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Ahmed B, Reiche CF, Magda JJ, Solzbacher F, Körner J. Smart Hydrogel Swelling State Detection Based on a Power-Transfer Transduction Principle. ACS APPLIED POLYMER MATERIALS 2024; 6:5544-5554. [PMID: 38752016 PMCID: PMC11091848 DOI: 10.1021/acsapm.4c00808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 04/08/2024] [Accepted: 04/16/2024] [Indexed: 05/18/2024]
Abstract
Stimulus-responsive (smart) hydrogels are a promising sensing material for biomedical contexts due to their reversible swelling change in response to target analytes. The design of application-specific sensors that utilize this behavior requires the development of suitable transduction concepts. The presented study investigates a power-transfer-based readout approach that is sensitive to small volumetric changes of the smart hydrogel. The concept employs two thin film polyimide substrates with embedded conductive strip lines, which are shielded from each other except at the tip region, where the smart hydrogel is sandwiched in between. The hydrogel's volume change in response to a target analyte alters the distance and orientation of the thin films, affecting the amount of transferred power between the two transducer parts and, consequently, the measured sensor output voltage. With proper calibration, the output signal can be used to determine the swelling change of the hydrogel and, consequently, to quantify the stimulus. In proof-of-principle experiments with glucose- and pH-sensitive smart hydrogels, high sensitivity to small analyte concentration changes was found along with very good reproducibility and stability. The concept was tested with two exemplary hydrogels, but the transduction principle in general is independent of the specific hydrogel material, as long as it exhibits a stimulus-dependent volume change. The application vision of the presented research is to integrate in situ blood analyte monitoring capabilities into standard (micro)catheters. The developed sensor is designed to fit into a catheter without obstructing its normal use and, therefore, offers great potential for providing a universally applicable transducer platform for smart catheter-based sensing.
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Affiliation(s)
- Benozir Ahmed
- Department
of Electrical & Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Christopher F. Reiche
- Department
of Electrical & Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Jules J. Magda
- Department
of Chemical Engineering, University of Utah, Salt Lake City, Utah 84112, United States
| | - Florian Solzbacher
- Department
of Electrical & Computer Engineering, University of Utah, Salt Lake
City, Utah 84112, United States
| | - Julia Körner
- Faculty
of
Electrical Engineering & Computer Science, Leibniz Universität Hannover, 30167 Hannover, Germany
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2
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Gupta P, Heffter T, Zubair M, Hsu IC, Burdette EC, Diederich CJ. Treatment Planning Strategies for Interstitial Ultrasound Ablation of Prostate Cancer. IEEE OPEN JOURNAL OF ENGINEERING IN MEDICINE AND BIOLOGY 2024; 5:362-375. [PMID: 38899026 PMCID: PMC11186654 DOI: 10.1109/ojemb.2024.3397965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 03/28/2024] [Accepted: 05/03/2024] [Indexed: 06/21/2024] Open
Abstract
PURPOSE To develop patient-specific 3D models using Finite-Difference Time-Domain (FDTD) simulations and pre-treatment planning tools for the selective thermal ablation of prostate cancer with interstitial ultrasound. This involves the integration with a FDA 510(k) cleared catheter-based ultrasound interstitial applicators and delivery system. METHODS A 3D generalized "prostate" model was developed to generate temperature and thermal dose profiles for different applicator operating parameters and anticipated perfusion ranges. A priori planning, based upon these pre-calculated lethal thermal dose and iso-temperature clouds, was devised for iterative device selection and positioning. Full 3D patient-specific anatomic modeling of actual placement of single or multiple applicators to conformally ablate target regions can be applied, with optional integrated pilot-point temperature-based feedback control and urethral/rectum cooling. These numerical models were verified against previously reported ex-vivo experimental results obtained in soft tissues. RESULTS For generic prostate tissue, 360 treatment schemes were simulated based on the number of transducers (1-4), applied power (8-20 W/cm2), heating time (5, 7.5, 10 min), and blood perfusion (0, 2.5, 5 kg/m3/s) using forward treatment modelling. Selectable ablation zones ranged from 0.8-3.0 cm and 0.8-5.3 cm in radial and axial directions, respectively. 3D patient-specific thermal treatment modeling for 12 Cases of T2/T3 prostate disease demonstrate applicability of workflow and technique for focal, quadrant and hemi-gland ablation. A temperature threshold (e.g., Tthres = 52 °C) at the treatment margin, emulating placement of invasive temperature sensing, can be applied for pilot-point feedback control to improve conformality of thermal ablation. Also, binary power control (e.g., Treg = 45 °C) can be applied which will regulate the applied power level to maintain the surrounding temperature to a safe limit or maximum threshold until the set heating time. CONCLUSIONS Prostate-specific simulations of interstitial ultrasound applicators were used to generate a library of thermal-dose distributions to visually optimize and set applicator positioning and directivity during a priori treatment planning pre-procedure. Anatomic 3D forward treatment planning in patient-specific models, along with optional temperature-based feedback control, demonstrated single and multi-applicator implant strategies to effectively ablate focal disease while affording protection of normal tissues.
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Affiliation(s)
- Pragya Gupta
- Department of Radiation OncologyUniversity of California San FranciscoSan FranciscoCA94115USA
| | | | - Muhammad Zubair
- Department of Neurology and Neurological SciencesStanford UniversityStanfordCA94305USA
| | - I-Chow Hsu
- Department of Radiation OncologyUniversity of California San FranciscoSan FranciscoCA94115USA
| | | | - Chris J. Diederich
- Department of Radiation OncologyUniversity of California San FranciscoSan FranciscoCA94115USA
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3
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Kappel AD, Jha R, Guggilapu S, Smith WJ, Feroze AH, Dmytriw AA, Vicenty-Padilla J, Alcedo Guardia RE, Gessler FA, Patel NJ, Du R, See AP, Peruzzi PP, Aziz-Sultan MA, Bernstock JD. Endovascular Applications for the Management of High-Grade Gliomas in the Modern Era. Cancers (Basel) 2024; 16:1594. [PMID: 38672676 PMCID: PMC11049132 DOI: 10.3390/cancers16081594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Revised: 04/10/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
High-grade gliomas (HGGs) have a poor prognosis and are difficult to treat. This review examines the evolving landscape of endovascular therapies for HGGs. Recent advances in endovascular catheter technology and delivery methods allow for super-selective intra-arterial cerebral infusion (SSIACI) with increasing precision. This treatment modality may offer the ability to deliver anti-tumoral therapies directly to tumor regions while minimizing systemic toxicity. However, challenges persist, including blood-brain barrier (BBB) penetration, hemodynamic complexities, and drug-tumor residence time. Innovative adjunct techniques, such as focused ultrasound (FUS) and hyperosmotic disruption, may facilitate BBB disruption and enhance drug penetration. However, hemodynamic factors that limit drug residence time remain a limitation. Expanding therapeutic options beyond chemotherapy, including radiotherapy and immunobiologics, may motivate future investigations. While preclinical and clinical studies demonstrate moderate efficacy, larger randomized trials are needed to validate the clinical benefits. Additionally, future directions may involve endovascular sampling for peri-tumoral surveillance; changes in drug formulations to prolong residence time; and the exploration of non-pharmaceutical therapies, like radioembolization and photodynamic therapy. Endovascular strategies hold immense potential in reshaping HGG treatment paradigms, offering targeted and minimally invasive approaches. However, overcoming technical challenges and validating clinical efficacy remain paramount for translating these advancements into clinical care.
