松下 恵介, 別府 慎太郎, 石蔵 文信, 小林 春香, 照尾 優穂, 柏木 寧, 矢倉 佐知子

Keisuke MATSUSHITA, Shintaro BEPPU, Fuminobu ISHIKURA, Haruka KOBAYASHI, Yuho TERUO, Yasushi KASHIWAGI, Sachiko YAGURA

大阪大学医学部保健学科

School of Allied Health Sciences, Osaka University Faculty of Medicine, 1-7 Yamadaoka, Suita-shi, Osaka 565-0871, Japan

キーワード : Acoustic power, Contrast, Echo, Harmonic, Microbubble, Video intensity

Background Microbubbles used in contrast echo examination are destroyed by exposure to ultrasound but develop a new ultrasound wave on destruction; the so-called flash effect. Factors influencing the magnitude of the new wave have yet to be elucidated. Here we investigate the method of assessing this effect and attempt to clarify the relevant differences between contrast agents.
Methods Three contrast agents were used: Albunex, Optison (FS069), and Levovist. We used fundamental mode (3.75 MHz) and harmonic mode (2.5 to 5.0 MHz) ultrasound produced by a prototype echocardiograph (Toshiba) and measured the video intensity (VI) (256 gray scale) of each contrast agent contained in a thin rubber sack while changing acoustic power from a minimum level to high levels of +10.5 dB, +16.5 dB, and +22.5 dB.
Results VI was not changed by low acoustic power; however, it increased rapidly for a short time and then decreased rapidly when exposed to high acoustic power. The increase in VI varied with acoustic power: 30 to 60 at +10.5 dB and 70 to 115 at +22.5 dB. The increase in VI was larger in harmonic mode than in fundamental mode. The degree of decrease in VI after the flash effect correlated with the extent of increase in VI produced by the flash effect.
Conclusions The flash effect occurred with each of the contrast agents, and its magnitude varied with acoustic power and contrast agent.