101
|
McDermott B, Porter E, Jones M, McGinley B, O'Halloran M. Symmetry difference electrical impedance tomography-a novel modality for anomaly detection. Physiol Meas 2018. [PMID: 29533921 DOI: 10.1088/1361-6579/aab656] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The theoretical basis, experimental implementation, and proof of concept of a novel electrical impedance tomography (EIT) imaging technique, called symmetry difference EIT, is described. This technique is applicable in situations where there is inherent symmetry in the region being imaged. METHODS The sample scenario of the human head is used to describe the technique. The head is largely symmetrical across the sagittal plane. A unilateral lesion such as a haemorrhage or region of ischaemia distorts that symmetry. This distortion may be visualised using EIT. Measurement sets from a ring of electrodes placed on the boundary in both clockwise and counter-clockwise orientations are compared to detect the anomaly. Computer simulations featuring a hemispherical model of the head and brain are used initially to demonstrate the theory. Then, a more complex numerical model with anatomically accurate finite element models (FEMs) is used to expand on the concept with a more realistic scenario. Finally, tank experiments are performed with phantom lesions to validate the technique in the real world. RESULTS Deviations from normal symmetry, due to the presence of lesions, are detectable using this new modality. The ease of detection improves with larger lesions and those far from the plane of symmetry. Quantitative metrics, as well as an image, help to robustly detect and identify both the presence of an abnormality and the cause (haemorrhagic or ischaemic lesion in the scenarios tested) or indeed indicate where no detection is possible. CONCLUSION Symmetry difference EIT is a valuable new modality that is applicable to cases where the 'normal' features symmetry across a plane. Significantly, a change in the region of interest is not required and hence this technique may be suited to static or quasi-static cases where time difference EIT cannot be used.
Collapse
Affiliation(s)
- Barry McDermott
- Translational Medical Device Lab, National University of Ireland Galway, Galway, Ireland
| | | | | | | | | |
Collapse
|
102
|
Luo Y, Abiri P, Zhang S, Chang CC, Kaboodrangi AH, Li R, Sahib AK, Bui A, Kumar R, Woo M, Li Z, Packard RRS, Tai YC, Hsiai TK. Non-Invasive Electrical Impedance Tomography for Multi-Scale Detection of Liver Fat Content. Theranostics 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] [MESH Headings] [Grants] [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.
Collapse
Affiliation(s)
- Yuan Luo
- Department of Medical Engineering, California Institute of Technology, Pasadena, California
| | - Parinaz Abiri
- 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
| | - Shell Zhang
- Department of Medical Engineering, California Institute of Technology, Pasadena, California
| | - Chih-Chiang Chang
- Department of Bioengineering, Henry Samueli School of Engineering and Applied Sciences, University of California, Los Angeles, California
| | - Amir H. Kaboodrangi
- Department of Bioengineering, Henry Samueli School of Engineering and Applied Sciences, University of California, Los Angeles, California
| | - Rongsong Li
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Ashish K. Sahib
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, California
- Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Alex Bui
- Department of Bioengineering, Henry Samueli School of Engineering and Applied Sciences, University of California, Los Angeles, California
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Rajesh Kumar
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, California
- Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Mary Woo
- School of Nursing, University of California, Los Angeles, California
| | - Zhaoping Li
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - René R. Sevag Packard
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Yu-Chong Tai
- Department of Medical Engineering, California Institute of Technology, Pasadena, California
| | - 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
| |
Collapse
|
103
|
Takhti M, Teng YC, Odame K. A 10 MHz Read-Out Chain for Electrical Impedance Tomography. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2018; 12:222-230. [PMID: 29377810 DOI: 10.1109/tbcas.2017.2778288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This paper presents the design and implementation of a read-out chain for electrical impedance tomography (EIT) imaging. The EIT imaging approach can be incorporated to take spectral images of the tissue under study, offering an affordable, portable device for home health monitoring. A fast read-out channel covering a wide range of frequencies is a must for such applications. The proposed read-out channel comprising a programmable gain instrumentation amplifier, an analog-to-digital converter (ADC), and an ADC driver is designed and fabricated in a 0.18 m CMOS technology. The proposed read-out chain operates over the wide frequency range of 100 Hz to 10 MHz, with an average signal-to-noise ratio of more than 60 dB. The entire read-out channel consumes between 6.9 and 21.8 mW, depending on its frequency of operation.