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Affiliation(s)
- Ari D. Kappel
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Rohan Jha
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
| | - Saibaba Guggilapu
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
| | - William J. Smith
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Abdullah H. Feroze
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Adam A. Dmytriw
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Juan Vicenty-Padilla
- Neurosurgery Section, School of Medicine University of Puerto Rico, Medical Sciences Campus, San Juan P.O. Box 365067, Puerto Rico (R.E.A.G.)
| | - Rodolfo E. Alcedo Guardia
- Neurosurgery Section, School of Medicine University of Puerto Rico, Medical Sciences Campus, San Juan P.O. Box 365067, Puerto Rico (R.E.A.G.)
| | - Florian A. Gessler
- Department of Neurosurgery, Rostock University Hospital, 18057 Rostock, Germany
| | - Nirav J. Patel
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Rose Du
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Alfred P. See
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Pier Paolo Peruzzi
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Mohammad A. Aziz-Sultan
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Joshua D. Bernstock
- Harvard Medical School, Boston, MA 02115, USA; (A.D.K.); (S.G.); (R.D.); (A.P.S.)
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA
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4
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Cooley MB, Wegierak D, Exner AA. Using imaging modalities to predict nanoparticle distribution and treatment efficacy in solid tumors: The growing role of ultrasound. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2024; 16:e1957. [PMID: 38558290 PMCID: PMC11006412 DOI: 10.1002/wnan.1957] [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: 04/26/2023] [Revised: 12/22/2023] [Accepted: 02/27/2024] [Indexed: 04/04/2024]
Abstract
Nanomedicine in oncology has not had the success in clinical impact that was anticipated in the early stages of the field's development. Ideally, nanomedicines selectively accumulate in tumor tissue and reduce systemic side effects compared to traditional chemotherapeutics. However, this has been more successful in preclinical animal models than in humans. The causes of this failure to translate may be related to the intra- and inter-patient heterogeneity of the tumor microenvironment. Predicting whether a patient will respond positively to treatment prior to its initiation, through evaluation of characteristics like nanoparticle extravasation and retention potential in the tumor, may be a way to improve nanomedicine success rate. While there are many potential strategies to accomplish this, prediction and patient stratification via noninvasive medical imaging may be the most efficient and specific strategy. There have been some preclinical and clinical advances in this area using MRI, CT, PET, and other modalities. An alternative approach that has not been studied as extensively is biomedical ultrasound, including techniques such as multiparametric contrast-enhanced ultrasound (mpCEUS), doppler, elastography, and super-resolution processing. Ultrasound is safe, inexpensive, noninvasive, and capable of imaging the entire tumor with high temporal and spatial resolution. In this work, we summarize the in vivo imaging tools that have been used to predict nanoparticle distribution and treatment efficacy in oncology. We emphasize ultrasound imaging and the recent developments in the field concerning CEUS. The successful implementation of an imaging strategy for prediction of nanoparticle accumulation in tumors could lead to increased clinical translation of nanomedicines, and subsequently, improved patient outcomes. This article is categorized under: Diagnostic Tools In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery Emerging Technologies.
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Affiliation(s)
- Michaela B Cooley
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA
| | - Dana Wegierak
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA
| | - Agata A Exner
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA
- Department of Radiology, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, Ohio, USA
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5
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Huang W, Ning C, Zhang R, Xu J, Chen B, Li Z, Cui Y, Shao W. Evaluation of the dual-frequency transducer for controlling thermal ablation morphology using frequency shift keying signal. Int J Hyperthermia 2022; 39:1344-1357. [PMID: 36223887 DOI: 10.1080/02656736.2022.2130999] [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: 10/17/2022] Open
Abstract
PURPOSE The catheter-based ultrasound (CBUS) can reach the target tissue directly and achieve rapid treatment. The frequency shift keying (FSK) signal is proposed to regulate and evaluate tumor ablation by a miniaturized dual-frequency transducer. METHODS A dual-frequency transducer prototype (3 × 7 × 0.4 mm) was designed and fabricated for the CBUS applicator (OD: 3.8 mm) based on the fundamental frequency of 5.21 MHz and the third harmonic frequency of 16.88 MHz. Then, the acoustic fields and temperature field distributions using the FSK signals (with 0, 25, 50, 75, and 100% third harmonic frequency duty ratios) were simulated by finite element analysis. Finally, tissue ablation and temperature monitoring were performed in phantom and ex vivo tissue, respectively. RESULTS At the same input electrical power (20 W), the output acoustic power of the fundamental frequency of the transducer was 10.03 W (electroacoustic efficiencies: 50.1%), and that of the third harmonic frequency was 6.19 W (30.6%). As the third harmonic frequency duty ratios increased, the shape of thermal lesions varied from strip to droplet in simulated and phantom experimental results. The same trend was observed in ex vivo tests. CONCLUSION Dual-frequency transducers excited by the FSK signal can control the morphology of lesions. SIGNIFICANCE The acoustic power deposition of CBUS was optimized to achieve precise ablation.
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Affiliation(s)
- Wenchang Huang
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Suzhou, Jiangsu, China.,Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Chuanlong Ning
- College of Mechanical and Electrical Engineering, Hohai University, Changzhou, Jiangsu, China
| | - Rui Zhang
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Suzhou, Jiangsu, China.,Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Jie Xu
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Beiyi Chen
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Suzhou, Jiangsu, China.,Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Zhangjian Li
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Yaoyao Cui
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Weiwei Shao
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu, China
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Baig MS, Haque MA, Konatham TKR, Mohammad BD, Yahya BA, Saffiruddin SS, Siddiqui FA, Khan SL. Recent advancements on hyperthermia driven controlled drug delivery from nanotherapeutics. RECENT ADVANCES IN DRUG DELIVERY AND FORMULATION 2022; 16:RADDF-EPUB-126101. [PMID: 36056855 DOI: 10.2174/2667387816666220902091043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 04/27/2022] [Accepted: 05/01/2022] [Indexed: 06/15/2023]
Abstract
Previous reviews of the works on magnetic nanoparticles for hyperthermia induced treatment concentrated mostly on magnetic fluid hyperthermia (MFH) employing monometallic/metal oxide nanocomposites. In the literature, the word "hyperthermia" was also limited to the use of heat for medicinal purposes. A number of publications have recently been published demonstrating that magnetic nanoparticle-based hyperthermia may produce restricted high temperatures, resulting in the release of medicines that are either connected to the magnetic nanoparticles or encased in polymer matrices. In this debate, we propose broadening the concept of "hyperthermia" to encompass temperature-based treatment as well as magnetically controlled medication delivery. The review also addresses core-shell magnetic nanomaterials, particularly nanoshells made by stacked assembly, for the use of hyperthermia-based treatment and precise administration of drugs. The primary objective of this review article is to demonstrate how the combination of hyperthermia-induced therapy and 'on demand' drug release models may lead to effective applications in personalized medicine.
