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Arikan Y, Eksi M, Sungur U, Yoldas M, Keskin MZ. Variation coefficient of stone density and renal cortical thickness: the parameters evaluating non-contrast computed tomography imaging for predict extracorporeal shock wave lithotripsy success. Urolithiasis 2024; 52:53. [PMID: 38564004 DOI: 10.1007/s00240-024-01561-8] [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: 01/30/2024] [Accepted: 03/18/2024] [Indexed: 04/04/2024]
Abstract
The stone density (SD) is not the same in all parts of the stone due to the heterogeneous nature of the stone and the shock wave (SW) passes through tissues of many different densities until it reaches the stone. These factors affect the success of Extracorporeal Shock Wave Lithotripsy (ESWL). We aimed to evaluate the effect of the Variation Coefficient of Stone Density (VCSD) and Renal Cortical Tickness (RCT) on the success of ESWL. Between 2020 and 2023, 510 patients who underwent ESWL were divided into 2 groups treatment success (n:304) and treatment failure (n:206). Non-Contrast Computed Tomography (NCCT) imaging values of hydronephrosis degree of the kidney, stone location, stone volume (SV), stone-skin distance (SSD), SD, Standard deviation of Stone Density (SDSD), VCSD, RCT, Soft-Tissue Thickness (STT), Muscle Thickness (MT) were analyzed. VCSD value was obtained by dividing SDSD by SD. Along the SW, tissues were divided into three components: kidney (renal cortex), muscle and other soft tissues. RCT, MT and SSD were measured at three different angles (0°, 45°, and 90°) and these 3 lengths were averaged. In univariate analysis, Body Mass Index (BMI), SV, SD, VCSD, SSD, RCT and STT were demonstrated to affect ESWL success. In multivariate analysis, low BMI, SV, SD, RCT and large VCSD were significant independent predictors of ESWL success. Among these parameters, VCSD had the highest prediction accuracy, followed by SD, SV, RCT and BMI, respectively. This study demonstrated that VCSD value and RCT are predictive parameters in determining the treatment of patients with urinary calculi and selecting suitable ESWL candidates.
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Affiliation(s)
- Yusuf Arikan
- Department of Urology, Izmir Tepecik Training and Research Hospital, Izmir, Turkey.
| | - Mithat Eksi
- Department of Urology, University of Health Sciences, Istanbul Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Istanbul, Turkey
| | - Ubeyd Sungur
- Department of Urology, University of Health Sciences, Istanbul Bakirkoy Dr. Sadi Konuk Training and Research Hospital, Istanbul, Turkey
| | - Mehmet Yoldas
- Department of Urology, Izmir Tepecik Training and Research Hospital, Izmir, Turkey
| | - Mehmet Zeynel Keskin
- Department of Urology, Izmir Tepecik Training and Research Hospital, Izmir, Turkey
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Owen K, Joe W, Ivander A, Palgunadi IN, Adhyatma KP. Role of Noncontrast Computed Tomography Parameters in Predicting the Outcome of Extracorporeal Shock Wave Lithotripsy for Upper Urinary Stones Cases: A Meta-analysis. Acad Radiol 2023:S1076-6332(23)00556-1. [PMID: 37985292 DOI: 10.1016/j.acra.2023.10.021] [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: 08/31/2023] [Revised: 10/09/2023] [Accepted: 10/10/2023] [Indexed: 11/22/2023]
Abstract
RATIONALE Extracorporeal shock wave lithotripsy (ESWL) is widely considered the primary approach for managing urinary tract stones. This study aimed to assess the predictive factors associated with non-contrast computed tomography (NCCT)-based parameters of upper urinary stones in relation to the outcomes of ESWL. MATERIALS AND METHODS A systematic search was conducted in PubMed, ScienceDirect, Web of Science, and Cochrane Library to identify all relevant studies published up to June 3, 2023. Several NCCT-based parameters to predict ESWL outcomes, comprised of mean stone density (MSD), skin-to-stone distance (SSD), and stone size, were extracted and analyzed using Review Manager software. RESULTS Out of 979 publications screened, a total of 39 publications, involving 7869 patients, were enrolled in the analysis. The pooled estimate demonstrated significant differences between MSD, and stone size between successful and failure of stone fragmentation groups, in which lower values of these parameters are associated with successful ESWL outcomes. CONCLUSION The results from the current study suggested that lower NCCT parameters, notably MSD, SSD, and stone size, are significantly associated with successful ESWL outcome. However, additional large-scale prospective studies are required to utilize these parameters effectively, and the optimal cutoff value should be determined.
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Affiliation(s)
- Kevin Owen
- Bangli General Hospital, Bangli, Indonesia (K.O.).
| | - Wilbert Joe
- Regional Public Hospital dr.M. Thomsen Nias, Gunungsitoli, Indonesia (W.J.)
| | - Alvin Ivander
- Faculty of Medicine, Universitas Sumatera Utara, Medan, Indonesia (A.I.)
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Connors BA, Schaefer RB, Gallagher JJ, Johnson CD, Li G, Handa RK, Evan AP. Preliminary Report on Stone Breakage and Lesion Size Produced by a New Extracorporeal Electrohydraulic (Sparker Array) Discharge Device. Urology 2018; 116:213-217. [PMID: 29596866 DOI: 10.1016/j.urology.2018.03.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 03/08/2018] [Accepted: 03/15/2018] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To determine if an innovative extracorporeal electrohydraulic shock wave (SW) device (sparker array [SPA]) can effectively fracture artificial stones in vitro and in vivo, and if SPA treatment produces a renal lesion in our pig model of lithotripsy injury. Results of these experiments will be used to help evaluate the suitability of this device as a clinical lithotripter. MATERIALS AND METHODS Ultracal-30 artificial stones were placed in a holder at the focus of the SPA and treated with 600 SWs (21.6 kV, 60 shocks/min). Stone fragments were collected, dried, and weighed to determine stone breakage. In vivo stone breakage entailed implanting stones into pigs. These stones were treated with 600 or 1200 SWs and the fragments were collected for analysis. Lesion analysis consisted of treating the left kidney of pigs with 1200 or 2400 SWs and quantitating the hemorrhagic lesion. RESULTS In vitro, 71% ± 2% of each artificial stone was fractured to <2 mm in size. In vivo stone breakage averaged 63%. Renal injury analysis revealed that only 1 of 7 kidneys showed evidence of hemorrhagic injury in the treated area. CONCLUSION The SPA consistently comminuted artificial stones demonstrating its ability to fracture stones like other lithotripters. Also, the SPA caused little to no renal injury at the settings used in this study. These findings suggest further research is warranted to determine the potential of this device as a clinical lithotripter.
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Affiliation(s)
- Bret A Connors
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN.
| | | | | | - Cynthia D Johnson
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN
| | - Guangyan Li
- School of Physics, Northeast Normal University, Changchun, China
| | - Rajash K Handa
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN
| | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN
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López-Marín LM, Rivera AL, Fernández F, Loske AM. Shock wave-induced permeabilization of mammalian cells. Phys Life Rev 2018; 26-27:1-38. [PMID: 29685859 DOI: 10.1016/j.plrev.2018.03.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/12/2018] [Accepted: 02/26/2018] [Indexed: 12/18/2022]
Abstract
Controlled permeabilization of mammalian cell membranes is fundamental to develop gene and cell therapies based on macromolecular cargo delivery, a process that emerged against an increasing number of health afflictions, including genetic disorders, cancer and infections. Viral vectors have been successfully used for macromolecular delivery; however, they may have unpredictable side effects and have been limited to life-threatening cases. Thus, several chemical and physical methods have been explored to introduce drugs, vaccines, and nucleic acids into cells. One of the most appealing physical methods to deliver genes into cells is shock wave-induced poration. High-speed microjets of fluid, emitted due to the collapse of microbubbles after shock wave passage, represent the most significant mechanism that contributes to cell membrane poration by this technique. Herein, progress in shock wave-induced permeabilization of mammalian cells is presented. After covering the main concepts related to molecular strategies whose applications depend on safer drug delivery methods, the physics behind shock wave phenomena is described. Insights into the use of shock waves for cell membrane permeation are discussed, along with an overview of the two major biomedical applications thereof-i.e., genetic modification and anti-cancer shock wave-assisted chemotherapy. The aim of this review is to summarize 30 years of data showing underwater shock waves as a safe, noninvasive method for macromolecular delivery into mammalian cells, encouraging the development of further research, which is still required before the introduction of this promising tool into clinical practice.
