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Chen M, Neverova N, Xu S, Suwannaphoom K, Lluri G, Tamboline M, Duarte S, Fishbein MC, Luo Y, Packard RRS. Invasive electrochemical impedance spectroscopy with phase delay for experimental atherosclerosis phenotyping. FASEB J 2024; 38:e23700. [PMID: 38787606 DOI: 10.1096/fj.202302544rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 05/07/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024]
Abstract
Distinguishing quiescent from rupture-prone atherosclerotic lesions has significant translational and clinical implications. Electrochemical impedance spectroscopy (EIS) characterizes biological tissues by assessing impedance and phase delay responses to alternating current at multiple frequencies. We evaluated invasive 6-point stretchable EIS sensors over a spectrum of experimental atherosclerosis and compared results with intravascular ultrasound (IVUS), molecular positron emission tomography (PET) imaging, and histology. Male New Zealand White rabbits (n = 16) were placed on a high-fat diet, with or without endothelial denudation via balloon injury of the infrarenal abdominal aorta. Rabbits underwent in vivo micro-PET imaging of the abdominal aorta with 68Ga-DOTATATE, 18F-NaF, and 18F-FDG, followed by invasive interrogation via IVUS and EIS. Background signal-corrected values of impedance and phase delay were determined. Abdominal aortic samples were collected for histology. Analyses were performed blindly. EIS impedance was associated with markers of plaque activity including macrophage infiltration (r = .813, p = .008) and macrophage/smooth muscle cell (SMC) ratio (r = .813, p = .026). Moreover, EIS phase delay correlated with anatomic markers of plaque burden, namely intima/media ratio (r = .883, p = .004) and %stenosis (r = .901, p = .002), similar to IVUS. 68Ga-DOTATATE correlated with intimal macrophage infiltration (r = .861, p = .003) and macrophage/SMC ratio (r = .831, p = .021), 18F-NaF with SMC infiltration (r = -.842, p = .018), and 18F-FDG correlated with macrophage/SMC ratio (r = .787, p = .036). EIS with phase delay integrates key atherosclerosis features that otherwise require multiple complementary invasive and non-invasive imaging approaches to capture. These findings indicate the potential of invasive EIS to comprehensively evaluate human coronary artery disease.
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Affiliation(s)
- Michael Chen
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Natalia Neverova
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, USA
- Ronald Reagan UCLA Medical Center, Los Angeles, California, USA
- West Los Angeles Veterans Affairs Medical Center, Los Angeles, California, USA
| | - Shili Xu
- Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
- Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California, USA
| | - Krit Suwannaphoom
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Gentian Lluri
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, USA
- Ronald Reagan UCLA Medical Center, Los Angeles, California, USA
| | - Mikayla Tamboline
- Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Sandra Duarte
- Division of Laboratory and Animal Medicine, University of California, Los Angeles, California, USA
| | - Michael C Fishbein
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Yuan Luo
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, People's Republic of China
| | - René R Sevag Packard
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, USA
- Ronald Reagan UCLA Medical Center, Los Angeles, California, USA
- West Los Angeles Veterans Affairs Medical Center, Los Angeles, California, USA
- Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California, USA
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
- Department of Bioengineering, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, California, USA
- Molecular Biology Institute, University of California, Los Angeles, California, USA
- California NanoSystems Institute, University of California, Los Angeles, California, USA
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Chen M, Neverova N, Xu S, Suwannaphoom K, Lluri G, Tamboline M, Duarte S, Fishbein MC, Luo Y, Packard RRS. Flexible 3-D Electrochemical Impedance Spectroscopy Sensors Incorporating Phase Delay for Comprehensive Characterization of Atherosclerosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.20.558681. [PMID: 37786712 PMCID: PMC10541620 DOI: 10.1101/2023.09.20.558681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Background Distinguishing quiescent from rupture-prone atherosclerotic lesions has significant translational and clinical implications. Electrochemical impedance spectroscopy (EIS) characterizes biological tissues by assessing impedance and phase delay responses to alternating current at multiple frequencies.We evaluated invasive 6-point stretchable EIS sensors over a spectrum of experimental atherosclerosis and compared results with intravascular ultrasound (IVUS), molecular positron emission tomography (PET) imaging, and histology. Methods Male New Zealand White rabbits (n=16) were placed on a high-fat diet for 4 or 8 weeks, with or without endothelial denudation via balloon injury of the infrarenal abdominal aorta. Rabbits underwent in vivo micro-PET imaging of the abdominal aorta with 68 Ga-DOTATATE, 18 F-NaF, and 18 F-FDG, followed by invasive interrogation via IVUS and EIS. Background signal corrected values of impedance and phase delay were determined. Abdominal aortic samples were collected for histological analyses. Analyses were performed blindly. Results Phase delay correlated with anatomic markers of plaque burden, namely intima/media ratio (r=0.883 at 1 kHz, P =0.004) and %stenosis (r=0.901 at 0.25 kHz, P =0.002), similar to IVUS. Moreover, impedance was associated with markers of plaque activity including macrophage infiltration (r=0.813 at 10 kHz, P =0.008) and macrophage/smooth muscle cell (SMC) ratio (r=0.813 at 25 kHz, P =0.026). 68 Ga-DOTATATE correlated with intimal macrophage infiltration (r=0.861, P =0.003) and macrophage/SMC ratio (r=0.831, P =0.021), 18 F-NaF with SMC infiltration (r=-0.842, P =0.018), and 18 F-FDG correlated with macrophage/SMC ratio (r=0.787, P =0.036). Conclusions EIS with phase delay integrates key atherosclerosis features that otherwise require multiple complementary invasive and non-invasive imaging approaches to capture. These findings indicate the potential of invasive EIS as a comprehensive modality for evaluation of human coronary artery disease. GRAPHICAL ABSTRACT HIGHLIGHTS Electrochemical impedance spectroscopy (EIS) characterizes both anatomic features - via phase delay; and inflammatory activity - via impedance profiles, of underlying atherosclerosis.EIS can serve as an integrated, comprehensive metric for atherosclerosis evaluation by capturing morphological and compositional plaque characteristics that otherwise require multiple imaging modalities to obtain.Translation of these findings from animal models to human coronary artery disease may provide an additional strategy to help guide clinical management.
