Principles and devices.

The development of catheter-based ultrasound imaging began in the 1950s using large-diameter catheters and frequencies of between 1 and 10 MHz. In the 1970s, 360 degrees cross-sectional imaging of vessels was reported using multi-element or phase-array transducers. Since then, refinements in imaging frequency, catheter size, image quality, and computer-driven imaging platforms have transformed intravascular ultrasound (IVUS) from predominantly a research tool to an important clinical intervention.