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Delattre V, Cambronero S, Chen Y, Haar GT, Rivens I, Polton G, Lafon C, Melodelima D. In vivo exposure of the bladder using a non-invasive high intensity focused ultrasound toroidal transducer. ULTRASONICS 2024; 138:107239. [PMID: 38211366 DOI: 10.1016/j.ultras.2024.107239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/15/2023] [Accepted: 01/01/2024] [Indexed: 01/13/2024]
Abstract
A toroidal high-intensity focused ultrasound (HIFU) transducer was used to expose normal bladder wall tissues non-invasively in vivo in a porcine model in order to investigate the potential to treat bladder tumors. The transducer was divided into 32 concentric rings with equal surface areas, operating at 2.5 MHz. Eight animals were split into two groups of 4. In the first group, post-mortem evaluation was performed immediately after ultrasound exposure. In the second group, animals survived for up to seven days before post-mortem evaluation. The ultrasound imaging guided HIFU device was hand-held during the procedure using optical tracking to ensure correct targeting. One thermal lesion in each animal was created using a 40 s exposure at 80 acoustic Watts (free-field) in the trigone region of the bladder wall. The average (±Standard Deviation) abdominal wall and bladder wall thicknesses were 10.3 ± 1.4 mm and 1.1 ± 0.4 mm respectively. The longest and shortest axes of the HIFU ablations were 7.7 ± 2.9 mm and 6.0 ± 1.8 mm, respectively, resulting in an ablation of the whole thickness of the bladder wall in most cases. Ablation were performed at an average depth (distance from the skin surface to the centre of the HIFU lesion) of 42.5 ± 3.8 mm and extended throughout the thickness of the bladder. There were two cases of injury to tissues immediately adjacent to the bladder wall but without signs of perforation, as confirmed by histological analysis. Non-invasive HIFU ablation using a hand-held toroidal transducer was successfully performed to destroy regions of the bladder wall in vivo.
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Affiliation(s)
- Victor Delattre
- LabTAU, INSERM, Centre Léon Bérard, Université Claude Bernard Lyon 1, F-69003, Lyon, France.
| | - Sophie Cambronero
- LabTAU, INSERM, Centre Léon Bérard, Université Claude Bernard Lyon 1, F-69003, Lyon, France
| | - Yao Chen
- LabTAU, INSERM, Centre Léon Bérard, Université Claude Bernard Lyon 1, F-69003, Lyon, France
| | - Gail Ter Haar
- Joint Department of Physics, Institute of Cancer Research and Royal Marsden Hospital NHS Trust, Sutton, Surrey, UK
| | - Ian Rivens
- Joint Department of Physics, Institute of Cancer Research and Royal Marsden Hospital NHS Trust, Sutton, Surrey, UK
| | - Gerry Polton
- North Downs Specialist Referrals, Bletchingley, Surrey, UK
| | - Cyril Lafon
- LabTAU, INSERM, Centre Léon Bérard, Université Claude Bernard Lyon 1, F-69003, Lyon, France; Joint Department of Physics, Institute of Cancer Research and Royal Marsden Hospital NHS Trust, Sutton, Surrey, UK
| | - David Melodelima
- LabTAU, INSERM, Centre Léon Bérard, Université Claude Bernard Lyon 1, F-69003, Lyon, France
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Zubair M, Adams MS, Diederich CJ. Deployable ultrasound applicators for endoluminal delivery of volumetric hyperthermia. Int J Hyperthermia 2021; 38:1188-1204. [PMID: 34376103 DOI: 10.1080/02656736.2021.1936216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
PURPOSE To investigate the design of an endoluminal deployable ultrasound applicator for delivering volumetric hyperthermia to deep tissue sites as a possible adjunct to radiation and chemotherapy. METHOD This study considers an ultrasound applicator consisting of two tubular transducers situated at the end of a catheter assembly, encased within a distensible conical shaped balloon-based reflector that redirects acoustic energy distally into the tissue. The applicator assembly can be inserted endoluminally or laparoscopically in a compact form and expanded after delivery to the target site. Comprehensive acoustic and biothermal simulations and parametric studies were employed in generalized 3D and patient-specific pancreatic head and body tumor models to characterize the acoustic performance and evaluate heating capabilities of the applicator by investigating the device at a range of operating frequencies, tissue acoustic and thermal properties, transducer configurations, power modulation, applicator positioning, and by analyzing the resultant 40, 41, and 43 °C isothermal volumes and penetration depth of the heating volume. Intensity distributions and volumetric temperature contours were calculated to define moderate hyperthermia boundaries. RESULTS Parametric studies demonstrated the frequency selection to control volume and depth of therapeutic heating from 62 to 22 cm3 and 4 to 2.6 cm as frequency ranges from 1 MHz to 4.7 MHz, respectively. Width of the heating profile tracks closely with the aperture. Water cooling within the reflector balloon was effective in controlling temperature to 37 °C maximum within the luminal wall. Patient-specific studies indicated that applicators with extended OD in the range of 3.6-6.2 cm with 0.5-1 cm long and 1 cm OD transducers can heat volumes of 1.1-7 cm3, 3-26 cm3, and 3.3-37.4 cm3 of pancreatic body and head tumors above 43, 41, and 40 °C, respectively. CONCLUSION In silico studies demonstrated the feasibility of combining endoluminal ultrasound with an integrated expandable balloon reflector for delivering volumetric hyperthermia in regions adjacent to body lumens and cavities.
