基于微泡浓度归一化处理的亚谐波信号分析及其测定门静脉压力的实验研究

门静脉高压症严重威胁患者生命，消化道大出血是致死主因。测定门静脉压力可预测出血风险、评价药物降压效果。目前门静脉导管术是测定门静脉压力主要方法，但该法有创且价昂，难以重复测量来监测肝病进展和评价药效。临床上尚缺乏准确测量门脉压力的无创方法。研究表明，超声造影时微泡产生的非线性信号强度与微泡外周压力相关，且与亚谐波信号的相关性最大，可用于血压的无创检测。然而亚谐波信号强度还受局部微泡浓度影响，且局部微泡浓度难以准确测定，目前在利用亚谐波信号测定血压的研究中，局部微泡浓度对测定结果的影响仍难以避免。归一化是一种无量纲处理方法，广泛应用于数据统计和信号处理等领域。本研究拟在前期通过无限冲激响应带通滤波获取亚谐波射频信号的基础上，制作仿体和门静脉高压动物模型，对局部微泡浓度作归一化处理后分析亚谐波射频信号强度与门静脉压力的相关性，以期无创测得门静脉压力，为门脉高压症的诊治提供早期、准确的评价指标。

Portal hypertension a serious threat to cirrhotic patients which may cause lethal gastrointestinal bleeding. Portal pressure measurement can predict the risk of bleeding and evaluate anti-hypertension effect of drug. Measurements through portal vein catheterization is the reference standard for the determination of portal pressure, however it is invasive and pricy and difficult to monitor liver disease progress through repeated measurements. Accurate noninvasive measurement of portal pressure method is needed.Studies have shown that nonlinear signal from microbubble contrast-enhanced ultrasound imaging is relavant to ambient pressure, especially the subharmonic signal.But the signal would be influence by the local microbubble concentration. Few study focused on the management of local microbubble concentration in evaluation of blood pressure using sub-harmonic signal. Normalization is a dimensionless processing method, widely used in the field of statistics and signal processing. In order to accurately analyze the relationship between sub-harmonic signal and portal pressure, local microbubble concentration should be normalized because it is difficult to control.In this study, we will make phantom and animal models of portal hypertension to explore a method of portal pressure evaluation using sub-harmonic radiofrequency signal after microbubble concentration normalization ,so as to provide early diagnosis and accurate evaluation of portal hypertension.