HIFU Tissue Ablation: Concept and Devices

Abstract

High intensity focused ultrasound (HIFU) is rapidly gaining clinical acceptance as a technique capable of providing non-invasive heating and ablation for a wide range of applications. Usually requiring only a single session, treatments are often conducted as day case procedures, with the patient either fully conscious, lightly sedated or under light general anesthesia. HIFU scores over other thermal ablation techniques because of the lack of necessity for the transcutaneous insertion of probes into the target tissue. Sources placed either outside the body (for treatment of tumors or abnormalities of the liver, kidney, breast, uterus, pancreas brain and bone), or in the rectum (for treatment of the prostate), provide rapid heating of a target tissue volume, the highly focused nature of the field leaving tissue in the ultrasound propagation path relatively unaffected. Numerous extra-corporeal, transrectal and interstitial devices have been designed to optimize application-specific treatment delivery for the wide-ranging areas of application that are now being explored with HIFU. Their principle of operation is described here, and an overview of their design principles is given.

On the Behaviour of Living Cells under the Influence of Ultrasound

“…Ultrasound is well established as an imaging modality in medical diagnostics, and, more recently, its use has been extended to therapy. Ultrasonic therapeutic modalities in current clinical practice are high-intensity focussed ultrasound (HIFU) [1], extracorporeal shockwave lithotrypsy [2], ultrasound contrast agent-assisted drug delivery [3], and combinations of some of these modalities [4]. Acoustic cluster therapy has shown great promise in a mouse study [5].…”

“…Acoustic cluster therapy has shown great promise in a mouse study [5]. The aforementioned therapeutic modalities [1][2][3][4][5] are directed at modifying the macro-structural aspects of tissue. Claims have been made about pain relief with the aid of ultrasound equipment, but these are not supported by scientific evidence [6,7].…”

Pilot study: safety and effectiveness of simple ultrasound-guided high-intensity focused ultrasound ablating uterine leiomyoma with a diameter greater than 10 cm

“…Among the reasons for the good results in our study, the adoption of the USgHIFU system, which uses ultrasound and is equipped with an acoustic lens transducer, provides good realtime performance and higher conversion efficiency compared with the MRgHIFU system, which uses MRI as monitoring apparatus and is equipped with a multi-element phased array transducer. 17,18 Therefore, therapeutic efficacy was improved. Second, large leiomyoma are often accompanied by poor blood circulation, tissue denaturation, and sparing cellularity; 19,20 the energy from this system is easy to deposit directly into the leiomyoma.…”

Latest advances in combining gold nanomaterials with physical stimuli towards new responsive therapeutic and diagnostic strategies

“…The acoustic fluence required to produce cavitation is very high. HIFU [126][127][128], a therapeutic technique that uses a US intensity that is several orders of magnitude greater than that of standard US, is used to achieve the required acoustic fluence. However, internal cavitation is difficult to control.…”