| BackgroundIschemic stroke (IS) is the most common neurological disease, and the proportion of IS has risen to about 75%. With the increasing aging degree of population in china, IS has become the first cause of disability and death in china, and the incidence of stroke is increased annually. Intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator (rt-PA) is the guideline-recommended therapy for hyperacute stroke within 4.5 hours. However, hemorrhagic transformation (HT) is the most common and serious complication after IVT in patients with acute ischemic stroke (AIS). Because it can not only aggravate brain tissue injury, but also affect the effectiveness and safety of IVT. The excessive concern from both sides of Neurologists and patients for HT after thrombolysis has greatly restricted the clinical application of thrombolytic therapy. Therefore, how to predict HT after intravenous thrombolysis in AIS patients with acute ischemic stroke effectively, and to improve the prognosis has been a hot spot in clinical research. In recent years, with the development of imaging technology, a newly developed Magnetic resonance sequence called susceptibility-weighted imaging (SWI),which originally called blood oxygen level dependent (BOLD) venographic imaging, can reflect the sequence of tissue magnetization properties, especially the paramagnetic substances (such as deoxygenated hemoglobin and containing hemosiderin) has very high sensitivity. Deoxygenated hemoglobin (DHB) content in normal tissue are different from that in ischemic tissue, which indicated that SWI venography may indirectly reflect the rate of ischemic brain tissue oxygen metabolism. Brush sign (BS) is the enlargement of deep medullary veins (DMV) beside the ipsilateral later ventricle appearing as a series of linear signal loss composition on susceptibility-weighted imaging (SWI). More recently, a study on moyamoya disease discovered that BS may reflect low perfusion in the ischemic deep brain tissue and could be used to predict the severity of the disease. By far, there is far from conclusive that if BS on SWI can indirectly reflect the brain tissue oxygen metabolism rate and can be used for predicting hemorrhagic transformation after intravenous thrombolysis. Based on this assumption, we aimed to investigate the clinical application of hypointensive of DMV on SWI to patients with acute ischemic stroke of anterior circulation following intravenous thrombolysis and its possible underlying mechanisms.ObjectiveThis study was divided into two pieces. First of all, To evaluation appearance of Brush sign in patients with acute ischemic stroke in large artery occlusion and to find out its influencing factors. Secondly, we aimed to analyze the effects of pre-treatment brush sign on SWI on clinical outcomes after intravenous thrombolysis(ⅣT)in patients with acute ischemic stroke (AIS) of anterior circulation.MethodsWe retrospectively examined clinical and radiological date from consecutive acute ischemic stroke patients, who had major cerebral artery occlusion (internal carotid artery, middle cerebral artery Ml and M2) and treated with intravenous tissue plasminogen activator from August 2009 to October 2014 in the Second Affiliated of Hospital Zhejiang University School of Medicine. Asymmetry index (AI) was defined as the difference of intensity between ischemic and normal hemisphere on the SWI phase map. According to AI, patients were divided into 3 groups. We then investigated the relationships between BS and HT and analyzed the clinical outcome.Results476 patients with acute ischemic stroke (AIS) received intravenous thrombolysis in our hospital from August 2009 to October 2010. A total of 114 patients with acute ischemic stroke (AIS) of anterior circulation were examined by multimodal magnetic resonance imaging before and after thrombolysis. Among them,29 cases were small vessel occlusion,10 cases were posterior circulation infarction,9 cases were excluded because of the poor cooperation of the patients during the examination. Finally, of the included 66 patients were put into investigation.22 (33%) were women, (mean 68±13 years). Mean time from onset to needle was (252±88 min, mean pre-treatment National Institutes of Health Stroke Scale (NIHSS) score was 13(6～17). Radiological hemorrhagic transformation was occurred in 26 (39.4%) patients, hemorrhagic transformation occurred in 18 (25%) patients, parenchymal hemorrhage occurred in 8(12.1%) patients. BS was observed more frequently in HT group than non-HT group. According to asymmetry index, patients were divided into 3 groups:AI=0 (n=9), AI=1 (n=39), AI=2 (n=18). There was significant difference in the rate of hemorrhagic transformation among the groups (P=0.026).Ordinal logistic regression analysis of AI classification showed that baseline NIHSS score (OR=1.157,95%CI:1.071～1.249, P<0.001),SBP(OR=0.983,95%CI:0.968-0.998, P=0.024)and Atrial fibrillation (OR=2.282,95%CI:1.459-7.057, P=0.004) were an independent influencing factor of AI classification. Univariate analysis of the three groups of non-HT, HI hemorrhage and PH hemorrhage showed that there was a statistical trend (P=0.055) between the three groups, and other parameters had no significant difference. The results of Univariate analysis between PH and HI group showed that the volume of DWI in the HT group was larger (P=0.028), and the AI grade was higher (P=0.026). Binary logistic regression analysis showed that BS was independently associated with HT of patients with acute ischemic stroke following ⅣT (OR=2.589,95%CI:1.080～6.210, P=0.033). Further analysis was carried out in the subgroup analysis,24 patients were found to be reperfusion after intravenous thrombolysis and 42 patients had no reperfusion. In those without reperfusion after ⅣT, patients with higher BS grade had higher HT rate (P=0.023)ConclusionBrush sign on SWI can be used for predicting hemorrhagic transformation after intravenous thrombolysis and provide useful clinical information. |
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