title: Study of a "biological focal region" of high-intensity focused ultrasound.
abstract: 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.
authors.affiliation: Institute of Ultrasonic Engineering in Medicine of Chongqing University of Medical Sciences, Daping, Chongqing, China. wangzhibiao@netease.com
authors.forename: Zhibiao
authors.initials: Z
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Bai
authors.forename: Faqi
authors.initials: F
authors.lastname: Li
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Du
authors.forename: Shuang
authors.initials: S
authors.lastname: Wen
authors.forename: Kai
authors.initials: K
authors.lastname: Hu
authors.forename: Guihua
authors.initials: G
authors.lastname: Xu
authors.forename: Ping
authors.initials: P
authors.lastname: Ma
authors.forename: Niangang
authors.initials: N
authors.lastname: Yin
authors.forename: Wenzhi
authors.initials: W
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Wu
authors.forename: Ruo
authors.initials: R
authors.lastname: Feng
mesh_terms: 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*