ASPECTS were compared between two groups. The association between plaque features and MTT-ASPECTS were assessed using Spearman's correlation analysis. Multivariate logistic regression and receiver operating characteristic (ROC) curves were constructed to assess the effect of significant variables alone and their combination in determining the occurrence of cerebral infarction., Results: Stronger enhanced plaques were associated with downstream lower MTT-ASPECTS (P = 0.010). Plaque enhancement grade (P = 0.039, odds ratio [OR] 5.9, 95% confidence interval [CI] 1.1-32) and MTT-ASPECTS (P = 0.003, OR 2.6, 95% CI 1.4-4.7) were associated with a recent cerebral infarction, whereas luminal stenosis grade was not (P = 0.128). The combination of MTT-ASPECTS and plaque enhancement grade provided incremental information beyond luminal stenosis grade alone. The area under the receiver operating characteristic curve (AUC) improved from 0.535 to 0.921 (P < 0.05)., Data Concusion: Strongly enhanced plaques are associated with a higher likelihood of downstream perfusion impairment. Plaque enhancement and perfusion evaluation may play a complementary role to luminal stenosis in determining the occurrence of acute cerebral infarction., Level of Evidence: 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017., (© 2017 International Society for Magnetic Resonance in Medicine.)

Objective: To determine the relationship between intravoxel incoherent motion (IVIM) imaging derived quantitative metrics and serum soluble CD40 ligand (sCD40L) level in an embolic canine stroke model., Materials and Methods: A middle cerebral artery occlusion model was established in 24 beagle dogs. Experimental dogs were divided into low- and high-sCD40L group according to serum sCD40L level at 4.5 hours after establishing the model. IVIM imaging was scanned at 4.5 hours after model establishment using 10 b values ranging from 0 to 900 s/mm 2 . Quantitative metrics diffusion coefficient (D), pseudodiffusion coefficient (D * ), and perfusion fraction (f) of ischemic lesions were calculated. Quantitative metrics of ischemic lesions were normalized by contralateral hemisphere using the following formula: normalized D = D stroke / D contralateral . Differences in IVIM metrics between the low- and high-sCD40L groups were compared using t test. Pearson's correlation analyses were performed to determine the relationship between IVIM metrics and serum sCD40L level., Results: The high-sCD40L group showed significantly lower f and normalized f values than the low-sCD40L group (f, p < 0.001; normalized f, p < 0.001). There was no significant difference in D * , normalized D * , D, or normalized D value between the two groups (All p > 0.05). Both f and normalized f values were negatively correlated with serum sCD40L level (f, r = -0.789, p < 0.001; normalized f, r = -0.823, p < 0.001). However, serum sCD40L level had no significant correlation with D * , normalized D * , D, or normalized D (All p > 0.05)., Conclusion: The f value derived from IVIM imaging was negatively correlated with serum sCD40L level. f value might serve as a potential imaging biomarker to assess the formation of microvascular thrombosis in hyperacute period of ischemic stroke.

Background: To assess the influence of the hyperintense acute reperfusion marker (HARM) on the relative signal intensity (rSI) and apparent diffusion coefficient (ADC) of hyper-acute ischemic lesions in a canine stroke model., Methods: Middle cerebral artery occlusion models were established using autologous clot embolization. Diffusion-weighted (DW) and fluid-attenuated inversion recovery (FLAIR) imaging was performed at 1, 2, 3, 4.5 and 6 h after embolization. HARM was defined as the delayed enhancement of cerebrospinal fluid on the subsequent FLAIR images after contrast media used., Results: Twenty-four stroke models were successfully established and divided into the HARM (n = 16) and No-HARM group (n = 8). No significant differences were found in the rSI on DWI (b0 and b1000 map) and relative ADC between the two groups at each time point after embolization (all P > 0.05). There were no significant differences in the rSI on FLAIR at 1 and 2 h after embolization between the two groups (P > 0.05), while the HARM group showed significantly higher rSI on FLAIR than the No-HARM group at 3, 4.5 and 6 h after embolization (P = 0.044, 0.036 and 0.001, respectively)., Conclusions: HARM should be noted during the quantitative analysis of FLAIR images in future clinical practice.

