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Zheng Y, Li C, Zhang C, He J, Jiang X, Ta D. Distinct thermal effect on biological tissues using subwavelength ultrasound metalens at megahertz. iScience 2023; 26:107929. [PMID: 37810209 PMCID: PMC10551838 DOI: 10.1016/j.isci.2023.107929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/21/2023] [Accepted: 09/12/2023] [Indexed: 10/10/2023] Open
Abstract
Ultrasound focusing plays an important role in biomedical therapy and diagnosis. Acoustic metalens has showcased remarkable focusing performance but yet to be implemented to the practical ultrasound therapeutic applications. We design a planar metalens operating at megahertz and experimentally demonstrate the distinct thermal effect on biological tissues induced by the high-resolution focusing. A prominent temperature rise of 50°C is experimentally observed in the biological phantom, with a much lower input ultrasound power of 4 W compared with the traditional methods. We further study the thermal effect on fresh porcine liver and investigate the morphological changes under different physical parameters. Visible lesions are observed in in vitro tissues at the lowest input ultrasound power of 2.6 W within 10 s. This study facilitates the practical biomedical application of acoustic metalens, providing a feasible approach for the precise, safe, and reliable therapeutic ultrasound with the simple and compact metalens.
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Affiliation(s)
- Yan Zheng
- Center for Biomedical Engineering, School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Chen Li
- Department of Ultrasound, Zhongshan Hospital, Fudan University, Shanghai 200032, P.R. China
| | - Chuanxin Zhang
- Center for Biomedical Engineering, School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Jiajie He
- Center for Biomedical Engineering, School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Xue Jiang
- Center for Biomedical Engineering, School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Dean Ta
- Center for Biomedical Engineering, School of Information Science and Technology, Fudan University, Shanghai 200433, China
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai 200040, China
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Yuldashev PV, Karzova MM, Kreider W, Rosnitskiy PB, Sapozhnikov OA, Khokhlova VA. "HIFU Beam:" A Simulator for Predicting Axially Symmetric Nonlinear Acoustic Fields Generated by Focused Transducers in a Layered Medium. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:2837-2852. [PMID: 33877971 PMCID: PMC8486313 DOI: 10.1109/tuffc.2021.3074611] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
"HIFU beam" is a freely available software tool that comprises a MATLAB toolbox combined with a user-friendly interface and binary executable compiled from FORTRAN source code (HIFU beam. (2021). Available: http://limu.msu.ru/node/3555?language=en). It is designed for simulating high-intensity focused ultrasound (HIFU) fields generated by single-element transducers and annular arrays with propagation in flat-layered media that mimic biological tissues. Numerical models incorporated in the simulator include evolution-type equations, either the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation or one-way Westervelt equation, for radially symmetric ultrasound beams in homogeneous and layered media with thermoviscous or power-law acoustic absorption. The software uses shock-capturing methods that allow for simulating strongly nonlinear acoustic fields with high-amplitude shocks. In this article, a general description of the software is given along with three representative simulation cases of ultrasound transducers and focusing conditions typical for therapeutic applications. The examples illustrate major nonlinear wave effects in HIFU fields including shock formation. Two examples simulate propagation in water, involving a single-element source (1-MHz frequency, 100-mm diameter, 90-mm radius of curvature) and a 16-element annular array (3-MHz frequency, 48-mm diameter, and 35-mm radius of curvature). The third example mimics the scenario of a HIFU treatment in a "water-muscle-kidney" layered medium using a source typical for abdominal HIFU applications (1.2-MHz frequency, 120-mm diameter, and radius of curvature). Linear, quasi-linear, and shock-wave exposure protocols are considered. It is intended that "HIFU beam" can be useful in teaching nonlinear acoustics; designing and characterizing high-power transducers; and developing exposure protocols for a wide range of therapeutic applications such as shock-based HIFU, boiling histotripsy, drug delivery, immunotherapy, and others.
