The American surgeon
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Ultrasound refers to sound of any frequency greater than 20 kilohertz; that is, above the frequency for which humans can normally hear. All sound, including ultrasound, travels through different tissues at different rates of speed. The point at which adjacent tissues with different speeds of sound meet is referred to as an acoustic interface. ⋯ The resolution of ultrasound images of the breast has been greatly improved by computer-enhancement capabilities and the availability of high-frequency transducers. Although the detailed imaging of modern ultrasound allows for satisfactory evaluation of most breast lesions, there are a variety of artifacts inherent to breast ultrasound of which one must be cognizant, so as to avoid misinterpretation. This article will address a number of these issues, thereby presenting an introduction to the basic physics and principles relevant to breast ultrasound.