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Beatty R, Mendez KL, Schreiber LHJ, Tarpey R, Whyte W, Fan Y, Robinson ST, O'Dwyer J, Simpkin AJ, Tannian J, Dockery P, Dolan EB, Roche ET, Duffy GP. Soft robot-mediated autonomous adaptation to fibrotic capsule formation for improved drug delivery. Sci Robot 2023; 8:eabq4821. [PMID: 37647382 DOI: 10.1126/scirobotics.abq4821] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 08/02/2023] [Indexed: 09/01/2023]
Abstract
The foreign body response impedes the function and longevity of implantable drug delivery devices. As a dense fibrotic capsule forms, integration of the device with the host tissue becomes compromised, ultimately resulting in device seclusion and treatment failure. We present FibroSensing Dynamic Soft Reservoir (FSDSR), an implantable drug delivery device capable of monitoring fibrotic capsule formation and overcoming its effects via soft robotic actuations. Occlusion of the FSDSR porous membrane was monitored over 7 days in a rodent model using electrochemical impedance spectroscopy. The electrical resistance of the fibrotic capsule correlated to its increase in thickness and volume. Our FibroSensing membrane showed great sensitivity in detecting changes at the abiotic/biotic interface, such as collagen deposition and myofibroblast proliferation. The potential of the FSDSR to overcome fibrotic capsule formation and maintain constant drug dosing over time was demonstrated in silico and in vitro. Controlled closed loop release of methylene blue into agarose gels (with a comparable fold change in permeability relating to 7 and 28 days in vivo) was achieved by adjusting the magnitude and frequency of pneumatic actuations after impedance measurements by the FibroSensing membrane. By sensing fibrotic capsule formation in vivo, the FSDSR will be capable of probing and adapting to the foreign body response through dynamic actuation changes. Informed by real-time sensor signals, this device offers the potential for long-term efficacy and sustained drug dosing, even in the setting of fibrotic capsule formation.
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Affiliation(s)
- Rachel Beatty
- Anatomy and Regenerative Medicine Institute (REMEDI), School of Medicine, University of Galway, Galway, Ireland
- SFI Centre for Advanced Materials and BioEngineering Research (AMBER), Trinity College Dublin, Dublin, Ireland
| | - Keegan L Mendez
- Harvard-MIT Program in Health Sciences and Technology, Cambridge, MA, USA
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Lucien H J Schreiber
- Anatomy and Regenerative Medicine Institute (REMEDI), School of Medicine, University of Galway, Galway, Ireland
| | - Ruth Tarpey
- Anatomy and Regenerative Medicine Institute (REMEDI), School of Medicine, University of Galway, Galway, Ireland
- CÚRAM, Centre for Research in Medical Devices, University of Galway, Galway, Ireland
- Biomedical Engineering, School of Engineering, University of Galway, Galway, Ireland
| | - William Whyte
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Yiling Fan
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Scott T Robinson
- Anatomy and Regenerative Medicine Institute (REMEDI), School of Medicine, University of Galway, Galway, Ireland
- SFI Centre for Advanced Materials and BioEngineering Research (AMBER), Trinity College Dublin, Dublin, Ireland
| | - Joanne O'Dwyer
- Anatomy and Regenerative Medicine Institute (REMEDI), School of Medicine, University of Galway, Galway, Ireland
| | - Andrew J Simpkin
- School of Mathematical and Statistical Sciences, University of Galway, Galway, Ireland
| | - Joseph Tannian
- Anatomy and Regenerative Medicine Institute (REMEDI), School of Medicine, University of Galway, Galway, Ireland
| | - Peter Dockery
- Anatomy and Regenerative Medicine Institute (REMEDI), School of Medicine, University of Galway, Galway, Ireland
| | - Eimear B Dolan
- Anatomy and Regenerative Medicine Institute (REMEDI), School of Medicine, University of Galway, Galway, Ireland
- CÚRAM, Centre for Research in Medical Devices, University of Galway, Galway, Ireland
- Biomedical Engineering, School of Engineering, University of Galway, Galway, Ireland
| | - Ellen T Roche
- Harvard-MIT Program in Health Sciences and Technology, Cambridge, MA, USA
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Garry P Duffy
- Anatomy and Regenerative Medicine Institute (REMEDI), School of Medicine, University of Galway, Galway, Ireland
- SFI Centre for Advanced Materials and BioEngineering Research (AMBER), Trinity College Dublin, Dublin, Ireland
- CÚRAM, Centre for Research in Medical Devices, University of Galway, Galway, Ireland
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Boriesosdick J, Michael AE, Kröger JR, Niehoff JH, Saeed S, Pflug M, Schellinger P, Maus V, Borggrefe J, Mönninghoff C. Mechanical thrombectomy using the Nimbus stent-retriever - initial experiences in a single-center observational study. Interv Neuroradiol 2022:15910199221129097. [PMID: 36147011 DOI: 10.1177/15910199221129097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND The Nimbus stent-retriever (NSR) was developed for mechanical thrombectomy of wall-adherent thrombi in cerebral arteries. It features a novel geometry with a proximal spiral section and a distal barrel section. The new device is designed to retrieve tough clots with a micro-clamping technique. In the first case series reporting on the NSR, we share our initial experience about the first 12 treated cases. METHODS In total, 12 patients (5 men, 7 women; mean age 78 years) with occlusion of the internal carotid artery or the middle cerebral artery (M1 or M2 segment) were treated with the NSR, 11 after unsuccessful recanalization attempts with conventional stent-retrievers or aspiration thrombectomy. RESULTS Retrieving maneuvers with the NSR recovered a thrombus in 7 patients (58%), of which 6 resulted in vessel recanalization mTICI ≥ 2b. Successful recanalization improved the mTICI score by a median of 3 points. In 5 of 7 cases, this required only one thrombectomy maneuver. In 5 cases, no improvement of recanalization could be achieved with the NSR (1-3 attempts). No NSR-related complications occurred in this case series. CONCLUSIONS In our initial experience, the NSR appeared to be a safe and effective second-line stent-retriever after unsuccessful MT with conventional stent-retrievers or aspiration thrombectomy allowing for mTICI ≥ 2b rescue thrombectomy in ab 50% of cases. No NSR associated complications occurred in our case series.