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Karzova MM, Yuldashev PV, Khokhlova VA, Nartov FA, Morrison KP, Khokhlova TD. Dual-Use Transducer for Ultrasound Imaging and Pulsed Focused Ultrasound Therapy. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:2930-2941. [PMID: 33793399 PMCID: PMC8443157 DOI: 10.1109/tuffc.2021.3070528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pulsed focused ultrasound (pFUS) uses short acoustic pulses delivered at low duty cycle and moderate intensity to noninvasively apply mechanical stress or introduce disruption to tissue. Ultrasound-guided pFUS has primarily been used for inducing cavitation at the focus, with or without contrast agents, to promote drug delivery to tumors. When applied in tandem with contrast agents, pFUS is often administered using an ultrasound imaging probe, which has a small footprint and does not require a large acoustic window. The use of nonlinear pFUS without contrast agents was recently shown to be beneficial for localized tissue disruption, but required higher ultrasound pressure levels than a conventional ultrasound imaging probe could produce. In this work, we present the design of a compact dual-use 1-MHz transducer for ultrasound-guided pFUS without contrast agents. Nonlinear pressure fields that could be generated by the probe, under realistic power input, were simulated using the Westervelt equation. In water, fully developed shocks of 42-MPa amplitude and peak negative pressure of 8 MPa were predicted to form at the focus at 458-W acoustic power or 35% of the maximum reachable power of the transducer. In absorptive soft tissue, fully developed shocks formed at higher power (760 W or 58% of the maximum reachable power) with the shock amplitude of 33 MPa and peak negative pressure of 7.5 MPa. The electronic focus-steering capabilities of the array were evaluated and found to be sufficient to cover a target with dimensions of 19 mm in axial direction and 44 mm in transversal direction.
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Haqshenas SR, Gélat P, van 't Wout E, Betcke T, Saffari N. A fast full-wave solver for calculating ultrasound propagation in the body. ULTRASONICS 2021; 110:106240. [PMID: 32950757 DOI: 10.1016/j.ultras.2020.106240] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/20/2020] [Accepted: 08/25/2020] [Indexed: 05/23/2023]
Abstract
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 high-contrast 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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Affiliation(s)
- S R Haqshenas
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK; Department of Mathematics, University College London, London WC1H 0AY, UK.
| | - P Gélat
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK
| | - E van 't Wout
- Institute for Mathematical and Computational Engineering, School of Engineering and Faculty of Mathematics, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - T Betcke
- Department of Mathematics, University College London, London WC1H 0AY, UK
| | - N Saffari
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK
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Andreeva TA, Berkovich AE, Bykov NY, Kozyrev SV, Lukin AY. High-Intensity Focused Ultrasound: Heating and Destruction of Biological Tissue. TECHNICAL PHYSICS 2020. [DOI: 10.1134/s1063784220090030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Almekkawy M, Ebbini ES. The Optimization of Transcostal Phased Array Refocusing Using the Semidefinite Relaxation Method. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2020; 67:318-328. [PMID: 31567081 PMCID: PMC8651278 DOI: 10.1109/tuffc.2019.2944434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Tumors in organs partially obscured by the rib cage represent a challenge for high-intensity focused ultrasound (HIFU) therapy. The ribs distort the HIFU beams in a manner that reduces the focusing gain at the target, which could result in treatment-limiting collateral damage. In fact, skin burns are a common complication during the ablation of hepatic tumors. This problem can be addressed by employing optimal refocusing algorithms that are designed to achieve a specified focusing gain at the target while controlling the exposure to the ribs in the path of the HIFU beam. However, previously proposed optimal refocusing algorithms did not allow for the controlled transmission through the ribs. In this article, we introduce a new approach for refocusing that can more efficiently steer power toward the target while limiting the power deposition on the ribs. The approach utilizes the semidefinite relaxation (SDR) technique to approximate the original (nonconvex) optimization problem. An important advantage of the SDR-based method over previously proposed optimization methods is the control of the side lobes in the focal plane. The method also allows for specifying an acceptable level of exposure to the ribs. Simulation results using a 1-MHz spherical concave phased array focused on an inhomogeneous medium are presented to demonstrate the performance of the SDR refocusing approach. A finite-difference time-domain propagation model was used to model the propagation in the inhomogeneous tissues, including the ribs. Temperature simulations based on the inhomogeneous transient bioheat transfer equation (tBHTE) demonstrate the significance of the improvements in the focusing gain when using the limited power deposition (LPD) method. The results also demonstrate that the LPD method yields well-behaved array excitation vectors, realizable by currently existing drivers.