In acute stroke magnetic resonance imaging, many attempts have been made to identify the onset time of ischemic events using the simply quantitative judgment of relative signal intensity (rSI) from various MR images. However, no uniform opinion has been achieved broadly till now. The controversy might derive from the potential patients' selection bias of clinical retrospective study, the discrepant MR parameters, and the various sample sizes among different studies. Thus, we evaluated the temporal change of the relative DWI signal intensity (rDWI), relative ADC value (rADC), relative FLAIR signal intensity (rFLAIR), and relative T2 signal intensity (rT2), and further compare their diagnostic value in identifying the hyperacute lesions based on our embolic canine model with clear onset time. Twenty ischemic models were successfully established. All rSI values were linearly correlated to time with significance until 24 h after model establishment (P < 0.05). Paired comparison of ROC curves showed that significant difference was found between rADC and other three rSIs (P < 0.0001). However, no significant difference was found among rDWI, rT2 and rFLAIR. Our results indicated that rDWI, rFLAIR and rT2 may be helpful to predict the onset time of ischemic events with the similar diagnostic value. However, the rADC does not have comparable predictive value in our embolic canine model.

Stroke is one of the leading causes of death worldwide and the main reason for long-term disability. An appropriate animal model of stroke is urgently required for understanding the exact pathophysiological mechanism of stroke and testing any new therapeutic regimen. Our work aimed to establish a canine stroke model occluding the middle cerebral artery (MCA) and blocking the ipsilateral internal carotid artery (ICA), and to assess the infarct lesions by magnetic resonance imaging. The stroke model was generated by injecting two autologous clots into each MCA, followed by 2-h ipsilateral ICA blockade (ilICAB) using a catheter in 15 healthy adult beagles. Outcome measurements included 24-h and 7-day postocclusion T2-weighted imaging (T2WI)-based infarct volume calculation. In addition, pial collateral score, canine neurobehavioral score and histopathologic results were documented. Out of 15 dogs, 12 with successful MCA occlusion (MCAO) and ilICAB survived 7 days without complications or casualties and MCA were reperfused at 7 days after occlusion. High signal intensity in the basal ganglia and cerebral cortex on T2WI was initially observed in each dog at 6 h after the procedure. The mean percentage hemispherical infarct volume corrected for edema in all dogs on T2WI at 24 h after occlusion was 12.99±1.57%, and the degree of variability was 12.08%. The infarct volumes at 24 h after occlusion correlated with pial collateral scores and canine neurobehavioral scores well. This canine stroke model with combined MCAO and ilICAB reported here were proven to be highly feasible and reproducible.

Background: This study aimed to evaluate the feasibility of intraarterial (IA) delivery and in vivo MR imaging of superparamagnetic iron oxide (SPIO)-labeled mesenchymal stem cells (MSCs) in a canine stroke model., Methodology: MSCs harvested from beagles' bone marrow were labeled with home-synthesized SPIO. Adult beagle dogs (n = 12) were subjected to left proximal middle cerebral artery (MCA) occlusion by autologous thrombus, followed by two-hour left internal carotid artery (ICA) occlusion with 5 French vertebral catheter. One week later, dogs were classified as three groups before transplantation: group A: complete MCA recanalization, group B: incomplete MCA recanalization, group C: no MCA recanalization. 3×10(6) labeled-MSCs were delivered through left ICA. Series in vivo MRI images were obtained before cell grafting, one and 24 hours after transplantation and weekly thereafter until four weeks. MRI findings were compared with histological studies at the time point of 24 hours and four weeks., Principal Findings: Home-synthesized SPIO was useful to label MSCs without cell viability compromise. MSCs scattered widely in the left cerebral hemisphere in group A, while fewer grafted cells were observed in group B and no cell was detected in group C at one hour after transplantation. A larger infarction on the day of cell transplantation was associated with more grafted cells in the brain. Grafted MSCs could be tracked effectively by MRI within four weeks and were found in peri-infarction area by Prussian blue staining., Conclusion: It is feasible of IA MSCs transplantation in a canine stroke model. Both the ipsilateral MCA condition and infarction volume before transplantation may affect the amount of grafted cells in target brain. In vivo MR imaging is useful for tracking IA delivered MSCs after SPIO labeling.

