A scanned, focused, multiple transducer ultrasonic system for localized hyperthermia treatments

Abstract

A commercial diagnostic ultrasound scanner (Octoson) was modified for performing hyperthermia treatments. The temperature elevations were induced in tissues by four large, focused ultrasonic transducers whose common focal zone was scanned along a computer controlled path as determined from B-scan images. The system is described and the results of preliminary tests demonstrating some of its capabilities are given. Extensive tests with canine thighs and kidneys were performed. The blood flow to the kidneys was controllable, and thus tumours having different blood perfusion rates could be simulated. The results showed that the system is capable of inducing a local temperature maximum deep in tissues (up to 10 cm was tested) and that tissues with high perfusion rates could be heated.

In vivo MR quantification of superparamagnetic iron oxide nanoparticle leakage during low‐frequency‐ultrasound‐induced blood–brain barrier opening in swine

“…In 100-ms sonications (either transcranially or with craniotomy), animals showed apparent BBB disruptions at off-target positions near the distal bone, suggesting energy accumulation caused by reflection. One possible solution to reduce such accumulation might be to adapt a system designed for ultrasound hyperthermia treatment (30,31) to steer the ultrasound pulse through a defined trajectory, thus avoiding the accumulation of energy at the same location.…”

MR temperature mapping of focused ultrasound surgery

“…The transient and profile data using Eqs. [10][11][12] to estimate both the diffusivity and characteristic radius of the acoustic beam.…”

“…Early experiments (9, 10) did not control the heat effected zone. By using diagnostic ultrasound to localize the focal spot, the control was improved; however, ultrasound does not image the heat or detect the focal lesions unless cavitation is generated to scatter the acoustic waves (11,12). Clinical studies using ultrasound localization have been performed in the eye (13); bladder, kidney, and liver tumors (14); and benign prostate disease using an intrarectal transducer (15).…”

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.…”