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Affiliation(s)
- Jan Boriesosdick
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Arwed Elias Michael
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Jan-Robert Kröger
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Julius Henning Niehoff
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Saher Saeed
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Marc Pflug
- Department of Neurology and Neurogeriatrics, Johannes Wesling University Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Peter Schellinger
- Department of Neurology and Neurogeriatrics, Johannes Wesling University Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Volker Maus
- Department of Radiology, Neuroradiology and Nuclear Medicine, Knappschaftskrankenhaus Langendreer, Ruhr-University Bochum, Bochum, Germany
| | - Jan Borggrefe
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Christoph Mönninghoff
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr-University Bochum, Bochum, Germany
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
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Patil S, Darcourt J, Messina P, Bozsak F, Cognard C, Doyle K. Characterising acute ischaemic stroke thrombi: insights from histology, imaging and emerging impedance-based technologies. Stroke Vasc Neurol 2022; 7:353-363. [PMID: 35241632 PMCID: PMC9453827 DOI: 10.1136/svn-2021-001038] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 02/02/2022] [Indexed: 12/13/2022] Open
Abstract
Treatment of acute ischaemic stroke (AIS) focuses on rapid recanalisation of the occluded artery. In recent years, advent of mechanical thrombectomy devices and new procedures have accelerated the analysis of thrombi retrieved during the endovascular thrombectomy procedure. Despite ongoing developments and progress in AIS imaging techniques, it is not yet possible to conclude definitively regarding thrombus characteristics that could advise on the probable efficacy of thrombolysis or thrombectomy in advance of treatment. Intraprocedural devices with dignostic capabilities or new clinical imaging approaches are needed for better treatment of AIS patients. In this review, what is known about the composition of the thrombi that cause strokes and the evidence that thrombus composition has an impact on success of acute stroke treatment has been examined. This review also discusses the evidence that AIS thrombus composition varies with aetiology, questioning if suspected aetiology could be a useful indicator to stroke physicians to help decide the best acute course of treatment. Furthermore, this review discusses the evidence that current widely used radiological imaging tools can predict thrombus composition. Further use of new emerging technologies based on bioimpedance, as imaging modalities for diagnosing AIS and new medical device tools for detecting thrombus composition in situ has been introduced. Whether bioimpedance would be beneficial for gaining new insights into in situ thrombus composition that could guide choice of optimum treatment approach is also reviewed.
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Affiliation(s)
- Smita Patil
- CÚRAM, SFI Research Centre for Medical Devices, National University of Ireland Galway, Galway, Ireland
| | | | | | | | | | - Karen Doyle
- CÚRAM, SFI Research Centre for Medical Devices, National University of Ireland Galway, Galway, Ireland .,Physiology, National University of Ireland Galway, Galway, Ireland
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Oshin EA, Guo S, Jiang C. Determining tissue conductivity in tissue ablation by nanosecond pulsed electric fields. Bioelectrochemistry 2021; 143:107949. [PMID: 34583212 PMCID: PMC8643318 DOI: 10.1016/j.bioelechem.2021.107949] [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: 10/30/2020] [Revised: 09/10/2021] [Accepted: 09/15/2021] [Indexed: 02/03/2023]
Abstract
Nanosecond pulsed electric field (nsPEF) causes the permeabilization of the cell membrane and has been used to non-thermally treat cancerous tissues. As increased permeabilization in membranes were reported to be accompanied by impedance changes, the ablation effect of nsPEF on tissues can be monitored via the changes in tissue conductivity. In this study, effects of nsPEF on biological tissues were evaluated by determining the conductivities of potato and 4 T1-luc breast tumor tissues ex vivo from a murine model subjected to multiple 100-ns, 1-10 kV pulses. Using a four-needle electrode system with a calibrated electrode constant of 1.1 ± 0.1 cm, the conductivities of tissues was determined from both the network-analyzer measurement, before and after treatment, and voltage-current measurement in real-time. The conductivity of the potato tissue was measured for a frequency range of 0.1-3 MHz, and it increased with increasing pulse number and voltage amplitude. The conductivity of the tumor tissue was also observed to increase with pulse number and pulse voltage over a similar frequency range. In addition, the linear correlation between the ablation area in a treated potato tissue and the conductivity change in the tissue suggests that conductivity analysis of biological tissue under treatment could be a fast and sensitive approach to evaluate the effectiveness of a nsPEF treatment.