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Gu J, Jing Y. Simulation of the Second-Harmonic Ultrasound Field in Heterogeneous Soft Tissue Using a Mixed-Domain Method. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2019; 66:669-675. [PMID: 30640608 PMCID: PMC6492553 DOI: 10.1109/tuffc.2019.2892753] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A mixed-domain method (MDM) dubbed frequency-specific MDM (FSMDM) is introduced for the simulation of the second-harmonic ultrasound field in weakly heterogeneous media. The governing equation for the second harmonics is derived based on the quasi-linear theory. The speed of sound, nonlinear coefficient, and attenuation coefficient are all spatially varying functions in the equation. The fundamental frequency pressure field is first solved by the FSMDM and it is subsequently used as the source term for the second-harmonics equation. This equation can be again solved by the FSMDM to rapidly obtain the second-harmonic pressure field. Five 2-D cases, including one with a realistic human tissue map, are studied to systematically verify the proposed method. Results from the previously developed transient MDM are used as the benchmark solutions. Comparisons show that the two methods give similar results for all cases. More importantly, the FSMDM has a crucial advantage over the transient MDM in that it can be two orders of magnitude faster.
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Lundt J, Hall T, Rao A, Fowlkes JB, Cain C, Lee F, Xu Z. Coalescence of residual histotripsy cavitation nuclei using low-gain regions of the therapy beam during electronic focal steering. Phys Med Biol 2018; 63:225010. [PMID: 30418936 DOI: 10.1088/1361-6560/aaeaf3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Following collapse of a histotripsy cloud, residual microbubbles may persist for seconds, distributed throughout the focus. Their presence can attenuate and scatter subsequent pulses, hindering treatment speed and homogeneity. Previous studies have demonstrated use of separate low-amplitude (~1 MPa) pulses interleaved with histotripsy pulses to drive bubble coalescence (BC), significantly improving treatment speed without sacrificing homogeneity. We propose that by using electronic focal steering (EFS) to direct the therapy focus throughout specially-designed EFS sequences, it is possible to use low-gain regions of the therapy beam to accomplish BC during EFS without any additional acoustic sequence. First, to establish proof of principle for an isolated focus, a 50-foci EFS sequence was constructed with the first position isolated near the geometric focus and remaining positions distributed post-focally. EFS sequences were evaluated in tissue-mimicking phantoms with gas concentrations of 20% and 100% with respect to saturation. Results using an isolated focus demonstrated that at 20% gas concentration, 49 EFS pulses were sufficient to achieve BC in all samples for pulse repetition frequency (PRF) ⩽ 800 Hz and 84.1% ± 3.0% of samples at 5 kHz PRF. For phantoms prepared with 100% gas concentration, BC was achieved by 49 EFS pulses in 39.2% ± 4.7% of samples at 50 Hz PRF and 63.4% ± 15.3% of samples at 5 kHz. To show feasibility of using the EFS-BC method to ablate a large volume quickly, a 1000-foci EFS sequence covering a volume of approximately 27 ml was tested. Results indicate that the BC effect was similarly present. A treatment rate of 27 ± 6 ml min-1 was achieved, which is signficantly faster than standard histotripsy and ultrasound thermal ablation. This study demonstrates that histotripsy with EFS can achieve BC without employing a separate acoustic sequence which has the potential to accelerate large-volume ablation while minimizing energy deposition.
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Affiliation(s)
- Jonathan Lundt
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
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Lundt JE, Allen SP, Shi J, Hall TL, Cain CA, Xu Z. Non-invasive, Rapid Ablation of Tissue Volume Using Histotripsy. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:2834-2847. [PMID: 28935135 PMCID: PMC5693635 DOI: 10.1016/j.ultrasmedbio.2017.08.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/22/2017] [Accepted: 08/08/2017] [Indexed: 05/09/2023]
Abstract
Histotripsy is a non-invasive, non-thermal ablation technique that uses high-amplitude, focused ultrasound pulses to fractionate tissue via acoustic cavitation. The goal of this study was to illustrate the potential of histotripsy with electronic focal steering to achieve rapid ablation of a tissue volume at a rate matching or exceeding those of current clinical techniques (∼1-2 mL/min). Treatment parameters were established in tissue-mimicking phantoms and applied to ex vivo tissue. Six-microsecond pulses were delivered by a 250-kHz array. The focus was electrically steered to 1000 locations at a pulse repetition frequency of 200 Hz (0.12% duty cycle). Magnetic resonance imaging and histology of the treated tissue revealed a distinct region of necrosis in all samples. Mean lesion volume was 35.6 ± 4.3 mL, generated at 0.9-3.3 mL/min, a speed faster than that of any current ablation method for a large volume. These results suggest that histotripsy has the potential to achieve non-invasive, rapid, homogeneous ablation of a tissue volume.