Collapse
|
104
|
da Silva Ramos FJ, Hovnanian A, Souza R, Azevedo LCP, Amato MBP, Costa ELV. Estimation of Stroke Volume and Stroke Volume Changes by Electrical Impedance Tomography. Anesth Analg 2018; 126:102-110. [PMID: 28742775 DOI: 10.1213/ane.0000000000002271] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Electrical impedance tomography (EIT) is a noninvasive imaging method that identifies changes in air and blood volume based on thoracic impedance changes. Recently, there has been growing interest in EIT to measure stroke volume (SV). The objectives of this study are as follows: (1) to evaluate the ability of systolic impedance variations (ΔZsys) to track changes in SV in relation to a baseline condition; (2) to assess the relationship of ΔZsys and SV in experimental subjects; and (3) to identify the influence of body dimensions on the relationship between ΔZsys and SV. METHODS Twelve Agroceres pigs were instrumented with transpulmonary thermodilution catheter and EIT and were mechanically ventilated in a random order using different settings of tidal volume (VT) and positive end-expiratory pressure (PEEP): VT 10 mL·kg and PEEP 10 cm H2O, VT 10 mL·kg and PEEP 5 cm H2O, VT 6 mL·kg and PEEP 10 cm H2O, and VT 6 mL·kg and PEEP 5 cm H2O. After baseline data collection, subjects were submitted to hemorrhagic shock and successive fluid challenges. RESULTS A total of 204 paired measurements of SV and ΔZsys were obtained. The 4-quadrant plot showed acceptable trending ability with a concordance rate of 91.2%. Changes in ΔZsys after fluid challenges presented an area under the curve of 0.83 (95% confidence interval, 0.74-0.92) to evaluate SV changes. Conversely, the linear association between ΔZsys and SV was poor, with R from linear mixed model of 0.35. Adding information on body dimensions improved the linear association between ΔZsys and SV up to R from linear mixed model of 0.85. CONCLUSIONS EIT showed good trending ability and is a promising hemodynamic monitoring tool. Measurements of absolute SV require that body dimensions be taken into account.
Collapse
Affiliation(s)
- Fernando José da Silva Ramos
- From the Department of Intensive Care and Anesthesiology Research Laboratory, Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil
| | - André Hovnanian
- From the Department of Intensive Care and Anesthesiology Research Laboratory, Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil.,Respiratory Intensive Care Unit, University of São Paulo School of Medicine, São Paulo, Brazil
| | - Rogério Souza
- Respiratory Intensive Care Unit, University of São Paulo School of Medicine, São Paulo, Brazil
| | - Luciano C P Azevedo
- From the Department of Intensive Care and Anesthesiology Research Laboratory, Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil
| | - Marcelo B P Amato
- Respiratory Intensive Care Unit, University of São Paulo School of Medicine, São Paulo, Brazil
| | - Eduardo L V Costa
- From the Department of Intensive Care and Anesthesiology Research Laboratory, Research and Education Institute, Hospital Sírio-Libanês, São Paulo, Brazil.,Respiratory Intensive Care Unit, University of São Paulo School of Medicine, São Paulo, Brazil
| |
Collapse
|
105
|
McDermott B, McGinley B, Krukiewicz K, Divilly B, Jones M, Biggs M, O’Halloran M, Porter E. Stable tissue-mimicking materials and an anatomically realistic, adjustable head phantom for electrical impedance tomography. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa922d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
106
|
|
107
|
Liu J, Wang Y, Katscher U, He B. Electrical Properties Tomography Based on $B_{{1}}$ Maps in MRI: Principles, Applications, and Challenges. IEEE Trans Biomed Eng 2017; 64:2515-2530. [PMID: 28829299 PMCID: PMC5675043 DOI: 10.1109/tbme.2017.2725140] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE The purpose is to provide a comprehensive review of the electrical properties tomography (EPT) technique, which was introduced to image the electrical properties (EPs) of tissue noninvasively by exploiting the measured field data of MRI. METHODS We reviewed the principle of EPT, reconstruction methods, biomedical applications such as tumor imaging, and existing challenges. As a key application of EPT, the estimation of specific absorption rate (SAR) due to MRI was discussed in the background of elevated risk of tissue heating at high field. RESULTS AND CONCLUSION Since the originally proposed local, homogeneous Helmholtz equation-based reconstruction algorithm, advanced EPT algorithms have emerged to address the challenges of EPT, including reconstruction error near tissue boundaries, noise sensitivity, inaccurate phase estimation, and elimination of the unmeasurable component, along with demonstrations of in vivo experiments. EPT techniques have been applied to investigate EPs of both healthy and pathological tissues in vivo and factors contributing to various EP value, including sodium, water content, etc. More studies are anticipated to consolidate the current findings. EPT-based subject-specific SAR estimation has led to in vivo demonstration of its feasibility and prediction of temperature increase of phantom during MRI scans merely using measured data. SIGNIFICANCE EPT has the advantage of high resolution and practical feasibility in a clinical setup for imaging the biomedically interesting EPs of tissue in the radiofrequency range. EPT-based SAR estimation is another promising topic for predicting tissue heating of individual subjects during a specific MRI scan.
