Use of ultrasound, namely in the biomedical diagnosis and industrial fields, pioneered in 1950s, is today particularly widespread. In the last decades, ultrasound imaging has benefited from advances in numerical technologies such as signal processing. On the other hand, the use of ultrasound imaging has increased the need for signal processing techniques.
This paper presents a review and the up-to-date developments in ultrasound imaging techniques, including elementary principles, signal acquisition and processing, from one dimensional to multidimensional systems. This paper also deals with typical relevant applications.
Due to its noninvasive and non ionizing nature and its flexibility, ultrasound (US) systems are a widely used modality for real time imaging. Though a high number of applications are met in the biomedical field, industry remains an area of important use. Ultrasound imaging is continuously growing in each of these fields. This is namely due to three reasons. The first one is linked to important advances in transducers (used for generation and detection of ultrasound) technology. The second is the improvement brought by advances in digital technologies, and namely advances in signal and image processing methods and technologies. The last one is the wide variety of applications in medical as well as in industrial areas. Concerning medical areas, for example, applications are as diverse as the different parts of the human body.
Utilization of Ultrasound imaging ranges from 1D to 4D applications. Obtaining high quality images for visualization or characterization purposes has been a big concern for long time. The first works were performed in 1D and concern the so-called A mode, that is the representation of ultrasound signal magnitude versus time. Alternatively, interrogating materials in one direction and displaying a single signal value over time as a scrolling display gives the so-called time motion (TM) mode. Generally speaking the 1D (US) signal processing is intended for quantitative extraction of a single parameter. This is typically the case for velocity estimation either through US Doppler spectrum estimation, US time of flight estimation or material or tissue characterization ,. Multi-dimensional signal or image, namely 2,3 or 4D processing, deals on one hand with improvement of image quality in terms of speckle processing, resolution, contrast enhancement and on the other hand with appropriate image visualization.