Displacement and strain imaging of coronary arteries withintraluminal ultrasound

摘要

Tissue elasticity can be estimated from displacement and strainnimages acquired under controlled deformation. We extend this approachnfor coronary arteries, deformed and imaged by an integrated angioplastynballoon and ultrasonic imaging probe. Because the lumen cross section ofna severely occluded artery is not circular, we have also developed antechnique to perform all motion computations in the reference frame ofnthe lumen's geometric center. This coordinate system is independent ofnthe imaging catheter and consequently referencing to this frame removesnartifacts associated with probe motion within the balloon duringndeformation. Displacements and strains estimated by phase-sensitivencorrelation-based speckle tracking were used to distinguish arterialnplaques in simulated coronary arteries of differing elastic moduli:nhard, soft, and homogenous. We have also applied these methods to imagesnof a homogeneous gelatin phantom collected with the integrated probe.nThe maximum phantom displacement was about 40 pm, and the maximum radialnnormal strain was about 4% (absolute value). The spatial dependence ofnthese quantities shows good agreement with theoretically predictednvalues