Cross-sectional elastic imaging of arterial wall using intravascular ultrasonography

There have been several studies on the imaging of the distribution of the elasticity of the arterial wall using intravascular ultrasonography (IVUS). In those studies, the elasticity is estimated only during ventricular diastole. However, the viscous characteristics of the smooth muscle in the media of the arterial wall are also included in the strain measured during diastole. Alternatively, during systole, the smooth muscle has an almost purely elastic characteristic. However, the IVUS probe moves greatly due to the arrival of the pulsatile wave at the beginning of the ejection period. Therefore, in this paper, we propose a method to compensate for the movement of the IVUS probe in order to precisely measure the regional change in thickness of the arterial wall during one cardiac cycle. Basic experiments using a silicone rubber tube, in which pulsatile flow is generated by an artificial heart, determined the two-dimensional (2-D) distribution of the regional change in thickness and the elasticity. The o btained incremental elastic modulus coincides with that determined by the static pressure-strain test. Furthermore, in an in vitro experiment performed on an extracted human iliac artery, the 2-D distribution of elasticity is obtained and compared with pathological results.