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Affiliation(s)
- Mirza Shahed Baig
- Y. B. Chavan College of Pharmacy, Aurangabad, Maharashtra, India-431001
| | - M Akiful Haque
- Department of Pharmaceutical Analysis, School of Pharmacy, Anurag University, Ghatkesar, Hyderabad, India-500088
| | - Teja Kumar Reddy Konatham
- Department of Pharmaceutical Analysis, School of Pharmacy, Anurag University, Ghatkesar, Hyderabad, India-500088
| | - Badrud Duza Mohammad
- G. R. T. Institute of Pharmaceutical Education and Research, GRT Mahalakshmi Nagar, Tiruttani, Tamil Nadu, India-631209
| | | | | | - Falak A Siddiqui
- MUP\'s College of Pharmacy (B Pharm), Degaon, Risod, Washim, Maharashtra, India-444504
| | - Sharuk L Khan
- MUP\'s College of Pharmacy (B Pharm), Degaon, Risod, Washim, Maharashtra, India-444504
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7
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Pfannenstiel A, Iannuccilli J, Cornelis FH, Dupuy DE, Beard WL, Prakash P. Shaping the future of microwave tumor ablation: a new direction in precision and control of device performance. Int J Hyperthermia 2022; 39:664-674. [DOI: 10.1080/02656736.2021.1991012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Austin Pfannenstiel
- Precision Microwave Inc, Manhattan, KS, USA
- Department of Electrical and Computer Engineering, Kansas State University, Manhattan, KS, USA
| | - Jason Iannuccilli
- Department of Diagnostic Imaging, Division of Interventional Oncology, Rhode Island Hospital, Providence, RI, USA
| | - Francois H. Cornelis
- Interventional Radiology Service, Memorial Sloan Kettering Cancer Center, NY, USA
| | - Damian E. Dupuy
- Diagnostic Imaging, Brown University, Radiology, Cape Cod Hospital, MA, USA
| | - Warren L. Beard
- Department of Clinical Sciences, Kansas State University, Manhattan, KS, USA
| | - Punit Prakash
- Department of Electrical and Computer Engineering, Kansas State University, Manhattan, KS, USA
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8
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Yang C, Wu Y, Nie M, Wang Q, Liu Y. Highly Stretchable and Conductive Carbon Fiber/Polyurethane Conductive Films Featuring Interlocking Interfaces. ACS APPLIED MATERIALS & INTERFACES 2021; 13:38656-38665. [PMID: 34346227 DOI: 10.1021/acsami.1c08266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Stretchable conductors are essential assembly units of next-generation flexible electronics, requiring excellent conductivity and stretchability simultaneously. However, poor interfacial adhesion between conductive fillers and polymer matrixes often triggers the relative slippage and dislocation of the conductive network, deteriorating the final conductivity. Herein, we constructed interlocking interfaces in a polyurethane (PU) conductive composite by introducing brush-like carbon fibers (CFs) with laterally grown zinc oxide nanowires (ZnO NWs). The ZnO NW-enabled construction of the functional interfaces integrated the CFs tightly with the polymer matrix to greatly improve the interfacial adhesion and suppress the sliding displacement of conductive fillers upon external load, contributing to excellent mechanical strength and conductive stability. Specifically, the combination of high mechanical strength (7.19 MPa) and stable conductivity (26.3 S/m under 100% strain, approaching 30 S/m of the initial conductivity) was demonstrated for the brush-like CF/PU film. Finally, the application potential of the novel stretchable conductor as a thermal therapy unit and connecting wire in a flexible circuit was explored successfully under complex dynamic deformations. Accordingly, this inspiring result creatively combines the interface geometry with conductive stability, and offers a facile and effective route to prepare excellent stretchable conductors, which can be easily applied to other conductive composites.
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Affiliation(s)
- Changhua Yang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Yanan Wu
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Min Nie
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Qi Wang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Yuansen Liu
- Technology Innovation Center for Exploitation of Marine Biological Resources, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China
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9
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Karunakaran CP, Burgess MT, Rao MB, Holland CK, Mast TD. Effect of Overpressure on Acoustic Emissions and Treated Tissue Histology in ex Vivo Bulk Ultrasound Ablation. ULTRASOUND IN MEDICINE & BIOLOGY 2021; 47:2360-2376. [PMID: 34023187 PMCID: PMC8243850 DOI: 10.1016/j.ultrasmedbio.2021.04.006] [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: 06/30/2020] [Revised: 04/08/2021] [Accepted: 04/11/2021] [Indexed: 06/12/2023]
Abstract
Bulk ultrasound ablation is a thermal therapy approach in which tissue is heated by unfocused or weakly focused sonication (average intensities on the order of 100 W/cm2) to achieve coagulative necrosis within a few minutes exposure time. Assessing the role of bubble activity, including acoustic cavitation and tissue vaporization, in bulk ultrasound ablation may help in making bulk ultrasound ablation safer and more effective for clinical applications. Here, two series of ex vivo ablation trials were conducted to investigate the role of bubble activity and tissue vaporization in bulk ultrasound ablation. Fresh bovine liver tissue was ablated with unfocused, continuous-wave ultrasound using ultrasound image-ablate arrays sonicating at 31 W/cm2 (0.9 MPa amplitude) for either 20 min at a frequency of 3.1 MHz or 10 min at 4.8 MHz. Tissue specimens were maintained at a static overpressure of either 0.52 or 1.2 MPa to suppress bubble activity and tissue vaporization or at atmospheric pressure for control groups. A passive cavitation detector was used to record subharmonic (1.55 or 2.4 MHz), broadband (1.2-1.5 MHz) and low-frequency (5-20 kHz) acoustic emissions. Treated tissue was stained with 2% triphenyl tetrazolium chloride to evaluate thermal lesion dimensions. Subharmonic emissions were significantly reduced in overpressure groups compared with control groups. Correlations observed between acoustic emissions and lesion dimensions were significant and positive for the 3.1-MHz series, but significant and negative for the 4.8-MHz series. The results indicate that for bulk ultrasound ablation, where both acoustic cavitation and tissue vaporization are possible, bubble activity can enhance ablation in the absence of tissue vaporization, but can reduce thermal lesion dimensions in the presence of vaporization.
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Affiliation(s)
| | - Mark T Burgess
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA
| | - Marepalli B Rao
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA; Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio, USA
| | - Christy K Holland
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA; Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, Ohio, USA
| | - T Douglas Mast
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA; Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, Ohio, USA.
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10
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Kok HP, Cressman ENK, Ceelen W, Brace CL, Ivkov R, Grüll H, Ter Haar G, Wust P, Crezee J. Heating technology for malignant tumors: a review. Int J Hyperthermia 2021; 37:711-741. [PMID: 32579419 DOI: 10.1080/02656736.2020.1779357] [Citation(s) in RCA: 139] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The therapeutic application of heat is very effective in cancer treatment. Both hyperthermia, i.e., heating to 39-45 °C to induce sensitization to radiotherapy and chemotherapy, and thermal ablation, where temperatures beyond 50 °C destroy tumor cells directly are frequently applied in the clinic. Achievement of an effective treatment requires high quality heating equipment, precise thermal dosimetry, and adequate quality assurance. Several types of devices, antennas and heating or power delivery systems have been proposed and developed in recent decades. These vary considerably in technique, heating depth, ability to focus, and in the size of the heating focus. Clinically used heating techniques involve electromagnetic and ultrasonic heating, hyperthermic perfusion and conductive heating. Depending on clinical objectives and available technology, thermal therapies can be subdivided into three broad categories: local, locoregional, or whole body heating. Clinically used local heating techniques include interstitial hyperthermia and ablation, high intensity focused ultrasound (HIFU), scanned focused ultrasound (SFUS), electroporation, nanoparticle heating, intraluminal heating and superficial heating. Locoregional heating techniques include phased array systems, capacitive systems and isolated perfusion. Whole body techniques focus on prevention of heat loss supplemented with energy deposition in the body, e.g., by infrared radiation. This review presents an overview of clinical hyperthermia and ablation devices used for local, locoregional, and whole body therapy. Proven and experimental clinical applications of thermal ablation and hyperthermia are listed. Methods for temperature measurement and the role of treatment planning to control treatments are discussed briefly, as well as future perspectives for heating technology for the treatment of tumors.