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Affiliation(s)
- Luz M López-Marín
- Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, 76230 Querétaro, Qro., Mexico.
| | - Ana Leonor Rivera
- Instituto de Ciencias Nucleares & Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Ciudad de México, Mexico.
| | - Francisco Fernández
- Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, 76230 Querétaro, Qro., Mexico.
| | - Achim M Loske
- Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, 76230 Querétaro, Qro., Mexico.
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Liu Y, Chen X, Guo A, Liu S, Hu G. Quantitative Assessments of Mechanical Responses upon Radial Extracorporeal Shock Wave Therapy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2018; 5:1700797. [PMID: 29593978 PMCID: PMC5867036 DOI: 10.1002/advs.201700797] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Indexed: 05/03/2023]
Abstract
Although radial extracorporeal shock wave therapy (rESWT) has been widely used to treat orthopedic disorders with promising clinical results, rESWT largely relies on clinicians' personal experiences and arbitrary judgments, without knowing relationships between administration doses and effective doses at target sites. In fact, practitioners lack a general and reliable way to assess propagation and distribution of pressure waves inside biological tissues quantitatively. This study develops a methodology to combine experimental measurements and computational simulations to obtain pressure fields from rESWT through calibrating and validating computational models with experimental measurements. Wave pressures at the bottom of a petri dish and inside biological tissues are measured, respectively, by attaching and implanting flexible membrane sensors. Detailed wave dynamics are simulated through explicit finite element analyses. The data decipher that waves from rESWT radiate directionally and can be modeled as acoustic waves generated from a vibrating circular piston. Models are thus established to correlate pressure amplitudes at the bottom of petri dishes and in the axial direction of biological tissues. Additionally, a pilot simulation upon rESWT for human lumbar reveals a detailed and realistic pressure field mapping. This study will open a new avenue of personalized treatment planning and mechanism research for rESWT.
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Affiliation(s)
- Yajun Liu
- Orthopedic Shock Wave Treatment CenterSpine Surgery DepartmentBeijing Jishuitan HospitalBeijing100035China
| | - Xiaodong Chen
- The State Key Laboratory of Nonlinear MechanicsBeijing Key Laboratory of Engineered Construction and MechanobiologyInstitute of MechanicsChinese Academy of SciencesBeijing100190China
- School of Engineering ScienceUniversity of Chinese Academy of SciencesBeijing100049China
| | - Anyi Guo
- Orthopedic Shock Wave Treatment CenterSpine Surgery DepartmentBeijing Jishuitan HospitalBeijing100035China
| | - Sijin Liu
- The State Key Laboratory of Environmental Chemistry and EcotoxicologyResearch Center for Eco‐Environmental SciencesChinese Academy of SciencesBeijing100085China
| | - Guoqing Hu
- The State Key Laboratory of Nonlinear MechanicsBeijing Key Laboratory of Engineered Construction and MechanobiologyInstitute of MechanicsChinese Academy of SciencesBeijing100190China
- School of Engineering ScienceUniversity of Chinese Academy of SciencesBeijing100049China
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Cirovic S, Gould DH, Park DH, Solan MC. Cadaveric experiments to evaluate pressure wave generated by radial shockwave treatment of plantar fasciitis. Foot Ankle Surg 2017; 23:285-289. [PMID: 29202989 DOI: 10.1016/j.fas.2016.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 07/28/2016] [Accepted: 08/18/2016] [Indexed: 02/04/2023]
Abstract
BACKGROUND Shockwave treatment is increasingly used for plantar fasciitis and Achilles tendinopathy. To be effective it is believed that high pressure must be achieved in the tissues. We report on the first human cadaveric experiments to characterize pressure from radial shockwave therapy (rSWT) for plantar fasciitis. METHODS The pressure from rSWT was measured in two cadaveric feet using a needle hydrophone. Maximal pressure and energy flux were calculated from the measurements. RESULTS The pressure persisted longer than supposed, for up to 400μs. The peak negative pressure was up to two Mega Pascal. The predicted energy in the tissue strongly depended on the time interval used in calculations. CONCLUSIONS The measured pressure may be sufficiently high to cause cavitation in the tissue, which is one of the proposed healing mechanisms associated with rSWT. The results suggest that the energy is imparted to the tissues for much longer than previously thought.
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Affiliation(s)
- Srdjan Cirovic
- The Centre for Biomedical Engineering, Department of Mechanical Engineering Sciences, University of Surrey, Stag Hill, Guildford GU2 7XH, UK.
| | - David H Gould
- The Centre for Biomedical Engineering, Department of Mechanical Engineering Sciences, University of Surrey, Stag Hill, Guildford GU2 7XH, UK
| | - Derek H Park
- Trauma and Orthopaedic Surgery Department, Barnet Hospital, Wellhouse Lane, Barnet, London EN5 3DJ, UK
| | - Matthew C Solan
- The Centre for Biomedical Engineering, Department of Mechanical Engineering Sciences, University of Surrey, Stag Hill, Guildford GU2 7XH, UK; Department of Orthopeadic Surgery, Royal Surrey County Hospital, Egerton Road, Guildford GU2 7XX, UK
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Wang JC, Zhou Y. Shifting the Split Reflectors to Enhance Stone Fragmentation of Shock Wave Lithotripsy. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:1876-1889. [PMID: 27166016 DOI: 10.1016/j.ultrasmedbio.2016.03.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/21/2016] [Accepted: 03/28/2016] [Indexed: 06/05/2023]
Abstract
Shock wave lithotripsy (SWL) has been used widely in urology for about three decades to treat kidney calculi. Technical development to improve performance (i.e., stone fragmentation efficiency) is continuous. Low-pressure wide-focus lithotripters have already achieved promising results. In this study, the lithotripter field and profile of lithotripter shock waves were changed simultaneously using a cost-effective and convenient design. An intact parabolic reflector was split into four pieces, and each part was moved individually. By shifting the split reflectors, the focused acoustic beams were separated. As a result, the beam width in the focal region could be increased. Both numerical models of wave propagation using a k-wave approach and hydrophone measurements showed similar pressure waveforms at the focus and the distributions along and transverse to the lithotripter axis. The increase of the shifting distance from 0 mm to 7 mm resulted in the increase of -6 dB beam width from 7.1 mm to 13.9 mm and location of tensile peak on axis moving from z = -14 mm to 1 mm. The Lithotripters at 10 kV (intact reflector) and at 12 kV with the split reflectors shifted by 5 mm were compared with each other because of their similar peak positive pressures at the focus (8.07 MPa ± 0.05 MPa vs. 7.90 MPa ± 0.11 MPa, respectively). However, there were significant differences in their positive beam width (8.7 mm vs. 10.2 mm), peak negative pressure (-6.34 MPa ± 0.04 MPa vs. -7.13 MPa ± 0.13 MPa), the maximum tensile stress (7.55 MPa vs. 8.95 MPa) and shear stress (6.1 MPa vs. 7.76 MPa) in a 10-mm diameter spherical stone and bubble collapse time (127.6 μs ± 5.4 μs vs. 212.7 μs ± 8.2 μs). As a result, stone fragmentation efficiency was enhanced about 1.8-fold (57.9% ± 4.6% vs. 32.2% ± 5.6%, p < 0.05) when shifting the split reflectors. These results suggest that this new reflector design could change the characteristics of the lithotripter field and increase stone fragmentation efficiency.
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Affiliation(s)
- Jen-Chieh Wang
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore
| | - Yufeng Zhou
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
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Ghorbani M, Oral O, Ekici S, Gozuacik D, Kosar A. Review on Lithotripsy and Cavitation in Urinary Stone Therapy. IEEE Rev Biomed Eng 2016; 9:264-83. [PMID: 27249837 DOI: 10.1109/rbme.2016.2573381] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cavitation is the sudden formation of vapor bubbles or voids in liquid media and occurs after rapid changes in pressure as a consequence of mechanical forces. It is mostly an undesirable phenomenon. Although the elimination of cavitation is a major topic in the study of fluid dynamics, its destructive nature could be exploited for therapeutic applications. Ultrasonic and hydrodynamic sources are two main origins for generating cavitation. The purpose of this review is to give the reader a general idea about the formation of cavitation phenomenon and existing biomedical applications of ultrasonic and hydrodynamic cavitation. Because of the high number of the studies on ultrasound cavitation in the literature, the main focus of this review is placed on the lithotripsy techniques, which have been widely used for the treatment of urinary stones. Accordingly, cavitation phenomenon and its basic concepts are presented in Section II. The significance of the ultrasound cavitation in the urinary stone treatment is discussed in Section III in detail and hydrodynamic cavitation as an important alternative for the ultrasound cavitation is included in Section IV. Finally, side effects of using both ultrasound and hydrodynamic cavitation in biomedical applications are presented in Section V.