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Affiliation(s)
- Muhammad Zubair
- Thermal Therapy Research Group, Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Matthew S Adams
- Thermal Therapy Research Group, Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Chris J Diederich
- Thermal Therapy Research Group, Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
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Development of a Simple In Vitro Artery Model and an Evaluation of the Impact of Pulsed Flow on High-Intensity Focused Ultrasound Ablation. Ing Rech Biomed 2021. [DOI: 10.1016/j.irbm.2020.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Adams MS, Diederich CJ. Deployable cylindrical phased-array applicator mimicking a concentric-ring configuration for minimally-invasive delivery of therapeutic ultrasound. Phys Med Biol 2019; 64:125001. [PMID: 31108478 DOI: 10.1088/1361-6560/ab2318] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A novel design for a deployable catheter-based ultrasound applicator for endoluminal and laparoscopic intervention is introduced. By combining a 1D cylindrical ring phased array with an expandable paraboloid or conical-shaped balloon-based reflector, the applicator can be controllably collapsed for compact delivery and deployed to mimic a forward-firing larger diameter concentric ring array with tight focusing and electronic steering capabilities in depth. Comprehensive acoustic and biothermal parametric studies were employed to characterize the capabilities of the applicator design as a function of transducer dimensions, phased array configuration, and balloon reflector geometry. Modeling results indicate that practical balloon sizes (43-57 mm expanded diameter), transducer array configurations (e.g. 1.5 MHz, 10 mm OD × 20 mm length, 8 or 16 array elements), and sonication durations (30 s) are capable of producing spatially-localized acoustic intensity focal patterns and ablative thermal lesions (width: 2.8-4.8 mm; length: 5.3-40.1 mm) in generalized soft tissue across a 5-100 mm depth range. Larger focal intensity gain magnitudes and narrower focal dimensions are attainable using paraboloid-shaped balloon reflectors with natural geometric focal depths of 25-55 mm, whereas conical-shaped reflectors (angled 45-55°) produce broader foci and extend electronic steering range in depth. A proof-of-concept phased array applicator assembly was fabricated and characterized using hydrophone and radiation force balance measurements and demonstrated good agreement with simulation. The results of this study suggest that combining small diameter cylindrical phased arrays with expandable balloon reflectors can enhance minimally invasive ultrasound-based intervention by augmenting achievable focal gains and penetration depths with dynamic adjustment of treatment depth.
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Adams MS, Scott SJ, Salgaonkar VA, Sommer G, Diederich CJ. Thermal therapy of pancreatic tumours using endoluminal ultrasound: Parametric and patient-specific modelling. Int J Hyperthermia 2016; 32:97-111. [PMID: 27097663 DOI: 10.3109/02656736.2015.1119892] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE The aim of this study is to investigate endoluminal ultrasound applicator configurations for volumetric thermal ablation and hyperthermia of pancreatic tumours using 3D acoustic and biothermal finite element models. MATERIALS AND METHODS Parametric studies compared endoluminal heating performance for varying applicator transducer configurations (planar, curvilinear-focused, or radial-diverging), frequencies (1-5 MHz), and anatomical conditions. Patient-specific pancreatic head and body tumour models were used to evaluate feasibility of generating hyperthermia and thermal ablation using an applicator positioned in the duodenal or stomach lumen. Temperature and thermal dose were calculated to define ablation (> 240 EM(43 °C)) and moderate hyperthermia (40-45 °C) boundaries, and to assess sparing of sensitive tissues. Proportional-integral control was incorporated to regulate maximum temperature to 70-80 °C for ablation and 45 °C for hyperthermia in target regions. RESULTS Parametric studies indicated that 1-3 MHz planar transducers are the most suitable for volumetric ablation, producing 5-8 cm(3) lesion volumes for a stationary 5-min sonication. Curvilinear-focused geometries produce more localised ablation to 20-45 mm depth from the GI tract and enhance thermal sparing (T(max) < 42 °C) of the luminal wall. Patient anatomy simulations show feasibility in ablating 60.1-92.9% of head/body tumour volumes (4.3-37.2 cm(3)) with dose < 15 EM(43 °C) in the luminal wall for 18-48 min treatment durations, using 1-3 applicator placements in GI lumen. For hyperthermia, planar and radial-diverging transducers could maintain up to 8 cm(3) and 15 cm(3) of tissue, respectively, between 40-45 °C for a single applicator placement. CONCLUSIONS Modelling studies indicate the feasibility of endoluminal ultrasound for volumetric thermal ablation or hyperthermia treatment of pancreatic tumour tissue.
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Affiliation(s)
- Matthew S Adams
- a Thermal Therapy Research Group, University of California , San Francisco , California .,b University of California, Berkeley - University of California, San Francisco Graduate Program in Bioengineering , California , and
| | - Serena J Scott
- a Thermal Therapy Research Group, University of California , San Francisco , California
| | - Vasant A Salgaonkar
- a Thermal Therapy Research Group, University of California , San Francisco , California
| | - Graham Sommer
- c Stanford Medical Center , Stanford , California , USA
| | - Chris J Diederich
- a Thermal Therapy Research Group, University of California , San Francisco , California .,b University of California, Berkeley - University of California, San Francisco Graduate Program in Bioengineering , California , and
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Salgaonkar VA, Diederich CJ. Catheter-based ultrasound technology for image-guided thermal therapy: current technology and applications. Int J Hyperthermia 2015; 31:203-15. [PMID: 25799287 DOI: 10.3109/02656736.2015.1006269] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Catheter-based ultrasound (CBUS) is applied to deliver minimally invasive thermal therapy to solid cancer tumours, benign tissue growth, vascular disease, and tissue remodelling. Compared to other energy modalities used in catheter-based surgical interventions, unique features of ultrasound result in conformable and precise energy delivery with high selectivity, fast treatment times, and larger treatment volumes. We present a concise review of CBUS technology being currently utilized in animal and clinical studies or being developed for future applications. CBUS devices have been categorised into interstitial, endoluminal and endovascular/cardiac applications. Basic applicator designs, site-specific evaluations and possible treatment applications have been discussed in brief. Particular emphasis has been given to ablation studies that incorporate image guidance for applicator placement, therapy monitoring, feedback control, and post-procedure assessment. Examples of devices included here span the entire spectrum of the development cycle from preliminary simulation-based design studies to implementation in clinical investigations. The use of CBUS under image guidance has the potential for significantly improving precision and applicability of thermal therapy delivery.
