DISPLACEMENT AND STRAIN IMAGING OF CORONARY-ARTERIES WITH INTRALUMINAL ULTRASOUND

Tissue elasticity can be estimated from displacement and strain images acquired under controlled deformation, We extend this approach for co ronary arteries, deformed and imaged by an integrated angioplasty ball oon and ultrasonic imaging probe. Because the lumen cross section of a severely occluded artery is not circular, we have also developed a te chnique to perform all motion computations in the reference frame of t he lumen's geometric center. This coordinate system is independent of the imaging catheter and consequently referencing to this frame remove s artifacts associated with probe motion within the balloon during def ormation, Displacements and strains estimated by phase-sensitive corre lation-based speckle tracking were used to distinguish arterial plaque s in simulated coronary arteries of differing elastic moduli: hard, so ft, and homogenous. We have also applied these methods to images of a homogeneous gelatin phantom collected with the integrated probe, The m aximum phantom displacement was about 40 mu m, and the maximum radial normal strain was about 4% (absolute value), The spatial dependence of these quantities shows good agreement with theoretically predicted va lues.