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Cho KS, Jung HD, Ham WS, Chung DY, Kang YJ, Jang WS, Kwon JK, Choi YD, Lee JY. Optimal Skin-to-Stone Distance Is a Positive Predictor for Successful Outcomes in Upper Ureter Calculi following Extracorporeal Shock Wave Lithotripsy: A Bayesian Model Averaging Approach. PLoS One 2015; 10:e0144912. [PMID: 26659086 PMCID: PMC4699456 DOI: 10.1371/journal.pone.0144912] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 11/25/2015] [Indexed: 11/19/2022] Open
Abstract
Objectives To investigate whether skin-to-stone distance (SSD), which remains controversial in patients with ureter stones, can be a predicting factor for one session success following extracorporeal shock wave lithotripsy (ESWL) in patients with upper ureter stones. Patients and Methods We retrospectively reviewed the medical records of 1,519 patients who underwent their first ESWL between January 2005 and December 2013. Among these patients, 492 had upper ureter stones that measured 4–20 mm and were eligible for our analyses. Maximal stone length, mean stone density (HU), and SSD were determined on pretreatment non-contrast computed tomography (NCCT). For subgroup analyses, patients were divided into four groups. Group 1 consisted of patients with SSD<25th percentile, group 2 consisted of patients with SSD in the 25th to 50th percentile, group 3 patients had SSD in the 50th to 75th percentile, and group 4 patients had SSD≥75th percentile. Results In analyses of group 2 patients versus others, there were no statistical differences in mean age, stone length and density. However, the one session success rate in group 2 was higher than other groups (77.9% vs. 67.0%; P = 0.032). The multivariate logistic regression model revealed that shorter stone length, lower stone density, and the group 2 SSD were positive predictors for successful outcomes in ESWL. Using the Bayesian model-averaging approach, longer stone length, lower stone density, and group 2 SSD can be also positive predictors for successful outcomes following ESWL. Conclusions Our data indicate that a group 2 SSD of approximately 10 cm is a positive predictor for success following ESWL.
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Affiliation(s)
- Kang Su Cho
- Department of Urology, Gangnam Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Hae Do Jung
- Department of Urology, Incheon Red Cross Hospital, Incheon, Korea
| | - Won Sik Ham
- Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Doo Yong Chung
- Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Yong Jin Kang
- Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Won Sik Jang
- Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Jong Kyou Kwon
- Department of Urology, Severance Check-Up, Yonsei University Health System, Seoul, Korea
| | - Young Deuk Choi
- Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Joo Yong Lee
- Department of Urology, Severance Hospital, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea
- * E-mail:
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Ng CF, Luke S, Chiu PKF, Teoh JYC, Wong KT, Hou SSM. The effect of renal cortical thickness on the treatment outcomes of kidney stones treated with shockwave lithotripsy. Korean J Urol 2015; 56:379-85. [PMID: 25964839 PMCID: PMC4426510 DOI: 10.4111/kju.2015.56.5.379] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 04/04/2015] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Because the shock wave passes through various body tissues before reaching the stone, stone composition may affect the treatment efficacy of shock wave lithotripsy (SWL). We investigated the effect of various tissue components along the shock wave path on the success of SWL. MATERIALS AND METHODS From October 2008 to August 2010, a total of 206 patients with kidney stones sized 5 to 20 mm were prospectively recruited for a study of the factors that affect the outcome of treatment with a Sonolith Vision lithotripter. Successful SWL was defined as either stone-free status or residual fragments <4 mm at 12 weeks. Logistic regression analysis was performed to assess the factors that predicted treatment outcomes. Potential predictors included the patient's age, shock wave delivery rate, stone volume (SV), mean stone density (MSD), skin-to-stone distance (SSD), and the mean thickness of the three main components along the shock wave path: renal cortical thickness (KT), muscle thickness (MT), and soft-tissue thickness (ST). RESULTS The mean age of the patients was 53.8 years (range, 25-82 years). The overall treatment success rate after one session of SWL was 43.2%. The mean KT, MT, and ST were 26.9, 16.6, and 40.8 mm, respectively. The logistic regression results showed that a slower shock wave delivery rate, smaller SV, a lower MSD, and a thicker KT were found to be significant predictors for successful SWL. SSD, MT, and ST were not predictors of successful treatment. CONCLUSIONS Among the main tissue components along the shock wave path, a thicker KT was a favorable factor for successful SWL after adjustment for SV, MSD, and the shock wave delivery rate.
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Affiliation(s)
- Chi-Fai Ng
- The S.H. Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
| | - Sylvia Luke
- The S.H. Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
| | - Peter K F Chiu
- The S.H. Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
| | - Jeremy Y C Teoh
- The S.H. Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
| | - Ka-Tak Wong
- Department of Imaging and Intervention Radiology, The Chinese University of Hong Kong, Hong Kong, China
| | - Simon S M Hou
- The S.H. Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
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In vivo effects of focused shock waves on tumor tissue visualized by fluorescence staining techniques. Bioelectrochemistry 2014; 103:103-10. [PMID: 25200989 DOI: 10.1016/j.bioelechem.2014.08.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 08/13/2014] [Accepted: 08/18/2014] [Indexed: 11/23/2022]
Abstract
Shock waves can cause significant cytotoxic effects in tumor cells and tissues both in vitro and in vivo. However, understanding the mechanisms of shock wave interaction with tissues is limited. We have studied in vivo effects of focused shock waves induced in the syngeneic sarcoma tumor model using the TUNEL assay, immunohistochemical detection of caspase-3 and hematoxylin-eosin staining. Shock waves were produced by a multichannel pulsed-electrohydraulic discharge generator with a cylindrical ceramic-coated electrode. In tumors treated with shock waves, a large area of damaged tissue was detected which was clearly differentiated from intact tissue. Localization and a cone-shaped region of tissue damage visualized by TUNEL reaction apparently correlated with the conical shape and direction of shock wave propagation determined by high-speed shadowgraphy. A strong TUNEL reaction of nuclei and nucleus fragments in tissue exposed to shock waves suggested apoptosis in this destroyed tumor area. However, specificity of the TUNEL technique to apoptotic cells is ambiguous and other apoptotic markers (caspase-3) that we used in our study did not confirmed this observation. Thus, the generated fragments of nuclei gave rise to a false TUNEL reaction not associated with apoptosis. Mechanical stress from high overpressure shock wave was likely the dominant pathway of tumor damage.
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12
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Li G, McAteer JA, Williams JC, Berwick ZC. Effect of the body wall on lithotripter shock waves. J Endourol 2013; 28:446-52. [PMID: 24308532 DOI: 10.1089/end.2013.0662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE Determine the influence of passage through the body wall on the properties of lithotripter shock waves (SWs) and the characteristics of the acoustic field of an electromagnetic lithotripter. METHODS Full-thickness ex vivo segments of pig abdominal wall were secured against the acoustic window of a test tank coupled to the lithotripter. A fiber-optic probe hydrophone was used to measure SW pressures, determine shock rise time, and map the acoustic field in the focal plane. RESULTS Peak positive pressure on axis was attenuated roughly proportional to tissue thickness-approximately 6% per cm. Irregularities in the tissue path affected the symmetry of SW focusing, shifting the maximum peak positive pressure laterally by as much as ∼2 mm. Within the time resolution of the hydrophone (7-15 ns), shock rise time was unchanged, measuring ∼17-21 ns with and without tissue present. Mapping of the field showed no effect of the body wall on focal width, regardless of thickness of the body wall. CONCLUSIONS Passage through the body wall has minimal effect on the characteristics of lithotripter SWs. Other than reducing pulse amplitude and having the potential to affect the symmetry of the focused wave, the body wall has little influence on the acoustic field. These findings help to validate laboratory assessment of lithotripter acoustic field and suggest that the properties of SWs in the body are much the same as have been measured in vitro.
