In physics, impedance is the opposition a system presents to the flow of energy. In the context of medical ultrasound, acoustic impedance is a critical property of tissue, defined as the product of tissue density and the speed of sound within that tissue. This fundamental concept dictates how sound waves behave at interfaces between different tissues, influencing reflection and transmission.
Understanding acoustic impedance is essential for diagnostic ultrasound, as significant differences in impedance between adjacent tissues lead to strong reflections, creating clear images. For example, the high impedance mismatch between bone and soft tissue causes strong reflections, resulting in acoustic shadowing. Optimizing ultrasound imaging relies on leveraging these impedance differences to achieve superior diagnostic clarity.