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Affiliation(s)
- Edwin A. Oshin
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA,Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, USA
| | - Siqi Guo
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA
| | - Chunqi Jiang
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, USA,Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, USA
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Kil SH, Kim GR, Lee MS, Kwak JH, Lim YH, Kim GD, Lee JK. Changes of electrical impedance characteristics with the radiation induced damage on biological tissue constituents. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2021; 29:383-395. [PMID: 33749628 DOI: 10.3233/xst-210840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This study analyzes the response of increasing radiation dose to the pork tenderloin tissue. Considering its significant cell structure, pork tenderloin tissue samples are selected for the experimental objects to measure their electrical impedance characteristics. This study proposes and investigates an effective approach to characterize the variation of the internal change of the components of pork tenderloin tissues caused by radiation. Changes in the pork tenderloin tissues are that the gap of the myotome is more far apart with increase of radiation dose because of the destroyed Myofibrils under the damage. With the increase of radiation dose, the impedance value of the pork tenderloin tissue decreases. Each of mean differences in the impedance values before and after irradiation dose under 1 Gy, 2 Gy and 4 Gy show 0.55±0.03, 1.09±0.14 and 1.97±0.14, respectively. However, the mean difference substantially increases to 13.08±0.16 at irradiation dose of 10 Gy. Thus, the cell membrane shows the most severe rupture at a radiation dose of 10 Gy. Changes in the microstructure of the irradiated pork tenderloin tissue samples are also checked and validated by a transmission electron microscope.
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Affiliation(s)
- Sang Hyeong Kil
- Department of Nuclear Medicine, Pusan National University Yang-san Hospital, Yang-san, Korea
| | - Gyeong Rip Kim
- Department of Neurosurgery, Pusan National University Yang-san Hospital, Yang-san, Korea
| | - Moo Seok Lee
- Department of Nuclear Medicine, Pusan National University Hospital, Busan, Korea
| | - Jong Hyeok Kwak
- Department of Radiology, Pusan National University Yang-san Hospital, Yangsan, Korea
| | - Yeong Hyeon Lim
- Department of Nuclear Medicine, Pusan National University Yang-san Hospital, Yang-san, Korea
| | - Gun Do Kim
- Department of Microbiology, Pukyong National University, Busan, Korea
| | - Jong Kyu Lee
- Department of Physics, Pukyong National University, Busan, Korea
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Luo Y, Abiri P, Zhang S, Chang CC, Kaboodrangi AH, Li R, Bui A, Kumar R, Woo M, Li Z, Packard RRS, Tai YC, Hsiai TK, Hsiai TK. Non-Invasive Electrical Impedance Tomography for Multi-Scale Detection of Liver Fat Content. Am J Cancer Res 2018; 8:1636-1647. [PMID: 29556346 PMCID: PMC5858172 DOI: 10.7150/thno.22233] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/01/2017] [Indexed: 12/12/2022] Open
Abstract
Introduction: Obesity is associated with an increased risk of nonalcoholic fatty liver disease (NAFLD). While Magnetic Resonance Imaging (MRI) is a non-invasive gold standard to detect fatty liver, we demonstrate a low-cost and portable electrical impedance tomography (EIT) approach with circumferential abdominal electrodes for liver conductivity measurements. Methods and Results: A finite element model (FEM) was established to simulate decremental liver conductivity in response to incremental liver lipid content. To validate the FEM simulation, we performed EIT imaging on an ex vivo porcine liver in a non-conductive tank with 32 circumferentially-embedded electrodes, demonstrating a high-resolution output given a priori information on location and geometry. To further examine EIT capacity in fatty liver detection, we performed EIT measurements in age- and gender-matched New Zealand White rabbits (3 on normal, 3 on high-fat diets). Liver conductivity values were significantly distinct following the high-fat diet (p = 0.003 vs. normal diet, n=3), accompanied by histopathological evidence of hepatic fat accumulation. We further assessed EIT imaging in human subjects with MRI quantification for fat volume fraction based on Dixon procedures, demonstrating average liver conductivity of 0.331 S/m for subjects with low Body-Mass Index (BMI < 25 kg/m²) and 0.286 S/m for high BMI (> 25 kg/m²). Conclusion: We provide both the theoretical and experimental framework for a multi-scale EIT strategy to detect liver lipid content. Our preliminary studies pave the way to enhance the spatial resolution of EIT as a marker for fatty liver disease and metabolic syndrome.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Tzung K Hsiai
- Department of Medical Engineering, California Institute of Technology, Pasadena, California.,Department of Bioengineering, Henry Samueli School of Engineering and Applied Sciences, University of California, Los Angeles, California.,Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
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Amini M, Hisdal J, Kalvøy H. Applications of Bioimpedance Measurement Techniques in Tissue Engineering. JOURNAL OF ELECTRICAL BIOIMPEDANCE 2018; 9:142-158. [PMID: 33584930 PMCID: PMC7852004 DOI: 10.2478/joeb-2018-0019] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Indexed: 05/19/2023]
Abstract
Rapid development in the field of tissue engineering necessitates implementation of monitoring methods for evaluation of the viability and characteristics of the cell cultures in a real-time, non-invasive and non-destructive manner. Current monitoring techniques are mainly histological and require labeling and involve destructive tests to characterize cell cultures. Bioimpedance measurement technique which benefits from measurement of electrical properties of the biological tissues, offers a non-invasive, label-free and real-time solution for monitoring tissue engineered constructs. This review outlines the fundamentals of bioimpedance, as well as electrical properties of the biological tissues, different types of cell culture constructs and possible electrode configuration set ups for performing bioimpedance measurements on these cell cultures. In addition, various bioimpedance measurement techniques and their applications in the field of tissue engineering are discussed.
