Biological and physical mechanisms of HIFU-induced hyperecho in ultrasound images
- 作者：Brian A. Rabkin ; Vesna Zderic ; Lawrence A. Crum ; Shahram Vaezy
- 刊名：Ultrasound in Medicine and Biology
- 出版年：2006
- 期刊代码：82_03015629
- 类别：ph
- 出版时间：November 2006
- 卷：32
- 期：11
- 页码：1721-1729
- 文件大小：1436 K
摘要
Guidance and monitoring of high intensity focused ultrasound (HIFU) therapy, using ultrasound imaging, has primarily utilized formation of a hyperechoic region at the HIFU focus. We investigated biologic and physical mechanisms of a hyperecho, as well as safety of this phenomenon, using thermal, acoustic and light microscopy observations. Single, short-duration HIFU pulses (30–60 ms) were able to produce a hyperechoic region at the HIFU focus, 2 cm deep in a rabbit thigh muscle. When hyperechoic regions appeared, inertial cavitation was detected in vivo using a custom-made passive cavitation detection system. Light micrographs showed a large number of cavities (approximately 100/mm3), 1–10 μm in diameter, in a cytoplasm of cells located at the HIFU focus. Blood congestion was observed around a focal region, indicating an injury of microvasculature. Cellular necrosis was observed at 2 d after the treatment, while healing, scar tissue formation and regeneration were observed at 7 d and 14 d. The results indicate that a possibility of adverse tissue effects has to be taken into consideration when the hyperecho formation, induced by very-short HIFU pulses, is used for pretreatment targeting. (E-mail: adasi@u.washington.edu)