Online Journal
IF値: 0.677(2017年)→0.966(2018年)


Journal of Medical Ultrasonics

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1985 - Vol.12

Vol.12 No.06

Original Article(原著)

(0497 - 0505)


Time Serial Changes of Gray Levels on B-mode Images in Experimental Myocardial Infarction −A Study on Cardiac Ultrasonic Tissue Characterization−

島津 敬1, 松本 正幸1, 西岡 浩嗣1, 藤原 誠1, 松山 泰三1, 前田 孝男1, 浜中 康彦1, 北畠 顕1, 志村 孚城1, 三輪 博秀1, 井上 通敏1, 鎌田 武信1

Takashi SHIMAZU1, Masayuki MATSUMOTO1, Hirotsugu NISHIOKA1, Makoto FUJIWARA1, Taizo MATSUYAMA1, Takao MAEDA1, Yasuhiko HAMANAKA1, Akira KITABATAKE1, Takaki SHIMURA1, Hirohide MIWA1, Michitoshi INOUE1, Takenobu KAMADA1

1大阪大学医学部第一内科, 2金沢医科大学老人病科, 3富士通研究所

1The First Department of Medicine, Osaka University Medical School, 2The Department of Geriatrics, Kanazawa Medical College, 3Fujitsu Laboratory Ltd.

キーワード : Ultrasonic tissue characterization, Myocardial infarction, Gray level analysis, Hydroxyproline

 To determine the feasibility and limitation of gray level analysis of 2-D echocardiograms in detecting myocardial infarction, sequential changes in gray levels of B-mode images of normal and infarcted canine myocardium were studied in vitro. Myocardial infarction was produced by ligating left anterior descending coronary artery in 21 mongrel dogs. These dogs were subsequently reanesthetized and killed on postoperative days 3(n=6), 7(n=5), 14(n=6) and 28(n=4), and we excised the infarcted myocardium from per fusion area of the ligated artery. Normal myocardium was also excised from the opposite side of left ventricle. We obtained the B-mode images of the specimen in the sample bath filled with physiological saline using 3 different transducers with center frequencies of 2.25, 3.5 and 5.0 MHz. Gray levels of the myocardial images were measured using a lightmeter. Changes in histological findings and hydroxyproline content were also determined. At 3 days after ligation, gray levels of infarcted myocardium showed no significant difference compared with the normal with all ultrasounds used. One week after, however, significant increases in gray level in infarcted myocardium were shown with 3.5 and 5.0 MHz ultrasounds (3.5 MHz: 5.38±1.39 vs 8.83±1.93 cd/m2, p2, p2, p=ns). Gray levels in infarcted myocardium were significantly larger than in normal 2 and 4 weeks after coronary ligation with all three ultrasounds. Tissue contents of hydroxyproline increased significantly 2 weeks after ligation, although they showed no significant increases on third day and 7th day. In conclusion, although connective tissue is one of major determinants for echogenecity of infarcted myocardium, high frequency ultrasound such as 3.5 or 5.0 MHz of center frequency is useful for detecting early changes in infarcted myocardium, when collagen content does not still increase.