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Xiao G, Jan C, Hong L, Ye J, Li N, Li Y, Zhong N, Li Y. Eye injuries caused by high intensity macro and micro focused ultrasound treatment: a case report. BMC Ophthalmol 2024; 24:390. [PMID: 39227863 PMCID: PMC11370310 DOI: 10.1186/s12886-024-03645-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 08/19/2024] [Indexed: 09/05/2024] Open
Abstract
BACKGROUND High Intensity Macro and Micro Focused Ultrasound ( HIFU) is a safe and effective method for the treatment of skin laxity. However, the application of high-intensity focused ultrasound energy on eyelids has been associated with potential ocular complications including traumatic cataract, iridocyclitis, and conjunctival hemorrhage, among others. CASE PRESENTATION A 40-year-old female developed blurred vision in her left eye after receiving HIFU treatment on binocular eyelids, and her left far vision was 20/66. The examination revealed left eye iris depigmentation and conjunctival hemorrhage. Both eyes exhibited multiple white streaking or tadpole-shaped opacities in the lenses. CONCLUSION Excessive ultrasonic energy generated by HIFU can cause protein denaturation, leading to conditions such as traumatic cataract, visual impairment, injuries to the iris and conjunctiva when applied to the eyes. We recommend that individuals undergoing cosmetic treatment in the periorbital region should be highly aware of the possible ocular side effects.
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Affiliation(s)
- Guobei Xiao
- Department of Ophthalmology, The First Hospital of Nanchang, Jiangxi, 330006, China
| | - Catherine Jan
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Ophthalmology, Department of Surgery, Faculty of Medicine, Dentistry & Health Sciences, University of Melbourne, Melbourne, Australia
| | - Ling Hong
- Department of Ophthalmology, The First Hospital of Nanchang, Jiangxi, 330006, China
| | - Jinglei Ye
- Third Clinical Medicine Faculty, Nanchang University, Jiangxi, 330031, China
| | - Ning Li
- Department of Ophthalmology, The First Hospital of Nanchang, Jiangxi, 330006, China
| | - Yuxuan Li
- Third Clinical Medicine Faculty, Nanchang University, Jiangxi, 330031, China
| | - Na Zhong
- Third Clinical Medicine Faculty, Nanchang University, Jiangxi, 330031, China
| | - Yingjie Li
- Department of Ophthalmology, The First Hospital of Nanchang, Jiangxi, 330006, China.
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Zheng S, Wang D, Huang Z, Wang Z, Liu Y, Chen L, Jin L, Tan Y, Lin M, Zuo C. The Agreement of the Nomogram Tool and Ultrasound Biomicroscopy Images in Calculating Ultrasound Cycloplasty Probe Model in Chinese Patients. Ophthalmic Res 2023; 66:1191-1197. [PMID: 37463571 PMCID: PMC10614504 DOI: 10.1159/000530992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 03/27/2023] [Indexed: 07/20/2023]
Abstract
PURPOSE The aim of the study was to compare and explore the agreement between the nomogram tool and ultrasound biomicroscopy (UBM) images method to calculate the ultrasound cycloplasty (UCP) probe model in Chinese glaucoma patients. METHODS Retrospective analysis of Chinese glaucoma patients who visited Zhongshan Ophthalmic Center in Guangzhou from January to December 2019 and were eligible for UCP surgery. Visual acuity, intraocular pressure (IOP), ocular axial length (AL), and horizontal corneal diameter (white to white [WTW]) were measured. UBM images with clear ciliary body imaging and AL and WTW data were sent to trained personnel for probe model measurements. The data calculated by both methods were analyzed using unweighted and weighted κ statistics. The level of agreement refers to Landis and Koch's guideline for the strength of agreement indicated with weighted κ values. RESULTS 1,061 eyes of 642 patients were involved, with a mean age of 61.66 ± 11.66 years. Their best-corrected visual acuity converted to logarithm of minimal-angle-of-resolution (logMAR) scores of -0.18-3.00 with a mean value of 0.69 ± 0.77. IOP was 22.0-60.0 mm Hg with a mean of 27.97 ± 5.66 mm Hg. The mean AL and WTW were 22.88 ± 1.33 (19.15-32.14) mm and 11.52 ± 0.49 (10.00-12.90) mm, respectively. The agreement between the two methods was fair (weighted κ = 0.299), matching in 62.86% of eyes (weighted κ = 0.299, κ = 0.264). The agreement in primary open angle glaucoma, acute primary angle-closure glaucoma, chronic primary angle-closure glaucoma, and secondary glaucoma patients was 60.85% (weighted κ = 0.336, κ = 0.301), 65.06% (weighted κ = 0.146, κ = 0.127), 62.26% (weighted κ = 0.204, κ = 0.184), and 57.97% (weighted κ = 0.332, κ = 0.280) of eyes, respectively. CONCLUSION The agreement between UBM images and the nomogram tool to calculate the UCP probe model of Chinese patients is at a fair level. The nomogram tool prefers to use larger probes. Improvements to the nomogram tool, such as including data from more ethnic groups and being able to calculate separately for different types of glaucoma, are needed to improve accuracy. The inclusion of parameters or images from more directions of the eye may help measure probe models more accurately for both the nomogram tool and the UBM image measurement.
