Research progress on the value of CT and MRI in predicting hemorrhagic transformation after acute ischemic stroke

Cerebral infarction is the second leading cause of death in the world, and has become the most serious cause of disability and death in China. Acute ischemic stroke (AIS) is the most common type of cerebral infarction, accounting for about 80% of all cerebral infarctions. Hemorrhagic transformation (HT) is one of the natural regression processes in patients with AIS, and is the most serious complication after treatments [such as intravenous thrombolysis (IVT) or endovascular thrombectomy (EVT)], which brings a heavy burden for patients and their families and even the all society. Accurate prediction and evaluation are of important clinical significance. In recent years, imaging research has focused on the value of CT and MRI in evaluating HT. The diagnostic value of CT plain scan is limited. Before AIS treatment, an early diagnostic score ≤ 7 points in the Alberta Cerebral Infarction Plan is associated with the occurrence of HT (P=0.033), and high-density middle cerebral artery sign is an independent risk factor for the occurrence of HT (OR=10.334). For AIS patients treated with thrombectomy within 2-7 days, dual energy CT scanning at 24 hours after therapy had a high efficacy for prediction of HT occurrence, with a sensitivity of 82.5% and specificity of 100%. CT angiography suggests that patients with high thrombus burden had a higher probability of developing HT (OR=1.28). The incidence of HT in AIS patients with good collateral circulation is low. CT perfusion imaging parameters, including surface permeability, cerebral blood volume, Tmax, etc., have good predictive value for predicting HT occurence. In MRI plain scan, high signal on FLAIR can predict the occurrence of HT. The volume of high signal areas on MRI diffusion-weighted imaging can predict HT, with area under the ROC curve of 0.78.Brush like sign, and micro bleeding lesions on sensitivity weighted MRI indicate the occurrence of HT. Enhanced T1 weighted imaging of MRI shows a significant correlation between brain parenchymal enhancement and HT occurrence (P