Collapse
Affiliation(s)
- Jiaen Liu
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Yicun Wang
- Department of Biomedical Engineering, University of Minnesota, Minnesota, 55455, USA
| | | | - Bin He
- Department of Biomedical Engineering and Institute for Engineering in Medicine, University of Minnesota, Minnesota, 55455, USA
| |
Collapse
|
108
|
Mazzoni MB, Perri A, Plebani AM, Ferrari S, Amelio G, Rocchi A, Consonni D, Milani GP, Fossali EF. Electrical impedance tomography in children with community acquired pneumonia: preliminary data. Respir Med 2017; 130:9-12. [DOI: 10.1016/j.rmed.2017.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 05/23/2017] [Accepted: 07/03/2017] [Indexed: 11/30/2022]
|
109
|
Muller PA, Mueller JL, Mellenthin MM. Real-Time Implementation of Calderón's Method on Subject-Specific Domains. IEEE TRANSACTIONS ON MEDICAL IMAGING 2017; 36:1868-1875. [PMID: 28436855 DOI: 10.1109/tmi.2017.2695893] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A real-time implementation of Calderón's method for the reconstruction of a 2-D conductivity from electrical impedance tomography data is presented, in which domain-specific modeling is taken into account. This is the first implementation of Calderón's method that accounts for correct modeling of non-symmetric domain boundaries in image reconstruction. The domain-specific Calderón's method is derived and reconstructions from experimental tank data are presented, quantifying the distortion when correct modeling is not included in the reconstruction algorithm. Reconstructions from human subject volunteers are presented, demonstrating the method's effectiveness for imaging changes due to ventilation and perfusion in the human thorax.
Collapse
|
110
|
Martin S, Choi CTM. A Post-Processing Method for Three-Dimensional Electrical Impedance Tomography. Sci Rep 2017; 7:7212. [PMID: 28775284 PMCID: PMC5543057 DOI: 10.1038/s41598-017-07727-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 06/29/2017] [Indexed: 11/13/2022] Open
Abstract
Electrical impedance tomography is a modern biomedical imaging method. Its goal is to image the electrical properties of human tissues. This approach is safe for the patient's health, is non-invasive and has no known hazards. However, the approach suffers from low accuracy. Linear inverse solvers are commonly used in medical applications, as they are strongly robust to noise. However, linear methods can give only an approximation of the solution that corresponds to a linear perturbation from an initial estimate. This paper proposes a novel reconstruction process. After applying a linear solver, the conductivity distribution is post-processed with a nonlinear algorithm, with the aim of reproducing the abrupt change in conductivity at the boundaries between tissues or organs. The results are used to compare the proposed method with three other widely used methods. The proposed method offers higher quality images and a higher robustness to noise, and significantly reduces the error associated with image reconstruction.
Collapse
Affiliation(s)
- Sébastien Martin
- Department of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu City, 30010, Taiwan
| | - Charles T M Choi
- Department of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu City, 30010, Taiwan.
