Study On The Diagnosis Of Cardiovascular Disease By Laser Imaging Technology

Nowadays, cardiovascular diseases are main diseases, which threat to human life and health, whereas methods of diagnosis for cardiovascular diseases are inadequate. Laser imaging technology such as optical coherence tomography (OCT) and photoacoustic imaging technology (PAT) have attracted high interests on investigation of biomedicine recently, because of its several outstanding characteristics, including intrinsic optical section, lower photon-bleaching and photo-damaging, high contrast, real-time, and non-invasive. In this thesis, laser imaging technology was developed to diagnose cardiovascular diseases, including myocardial ischemia and reperfusion, artery restenosis after balloon lesions, which provides a theoretical basis of the clinical application.1. Determination of myocardial ischemia and reperfusion degree based on OCT Objective The purpose of this research is to study the feasibility of evaluating myocardial ischemia and reperfusion by OCT.Methods The 126 male SD rats were randomly divided into experimental group and control group. Left anterior descending coronary artery of rats in experimental group were ligated and reperfused at different time (15 and 60 min after ligation) for(5min,30 min,60min,90 min,120min)and SD rats in control group were on sham operation at each set time the same as above. ECG was studied on each set time and OCT images were obtained from the reperfusion region located in anterior wall of left ventricular. Then blood was drawn and serum markers were tested on each set time in both experimental group and control group. And then the heart was removed for pathology study.Results The serum biochemistry values and histopathological characteristics in experimental group showed that the ischemic injury was much more mild with reperfusion time extending, and compared with the control group, there was significantly different (P<0.05). The total attenuation coefficient (μt) obtained from OCT images in the experimental group kept increasing with reperfusion time extending, which was significantly different from the control group (P<0.05),too.μt obtained from OCT images showed a high degree of relevance with serum biochemistry values and histopathological characteristics (P<0.01). Conclusion In the study, all of the evidences we have proved that OCT technique in evaluating the myocardial ischemia reperfusion is feasible.2. Determination of the extent of artery restenosis after balloon lesions based on OCTObjective The purpose of this research is to study the feasibility of evaluating the extent of artery restenosis after balloon lesions by OCT.Methods The 60 male SD rats were randomly divided into two groups:experimental group (ballon injury group) and control group (sham operation group), and each subgroup has 6 rats (before modeling and 2, 7, 14, 28-days after modeling). OCT images obtained from the artery were compared with serum biochemistry values and histopathological characteristics.Results The serum biochemistry values and histopathological characteristics in experimental group showed that the extent of artery restenosis was much more severe with the time of model making, and compared with the control group, there was significantly different (P<0.05). In the experimental group, the scattering coefficient (μs) obtained from OCT images kept ascending with the time of model making, which was significantly different from the control group (P<0.05), too. Andμs showed a high degree of relevance with the serum biochemistry values and histopathological characteristics (P<0.01).Conclusion In the study, all of the evidences which we have prove that the OCT technique in evaluating the extent of artery restenosis after balloon lesions is feasible.3. Determination of myocardial ischemia degree based on PAT Objective The purpose of this research is to design to study the feasibility of determining the degree of myocardial ischemia by PAT.Methods Left anterior descending coronary artery of SD rats were ligated at different time(5min,30 min,60min,90 min,120min)and SD rats in control group were on sham operation at each set time the same as above. ECG was studied on each set time. The serum markers were tested on each set time in both experimental group and control group. PAT images were obtained from the myocardial ischemia region located in anterior wall of left ventricular, and then the heart was removed for pathology study.Results The ST segment elevated≧0.1mV in experimental group after ligated; compared with the control group, there were significant differences (P<0.01). The serum biochemistry values and histopathological characteristics in experimental group showed that the ischemic injury was much more serious with experimental time extending, and compared with the control group, there was significantly different (P<0.05). The gray value obtained from PAT images in the experimental group kept decreasing with myocardial ischemia time extending, which was significantly different from the control group (P<0.05), too. The gray value obtained from PAT images showed that have relevance with serum biochemistry values and histopathological characteristics (P<0.05).Conclusion In the study, all of the evidences we have proved that PAT technique in evaluating the myocardial ischemia is feasible.The experimental results indicate that laser imaging technology is a potential tool to quantitatively visualize and analyze intrinsic species of cardiovascular diseases. The technique may prove useful to clinical diagnostics.