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Affiliation(s)
- H Petra Kok
- Department of Radiation Oncology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Erik N K Cressman
- Department of Interventional Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Wim Ceelen
- Department of GI Surgery, Ghent University Hospital, Ghent, Belgium
| | - Christopher L Brace
- Department of Radiology and Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Robert Ivkov
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Mechanical Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA.,Department of Materials Science and Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Holger Grüll
- Department of Diagnostic and Interventional Radiology, Faculty of Medicine, University Hospital of Cologne, University of Cologne, Cologne, Germany
| | - Gail Ter Haar
- Department of Physics, The Institute of Cancer Research, London, UK
| | - Peter Wust
- Department of Radiation Oncology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Johannes Crezee
- Department of Radiation Oncology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
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11
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Wang D, Adams MS, Jones PD, Liu D, Burdette EC, Diederich CJ. High contrast ultrasonic method with multi-spatiotemporal compounding for monitoring catheter-based ultrasound thermal therapy: Development and Ex Vivo Evaluations. IEEE Trans Biomed Eng 2021; 68:3131-3141. [PMID: 33755552 DOI: 10.1109/tbme.2021.3067910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Changes in ultrasound backscatter energy (CBE) imaging can monitor thermal therapy. Catheter-based ultrasound (CBUS) can treat deep tumors with precise spatial control of energy deposition and ablation zones, of which CBE estimation can be limited by low contrast and robustness due to small or inconsistent changes in ultrasound data. This study develops a multi-spatiotemporal compounding CBE (MST-CBE) imaging approach for monitoring specific to CBUS thermal therapy. METHODS Ex vivo thermal ablations were performed with stereotactic positioning of a 180 directional CBUS applicator, temperature monitoring probes, endorectal US probe, and subsequent lesion sectioning and measurement. Five frames of raw radiofrequency data were acquired throughout in 15s intervals. Using window-by-window estimation methods, absolute and positive components of MST-CBE images at each point were obtained by the compounding ratio of squared envelope data within an increasing spatial size in each short-time window. RESULTS Compared with conventional US, Nakagami, and CBE imaging, the detection contrast and robustness quantified by tissue-modification-ratio improved by 37.24.7 (p<0.001), 37.55.2 (p<0.001), and 6.44.0 dB (p<0.05) in the MST-CBE imaging, respectively. Correlation coefficient and bias between cross-sectional dimensions of the ablation zones measured in tissue sections and estimated from MST-CBE were up to 0.91 (p<0.001) and -0.02 mm2, respectively. CONCLUSION The MST-CBE approach can monitor the detailed changes within target tissues and effectively characterize the dimensions of the ablation zone during CBUS energy deposition. SIGNIFICANCE The MST-CBE approach could be practical for improved accuracy and contrast of monitoring and evaluation for CBUS thermal therapy.
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Nazer B, Giraud D, Zhao Y, Hodovan J, Elman MR, Masri A, Gerstenfeld EP, Lindner JR. High-intensity ultrasound catheter ablation achieves deep mid-myocardial lesions in vivo. Heart Rhythm 2020; 18:623-631. [PMID: 33385570 DOI: 10.1016/j.hrthm.2020.12.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/17/2020] [Accepted: 12/23/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND Radiofrequency ablation of epicardial and mid-myocardial ventricular arrhythmias is limited by lesion depth. OBJECTIVE The purpose of this study was to generate deep mid-interventricular septal (IVS) lesions using high-intensity ultrasound (US) from an endocardial catheter-based approach. METHODS Irrigated US catheters (12 F) were fabricated with 3 × 5 mm transducers of 5.0, 6.5, and 8.0 MHz frequencies and compared in an ex vivo perfused myocardial ablation model. In vivo septal ablation in swine (n = 12) was performed via femoral venous access to the right ventricle. Lesions were characterized by echocardiography, cardiac magnetic resonance imaging, and electroanatomic voltage mapping pre- and post-ablation, and at 30 days. Four animals were euthanized immediately post-ablation to compare acute and chronic lesion histology and gross pathology. RESULTS In ex vivo models, maximal lesion depth and volume was achieved by 6.5 MHz catheters, which were used in vivo. Lesion depth by gross pathology was similar post-ablation (10.8 mm; 95% confidence interval [CI] 9.9-12.4 mm) and at 30 days (11.2 mm; 95% CI 10.6-12.4 mm) (P = .56). Lesion volume decreased post-ablation to 30 days (from 255 [95% CI 198-440] to 162 [95% CI 133-234] mm3; P = .05), yet transmurality increased from 58% (95% CI 50%-76%) to 81% (95% CI 74%-93%), attributable to a reduction in IVS thickness (from 16.0 ± 1.7 to 10.6 ± 2.4 mm; P = .007). Magnetic resonance imaging confirmed dense septal ablation by delayed enhancement, with increased T1 time post-ablation and at 30 days and increased T2 time only post-ablation. Voltage mapping of both sides of IVS demonstrated reduced unipolar (but not bipolar) voltage along the IVS. CONCLUSION High-intensity US catheter ablation may be an effective treatment of mid-myocardial or epicardial ventricular arrhythmias from an endocardial approach.
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Affiliation(s)
- Babak Nazer
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon.
| | - David Giraud
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon
| | - Yan Zhao
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon
| | - James Hodovan
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon
| | - Miriam R Elman
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon; School of Public Health, OHSU/Portland State University, Portland, Oregon
| | - Ahmad Masri
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon
| | - Edward P Gerstenfeld
- Division of Cardiology, University of California San Francisco, San Francisco, California
| | - Jonathan R Lindner
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon
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Daunizeau L, Nguyen A, Le Garrec M, Chapelon JY, N'Djin WA. Robot-assisted ultrasound navigation platform for 3D HIFU treatment planning: Initial evaluation for conformal interstitial ablation. Comput Biol Med 2020; 124:103941. [PMID: 32818742 DOI: 10.1016/j.compbiomed.2020.103941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/19/2020] [Accepted: 07/27/2020] [Indexed: 10/23/2022]
Abstract
Interstitial Ultrasound-guided High Intensity Focused Ultrasound (USgHIFU) therapy has the potential to deliver ablative treatments which conform to the target tumor. In this study, a robot-assisted US-navigation platform has been developed for 3D US guidance and planning of conformal HIFU ablations. The platform was used to evaluate a conformal therapeutic strategy associated with an interstitial dual-mode USgHIFU catheter prototype (64 elements linear-array, measured central frequency f = 6.5 MHz), developed for the treatment of HepatoCellular Carcinoma (HCC). The platform included a 3D navigation environment communicating in real-time with an open research dual-mode US scanner/HIFU generator and a robotic arm, on which the USgHIFU catheter was mounted. 3D US-navigation was evaluated in vitro for guiding and planning conformal HIFU ablations using a tumor-mimic model in porcine liver. Tumor-mimic volumes were then used as targets for evaluating conformal HIFU treatment planning in simulation. Height tumor-mimics (ovoid- or disc-shaped, sizes: 3-29 cm3) were created and visualized in liver using interstitial 2D US imaging. Robot-assisted spatial manipulation of these images and real-time 3D navigation allowed reconstructions of 3D B-mode US images for accurate tumor-mimic volume estimation (relative error: 4 ± 5%). Sectorial and full-revolution HIFU scanning (angular sectors: 88-360°) could both result in conformal ablations of the tumor volumes, as soon as their radii remained ≤ 24 mm. The presented US navigation-guided HIFU procedure demonstrated advantages for developing conformal interstitial therapies in standard operative rooms. Moreover, the modularity of the developed platform makes it potentially useful for developing other HIFU approaches.
