Analysis of a System for Ultrasonic Imaging of Attenuation and Texture in Soft Tissue

Abstract

Attenuation in tissue decreases both the amplitude and the bandwidth of a reflected ultrasonic signal. Only the amplitude is restored in conventional ultrasonic equipment by amplifying the signal in a time-gain-compensator.

This paper describes a method for restoring both the amplitude and bandwidth of the signal and an implemention of this method is proposed. This consists of two main parts: a device for estimating the attenuation and a time-variable circuit. The time-variable circuit is controlled by the estimated attenuation such that its transfer function approximates the inverse of the transfer function of the attenuation within the transducer passband. Its output is then almost independent of the attenuation and contains information on the texture of the tissue. Both the texture and attenuation estimates are displayed graphically. The quality of the image of the texture can be improved by choosing a wideband transducer, since it is almost exclusively dependent of transducer bandwidth.

The performance of the method is studied using both simulated signals and signals measured in vitro.

Keywords

Attenuation imaging signal processing texture time-variable circuit tissue characterization tissue equivalent tissue model ultrasound

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