藤原 誠

Makoto FUJIWARA

大阪大学医学部第一内科

The First Department of Internal Medicine, Osaka University Medical School

キーワード : Ultrasonic tissue characterization, Myocardial infarction, Ultrasonic attenuation property, Collagen concentration

　For the development of ultrasonic cardiac tissue characterization, we investigated the serial changes of ultrasonic attenuation properties and collagen concentration in normal and infarcted myocardium in vitro. Ultrasonic examinations were carried out on 55 regions of myocardium excised from 9 dogs sacrificed 3 days, 1 week, 2 weeks and 4 weeks after coronary ligation. Attenuation coefficient (β(f)) was calculated as following equation; (β(f)) = (Pr(f)-Ps(f))/2d (Pr(f) and Ps(f) : power spectra of ultrasonic signals received through water and that through myocardial specimen (dB), d : thickness of the specimen (cm)). As a quantitative index of this attenuation properties, attenuation slope, a slope of the regression line between attenuation coefficient (β(f)) and frequency (f) over the frequency range of 2.0 to 6.5 MHz, was determined. Attenuation slopes in normal myocardium showed no significant changes until 4 weeks after coronary ligation (0.62±0.25 (dB/cm/MHz) (mean±SD)). Although attenuation slopes in infarcted myocardium showed no difference compared with those in normal myocardium on 3 days and 1 week after, they increased on 2 and 4 weeks after coronary ligation (3 days: 0.67±0.24 (p=ns), 1 week: 0.77±0.34 (p=ns), 2 weeks: 1.09±0.53 (p