Study Of Relative Factors Of Acoustic Densitometry

Objective: To testify the reliability of myocardial backscatter intensity measured by commercial ultrasonography. Methods: 60 rabbits were divided randomly into 2 groups. The integrated backscatter at end of systole or at end of diastole of the rabbits was measured. Then hyper calcium resolution or hyper potassium resolution were injected into the coronary artery to one group respectively to make heart stop at diastole or at diastole. Commercial ultrasonograph and special ultrasound radio signal analysis equipment were used to measure the myocardial integrated backscatter respectively. Results: Diastolic or systolic myocardial integrated backscatter of hearts in vitro were both similar to those of heats in vivo. Diastolic myocardial integrated backscatter wassignificantly higher than systolic one either in vivo or in vitro. Intensity of radio signal also had this variation between in diastole and in systole. Conclusion: Acoustic densitometry is reliable in evaluation of myocardial physical characterization.Part II. Mould study with suspension1. Acoustic densitometry in varied concentrations of amylum suspensionObjective: To compare the sensitivity of video and ultrasonic backscatter signal analyses in determination of scatter factors concentration variation and to find the relation between scatter factors concentration and acoustic properties. Methods: Varied concentrations of amylum suspension from 0.1% to 2 % were undertook the analysis of video intensity and backscattef integration.Results: Concentration-video intensity and concentration-backscatter integration of amylum suspension had similar form; both had an ascendant slope, a plateau and a descendant slope. But the ascendant amplitude of backscatter curve (about 30dB) is higher than that of video intensity curve (about 20dB). Conclusions: Backscatter integration analysis has higher sensitivity than video intensity analysis. Increased concentration of scatter will bring about increased attenuation in the backfield.Part III. Biological study1. Study of histologies) structure of myocardium I. Relationship between microstructure of left ventricleand cyclic variation of myocardial ultrasonic backscatter integrationObjective: To explore the histological mechanism of myocardial integrated backscatter varying cyclically. Methods: 60 SD rats were divided randomly into 2 groups. Hyper calcium resolution or hyper potassium resolution were injected into the coronary artery to one group respectively to make heart stop at diastole or at diastole. Correlation between myocardial historical structure and ultrasonic backscatter integration was analyzed. Results: Number of micro vessel, mean vessel diameters, length of myocardial fiber, width of myocardial fiber and area of conjunctive tissue are all different between in diastole and in systole. Conclusion: Histology structure difference between in diastole and in systole is the foundation of cyclic variation of ultrasonic backscatter integration.II. Physiological factor study1. Influence of concentration of blood on myocardial ultrasonic backscatter integrationObjective: To explore the influence of concentration of blood on myocardial ultrasonic backscatter integration under various perfusion pressure in vitro. Methods: 40 hearts in vitro of rabbits were perfused with whole blood or substitutive plasma alternately under the pressure from 0 to 200 mmHg. Backscatter integration of myocardium was measured. Results: Myocardial backscatter integration increased together with the increase of perfusion pressure created by either whole blood or substitutive plasma.Myocardial backscatter integration was always higher while perfusing with whole blood than perfusing by substitutive plasma uAder each pressure. Conclusion: Concentration -of blood .Juts significant influence on myocardial ultrasonic backscatter integration.2. Influence of perfusing pressure on myocardial ultrasonic backscatter integrationObjective: To explore the influence of perfusing pre...