- Institute of Biomedical Engineering, National Chiao Tung University, Hsinchu City, 30010, Taiwan.
| |
Collapse
|
111
|
Roth CJ, Becher T, Frerichs I, Weiler N, Wall WA. Coupling of EIT with computational lung modeling for predicting patient-specific ventilatory responses. J Appl Physiol (1985) 2017; 122:855-867. [DOI: 10.1152/japplphysiol.00236.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 12/06/2016] [Accepted: 12/06/2016] [Indexed: 12/19/2022] Open
Abstract
Providing optimal personalized mechanical ventilation for patients with acute or chronic respiratory failure is still a challenge within a clinical setting for each case anew. In this article, we integrate electrical impedance tomography (EIT) monitoring into a powerful patient-specific computational lung model to create an approach for personalizing protective ventilatory treatment. The underlying computational lung model is based on a single computed tomography scan and able to predict global airflow quantities, as well as local tissue aeration and strains for any ventilation maneuver. For validation, a novel “virtual EIT” module is added to our computational lung model, allowing to simulate EIT images based on the patient's thorax geometry and the results of our numerically predicted tissue aeration. Clinically measured EIT images are not used to calibrate the computational model. Thus they provide an independent method to validate the computational predictions at high temporal resolution. The performance of this coupling approach has been tested in an example patient with acute respiratory distress syndrome. The method shows good agreement between computationally predicted and clinically measured airflow data and EIT images. These results imply that the proposed framework can be used for numerical prediction of patient-specific responses to certain therapeutic measures before applying them to an actual patient. In the long run, definition of patient-specific optimal ventilation protocols might be assisted by computational modeling. NEW & NOTEWORTHY In this work, we present a patient-specific computational lung model that is able to predict global and local ventilatory quantities for a given patient and any selected ventilation protocol. For the first time, such a predictive lung model is equipped with a virtual electrical impedance tomography module allowing real-time validation of the computed results with the patient measurements. First promising results obtained in an acute respiratory distress syndrome patient show the potential of this approach for personalized computationally guided optimization of mechanical ventilation in future.
Collapse
Affiliation(s)
- Christian J. Roth
- Institute for Computational Mechanics, Technical University of Munich, Munich, Germany; and
| | - Tobias Becher
- Department of Anesthesiology and Intensive Care Medicine, Christian Albrechts University, Kiel, Germany
| | - Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, Christian Albrechts University, Kiel, Germany
| | - Norbert Weiler
- Department of Anesthesiology and Intensive Care Medicine, Christian Albrechts University, Kiel, Germany
| | - Wolfgang A. Wall
- Institute for Computational Mechanics, Technical University of Munich, Munich, Germany; and
| |
Collapse
|
112
|
Murphy EK, Mahara A, Halter RJ. Absolute Reconstructions Using Rotational Electrical Impedance Tomography for Breast Cancer Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2017; 36:892-903. [PMID: 28113311 PMCID: PMC5512723 DOI: 10.1109/tmi.2016.2640944] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A rotational Electrical Impedance Tomography (rEIT) methodology is described and shown to produce spatially accurate absolute reconstructions with improved image contrast and an improved ability to distinguish closely spaced inclusions compared to traditional EIT on data recorded from cylindrical and breast-shaped tanks. Rotations of the tank without altering the interior conductivity distribution are used to produce the rEIT data. Quantitatively, rEIT was able to distinguish two inclusions that were 1.5 cm closer together than traditional EIT could achieve for inclusions placed 2 to 3 cm from the center for the cylindrical tank, and rEIT was able to distinguish two tumor-like inclusions where traditional EIT could not reliably do so. Mathematical analysis showed that rEIT improves the number of stable singular vectors by up to 4.2 and 4.7 times than that of traditional EIT for the cylindrical and breast-shaped tanks, respectively, which is an indication of improved resolution. Direct investigations into measurements revealed minimum rotation angles that should yield data uncorrupted by noise. Two inverse approaches (one that inverts then fuses the data (I/DF) and one that fuses the data then inverts (DF/I)) and two mesh modeling approaches were considered. It was found that DF/I produces far better results compared to I/DF and a rotated-mesh approach produces further improvements. The ability to obtain improved absolute reconstructions using rEIT on a practical clinical scenario (breast-shaped tank experiment) is an important step towards using rEIT to improve previous EIT results in medical applications.
Collapse
|
113
|
Ammari H, Boulier T, Garnier J, Wang H. Mathematical modelling of the electric sense of fish: the role of multi-frequency measurements and movement. BIOINSPIRATION & BIOMIMETICS 2017; 12:025002. [PMID: 28141576 DOI: 10.1088/1748-3190/aa5296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Understanding active electrolocation in weakly electric fish remains a challenging issue. In this article we propose a mathematical formulation of this problem, in terms of partial differential equations. This allows us to detail two algorithms: one for localizing a target using the multi-frequency aspect of the signal, and another one for identifying the shape of this target. Shape recognition is designed in a machine learning point of view, and takes advantage of both the multi-frequency setup and the movement of the fish around its prey. Numerical simulations are shown for the computation of the electric field emitted and sensed by the fish; they are then used as an input for the two algorithms.