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Affiliation(s)
- Vasant A Salgaonkar
- Department of Radiation Oncology, University of California , San Francisco, California , USA
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Caloone J, Huissoud C, Vincenot J, Kocot A, Dehay C, Chapelon JY, Rudigoz RC, Melodelima D. High-intensity focused ultrasound applied to the placenta using a toroidal transducer: a preliminary ex-vivo study. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2015; 45:313-319. [PMID: 24723334 DOI: 10.1002/uog.13374] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 03/04/2014] [Accepted: 03/14/2014] [Indexed: 06/03/2023]
Abstract
OBJECTIVE To demonstrate in an ex-vivo model the feasibility of applying high-intensity focused ultrasound (HIFU) using a toroidal transducer for the creation of placental lesions. METHODS In this study we used a toroidal transducer, composed of 32 ring-shaped emitters with an ultrasound probe at the center, operating at a frequency of 2.5 MHz. We examined 45 human placentae, following either normal vaginal delivery or medical termination of pregnancy between 17 and 40 gestational weeks. First, the attenuation coefficients of 12 human placentae were measured and integrated into a numerical model for simulating HIFU lesions. Then, using acoustic parameters from this preliminary study, we performed ex-vivo experiments with 33 human placentae, each overlain with an animal abdominal wall to simulate the maternal wall. We created single HIFU lesions in 25 of these placentae, and a series of six juxtaposed lesions in eight, studying these both sonographically and macroscopically. RESULTS Human placental attenuation coefficients of the 12 human placentae ranged from 0.072 to 0.098 Np/cm/MHz, according to gestational age. The 25 single HIFU lesions created had an average diameter of 7.1 ± 3.2 mm and an average depth of 8.2 ± 3.1 mm. The average diameter of the eight series of six juxtaposed HIFU lesions was 23.0 ± 5.0 mm and the average depth was 11.0 ± 4.7 mm. The average thickness of the abdominal walls was 10.5 ± 1.8 mm. No lesions or damage were observed in intervening tissues. CONCLUSION This study demonstrates, using an ex-vivo model, the feasibility, reproducibility, harmlessness and effectiveness of HIFU applied to the human placenta.
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Affiliation(s)
- J Caloone
- Inserm, U1032, LabTau, Lyon, France; Université de Lyon, Lyon, France; Department of Obstetrics and Gynecology, Croix Rousse University Hospital, Lyon, France
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N’Djin WA, Burtnyk M, Lipsman N, Bronskill M, Kucharczyk W, Schwartz ML, Chopra R. Active MR-temperature feedback control of dynamic interstitial ultrasound therapy in brain:In vivoexperiments and modeling in native and coagulated tissues. Med Phys 2014; 41:093301. [DOI: 10.1118/1.4892923] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Rata M, Birlea V, Murillo A, Paquet C, Cotton F, Salomir R. Endoluminal MR-guided ultrasonic applicator embedding cylindrical phased-array transducers and opposed-solenoid detection coil. Magn Reson Med 2014; 73:417-26. [PMID: 24478117 DOI: 10.1002/mrm.25099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 11/18/2013] [Accepted: 12/07/2013] [Indexed: 12/20/2022]
Abstract
PURPOSE MR-guided high-intensity contact ultrasound (HICU) was suggested as an alternative therapy for esophageal and rectal cancer. To offer high-quality MR guidance, two prototypes of receive-only opposed-solenoid coil were integrated with 64-element cylindrical phased-array ultrasound transducers (rectal/esophageal). METHODS The design of integrated coils took into account the transducer geometry (360° acoustic window within endoluminal space). The rectal coil was sealed on a plastic support and placed reversibly on the transducer head. The esophageal coil was fully embedded within the transducer head, resulting in one indivisible device. Comparison of integrated versus external coils was performed on a clinical 1.5T scanner. RESULTS The integrated coils showed higher sensitivity compared with the standard extracorporeal coil with factors of up to 7.5 (rectal applicator) and 3.3 (esophageal applicator). High-resolution MR images for both anatomy (voxel 0.4 × 0.4 × 5 mm(3)) and thermometry (voxel 0.75 × 0.75 × 8 mm(3), 2 s/image) were acquired in vivo with the rectal endoscopic device. The temperature feedback loop accurately controlled multiple control points over the region of interest. CONCLUSION This study showed significant improvement of MR data quality using endoluminal integrated coils versus standard external coil. Inframillimeter spatial resolution and accurate feedback control of MR-guided HICU thermotherapy were achieved.
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Affiliation(s)
- Mihaela Rata
- INSERM, Therapeutic Applications of Ultrasound, U556 (currently LabTAU - U1032), Université de Lyon, Lyon, F-69003, France.,Université de Lyon, Université Claude Bernard Lyon 1, Lyon, F-69003, France
| | - Vlad Birlea
- INSERM, Therapeutic Applications of Ultrasound, U556 (currently LabTAU - U1032), Université de Lyon, Lyon, F-69003, France.,Babes-Bolyai University, Faculty of Physics, Cluj-Napoca, Romania
| | - Adriana Murillo
- INSERM, Therapeutic Applications of Ultrasound, U556 (currently LabTAU - U1032), Université de Lyon, Lyon, F-69003, France
| | - Christian Paquet
- Université de Lyon, VetAgro Sup, EA 4174, Marcy l'Etoile, F-69280, France
| | - François Cotton
- Université de Lyon, Université Claude Bernard Lyon 1, Lyon, F-69003, France.,MR Unit, Radiology Department, Lyon Sud University Hospital, Hospices Civils de Lyon, Pierre-Bénite, F-69495, France
| | - Rares Salomir
- INSERM, Therapeutic Applications of Ultrasound, U556 (currently LabTAU - U1032), Université de Lyon, Lyon, F-69003, France.,Radiology Department, Faculty of Medicine, University of Geneva, Geneva, CH-1211, Switzerland
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Canney MS, Chavrier F, Tsysar S, Chapelon JY, Lafon C, Carpentier A. A multi-element interstitial ultrasound applicator for the thermal therapy of brain tumors. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2013; 134:1647-1655. [PMID: 23927205 DOI: 10.1121/1.4812883] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Interstitial thermal therapy is a minimally invasive treatment modality that has been used clinically for ablating both primary and secondary brain tumors. Here a multi-element interstitial ultrasound applicator is described that allows for increased spatial control during thermal ablation of tumors as compared to existing clinical devices. The device consists of an array of 56 ultrasound elements operating at 6 MHz, oriented on the seven faces of a 3.2 mm flexible catheter. The device was first characterized using the acoustic holography method to examine the functioning of the array. Then experiments were performed to measure heating in tissue-mimicking gel phantoms and ex vivo tissue samples using magnetic resonance imaging-based thermometry. Experimental measurements were compared with results obtained using numerical simulations. Last, simulations were performed to study the feasibility of using the device for thermal ablation in the brain. Experimental results show that the device can be used to induce a temperature rise of greater than 20 °C in ex vivo tissue samples and numerical simulations further demonstrate that tumors with diameters of greater than 30-mm could potentially be treated.