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Affiliation(s)
- L Daunizeau
- LabTAU, INSERM, Centre Léon Bérard, Université Lyon 1, Univ Lyon, F-69003, Lyon, France.
| | - A Nguyen
- LabTAU, INSERM, Centre Léon Bérard, Université Lyon 1, Univ Lyon, F-69003, Lyon, France
| | - M Le Garrec
- LabTAU, INSERM, Centre Léon Bérard, Université Lyon 1, Univ Lyon, F-69003, Lyon, France
| | - J Y Chapelon
- LabTAU, INSERM, Centre Léon Bérard, Université Lyon 1, Univ Lyon, F-69003, Lyon, France
| | - W A N'Djin
- LabTAU, INSERM, Centre Léon Bérard, Université Lyon 1, Univ Lyon, F-69003, Lyon, France
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Liu D, Adams M, Burdette EC, Diederich CJ. Dual-sectored transurethral ultrasound for thermal treatment of stress urinary incontinence: in silico studies in 3D anatomical models. Med Biol Eng Comput 2020; 58:1325-1340. [PMID: 32277340 DOI: 10.1007/s11517-020-02152-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 02/25/2020] [Indexed: 11/24/2022]
Abstract
The purpose of this study is to investigate the feasibility and performance of a stationary, non-focused dual-sectored tubular transurethral ultrasound applicator for thermal exposure of tissue regions adjacent to the urethra for treatment of stress urinary incontinence (SUI) through acoustic and biothermal simulations on 3D anatomical models. Parametric studies in a generalized tissue model over dual-sectored ultrasound applicator configurations (acoustic surface intensities, lateral active acoustic output sector angles, and durations) were performed. Selected configurations and delivery strategies were applied on 3D pelvic anatomical models. Temperature and thermal dose distributions on the target region and surrounding tissues were calculated. Endovaginal cooling was explored as a strategy to mitigate vaginal heating. The 75-90° dual-sectored transurethral tubular transducer (3.5 mm outer diameter (OD), 14 mm length, 6.5 MHz, 8.8-10.2 W/cm2) and 2-3-min sonication duration were selected from the parametric study for acoustic and biothermal simulations on anatomical models. The transurethral applicator with two opposing 75-90° active lateral tubular sectors can create two heated volumes for a total of up to 1.8 cm3 over 60 EM43 °C, with at least 10 mm radial penetration depth, 1.2 mm urethral sparing, and no lethal damage to the vagina and adjacent bone (< 60 EM43 °C). Endovaginal cooling can be applied to further reduce the vaginal wall exposure (< 15 EM43 °C). Simulations on 3D anatomical models indicate that dual-sectored transurethral ultrasound applicators can selectively heat pelvic floor tissue lateral to the mid-urethra in short treatment durations, without damaging adjacent vaginal and bone tissues, as a potential alternative treatment option for stress urinary incontinence. Graphical abstract Schema for in silico investigation of transurethral ultrasound thermal therapy applicator for minimally invasive treatment of SUI.
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Affiliation(s)
- Dong Liu
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Matthew Adams
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
| | | | - Chris J Diederich
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA.
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Seynhaeve A, Amin M, Haemmerich D, van Rhoon G, ten Hagen T. Hyperthermia and smart drug delivery systems for solid tumor therapy. Adv Drug Deliv Rev 2020; 163-164:125-144. [PMID: 32092379 DOI: 10.1016/j.addr.2020.02.004] [Citation(s) in RCA: 107] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 02/13/2020] [Accepted: 02/19/2020] [Indexed: 12/31/2022]
Abstract
Chemotherapy is a cornerstone of cancer therapy. Irrespective of the administered drug, it is crucial that adequate drug amounts reach all cancer cells. To achieve this, drugs first need to be absorbed, then enter the blood circulation, diffuse into the tumor interstitial space and finally reach the tumor cells. Next to chemoresistance, one of the most important factors for effective chemotherapy is adequate tumor drug uptake and penetration. Unfortunately, most chemotherapeutic agents do not have favorable properties. These compounds are cleared rapidly, distribute throughout all tissues in the body, with only low tumor drug uptake that is heterogeneously distributed within the tumor. Moreover, the typical microenvironment of solid cancers provides additional hurdles for drug delivery, such as heterogeneous vascular density and perfusion, high interstitial fluid pressure, and abundant stroma. The hope was that nanotechnology will solve most, if not all, of these drug delivery barriers. However, in spite of advances and decades of nanoparticle development, results are unsatisfactory. One promising recent development are nanoparticles which can be steered, and release content triggered by internal or external signals. Here we discuss these so-called smart drug delivery systems in cancer therapy with emphasis on mild hyperthermia as a trigger signal for drug delivery.
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Izadifar Z, Izadifar Z, Chapman D, Babyn P. An Introduction to High Intensity Focused Ultrasound: Systematic Review on Principles, Devices, and Clinical Applications. J Clin Med 2020; 9:jcm9020460. [PMID: 32046072 PMCID: PMC7073974 DOI: 10.3390/jcm9020460] [Citation(s) in RCA: 155] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 01/29/2020] [Accepted: 02/01/2020] [Indexed: 12/22/2022] Open
Abstract
Ultrasound can penetrate deep into tissues and interact with human tissue via thermal and mechanical mechanisms. The ability to focus an ultrasound beam and its energy onto millimeter-size targets was a significant milestone in the development of therapeutic applications of focused ultrasound. Focused ultrasound can be used as a non-invasive thermal ablation technique for tumor treatment and is being developed as an option to standard oncologic therapies. High-intensity focused ultrasound has now been used for clinical treatment of a variety of solid malignant tumors, including those in the pancreas, liver, kidney, bone, prostate, and breast, as well as uterine fibroids and soft-tissue sarcomas. Magnetic resonance imaging and Ultrasound imaging can be combined with high intensity focused ultrasound to provide real-time imaging during ablation. Magnetic resonance guided focused ultrasound represents a novel non-invasive method of treatment that may play an important role as an alternative to open neurosurgical procedures for treatment of a number of brain disorders. This paper briefly reviews the underlying principles of HIFU and presents current applications, outcomes, and complications after treatment. Recent applications of Focused ultrasound for tumor treatment, drug delivery, vessel occlusion, histotripsy, movement disorders, and vascular, oncologic, and psychiatric applications are reviewed, along with clinical challenges and potential future clinical applications of HIFU.
