Research On Clinical Intravascular OCT Method And System

In this paper,aiming to solve the limitation of existing IVOCT(Intravascular Optical Coherence Tomography)system and combining the requirements from clinical field,we develop an algorithm to compensate the defocusing and contrast agent absorption effect and also develop an algorithm that can accurately reconstruct the stent to do stent fracture analyse.A polarization sensitive IVOCT system and its related polarization information extraction algorithm are researched.We also design and develop an IVOCT system for clinical application,and completed the laboratory verification,animal clinical experiments and human clinical research.The main innovative work of this paper is as follows:1.The imaging theory and system design of IVOCT are studied.The signal extraction methods of time-domain and frequency-domain OCT are theoretically analyzed.The noise of IVOCT and signal-to-noise ratio(SNR)based on certain optical structure is analyzed.Based on these analyses,the theoretical relationship between coupling ratio and sensitivity of the system is given.An IVOCT system is designed according to the clinical requirements and theory analyses.2.Research on defocusing and contrast agent absorption effect of IVOCT is carried out,and an algorithm of intensity compensation based on the actual parameters extracted from catheter and contrast agent is proposed.Based on the fact that different imaging catheters have different point spread functions,this paper proposes a method that can accurately extract the catheter point spread function.This algorithm can also improve SNR about 6.5 d B.3.Build a polarization sensitive IVOCT system based on depth multiplexing method and carry out the instrumental design.A method of extracting birefringence phase delay based on similar Mueller matrix is proposed.By constructing the relationship between the measurement matrix and the sample matrix,the birefringence phase delay can be obtained from the trace of the measured matrix.Compared with the similar Jones matrix method,this method can effectively eliminate the depolarization and diattenuation effects caused by fiber rotation and fallback motion.By the in vivo experiments of wave plate and other biological tissues,similar Mueller matrix can achieve more robust and stable birefringence phase delay imaging.4.The IVOCT system for clinical application is developed.Aiming to identify coronary stent fracture,this paper proposes an algorithm to accurately reconstruct the stent structure and the in vivo experiments verify the effectiveness of the algorithm to identify stent structure.Based on laboratory verification,the animal and human clinical research are carried out.The clinical trail is a multi-center,randomized controlled study design.The results show that the developed IVOCT system and catheter have the same safety and effectiveness with control group.They are the first IVOCT system and catheter manufactured by Chinese company approved by CFDA.