Multi-frequency interstitial ultrasound applicator for conformal thermal therapy

Chopra, Rajiv; Luginbuhl, C.; Weymouth, Alfred J.; Foster, F. Stuart; Bronskill, Michael

doi:10.1109/ultsym.2001.991967

Cited by 6 publications

(7 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, these experimental studies of HIFU, with reported in situ ultrasound intensities of 200-2500 W/cm 2 for frequencies 1-4 MHz, do not indicate how cavitation activity interacts with ultrasound-induced heating for the unfocused ultrasound exposures employed in minimally-invasive bulk thermal ablation (Diederich et al 1999;Chopra et al 2001;Prat et al 2002;Makin et al 2005;. Ultrasound bulk ablation treatments cause tissue temperature elevation to occur more slowly, but in a larger tissue volume, than HIFU treatments.…”

Section: Introductionmentioning

confidence: 95%

“…This approach to ultrasound ablation, which has recently been developed and employed by several investigators (Diederich et al 1999;Chopra et al 2001;Prat et al 2002, has the potential to treat large tissue volumes at rates comparable to radiofrequency ablation and other minimally-invasive bulk ablation modalities. As with other thermal ablation methods, noninvasive monitoring and control of energy delivery, tissue temperature, and coagulation effects could improve the reliability of ablation, thus increasing the safety and efficacy of these minimally invasive treatments.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Mast

Salgaonkar

Karunakaran

et al. 2008

Ultrasound in Medicine & Biology

View full text Add to dashboard Cite

Acoustic emissions associated with cavitation and other bubble activity have previously been observed during ultrasound ablation experiments. Since detectable bubble activity may be related to temperature, tissue state, and sonication characteristics, these acoustic emissions are potentially useful for monitoring and control of ultrasound ablation. To investigate these relationships, ultrasound ablation experiments were performed with simultaneous measurements of acoustic emissions, tissue echogenicity, and tissue temperature, on fresh bovine liver. Ex vivo tissue was exposed to 0.9-3.3 s bursts of unfocused, continuous-wave, 3.10 MHz ultrasound from a miniaturized 32-element array, which performed B-scan imaging with the same piezoelectric elements during brief quiescent periods. Exposures employed pressure amplitudes of 0.8-1.4 MPa for exposure times of 6-20 min, sufficient to achieve significant thermal coagulation in all cases. Acoustic emissions received by a 1 MHz, unfocused passive cavitation detector, beamformed Aline signals acquired by the array, and tissue temperature detected by a needle thermocouple were sampled 0.3-1.1 times per second. Tissue echogenicity was quantified by the backscattered echo energy from a fixed region of interest within the treated zone. Acoustic emission levels were quantified from the spectra of signals measured by the passive cavitation detector, including subharmonic signal components at 1.55 MHz, broadband signal components within the band 0.3-1.1 MHz, and low-frequency components within the band 10-30 kHz. Tissue ablation rates, defined as the thermally ablated volumes per unit time, were assessed by quantitative analysis of digitally imaged, macroscopic tissue sections. Correlation analysis was performed among the averaged and time-dependent acoustic emissions in each band considered, B-mode tissue echogenicity, tissue temperature, and ablation rate. Ablation rate correlated significantly with broadband and low-frequency emissions, but was uncorrelated with subharmonic emissions. Subharmonic emissions were found to depend strongly on temperature in a nonlinear manner, with significant emissions occurring within different temperature ranges for each sonication amplitude. These results suggest potential roles for passive detection of acoustic emissions in guidance and control of bulk ultrasound ablation treatments.

show abstract

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Mast

Salgaonkar

Karunakaran

et al. 2008

Ultrasound in Medicine & Biology

View full text Add to dashboard Cite

show abstract

“…The site of heat deposition may then be displaced without mechanical movements. Several designs have been suggested 32,63,14 and treatment times are greatly reduced if phased arrays are used 64,65 . Therefore, to resolve the problems posed by treating esophageal tumours, Melodelima et al 36 tried using a 10 mm diameter cylindrical ultrasound applicator composed of 64 elementary transducers functioning at 4.55 MHz, and spread around the periphery of the cylinder (Figure 1c).…”

Section: Multi-element Cylindrical Transducersmentioning

confidence: 99%

Interstitial devices for minimally invasive thermal ablation by high-intensity ultrasound

