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Cheng PC, Lo WC, Chang CM, Wen MH, Liao LJ. A Training Course for Simulating Head and Neck Ultrasound-Guided Procedures Using a Gelatin Phantom Model. Ann Otol Rhinol Laryngol 2024:34894241262113. [PMID: 38898810 DOI: 10.1177/00034894241262113] [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: 06/21/2024]
Abstract
OBJECTIVES Ultrasound (US)-guided procedures can be used in the evaluation and treatment of neck masses. However, these procedures need to be practiced before being executed on humans. The aim of this study is to evaluate the efficacy of a training program using a gelatin phantom to practice US-guided procedures. METHODS This program included a lecture and practice with a gelatin phantom. We recruited doctors from different hospitals to practice US-guided procedures, including fine-needle aspiration (FNA), core needle biopsy (CNB), percutaneous ethanol injection (PEI), and radiofrequency ablation (RFA). We used a questionnaire with a 5-point scale to evaluate the effectiveness of practicing US-guided procedures under a gelatin phantom. RESULTS Forty-four doctors participated, and 37 of them completed the questionnaires. After training, the mean (SD) scores of the doctors were 4.68 (0.47) for "Satisfaction with this course," 4.54 (0.61) for "Ease in practicing FNA&CNB using the phantom," 4.49 (0.61) for "Ease in practicing PEI using the phantom," 4.49 (0.65) for "Ease in practicing RFA using the phantom," and 4.57 (0.55) for "The course effectively familiarizing participants with US-guided procedures." Participants without experience in US examination had higher scores than those with previous US experience, but the difference was not statistically significant. CONCLUSION A combination of lectures and hands-on practice of US-guided procedures using a gelatin phantom is an effective educational method for doctors interested in head and neck US. After the training program, doctors gained a better understanding of the necessary steps and skills required for these procedures. They can correctly insert the instruments into the target lesion and perform different US-guided procedures.
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Affiliation(s)
- Ping-Chia Cheng
- Department of Otolaryngology Head and Neck Surgery, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Head and Neck Cancer Surveillance and Research Study Group, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Department of Communication Engineering, Asia Eastern University of Science and Technology, New Taipei City, Taiwan
| | - Wu-Chia Lo
- Department of Otolaryngology Head and Neck Surgery, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Head and Neck Cancer Surveillance and Research Study Group, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Graduate Institute of Medicine, Yuan Ze University, Taoyuan, Taiwan
| | - Chih-Ming Chang
- Department of Otolaryngology Head and Neck Surgery, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Ming-Hsun Wen
- Department of Otolaryngology Head and Neck Surgery, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Li-Jen Liao
- Department of Otolaryngology Head and Neck Surgery, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Head and Neck Cancer Surveillance and Research Study Group, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Department of Electrical Engineering, Yuan Ze University, Taoyuan, Taiwan
- Medical Engineering Office, Far Eastern Memorial Hospital, New Taipei City, Taiwan
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Fernandez SV, Kim J, Sadat D, Marcus C, Suh E, Mclntosh R, Shah A, Dagdeviren C. A Dynamic Ultrasound Phantom with Tissue-Mimicking Mechanical and Acoustic Properties. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2400271. [PMID: 38647427 PMCID: PMC11165531 DOI: 10.1002/advs.202400271] [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: 01/08/2024] [Revised: 03/25/2024] [Indexed: 04/25/2024]
Abstract
Tissue-mimicking phantoms are valuable tools that aid in improving the equipment and training available to medical professionals. However, current phantoms possess limited utility due to their inability to precisely simulate multiple physical properties simultaneously, which is crucial for achieving a system understanding of dynamic human tissues. In this work, novel materials design and fabrication processes to produce various tissue-mimicking materials (TMMs) for skin, adipose, muscle, and soft tissue at a human scale are developed. Target properties (Young's modulus, density, speed of sound, and acoustic attenuation) are first defined for each TMM based on literature. Each TMM recipe is developed, associated mechanical and acoustic properties are characterized, and the TMMs are confirmed to have comparable mechanical and acoustic properties with the corresponding human tissues. Furthermore, a novel sacrificial core to fabricate a hollow, ellipsoid-shaped bladder phantom complete with inlet and outlet tubes, which allow liquids to flow through and expand this phantom, is adopted. This dynamic bladder phantom with realistic mechanical and acoustic properties to human tissues in combination with the developed skin, soft tissue, and subcutaneous adipose tissue TMMs, culminates in a human scale torso tank and electro-mechanical system that can be systematically utilized for characterizing various medical imaging devices.