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Affiliation(s)
- Guangyan Li
- 1 Department of Anatomy and Cell Biology, Indiana University School of Medicine , Indianapolis, Indiana
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Leighton TG, Turangan CK, Jamaluddin AR, Ball GJ, White PR. Prediction of far-field acoustic emissions from cavitation clouds during shock wave lithotripsy for development of a clinical device. Proc Math Phys Eng Sci 2013. [DOI: 10.1098/rspa.2012.0538] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study presents the key simulation and decision stage of a multi-disciplinary project to develop a hospital device for monitoring the effectiveness of kidney stone fragmentation by shock wave lithotripsy (SWL). The device analyses, in real time, the pressure fields detected by sensors placed on the patient's torso, fields generated by the interaction of the incident shock wave, cavitation, kidney stone and soft tissue. Earlier free-Lagrange simulations of those interactions were restricted (by limited computational resources) to computational domains within a few centimetres of the stone. Later studies estimated the far-field pressures generated when those interactions involved only single bubbles. This study extends the free-Lagrange method to quantify the bubble–bubble interaction as a function of their separation. This, in turn, allowed identification of the validity of using a model of non-interacting bubbles to obtain estimations of the far-field pressures from 1000 bubbles distributed within the focus of the SWL field. Up to this point in the multi-disciplinary project, the design of the clinical device had been led by the simulations. This study records the decision point when the project's direction had to be led by far more costly clinical trials instead of the relatively inexpensive simulations.
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Affiliation(s)
- T. G. Leighton
- Institute of Sound and Vibration Research, University of Southampton, Highfield, Southampton SO17 1BJ, UK
- Faculty of Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK
| | - C. K. Turangan
- Faculty of Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK
- Fluid Dynamics, Institute of High Performance Computing, Singapore 138632, Republic of Singapore
| | - A. R. Jamaluddin
- Faculty of Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK
| | - G. J. Ball
- Atomic Weapons Establishment, Aldermaston, Reading RG7 4PR, UK
| | - P. R. White
- Institute of Sound and Vibration Research, University of Southampton, Highfield, Southampton SO17 1BJ, UK
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Krimmel J, Colonius T, Tanguay M. Simulation of the effects of cavitation and anatomy in the shock path of model lithotripters. ACTA ACUST UNITED AC 2010; 38:505-18. [PMID: 21063697 DOI: 10.1007/s00240-010-0332-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 10/14/2010] [Indexed: 10/18/2022]
Abstract
We report on recent efforts to develop predictive models for the pressure and other flow variables in the focal region of shock wave lithotripters. Baseline simulations of three representative lithotripters (electrohydraulic, electromagnetic, and piezoelectric) compare favorably with in vitro experiments (in a water bath). We proceed to model and investigate how shock focusing is altered by the presence of material interfaces associated with different types of tissue encountered along the shock path, and by the presence of cavitation bubbles that are excited by tensile pressures associated with the focused shock wave. We use human anatomical data, but simplify the description by assuming that the tissue behaves as a fluid, and by assuming cylindrical symmetry along the shock path. Scattering by material interfaces is significant, and regions of high pressure amplitudes (both compressive and tensile) are generated almost 4 cm postfocus. Bubble dynamics generate secondary shocks whose strength depends on the density of bubbles and the pulse repetition frequency (PRF). At sufficiently large densities, the bubbles also attenuate the shock. Together with experimental evidence, the simulations suggest that high PRF may be counterproductive for stone comminution. Finally, we discuss how the lithotripter simulations can be used as input to more detailed physical models that attempt to characterize the mechanisms by which collapsing cavitation models erode stones, and by which shock waves and bubbles may damage tissue.
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Affiliation(s)
- Jeff Krimmel
- Mechanical Engineering, Division of Engineering and Applied Science, California Institute of Technology, 1200 E California Blvd MC 104-44, Pasadena, CA 91125, USA.
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15
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Shock wave therapy for femoral head necrosis—Pressure measurements inside the femoral head. J Biomech 2010; 43:2065-9. [DOI: 10.1016/j.jbiomech.2010.04.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 04/06/2010] [Accepted: 04/10/2010] [Indexed: 11/21/2022]
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16
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Bohris C, Bayer T, Gumpinger R. Ultrasound monitoring of kidney stone extracorporeal shockwave lithotripsy with an external transducer: does fatty tissue cause image distortions that affect stone comminution? J Endourol 2010; 24:81-8. [PMID: 19961334 DOI: 10.1089/end.2009.0158] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Ultrasound imaging, using either an inline or an external transducer, is a standard method for extracorporeal shockwave lithotripsy (SWL) monitoring. This study investigates whether image distortions caused by the low sound speed of fatty tissue could lead to incorrect stone positioning such that disintegration is affected. MATERIALS AND METHODS To define the accuracy needed for SWL monitoring, the dependency of fragmentation efficiency on the distance between stone center and SWL focus was examined by in vitro model stone tests. In a clinical study, 15 patients with kidney stones were treated with a Dornier Sigma FarSight. This lithotripter was equipped with both an inline and an external transducer. They were operated alternately to check for inconsistencies, which would indicate ultrasound image distortions. In addition, the ultrasound paths from the transducer to the SWL focus were analyzed for error estimation. RESULTS AND DISCUSSION In the model stone tests, the number of shock waves required for complete fragmentation doubled if the stone was about 7.5 to 10 mm off focus in lateral direction. In the clinical trial, the stone positions obtained from an inline and an external transducer coincided within a 5 mm range of tolerance, but that approach suffered from some practical difficulties, resulting in measurement imprecision. The sound path analysis showed that the lengths through fatty tissue were too short to result in significant image distortion. The body mass index (20-31 kg/m(2)) was representative, except for very obese patients. Additional confirmation of correct stone positioning could be achieved quite easily by looking for pixel movement in the B-mode image or employing Doppler hit/miss monitoring. CONCLUSION Within the study group, no image distortion caused by fatty tissue that could be clinically relevant for SWL was observed.
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Canney MS, Khokhlova VA, Bessonova OV, Bailey MR, Crum LA. Shock-induced heating and millisecond boiling in gels and tissue due to high intensity focused ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 2010; 36:250-67. [PMID: 20018433 PMCID: PMC2815111 DOI: 10.1016/j.ultrasmedbio.2009.09.010] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 09/10/2009] [Accepted: 09/18/2009] [Indexed: 05/05/2023]
Abstract
Nonlinear propagation causes high-intensity ultrasound waves to distort and generate higher harmonics, which are more readily absorbed and converted to heat than the fundamental frequency. Although such nonlinear effects have been investigated previously and found to not significantly alter high-intensity focused ultrasound (HIFU) treatments, two results reported here change this paradigm. One is that at clinically relevant intensity levels, HIFU waves not only become distorted but form shock waves in tissue. The other is that the generated shock waves heat the tissue to boiling in much less time than predicted for undistorted or weakly distorted waves. In this study, a 2-MHz HIFU source operating at peak intensities up to 25,000 W/cm(2) was used to heat transparent tissue-mimicking phantoms and ex vivo bovine liver samples. Initiation of boiling was detected using high-speed photography, a 20-MHz passive cavitation detector and fluctuation of the drive voltage at the HIFU source. The time to boil obtained experimentally was used to quantify heating rates and was compared with calculations using weak shock theory and the shock amplitudes obtained from nonlinear modeling and measurements with a fiber optic hydrophone. As observed experimentally and predicted by calculations, shocked focal waveforms produced boiling in as little as 3 ms and the time to initiate boiling was sensitive to small changes in HIFU output. Nonlinear heating as a result of shock waves is therefore important to HIFU, and clinicians should be aware of the potential for very rapid boiling because it alters treatments.
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Affiliation(s)
- Michael S Canney
- Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA.
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18
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Abstract
Shock wave lithotripsy (SWL) is the process of fragmentation of renal or ureteric stones by the use of repetitive shock waves generated outside the body and focused onto the stone. Following its introduction in 1980, SWL revolutionized the treatment of kidney stones by offering patients a non-invasive procedure. It is now seen as a mature technology and its use is perceived to be routine. It is noteworthy that, at the time of its introduction, there was a great effort to discover the mechanism(s) by which it works, and the type of sound field that is optimal. Although nearly three decades of subsequent research have increased the knowledge base significantly, the mechanisms are still controversial. Furthermore there is a growing body of evidence that SWL results in injury to the kidney which may have long-term side effects, such as new onset hypertension, although again there is much controversy within the field. Currently, use of lithotripsy is waning, particularly with the advent of minimally invasive ureteroscopic approaches. The goal here is to review the state of the art in SWL and to present the barriers and challenges that need to be addressed for SWL to deliver on its initial promise of a safe, effective, non-invasive treatment for kidney stones.
