The evaluation of the degree of reduction in the cross-sectional area of an artery has important pathophysiologic and therapeutic implications. Currently, no technique can easily provide this information. In this in vitro study we evaluated the potential of a new imaging technique, intravascular high frequency ultrasound angioscopy, in the estimation of percentage of cross-sectional area stenosis of an artery. To do this, we compared intravascular high frequency ultrasound to previously-validated external high frequency ultrasound and to anatomic estimation of arterial stenosis. Using a prototype intraluminal imaging catheter with a 20 MHz ultrasound transducer at its tip, we imaged 20 arterial segments of various size (15 to 90 mm2 lumen area by anatomy) in the control state and after experimental stenosis. These arterial segments were also imaged by external high frequency ultrasound. Lumen areas were measured from calibrated ultrasound images in the control state and after stenosis, and percentage of cross-sectional area stenosis was calculated. These data were compared to the percentage of area stenosis derived from calibrated anatomic photographs of the arteries taken in the control state and after stenosis. Both intravascular ultrasound angioscopy and external high frequency ultrasound yielded high-resolution, two-dimensional, circumferential images of the arteries. Alterations in vessel area and shape were apparent after creation of stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)