Basics of bubbles
Résumé
The density and compressibility parameters of blood cells hardly differ from those of plasma. Therefore, blood cells are poor scatterers in the clinical diagnostic frequency range. Since imaging blood flow and measuring organ perfusion are desirable for diagnostic purposes, markers should be added to the blood to differentiate between blood and other tissue types. Such markers must be acoustically active in the medical ultrasonic frequency range. In this lecture, microbubble behaviour in an ultrasound field is explored, with special attention to the influence of the bubble shell. An overview of contemporary ultrasound contrast agents is given, and the physical differences between different agents are explained.