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Affiliation(s)
- Sara V. Fernandez
- Media LabMassachusetts Institute of TechnologyCambridgeMA02139USA
- Department of Materials Science and EngineeringMassachusetts Institute of TechnologyCambridgeMA02139USA
| | - Jin‐Hoon Kim
- Media LabMassachusetts Institute of TechnologyCambridgeMA02139USA
| | - David Sadat
- Media LabMassachusetts Institute of TechnologyCambridgeMA02139USA
| | - Colin Marcus
- Media LabMassachusetts Institute of TechnologyCambridgeMA02139USA
- Department of Electrical Engineering and Computer ScienceMassachusetts Institute of TechnologyCambridgeMA02139USA
| | - Emma Suh
- Media LabMassachusetts Institute of TechnologyCambridgeMA02139USA
- Department of Mechanical EngineeringMassachusetts Institute of TechnologyCambridgeMA02139USA
| | - Rachel Mclntosh
- Media LabMassachusetts Institute of TechnologyCambridgeMA02139USA
- Department of Electrical Engineering and Computer ScienceMassachusetts Institute of TechnologyCambridgeMA02139USA
| | - Aastha Shah
- Media LabMassachusetts Institute of TechnologyCambridgeMA02139USA
| | - Canan Dagdeviren
- Media LabMassachusetts Institute of TechnologyCambridgeMA02139USA
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Badawe HM, Raad P, Khraiche ML. High-resolution acoustic mapping of tunable gelatin-based phantoms for ultrasound tissue characterization. Front Bioeng Biotechnol 2024; 12:1276143. [PMID: 38456002 PMCID: PMC10917893 DOI: 10.3389/fbioe.2024.1276143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 02/06/2024] [Indexed: 03/09/2024] Open
Abstract
Background: The choice of gelatin as the phantom material is underpinned by several key advantages it offers over other materials in the context of ultrasonic applications. Gelatin exhibits spatial and temporal uniformity, which is essential in creating reliable tissue-mimicking phantoms. Its stability ensures that the phantom's properties remain consistent over time, while its flexibility allows for customization to match the acoustic characteristics of specific tissues, in addition to its low levels of ultrasound scattering. These attributes collectively make gelatin a preferred choice for fabricating phantoms in ultrasound-related research. Methods: We developed gelatin-based phantoms with adjustable parameters and conducted high-resolution measurements of ultrasound wave attenuation when interacting with the gelatin phantoms. We utilized a motorized acoustic system designed for 3D acoustic mapping. Mechanical evaluation of phantom elasticity was performed using unconfined compression tests. We particularly examined how varying gelatin concentration influenced ultrasound maximal intensity and subsequent acoustic attenuation across the acoustic profile. To validate our findings, we conducted computational simulations to compare our data with predicted acoustic outcomes. Results: Our results demonstrated high-resolution mapping of ultrasound waves in both gelatin-based phantoms and plain fluid environments. Following an increase in the gelatin concentration, the maximum intensity dropped by 30% and 48% with the 5 MHz and 1 MHz frequencies respectively, while the attenuation coefficient increased, with 67% more attenuation at the 1 MHz frequency recorded at the highest concentration. The size of the focal areas increased systematically as a function of increasing applied voltage and duty cycle yet decreased as a function of increased ultrasonic frequency. Simulation results verified the experimental results with less than 10% deviation. Conclusion: We developed gelatin-based ultrasound phantoms as a reliable and reproducible tool for examining the acoustic and mechanical attenuations taking place as a function of increased tissue elasticity and stiffness. Our experimental measurements and simulations gave insight into the potential use of such phantoms for mimicking soft tissue properties.
