Quantitative evaluation of bending components in propagation of small vibrations on vessel wall

We have proposed a new method for diagnosis of early stage of arteriosclerosis by measuring small vibrations on arterial wall. In our previous study, we found that propagation velocity of the small vibrations on vessel wall strongly depends on Young's modulus in axial direction of the medium. In this paper, a new function is introduced to quantitatively evaluate frequency band, in which bending components of small vibrations propagate on the vessel wall. For the component of the bending vibration of cylindrical shells, anterior and posterior walls vibrate simultaneously with keeping their cross sectional shape. This fact indicates that resultant signals of the anterior and posterior walls have same phase. By applying these physical meanings to spectrum analysis, the new function is defined.