Ultrafast Ultrasound Imaging

Abstract

Ultrasound can be considered as a disruptive technology in the medical device arena (Christensen, 2003). A disruptive technology has the potential to break the rules of existing markets. Thanks to its real time capabilities, its non ionizing properties and its cost much lower than any other medical modality ultrasound has significantly impacted clinical segments within radiology, obstetrics, vascular or cardiology and created new markets of emergency medicine and intervention. It could, in the future, change the rules for screening (where whole breast ultrasound devices are entering the market of breast imaging), diagnosis (with the standardization of elastography techniques in the prostate) and surgery (with HIFU – High Intensity Focused Ultrasound –, histotripsy devices and therapy monitoring tools). In this context, innovations in the ultrasound field always have enormous potential. In the history of ultrasound, many innovations have been developed since its establishment as a medical imaging device in the 1960s, roughly one or two per decade (Szabo, 2004). The key innovation that launched the modality in the 1960s, is the real time imaging capability through mechanical scanning. Multichannel systems with electronic control of transducer arrays were developed in the 1970s. In the 1980s, flow analysis tools came to maturity through color flow imaging and quantitative Doppler modes (Pulse Wave Doppler PWD). In the 1990's significant improvements in image quality were made possible with the introduction of real time compounding techniques and harmonic imaging. Although many of these concepts were studied in research laboratories years before the commercial dates cited above, it is systematically the maturity of a new technology that trigger the introduction of the innovations on commercially available platforms: for example, real time imaging was triggered by microprocessors development, Doppler modes were prompted by digital signal processing chips with enough dynamics to detect, at the same time, very weak blood signal and strong tissue echoes. The introduction of low cost Analog to Digital (A/D) converters has led to fully digital systems, significantly increasing the quality of the information delivered. Harmonic imaging was triggered by large bandwidth transducers, allowing reception of the signal at twice the transmit frequency. In the first decade of the 21st century, technology moved towards extensive miniaturization leading to the introduction of high performances portable devices. Portable devices have created new markets for ultrasound the emergency market for example, underlying again the disruptive potential of the modality. Today portable devices are the primary sources of