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Affiliation(s)
- T G Leighton
- Institute of Sound and Vibration Research, University of Southampton, Southampton, UK
| | - R O Cleveland
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts, USA
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Kreider W, Bailey MR, Ketterling JA. Beamwidth measurement of individual lithotripter shock waves. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2009; 125:1240-1245. [PMID: 19206897 PMCID: PMC2677365 DOI: 10.1121/1.3050272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 08/13/2008] [Accepted: 11/17/2008] [Indexed: 05/27/2023]
Abstract
New lithotripters with narrower foci and higher peak pressures than the original Dornier HM3 electrohydraulic lithotripter have proven to be less effective and less safe. Hence, accurate measurements of the focal characteristics of lithotripter shock waves are important. The current technique for measuring beamwidth requires a collection of single-point measurements over multiple shock waves, thereby introducing error as a result of any shock-to-shock variability. This work reports on the construction of a hydrophone array sensor and on array measurements of individual lithotripter shock waves. Beamwidths for an electrohydraulic lithotripter with a broad-focus HM3-style reflector and a narrow-focus modified reflector were measured using both new and worn electrodes as well as two different electrical charging potentials. The array measured the waveform, beamwidth, and focal location of individual shock waves. The HM3-style reflector produced repeatable focal waveforms and beam profiles at an 18 kV charging potential with new and worn electrodes. Corresponding measurements suggest a narrower beamwidth than reported previously from averaged point measurements acquired under the same conditions. In addition, a lack of consistency in the measured beam profiles at 23 kV underscores the value of measuring individual shock waves.
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Affiliation(s)
- Wayne Kreider
- Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle, Washington 98105, USA.
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20
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Muratore R, Akabas T, Muratore IB. High-intensity focused ultrasound ablation of ex vivo bovine achilles tendon. ULTRASOUND IN MEDICINE & BIOLOGY 2008; 34:2043-2050. [PMID: 18692293 DOI: 10.1016/j.ultrasmedbio.2008.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 03/31/2008] [Accepted: 05/17/2008] [Indexed: 05/26/2023]
Abstract
Small tears in tendons are a common occurrence in athletes and others involved in strenuous physical activity. Natural healing in damaged tendons can result in disordered regrowth of the underlying collagen matrix of the tendon. These disordered regions are weaker than surrounding ordered regions of normal tendon and are prone to re-injury. Multiple cycles of injury and repair can lead to chronic tendinosis. Current treatment options either are invasive or are relatively ineffective in tendinosis without calcifications. High-intensity focused ultrasound (HIFU) has the potential to treat tendinosis noninvasively. HIFU ablation of tendons is based on a currently-used surgical analog, viz., needle tenotomy. This study tested the ability of HIFU beams to ablate bovine tendons ex vivo. Two ex vivo animal models were employed: a bare bovine Achilles tendon (deep digital flexor) on an acoustically absorbent rubber pad, and a layered model (chicken breast proximal, bovine Achilles tendon central and a glass plate distal to the transducer). The bare-tendon model enables examination of lesion formation under simple, ideal conditions; the layered model enables detection of possible damage to intervening soft tissue and consideration of the possibly confounding effects of distal bone. In both models, the tissues were degassed in normal phosphate-buffered saline. The bare tendon was brought to 23 degrees C or 37 degrees C before insonification; the layered model was brought to 37 degrees C before insonification. The annular array therapy transducer had an outer diameter of 33 mm, a focal length of 35 mm and a 14-mm diameter central hole to admit a confocal diagnostic transducer. The therapy transducer was excited with a continuous sinusoidal wave at 5.25 MHz to produce nominal in situ intensities from 0.23-2.6 kW/cm(2). Insonification times varied from 2-10 s. The focus was set over the range from the proximal tendon surface to 7 mm deep. The angle of incidence ranged from 0 degrees (normal to the tissue surface) to 15 degrees . After insonification, tendons were dissected and photographed, and the dimensions of the lesions were measured. Transmission electron micrographs were obtained from treated and untreated tissue regions. Insonification produced lesions that mimicked the shape of the focal region. When lesions were produced below the proximal tendon surface, no apparent damage to overlying soft tissue was apparent. The low intensities and short durations required for consistent lesion formation, and the relative insensitivity of ablation to small variations in the angle of incidence, highlight the potential of HIFU as a noninvasive treatment option for chronic tendinosis.
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Affiliation(s)
- Robert Muratore
- Frederic L. Lizzi Center for Biomedical Engineering, Riverside Research Institute, New York, NY 10038-2609, USA.
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21
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Leighton TG, Fedele F, Coleman AJ, McCarthy C, Ryves S, Hurrell AM, De Stefano A, White PR. A passive acoustic device for real-time monitoring of the efficacy of shockwave lithotripsy treatment. ULTRASOUND IN MEDICINE & BIOLOGY 2008; 34:1651-65. [PMID: 18562085 DOI: 10.1016/j.ultrasmedbio.2008.03.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 02/24/2008] [Accepted: 03/10/2008] [Indexed: 05/22/2023]
Abstract
Extracorporeal shockwave lithotripsy (ESWL) is the preferred modality for the treatment of renal and ureteric stone disease. Currently X-ray or ultrasound B-scan imaging are used to locate the stone and to check that it remains targeted at the focus of the lithotripter during treatment. Neither imaging modality is particularly effective in allowing the efficacy of treatment to be judged during the treatment session. A new device is described that, when placed on the patient's skin, can passively monitor the acoustic signals that propagate through the body after each lithotripter shock, and which can provide useful information on the effectiveness of targeting. These acoustic time histories are analyzed in real time to extract the two main characteristic peak amplitudes (m(1) and m(2)) and the time between these peaks (t(c)). A set of rules based on the acoustic parameters was developed during a clinical study in which a complete set of acoustic and clinical data was obtained for 30 of the 118 subjects recruited. The rules, which complied with earlier computational fluid dynamics (CFD) modeling and in vitro tests, allow each shock to be classified as "effective" or "ineffective." These clinically-derived rules were then applied in a second clinical study in which complete datasets were obtained for 49 of the 85 subjects recruited. This second clinical study demonstrated almost perfect agreement (kappa = 0.94) between the number of successful treatments, defined as >50% fragmentation as determined by X-ray at the follow-up appointment, and a device-derived global treatment score, TS(0), a figure derived from the total number of effective shocks in any treatment. The acoustic system is shown to provide a test of the success of the treatment that has a sensitivity of 91.7% and a specificity of 100%. In addition to the predictive capability, the device provides valuable real-time feedback to the lithotripter operator by indicating the effectiveness of each shock, plus an indication TS(t) of the cumulative effectiveness of the shocks given so far in any treatment, and trends in key parameters. This feedback would allow targeting adjustments to be made during treatment. An example is given of its application to mistargeting because of respiration.
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Affiliation(s)
- T G Leighton
- Institute of Sound and Vibration Research, University of Southampton, Southampton, UK
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Kidney damage in extracorporeal shock wave lithotripsy: a numerical approach for different shock profiles. Biomech Model Mechanobiol 2008; 8:285-99. [PMID: 18807077 DOI: 10.1007/s10237-008-0135-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Accepted: 07/26/2008] [Indexed: 10/21/2022]
Abstract
In shock-wave lithotripsy--a medical procedure to fragment kidney stones--the patient is subjected to hypersonic waves focused at the kidney stone. Although this procedure is widely applied, the physics behind this medical treatment, in particular the question of how the injuries to the surrounding kidney tissue arise, is still under investigation. To contribute to the solution of this problem, two- and three-dimensional numerical simulations of a human kidney under shock-wave loading are presented. For this purpose a constitutive model of the bio-mechanical system kidney is introduced, which is able to map large visco-elastic deformations and, in particular, material damage. The specific phenomena of cavitation induced oscillating bubbles is modeled here as an evolution of spherical pores within the soft kidney tissue. By means of large scale finite element simulations, we study the shock-wave propagation into the kidney tissue, adapt unknown material parameters and analyze the resulting stress states. The simulations predict localized damage in the human kidney in the same regions as observed in animal experiments. Furthermore, the numerical results suggest that in first instance the pressure amplitude of the shock wave impulse (and not so much its exact time-pressure profile) is responsible for damaging the kidney tissue.
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Abstract
With the introduction of the Dornier HM3 lithotripter, the successful history of extracorporeal shock wave lithotripsy (ESWL) for noninvasive treatment of urinary stones began about 25 years ago. The development of newer lithotripters has not been able to improve clinical efficacy because the shock wave parameters specifically responsible for stone disintegration or tissue trauma and pain induction have not yet been identified. Actual research in lithotripter technology deals with modification of the focal point. The evolution of endoscopic procedures, ureterorenoscopy, and percutaneous nephrolithotomy took longer but was more successful in terms of clinical efficacy. Nowadays, ESWL or an endoscopic procedure is offered as a reasonable option for most urinary stone cases. Therefore, economic aspects and the surgeon's expertise will become greater factors when a procedure is chosen. ESWL, with or without anaesthesia, will be an inherent part of future treatment modalities for urinary stones.