Collapse
Affiliation(s)
- Habib Ammari
- Department of Mathematics, ETH Zürich, Rämistrasse 101, CH-8092 Zürich
| | | | | | | |
Collapse
|
114
|
Sanchez B, Rutkove SB. Electrical Impedance Myography and Its Applications in Neuromuscular Disorders. Neurotherapeutics 2017; 14:107-118. [PMID: 27812921 PMCID: PMC5233633 DOI: 10.1007/s13311-016-0491-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Electrical impedance myography (EIM) refers to the specific application of electrical bioimpedance techniques for the assessment of neuromuscular disorders. In EIM, a weak, high-frequency electrical current is applied to a muscle or muscle group of interest and the resulting voltages measured. Among its advantages, the technique can be used noninvasively across a variety of disorders and requires limited subject cooperation and evaluator training to obtain accurate and repeatable data. Studies in both animals and human subjects support its potential utility as a primary diagnostic tool, as well as a biomarker for clinical trial or individual patient use. This review begins by providing an overview of the current state and technological advances in electrical impedance myography and its specific application to the study of muscle. We then provide a summary of the clinical and preclinical applications of EIM for neuromuscular conditions, and conclude with an evaluation of ongoing research efforts and future developments.
Collapse
Affiliation(s)
- Benjamin Sanchez
- Department of Neurology, Division of Neuromuscular Disease, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - Seward B Rutkove
- Department of Neurology, Division of Neuromuscular Disease, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA.
| |
Collapse
|
115
|
Electrical Impedance Spectroscopy for Quality Assessment of Meat and Fish: A Review on Basic Principles, Measurement Methods, and Recent Advances. J FOOD QUALITY 2017. [DOI: 10.1155/2017/6370739] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Electrical impedance spectroscopy (EIS), as an effective analytical technique for electrochemical system, has shown a wide application for food quality and safety assessment recently. Individual differences of livestock cause high variation in quality of raw meat and fish and their commercialized products. Therefore, in order to obtain the definite quality information and ensure the quality of each product, a fast and on-line detection technology is demanded to be developed to monitor product processing. EIS has advantages of being fast, nondestructive, inexpensive, and easily implemented and shows potential to develop on-line detecting instrument to replace traditional methods to realize time, cost, skilled persons saving and further quality grading. This review outlines the fundamental theories and two common measurement methods of EIS applied to biological tissue, summarizes its application specifically for quality assessment of meat and fish, and discusses challenges and future trends of EIS technology applied for meat and fish quality assessment.
Collapse
|
116
|
On-site Rapid Diagnosis of Intracranial Hematoma using Portable Multi-slice Microwave Imaging System. Sci Rep 2016; 6:37620. [PMID: 27897197 PMCID: PMC5126641 DOI: 10.1038/srep37620] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 11/01/2016] [Indexed: 11/28/2022] Open
Abstract
Rapid, on-the-spot diagnostic and monitoring systems are vital for the survival of patients with intracranial hematoma, as their conditions drastically deteriorate with time. To address the limited accessibility, high costs and static structure of currently used MRI and CT scanners, a portable non-invasive multi-slice microwave imaging system is presented for accurate 3D localization of hematoma inside human head. This diagnostic system provides fast data acquisition and imaging compared to the existing systems by means of a compact array of low-profile, unidirectional antennas with wideband operation. The 3D printed low-cost and portable system can be installed in an ambulance for rapid on-site diagnosis by paramedics. In this paper, the multi-slice head imaging system’s operating principle is numerically analysed and experimentally validated on realistic head phantoms. Quantitative analyses demonstrate that the multi-slice head imaging system is able to generate better quality reconstructed images providing 70% higher average signal to clutter ratio, 25% enhanced maximum signal to clutter ratio and with around 60% hematoma target localization compared to the previous head imaging systems. Nevertheless, numerical and experimental results demonstrate that previous reported 2D imaging systems are vulnerable to localization error, which is overcome in the presented multi-slice 3D imaging system. The non-ionizing system, which uses safe levels of very low microwave power, is also tested on human subjects. Results of realistic phantom and subjects demonstrate the feasibility of the system in future preclinical trials.