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Affiliation(s)
- Zahra Izadifar
- Division of Biomedical Engineering, College of Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada
- Correspondence: ; Tel.: +1-306-966-7827; Fax: +1-306-966-4651
| | - Zohreh Izadifar
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Dean Chapman
- Anatomy & Cell Biology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Paul Babyn
- Department of Medical Imaging, Royal University Hospital, Saskatoon, SK S7N 0W8, Canada
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Liu D, Adams MS, Diederich CJ. Endobronchial high-intensity ultrasound for thermal therapy of pulmonary malignancies: simulations with patient-specific lung models. Int J Hyperthermia 2019; 36:1108-1121. [PMID: 31726895 DOI: 10.1080/02656736.2019.1683234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Objective: This study investigates the feasibility of endobronchial ultrasound applicators for thermal ablation of lung tumors using acoustic and biothermal simulations.Methods: Endobronchial ultrasound applicators with planar (10 mm width) or tubular transducers (6 mm outer diameter (OD)) encapsulated by expandable coupling balloons (10 mm OD) are considered for treating tumors from within major airways; smaller catheter-based applicators with tubular transducers (1.7-4 mm OD) and coupling balloons (2.5-5 mm OD) are considered within deep lung airways. Parametric studies were applied to evaluate transducer configurations, tumor size and location, effects of acoustic reflection and absorption at tumor-lung parenchyma interfaces, and the utility of lung flooding for enhancing accessibility. Patient-specific anatomical lung models, with various geometries and locations of tumors, were developed for further evaluation of device performance and treatment strategies. Temperature and thermal dose distributions were calculated and reported.Results: Large endobronchial applicators with planar or tubular transducers (3-7 MHz, 5 min) can thermally ablate tumors attached to major bronchi at up to 3 cm depth, where reflection and attenuation of normal lung localize tumor heating; with lung flooding, endobronchial applicators can ablate ∼2 cm diameter tumors with up to ∼2 cm separation from the bronchial wall, without significant heating of intervening tissue. Smaller catheter-based tubular applicators can ablate tumors up to 2-3 cm in diameter from deep lung airways (5-9 MHz, 5 min).Conclusion: Simulations demonstrate the feasibility of endobronchial ultrasound applicators to deliver thermal coagulation of 2-3 cm diameter tumors adjacent to or accessible from major and deep lung airways.
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Affiliation(s)
- Dong Liu
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Matthew S Adams
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Chris J Diederich
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
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18
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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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Almekkawy M, Chen J, Ellis MD, Haemmerich D, Holmes DR, Linte CA, Panescu D, Pearce J, Prakash P, Zderic V. Therapeutic Systems and Technologies: State-of-the-Art Applications, Opportunities, and Challenges. IEEE Rev Biomed Eng 2019; 13:325-339. [PMID: 30951478 PMCID: PMC7341980 DOI: 10.1109/rbme.2019.2908940] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this review, we present current state-of-the-art developments and challenges in the areas of thermal therapy, ultrasound tomography, image-guided therapies, ocular drug delivery, and robotic devices in neurorehabilitation. Additionally, intellectual property and regulatory aspects pertaining to therapeutic systems and technologies are addressed.
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Dobšíček Trefná H, Schmidt M, van Rhoon GC, Kok HP, Gordeyev SS, Lamprecht U, Marder D, Nadobny J, Ghadjar P, Abdel-Rahman S, Kukiełka AM, Strnad V, Hurwitz MD, Vujaskovic Z, Diederich CJ, Stauffer PR, Crezee J. Quality assurance guidelines for interstitial hyperthermia. Int J Hyperthermia 2019; 36:277-294. [PMID: 30676101 DOI: 10.1080/02656736.2018.1564155] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Quality assurance (QA) guidelines are essential to provide uniform execution of clinical hyperthermia treatments and trials. This document outlines the clinical and technical consequences of the specific properties of interstitial heat delivery and specifies recommendations for hyperthermia administration with interstitial techniques. Interstitial hyperthermia aims at tumor temperatures in the 40-44 °C range as an adjunct to radiation or chemotherapy. The clinical part of this document imparts specific clinical experience of interstitial heat delivery to various tumor sites as well as recommended interstitial hyperthermia workflow and procedures. The second part describes technical requirements for quality assurance of current interstitial heating equipment including electromagnetic (radiative and capacitive) and ultrasound heating techniques. Detailed instructions are provided on characterization and documentation of the performance of interstitial hyperthermia applicators to achieve reproducible hyperthermia treatments of uniform high quality. Output power and consequent temperature rise are the key parameters for characterization of applicator performance in these QA guidelines. These characteristics determine the specific maximum tumor size and depth that can be heated adequately. The guidelines were developed by the ESHO Technical Committee with participation of senior STM members and members of the Atzelsberg Circle.
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Affiliation(s)
- H Dobšíček Trefná
- a Department of Electrical Engineering , Chalmers University of Technology , Göteborg , Sweden
| | - M Schmidt
- b Department of Radiation Oncology , University Hospital Erlangen , Erlangen , Germany
| | - G C van Rhoon
- c Department of Radiation Oncology , Erasmus MC Cancer Institute , Rotterdam , the Netherlands
| | - H P Kok
- d Department of Radiation Oncology, Cancer Center Amsterdam , Amsterdam UMC, University of Amsterdam , Amsterdam , the Netherlands
| | - S S Gordeyev
- e Department of Colorectal Oncology , N.N.Blokhin Russian Cancer Research Center , Moscow, Russia
| | - U Lamprecht
- f Radioonkologische Klinik , Universitätsklinikum Tübingen , Tübingen , Germany
| | - D Marder
- g Kantonsspital Aarau , Radio-Onkologie-Zentrum KSA-KSB , Aarau , Switzerland
| | - J Nadobny
- h Klinik für Radioonkologie und Strahlentherapie , Charité Universitätsmedizin Berlin , Berlin , Germany
| | - P Ghadjar
- h Klinik für Radioonkologie und Strahlentherapie , Charité Universitätsmedizin Berlin , Berlin , Germany
| | - S Abdel-Rahman
- i Klinikum der Universität München-Campus Grosshadern , München , Germany
| | - A M Kukiełka
- j Department of Radiation Oncology , Centrum Diagnostyki i Terapii Onkologicznej Nu-Med , Zamość , Poland
| | - V Strnad
- b Department of Radiation Oncology , University Hospital Erlangen , Erlangen , Germany
| | - M D Hurwitz
- k Department of Radiation Oncology , Thomas Jefferson University , Philadelphia , PA , USA
| | - Z Vujaskovic
- l Department of Radiation Oncology , University of Maryland Baltimore , Baltimore , MD , USA
| | - C J Diederich
- m Department of Radiation Oncology , University of California , San Francisco , CA , USA
| | - P R Stauffer
- k Department of Radiation Oncology , Thomas Jefferson University , Philadelphia , PA , USA
| | - J Crezee
- d Department of Radiation Oncology, Cancer Center Amsterdam , Amsterdam UMC, University of Amsterdam , Amsterdam , the Netherlands