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Church CC, Carstensen EL, Nyborg WL, Carson PL, Frizzell LA, Bailey MR. The risk of exposure to diagnostic ultrasound in postnatal subjects: nonthermal mechanisms. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2008; 27:565-596. [PMID: 18359909 DOI: 10.7863/jum.2008.27.4.565] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This review examines the nonthermal physical mechanisms by which ultrasound can harm tissue in postnatal patients. First the physical nature of the more significant interactions between ultrasound and tissue is described, followed by an examination of the existing literature with particular emphasis on the pressure thresholds for potential adverse effects. The interaction of ultrasonic fields with tissue depends in a fundamental way on whether the tissue naturally contains undissolved gas under normal physiologic conditions. Examples of gas-containing tissues are lung and intestine. Considerable effort has been devoted to investigating the acoustic parameters relevant to the threshold and extent of lung hemorrhage. Thresholds as low as 0.4 MPa at 1 MHz have been reported. The situation for intestinal damage is similar, although the threshold appears to be somewhat higher. For other tissues, auditory stimulation or tactile perception may occur, if rarely, during exposure to diagnostic ultrasound; ultrasound at similar or lower intensities is used therapeutically to accelerate the healing of bone fractures. At the exposure levels used in diagnostic ultrasound, there is no consistent evidence for adverse effects in tissues that are not known to contain stabilized gas bodies. Although modest tissue damage may occur in certain identifiable applications, the risk for induction of an adverse biological effect by a nonthermal mechanism due to exposure to diagnostic ultrasound is extremely small.
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Affiliation(s)
- Charles C Church
- National Center for Physical Acoustics, University of Mississippi, 1 Coliseum Dr, University, MS 38677 USA.
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Pinton GF, Trahey GE. Modeling of shock wave propagation in large amplitude ultrasound. ULTRASONIC IMAGING 2008; 30:44-60. [PMID: 18564596 DOI: 10.1177/016173460803000106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The Rankine-Hugoniot relation for shock wave propagation describes the shock speed of a nonlinear wave. This paper investigates time-domain numerical methods that solve the nonlinear parabolic wave equation, or the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation, and the conditions they require to satisfy the Rankine-Hugoniot relation. Two numerical methods commonly used in hyperbolic conservation laws are adapted to solve the KZK equation: Godunov's method and the monotonic upwind scheme for conservation laws (MUSCL). It is shown that they satisfy the Rankine-Hugoniot relation regardless of attenuation. These two methods are compared with the current implicit solution based method. When the attenuation is small, such as in water, the current method requires a degree of grid refinement that is computationally impractical. All three numerical methods are compared in simulations for lithotripters and high intensity focused ultrasound (HIFU) where the attenuation is small compared to the nonlinearity because much of the propagation occurs in water. The simulations are performed on grid sizes that are consistent with present-day computational resources but are not sufficiently refined for the current method to satisfy the Rankine-Hugoniot condition. It is shown that satisfying the Rankine-Hugoniot conditions has a significant impact on metrics relevant to lithotripsy (such as peak pressures) and HIFU (intensity). Because the Godunov and MUSCL schemes satisfy the Rankine-Hugoniot conditions on coarse grids, they are particularly advantageous for three-dimensional simulations.
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Affiliation(s)
- Gianmarco F Pinton
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
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Tischer T, Milz S, Weiler C, Pautke C, Hausdorf J, Schmitz C, Maier M. Dose-Dependent New Bone Formation by Extracorporeal Shock Wave Application on the Intact Femur of Rabbits. Eur Surg Res 2008; 41:44-53. [DOI: 10.1159/000128279] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Accepted: 12/11/2007] [Indexed: 12/23/2022]
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Sapozhnikov OA, Maxwell AD, MacConaghy B, Bailey MR. A mechanistic analysis of stone fracture in lithotripsy. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2007; 121:1190-202. [PMID: 17348540 DOI: 10.1121/1.2404894] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
In vitro experiments and an elastic wave model were used to analyze how stress is induced in kidney stones by lithotripsy and to test the roles of individual mechanisms-spallation, squeezing, and cavitation. Cylindrical U30 cement stones were treated in an HM-3-style lithotripter. Baffles were used to block specific waves responsible for spallation or squeezing. Stones with and without surface cracks added to simulate cavitation damage were tested in glycerol (a cavitation suppressive medium). Each case was simulated using the elasticity equations for an isotropic medium. The calculated location of maximum stress compared well with the experimental observations of where stones fractured in two pieces. Higher calculated maximum tensile stress correlated with fewer shock waves required for fracture. The highest calculated tensile stresses resulted from shear waves initiated at the proximal corners and strengthened along the side surfaces of the stone by the liquid-borne lithotripter shock wave. Peak tensile stress was in the distal end of the stone where fracture occurred. Reflection of the longitudinal wave from the distal face of the stone--spallation-produced lower stresses. Surface cracks accelerated fragmentation when created near the location where the maximum stress was predicted.
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Affiliation(s)
- Oleg A Sapozhnikov
- Department of Acoustics, Physics Faculty, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
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Connors BA, Evan AP, Blomgren PM, Willis LR, Handa RK, Lifshitz DA, Lingeman JE, Ying J. Reducing shock number dramatically decreases lesion size in a juvenile kidney model. J Endourol 2007; 20:607-11. [PMID: 16999608 DOI: 10.1089/end.2006.20.607] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Adult stone patients are treated with several thousand lithotripter shockwaves (SWs) in order to pulverize a kidney stone. This typical clinical dose assures that the stone will be fractured completely. However, this same dose induces damage to the kidney, especially pediatric-size kidneys. If increasing SW number is known to increase renal injury and functional impairment, will reducing SW number below typical treatment levels significantly decrease kidney damage and hemodynamic changes? MATERIALS AND METHODS To address this question, one kidney in each of nine juvenile pigs (6-7 weeks old) was treated with 1000 SWs at 24 kV directed at a lower-pole calix with an unmodified HM-3 lithotripter. Parenchymal-lesion size was determined by sectioning the entire kidney and quantitating the amount of hemorrhage in each slice. Renal function was determined before and after SW treatment by inulin clearance, paraaminohippurate (PAH) extraction, and PAH clearance. The resulting morphologic and functional changes were then compared with those of kidneys that had been treated with a typical clinical dose of 2000 SWs (data previously published; J Am Soc Nephrol 2000;11:310). Eleven pigs were utilized as sham-treated controls. RESULTS Limiting SW number to 1000 significantly reduced the size of the lesion (by 95%) and reduced the degree of functional change (glomerular filtration rate by 38%, PAH extraction by 73%, renal plasma flow by 46%) compared with kidneys receiving 2000 SWs (an adult dose). CONCLUSIONS These data support the idea that SW number should be reduced to the lowest number that fractures kidney stones in order to minimize renal injury and functional impairment.
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Affiliation(s)
- Bret A Connors
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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Zhou Y, Zhong P. The effect of reflector geometry on the acoustic field and bubble dynamics produced by an electrohydraulic shock wave lithotripter. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2006; 119:3625-36. [PMID: 16838506 PMCID: PMC1994997 DOI: 10.1121/1.2195074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
A theoretical model for the propagation of shock wave from an axisymmetric reflector was developed by modifying the initial conditions for the conventional solution of a nonlinear parabolic wave equation (i.e., the Khokhlov-Zabolotskaya-Kuznestsov equation). The ellipsoidal reflector of an HM-3 lithotripter is modeled equivalently as a self-focusing spherically distributed pressure source. The pressure wave form generated by the spark discharge of the HM-3 electrode was measured by a fiber optic probe hydrophone and used as source conditions in the numerical calculation. The simulated pressure wave forms, accounting for the effects of diffraction, nonlinearity, and thermoviscous absorption in wave propagation and focusing, were compared with the measured results and a reasonably good agreement was found. Furthermore, the primary characteristics in the pressure wave forms produced by different reflector geometries, such as that produced by a reflector insert, can also be predicted by this model. It is interesting to note that when the interpulse delay time calculated by linear geometric model is less than about 1.5 micros, two pulses from the reflector insert and the uncovered bottom of the original HM-3 reflector will merge together. Coupling the simulated pressure wave form with the Gilmore model was carried out to evaluate the effect of reflector geometry on resultant bubble dynamics in a lithotripter field. Altogether, the equivalent reflector model was found to provide a useful tool for the prediction of pressure wave form generated in a lithotripter field. This model may be used to guide the design optimization of reflector geometries for improving the performance and safety of clinical lithotripters.
