Research On Modeling And Simulation Of Intravascular Photoacoustic Images

Intravascular photoacoustic(IVPA) imaging combines the contrast of optical absorption with the spatial resolution of ultrasound for deep imaging. Plaque composition and morphology of blood vessels and other information in real time image section could be abtained?The structure of blood vessels, the types of plaques and the image reconstruction parameters are reasons why there are differences between IVPA images. In addition, the calibrating of parameters for imaging equipment such as imaging catheter can also affect the imaging results. The degree of accuracy for diagnosis, the setting and optimizing of imaging catheter and image processing algorithms are all relies on the analysis of a large number of IVPA images. However,there is a shortage of IVPA images because the technology has not been used clinically.The purpose of this dissertation is to get a large number of IVPA images by building a model for IVPA image simulation. Firstly, a model of vascular cross section with atherosclerotic plaques has been built, which described the structure and distribution of optical parameters of the cross section. Secondly, the light propagation in the biological tissues has been simulated to get optical energy distribution. Thirdly,photoacoustic signal generation by the target tissue inclusion is simulated basing on sound wave equation. Finally, the improved image reconstruction algorithm basing on exact frequency-domain reconstruction algorithm has been used to reconstruct IVPA images in the polar coordinate view, which have been converted to IVPA images in the Cartesian coordinate view subsequently. The sequential IVPA images are also simulated based on the pulsatile dynamics of coronary arteries during the cardiac cycles.In this paper, we proposed a method for modeling and simulation of 2D IVPA images, which can adjust the vascular cross section model, change the optical and acoustic parameters of the model, and simulate the acoustic field of the multi-layer vessel wall. At the same time, the IVPA image can be reconstructed by the image reconstruction algorithm, and the sequence IVPA images can be obtained.