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Affiliation(s)
| | | | - Massoud L. Khraiche
- Neural Engineering and Nanobiosensors Group, Biomedical Engineering Program, Maroun Semaan Faculty of Engineering and Architecture, American University of Beirut, Beirut, Lebanon
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Hariyanto AP, Budiarti NT, Suprijanto, Ng KH, Haryanto F, Endarko. Evaluation of physical properties and image of polyvinyl chloride as breast tissue equivalence for dual-modality (mammography and ultrasound). Phys Eng Sci Med 2023; 46:1175-1185. [PMID: 37253939 DOI: 10.1007/s13246-023-01283-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 05/18/2023] [Indexed: 06/01/2023]
Abstract
TMP is gradually becoming a fundamental element for quality assurance and control in ionizing and non-ionizing radiation imaging modalities as well as in the development of different techniques. This study aimed to evaluate and obtain polyvinyl chloride tissue mimicking material for dual-modality breast phantoms in mammography and ultrasound. Breast tissue equivalence was evaluated based on X-ray attenuation properties, speed of sound, attenuation, and acoustic impedance. There are six samples of PVC-plasticizer material with variations of PVC concentration and additives. The evaluation of X-ray attenuation was carried out using mammography from 23 to 35 kV, while the acoustic properties were assessed with mode A ultrasound and a transducer frequency of 5 MHz. A breast phantom was created from TMP material with tissue equivalence and was then evaluated using mammography as well as ultrasound to analyze its image quality. The results showed that samples A (PVC 5%, DOP 95%), B (PVC 7%, DOP 93%), C (PVC 10%, DOP 90%), E (PVC 7%, DOP 90%, graphite 3%), and F (PVC 7%, DOP 90%, silicone oil 3%) have the closest equivalent to the ACR breast phantom material with a different range of 0.01-1.39 in the 23-35 kV range. Based on the evaluation of the acoustic properties of ultrasound, A had high similarity to fat tissue with a difference of 0.03 (dB cm- 1 MHz- 1) and 0.07 (106 kg m- 2 s- 1), while B was close to the glandular tissue with a difference of 9.2 m s- 1. Multilayer breast phantom images' results showed gray levels in mammography and ultrasound modalities. Therefore, this study succeeded in establishing TMP material for mammography and ultrasound. It can also be used for simple quality assurance and control programs.
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Affiliation(s)
- Aditya Prayugo Hariyanto
- Department of Physics, Institut Teknologi Sepuluh Nopember, Kampus ITS - Sukolilo Surabaya 60111, East Java, Indonesia
| | - Nurhanifa Tri Budiarti
- Medical Physicist of Radiology Installation, Gambiran General Hospital, Kediri, East Java, 64133, Indonesia
| | - Suprijanto
- Instrumentation and Control Research Group, Faculty of Industrial Technology, Institut Teknologi Bandung, Jl. Ganesha 10, Labtek VI, 40132, Bandung, Indonesia
| | - Kwan Hoong Ng
- Department of Biomedical Imaging, Faculty of Medicine, Universiti Malaya, 50603, Kuala Lumpur, Malaysia
| | - Freddy Haryanto
- Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10, 40116, Bandung, Indonesia
| | - Endarko
- Department of Physics, Institut Teknologi Sepuluh Nopember, Kampus ITS - Sukolilo Surabaya 60111, East Java, Indonesia.
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Heat transfer capacity in millimeter size breast cancer cells analysis through thermal imaging and FDNCNN for primary stage identification. Biomed Signal Process Control 2023. [DOI: 10.1016/j.bspc.2022.104361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Antoniou A, Georgiou L, Christodoulou T, Panayiotou N, Ioannides C, Zamboglou N, Damianou C. MR relaxation times of agar-based tissue-mimicking phantoms. J Appl Clin Med Phys 2022; 23:e13533. [PMID: 35415875 PMCID: PMC9121050 DOI: 10.1002/acm2.13533] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 12/29/2021] [Indexed: 12/31/2022] Open
Abstract
Agar gels were previously proven capable of accurately replicating the acoustical and thermal properties of real tissue and widely used for the construction of tissue-mimicking phantoms (TMPs) for focused ultrasound (FUS) applications. Given the current popularity of magnetic resonance-guided FUS (MRgFUS), we have investigated the MR relaxation times T1 and T2 of different mixtures of agar-based phantoms. Nine TMPs were constructed containing agar as the gelling agent and various concentrations of silicon dioxide and evaporated milk. An agar-based phantom doped with wood powder was also evaluated. A series of MR images were acquired in a 1.5 T scanner for T1 and T2 mapping. T2 was predominantly affected by varying agar concentrations. A trend toward decreasing T1 with an increasing concentration of evaporated milk was observed. The addition of silicon dioxide decreased both relaxation times of pure agar gels. The proposed phantoms have great potential for use with the continuously emerging MRgFUS technology. The MR relaxation times of several body tissues can be mimicked by adjusting the concentration of ingredients, thus enabling more accurate and realistic MRgFUS studies.
