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

The authors have proposed a new method for diagnosis of early stage of arteriosclerosis by measuring small vibrations on arterial wall. In their previous study, they found that propagation velocity of the small vibrations on vessel wall strongly depends on Young´s modulus in axial direction of the medium. Here, a new function is introduced to quantitatively evaluate the 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 the same phase. By applying these physical meanings to spectrum analysis, the new function is defined