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Affiliation(s)
- Shaoyang Zheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Dingqiao Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Zhihong Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Zhenyu Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Yuan Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Liming Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Ling Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Yuheng Tan
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Mingkai Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Chengguo Zuo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Guangdong Provincial Clinical Research Center for Ocular Diseases, Sun Yat-sen University, Guangzhou, China
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Rousou C, van Kronenburg N, Sonnen AFP, van Dijk M, Moonen C, Storm G, Mastrobattista E, Deckers R. Microbubble-Assisted Ultrasound for Drug Delivery to the Retina in an Ex Vivo Eye Model. Pharmaceutics 2023; 15:1220. [PMID: 37111705 PMCID: PMC10141545 DOI: 10.3390/pharmaceutics15041220] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/02/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
Drug delivery to the retina is one of the major challenges in ophthalmology due to the biological barriers that protect it from harmful substances in the body. Despite the advancement in ocular therapeutics, there are many unmet needs for the treatment of retinal diseases. Ultrasound combined with microbubbles (USMB) was proposed as a minimally invasive method for improving delivery of drugs in the retina from the blood circulation. This study aimed to investigate the applicability of USMB for the delivery of model drugs (molecular weight varying from 600 Da to 20 kDa) in the retina of ex vivo porcine eyes. A clinical ultrasound system, in combination with microbubbles approved for clinical ultrasound imaging, was used for the treatment. Intracellular accumulation of model drugs was observed in the cells lining blood vessels in the retina and choroid of eyes treated with USMB but not in eyes that received ultrasound only. Specifically, 25.6 ± 2.9% of cells had intracellular uptake at mechanical index (MI) 0.2 and 34.5 ± 6.0% at MI 0.4. Histological examination of retinal and choroid tissues revealed that at these USMB conditions, no irreversible alterations were induced at the USMB conditions used. These results indicate that USMB can be used as a minimally invasive targeted means to induce intracellular accumulation of drugs for the treatment of retinal diseases.