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Affiliation(s)
- Jonathan E Lundt
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
| | - Steven P Allen
- Department Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Jiaqi Shi
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
| | - Timothy L Hall
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Charles A Cain
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Zhen Xu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
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Maxwell AD, Yuldashev PV, Kreider W, Khokhlova TD, Schade GR, Hall TL, Sapozhnikov OA, Bailey MR, Khokhlova VA. A Prototype Therapy System for Transcutaneous Application of Boiling Histotripsy. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2017; 64:1542-1557. [PMID: 28809681 PMCID: PMC5871228 DOI: 10.1109/tuffc.2017.2739649] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Boiling histotripsy (BH) is a method of focused ultrasound surgery that noninvasively applies millisecond-length pulses with high-amplitude shock fronts to generate liquefied lesions in tissue. Such a technique requires unique outputs compared to a focused ultrasound thermal therapy apparatus, particularly to achieve high in situ pressure levels through intervening tissue. This paper describes the design and characterization of a system capable of producing the necessary pressure to transcutaneously administer BH therapy through clinically relevant overlying tissue paths using pulses with duration up to 10 ms. A high-voltage electronic pulser was constructed to drive a 1-MHz focused ultrasound transducer to produce shock waves with amplitude capable of generating boiling within the pulse duration in tissue. The system output was characterized by numerical modeling with the 3-D Westervelt equation using boundary conditions established by acoustic holography measurements of the source field. Such simulations were found to be in agreement with directly measured focal waveforms. An existing derating method for nonlinear therapeutic fields was used to estimate in situ pressure levels at different tissue depths. The system was tested in ex vivo bovine liver samples to create BH lesions at depths up to 7 cm. Lesions were also created through excised porcine body wall (skin, adipose, and muscle) with 3-5 cm thickness. These results indicate that the system is capable of producing the necessary output for transcutaneous ablation with BH.
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He M, Zhong Z, Li X, Gong X, Wang Z, Li F. Effects of different hydrostatic pressure on lesions in ex vivo bovine livers induced by high intensity focused ultrasound. ULTRASONICS SONOCHEMISTRY 2017; 36:36-41. [PMID: 28069221 DOI: 10.1016/j.ultsonch.2016.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 06/06/2023]
Abstract
It is well-known that acoustic cavitation associated with the high intensity focused ultrasound (HIFU) treatment often would change the morphology and size of lesions in its treatment. In most studies reported in literature, high ambient hydrostatic pressure was used to suppress the cavitation completely. Investigation of the effects by varying the ambient hydrostatic pressure (Pstat) is still lacking. In this paper, the effects of HIFU on lesions in ex vivo bovine liver specimens under various Pstat are systematically investigated. A 1MHz HIFU transducer, with an aperture diameter of 70mm and a focal length of 55mm, was used to generate two groups US exposure of different acoustic intensities and exposure time (6095W/cm2×8s and 9752W/cm2×5s), while keeping the same acoustic energies per unit area (48760J/cm2). The peak acoustic negative pressures (p-) of the two groups were p1-=9.58MPa and p2-=10.82MPa, respectively, with the difference pd-=p2--p1-=1.24MPa. A passive cavitation detection (PCD) was used to monitor the ultrasonic cavitation signal during exposure of the two groups. The US exposures were done under the following ambient hydrostatic pressures, Pstat: atmospheric pressure, 0.5MPa, 1.0MPa, 1.5MPa, 2.0MPa, 2.5MPa and3.0MPa, respectively. The result of PCD showed that there was a statistically significant increase above background noise level in broadband emissions at dose of 9752W/cm2×5s, but not at dose of 6095W/cm2×8s under atmospheric pressure; i.e., the acoustic cavitation took place for p2- but not for p1- when under atmospheric pressure. The results also showed that there was no statistically difference of the morphology and size of lesions for 6095W/cm2×8s exposure under the aforementioned different ambient hydrostatic pressures. But the lesions generated at 9752W/cm2×5s exposure under Pstat=atmospheric pressure, 0.5MPa, 1.0MPa (all of them are less than pd-), were larger than those under 1.5MPa, 2.0MPa, 2.5MPa and 3.0MPa (all of them are over than pd-) which were consistence with 6095W/cm2×8s group. It was concluded that when Pstat>pd-, the acoustic cavitation was suppressed and prompted that there was no need to elevate Pstat higher than p- to suppress the acoustic cavitation in tissue, just need Pstat higher than pd-.