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Affiliation(s)
- M. Amini
- Department of Physics, University of Oslo, Oslo, Norway
| | - J. Hisdal
- Vascular Investigations and Circulation lab, Aker Hospital, Oslo University Hospital, Oslo, Norway
| | - H. Kalvøy
- Department of Clinical and Biomedical Engineering, Rikshospitalet, Oslo University Hospital, Oslo, Norway
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Packard RRS, Luo Y, Abiri P, Jen N, Aksoy O, Suh WM, Tai YC, Hsiai TK. 3-D Electrochemical Impedance Spectroscopy Mapping of Arteries to Detect Metabolically Active but Angiographically Invisible Atherosclerotic Lesions. Am J Cancer Res 2017; 7:2431-2442. [PMID: 28744325 PMCID: PMC5525747 DOI: 10.7150/thno.19184] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 04/18/2017] [Indexed: 11/18/2022] Open
Abstract
We designed a novel 6-point electrochemical impedance spectroscopy (EIS) sensor with 15 combinations of permutations for the 3-D mapping and detection of metabolically active atherosclerotic lesions. Two rows of 3 stretchable electrodes circumferentially separated by 120° were mounted on an inflatable balloon for intravascular deployment and endoluminal interrogation. The configuration and 15 permutations of 2-point EIS electrodes allowed for deep arterial penetration via alternating current (AC) to detect varying degrees of lipid burden with distinct impedance profiles (Ω). By virtue of the distinctive impedimetric signature of metabolically active atherosclerotic lesions, a detailed impedance map was acquired, with the 15 EIS permutations uncovering early stages of disease characterized by fatty streak lipid accumulation in the New Zealand White rabbit model of atherosclerosis. Both the equivalent circuit and statistical analyses corroborated the 3-D EIS permutations to detect small, angiographically invisible, lipid-rich lesions, with translational implications for early atherosclerotic disease detection and prevention of acute coronary syndromes or strokes.
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Two-Point Stretchable Electrode Array for Endoluminal Electrochemical Impedance Spectroscopy Measurements of Lipid-Laden Atherosclerotic Plaques. Ann Biomed Eng 2016; 44:2695-706. [PMID: 26857007 DOI: 10.1007/s10439-016-1559-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 01/29/2016] [Indexed: 12/28/2022]
Abstract
Four-point electrode systems are commonly used for electric impedance measurements of biomaterials and tissues. We introduce a 2-point system to reduce electrode polarization for heterogeneous measurements of vascular wall. Presence of endoluminal oxidized low density lipoprotein (oxLDL) and lipids alters the electrochemical impedance that can be measured by electrochemical impedance spectroscopy (EIS). We developed a catheter-based 2-point micro-electrode configuration for intravascular deployment in New Zealand White rabbits. An array of 2 flexible round electrodes, 240 µm in diameter and separated by 400 µm was microfabricated and mounted on an inflatable balloon catheter for EIS measurement of the oxLDL-rich lesions developed as a result of high-fat diet-induced hyperlipidemia. Upon balloon inflation, the 2-point electrode array conformed to the arterial wall to allow deep intraplaque penetration via alternating current (AC). The frequency sweep from 10 to 300 kHz generated an increase in capacitance, providing distinct changes in both impedance (Ω) and phase (ϕ) in relation to varying degrees of intraplaque lipid burden in the aorta. Aortic endoluminal EIS measurements were compared with epicardial fat tissue and validated by intravascular ultrasound and immunohistochemistry for plaque lipids and foam cells. Thus, we demonstrate a new approach to quantify endoluminal EIS via a 2-point stretchable electrode strategy.
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Cao H, Yu F, Zhao Y, Scianmarello N, Lee J, Dai W, Jen N, Beebe T, Li R, Ebrahimi R, Chang DS, Mody FV, Pacella J, Tai YC, Hsiai T. Stretchable electrochemical impedance sensors for intravascular detection of lipid-rich lesions in New Zealand White rabbits. Biosens Bioelectron 2013; 54:610-6. [PMID: 24333932 DOI: 10.1016/j.bios.2013.11.059] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 11/12/2013] [Accepted: 11/20/2013] [Indexed: 12/31/2022]
Abstract
Flexible electronics have enabled catheter-based intravascular sensing. However, real-time interrogation of unstable plaque remains an unmet clinical challenge. Here, we demonstrate the feasibility of stretchable electrochemical impedance spectroscopy (EIS) sensors for endoluminal investigations in New Zealand White (NZW) rabbits on diet-induced hyperlipidemia. A parylene C (PAC)-based EIS sensor mounted on the surface of an inflatable silicone balloon affixed to the tip of an interrogating catheter was deployed (1) on the explants of NZW rabbit aorta for detection of lipid-rich atherosclerotic lesions, and (2) on live animals for demonstration of balloon inflation and EIS measurements. An input peak-to-peak AC voltage of 10 mV and sweeping-frequency from 300 kHz to 100 Hz were delivered to the endoluminal sites. Balloon inflation allowed EIS sensors to be in contact with endoluminal surface. In the oxidized low-density-lipoprotein (oxLDL)-rich lesions from explants of fat-fed rabbits, impedance magnitude increased significantly by 1.5-fold across the entire frequency band, and phase shifted ~5° at frequencies below 10 kHz. In the lesion-free sites of the normal diet-fed rabbits, impedance magnitude increased by 1.2-fold and phase shifted ~5° at frequencies above 30 kHz. Thus, we demonstrate the feasibility of stretchable intravascular EIS sensors for identification of lipid rich lesions, with a translational implication for detecting unstable lesions.