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Affiliation(s)
- Charis Rousou
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Heidelberglaan 8, 3584 CS Utrecht, The Netherlands
- Imaging and Oncology Division, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Nicky van Kronenburg
- Department of Translational Neuroscience, Brain Center, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Andreas F. P. Sonnen
- Department of Pathology, Division of Laboratories, Pharmacy and Biomedical Genetics, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Marijke van Dijk
- Department of Pathology, Division of Laboratories, Pharmacy and Biomedical Genetics, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Chrit Moonen
- Imaging and Oncology Division, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Gert Storm
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Heidelberglaan 8, 3584 CS Utrecht, The Netherlands
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Department of Biomaterials Science and Technology, University of Twente, 7500 AE Enschede, The Netherlands
| | - Enrico Mastrobattista
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Heidelberglaan 8, 3584 CS Utrecht, The Netherlands
| | - Roel Deckers
- Imaging and Oncology Division, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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Dabbagh A, Abdullah BJJ, Ramasindarum C, Abu Kasim NH. Tissue-mimicking gel phantoms for thermal therapy studies. ULTRASONIC IMAGING 2014; 36:291-316. [PMID: 24626566 DOI: 10.1177/0161734614526372] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Tissue-mimicking phantoms that are currently available for routine biomedical applications may not be suitable for high-temperature experiments or calibration of thermal modalities. Therefore, design and fabrication of customized thermal phantoms with tailored properties are necessary for thermal therapy studies. A multitude of thermal phantoms have been developed in liquid, solid, and gel forms to simulate biological tissues in thermal therapy experiments. This article is an attempt to outline the various materials and techniques used to prepare thermal phantoms in the gel state. The relevant thermal, electrical, acoustic, and optical properties of these phantoms are presented in detail and the benefits and shortcomings of each type are discussed. This review could assist the researchers in the selection of appropriate phantom recipes for their in vitro study of thermal modalities and highlight the limitations of current phantom recipes that remain to be addressed in further studies.
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Affiliation(s)
- Ali Dabbagh
- Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia University of Malaya Research Imaging Centre, University of Malaya, Kuala Lumpur, Malaysia
| | - Basri Johan Jeet Abdullah
- Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia University of Malaya Research Imaging Centre, University of Malaya, Kuala Lumpur, Malaysia
| | - Chanthiriga Ramasindarum
- Biomaterials Technology Research Group, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia Dental Research Management Centre, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
| | - Noor Hayaty Abu Kasim
- Biomaterials Technology Research Group, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia Department of Restorative Dentistry, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
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Simon LH, Wilkens V, Fedtke T, Beyer M. Ignition of dust-air atmospheres by ultrasonic waves. J Loss Prev Process Ind 2013. [DOI: 10.1016/j.jlp.2013.08.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
Therapeutic ultrasound, although less well known than ultrasound for diagnostic imaging, has become a topic of growing interest in ophthalmology. High intensity focused ultrasound (HIFU) for the treatment of glaucoma and ultrasonic drug delivery are the two main areas of research and potential clinical applications. For the treatment of glaucoma, the specific advantage of HIFU, particularly when compared to the laser, is that the energy can be focused through optically opaque media, especially through the sclera which is a strongly light-scattering medium. HIFU is therefore a possible method for partial coagulation of the ciliary body (an anatomical structure responsible for the production of the liquid filling the eye) and, hence, reducing intraocular pressure and the risk of glaucoma. Ocular drug bioavailability also remains a challenge, being limited by multiple barriers to drug entry and lacrimal drainage, and making it difficult to achieve a sufficient drug concentration for numerous diseases of the front and back of the eye. As the front wall of the eye (cornea and anterior sclera) is a pathway for topically applied drugs, locally applied ultrasound has been proposed as a way of enhancing the delivery and activity of drugs and genes. Despite the fact that experimental studies seem to confirm the potential benefit of ultrasound ocular drug delivery, there is still a lack of clinical evidence. The aim of this contribution is to provide an update on recent advances in the field of therapeutic ultrasound in ophthalmology.
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Park J, Zhang Y, Vykhodtseva N, Akula JD, McDannold NJ. Targeted and reversible blood-retinal barrier disruption via focused ultrasound and microbubbles. PLoS One 2012; 7:e42754. [PMID: 22912733 PMCID: PMC3418291 DOI: 10.1371/journal.pone.0042754] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 07/10/2012] [Indexed: 02/06/2023] Open
Abstract
The blood-retinal barrier (BRB) prevents most systemically-administered drugs from reaching the retina. This study investigated whether burst ultrasound applied with a circulating microbubble agent can disrupt the BRB, providing a noninvasive method for the targeted delivery of systemically administered drugs to the retina. To demonstrate the efficacy and reversibility of such a procedure, five overlapping targets around the optic nerve head were sonicated through the cornea and lens in 20 healthy male Sprague-Dawley rats using a 690 kHz focused ultrasound transducer. For BRB disruption, 10 ms bursts were applied at 1 Hz for 60 s with different peak rarefactional pressure amplitudes (0.81, 0.88 and 1.1 MPa). Each sonication was combined with an IV injection of a microbubble ultrasound contrast agent (Definity). To evaluate BRB disruption, an MRI contrast agent (Magnevist) was injected IV immediately after the last sonication, and serial T1-weighted MR images were acquired up to 30 minutes. MRI contrast enhancement into the vitreous humor near targeted area was observed for all tested pressure amplitudes, with more signal enhancement evident at the highest pressure amplitude. At 0.81 MPa, BRB disruption was not detected 3 h post sonication, after an additional MRI contrast injection. A day after sonication, the eyes were processed for histology of the retina. At the two lower exposure levels (0.81 and 0.88 MPa), most of the sonicated regions were indistinguishable from the control eyes, although a few tiny clusters of extravasated erythrocytes (petechaie) were observed. More severe retinal damage was observed at 1.1 MPa. These results demonstrate that focused ultrasound and microbubbles can offer a noninvasive and targeted means to transiently disrupt the BRB for ocular drug delivery.