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Affiliation(s)
- Anastasia Antoniou
- Department of Electrical Engineering, Computer Engineering, and Informatics, Cyprus University of Technology, Limassol, Cyprus
| | - Leonidas Georgiou
- Department of Interventional Radiology, German Oncology Center, Limassol, Cyprus
| | | | - Natalie Panayiotou
- Department of Interventional Radiology, German Oncology Center, Limassol, Cyprus
| | - Cleanthis Ioannides
- Department of Interventional Radiology, German Oncology Center, Limassol, Cyprus
| | - Nikolaos Zamboglou
- Department of Interventional Radiology, German Oncology Center, Limassol, Cyprus
| | - Christakis Damianou
- Department of Electrical Engineering, Computer Engineering, and Informatics, Cyprus University of Technology, Limassol, Cyprus
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Zhong X, Zhou P, Zhao Y, Liu W, Zhang X. A novel tissue-mimicking phantom for US/CT/MR-guided tumor puncture and thermal ablation. Int J Hyperthermia 2022; 39:557-563. [PMID: 35379066 DOI: 10.1080/02656736.2022.2056249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
AIM This study aimed to develop a novel tumor-bearing tissue phantom model that can be used for US/CT/MR-guided tumor puncture and thermal ablation. METHODS The phantom model comprised two parts: a normal tissue-mimicking phantom and a tumor-mimicking phantom. A normal tissue phantom was prepared based on a polyacrylamide gel mixed with thermochromic ink. Moreover, a spherical phantom containing contrast agents was constructed and embedded in the tissue phantom to mimic a tumor lesion. US/CT/MR imaging features and thermochromic property of the phantom model were characterized. Finally, the utility of the phantom model for imaging-guided microwave ablation training was examined. RESULTS The tumor phantom containing contrast agents showed hyper-echogenicity, higher CT numbers, and lower T2 signal intensity compared with the normal tissue phantom in US/CT/MR images. Consequently, we could locate the position of the tumor in US/CT/MR imaging and perform an imaging-guided tumor puncture. When the temperature reached the threshold of 60 °C, the phantom exhibited a permanent color change from cream white to magenta. Based on this obvious color change, our phantom model could clearly map the thermal ablation region after thermotherapy. CONCLUSIONS We developed a novel US/CT/MR-imageable tumor-bearing tissue model that can be used for imaging-guided tumor puncture and thermal ablation. Furthermore, it allows visual assessment of the ablation region by analyzing the obvious color change. Overall, this phantom model could be a good training tool in the field of thermal ablation.
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Affiliation(s)
- Xinyu Zhong
- Department of Ultrasound, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Ping Zhou
- Department of Ultrasound, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Yongfeng Zhao
- Department of Ultrasound, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Wengang Liu
- Department of Ultrasound, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Xinghao Zhang
- Department of Ultrasound, The Third Xiangya Hospital, Central South University, Changsha, China
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Bock F, Bøtker JP, Larsen SW, Lu X, Østergaard J. Methodological Considerations in Development of UV Imaging for Characterization of Intra-Tumoral Injectables Using cAMP as a Model Substance. Int J Mol Sci 2022; 23:ijms23073599. [PMID: 35408971 PMCID: PMC8998202 DOI: 10.3390/ijms23073599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/17/2022] [Accepted: 03/23/2022] [Indexed: 12/19/2022] Open
Abstract
A UV imaging release-testing setup comprising an agarose gel as a model for tumorous tissue was developed. The setup was optimized with respect to agarose concentration (0.5% (w/v)), injection procedure, and temperature control. A repeatable injection protocol was established allowing injection into cavities with well-defined geometries. The effective resolution of the SDi2 UV imaging system is 30-80 µm. The linear range of the imaging system is less than that of typical spectrophotometers. Consequently, non-linear cAMP calibration curves were applied for quantification at 280 nm. The degree of deviation from Beer's law was affected by the background absorbance of the gel matrix. MATLAB scripts provided hitherto missing flexibility with respect to definition and utilization of quantification zones, contour lines facilitating visualization, and automated, continuous data analysis. Various release patterns were observed for an aqueous solution and in situ forming Pluronic F127 hydrogel and PLGA implants containing cAMP as a model for STING ligands. The UV imaging and MATLAB data analysis setup constituted a significant technical development in terms of visualizing behavior for injectable formulations intended for intra-tumoral delivery, and, thereby, a step toward establishment of a bio-predictive in vitro release-testing method.
