| BackgroundCerebrovascular disease (CVD) is the most common neurological disease in adult. Stroke had become the first cause of disability and death in China according to the latest epidemiological survey, and the incidence of stroke increased stepwise. Endovascular mechanical thrombectomy devices have provided the opportunity to directly investigate freshly retrieved thrombi which until recently were accessible. A systematic histological analysis of thromboemboli retrieved from the middle cerebral artery and intracranial carotid artery had shown there was a large diversity of histological pattern as well as in quantitative proportion of different components, despite the presence of common components of the fibrin-platelets, nucleated cells (neutrophil/monocyte) and red blood cells (RBC’s) in all cases. Animal model studies demonstrated a lesser effectiveness of tPA thrombolysis in thrombi with high fibrin content in contrast with erythrocyte-rich emboli. Characteristics of thrombus probably determined efficacy of recanalization therapy.Middle cerebral artery (MCA) is the most common location of intracranial artery occlusion. Susceptibility vessel sign (SVS) of the middle cerebral artery on gradient-recalled echo (GRE) T2*-weighted MRI, which represents red thrombus containing erythrocytes and some fibrin, may have a potential prognostic value related to recanalization or clinical outcome, and be well correlated with the hyperdense middle cerebral artery sign (HMCAS) on CT. The GRE sequence is sensitive to the susceptibility variation of paramagnetic deoxygenated haemoglobin, which leads to a fast decay of the local T2*MR signal due to a local inhomogeneity of the magnetic field. Previous studies indicated that a history of atrial fibrillation or cardioembolic stroke was associated with the presence of MCA SVS. Moreover, a recent radiological-pathological correlation study demonstrated that both GRE SVS and CT HMCAS represented red blood cell-dominant thrombi.Target clot burden, measured by thrombus length or volume, has previously been shown to be an important determinant of vessel recanalization in both intra-arterial fibrinolysis and intravenous recombinant tissue plasminogen activator (IV rtPA). Recently, a mechanical thrombectomy study showed irregular thrombus shape, but not thrombus length, decreased technical and clinical success of Merci thrombectomy in MCA trunk recanalization. However, pharmacological fibrinolysis requires plasminogen converted to active plasmin, infiltration and enzymatic digestion of fibrin strands by plasmin in target thrombi. The relationship between susceptibility vessel sign (SVS) morphology and recanalization after intravenous thrombolysis for acute ischemic stroke has not been well studied.ObjectiveWe aimed to investigated factors influencing the presence of SVS and evaluated the predictive value of SVS morphology in middle cerebral artery (MCA) recanalization, hemorrhagic transformation and clinical outcome after intravenous thrombolysis. MethodsWe retrospectively examined clinical and radiological data from72consecutive acute ischemic stroke patients with MCA occlusion who underwent MRI before and24hours after intravenous thrombolysis. We assessed recanalization with artery occlusion lesion (AOL) grading system, clinical outcome with modified Rankin scale and hemorrhagic transformation according to ECASS II criteria. We examined predictors of the presence of SVS and the association of MCA recanalization with SVS volume, length and shape.ResultsA total of72remaining patients were included for the final analysis. Of the included patients,22(30.6%) were women, with a median age of65years (mean66.14±13.19years). Mean time from onset to needle was229.10±67.77minutes. MeNIHSS score was12.90±5.92. Radiological hemorrhagic transformation was occured in27(37.5%) patients, was hemorrhage infarction occurred in18(25%), parenchymal hemorrhage occurred in9(12.5%) and symptomatic intracerebral hemorrhage occurred in3patients. Follow-up MRA24hours after rtPA infusion revealed recanalization in33(45.8%) patients and no recanalization in39(54.2%).History of diabetes mellitus (OR=0.157;95%CI:0.031-0.784; P=0.024) and baseline INR value (OR=0.215per0.1;95%CI:0.080-0.577; P=0.002) were identified to be independent predictors for the presence of MCA SVS with the binary logistic regression model of positive SVS analysis. When we replaced history of diabetes mellitus with serum glucose level, it also independently predicted a positive SVS (odds ratio0.741;95%CI:0.562to0.977; P=0.033). In addition, chronic atrial fibrillation, rather than first-detected, seemed to predict a positive SVS with a possible trend (odds ratio4.424;95%CI:0.913to21.439; P=0.065).The presence of MCASVS didn’t predict no recanalization (OR=2.333;95%CI:0.760-7.161, P=0.139), hemorrhagic transformation(OR=0.635;95%CI0.189-2.136; P=0.463) or poor clinical outcome (OR=2.003;95%CI:0.507-7.915; P=0.322) in the patients with MCA occlusion.In the50patients with a MCA SVS, SVS length was14.744±7.971mm (range3.98-38.31mm) and SVS volume was0.377±0.255ml (range0.02-1.22ml). Patients with M1occlusion had more irregular SVS. Length of SVS was longer for the irregular than the regular morphologies (18.134±8.787mm versus11.072±4.936mm, P=0.001), and volume was larger (0.490±0.270ml versus0.256±0.172ml, P=0.001). The recanalization rate was higher for the regular than the irregular groups (62.5%versus23.1%; P=0.009).Irregular shape of SVS was identified to be a better predictor of no recanalization (OR=6.153;95%CI:1.515to24.993; P=0.011)than SVS length, while not a predictor of hemorrahgic transformation and unfavorable outcome at three months.ConclusionWe found serum glucose and INR level might affect the presence of SVS. The presence of MCA SVS didn’t predict recanalization, hemorrhagic transformation and poor clinical outcome in the patients with MCA occlusion. Patients with an irregular SVS seemed to have less potential to recanalize occluded vessels. |
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