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Adams MS, Salgaonkar VA, Scott SJ, Sommer G, Diederich CJ. Integration of deployable fluid lenses and reflectors with endoluminal therapeutic ultrasound applicators: Preliminary investigations of enhanced penetration depth and focal gain. Med Phys 2017; 44:5339-5356. [PMID: 28681404 DOI: 10.1002/mp.12458] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 06/19/2017] [Accepted: 07/02/2017] [Indexed: 02/06/2023] Open
Abstract
PURPOSE Catheter-based ultrasound applicators can generate thermal ablation of tissues adjacent to body lumens, but have limited focusing and penetration capabilities due to the small profile of integrated transducers required for the applicator to traverse anatomical passages. This study investigates a design for an endoluminal or laparoscopic ultrasound applicator with deployable acoustic reflector and fluid lens components, which can be expanded after device delivery to increase the effective acoustic aperture and allow for deeper and dynamically adjustable target depths. Acoustic and biothermal theoretical studies, along with benchtop proof-of-concept measurements, were performed to investigate the proposed design. METHODS The design schema consists of an array of tubular transducer(s) situated at the end of a catheter assembly, surrounded by an expandable water-filled conical balloon with a secondary reflective compartment that redirects acoustic energy distally through a plano-convex fluid lens. By controlling the lens fluid volume, the convex surface can be altered to adjust the focal length or collapsed for device insertion or removal. Acoustic output of the expanded applicator assembly was modeled using the rectangular radiator method and secondary sources, accounting for reflection and refraction at interfaces. Parametric studies of transducer radius (1-5 mm), height (3-25 mm), frequency (1.5-3 MHz), expanded balloon diameter (10-50 mm), lens focal length (10-100 mm), lens fluid (silicone oil, perfluorocarbon), and tissue attenuation (0-10 Np/m/MHz) on beam distributions and focal gain were performed. A proof-of-concept applicator assembly was fabricated and characterized using hydrophone-based intensity profile measurements. Biothermal simulations of endoluminal ablation in liver and pancreatic tissue were performed for target depths between 2 and 10 cm. RESULTS Simulations indicate that focal gain and penetration depth scale with the expanded reflector-lens balloon diameter, with greater achievable performance using perfluorocarbon lens fluid. Simulations of a 50 mm balloon OD, 10 mm transducer outer diameter (OD), 1.5 MHz assembly in water resulted in maximum intensity gain of ~170 (focal dimensions: ~12 mm length × 1.4 mm width) at ~5 cm focal depth and focal gains above 100 between 24 and 84 mm depths. A smaller (10 mm balloon OD, 4 mm transducer OD, 1.5 MHz) configuration produced a maximum gain of 6 at 9 mm depth. Compared to a conventional applicator with a fixed spherically focused transducer of 12 mm diameter, focal gain was enhanced at depths beyond 20 mm for assembly configurations with balloon diameters ≥ 20 mm. Hydrophone characterizations of the experimental assembly (31 mm reflector/lens diameter, 4.75 mm transducer radius, 1.7 MHz) illustrated focusing at variable depths between 10-70 mm with a maximum gain of ~60 and demonstrated agreement with theoretical simulations. Biothermal simulations (30 s sonication, 75 °C maximum) indicate that investigated applicator assembly configurations, at 30 mm and 50 mm balloon diameters, could create localized ellipsoidal thermal lesions increasing in size from 10 to 55 mm length × 3-6 mm width in liver tissue as target depth increased from 2 to 10 cm. CONCLUSIONS Preliminary theoretical and experimental analysis demonstrates that combining endoluminal ultrasound with an expandable acoustic reflector and fluid lens assembly can significantly enhance acoustic focal gain and penetration from inherently smaller diameter catheter-based applicators.
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Affiliation(s)
- Matthew S Adams
- Thermal Therapy Research Group, University of California San Francisco, 2340 Sutter Street, S341, San Francisco, CA, 94115, USA.,University of California, Berkeley - University of California, San Francisco Graduate Program in Bioengineering, University of California, CA, USA
| | - Vasant A Salgaonkar
- Thermal Therapy Research Group, University of California San Francisco, 2340 Sutter Street, S341, San Francisco, CA, 94115, USA
| | - Serena J Scott
- Thermal Therapy Research Group, University of California San Francisco, 2340 Sutter Street, S341, San Francisco, CA, 94115, USA
| | - Graham Sommer
- Department of Radiology, Stanford University, Stanford, CA, 94305, USA
| | - Chris J Diederich
- Thermal Therapy Research Group, University of California San Francisco, 2340 Sutter Street, S341, San Francisco, CA, 94115, USA.,University of California, Berkeley - University of California, San Francisco Graduate Program in Bioengineering, University of California, CA, USA
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Scott SJ, Adams MS, Salgaonkar V, Sommer FG, Diederich CJ. Theoretical investigation of transgastric and intraductal approaches for ultrasound-based thermal therapy of the pancreas. J Ther Ultrasound 2017; 5:10. [PMID: 28469915 PMCID: PMC5414307 DOI: 10.1186/s40349-017-0090-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 02/07/2017] [Indexed: 02/07/2023] Open
Abstract
Background The goal of this study was to theoretically investigate the feasibility of intraductal and transgastric approaches to ultrasound-based thermal therapy of pancreatic tumors, and to evaluate possible treatment strategies. Methods This study considered ultrasound applicators with 1.2 mm outer diameter tubular transducers, which are inserted into the tissue to be treated by an endoscopic approach, either via insertion through the gastric wall (transgastric) or within the pancreatic duct lumen (intraductal). 8 patient-specific, 3D, transient, biothermal and acoustic finite element models were generated to model hyperthermia (n = 2) and ablation (n = 6), using sectored (210°–270°, n = 4) and 360° (n = 4) transducers for treatment of 3.3–17.0 cm3 tumors in the head (n = 5), body (n = 2), and tail (n = 1) of the pancreas. A parametric study was performed to determine appropriate treatment parameters as a function of tissue attenuation, blood perfusion rates, and distance to sensitive anatomy. Results Parametric studies indicated that pancreatic tumors up to 2.5 or 2.7 cm diameter can be ablated within 10 min with the transgastric and intraductal approaches, respectively. Patient-specific simulations demonstrated that 67.1–83.3% of the volumes of four sample 3.3–11.4 cm3 tumors could be ablated within 3–10 min using transgastric or intraductal approaches. 55.3–60.0% of the volume of a large 17.0 cm3 tumor could be ablated using multiple applicator positions within 20–30 min with either transgastric or intraductal approaches. 89.9–94.7% of the volume of two 4.4–11.4 cm3 tumors could be treated with intraductal hyperthermia. Sectored applicators are effective in directing acoustic output away from and preserving sensitive structures. When acoustic energy is directed towards sensitive structures, applicators should be placed at least 13.9–14.8 mm from major vessels like the aorta, 9.4–12.0 mm from other vessels, depending on the vessel size and flow rate, and 14 mm from the duodenum. Conclusions This study demonstrated the feasibility of generating shaped or conformal ablative or hyperthermic temperature distributions within pancreatic tumors using transgastric or intraductal ultrasound.