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Affiliation(s)
- Min He
- State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing 400016, PR China
| | - Zhiqiang Zhong
- State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing 400016, PR China
| | - Xing Li
- State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing 400016, PR China
| | - Xiaobo Gong
- National Engineering Research Center of Ultrasound Medicine, Chongqing 401121, PR China
| | - Zhibiao Wang
- State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing 400016, PR China
| | - Faqi Li
- State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, College of Biomedical Engineering, Chongqing Key Laboratory of Biomedical Engineering, Chongqing Medical University, Chongqing 400016, PR China.
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van 't Wout E, Gélat P, Betcke T, Arridge S. A fast boundary element method for the scattering analysis of high-intensity focused ultrasound. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 138:2726-37. [PMID: 26627749 DOI: 10.1121/1.4932166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
High-intensity focused ultrasound (HIFU) techniques are promising modalities for the non-invasive treatment of cancer. For HIFU therapies of, e.g., liver cancer, one of the main challenges is the accurate focusing of the acoustic field inside a ribcage. Computational methods can play an important role in the patient-specific planning of these transcostal HIFU treatments. This requires the accurate modeling of acoustic scattering at ribcages. The use of a boundary element method (BEM) is an effective approach for this purpose because only the boundaries of the ribs have to be discretized instead of the standard approach to model the entire volume around the ribcage. This paper combines fast algorithms that improve the efficiency of BEM specifically for the high-frequency range necessary for transcostal HIFU applications. That is, a Galerkin discretized Burton-Miller formulation is used in combination with preconditioning and matrix compression techniques. In particular, quick convergence is achieved with the operator preconditioner that has been designed with on-surface radiation conditions for the high-frequency approximation of the Neumann-to-Dirichlet map. Realistic computations of acoustic scattering at 1 MHz on a human ribcage model demonstrate the effectiveness of this dedicated BEM algorithm for HIFU scattering analysis.
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Affiliation(s)
- Elwin van 't Wout
- Department of Computer Science, University College London, London, United Kingdom
| | - Pierre Gélat
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Timo Betcke
- Department of Mathematics, University College London, London, United Kingdom
| | - Simon Arridge
- Department of Computer Science, University College London, London, United Kingdom
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Gavrilov LR, Sapozhnikov OA, Khokhlova VA. Spiral arrangement of elements of two-dimensional ultrasonic therapeutic arrays as a way of increasing the intensity at the focus. ACTA ACUST UNITED AC 2015. [DOI: 10.3103/s106287381510010x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Sapozhnikov OA, Tsysar SA, Khokhlova VA, Kreider W. Acoustic holography as a metrological tool for characterizing medical ultrasound sources and fields. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 138:1515-32. [PMID: 26428789 PMCID: PMC4575327 DOI: 10.1121/1.4928396] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/26/2015] [Accepted: 07/30/2015] [Indexed: 05/07/2023]
Abstract
Acoustic holography is a powerful technique for characterizing ultrasound sources and the fields they radiate, with the ability to quantify source vibrations and reduce the number of required measurements. These capabilities are increasingly appealing for meeting measurement standards in medical ultrasound; however, associated uncertainties have not been investigated systematically. Here errors associated with holographic representations of a linear, continuous-wave ultrasound field are studied. To facilitate the analysis, error metrics are defined explicitly, and a detailed description of a holography formulation based on the Rayleigh integral is provided. Errors are evaluated both for simulations of a typical therapeutic ultrasound source and for physical experiments with three different ultrasound sources. Simulated experiments explore sampling errors introduced by the use of a finite number of measurements, geometric uncertainties in the actual positions of acquired measurements, and uncertainties in the properties of the propagation medium. Results demonstrate the theoretical feasibility of keeping errors less than about 1%. Typical errors in physical experiments were somewhat larger, on the order of a few percent; comparison with simulations provides specific guidelines for improving the experimental implementation to reduce these errors. Overall, results suggest that holography can be implemented successfully as a metrological tool with small, quantifiable errors.