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Affiliation(s)
- Hung Cao
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States; Division of Cardiology, Department of Medicine, VA Greater Los Angeles Healthcare System, School of Medicine, University of California, United States
| | - Fei Yu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
| | - Yu Zhao
- Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Nick Scianmarello
- Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Juhyun Lee
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States; Division of Cardiology, Department of Medicine, VA Greater Los Angeles Healthcare System, School of Medicine, University of California, United States
| | - Wangde Dai
- The Heart Institute of Good Samaritan Hospital, Los Angeles, CA, United States
| | - Nelson Jen
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States; Division of Cardiology, Department of Medicine, VA Greater Los Angeles Healthcare System, School of Medicine, University of California, United States
| | - Tyler Beebe
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States; Division of Cardiology, Department of Medicine, VA Greater Los Angeles Healthcare System, School of Medicine, University of California, United States
| | - Rongsong Li
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States; Division of Cardiology, Department of Medicine, VA Greater Los Angeles Healthcare System, School of Medicine, University of California, United States
| | - Ramin Ebrahimi
- Division of Cardiology, Department of Medicine, VA Greater Los Angeles Healthcare System, School of Medicine, University of California, United States
| | - Donald S Chang
- Division of Cardiology, Department of Medicine, VA Greater Los Angeles Healthcare System, School of Medicine, University of California, United States
| | - Freny V Mody
- Division of Cardiology, Department of Medicine, VA Greater Los Angeles Healthcare System, School of Medicine, University of California, United States
| | - John Pacella
- Division of Cardiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Yu-Chong Tai
- Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Tzung Hsiai
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States; Division of Cardiology, Department of Medicine, VA Greater Los Angeles Healthcare System, School of Medicine, University of California, United States.
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Yu F, Lee J, Jen N, Li X, Zhang Q, Tang R, Zhou Q, Kim ES, Hsiai TK. Elevated electrochemical impedance in the endoluminal regions with high shear stress: implication for assessing lipid-rich atherosclerotic lesions. Biosens Bioelectron 2012; 43:237-44. [PMID: 23318546 DOI: 10.1016/j.bios.2012.12.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 11/29/2012] [Accepted: 12/04/2012] [Indexed: 12/19/2022]
Abstract
BACKGROUND Identifying metabolically active atherosclerotic lesions remains an unmet clinical challenge during coronary intervention. Electrochemical impedance (EIS) increased in response to oxidized low density lipoprotein (oxLDL)-laden lesions. We hereby assessed whether integrating EIS with intravascular ultrasound (IVUS) and shear stress (ISS) provided a new strategy to assess oxLDL-laden lesions in the fat-fed New Zealand White (NZW) rabbits. METHODS AND RESULTS A micro-heat transfer sensor was deployed to acquire the ISS profiles at baseline and post high-fat diet (HD) in the NZW rabbits (n=8). After 9 weeks of HD, serum oxLDL levels (mg/dL) increased by 140 fold, accompanied by a 1.5-fold increase in kinematic viscosity (cP) in the HD group. Time-averaged ISS (ISSave) in the thoracic aorta also increased in the HD group (baseline: 17.61±0.24 vs. 9 weeks: 25.22±0.95dyne/cm(2), n=4), but remained unchanged in the normal diet group (baseline: 22.85±0.53dyn/cm(2) vs. 9 weeks: 22.37±0.57dyne/cm(2), n=4). High-frequency intravascular ultrasound (IVUS) revealed atherosclerotic lesions in the regions with augmented ISSave, and concentric bipolar microelectrodes demonstrated elevated EIS signals, which were correlated with prominent anti-oxLDL immuno-staining (oxLDL-free regions: 497±55Ω, n=8 vs. oxLDL-rich lesions: 679±125Ω, n=12, P<0.05). The equivalent circuit model for tissue resistance between the lesion-free and ox-LDL-rich lesions further validated the experimental EIS signals. CONCLUSIONS By applying electrochemical impedance in conjunction with shear stress and high-frequency ultrasound sensors, we provided a new strategy to identify oxLDL-laden lesions. The study demonstrated the feasibility of integrating EIS, ISS, and IVUS for a catheter-based approach to assess mechanically unstable plaque.
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Affiliation(s)
- Fei Yu
- Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089, USA
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Streitner I, Goldhofer M, Cho S, Kinscherf R, Thielecke H, Borggrefe M, Süselbeck T, Streitner F. Cellular imaging of human atherosclerotic lesions by intravascular electric impedance spectroscopy. PLoS One 2012; 7:e35405. [PMID: 22509411 PMCID: PMC3324547 DOI: 10.1371/journal.pone.0035405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 03/15/2012] [Indexed: 11/30/2022] Open
Abstract
Background Newer techniques are required to identify atherosclerotic lesions that are prone to rupture. Electric impedance spectroscopy (EIS) is able to provide information about the cellular composition of biological tissue. The present study was performed to determine the influence of inflammatory processes in type Va (lipid core, thick fibrous cap) and Vc (abundant fibrous connective tissue while lipid is minimal or even absent) human atherosclerotic lesions on the electrical impedance of these lesions measured by EIS. Methods and Results EIS was performed on 1 aortic and 3 femoral human arteries at 25 spots with visually heavy plaque burden. Severely calcified lesions were excluded from analysis. A highly flexible micro-electrode mounted onto a balloon catheter was placed on marked regions to measure impedance values at 100 kHz. After paraffin embedding, visible marked cross sections (n = 21) were processed. Assessment of lesion types was performed by Movats staining. Immunostaining for CD31 (marker of neovascularisation), CD36 (scavenger cells) and MMP-3 (matrix metalloproteinase-3) was performed. The amount of positive cells was assessed semi-quantitatively. 15 type Va lesions and 6 type Vc lesions were identified. Lesions containing abundant CD36-, CD31- and MMP-3-positive staining revealed significantly higher impedance values compared to lesions with marginal or without positive staining (CD36+455±50 Ω vs. CD36- 346±53 Ω, p = 0.001; CD31+436±43 Ω vs. CD31- 340±55 Ω, p = 0.001; MMP-3+ 400±68 Ω vs. MMP-3- 323±33 Ω, p = 0.03). Conclusions Atherosclerotic lesions with abundant neovascularisation (CD31), many scavenger receptor class B expressing cells (CD36) or high amount of MMP-3 immunoreactivity reveal significantly higher impedance values compared to lesions with marginal or no detection of immunoreactivity. Findings suggest that inflammatory processes in vulnerable plaques affect the impedance of atherosclerotic lesions and might therefore be detected by EIS.