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Affiliation(s)
- Yufeng Zhou
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA.
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Cleveland RO, Sapozhnikov OA. Modeling elastic wave propagation in kidney stones with application to shock wave lithotripsy. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2005; 118:2667-76. [PMID: 16266186 DOI: 10.1121/1.2032187] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A time-domain finite-difference solution to the equations of linear elasticity was used to model the propagation of lithotripsy waves in kidney stones. The model was used to determine the loading on the stone (principal stresses and strains and maximum shear stresses and strains) due to the impact of lithotripsy shock waves. The simulations show that the peak loading induced in kidney stones is generated by constructive interference from shear waves launched from the outer edge of the stone with other waves in the stone. Notably the shear wave induced loads were significantly larger than the loads generated by the classic Hopkinson or spall effect. For simulations where the diameter of the focal spot of the lithotripter was smaller than that of the stone the loading decreased by more than 50%. The constructive interference was also sensitive to shock rise time and it was found that the peak tensile stress reduced by 30% as rise time increased from 25 to 150 ns. These results demonstrate that shear waves likely play a critical role in stone comminution and that lithotripters with large focal widths and short rise times should be effective at generating high stresses inside kidney stones.
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Affiliation(s)
- Robin O Cleveland
- Department of Aerospace and Mechanical Engineering, Boston University, 110 Cummington Street, Boston, Massachusetts 02215, USA.
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Bailey MR, Pishchalnikov YA, Sapozhnikov OA, Cleveland RO, McAteer JA, Miller NA, Pishchalnikova IV, Connors BA, Crum LA, Evan AP. Cavitation detection during shock-wave lithotripsy. ULTRASOUND IN MEDICINE & BIOLOGY 2005; 31:1245-56. [PMID: 16176791 DOI: 10.1016/j.ultrasmedbio.2005.02.017] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Revised: 02/17/2005] [Accepted: 02/25/2005] [Indexed: 05/04/2023]
Abstract
A system was built to detect cavitation in pig kidney during shock-wave lithotripsy (SWL) with a Dornier HM3 lithotripter. Active detection using echo on B-mode ultrasound, and passive cavitation detection using coincident signals on confocal orthogonal receivers, were used to interrogate the renal collecting system (urine) and the kidney parenchyma (tissue). Cavitation was detected in urine immediately upon shock-wave (SW) administration in urine or urine plus X-ray contrast agent but, in native tissue, cavitation required hundreds of SWs to initiate. Localization of cavitation was confirmed by fluoroscopy, sonography and by thermally marking the kidney using the passive cavitation detection receivers as high-intensity focused ultrasound sources. Cavitation collapse times in tissue and native urine were about the same, but less than in urine after injection of X-ray contrast agent. The finding that cavitation occurs in kidney tissue is a critical step toward determining the mechanisms of tissue injury in SWL.
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Affiliation(s)
- Michael R Bailey
- Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA.
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Harris GR. Progress in medical ultrasound exposimetry. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2005; 52:717-36. [PMID: 16048175 DOI: 10.1109/tuffc.2005.1503960] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Biomedical applications of ultrasound have experienced tremendous growth over the past 50 years. Early work in thermal therapy and surgery soon was followed by diagnostic imaging and Doppler. Because patient safety was an important issue from the beginning, the study of methods for measuring exposure levels, and their relationship to possible biological effects, paralleled the growth of the various therapeutic and diagnostic techniques. The diverse conditions of use have presented a range of exposure measurement challenges, and the sensors and techniques used to evaluate ultrasound fields have had to evolve as new or expanded clinical applications have emerged. In this paper some of the more notable of these developments are presented and discussed. Topics covered include devices and techniques, methods of calibration, progress in standardization, and current problem areas, including the effects of nonlinear propagation. Some early methods are described, but emphasis is given to more recent work applicable to present and future uses of ultrasound in medicine and biology.
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Affiliation(s)
- Gerald R Harris
- Food and Drug Administration, Center for Devices and Radiological Health, Rockville, MD 20850, USA.
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Shao Y, Connors BA, Evan AP, Willis LR, Lifshitz DA, Lingeman JE. Morphological changes induced in the pig kidney by extracorporeal shock wave lithotripsy: nephron injury. ACTA ACUST UNITED AC 2004; 275:979-89. [PMID: 14533172 DOI: 10.1002/ar.a.10115] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
While shock wave lithotripsy (SWL) is known to cause significant damage to the kidney, little is known about the initial injury to cells along the nephron. In this study, one kidney in each of six juvenile pigs (6-7 weeks old) was treated with 1,000 shock waves (at 24 kV) directed at a lower pole calyx with an unmodified HM-3 lithotripter. Three pigs were utilized as sham-controls. Kidneys were fixed by vascular perfusion immediately after SWL or sham-SWL. Three of the treated kidneys were used to quantitate lesion size. Cortical and medullary samples for light (LM) and transmission electron microscopy (TEM) were taken from the focal zone for the shock waves (F2), the contralateral kidney, and the kidneys of sham-SWL pigs. Because preservation of the tissue occurred within minutes of SWL, the initial injury caused by the shock waves could be separated from secondary changes. No tissue damage was observed in contralateral sham-SWL kidneys, but treated kidneys showed signs of injury, with a lesion of 0.2% +/- 0.1% of renal volume. Intraparenchymal hemorrhage and injury to tubules was found at F2 in both the cortex and medulla of SWL-treated kidneys. Tubular injury was always associated with intraparenchymal bleeding, and the range of tissue injury included total destruction of tubules, focal cellular fragmentation, necrosis, cell vacuolization, and membrane blebbing. The initial injury caused by SWL was cellular fragmentation and necrosis. Cellular vacuolization, membrane blebbing, and disorganization of apical brush borders appear to be secondary changes related to hypoxia.
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Affiliation(s)
- Youzhi Shao
- Department of Histology, Jinzhou Medical College, Jinzhou, Liaoning Province, People's Republic of China
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Zhou Y, Zhong P. Suppression of large intraluminal bubble expansion in shock wave lithotripsy without compromising stone comminution: refinement of reflector geometry. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2003; 113:586-597. [PMID: 12558294 DOI: 10.1121/1.1528174] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Using the Hamilton model [Hamilton, J. Acoust. Soc. Am. 93, 1256-1266 (1993)], the effects of reflector geometry on the pulse profile and sequence of the shock waves produced by the original and upgraded reflector of an HM-3 lithotripter were evaluated qualitatively. Guided by this analysis, we have refined the geometry of the upgraded reflector to enhance its suppressive effect on intraluminal bubble expansion without compromising stone comminution in shock wave lithotripsy. Using the original HM-3 reflector at 20 kV, rupture of a standard vessel phantom made of cellulose hollow fiber (i.d. = 0.2 mm), in which degassed water seeded with ultrasound contrast agents was circulated, was produced at the lithotripter focus after about 30 shocks. In contrast, using the upgraded reflector at 24 kV no rupture of the vessel phantom could be produced within a 20-mm diameter around the lithotripter focus even after 200 shocks. On the other hand, stone comminution was comparable between the two reflector configurations, although slightly larger fragments were produced by the upgraded reflector. After 2000 shocks, stone comminution efficiency produced by the original HM-3 reflector at 20 kV is 97.15 +/- 1.92% (mean +/- SD), compared to 90.35 +/- 1.96% produced by the upgraded reflector at 24 kV (p<0.02). All together, it was found that the upgraded reflector could significantly reduce the propensity for vessel rupture in shock wave lithotripsy while maintaining satisfactory stone comminution.
