The use of a segmented transducer for rib sparing in HIFU treatments

Civale, John; Clarke, Robert L.; Rivens, Ian; Haar, Gail ter

doi:10.1016/j.ultrasmedbio.2006.06.005

Cited by 76 publications

(60 citation statements)

References 11 publications

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“…Using larger transducers to distribute the energy in the ultrasound beam path over a larger area might also help to reduce ribcage heating. Another option could be to design and use special transducers or phased arrays that focus the ultrasound beam between the ribs (34,35).…”

Section: Livermentioning

confidence: 99%

Current status and future potential of MRI‐guided focused ultrasound surgery

Jólesz

McDannold

2008

Magnetic Resonance Imaging

112

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The combination of the imaging abilities of magnetic resonance imaging (MRI) with the ability to delivery energy to targets deep in the body noninvasively with focused ultrasound presents a disruptive technology with the potential to significantly affect healthcare. MRI offers precise targeting, visualization, and quantification of temperature changes and the ability to immediately evaluate the treatment. By exploiting different mechanisms, focused ultrasound offers a range of therapies, ranging from thermal ablation to targeted drug delivery. This article reviews recent preclinical and tests clinical of this technology. WHILE ITS POTENTIAL has been recognized for decades (1-4), focused ultrasound (FUS) therapy has been in the incubation phase for a long time. Although it has been tested in numerous animal experiments, its widespread clinical realization has lagged, primarily due to the lack of intraprocedural accurate temperature monitoring. When the idea of MRI-guidance was introduced in connection with FUS and MRI thermometry during sonication was demonstrated (5,6), it was anticipated that MR-guided FUS surgery (MRgFUS) would be widely accepted clinically within a few years. Despite these early expectations, there has been relatively slow progress in the clinical implementation of MRgFUS.Early development concentrated primarily on breast tumors (benign fibroadenoma (7,8) and malignant breast cancer (9,10)). These early implementations of the MRgFUS technology motivated the improvement of transducer technology from single-element transducers to MRI-compatible multielement phase arrays (11). There was also significant progress in MRI thermometry and its use to monitor and control sonications. Importantly, too, methods were developed to robustly quantify temperature changes (12). At first, only 2D temperature maps were obtained by MRI to allow for accurate targeting of the beam (13). Later these thermal images were used to generate maps of the thermal dose (14) that could then be used to tailor the energy deposition using closed-loop feedback control (15). This preclinical work led to the development of the first commercial system by InSightec (Haifa, Israel), the Exablate 2000, the first implementation of a fully integrated MRgFUS system that combined a phased array transducer, a computer-controlled robotic positioner, and a workstation that integrated control based on MR thermometry.The early limited clinical trials of breast tumor treatment (8 -10,16,17) were followed by the first major clinical application: the noninvasive therapy of benign uterine fibroids (18,19). The successful Phase I trial was followed by a multicenter . These clinical trials led to the approval of this technology for the treatment of uterine fibroids in several countries, including the United States. Examples of MR thermometry and postablation imaging of a uterine fibroid ablation are shown in Figure 1.The success of uterine fibroid ablation has invigorated the entire field. Technology has rapidly improved and clinical applications ke...

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Section: Livermentioning

confidence: 99%

Current status and future potential of MRI‐guided focused ultrasound surgery

Jólesz

McDannold

2008

Magnetic Resonance Imaging

112

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“…Design of a linearly segmented transducer with elements arranged in strips and with selective deactivation of edge elements [23]. Similar to Civale et al [23] but using 2D phased array, selective deactivation of emitting elements that fall in the shadow (conical projection) of the ribs has been investigated [24,25].…”

Section: Introductionmentioning

confidence: 99%

“…Similar to Civale et al [23] but using 2D phased array, selective deactivation of emitting elements that fall in the shadow (conical projection) of the ribs has been investigated [24,25]. Adaptive focusing using multi-element transducer devices capable of working in both transmit and receive mode [26,27].…”

Section: Introductionmentioning

confidence: 99%

Spatio-temporal quantitative thermography of pre-focal interactions between high intensity focused ultrasound and the rib cage