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Affiliation(s)
- Ines Streitner
- 1st Department of Medicine-Cardiology, University Medical Centre Mannheim, Mannheim, Germany.
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Yu F, Dai X, Beebe T, Hsiai T. Electrochemical impedance spectroscopy to characterize inflammatory atherosclerotic plaques. Biosens Bioelectron 2011; 30:165-73. [PMID: 21959227 PMCID: PMC3210389 DOI: 10.1016/j.bios.2011.09.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 09/09/2011] [Accepted: 09/09/2011] [Indexed: 11/28/2022]
Abstract
Despite advances in diagnosis and therapy, atherosclerotic cardiovascular disease remains the leading cause of morbidity and mortality in the Western world. Predicting metabolically active atherosclerotic lesions has remained an unmet clinical need. We hereby developed an electrochemical strategy to characterize the inflammatory states of high-risk atherosclerotic plaques. Using the concentric bipolar microelectrodes, we sought to demonstrate distinct Electrochemical Impedance Spectroscopic (EIS) measurements for unstable atherosclerotic plaques that harbored active lipids and inflammatory cells. Using equivalent circuits to simulate vessel impedance at the electrode-endoluminal tissue interface, we demonstrated specific electric elements to model working and counter electrode interfaces as well as the tissue impedance. Using explants of human coronary, carotid, and femoral arteries at various Stary stages of atherosclerotic lesions (n=15), we performed endoluminal EIS measurements (n=147) and validated with histology and immunohistochemistry. We computed the vascular tissue resistance using the equivalent circuit model and normalized the resistance to the lesion-free regions. Tissue resistance was significantly elevated in the oxLDL-rich thin-cap atheromas (1.57±0.40, n=14, p<0.001) and fatty streaks (1.36±0.28, n=33, p<0.001) as compared with lesion-free region (1.00±0.18, n=82) or oxLDL-absent fibrous atheromas (0.86±0.30, n=12). Tissue resistance was also elevated in the calcified core of fibrous atheroma (2.37±0.60, n=6, p<0.001). Despite presence of fibrous structures, tissue resistance between ox-LDL-absent fibroatheroma and the lesion-free regions was statistically insignificant (0.86±0.30, n=12, p>0.05). Hence, we demonstrate that the application of EIS strategy was sensitive to detect fibrous cap oxLDL-rich lesions and specific to distinguish oxLDL-absent fibroatheroma.
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Affiliation(s)
- Fei Yu
- Biomedical Engineering and Cardiovascular Medicine, University of Southern California, DRB Suite 140, 1042 Downey Way, Los Angeles, California, USA 90089
| | - Xiaohu Dai
- Biomedical Engineering and Cardiovascular Medicine, University of Southern California, DRB Suite 140, 1042 Downey Way, Los Angeles, California, USA 90089
| | - Tyler Beebe
- Biomedical Engineering and Cardiovascular Medicine, University of Southern California, DRB Suite 140, 1042 Downey Way, Los Angeles, California, USA 90089
| | - Tzung Hsiai
- Biomedical Engineering and Cardiovascular Medicine, University of Southern California, DRB Suite 140, 1042 Downey Way, Los Angeles, California, USA 90089
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Yu F, Li R, Ai L, Edington C, Yu H, Barr M, Kim ES, Hsiai TK. Electrochemical impedance spectroscopy to assess vascular oxidative stress. Ann Biomed Eng 2010; 39:287-96. [PMID: 20652746 DOI: 10.1007/s10439-010-0127-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Accepted: 07/09/2010] [Indexed: 10/19/2022]
Abstract
Vascular inflammatory responses are intimately linked with oxidative stress, favoring the development of pre-atherosclerotic lesions. We proposed that oxidized low density lipoprotein (oxLDL) and foam cell infiltrates in the subendothelial layer engendered distinct electrochemical properties that could be measured in terms of the electrochemical impedance spectroscopy (EIS). Concentric bipolar microelectrodes were applied to interrogate EIS of aortas isolated from fat-fed New Zealand White (NZW) rabbits and explants of human aortas. Frequency-dependent EIS measurements were assessed between 10 kHz and 100 kHz, and were significantly elevated in the pre-atherosclerotic lesions in which oxLDL and macrophage infiltrates were prevalent (At 100 kHz: aortic arch lesion=26.7±2.7 kΩ vs. control=15.8±2.4 kΩ; at 10 kHz: lesions=49.2±7.3 kΩ vs. control=27.6±2.7 kΩ, n=10, p<0.001). Similarly, EIS measurements were significantly elevated in the human descending aorta where pre-atherosclerotic lesions or fatty streaks were prominent. EIS measurements remained unchanged in spite of various depths of electrode submersion or orientation of the specimens. Hence, the concentric bipolar microelectrodes provided a reliable means to measure endoluminal electrochemical modifications in regions of pro-inflammatory with high spatial resolution and reproducibility albeit uneven lesion topography and non-uniform current distribution.