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Affiliation(s)
- Michael S Canney
- CarThéra, Brain and Spine Institute, Pitié Salpêtrière Hospital, 47-83 Boulevard de l'Hôpital, 75013 Paris, France.
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Vincenot J, Melodelima D, Chavrier F, Vignot A, Chapelon JY. Augmentation du volume traité par ultrasons focalisés de haute intensité pour le traitement des métastases hépatiques. Ing Rech Biomed 2011. [DOI: 10.1016/j.irbm.2011.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Mast TD, Barthe PG, Makin IRS, Slayton MH, Karunakaran CP, Burgess MT, Alqadah A, Rudich SM. Treatment of rabbit liver cancer in vivo using miniaturized image-ablate ultrasound arrays. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:1609-21. [PMID: 21821349 DOI: 10.1016/j.ultrasmedbio.2011.05.850] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 05/03/2011] [Accepted: 05/10/2011] [Indexed: 05/09/2023]
Abstract
In the preclinical studies reported here, VX2 cancer within rabbit liver has been treated by bulk ultrasound ablation employing miniaturized image-ablate arrays. Array probes were constructed with 32 elements in a 2.3 × 20 mm(2) aperture, packaged within a 3.1 mm stainless steel tube with a cooling and coupling balloon for in vivo use. The probes were measured capable of 50% fractional bandwidth for pulse-echo imaging (center frequency 4.4 MHz) with >110 W/cm(2) surface intensity available at sonication frequencies 3.5 and 4.8 MHz. B-scan imaging performance of the arrays was measured to be comparable to larger diagnostic linear arrays, although nearfield image quality was reduced by ringdown artifacts. A series of in vivo ablation procedures was performed using an unfocused 32-element aperture firing at 4.8 MHz with exposure durations 20-70.5 s and in situ spatial average, temporal average intensities 22.4-38.5 W/cm(2). Ablation of a complete tumor cross-section was confirmed by vital staining in seven of 12 exposures, with four exposures ablating an additional margin >1 mm beyond the tumor in all directions. Analysis suggests a threshold ablation effect, with complete ablation of tumor cross-sections for exposures with delivery of >838 J acoustic energy. The results show feasibility for in vivo liver cancer ablation using miniaturized image-ablate arrays suitable for interstitial deployment.
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Affiliation(s)
- T Douglas Mast
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH 45267-0586, USA.
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Gandini A, Melodelima D, Schenone F, N'Djin AW, Chapelon JY, Rivoire M. High-intensity focused ultrasound (HIFU)-assisted hepatic resection in an animal model. Ann Surg Oncol 2011; 19 Suppl 3:S447-54. [PMID: 21796492 DOI: 10.1245/s10434-011-1875-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Indexed: 12/13/2022]
Abstract
BACKGROUND Bleeding is the main cause of postoperative complications of hepatic surgery. To minimize intraoperative bleeding during hepatectomy, resections are generally carried out under hepatic vascular control despite the risk of liver dysfunction in patients with chronic liver disease. This study evaluates the feasibility and safety of high-intensity focused ultrasound (HIFU)-assisted hepatic resection during an open procedure in an animal model. METHODS Three groups of 12-14-week-old Landrace pigs (n = 7/group) were used to evaluate HIFU-assisted liver resection (group A) vs liver resection with or without portal triad clamping (groups B and C). In each pig, liver resection was performed on the right and left paramedian lobes. The following were evaluated and compared in the 3 groups: total blood loss, blood loss/cm(2) of resection area, clip density, procedure duration, morbidity, and mortality. RESULTS Median blood loss was significantly lower in group A than in group B (P = .02), and group C (P = .007). Median blood loss/cm(2) of resection area was 4.77 mL/cm² in group A, 11.35 mL/cm² in group B, 12.22 mL/cm² in Group C. Precoagulation resulted in sealing blood vessels <5 mm; therefore, median clip density during liver transection was 0.78 clip/cm² in group A, 1.61 clip/cm(2) in group B, and 1.57 clip/cm(2) in group C. Median duration of the surgical procedure was 12 min in group A, 21 min in group B, and 19 min in group C. CONCLUSIONS HIFU-assisted hepatic resection during an open procedure in an animal model is safe, reduces bleeding, and allows real-time ultrasound guidance.
