Microbubble contrast for radiological imaging: 1. Principles.

Microbubble contrast for ultrasound imaging in radiology has finally come of age, adding entirely new capabilities to real time imaging. Following a bolus injection into a peripheral vein of as little as 0.1mL of an aqueous suspension, contrast specific imaging modes show parenchymal and lesional perfusion in real time in the major organs of the abdomen and pelvis as well as breast, thyroid and prostate. These new imaging modes exploit the unique interaction between ultrasound and microbubbles, which gives rise to nonlinear echoes that are readily distinguishable from those of tissue. Furthermore, microbubbles can be deliberately disrupted by the ultrasound imaging field. The rate at which fresh bubbles then replenish the scanplane can be metered in subsequent images, offering a means to quantify both flowrate and relative vascular volume of the microvasculature in both organs and solid lesions.