Mouse Coronary Angiography In VIVO Using Synchrotron Radiation And Image Enhancement Research

Coronary artery is the blood-supply artery of myocardial cells. The development ofcoronary artery research will be beneficial to the accurate diagnosis of heart or myocardialdisease. Mouse is widely used in the study of human heart disease because it is easy to buildvariant disease models. Unfortunately, there’s no imaging method can be used in mouse invivo heart research because of the low resolution of conventional imaging methods. It is hardto catch valuable images. Synchrotron radiation, which develops gradually recent years, hasthe features of high flux, monochromaticity, and near parallel geometry. Images produced bysynchrotron radiation are with high spatial resolution and thus, mouse coronary angiographyin VIVO may come to be realized. A methodology for mouse coronary angiography in vivousing synchrotron radiation, which is essential to physiological and pathological researches onheart coronary diseases, is to be established in our research. Major works of this dissertationcan be included as follows:1) We designed a simulation of angiography in order to determine the optimal imagingparameter in Shanghai Synchrotron Radiation Facility．Effects of imaging parameterson the quality of acquired images in simulation were analyzed and the optimalparameters were determined thereby. These parameters cover photonenergy(33-34keV), spatial resolution of detector(26μm), and the instantaneousinjection speed of contrast agent(12ml/m). Iopamidol was used as the contrast agentwhich was mixed with water in a ratio of3:1.2) In animal experiments, we used the method of right carotid artery intubation to inject contrast agent. The effectiveness of the optimal parameters and the repeatability of invivo coronary angiography were verified and the experimental procedures werestandardized.3) Discontinuous frame differential algorithm was designed to eliminate the interferenceof moving background, ribs for example, which is attributed to breathing. Firstly, grayscale correction by means of the coronary image sequence was made in order tocompensate the effect of interferes caused by unstable photon flux of synchrotronradiation. Then the matrix of correlation coefficient of rib area was calculated tochoose the most relative background frame to the specific frame with coronary arteryimaged. Next step, subtraction was made to eliminate the background and enhancethe vessel image. Mathematical Morphology Method was used to increase thecontrast of coronary artery area on subtracted images. It can remove the imagestructure which size is larger than the diameter of coronary artery. At last, we usedGray-level Co-occurrence Matrix（GLCM）to check the texture feature of the imagesbefore and after processing in order to prove the effectiveness of the algorithm.4) To extract the vessel area from the angiography image after image enhancement.Then breath period and the heart pseudo-rhythm were compared and analyzed inorder to compensate the effect of data defect caused by limited experiment conditions.Statistic methods were used to confirm the effectiveness of the image subtraction andenhancement algorithm we designed.