Increasingly complex vascular reconstructions and emerging endovascular therapeutic modalities have stimulated the need for improved vascular imaging. To determine the feasibility of in vivo intravascular ultrasound, a miniature probe 1 mm in diameter with a 25 MHz center frequency was used to obtain two-dimensional, 360-degree cross-sectional images. In sheep, 14 superficial femoral arteries were imaged at different sites, and a portion of each vessel was resected for immediate in vitro imaging and histologic examination. In vivo images clearly showed the intima, media, and adventitia of the vessel wall as well as the lumen-intima and mediaadventitia interfaces. There was a significant correlation in measured lumen area between resected artery ultrasound images and histologic sections.

We conclude that intravascular ultrasound can produce high-resolution dynamic images that demonstrate vessel wall architecture and allow precise calculation of lumen area.