Quantitative estimation of diffused liver diseases using ultrasound echo signal

The medical diagnosis using the ultrasonic cross section image has made remarkable result, and the ultrasonic diagnostic equipment is widely used. However, experience and skill of the doctor are required for the diagnosis using the ultrasonic image. We have been developing quantitative diagnostic techniques of liver diseases which can be applied to the clinical field. In this paper, we present the quantitative estimation results of diffused liver diseases. In the normal liver, many scatterers are distributed randomly, and the cross-section image obtained using an ultrasonic imaging system has many granular patterns referred to as a speckle pattern. The probability density function of the echo amplitude from the normal livers agrees well with the Rayleigh distribution function. The cirrhotic liver has many fibrotic tissue structures known as nodule structures. This echographic pattern changes with the progression of a disease such as cirrhosis. Using the processing technique that can suppress the signals from the randomly distributed scatterers which correspond to the normal liver, we extracted the quantitative information of the diseased tissue from RF echo signal of liver cirrhosis and chronic hepatitis.