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Affiliation(s)
- Oleg A Sapozhnikov
- Department of Acoustics, Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Sergey A Tsysar
- Department of Acoustics, Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Vera A Khokhlova
- Department of Acoustics, Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Wayne Kreider
- Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, 1013 Northeast 40th Street, Seattle, Washington 98105, USA
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de Greef M, Schubert G, Wijlemans JW, Koskela J, Bartels LW, Moonen CTW, Ries M. Intercostal high intensity focused ultrasound for liver ablation: The influence of beam shaping on sonication efficacy and near-field risks. Med Phys 2015; 42:4685-97. [DOI: 10.1118/1.4925056] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Gélat P, Ter Haar G, Saffari N. An assessment of the DORT method on simple scatterers using boundary element modelling. Phys Med Biol 2015; 60:3715-30. [DOI: 10.1088/0031-9155/60/9/3715] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Petrusca L, Salomir R, Manasseh G, Becker CD, Terraz S. Spatio-temporal quantitative thermography of pre-focal interactions between high intensity focused ultrasound and the rib cage. Int J Hyperthermia 2015; 31:421-32. [PMID: 25753370 DOI: 10.3109/02656736.2015.1009501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
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 × 1 × 5 mm3, 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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Affiliation(s)
- Lorena Petrusca
- Hepatobiliary Interventional Radiology, Faculty of Medicine, University of Geneva , Geneva, Switzerland
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Khokhlova VA, Fowlkes JB, Roberts WW, Schade GR, Xu Z, Khokhlova TD, Hall TL, Maxwell AD, Wang YN, Cain CA. Histotripsy methods in mechanical disintegration of tissue: towards clinical applications. Int J Hyperthermia 2015; 31:145-62. [PMID: 25707817 PMCID: PMC4448968 DOI: 10.3109/02656736.2015.1007538] [Citation(s) in RCA: 187] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In high intensity focused ultrasound (HIFU) therapy, an ultrasound beam is focused within the body to locally affect the targeted site without damaging intervening tissues. The most common HIFU regime is thermal ablation. Recently there has been increasing interest in generating purely mechanical lesions in tissue (histotripsy). This paper provides an overview of several studies on the development of histotripsy methods toward clinical applications. Two histotripsy approaches and examples of their applications are presented. In one approach, sequences of high-amplitude, short (microsecond-long), focused ultrasound pulses periodically produce dense, energetic bubble clouds that mechanically disintegrate tissue. In an alternative approach, longer (millisecond-long) pulses with shock fronts generate boiling bubbles and the interaction of shock fronts with the resulting vapour cavity causes tissue disintegration. Recent preclinical studies on histotripsy are reviewed for treating benign prostatic hyperplasia (BPH), liver and kidney tumours, kidney stone fragmentation, enhancing anti-tumour immune response, and tissue decellularisation for regenerative medicine applications. Potential clinical advantages of the histotripsy methods are discussed. Histotripsy methods can be used to mechanically ablate a wide variety of tissues, whilst selectivity sparing structures such as large vessels. Both ultrasound and MR imaging can be used for targeting and monitoring the treatment in real time. Although the two approaches utilise different mechanisms for tissue disintegration, both have many of the same advantages and offer a promising alternative method of non-invasive surgery.
