Temperature distributions during clinical scanned, focused ultrasound hyperthermia treatments

Abstract

In this study a scanned focused ultrasound (SFUS) system was used to heat 66 tumours at various anatomical locations in 52 patients. A total of 160 treatments were given. On average, temperatures were measured in 14 or 15 locations in the scanned volume. The time-averaged temperatures over the 30 min treatment period in the best treatment of each tumour were 44.0 +/- 2.4 degrees C (mean +/- SD) and 39.6 +/- 1.5 degrees C at the location of the highest and lowest sensor, respectively. On average, 39% of the sensors were above 42.5 degrees C. When only the cases that were judged to be good candidates for the hyperthermia device were analysed, 64% of the sensors reached a temperature over 42.5 degrees C with the highest temperature achieved being 45.9 +/- 2.3 degrees C and the lowest 40.7 +/- 1.4 degrees C. Although the system tested has many technical limitations (for example, fixed frequency, beam geometry and power during the scan cycle), the results demonstrate that therapeutic temperatures can be achieved in many tumours. Significantly better temperatures are expected when all of the theoretical potential of scanned focused ultrasound systems has been used.

Ultrasound drug targeting to tumors with thermosensitive liposomes

“…In a second series of testing, orthotopic EMT-6 tumors were heated: in this model, elevation of temperature to 41-43 o C was not as instantaneous (1-2 minutes), and throughout the course of heating (20 min), the output of the frequency generator had to be increased to maintain even heating. This particular observation was expected, as orthotopic tumors tend to be more heavily vascularized [21][22][23], perfusion is known to influence heat transfer, and vascular parameters in turn are influenced by heating [13,24]. In the footpad model, post HaT-DOX therapy, treated mice exhibited swollen feet and redness in the tumor, a response to treatment consistent with doxorubicin therapy seen in other models.…”

Focused ultrasound for treatment of bone tumours

“…Over the past decades, there have been numerous external ultrasound array systems for focused heating in the body, [22][23][24][25][26][27] including one system specifically optimized for small animal treatments [28]. At present, there are three commercial non-invasive ultrasound heating systems that have been integrated within either US or MR imaging systems for image-guidance of FUS treatments in humans: the ExAblate system (InSightec Ltd., Tirat Carmel, Israel) based on the General Electric MR platform [29,30]; the Sonalleve FUS system (Koninklijke Philips Electronics NV, Eindhoven, The Netherlands) based on the Phillips MR platform [31,32]; and the Haifu system (Model JC, Chongqing Haifu Medical Technology Co. Ltd., Chongqing, China) coupled with a B-type ultrasonography system [33].…”

Focused Extracorporeal Pyrotherapy

“…The transducer can be oriented from the longitudinal plane to the transverse plane, passing through all of the intermediate The use of the mechanical energy generated by focal ultrasound waves has been tested for many years since the discovery of the piezoelectricity phenomenon by Pierre and Jacques Curie [1], The experimental studies by Fry et al [2] on the nervous system and other studies by Hynynen et al [3,4], Hynynen [5] and ter Haar et al [6] opened the way to therapeutic applications of ultra sound.…”