Improved intercostal HIFU ablation using a phased array transducer based on Fermat's spiral and Voronoi tessellation: A numerical evaluation

Ramaekers, Pascal; Ries, Mario; Moonen, Chrit; Greef, Martijn de

doi:10.1002/mp.12082

Cited by 15 publications

(10 citation statements)

References 41 publications

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“…The literature that exists regarding the acoustic attenuation of ribs reported a wide range of data. There are some articles that specified rib attenuation, but the information regarding their source or measuring method is unknown. The values reported vary from 12–25 dB/cm‐MHz.…”

Section: Methodsmentioning

confidence: 99%

MRI‐compatible breast/rib phantom for evaluating ultrasonic thermal exposures

Menikou

Yiannakou

Yiallouras

et al. 2017

Robotics Computer Surgery

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Section: Methodsmentioning

confidence: 99%

MRI‐compatible breast/rib phantom for evaluating ultrasonic thermal exposures

Menikou

Yiannakou

Yiallouras

et al. 2017

Robotics Computer Surgery

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“…Ramaekers et al. designed a Voronoi-tessellated transducer based on Fermat’s spiral, compared the device to currently available clinical transducers, and showed that this design reduces acoustic energy deposit on the ribs and the energy density in the pre-focal zone ( 36 ).…”

Section: Introductionmentioning

confidence: 99%

A Novel Concept of a Phased-Array HIFU Transducer Optimized for MR-Guided Hepatic Ablation: Embodiment and First In-Vivo Studies

Lorton

M’Rad

et al. 2022

Front. Oncol.

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PurposeHigh-intensity focused ultrasound (HIFU) is challenging in the liver due to the respiratory motion and risks of near-/far-field burns, particularly on the ribs. We implemented a novel design of a HIFU phased-array transducer, dedicated to transcostal hepatic thermo-ablation. Due to its large acoustic window and strong focusing, the transducer should perform safely for this application.Material and MethodsThe new HIFU transducer is composed of 256 elements distributed on 5 concentric segments of a specific radius (either 100, 111, or 125 mm). It has been optimally shaped to fit the abdominal wall. The shape and size of the acoustic elements were optimized for the largest emitting surface and the lowest symmetry. Calibration tests have been conducted on tissue-mimicking gels under 3-T magnetic resonance (MR) guidance. In-vivo MR-guided HIFU treatment was conducted in two pigs, aiming to create thermal ablation deep in the liver without significant side effects. Imaging follow-up was performed at D0 and D7. Sacrifice and post-mortem macroscopic examination occurred at D7, with the ablated tissue being fixed for pathology.ResultsThe device showed −3-dB focusing capacities in a volume of 27 × 46 × 50 mm3 as compared with the numerical simulation volume of 18 × 48 × 60 mm3. The shape of the focal area was in millimeter-range agreement with the numerical simulations. No interference was detected between the HIFU sonication and the MR acquisition. In vivo, the temperature elevation in perivascular liver parenchyma reached 28°C above physiological temperature, within one breath-hold. The lesion was visible on Gd contrast-enhanced MRI sequences and post-mortem examination. The non-perfused volume was found in pig #1 and pig #2 of 8/11, 6/8, and 7/7 mm along the LR, AP, and HF directions, respectively. No rib burns or other near-field side effects were visually observed on post-mortem gross examination. High-resolution contrast-enhanced 3D MRI indicated a minor lesion on the sternum.ConclusionThe performance of this new HIFU transducer has been demonstrated in vitro and in vivo. The transducer meets the requirement to perform thermal lesions in deep tissues, without the need for rib-sparing means.

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“…It also remains to be established to which extent ultrasound can penetrate rib bone and how important it is to account for this phenomenon when modelling the propagation of ultrasound in the abdominal region. The ability to model the propagation of ultrasound through ribs and assess the importance of this relative to the case of locally reacting ribs [2] would be beneficial, particularly when studying the heat transfer mechanisms which lead to skin burns in HIFU patients [26]. There is therefore a requirement for resorting to multi-domain BEM to deal with the treatment planning complexities outlined above.…”

Section: Introductionmentioning

confidence: 99%

A fast full-wave solver for calculating ultrasound propagation in the body

et al. 2021

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Therapeutic ultrasound is a promising non-invasive method for inducing various beneficial biological effects in the human body. In cancer treatment applications, high-power ultrasound is focused at a target tissue volume to ablate the malignant tumour. The success of the procedure depends on the ability to accurately focus ultrasound and destroy the target tissue volume through coagulative necrosis whilst preserving the surrounding healthy tissue. Patient-specific treatment planning strategies are therefore being developed to increase the efficacy of such therapies, while reducing any damage to healthy tissue. These strategies require to use high-performance computing methods to solve ultrasound wave propagation in the body quickly and accurately. For realistic clinical scenarios, all numerical methods which employ volumetric meshes require several hours or days to solve the full-wave propagation on a computer cluster. The boundary element method (BEM) is an efficient approach for modelling the wave field because only the boundaries of the hard and soft tissue regions require discretisation. This paper presents a multiple-domain BEM formulation with a novel preconditioner for solving the Helmholtz transmission problem (HTP). This new formulation is efficient at high-frequencies and where highcontrast materials are present. Numerical experiments are performed to solve the HTP in multiple domains comprising: (i) human ribs, an idealised abdominal fat layer and liver tissue, (ii) a human kidney with a perinephric fat layer, exposed to the acoustic field generated by a high-intensity focused ultrasound (HIFU) array transducer. The time required to solve the equations associated with these problems on a single workstation is of the order of minutes. These results demonstrate the great potential of this new BEM formulation for accurately and quickly solving ultrasound wave propagation problems in large anatomical domains which is essential for developing treatment planning strategies.

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Improved intercostal HIFU ablation using a phased array transducer based on Fermat's spiral and Voronoi tessellation: A numerical evaluation

Cited by 15 publications

References 41 publications

MRI‐compatible breast/rib phantom for evaluating ultrasonic thermal exposures

MRI‐compatible breast/rib phantom for evaluating ultrasonic thermal exposures

A Novel Concept of a Phased-Array HIFU Transducer Optimized for MR-Guided Hepatic Ablation: Embodiment and First In-Vivo Studies

A fast full-wave solver for calculating ultrasound propagation in the body

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