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Affiliation(s)
- Frederik Bock
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark; (F.B.); (J.P.B.); (S.W.L.)
| | - Johan Peter Bøtker
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark; (F.B.); (J.P.B.); (S.W.L.)
| | - Susan Weng Larsen
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark; (F.B.); (J.P.B.); (S.W.L.)
| | - Xujin Lu
- Bristol Myers Squibb Company, Drug Product Development, 1 Squibb Drive, New Brunswick, NJ 08901, USA;
| | - Jesper Østergaard
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark; (F.B.); (J.P.B.); (S.W.L.)
- Correspondence: ; Tel.: +45-35336138
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Antoniou A, Damianou C. MR relaxation properties of tissue-mimicking phantoms. ULTRASONICS 2022; 119:106600. [PMID: 34627028 DOI: 10.1016/j.ultras.2021.106600] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
High quality tissue-mimicking phantoms (TMPs) have a critical role in the preclinical testing of emerging modalities for diagnosis and therapy. TMPs capable of accurately mimicking real tissue in Magnetic Resonance guided Focused Ultrasound (MRgFUS) applications should be fabricated with precise T1 and T2 relaxation times. Given the current popularity of the MRgFUS technology, we herein performed a systematic review on the MR relaxation properties of different phantoms types. Polyacrylamide (PAA) and agar based phantoms were proven capable of accurately replicating critical thermal, acoustical, and MR relaxation properties of various body tissues. Although gelatin phantoms were also proven factional in this regard, they lack the capacity to withstand ablation temperatures, and thus, are only recommended for hyperthermia applications. Other gelling agents identified in the literature are Poly-vinyl alcohol (PVA), Polyvinyl Chloride (PVC), silicone, and TX-150/ TX-151; however, their efficacy in thermal studies is yet to be established. PAA gels are favorable in that they offer optical transparency enabling direct visualization of coagulative lesions. On the other hand, agar phantoms have lower preparation costs and were proven very promising for use with the MRgFUS technology, without the toxicity issues related to the preparation and storage of PAA materials. Remarkably, agar turned out to be the prominent modifier of the T2 relaxation time even for phantoms containing other types of gelling agents instead of agar. This review could be useful in manufacturing realistic MRgFUS phantoms while simultaneously indicating an opportunity for further research in the field with a particular focus on the MR behavior of agar-based TMPs.
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Affiliation(s)
- Anastasia Antoniou
- Department of Electrical Engineering, Computer Engineering, and Informatics, Cyprus University of Technology, Limassol, Cyprus
| | - Christakis Damianou
- Department of Electrical Engineering, Computer Engineering, and Informatics, Cyprus University of Technology, Limassol, Cyprus.
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Holman R, Lorton O, Guillemin PC, Desgranges S, Santini F, Preso DB, Farhat M, Contino-Pépin C, Salomir R. Perfluorocarbon emulsion enhances MR-ARFI displacement and temperature in vitro: Evaluating the response with MRI, NMR, and hydrophone. Front Oncol 2022; 12:1025481. [PMID: 36713528 PMCID: PMC9880467 DOI: 10.3389/fonc.2022.1025481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 11/18/2022] [Indexed: 01/15/2023] Open
Abstract
Sonosensitive perfluorocarbon F8TAC18-PFOB emulsion is under development to enhance heating, increase thermal contrast, and reduce treatment times during focused ultrasound tumor ablation of highly perfused tissue. The emulsion previously showed enhanced heating during ex vivo and in vitro studies. Experiments were designed to observe the response in additional scenarios by varying focused ultrasound conditions, emulsion concentrations, and surfactants. Most notably, changes in acoustic absorption were assessed with MR-ARFI. Phantoms were developed to have thermal, elastic, and relaxometry properties similar to those of ex vivo pig tissue. The phantoms were embedded with varying amounts of F8TAC18-PFOB emulsion or lecithin-PFOB emulsion, between about 0.0-0.3% v:w, in 0.05% v:w increments. MR-ARFI measurements were performed using a FLASH-ARFI-MRT sequence to obtain simultaneous displacement and temperature measurements. A Fabry-Perot hydrophone was utilized to observe the acoustic emissions. Susceptibility-weighted imaging and relaxometry mapping were performed to observe concentration-dependent effects. 19F diffusion-ordered spectroscopy NMR was used to measure the diffusion coefficient of perfluorocarbon droplets in a water emulsion. Increased displacement and temperature were observed with higher emulsion concentration. In semi-rigid MR-ARFI phantoms, a linear response was observed with low-duty cycle MR-ARFI sonications and a mono-exponential saturating response was observed with sustained sonications. The emulsifiers did not have a significant effect on acoustic absorption in semi-rigid gels. Stable cavitation might also contribute to enhanced heating.
