A New Method for the Generation and Use of Focused Ultrasound in Experimental Biology

Abstract

1. An efficient generator of focused ultrasound has been designed, built, and successfully operated. 2. The generator has been used to produce focal heating in the centers of paraffin blocks, and in a similar manner, focal areas of destruction were obtained deep in fresh liver tissue with minimal effects at the surface and no effects on the intervening tissue. 3. In animals, focused ultrasound of high intensity produced local cerebral changes as inferred from behavior disabilities and as demonstrated at autopsy. This local brain effect was achieved through intervening scalp, skull, and meninges. The resulting behavior disabilities disappeared in from 2 to 16 hours. 4. To date, it has not been possible to produce such brain changes without incidental injury to the skin and subcutaneous tissue lying at the base of the cone of radiation. 5. Improvements in generation and application of the focused supersonic beam are suggested whereby it should be possible to increase still further the focal effects in the brain, with a corresponding decrease or elimination of complicating surface injury.

Successful term pregnancy following MR-guided focused ultrasound treatment of uterine leiomyoma

“…3 Focused ultrasound (FU), a non-invasive form of thermal tissue ablation, was first described in 1942. 4 Only in the last several years has the technique become sufficiently refined to permit delivery of precise and safe beam dosimetry. MRgFU for uterine leiomyomata was initially described in 2003, with preliminary series results reported by Stewart and co-workers in late 2004.…”

Local frequency dependence in transcranial ultrasound transmission

“…While several of these applications have been suggested in conjunction with craniotomies, the exploration of transcranial ultrasound transmission has opened up the possibility of non-invasive procedures. The discovery in the early 1940s that high-intensity transcranial ultrasound generated an excessive amount of heating at the skull-tissue interface (Lynn et al 1942) became a challenge for ultrasound brain therapy research and led to the assumption that craniotomies were necessary for therapeutic ultrasound procedure in the brain.…”

The safety and feasibility of extracorporeal high-intensity focused ultrasound (HIFU) for the treatment of liver and kidney tumours in a Western population

“…This has been known since the 1940s (Lynn et al, 1942); however, it is only recently that advances in imaging have allowed accurate placement of the acoustic focus and thus its clinical exploitation (Kennedy et al, 2003).…”