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N'Djin WA, Melodelima D, Schenone F, Rivoire M, Chapelon JY. Assisted hepatic resection using a toroidal HIFU device: an in vivo comparative study in pig. Med Phys 2011; 38:1769-78. [PMID: 21626911 DOI: 10.1118/1.3551985] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Bleeding is the main cause of postoperative complications during hepatic surgery. Blood loss and transfusions increase tumor recurrence in liver metastases from colorectal cancer. A high intensity focused ultrasound (HIFU) device with an integrated ultrasound imaging probe was developed for the treatment of colorectal liver metastasis. METHODS The HIFU toroidal-shaped transducer contains 256 elements (working frequency: 3 MHz) and can create a single conical lesion of 7 cm3 in 40 s. Then, the volume of treatment can be significantly increased by juxtaposing single lesions. Presented here is the use of this device in an animal model as a complementary tool to improve surgical resection in the liver. Before transecting the liver, a wall of coagulative necrosis was performed using this device in order to minimize blood loss and dissection time during hepatectomy. Resection assisted by HIFU was compared to classical dissections with clamping [intermittent Pringle maneuver (IPM) group] and without clamping (control group). For each technique, 14 partial liver resections were performed in seven pigs. Blood loss per dissection surface area and resection time were the main outcome parameters. RESULTS Conserving liver blood inflow during hepatic resection assisted by HIFU did not increase total blood loss (7.4 +/- 3.3 ml cm(-2)) compared to hepatic resection performed during IPM and controlled blood inflow (11.2 +/- 2.2 ml cm(-2)). Lower blood loss was measured on average when using HIFU, even though difference with clamping (IPM) was not statistically significant (p = 0.09). Resection assisted by HIFU reduced blood loss by 50% compared to control group (14.0 +/- 3.4 ml cm(-2), p = 0.03). The duration of transection when using HIFU (13 +/- 3 min) was significantly lower compared to clamping (23 +/- 4 min, p < 0.01) and control (18 +/- 3 min, p = 0.02). Precoagulation also resulted in sealing blood vessels with a diameter of less than 5 mm, and therefore the number of clips needed in the HIFU group was significantly lower (0.8 +/- 0.2 cm(-2)) when compared to clamping (1.6 +/- 0.2 cm(-2), p < 0.01) and control (1.8 +/- 0.4 cm(-2), p < 0.01). CONCLUSIONS This method holds promise for future clinical applications in resection of liver metastases.
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Affiliation(s)
- W A N'Djin
- INSERM, Therapeutic Application of Ultrasound, U1032, Lyon F-69003, France
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Kosar A, Sesen M, Oral O, Itah Z, Gozuacik D. Bubbly Cavitating Flow Generation and Investigation of Its Erosional Nature for Biomedical Applications. IEEE Trans Biomed Eng 2011; 58:1337-46. [DOI: 10.1109/tbme.2011.2107322] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Chenot J, Melodelima D, N'djin WA, Souchon R, Rivoire M, Chapelon JY. Intra-operative ultrasound hand-held strain imaging for the visualization of ablations produced in the liver with a toroidal HIFU transducer: first in vivo results. Phys Med Biol 2010; 55:3131-44. [PMID: 20479514 DOI: 10.1088/0031-9155/55/11/010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The use of hand-held ultrasound strain imaging for the intra-operative real-time visualization of HIFU (high-intensity focused ultrasound) ablations produced in the liver by a toroidal transducer was investigated. A linear 12 MHz ultrasound imaging probe was used to obtain radiofrequency signals. Using a fast cross-correlation algorithm, strain images were calculated and displayed at 60 frames s(-1), allowing the use of hand-held strain imaging intra-operatively. Fourteen HIFU lesions were produced in four pigs. Intra-operative strain imaging of HIFU ablations in the liver was feasible owing to the high frame rate. The correlation between dimensions measured on gross pathology and dimensions measured on B-mode images and on strain images were R = 0.72 and R = 0.94 respectively. The contrast between ablated and non-ablated tissue was significantly higher (p < 0.05) in the strain images (22 dB) than in the B-mode images (9 dB). Strain images allowed equivalent or improved definition of ablated regions when compared with B-mode images. Real-time intra-operative hand-held strain imaging seems to be a promising complement to conventional B-mode imaging for the guidance of HIFU ablations produced in the liver during an open procedure. These results support that hand-held strain imaging outperforms conventional B-mode ultrasound and could potentially be used for the assessment of thermal therapies.
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Affiliation(s)
- J Chenot
- Inserm, U556, Lyon, F-69003, France.
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N'Djin WA, Melodelima D, Parmentier H, Rivoire M, Chapelon JY. In vivopreclinical evaluation of the accuracy of toroidal-shaped HIFU treatments using a tumor-mimic model. Phys Med Biol 2010; 55:2137-54. [DOI: 10.1088/0031-9155/55/8/002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Salomir R, Rata M, Cadis D, Petrusca L, Auboiroux V, Cotton F. Endocavitary thermal therapy by MRI-guided phased-array contact ultrasound: experimental and numerical studies on the multi-input single-output PID temperature controller's convergence and stability. Med Phys 2010; 36:4726-41. [PMID: 19928104 DOI: 10.1118/1.3215534] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
PURPOSE Endocavitary high intensity contact ultrasound (HICU) may offer interesting therapeutic potential for fighting localized cancer in esophageal or rectal wall. On-line MR guidance of the thermotherapy permits both excellent targeting of the pathological volume and accurate preoperatory monitoring of the temperature elevation. In this article, the authors address the issue of the automatic temperature control for endocavitary phased-array HICU and propose a tailor-made thermal model for this specific application. The convergence and stability of the feedback loop were investigated against tuning errors in the controller's parameters and against input noise, through ex vivo experimental studies and through numerical simulations in which nonlinear response of tissue was considered as expected in vivo. METHODS An MR-compatible, 64-element, cooled-tip, endorectal cylindrical phased-array applicator of contact ultrasound was integrated with fast MR thermometry to provide automatic feedback control of the temperature evolution. An appropriate phase law was applied per set of eight adjacent transducers to generate a quasiplanar wave, or a slightly convergent one (over the circular dimension). A 2D physical model, compatible with on-line numerical implementation, took into account (1) the ultrasound-mediated energy deposition, (2) the heat diffusion in tissue, and (3) the heat sink effect in the tissue adjacent to the tip-cooling balloon. This linear model was coupled to a PID compensation algorithm to obtain a multi-input single-output static-tuning temperature controller. Either the temperature at one static point in space (situated on the symmetry axis of the beam) or the maximum temperature in a user-defined ROI was tracked according to a predefined target curve. The convergence domain in the space of controller's parameters was experimentally explored ex vivo. The behavior of the static-tuning PID controller was numerically simulated based on a discrete-time iterative solution of the bioheat transfer equation in 3D and considering temperature-dependent ultrasound absorption and blood perfusion. RESULTS The intrinsic accuracy of the implemented controller was approximately 1% in ex vivo trials when providing correct estimates for energy deposition and heat diffusivity. Moreover, the feedback loop demonstrated excellent convergence and stability over a wide range of the controller's parameters, deliberately set to erroneous values. In the extreme case of strong underestimation of the ultrasound energy deposition in tissue, the temperature tracking curve alone, at the initial stage of the MR-controlled HICU treatment, was not a sufficient indicator for a globally stable behavior of the feedback loop. Our simulations predicted that the controller would be able to compensate for tissue perfusion and for temperature-dependent ultrasound absorption, although these effects were not included in the controller's equation. The explicit pattern of acoustic field was not required as input information for the controller, avoiding time-consuming numerical operations. CONCLUSIONS The study demonstrated the potential advantages of PID-based automatic temperature control adapted to phased-array MR-guided HICU therapy. Further studies will address the integration of this ultrasound device with a miniature RF coil for high resolution MRI and, subsequently, the experimental behavior of the controller in vivo.
