Introduction

3D imaging techniques such as CT, MRI and PET, will be familiar to the modern imaging specialist. The strength of ultrasound imaging lies in its real-time ability and, as this book has discussed to this point, this has been based on 2D imaging. The operator moves the 2D transducer around and, where necessary, builds up a 3D map in his or her own head of the 3D structures in the body. Many modern ultrasound systems now come with a 3D scanning option which is available for the operator to use. Clinical uses for these systems are becoming established, mainly in obstetrics and cardiology as discussed below. The purpose of this chapter is to describe the technology of 3D ultrasound, including examples of clinically useful applications and measurements. Further reading, on the history and technology of 3D ultrasound, may be found in review articles by Fenster et al. (2001) and Prager et al. (2009).

Terminology

The terms ‘1D’, ‘2D’, ‘3D’ and ‘4D’ are used. The ‘D’ in every case refers to ‘dimension’. ‘1D’ is one spatial dimension, in other words a line; for example a 1D transducer consists of a line of elements. ‘2D’ is two spatial dimensions, which is an area. A 2D transducer consists of a matrix of elements. ‘3D’ is three spatial dimensions, in other words a volume.