Petrusca

Salomir

Manasseh

et al. 2015

International Journal of Hyperthermia

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Objective: The aim of this paper is to quantitatively investigate the thermal effects generated by the pre-focal interactions of a HIFU beam with a rib cage, in the context of minimally invasive transcostal therapy of liver malignancies. Materials and methods: HIFU sonications were produced by a phased-array MR-compatible transducer on Turkey muscle placed on a sheep thoracic cage specimen. The thoracic wall was positioned in the pre-focal zone 3.5 to 6.5 cm below the focus. Thermal monitoring was simultaneously performed using fluoroptic sensors inserted into the medullar cavity of the ribs and high resolution MR-thermometry (voxel: 1 Â 1 Â 5 mm 3 , four multi-planar slices). Results: MR-thermometry data indicated nearly isotropic distribution of the thermal energy at the ribs' surface. The temperature elevation at the focus was comparable with the pericostal temperature elevation around unprotected ribs, while being systematically inferior, by more than a factor of four on average, to the intra-medullar values. The spatial profiles of the pericostal and intra-medullar thermal build-up measurements could be smoothly connected using a Gaussian function. The dynamics of the post-sonication thermal relaxation as determined by fluoroptic measurements was demonstrated to be theoretically coherent with the experimental observations. Conclusion: The experimental findings motivate further efforts for the transfer towards clinical routine of effective rib-sparing strategies for hepatic HIFU.

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“…Bobkova et al [15] compared rib-sparing HIFU approaches to 'geometric' and 'diffraction' approaches. The earlier 'geometric' approaches switch off the transducers that are 'geometrically' obstructed by the ribs [16][17][18][19]. To account for the scattering, 'diffraction' approaches make use of the wave characteristics to further enhance focusing.…”

Section: Introductionmentioning

confidence: 99%

A novel sound-blocking structure based on the muffler principle for rib-sparing transcostal high-intensity focused ultrasound treatment

Chao

Hsu

et al. 2015

International Journal of Hyperthermia

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(2015) A novel sound-blocking structure based on the muffler principle for rib-sparing transcostal high-intensity focused ultrasound treatment, International Journal of Hyperthermia, 31:5, 507-527, DOI: 10.3109/02656736.2015 AbstractThe main challenge in transcostal high-intensity focused ultrasound therapy is minimising heat deposition in the ribs while ensuring that a sufficient dose is delivered to the target region. Current approaches rely on expensive multichannel phased-array systems to turn the individual transducer on and off according to either geometrical arrangements or complicated wave calculations. To protect the ribs from heating, the ultrasound energy must not only not reach the ribs, but must also not accumulate in front of the ribs. The research in this paper proposes a different approach, of attaching a sound-blocking structure in front of the rib cage with similar effects to those of an engine exhaust muffler. The sound-blocking structure is based on the muffler principle to prevent ultrasound energy from reaching the ribs and reduce the amount of energy reflected back to the applicator. Finite element simulations with a 0.5-MHz transducer of the overall sound fields and temperature distribution showed that the ultrasound pressure and energy level would decrease behind the novel sound-blocking structures, thereby resulting in a lower temperature at the ribs than at the tumour. Without the protecting structure, the rib temperature reached 104.19 C whereas with the structure it reached only 37.86 C. An experimental set-up using porcine ribs with a phantom was also developed to validate the concept, which showed that the rib temperature reached 73 C without protection within 1 min of ablation time whereas it reached 36.5 C with the device. The tumour region in the tests reached 51C and 49 C with and without protection, respectively.

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The use of a segmented transducer for rib sparing in HIFU treatments

Cited by 76 publications

References 11 publications

Current status and future potential of MRI‐guided focused ultrasound surgery

Current status and future potential of MRI‐guided focused ultrasound surgery

Spatio-temporal quantitative thermography of pre-focal interactions between high intensity focused ultrasound and the rib cage

A novel sound-blocking structure based on the muffler principle for rib-sparing transcostal high-intensity focused ultrasound treatment

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