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Affiliation(s)
- Juyoung Park
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| | - Yongzhi Zhang
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Natalia Vykhodtseva
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - James D. Akula
- Department of Ophthalmology, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Nathan J. McDannold
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
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Charrel T, Aptel F, Birer A, Chavrier F, Romano F, Chapelon JY, Denis P, Lafon C. Development of a miniaturized HIFU device for glaucoma treatment with conformal coagulation of the ciliary bodies. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:742-754. [PMID: 21439719 DOI: 10.1016/j.ultrasmedbio.2011.01.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 01/06/2011] [Accepted: 01/23/2011] [Indexed: 05/30/2023]
Abstract
This study examined the feasibility of high-intensity focused ultrasound (HIFU) for glaucoma treatment with conformal coagulation of the ciliary bodies (CB). A miniaturized high frequency (21 MHz) device was developed, based on the geometry of the eye and adapted to the anatomy of the rabbit eyeball. Six line-focus lesions were distributed along a circle and produced by six cylindrical transducers. To be conformal, the numerical model predicted an intensity of 6.9 W/cm(2), with exposure duration of 3 s ON (powered per sector). In vivo experiments were conducted on two rabbits. A significant intraocular pressure reduction was noted (-45% and -31%). Histology demonstrated conformal and homogeneous coagulation of the CB without side effects.
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Abstract
PURPOSE Density is essential for acoustic characterization of tissues and provides a basic input for ultrasound backscatter and absorption models. Despite the existence of extensive compilations of acoustic properties, neither unified data on ocular density nor comparisons of the densities between all ocular components can be found. This study was undertaken to determine the mass density of all the ocular components of the bovine eye. METHODS Liquid components were measured through mass/volume ratio, whereas solid tissues were measured with two different densitometry techniques based on Archimedes Principle. The first method determines the density by measuring dry and wet weight of the tissues. The second method consists of immersing the tissues in sucrose solutions of varying densities and observing their buoyancy. RESULTS Although the mean densities for all tissues were found to be within 0.02 g/cm by both methods, only the sucrose solution method offered a consistent relative order for all measured ocular components, as well as a considerably smaller standard deviation (a maximum standard deviation of 0.004 g/cm for cornea). The lens was found to be the densest component, followed by the sclera, cornea, choroid, retina, aqueous, and vitreous humors. CONCLUSIONS The consistent results of the sucrose solution tests suggest that the ocular mass density is a physical property that is more dependent on the compositional and structural characteristics of the tissue and than on population variability.