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Affiliation(s)
- Fei Yu
- Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089, USA
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Electric impedance spectroscopy of human atherosclerotic lesions. Atherosclerosis 2009; 206:464-8. [PMID: 19419719 DOI: 10.1016/j.atherosclerosis.2009.03.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 03/10/2009] [Accepted: 03/10/2009] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The aim of this in vitro study was to investigate the feasibility of a new highly flexible microelectrode on human tissue and its potential of differentiating atherosclerotic lesions by electric impedance spectroscopy (EIS). METHODS Electric impedance measurements (EIM) were performed on 148 spots of 7 aortic and 6 femoral human arteries at 1kHz, 10kHz and 100kHz. RESULTS According to the AHA classification 33 (25%) grade I lesions (PI), 34 (26%) grade II (PII), 21 (16%) grade III (PIII), 21 (16%) grade IV (PIV), 13 (10%) grade Va (PVa) and 10 (8%) grade Vb (PVb) could be identified by histology. At 1kHz, 10kHz and 100kHz the mean electric impedance (MEI) of PI, PII, PIII and PIV was statistically not different. At 100kHz the MEI of PVa showed significantly higher values compared to the MEI of PI (455+/-66Omega vs. 375+/-47Omega, p=0.05), PII (455+/-66Omega vs. 358+/-63Omega, p=0.007), PIII (455+/-66Omega vs. 342+/-52Omega, p=0.003), PIV (455+/-66Omega vs. 356+/-41Omegap=0.013) and the MEI of PVb was significantly increased compared to the MEI of PI (698+/-239Omega vs. 375+/-47Omega, p<0.001), PII (698+/-239Omega vs. 358+/-63Omegap<0.001), PIII (698+/-239Omega vs. 342+/-52Omegap<0.001), PIV (698+/-239Omega vs. 356+/-41Omegap<0.001), PVa (698+/-239Omega vs. 455+/-66Omega, p<0.001). Performing ROC analyses for the detection of grouped PVa/PVb lesions, the largest AUC was found at 100kHz with a cut-off value of 441Omega presenting a sensitivity of 74% and a specificity of 94%. CONCLUSIONS EIM could be performed on human aortic and femoral tissue. The results show that EIS has the potential to distinguish between different plaque types.
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Dean D, Ramanathan T, Machado D, Sundararajan R. Electrical Impedance Spectroscopy Study of Biological Tissues. JOURNAL OF ELECTROSTATICS 2008; 66:165-177. [PMID: 19255614 PMCID: PMC2597841 DOI: 10.1016/j.elstat.2007.11.005] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The objective of this study was to investigate the electrical impedance properties of rat lung and other tissues ex vivo using Electrical Impedance Spectroscopy. Rat lungs (both electroporated and naïve (untreated)), and mesenteric vessels (naïve) were harvested from male Sprague-Dawley rats; their electrical impedance were measured using a Solartron 1290 impedance analyzer. Mouse lung and heart samples (naïve) were also studied. The resistance (Real Z, ohm) and the reactance (Im Z, negative ohm)) magnitudes and hence the Cole-Cole (Real Z versus Im Z) plots are different for the electroporated lung and the naive lung. The results confirm the close relationship between the structure and the functional characteristic. These also vary for the different biological tissues studied. The impedance values were higher at low frequencies compared to those at high frequencies. This study is of practical interest for biological applications of electrical pulses, such as electroporation, whose efficacy depends on cell type and its electrical impedance characteristics.
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Affiliation(s)
- D.A. Dean
- Division of Pulmonary & Critical Care, Northwestern University Medical School, Chicago, IL-60611, e-mail:
| | - T. Ramanathan
- Mechanical Engineering Dept., Northwestern University, Evanston, IL-60208, e-mail:
| | - D. Machado
- Division of Pulmonary & Critical Care, Northwestern University Medical School, Chicago, IL-60611, e-mail:
| | - R. Sundararajan
- Division of Pulmonary & Critical Care, Northwestern University Medical School, Chicago, IL-60611, e-mail:
- Electronics & Computer Engineering Technology, Arizona State University, Mesa, AZ-85212
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Cho S, Thielecke H. Influence of electrode position on the characterization of artery stenotic plaques by using impedance catheter. IEEE Trans Biomed Eng 2006; 53:2401-4. [PMID: 17073347 DOI: 10.1109/tbme.2006.883616] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Use of balloon impedance catheters (BIC) for the characterization of plaques in vessels can support an optimal medical treatment of plaques. The sensitivity of impedance diagnoses with BIC is related with the distribution of electric fields determined by the electrode configuration. Using the three-dimensional finite element method (FEM) simulation, it was estimated how the relative positions of electrode array to the lipid in the vessel affect on the total impedance magnitude. Further, the short-circuiting effect was investigated with respect to the separation distance on the angular axis between the electrode arrays of angular set. By aid of FEM simulations, it is possible to design the sets of multielectrode arrays which have an optimized resolution for individual vessels.
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Affiliation(s)
- Sungbo Cho
- Biohybrid Systems Department, Fraunhofer Institute for Biomedical Engineering, Ensheimerstr. 48,66386 St. Ingbert, Germany.
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