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Background: Intracranial arterial stenosis (ICAS) is a predominant cause of ischemic stroke in Asia. Changes in the signal intensities (SIs) across ICAS lesions on time-of-flight magnetic resonance angiography (TOF-MRA) have been indicated to partially reflect the hemodynamic significance of the lesions, which we aimed to verify by correlating it with cerebral perfusion features provided by CT perfusion (CTP) imaging. Methods: Ischemic stroke or transient ischemic attack patients with unilateral symptomatic stenosis ( ≥ 50%) of intracranial internal carotid artery or middle cerebral artery (MCA) were included in this study. Change of SIs across an ICAS lesion on TOF-MRA was calculated by the distal and proximal SI ratio (SIR). Cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) within the MCA territory of ipsilateral and contralateral hemispheres were evaluated on the CTP images at the basal ganglia level. Relative CBV, CBF and MTT were defined as ratios of the values obtained from ipsilateral and contralateral hemispheres. The relationships between SIR and CTP parameters were analyzed. Results: Fifty subjects (74% male, mean age 62) were recruited. Overall, the mean SIR was 0.77 ± 0.17. SIR of ICAS was significantly, linearly and negatively correlated with ipsilateral CBV (r = -0.335, p = 0.017), ipsilateral MTT (r = -0.301, p = 0.034), and ipsilateral/contralateral MTT ratio (r = -0.443, p = 0.001). Conclusions: Diminished SIs distal to ICAS on TOF-MRA might be associated with delayed ipsilateral cerebral perfusion. Changes of the SIs across ICAS lesions on TOFMRA may be a simple marker to reflect cerebral perfusion changes in patients with symptomatic ICAS. [ABSTRACT FROM AUTHOR]

Background: Pre-treatment collateral status may be associated with the rates of successful revascularization in acute ischemic stroke patients receiving endovascular treatment (EVT). We conducted a systematic review and meta-analysis to synthesize relevant evidence currently available. Methods: Relevant full-text articles published in English since January 1, 2000, reporting associations between collateral status and successful reperfusion and/or recanalization in acute ischemic stroke patients receiving EVT in cohort or case-control studies, or randomized clinical trials, were retrieved through search of PubMed. Study selection, data extraction and study quality assessment were carried out by 2 investigators. Risk ratios (RR) were pooled for good vs. poor collaterals for the outcomes of successful reperfusion and recanalization, based on random-effects models. Subgroup analyses were conducted to explore for potential factors that might interfere with the effects of pre-treatment collateral status on reperfusion by EVT. Results: In total, 27 studies (2,366 subjects) were included in qualitative analysis, among which 24 studies (2,239 subjects) were quantitatively analyzed. Overall, good pre-treatment collaterals significantly increased the rate of both successful reperfusion (RR 1.28, 95% CI 1.17-1.40; p < 0.001) and recanalization (RR 1.23, 95% CI 1.06-1.42; p = 0.006), as compared with poor collaterals. Subgroup analyses revealed that the effects of collateral status on successful reperfusion by EVT might be different between populations with different ethnicities. Conclusions: Good pre-treatment collaterals may enhance the rates of successful reperfusion and recanalization in EVT for acute ischemic stroke. This may partly explain the favorable effects of good pre-treatment collaterals on clinical outcomes of stroke patients receiving EVT. Thus, it would be valuable to assess the collateral status prior to EVT in acute ischemic stroke. But studies are needed to further verify if the positive effects of good collaterals on revascularization by EVT are restricted to certain subgroups of patients. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]