Purpose: To evaluate the feasibility of intravoxel incoherent motion (IVIM) for the measurement of diffusion and perfusion parameters in hyperacute strokes.Materials and Methods: An embolic ischemic model was established with an autologous thrombus in 20 beagles. IVIM imaging was performed on a 3.0 Tesla platform at 4.5 h and 6 h after embolization. Ten b values from 0 to 900 s/mm2 were fitted with a bi-exponential model to extract perfusion fraction f, diffusion coefficient D, and pseudo-diffusion coefficient D*. Additionally, the apparent diffusion coefficient (ADC) was calculated using the mono-exponential model with all the b values. Statistical analysis was performed using the pairwise Student's t test and Pearson's correlation test.Results: A significant decrease in f and D was observed in the ischemic area when compared with those in the contralateral side at 4.5 h and 6 h after embolization (P < 0.01 for all). No significant difference was observed in D* between the two sides at either time point (P = 0.086 and 0.336, respectively). In the stroke area, f at 6 h was significantly lower than that at 4.5 h (P = 0.016). A significantly positive correlation was detected between ADC and D in both stroke and contralateral sides at 4.5 h and 6 h (P < 0.001 for both). Significant correlation between ADC and f was only observed in the contralateral side at 4.5 h and 6 h (P = 0.019 and 0.021, respectively).Conclusion: IVIM imaging could simultaneously evaluate the diffusion and microvascular perfusion characteristics in hyperacute strokes.Level Of Evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:550-556. [ABSTRACT FROM AUTHOR]

In recent years, studies have shown that the secretome of bone marrow mesenchymal stromal cells (BMSCs) contains many growth factors, cytokines, and antioxidants, which may provide novel approaches to treat ischemic diseases. Furthermore, the secretome may be modulated by hypoxic preconditioning. We hypothesized that conditioned medium (CM) derived from BMSCs plays a crucial role in reducing tissue damage and improving neurological recovery after ischemic stroke and that hypoxic preconditioning of BMSCs robustly improves these activities. Rats were subjected to ischemic stroke by middle cerebral artery occlusion and then intravenously administered hypoxic CM, normoxic CM, or Dulbecco modified Eagle medium (DMEM, control). Cytokine antibody arrays and label‐free quantitative proteomics analysis were used to compare the differences between hypoxic CM and normoxic CM. Injection of normoxic CM significantly reduced the infarct area and improved neurological recovery after stroke compared with administering DMEM. These outcomes may be associated with the attenuation of apoptosis and promotion of angiogenesis. Hypoxic preconditioning significantly enhanced these therapeutic effects. Fourteen proteins were significantly increased in hypoxic CM compared with normoxic CM as measured by cytokine arrays. The label‐free quantitative proteomics analysis revealed 163 proteins that were differentially expressed between the two groups, including 107 upregulated proteins and 56 downregulated proteins. Collectively, our results demonstrate that hypoxic CM protected brain tissue from ischemic injury and promoted functional recovery after stroke in rats and that hypoxic CM may be the basis of a potential therapy for stroke patients. Conditioned medium constitutes a therapeutic effect on stroke. Paracrine actions of bone marrow mesenchymal stromal cell are enhanced by hypoxic preconditioning. Apoptosis and neovascularization are involved in this beneficial effect. [ABSTRACT FROM AUTHOR]

Abstract: It is estimated that lacunar infarcts account for 25% of all ischemic strokes, but its exact etiology is still on debating. The existing controversies include whether the embolisms can indeed cause lacunar stroke in humans or animal models. We hypothesized that lacunar infarction can be induced by the proximal middle cerebral artery (MCA) segmental occlusion involving the orifices of lenticulostriate arteries in animal models, which have abundant distal cerebral collateral anastomosis. Our work here establishes a proximal MCA occlusion model using thrombi (autologous blood clots about 1.7mm in diameter and 5mm in length) in 8 beagle dogs, evaluates the progression of ischemic lesions at 30min interval within 6h after embolization using the diffusion weighted imaging (DWI), and discusses the potential mechanisms of lacunar infarction. Our results indicate that the left proximal MCAs can be successfully occluded in all dogs using interventional single-thrombus method. The small solitary or multiple ischemic lesions shown in DWI were observed in the deep brain area, with the mean detecting time of 1.21±0.45h using DWI and diameter of 6.62±0.60mm in 6h-DWI after procedure. In conclusion, our method established an ischemic model which can recapitulate the radiologic and histologic changes in lacunar infarcts, suggesting that emboli can cause lacunar infarcts in animal model. [Copyright &y& Elsevier]