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Affiliation(s)
- Rares Salomir
- Inserm, U556, Lyon F-69003, France and Université de Lyon, Lyon F-69003, France.
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Characterization Methods of High-Intensity Focused Ultrasound-Induced Thermal Field. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s0065-2717(10)42002-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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20
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Melodelima D, N'Djin WA, Favre-Cabrera J, Parmentier H, Rivoire M, Chapelon JY. Thermal ablation produced using a surgical toroidal high-intensity focused ultrasound device is independent from hepatic inflow occlusion. Phys Med Biol 2009; 54:6353-68. [DOI: 10.1088/0031-9155/54/20/021] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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21
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Melodelima D, N'Djin WA, Parmentier H, Chesnais S, Rivoire M, Chapelon JY. Thermal ablation by high-intensity-focused ultrasound using a toroid transducer increases the coagulated volume. Results of animal experiments. ULTRASOUND IN MEDICINE & BIOLOGY 2009; 35:425-435. [PMID: 19081666 DOI: 10.1016/j.ultrasmedbio.2008.09.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 07/21/2008] [Accepted: 09/19/2008] [Indexed: 05/27/2023]
Abstract
Surgical resection is the only treatment of colorectal liver metastases that can ensure long-term survival and cure in some patients. However, only 20% of patients are suitable for surgery. As a result, many nonresectional modalities of treatment have been assessed to provide an alternative to liver resection. Several limitations have been observed when using these techniques and available evidence is limited. Here, we report that a new design of high intensity focused ultrasound transducer can significantly enlarge the coagulated volume over short periods of time and that treatment in the liver can be guided in real-time using an integrated ultrasound imaging probe. Our long-term objective is to develop a device that can be used during surgery for eventual clinical use in conjunction with resection. Eight ultrasound emitters, divided into 256 elements, were created by sectioning a single toroid piezocomposite transducer. The focal zone was conical in shape and located 70 mm from the transducer; enabling the treatment of deep-seated tumors. A single thermal lesion was created when the eight emitters performed alternative and consecutive 5-s ultrasound exposures. This article presents in vivo evidence that the coagulated volume obtained from a 40 s total exposure in the liver was 7.0 +/- 2.5 cm(3) (minimum 1.5 - maximum 20.0 cm(3)) with an average diameter of 17.5 +/- 3.8 mm (minimum 10.0 - maximum 29.0 mm). All lesions were visible with high contrast on sonograms. The correlation between the diameter of lesions observed on sonograms and during gross examination was 92%. This method also allowed the user to easily enlarge the coagulated volume by juxtaposing single lesions. This approach may have a role in treating unresectable colorectal liver metastases and may also be used in conjunction with resection to extend its limits.
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High-intensity focused ultrasound ablation for the treatment of colorectal liver metastases during an open procedure: study on the pig. Ann Surg 2009; 249:129-36. [PMID: 19106688 DOI: 10.1097/sla.0b013e31818c70b6] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To demonstrate in a porcine model that high-intensity focused ultrasound (HIFU) with toroid-shaped emitters may have a role in treating unresectable colorectal liver metastases. SUMMARY BACKGROUND DATA Surgical resection is the only curative option for colorectal hepatic metastases. Only 20% of patients are suitable for surgery. Many ablative techniques have been assessed but several limitations have been documented: traumatic puncture of the parenchyma, limited size of lesions, and inability to monitor the treatment in real time. METHODS A HIFU device with 256 toroid-shaped emitters and integrated ultrasound imaging probe was used. Single lesions, induced in 40 seconds, and juxtaposition of 6 single lesions were created under ultrasound guidance on 13 pigs. The lesions were studied on sonograms, macroscopically and microscopically up to 30 days after the treatment. RESULTS Ninety percent of the HIFU lesions were immediately hypoechoic on ultrasound imaging. The average coagulated volume obtained from a 40 seconds total exposure in the liver was 7.0 +/- 2.5 cm (1.5-20.0), average diameter: 19.5 +/- 3.8 mm (10.0-29.0). Using the real-time visualization of the treated region, single lesions were easily juxtaposed to produce larger lesions up to 6 cm in diameter without any major complication. CONCLUSIONS This toroid HIFU device allows short treatment times, noninvasiveness regarding the liver and real time ultrasound guidance. It seems to be simpler and more reliable to use than current ablative methods. Additionally, lesions through large vessels (up to 5 mm) being feasible, treatment of some juxta-vascular metastases should be possible.