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Affiliation(s)
- Vera A Khokhlova
- Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington , Seattle, Washington , USA
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Gélat P, Ter Haar G, Saffari N. A comparison of methods for focusing the field of a HIFU array transducer through human ribs. Phys Med Biol 2014; 59:3139-71. [PMID: 24861888 DOI: 10.1088/0031-9155/59/12/3139] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A forward model, which predicts the scattering by human ribs of a multi-element high-intensity focused ultrasound transducer, was used to investigate the efficacy of a range of focusing approaches described in the literature. This forward model is based on the boundary element method and was described by Gélat et al (2011 Phys. Med. Biol. 56 5553-81; 2012 Phys. Med. Biol. 57 8471-97). The model has since been improved and features a complex surface impedance condition at the surface of the ribs. The inverse problem of focusing through the ribs was implemented on six transducer array-rib topologies and five methods of focusing were investigated, including spherical focusing, binarized apodization based on geometric ray tracing, phase conjugation and the decomposition of the time-reversal operator method. The excitation frequency was 1 MHz and the array was of spherical-section type. Both human and idealized rib topologies were considered. The merit of each method of focusing was examined. It was concluded that the constrained optimization approach offers greater potential than the other focusing methods in terms of maximizing the ratio of acoustic pressure magnitudes at the focus to those on the surface of the ribs whilst taking full advantage of the dynamic range of the phased array.
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Affiliation(s)
- P Gélat
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK. Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
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Petrusca L, Auboiroux V, Goget T, Viallon M, Muller A, Gross P, Becker CD, Salomir R. A nonparametric temperature controller with nonlinear negative reaction for multi-point rapid MR-guided HIFU ablation. IEEE TRANSACTIONS ON MEDICAL IMAGING 2014; 33:1324-1337. [PMID: 24893259 DOI: 10.1109/tmi.2014.2310704] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Magnetic resonance-guided high intensity focused ultrasound (MRgHIFU) is a noninvasive method for thermal ablation, which exploits the capabilities of magnetic resonance imaging (MRI) for excellent visualization of the target and for near real-time thermometry. Oncological quality of ablation may be obtained by volumetric sonication under automatic feedback control of the temperature. For this purpose, a new nonparametric (i.e., model independent) temperature controller, using nonlinear negative reaction, was designed and evaluated for the iterated sonication of a prescribed pattern of foci. The main objective was to achieve the same thermal history at each sonication point during volumetric MRgHIFU. Differently sized linear and circular trajectories were investigated ex vivo and in vivo using a phased-array HIFU transducer. A clinical 3T MRI scanner was used and the temperature elevation was measured in five slices simultaneously with a voxel size of 1 ×1 ×5 mm(3) and temporal resolution of 4 s. In vivo results indicated a similar thermal history of each sonicated focus along the prescribed pattern, that was 17.3 ± 0.5 °C as compared to 16 °C prescribed temperature elevation. The spatio-temporal control of the temperature also enabled meaningful comparison of various sonication patterns in terms of dosimetry and near-field safety. The thermal build-up tended to drift downwards in the HIFU transducer with a circular scan.
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Kim Y, Vlaisavljevich E, Owens GE, Allen SP, Cain CA, Xu Z. In vivotranscostal histotripsy therapy without aberration correction. Phys Med Biol 2014; 59:2553-68. [DOI: 10.1088/0031-9155/59/11/2553] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Lin J, Liu X, Gong X, Ping Z, Wu J. Computational study on the propagation of strongly focused nonlinear ultrasound in tissue with rib-like structures. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2013; 134:1702-1714. [PMID: 23927211 DOI: 10.1121/1.4812897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The presence of a rib cage is a significant hindrance to the potential applications of focused ultrasound as a noninvasive extracorporeal surgery modality for various internal organs. Here the influence of ribs on the propagation of strongly focused high-intensity nonlinear ultrasound beam inside the body is studied. Based on the spheroidal beam equation, a three-dimensional numerical algorithm is developed to solve the nonlinear acoustic field generated by a focused ultrasonic transducer with a large aperture angle. Idealized ribs, of rectangular cross sectional, with high absorption and impedance, and various dimensions, are used to simulate human anatomical configurations. The changes in the spatial distribution of acoustic intensity and the reduction of the acoustic pressure amplitude and heat deposition rate due to the presence of "ribs" are investigated. It is somewhat surprising that in some cases, the axial peak positions shift less than 2 mm and more than 80% of the sound energy can propagate through the space of the rib cage in the strongly focused sound field. This study also includes quantitative analyses of the effects of different rib configurations and transducers of various f-numbers. The results can be used as reference information for further study and clinical applications.
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Affiliation(s)
- Jiexing Lin
- Key Lab of Modern Acoustics, Institute of Acoustics, Nanjing University, Nanjing 210093, People's Republic of China
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