Contrast response for medical ultrasound analysis

Several investigators have described the contrast performance of systems using the concept of averaged response to anechoic or weakly echoic regions. Their work has demonstrated the importance of average sidelobe level in contrast resolution. This paper discusses the use of a similar measure, called contrast response, which quantifies the ability of a system to accurately image the contrast of an anechoic region surrounded by a uniform scattering medium. The contrast response is defined as the ratio of the system output when the anechoic target is not present to the minimum output when it is present, evaluated over a range of target sizes. Contrast response analysis is useful for evaluating system operating parameters. Examples are presented which demonstrate the effects of pitch, number of active elements, aperture shading and elevation focus.