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Affiliation(s)
- Ryan Holman
- Image Guided Interventions Laboratory (GR-949), Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Orane Lorton
- Image Guided Interventions Laboratory (GR-949), Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Pauline C Guillemin
- Image Guided Interventions Laboratory (GR-949), Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Stéphane Desgranges
- Avignon Université, Equipe Systèmes Amphiphiles bioactifs et Formulations Eco-compatibles, Unité Propre de Recherche et d'Innovation (UPRI), Avignon, France
| | - Francesco Santini
- Department of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Davide Bernardo Preso
- Institute of Mechanical Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Mohamed Farhat
- Institute of Mechanical Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Christiane Contino-Pépin
- Avignon Université, Equipe Systèmes Amphiphiles bioactifs et Formulations Eco-compatibles, Unité Propre de Recherche et d'Innovation (UPRI), Avignon, France
| | - Rares Salomir
- Image Guided Interventions Laboratory (GR-949), Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Radiology Department, University Hospitals of Geneva, Geneva, Switzerland
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11
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Carlson CS, Postema M. Deep impact of superficial skin inking: acoustic analysis of underlying tissue. BIO INTEGRATION 2021. [DOI: 10.15212/bioi-2021-0004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Abstract Background: Skin tattoos are a common decoration, but profound scientific study whether the presence of a skin tattoo alters the acoustic response from superficial tissue, and therefore from underlying tissue, was previously lacking. Any image aberrations
caused by tattoo presence may have been thought negligible, yet empirically found artifacts in brightness-mode images of tattooed skin suggest otherwise. This study investigated the nature of these artifacts theoretically and experimentally in extremely simplified cases of perfectly flat and
homogenous layered media and in tattooed pork.Methods: Theory was derived for computing the acoustic response from horizontally and vertically layered media containing a thin inked layer. Experiments were performed in vitro. Artificial and pork skin were tattooed, attached to phantom
material, and sonicated with a 13‐6-MHz probe. The speed of sound of these materials was determined, and the perceived refraction angles was measured.Results: The measured speeds of sound of tattooed materials were higher than those of their uninked counterparts. The presence
of tattoo ink was found to have increased the linear acoustic attenuation by 1 dB/cm. This value is negligible for typical tattoos of only few millimeters. The perceived critical refraction angles of adjacent materials could be detected, and their corresponding speeds of sound were quantified.
These coincided with values derived from theory.Conclusion: The ratio of speeds of sound of adjacent materials was shown to create distinct highlights in brightness-mode images. The artifacts observed in in vitro and in vivo brightness-mode scans were explained from near-vertical
transitions between areas of different sound speed. This is the first study correlating so-called critical refraction highlighting with speed-of-sound information. In addition, it was found that phantom material is a room-temperature acoustic alternative for experiments on live human skin.
In summary, the presence of superficial tattoos has a small but quantifiable effect on the acoustic response from deeper tissues.