Lafon

Melodelima

Salomir

et al. 2007

International Journal of Hyperthermia

View full text Add to dashboard Cite

2Interstitial devices for minimally invasive thermal ablation by high intensity ultrasound AbstractInterstitial ultrasound applicators have been proposed for treating deep-seated tumors that can not be reached with extracorporeal High Intensity Focused Ultrasound. In addition, interstitial ultrasound offers several advantages compared with conventional ablation technology (radiofrequency, microwaves, cryotherapy …) in terms of penetration, speed of coagulation, ability to direct and control the thermal lesion and compatibility with image monitoring. The ultrasound source is brought as close as possible to the target in order to minimize the effects of attenuation and phase aberration along the ultrasound pathway. The present paper is a review of the interstitial applicators that were described during the last decade in the literature. It is presented in three sections. The technical aspects common to all applicators are first described. For example, most described applicators are sideview applicators which active element is water-cooled and operates at rather high frequency (above 3MHz) in order to promote heating. Then the different potential techniques for monitoring treatment administered by the interstitial route are presented and illustrated through a review of imageguided interstitial thermal ablation. Three major techniques of imaging are used for guiding interstitial treatment: MRI, ultrasound and fluoroscopy. The third section will go further in detail on diverse described medical applications.3

show abstract

“…15,[22][23][24][25][26][27][28][29][30][31][32] Our group has been developing a MRI-controlled transurethral ultrasound therapy system for treatment of localized prostate cancer. 15,[32][33][34][35][36][37][38] Compared with transrectal HIFU, transurethral delivery enables the use of simple planar unfocused transducers within the prostate, avoiding the need to propagate sound through sensitive structures such as the rectal wall. The continuous delivery of ultrasound energy from multiple planar transducers enables a higher volumetric rate of coagulation compared with a focused approach.…”

Section: Introductionmentioning

confidence: 99%

Coagulation of human prostate volumes with MRI-controlled transurethral ultrasound therapy: Results in gel phantoms

et al. 2012

View full text Add to dashboard Cite

Purpose:The feasibility and safety of magnetic resonance imaging (MRI)-controlled transurethral ultrasound therapy were demonstrated recently in a preliminary human study in which a small subvolume of prostate tissue was treated prior to radical prostatectomy. Translation of this technology to full clinical use, however, requires the capability to generate thermal coagulation in a volume up to that of the prostate gland itself. The aim of this study was to investigate the parameters required to treat a full 3D human prostate accurately with a multi-element transurethral applicator and multiplanar MR temperature control. Methods: The approach was a combination of simulations (to select appropriate parameters) followed by experimental confirmation in tissue-mimicking phantoms. A ten-channel, MRI-compatible transurethral ultrasound therapy system was evaluated using six human prostate models (average volume: 36 cm 3 ) obtained from the preliminary human feasibility study. Real-time multiplanar MR thermometry at 3 T was used to control the spatial heating pattern in up to nine planes simultaneously. Treatment strategies incorporated both single (4.6 or 8.1 MHz) and dual (4.6 and 14.4 MHz) frequencies, as well as maximum acoustic surface powers of 10 or 20 W cm −2 . Results: Treatments at 4.6 MHz were capable of coagulating a volume equivalent to 97% of the prostate. Increasing power from 10 to 20 W cm −2 reduced treatment times by approximately 50% with full treatments taking 26 ± 3 min at a coagulation rate of 1.8 ± 0.4 cm 3 min −1 . A dual-frequency 4.6/14.4 MHz treatment strategy was shown to be the most effective configuration for achieving full human prostate treatment while maintaining good treatment accuracy for small treatment radii. The dual-frequency approach reduced overtreatment close to the prostate base and apex, confirming the simulations. Conclusions: This study reinforces the capability of MRI-controlled transurethral ultrasound therapy to treat full prostate volumes in a short treatment time with good spatial targeting accuracy and provides key parameters necessary for the next clinical trial.

show abstract

Multi-frequency interstitial ultrasound applicator for conformal thermal therapy

Cited by 6 publications

References 5 publications

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Acoustic Emissions During 3.1 MHz Ultrasound Bulk Ablation In Vitro

Interstitial devices for minimally invasive thermal ablation by high-intensity ultrasound

Coagulation of human prostate volumes with MRI-controlled transurethral ultrasound therapy: Results in gel phantoms

Contact Info

Product

Resources

About