超声辐射力脉冲技术分级量化肝纤维化的实验研究

Experimental Study on Classifying and Quantifying Hepatic Fibrosis based on Acoustic Radiation Force Impulse

肝纤维化是慢性肝病进展到肝硬化的中间阶段,肝纤维化不同分期的硬度量化具有重要的临床意义,但目前其弹性参数检测尚不准确。该文基于超声辐射力脉冲(ARFI)技术,提出一种对肝脏组织弹性系数进行量化的新方法。通过ARFI技术产生超声辐射力推动聚焦处组织产生微小纵向位移,获取激励前后的超声回波信号,采用累积相位互相关算法检测微小位移,评估其分级肝纤维化程度的可行性;再通过Voigt粘弹性模型建立特定声辐射力下弹性系数与组织受激产生应变的关系曲线,从而获得不同分期肝纤维化组织弹性系数的绝对值。对不同分期的兔子肝脏进行实验,结果表明如果采用单一辐射力获得的纵向位移进行分期结果不稳定,而应采用多种声强度和多种脉冲宽度的辐射力下的平均纵向位移。最终得到的肝纤维化不同分期的弹性系数为:F0:(11.95±1.91)k Pa,F1:(13.28±1.89)k Pa,F2:(15.40±1.98)k Pa,F3:(16.83±2.01)k Pa,F4:(18.52±2.28)k Pa。实验结果实现了区分不同肝纤维化等级的兔子肝脏,并得到不同等级相对应的弹性参数值,为临床上肝纤维化的准确检查和诊断提供了新的方法和手段。

Liver fibrosis is the intermediate stage from chronic liver disease to cirrhosis,the quantification of stiffness of different liver fibrosis stages has important significance to clinic application.To overcome the shortcomings that elasticity detection is not yet accurate to quantitatively measure the stiffness of liver fibrosis,a new method based on acoustic radiation force impulse(ARFI)for the elastic coefficient quantification of liver tissue is proposed.In this paper,ultrasound echo signals are collected before and after the elastic tissue pushed by acoustic radiation forces to implement the strain detection by the cumulative phase autocorrelation,and the results shows that the proposed method is feasible to assess the degree of liver fibrosis.The relationship between the elasticity coefficient and the strain of the stimulated tissue is established by the Voigt viscoelastic model to obtain the absolute elastic modulus of different stages of liver fibrosis.Experiments on different fibrosis stages of rabbit liver show that the longitudinal displacement obtained using single radiation force is not stable,so the average longitudinal displacement under a variety of intensity and pulse length radiation forces is used.The elastic coefficients of the different stages of liver fibrosis are:F0:(11.95±1.91)kPa,F1:(13.28±1.89)kPa,F2:(15.40±1.98)kPa,F3:(16.83±2.01)kPa,F4:(18.52±2.28)kPa.Results illustrate that the rabbit liver with different levels of liver fibrosis is distinguished and the elastic parameters are obtained.This result provides a new means for the accurate examination and diagnosis of liver fibrosis in clinic.