STRAIN IMAGING OF CORONARY-ARTERIES WITH INTRALUMINAL ULTRASOUND - EXPERIMENTS ON AN INHOMOGENOUS PHANTOM

In coronary arteries, knowing the relative stiffness of atheroscleroti c lesions can help physicians select the most appropriate therapeutic modality. Because soft material supports larger strains than hard, mea surements of this quantity can distinguish tissue of differing stiffne ss. In a previous paper, we described techniques for computing displac ements and strains in coronary arteries using an integrated angioplast y and imaging catheter. Here, we demonstrate that hard and soft materi als in a tissue-mimicking phantom can be differentiated with this devi ce. Because tissue motion cannot be distinguished from catheter motion a priori, we perform all computations in the coordinate system center ed at the balloon's geometric center. This reference frame depends onl y on balloon shape and is independent of catheter motion. A specialize d correlation-based, phase-sensitive speckle tracking algorithm has be en developed to compute strain. Maximum phantom displacement was about 25 mu m, and the maximum radial, normal strain was about 1.5 percent. (C) 1996 Academic Press, Inc.