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N'Djin WA, Melodelima D, Parmentier H, Chesnais S, Rivoire M, Chapelon JY. Utility of a tumor-mimic model for the evaluation of the accuracy of HIFU treatments. results of in vitro experiments in the liver. ULTRASOUND IN MEDICINE & BIOLOGY 2008; 34:1934-1943. [PMID: 18621469 DOI: 10.1016/j.ultrasmedbio.2008.04.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 04/05/2008] [Accepted: 04/24/2008] [Indexed: 05/26/2023]
Abstract
Presented in this article is a tumor-mimic model that allows the evaluation, before clinical trials, of the targeting accuracy of a high intensity focused ultrasound (HIFU) device for the treatment of the liver. The tumor-mimic models are made by injecting a warm solution that polymerizes in hepatic tissue and forms a 1 cm discrete lesion that is detectable by ultrasound imaging and gross pathology. First, the acoustical characteristics of the tumor-mimics model were measured in order to determine if this model could be used as a target for the evaluation of the accuracy of HIFU treatments without modifying HIFU lesions in terms of size, shape and homogeneity. On average (n = 10), the attenuation was 0.39 +/- 0.05 dB.cm(-1) at 1 MHz, the ultrasound propagation velocity was 1523 +/- 1 m.s(-1) and the acoustic impedance was 1.84 +/- 0.00 MRayls. Next, the tumor-mimic models were used in vitro in order to verify, at a preclinical stage, that lesions created by HIFU devices guided by ultrasound imaging are properly positioned in tissues. The HIFU device used in this study is a 256-element phased-array toroid transducer working at a frequency of 3 MHz with an integrated ultrasound imaging probe working at a frequency of 7.5 MHz. An initial series of in vitro experiments has shown that there is no significant difference in the dimensions of the HIFU lesions created in the liver with or without tumor-mimic models (p = 0.3049 and p = 0.8796 for the diameter and depth, respectively). A second in vitro study showed that HIFU treatments performed on five tumor-mimics with safety margins of at least 1 mm were properly positioned. The margins obtained were on average 9.3 +/- 2.7 mm (min. 3.0 - max. 20.0 mm). This article presents in vitro evidence that these tumor-mimics are identifiable by ultrasound imaging, they do not modify the geometry of HIFU lesions and, thus, they constitute a viable model of tumor-mimics indicated for HIFU therapy.
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Kinsey AM, Diederich CJ, Rieke V, Nau WH, Pauly KB, Bouley D, Sommer G. Transurethral ultrasound applicators with dynamic multi-sector control for prostate thermal therapy: in vivo evaluation under MR guidance. Med Phys 2008; 35:2081-93. [PMID: 18561684 DOI: 10.1118/1.2900131] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The purpose of this study was to explore the feasibility and performance of a multi-sectored tubular array transurethral ultrasound applicator for prostate thermal therapy, with potential to provide dynamic angular and length control of heating under MR guidance without mechanical movement of the applicator. Test configurations were fabricated, incorporating a linear array of two multi-sectored tubular transducers (7.8-8.4 MHz, 3 mm OD, 6 mm length), with three 120 degrees independent active sectors per tube. A flexible delivery catheter facilitated water cooling (100 ml min(-1)) within an expandable urethral balloon (35 mm long x 10 mm diameter). An integrated positioning hub allows for rotating and translating the transducer assembly within the urethral balloon for final targeting prior to therapy delivery. Rotational beam plots indicate approximately 90 degrees-100 degrees acoustic output patterns from each 120 degrees transducer sector, negligible coupling between sectors, and acoustic efficiencies between 41% and 53%. Experiments were performed within in vivo canine prostate (n = 3), with real-time MR temperature monitoring in either the axial or coronal planes to facilitate control of the heating profiles and provide thermal dosimetry for performance assessment. Gross inspection of serial sections of treated prostate, exposed to TTC (triphenyl tetrazolium chloride) tissue viability stain, allowed for direct assessment of the extent of thermal coagulation. These devices created large contiguous thermal lesions (defined by 52 degrees C maximum temperature, t43 = 240 min thermal dose contours, and TTC tissue sections) that extended radially from the applicator toward the border of the prostate (approximately15 mm) during a short power application (approximately 8-16 W per active sector, 8-15 min), with approximately 200 degrees or 360 degrees sector coagulation demonstrated depending upon the activation scheme. Analysis of transient temperature profiles indicated progression of lethal temperature and thermal dose contours initially centered on each sector that coalesced within approximately 5 min to produce uniform and contiguous zones of thermal destruction between sectors, with smooth outer boundaries and continued radial propagation in time. The dimension of the coagulation zone along the applicator was well-defined by positioning and active array length. Although not as precise as rotating planar and curvilinear devices currently under development for MR-guided procedures, advantages of these multi-sectored transurethral applicators include a flexible delivery catheter and that mechanical manipulation of the device using rotational motors is not required during therapy. This multi-sectored tubular array transurethral ultrasound technology has demonstrated potential for relatively fast and reasonably conformal targeting of prostate volumes suitable for the minimally invasive treatment of BPH and cancer under MR guidance, with further development warranted.
