Intraluminal ultrasonic palpation: Assessment of local and cross-sectionaltissue stiffness

Many intravascular therapeutic techniques for the treatment of significant atherosclerotic lesions are mechanical in nature: examples are angioplasty, stenting and atherectomy, The selection of the most adequate treatment wou ld be advantageously aided by knowledge of the mechanical properties of the lesion and surrounding tissues. Based on the success of intravascular ultr asound (IVUS) in accurately depicting the morphology of atheromatous lesion s, ultrasonic tissue characterisation has been proposed as a tool to determ ine the composition of atheroma, We describe the addition of local complian ce information to the IVUS image in the form of a colour-coded line congrue nt with the lumen perimeter. The technique involves analysis of echo signal s obtained at two or more states of incremental intravascular pressure, Usi ng vessel phantoms and specimens, we demonstrate the utility of intravascul ar compliance imaging, The palpograms are able to identify lesions of diffe rent elasticity independently of the echogenicity contrast, because the inf ormation provided by the elastograms is generally independent of that obtai ned from the IVUS image. Thus, the palpogram can complement the characteris ation of lesion from the IVUS image. We also describe cross-sectional measu res of elasticity that are based on the elastogram, Finally, natural extens ions of intravascular palpation to other endoluminal ultrasound application s are proposed. (C) 2000 World Federation for Ultrasound in Medicine & Biol ogy.