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Labuda CP, Church CC. Augmentation of HIFU-induced heating with fibers embedded in a phantom. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:442-449. [PMID: 21316561 DOI: 10.1016/j.ultrasmedbio.2010.12.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 12/16/2010] [Accepted: 12/21/2010] [Indexed: 05/28/2023]
Abstract
The effect of fibers on the rate of heat deposition in the focal region of high-intensity focused ultrasound (HIFU) beams was investigated. Nylon, stainless steel and copper fibers of diameters 0.23-0.25, 0.33 and 0.51-0.53 mm embedded in a phantom were exposed to HIFU. The total energy deposited was quantified by measuring the volumes of the lesions formed. The average volumes of the lesions normalized to the average volume of control lesions were 1.19±0.19, 1.43±0.19 and 2.67±0.21 for increasing nylon fiber diameter, indicating an augmented rate of heating. The maximum normalized volume of lesions at the metal fibers was 0.655. These results are consistent with the material properties, which suggest that the mechanism is increased acoustic absorption along with reduction of heat loss by the nylon fiber. The study supports the possibility of improving the efficacy of HIFU-induced hemostasis in vivo by use of a specially designed, nylon fiber-based medical appliance.
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Affiliation(s)
- Cecille Pemberton Labuda
- Department of Physics and Astronomy and the National Center for Physical Acoustics, University of Mississippi, University, MS 38677, USA.
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Wang S, Zderic V, Frenkel V. Extracorporeal, low-energy focused ultrasound for noninvasive and nondestructive targeted hyperthermia. Future Oncol 2011; 6:1497-511. [PMID: 20919832 DOI: 10.2217/fon.10.101] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The benefits of hyperthermia are well known as both a primary treatment modality and adjuvant therapy for treating cancer. Among the different techniques available, high-intensity focused ultrasound is the only noninvasive modality that can provide local hyperthermia precisely at a targeted location at any depth inside the body using image guidance. Traditionally, focused ultrasound exposures have been provided at high rates of energy deposition for thermal ablation of benign and malignant tumors. At present, exposures are being evaluated in pulsed mode, which lower the rates of energy deposition and generate primarily mechanical effects for enhancing tissue permeability to improve local drug delivery. These pulsed exposures can be modified for low-level hyperthermia as an adjuvant therapy for drug and gene delivery applications, as well as for more traditional applications such as radiosensitization. In this review, we discuss the manner by which focused ultrasound exposures at low rates of energy deposition are being developed for a variety of clinically translatable applications for the treatment of cancer. Specific preclinical studies will be highlighted. Additional information will also be provided for optimizing these exposures, including computer modeling and simulations. Various techniques for monitoring temperature elevations generated by focused ultrasound will also be reviewed.
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Affiliation(s)
- Shutao Wang
- Department of Radiology & Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
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Maxwell AD, Wang TY, Yuan L, Duryea AP, Xu Z, Cain CA. A tissue phantom for visualization and measurement of ultrasound-induced cavitation damage. ULTRASOUND IN MEDICINE & BIOLOGY 2010; 36:2132-43. [PMID: 21030142 PMCID: PMC2997329 DOI: 10.1016/j.ultrasmedbio.2010.08.023] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 08/18/2010] [Accepted: 08/30/2010] [Indexed: 05/03/2023]
Abstract
Many ultrasound studies involve the use of tissue-mimicking materials to research phenomena in vitro and predict in vivo bioeffects. We have developed a tissue phantom to study cavitation-induced damage to tissue. The phantom consists of red blood cells suspended in an agarose hydrogel. The acoustic and mechanical properties of the gel phantom were found to be similar to soft tissue properties. The phantom's response to cavitation was evaluated using histotripsy. Histotripsy causes breakdown of tissue structures by the generation of controlled cavitation using short, focused, high-intensity ultrasound pulses. Histotripsy lesions were generated in the phantom and kidney tissue using a spherically focused 1-MHz transducer generating 15 cycle pulses, at a pulse repetition frequency of 100 Hz with a peak negative pressure of 14 MPa. Damage appeared clearly as increased optical transparency of the phantom due to rupture of individual red blood cells. The morphology of lesions generated in the phantom was very similar to that generated in kidney tissue at both macroscopic and cellular levels. Additionally, lesions in the phantom could be visualized as hypoechoic regions on a B-mode ultrasound image, similar to histotripsy lesions in tissue. High-speed imaging of the optically transparent phantom was used to show that damage coincides with the presence of cavitation. These results indicate that the phantom can accurately mimic the response of soft tissue to cavitation and provide a useful tool for studying damage induced by acoustic cavitation.
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Affiliation(s)
- Adam D Maxwell
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109-2099, USA.
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