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Affiliation(s)
- Adam M Kinsey
- Thermal Therapy Research Group, Department of Radiation Oncology, University of California, San Francisco, California 94143, USA
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Treatment of esophageal tumors using high intensity intraluminal ultrasound: first clinical results. J Transl Med 2008; 6:28. [PMID: 18533990 PMCID: PMC2430546 DOI: 10.1186/1479-5876-6-28] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Accepted: 06/05/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Esophageal tumors generally bear a poor prognosis. Radical surgery is generally the only curative method available but is not feasible in the majority of patients; palliative therapy with stent placement is generally performed. It has been demonstrated that High Intensity Ultrasound can induce rapid, complete and well-defined coagulation necrosis. Thus, for the treatment of esophageal tumors, we have designed an ultrasound applicator that uses an intraluminal approach to fill up this therapeutic gap. METHODS Thermal ablation is performed with water-cooled ultrasound transducers operating at a frequency of 10 MHz. Single lesions extend from the transducer surface up to 10 mm in depth when applying an intensity of 14 W/cm2 for 10s. A lumen inside the therapy applicator provides path for an endoscopic ultrasound imaging probe operating at a frequency of 12 MHz. The mechanical rotation of the applicator around its axis enables treatment of sectorial or cylindrical volumes. This method is thus particularly suitable for esophageal tumors that may develop only on a portion of the esophageal circumference. Previous experiments were conducted from bench to in vivo studies on pig esophagi. RESULTS Here we report clinical results obtained on four patients included in a pilot study. The treatment of esophageal tumors was performed under fluoroscopic guidance and ultrasound imaging. Objective tumor response was obtained in all cases and a complete necrosis of a tumor was obtained in one case. All patients recovered uneventfully and dysphagia improved significantly within 15 days, allowing for resuming a solid diet in three cases. CONCLUSION This clinical work demonstrated the efficacy of intraluminal high intensity ultrasound therapy for local tumor destruction in the esophagus.
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Bouchoux G, Lafon C, Berriet R, Chapelon JY, Fleury G, Cathignol D. Dual-mode ultrasound transducer for image-guided interstitial thermal therapy. ULTRASOUND IN MEDICINE & BIOLOGY 2008; 34:607-616. [PMID: 18055099 DOI: 10.1016/j.ultrasmedbio.2007.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 08/29/2007] [Accepted: 09/16/2007] [Indexed: 05/25/2023]
Abstract
Deep-seated tumors can be treated by minimally invasive interstitial ultrasound thermal therapy. A miniature transducer emitting high-intensity acoustic waves is placed in contact with the targeted area to induce local thermal necrosis. Accurate positioning of the probe and treatment monitoring must be achieved for the technique to be effective. A piezocomposite technology was used for obtaining both high-quality imaging and effective treatment with the same transducer. Prototypes were designed and built to be compatible with an endoscopic approach for treating cholangiocarcinomas in the biliary ducts. The transducer had dimensions of 2.5 x 7.5 mm(2), it was cylindrically focused at 10 mm and it was operated at a center frequency of 11 MHz. Transducer efficiency was measured at 71%, and the impulse response corresponded to an axial resolution of 0.2 mm. In-vitro tests were conducted on samples of pig liver in which lesions up to 10 mm in depth were induced. B-mode images were obtained by mechanically rotating the transducer. Treatments were monitored in three ways: (i) classical M-mode images, (ii) images of local deformation of ultrasound lines during heating and (iii) comparison of the displacements induced in the tissue by radiation force, before and after treatments. The successful use of piezocomposite materials to manufacture dual-mode transducers opens new perspectives for interstitial ultrasound thermal therapy.
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Melodelima D, N'Djin WA, Parmentier H, Rivoire M, Chapelon JY. Toric HIFU transducer for large thermal ablation. ACTA ACUST UNITED AC 2008; 2007:230-3. [PMID: 18001931 DOI: 10.1109/iembs.2007.4352265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A new geometry of High Intensity Focused Ultrasound (HIFU) transducer is described to enlarge the coagulated volume and decrease treatments time. Eight transducer elements and their quarter-wave plate were diced out of a single toric piezocomposite element. Each transducer operates at a frequency of 3 MHz. The focal zone is conic and located at 70 mm from the transducer. A 7.5 MHz ultrasound imaging probe is placed in the centre of the device for guiding the treatment. Optimal exposure parameters were determined from numerical simulations. This new geometry allows achieving a thermal ablation of 7.5 cm3 when each of the eight transducers has performed a 5-s ultrasound exposure alternatively and consecutively. In vivo trials have been performed on five pigs to demonstrate this new principle. 33 elementary lesions have been performed. All lesions were reproducible and homogeneous. The average diameter of an elementary lesion obtained in 40 seconds was 19.5 +/- 3.8 mm (min 10 - max 29 mm). The coagulated volume obtained in 40 seconds was on average 9.1 +/- 4.6 cm3 (min 1.5 - max 17.6 cm3).
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Affiliation(s)
- David Melodelima
- French Institute of Health and Medical Research, Lyon, F-69003, France.
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Melodelima D, N'djin W, Parmentier H, Chesnais S, Rivoire M, Chapelon JY. [A tumour-mimic pig liver model for guiding focused ultrasound thermal ablation]. ACTA ACUST UNITED AC 2007; 88:1810-6. [PMID: 18065945 DOI: 10.1016/s0221-0363(07)73960-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
There is no established liver tumour model in pigs to study the efficacy of ablative treatment options available for the treatment of liver tumours by physical agents. A tumour-mimic model visible with high contrast on sonograms and on gross pathology has been studied at mid-term on 20 pigs. The aim was to determine if these tumour-mimics are well tolerated and can be used to validate the use of thermal therapies at a preclinical stage. The dimensions of the tumour-mimics measured on sonograms were reproducible (diameter: 9.6 +/- 1.9 mm) and correlated with those performed in gross pathology (R(2)=0.73). The accuracy of focused ultrasound thermal therapy can be evaluated preclinically using these tumour-mimics.
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Lafon C, Melodelima D, Salomir R, Chapelon JY. Interstitial devices for minimally invasive thermal ablation by high-intensity ultrasound. Int J Hyperthermia 2007; 23:153-63. [PMID: 17578339 DOI: 10.1080/02656730601173029] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Interstitial ultrasound applicators have been proposed for treating deep-seated tumours that cannot be reached with extra-corporeal 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 whose active element is water-cooled and operates at rather high frequency (above 3 MHz) 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 image-guided interstitial thermal ablation. Three major techniques of imaging are used for guiding interstitial treatment: MRI, ultrasound and fluoroscopy. The third section goes in to further detail on diverse described medical applications.
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Affiliation(s)
- C Lafon
- Inserm, U556, Lyon, F-69003 France.
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