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Affiliation(s)
- Craig S. Carlson
- School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, 1 Jan Smuts Laan, 2050 Braamfontein, South Africa
| | - Michiel Postema
- School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, 1 Jan Smuts Laan, 2050 Braamfontein, South Africa
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Drakos T, Giannakou M, Menikou G, Constantinides G, Damianou C. Characterization of a soft tissue-mimicking agar/wood powder material for MRgFUS applications. ULTRASONICS 2021; 113:106357. [PMID: 33548756 DOI: 10.1016/j.ultras.2021.106357] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 12/29/2020] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
This study describes the development and characterization of an agar-based soft tissue-mimicking material (TMM) doped with wood powder destined for fabricating MRgFUS applications. The main objective of the following work was to investigate the suitability of wood powder as an inexpensive alternative in replacing other added materials that have been suggested in previous studies for controlling the ultrasonic properties of TMMs. The characterization procedure involved a series of experiments designed to estimate the acoustic (attenuation coefficient, absorption coefficient, propagation speed, and impedance), thermal (conductivity, diffusivity, specific heat capacity), and MR properties (T1 and T2 relaxation times) of the wood-powder doped material. The developed TMM (2% w/v agar and 4% w/v wood powder) as expected demonstrated compatibility with MRI scanner following images artifacts evaluation. The acoustic attenuation coefficient of the proposed material was measured over the frequency range of 1.1-3 MHz and found to be nearly proportional to frequency. The measured attenuation coefficient was 0.48 dB/cm at 1 MHz which was well within the range of soft tissue. Temperatures over 37 °C proved to increase marginally the attenuation coefficient. Following the transient thermoelectric method, the acoustic absorption coefficient was estimated at 0.34 dB/cm-MHz. The estimated propagation speed (1487 m/s) was within the range of soft tissue at room temperature, while it significantly increased with higher temperature. The material possessed an acoustic impedance of 1.58 MRayl which was found to be comparable to the corresponding value of muscle tissue. The thermal conductivity of the material was estimated at 0.51 W/m K. The measured relaxation times T1 (844 ms) and T2 (66 ms) were within the range of values found in the literature for soft tissue. The phantom was tested for its suitability for evaluating MRgFUS thermal protocols. High acoustic energy was applied, and temperature change was recorded using thermocouples and MR thermometry. MR thermal maps were acquired using single-shot Echo Planar Imaging (EPI) gradient echo sequence. The TMM matched adequately the acoustic and thermal properties of human tissues and through a series of experiments, it was proven that wood concentration enhances acoustic absorption. Experiments using MR thermometry demonstrated the usefulness of this phantom to evaluate ultrasonic thermal protocols by monitoring peak temperatures in real-time. Thermal lesions formed above a thermal dose were observed in high-resolution MR images and visually in dissections of the proposed TMM.
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Affiliation(s)
| | | | - Georgios Menikou
- Medical Physics Sector, State Health Services Organization, Nicosia General Hospital, Nicosia, Cyprus.
| | - Georgios Constantinides
- Department of Mechanical Engineering and Materials Science and Engineering, Cyprus University of Technology, Limassol, Cyprus.
| | - Christakis Damianou
- Department of Electrical Engineering, Computer Engineering and Informatics, Cyprus University of Technology, Limassol, Cyprus.
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Hofstetter LW, Odéen H, Bolster BD, Christensen DA, Payne A, Parker DL. Magnetic resonance shear wave elastography using transient acoustic radiation force excitations and sinusoidal displacement encoding. Phys Med Biol 2021; 66. [PMID: 33352538 DOI: 10.1088/1361-6560/abd5ce] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/22/2020] [Indexed: 12/31/2022]
Abstract
A magnetic resonance (MR) shear wave elastography technique that uses transient acoustic radiation force impulses from a focused ultrasound (FUS) transducer and a sinusoidal-shaped MR displacement encoding strategy is presented. Using this encoding strategy, an analytic expression for calculating the shear wave speed in a heterogeneous medium was derived. Green's function-based simulations were used to evaluate the feasibility of calculating shear wave speed maps using the analytic expression. Accuracy of simulation technique was confirmed experimentally in a homogeneous gelatin phantom. The elastography measurement was compared to harmonic MR elastography in a homogeneous phantom experiment and the measured shear wave speed values differed by less than 14%. This new transient elastography approach was able to map the position and shape of inclusions sized from 8.5 to 14 mm in an inclusion phantom experiment. These preliminary results demonstrate the feasibility of using a straightforward analytic expression to generate shear wave speed maps from MR images where sinusoidal-shaped motion encoding gradients are used to encode the displacement-time history of a transiently propagating wave-packet. This new measurement technique may be particularly well suited for performing elastography before, during, and after MR-guided FUS therapies since the same device used for therapy is also used as an excitation source for elastography.
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Affiliation(s)
- Lorne W Hofstetter
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Henrik Odéen
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Bradley D Bolster
- Siemens Medical Solutions USA, Inc., Salt Lake City, Utah, United States of America
| | - Douglas A Christensen
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, United States of America.,Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah, United States of America
| | - Allison Payne
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Dennis L Parker
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah, United States of America
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