The invention provides an intrusive instrument and a
viscoelasticity measuring method. Based on a
laser speckle
rheology technology, an
optical fiber image transmitting bundle is used as a guide wire main body, optical signals are transmitted, speckle images changing along with time are collected through a high-speed camera, and the
viscoelasticity of the instrument is measured by analyzing time-varying speckle signals. The method comprises the following steps: establishing a relation between speckle fluctuation and
mean square displacement of scattering particles in a viscoelastic substance, quantitatively calculating
viscoelasticity information of the detected substance, measuring plaque viscoelasticity, destroying abnormal arterial endothelial cells and inflammatory cells in plaques by using a
photodynamic therapy method, and determining the plaque viscoelasticity. The purposes of
biological tissue viscoelasticity quantitative detection, abnormal part recognition and
photodynamic therapy are achieved, viscoelasticity characteristics of plaques in blood vessels can be effectively detected, abnormal parts in the blood vessels can be recognized,
photodynamic therapy is conducted on atherosclerotic plaques and other abnormal parts through
laser, the complexity of
surgical operation is reduced, and the photodynamic therapy efficiency is improved. The development of the medical technology is promoted, and the continuous upgrading and optimization of the medical service are promoted.