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Affiliation(s)
- Yufeng Zhou
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
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Sokolov DL, Bailey MR, Crum LA, Blomgren PM, Connors BA, Evan AP. Prefocal alignment improves stone comminution in shockwave lithotripsy. J Endourol 2002; 16:709-15. [PMID: 12542872 DOI: 10.1089/08927790260472845] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The Dornier HM-3 machine continues to be one of the most effective lithotripters in use. However, tissue damage occurs in most, if not all, shockwave lithotripsy (SWL) treatments. Cavitation appears to contribute to desired stone comminution as well as to undesired tissue damage. Studies of cavitation in electrohydraulic shockwave lithotripters indicate that the greatest cavitation activity occurs, not at the geometric focus, F2, but at a site proximal to F2 by 1 to 3 cm. In clinical practice, however, stones are aligned with F2. MATERIALS AND METHODS In vitro stone comminution, hemolysis, and free-radical production were assessed along the focal axis, and pig kidneys treated with SWL in vivo were sectioned to determine the extent of hemorrhagic injury along the focal axis. Model gypsum stones received 200 shockwaves in vitro at 18 kV. RESULTS At F2, the average number of fragments >1.5 mm was 1.3 +/- 0.5, and the weight loss was 11.3 +/- 1.1%. At 2 cm from F2 (F2-2 cm), these values increased to 4 +/- 2.8 and 16.1 +/- 4.2%, respectively. Samples of 10% hematocrit blood were similarly exposed. Hemolysis was equivalent at F2-2 cm (14.7 +/- 2.3%) and F2 (15.2 +/- 3%) but decreased significantly at all other positions. Samples of iodine solution received 1500 shockwaves at 20 kV. Hydroxyl radical production was greatest at F2-2 cm (0.384 +/- 0.035 microM) and decreased significantly distal to this position. The volume of tissue injury in pig kidneys was greatest with prefocal shockwave exposure. CONCLUSION Stone comminution may be achieved more rapidly without greater tissue damage by a simple shift in stone alignment to F2-2 cm.
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Affiliation(s)
- Dahlia L Sokolov
- Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle 98105, USA
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Abstract
Shock waves are specific sound waves produced by shock-wave generators; the generators currently available have different physical properties and represent different technical solutions. The measurement of shock-wave pressure is necessary in laboratory settings to define the physical characteristics of a given shock-wave source. Under clinical conditions other variables, e.g. the stone-free rate or the percentage of complications, are used to describe the efficacy and safety of a lithotripter.
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Affiliation(s)
- D M Wilbert
- Department of Urology, University of Tuebingen Medical School, Germany.
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Zhong P, Zhou Y. Suppression of large intraluminal bubble expansion in shock wave lithotripsy without compromising stone comminution: methodology and in vitro experiments. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2001; 110:3283-3291. [PMID: 11785829 DOI: 10.1121/1.1416906] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
To reduce the potential of vascular injury without compromising the stone comminution capability of a Dornier HM-3 lithotripter, we have devised a method to suppress intraluminal bubble expansion via in situ pulse superposition. A thin shell ellipsoidal reflector insert was designed and fabricated to fit snugly into the original reflector of an HM-3 lithotripter. The inner surface of the reflector insert shares the same first focus with the original HM-3 reflector, but has its second focus located 5 mm proximal to the generator than that of the HM-3 reflector. With this modification, the original lithotripter shock wave is partitioned into a leading lithotripter pulse (peak positive pressure of 46 MPa and positive pulse duration of 1 micros at 24 kV) and an ensuing second compressive wave of 10 MPa peak pressure and 2 micros pulse duration, separated from each other by about 4 micros. Superposition of the two waves leads to a selective truncation of the trailing tensile component of the lithotripter shock wave, and consequently, a reduction in the maximum bubble expansion up to 41% compared to that produced by the original reflector. The pulse amplitude and -6 dB beam width of the leading lithotripter shock wave from the upgraded reflector at 24 kV are comparable to that produced by the original HM-3 reflector at 20 kV. At the lithotripter focus, while only about 30 shocks are needed to cause a rupture of a blood vessel phantom made of cellulose hollow fiber (i.d.=0.2 mm) using the original HM-3 reflector at 20 kV, no rupture could be produced after 200 shocks using the upgraded reflector at 24 kV. On the other hand, after 100 shocks the upgraded reflector at 24 kV can achieve a stone comminution efficiency of 22%, which is better than the 18% efficiency produced by the original reflector at 20 kV (p = 0.043). All together, it has been shown in vitro that the upgraded reflector can produce satisfactory stone comminution while significantly reducing the potential for vessel rupture in shock wave lithotripsy.
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Affiliation(s)
- P Zhong
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA.
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Connors BA, Evan AP, Willis LR, Blomgren PM, Lingeman JE, Fineberg NS. The effect of discharge voltage on renal injury and impairment caused by lithotripsy in the pig. J Am Soc Nephrol 2000; 11:310-318. [PMID: 10665938 DOI: 10.1681/asn.v112310] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The present study was designed to determine the effects of shock wave voltage (kV) on lesion size and renal function induced by shock wave lithotripsy (SWL) in the 6- to 8-wk-old pig. Each SWL-treated pig received 2000 shock waves at 12, 18, or 24 kV to the lower pole calyx of one kidney. A group of sham SWL pigs served as time controls. Bilateral GFR, renal plasma flow (RPF), and para-aminohippurate (PAH) extraction were measured 1 h before and 1 and 4 h after SWL in all treated and sham animals. The kidneys were removed at the end of each experiment for morphometric analysis. The SWL-induced lesion increased significantly in size as shock wave energy was increased from 12 to 24 kV. PAH extraction, a measure of tubular function, was not significantly affected at 12 kV, was transiently reduced at 18 kV, and was reduced for the duration of the experiment at 24 kV. GFR and RPF, however, were significantly and similarly reduced at the 1 h post-SWL period at all three kilovolt levels. At the 4-h post-SWL period, both GFR and RPF had returned to baseline levels. Lesion size and tubular injury were correlated with changes in kilovoltage, while changes in renal hemodynamics were already maximal at the lowest discharge voltage. These findings suggest that renal microvessels are highly sensitive to shock waves and that frank injury to tubules and vessels may be more closely related to discharge energy than is renal blood flow.
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Affiliation(s)
- Bret A Connors
- Department of Anatomy, Indiana University School of Medicine, Indianapolis, Indiana
| | - Andrew P Evan
- Department of Anatomy, Indiana University School of Medicine, Indianapolis, Indiana
| | - Lynn R Willis
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Philip M Blomgren
- Department of Anatomy, Indiana University School of Medicine, Indianapolis, Indiana
| | - James E Lingeman
- Methodist Hospital Research Institute, Clarian Health Partners, Indianapolis, Indiana
| | - Naomi S Fineberg
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
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Harris GR, Preston RC, Dereggi AS. The impact of piezoelectric PVDF on medical ultrasound exposure measurements, standards, and regulations. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2000; 47:1321-35. [PMID: 18238678 DOI: 10.1109/58.883521] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This paper describes the development of PVDF hydrophones for characterizing medical ultrasound fields. The polymer hydrophone approaches that have resulted from this work are discussed, with emphasis given to the spot-poled membrane design that has become the de facto reference device for these measurements. The various national and international standards and regulations that have followed from the successful use of PVDF hydrophones also are summarized. The works discussed encompass polymer-based hydrophones designed primarily for diagnostic and lithotripsy exposure measurements, both in water and in vivo. The advent of these hydrophones has made possible accurate and reliable measurements of exposure levels encountered in medical ultrasound and, thus, has allowed questions of ultrasound bioeffects and device safety to be addressed in a consistent and scientifically sound manner.
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Affiliation(s)
- G R Harris
- Food and Drug Admin., Center for Devices and Radiological Health, Rockville, MD, USA
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Averkiou MA, Cleveland RO. Modeling of an electrohydraulic lithotripter with the KZK equation. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 1999; 106:102-12. [PMID: 10420620 DOI: 10.1121/1.427039] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The acoustic pressure field of an electrohydraulic extracorporeal shock wave lithotripter is modeled with a nonlinear parabolic wave equation (the KZK equation). The model accounts for diffraction, nonlinearity, and thermoviscous absorption. A numerical algorithm for solving the KZK equation in the time domain is used to model sound propagation from the mouth of the ellipsoidal reflector of the lithotripter. Propagation within the reflector is modeled with geometrical acoustics. It is shown that nonlinear distortion within the ellipsoidal reflector can play an important role for certain parameters. Calculated waveforms are compared with waveforms measured in a clinical lithotripter and good agreement is found. It is shown that the spatial location of the maximum negative pressure occurs pre-focally which suggests that the strongest cavitation activity will also be in front of the focus. Propagation of shock waves from a lithotripter with a pressure release reflector is considered and because of nonlinear propagation the focal waveform is not the inverse of the rigid reflector. Results from propagation through tissue are presented; waveforms are similar to those predicted in water except that the higher absorption in the tissue decreases the peak amplitude and lengthens the rise time of the shock.
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Affiliation(s)
- M A Averkiou
- Applied Physics Laboratory, University of Washington, Seattle 98105, USA
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