Study of a "biological focal region" of high-intensity focused ultrasound.
The aim of this study was to explore a law of energy deposition of high-intensity focused ultrasound (HIFU) in various tissues and the expression of such a law. A focused ultrasound (US) tumor therapeutic system was used to apply a focused US beam to tissues both in vivo and in vitro. The formation of individual ellipsoid-shaped regions of coagulative necrosis has been observed. Results showed that the volume of the ellipsoid-shaped coagulative necrosis region was different from that of the acoustic focal region (AFR), both in vitro and in vivo. Acoustic intensities ranging from 7 x 10(3) W/cm(2) to 27.7 x 10(3) W/cm(2) and exposure times from 1 to 20 s gave volumes of ellipsoid-shaped coagulative necrosis of 0.2 to 2000 mm(3). Although the HIFU doses applied were identical, the volumes of individual ellipsoid-shaped coagulative necrotic regions varied with the structures of tissues, their functional status and the irradiation depths. Individual ellipsoid-shaped regions of coagulative necrosis induced by HIFU can be added to produce coagulative necrosis of an entire tumor. We define the individual ellipsoid-shaped coagulative necrosis produced by the US energy deposition of a single exposure as the "biological focal region" (BFR) of HIFU. This serves as the basic unit for HIFU ablation of tumors, and is plotted as a function of AFR, acoustic intensity, exposure time, irradiation depth, the tissue structure and its functional status.
Wang
Zhibiao
Z
Institute of Ultrasonic Engineering in Medicine of Chongqing University of Medical Sciences, Daping, Chongqing, China. wangzhibiao@netease.com
Bai
Jin
J
Li
Faqi
F
Du
Yonghong
Y
Wen
Shuang
S
Hu
Kai
K
Xu
Guihua
G
Ma
Ping
P
Yin
Niangang
N
Chen
Wenzhi
W
Wu
Feng
F
Feng
Ruo
R
D000818:Animals; D007668:Kidney / Q000473:pathology; D008099:Liver / Q000473:pathology; D009132:Muscles / Q000473:pathology; D009336:Necrosis; D009369:Neoplasms / Q000628:therapy; D013552:Swine; D013997:Time Factors; D014464:Ultrasonic Therapy / Q000379:methods*