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Affiliation(s)
- Serena J Scott
- Department of Radiation Oncology, Thermal Therapy Research Group, University of California, San Francisco, 1600 Divisadero Street, Suite H1031, San Francisco, CA 94143-1708 USA
| | - Matthew S Adams
- Department of Radiation Oncology, Thermal Therapy Research Group, University of California, San Francisco, 1600 Divisadero Street, Suite H1031, San Francisco, CA 94143-1708 USA.,UC Berkeley - UC San Francisco Graduate Program in Bioengineering, California, USA
| | - Vasant Salgaonkar
- Department of Radiation Oncology, Thermal Therapy Research Group, University of California, San Francisco, 1600 Divisadero Street, Suite H1031, San Francisco, CA 94143-1708 USA
| | - F Graham Sommer
- Department of Radiology, Stanford University School of Medicine, Stanford, CA USA
| | - Chris J Diederich
- Department of Radiation Oncology, Thermal Therapy Research Group, University of California, San Francisco, 1600 Divisadero Street, Suite H1031, San Francisco, CA 94143-1708 USA.,UC Berkeley - UC San Francisco Graduate Program in Bioengineering, California, USA
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Adams MS, Salgaonkar VA, Plata-Camargo J, Jones PD, Pascal-Tenorio A, Chen HY, Bouley DM, Sommer G, Pauly KB, Diederich CJ. Endoluminal ultrasound applicators for MR-guided thermal ablation of pancreatic tumors: Preliminary design and evaluation in a porcine pancreas model. Med Phys 2017; 43:4184. [PMID: 27370138 DOI: 10.1118/1.4953632] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PURPOSE Endoluminal ultrasound may serve as a minimally invasive option for delivering thermal ablation to pancreatic tumors adjacent to the stomach or duodenum. The objective of this study was to explore the basic feasibility of this treatment strategy through the design, characterization, and evaluation of proof-of-concept endoluminal ultrasound applicators capable of placement in the gastrointestinal (GI) lumen for volumetric pancreas ablation under MR guidance. METHODS Two variants of the endoluminal applicator, each containing a distinct array of two independently powered transducers (10 × 10 mm 3.2 MHz planar; or 8 × 10 × 20 mm radius of curvature 3.3 MHz curvilinear geometries) at the distal end of a meter long flexible catheter assembly, were designed and fabricated. Transducers and circulatory water flow for acoustic coupling and luminal cooling were contained by a low-profile polyester balloon covering the transducer assembly fixture. Each applicator incorporated miniature spiral MR coils and mechanical features (guiding tips and hinges) to facilitate tracking and insertion through the GI tract under MRI guidance. Acoustic characterization of each device was performed using radiation force balance and hydrophone measurements. Device delivery into the upper GI tract, adjacent to the pancreas, and heating characteristics for treatment of pancreatic tissue were evaluated in MR-guided ex vivo and in vivo porcine experiments. MR guidance was utilized for anatomical target identification, tracking/positioning of the applicator, and MR temperature imaging (MRTI) for PRF-based multislice thermometry, implemented in the real-time RTHawk software environment. RESULTS Force balance and hydrophone measurements indicated efficiencies of 48.8% and 47.8% and -3 dB intensity beam-widths of 3.2 and 1.2 mm for the planar and curvilinear transducers, respectively. Ex vivo studies on whole-porcine carcasses revealed capabilities of producing ablative temperature rise (ΔT > 15 °C) contours in pancreatic tissue 4-40 mm long and 4-28 mm wide for the planar transducer applicator (1-13 min sonication duration, ∼4 W/cm(2) applied acoustic intensity). Curvilinear transducers produced more selective heating, with a narrower ΔT > 15 °C contour length and width of up to 1-24 mm and 2-7 mm, respectively (1-7 min sonication duration, ∼4 W/cm(2) applied acoustic intensity). Active tracking of the miniature spiral coils was achieved using a Hadamard encoding tracking sequence, enabling real-time determination of each coil's coordinates and automated prescription of imaging planes for thermometry. In vivo MRTI-guided heating trials in three pigs demonstrated capability of ∼20 °C temperature elevation in pancreatic tissue at 2 cm depths from the applicator, with 5-7 W/cm(2) applied intensity and 6-16 min sonication duration. Dimensions of thermal lesions in the pancreas ranged from 12 to 28 mm, 3 to 10 mm, and 5 to 10 mm in length, width, and depth, respectively, as verified through histological analysis of tissue sections. Multiple-baseline reconstruction and respiratory-gated acquisition were demonstrated to be effective strategies in suppressing motion artifacts for clear evolution of temperature profiles during MRTI in the in vivo studies. CONCLUSIONS This study demonstrates the technical feasibility of generating volumetric ablation in pancreatic tissue using endoluminal ultrasound applicators positioned in the stomach lumen. MR guidance facilitates target identification, device tracking/positioning, and treatment monitoring through real-time multislice PRF-based thermometry.
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Affiliation(s)
- Matthew S Adams
- Thermal Therapy Research Group, University of California, San Francisco, 2340 Sutter Street, S341, San Francisco, California 94115 and The UC Berkeley - UCSF Graduate Program in Bioengineering, University of California, Berkeley, and University of California, San Francisco, California 94115
| | - Vasant A Salgaonkar
- Thermal Therapy Research Group, University of California, San Francisco, 2340 Sutter Street, S341, San Francisco, California 94115
| | - Juan Plata-Camargo
- Department of Radiology, Stanford University, Stanford, California 94305
| | - Peter D Jones
- Thermal Therapy Research Group, University of California, San Francisco, 2340 Sutter Street, S341, San Francisco, California 94115
| | - Aurea Pascal-Tenorio
- Department of Comparative Medicine, Stanford University, Stanford, California 94305
| | - Hsin-Yu Chen
- The UC Berkeley - UCSF Graduate Program in Bioengineering, University of California, Berkeley, and University of California, San Francisco, California 94115
| | - Donna M Bouley
- Department of Comparative Medicine, Stanford University, Stanford, California 94305
| | - Graham Sommer
- Department of Radiology, Stanford University, Stanford, California 94305
| | - Kim Butts Pauly
- Department of Radiology, Stanford University, Stanford, California 94305
| | - Chris J Diederich
- Thermal Therapy Research Group, University of California, San Francisco, 2340 Sutter Street, S341, San Francisco, California 94115 and The UC Berkeley - UCSF Graduate Program in Bioengineering, University of California, Berkeley, and University of California, San Francisco, California 94115
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Sebek J, Curto S, Bortel R, Prakash P. Analysis of minimally invasive directional antennas for microwave tissue ablation. Int J Hyperthermia 2016; 33:51-60. [DOI: 10.1080/02656736.2016.1195519] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- Jan Sebek
- Department of Electrical and Computer Engineering, Kansas State University, Manhattan, Kansas, USA
- Department of Circuit Theory, Czech Technical University, Prague, Czech Republic
| | - Sergio Curto
- Department of Electrical and Computer Engineering, Kansas State University, Manhattan, Kansas, USA
| | - Radoslav Bortel
- Department of Circuit Theory, Czech Technical University, Prague, Czech Republic
| | - Punit Prakash
- Department of Electrical and Computer Engineering, Kansas State University, Manhattan, Kansas, USA
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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: 17] [Impact Index Per Article: 2.1] [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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Affiliation(s)
- Gail ter Haar
- Joint Physics department, The Institute of Cancer Research , Sutton , London, UK
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