Imaging of cross-sectional elasticity of arterial wall using intravascular ultrasonography (IVUS)

There have been several studies on imaging the distribution of the elasticity of arterial wall using intravascular ultrasonography (IVUS). In these studies, the elasticity is estimated only during the ventricular diastole. However, the active motion of the smooth muscle of the media is induced in the diastole, therefore, the strain measured during the diastole includes both the passive characteristic and the active characteristic of smooth muscle. In the ejection period smooth muscle has the active characteristic, however, the IVUS probe has large motion due to the pulsatile flow. We proposed a method compensating the IVUS probe position in order to measure the regional change in thickness of the arterial wall. In the basic experiments using a silicone rubber tube, in which is the pulsatile flow is generated by the artificial heart, the 2D distribution of the regional change in thickness and the elasticity is determined by the proposed method. The incremental elastic modulus is homogeneously obtained in the cross-sectional plane of the wall and its value coincides with that determined in the static pressure-strain test. Using the proposed method the change in thickness of the tube can be accurately measured, and the cross-sectional elastic image is obtained. Furthermore, in in vitro experiment using the extracted iliac artery, the 2D distribution of elasticity is obtained and compare with pathological result.