Collapse
|
117
|
Wilsterman MEF, de Jager P, Blokpoel R, Frerichs I, Dijkstra SK, Albers MJIJ, Burgerhof JGM, Markhorst DG, Kneyber MCJ. Short-term effects of neuromuscular blockade on global and regional lung mechanics, oxygenation and ventilation in pediatric acute hypoxemic respiratory failure. Ann Intensive Care 2016; 6:103. [PMID: 27783382 PMCID: PMC5081313 DOI: 10.1186/s13613-016-0206-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 10/17/2016] [Indexed: 01/10/2023] Open
Abstract
Background Neuromuscular blockade (NMB) has been shown to improve outcome in acute respiratory distress syndrome (ARDS) in adults, challenging maintaining spontaneous breathing when there is severe lung injury. We tested in a prospective physiological study the hypothesis that continuous administration of NMB agents in mechanically ventilated children with severe acute hypoxemic respiratory failure (AHRF) improves the oxygenation index without a redistribution of tidal volume VT toward non-dependent lung zones. Methods Oxygenation index, PaO2/FiO2 ratio, lung mechanics (plateau pressure, mean airway pressure, respiratory system compliance and resistance), hemodynamics (heart rate, central venous and arterial blood pressures), oxygenation [oxygenation index (OI), PaO2/FiO2 and SpO2/FiO2], ventilation (physiological dead space-to-VT ratio) and electrical impedance tomography measured changes in end-expiratory lung volume (EELV), and VT distribution was measured before and 15 min after the start of continuous infusion of rocuronium 1 mg/kg. Patients were ventilated in a time-cycled, pressure-limited mode with pre-set VT. All ventilator settings were not changed during the study. Results Twenty-two patients were studied (N = 18 met the criteria for pediatric ARDS). Median age (25–75 interquartile range) was 15 (7.8–77.5) weeks. Pulmonary pathology was present in 77.3%. The median lung injury score was 9 (8–10). The overall median CoV and regional lung filling characteristics were not affected by NMB, indicating no ventilation shift toward the non-dependent lung zones. Regional analysis showed a homogeneous time course of lung inflation during inspiration, indicating no tendency to atelectasis after the introduction of NMB. NMB decreased the mean airway pressure (p = 0.039) and OI (p = 0.039) in all patients. There were no significant changes in lung mechanics, hemodynamics and EELV. Subgroup analysis showed that OI decreased (p = 0.01) and PaO2/FiO2 increased (p = 0.02) in patients with moderate or severe PARDS. Conclusions NMB resulted in an improved oxygenation index in pediatric patients with AHRF. Distribution of VT and regional lung filling characteristics were not affected.
Collapse
Affiliation(s)
- Marlon E F Wilsterman
- Division of Paediatric Intensive Care, Department of Paediatrics, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands.,Department of Paediatrics, Nij Smellinghe Hospital, Drachten, The Netherlands
| | - Pauline de Jager
- Division of Paediatric Intensive Care, Department of Paediatrics, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands
| | - Robert Blokpoel
- Division of Paediatric Intensive Care, Department of Paediatrics, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands
| | - Inez Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Sandra K Dijkstra
- Division of Paediatric Intensive Care, Department of Paediatrics, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands
| | - Marcel J I J Albers
- Division of Paediatric Intensive Care, Department of Paediatrics, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands
| | - Johannes G M Burgerhof
- Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Dick G Markhorst
- Division of Paediatric Intensive Care, Department of Paediatrics, VU University Medical Center, Amsterdam, The Netherlands
| | - Martin C J Kneyber
- Division of Paediatric Intensive Care, Department of Paediatrics, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands. .,Critical Care, Anaesthesia, Peri-operative Medicine and Emergency Medicine (CAPE), University of Groningen, Groningen, The Netherlands.
| |
Collapse
|
118
|
Liu D, Kolehmainen V, Siltanen S, Laukkanen AM, Seppanen A. Nonlinear Difference Imaging Approach to Three-Dimensional Electrical Impedance Tomography in the Presence of Geometric Modeling Errors. IEEE Trans Biomed Eng 2016; 63:1956-1965. [DOI: 10.1109/tbme.2015.2509508] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
119
|
Mellenthin MM, Mueller JL, Bueno de Camargo EDL, Silva de Moura F, Hamilton SJ, Gonzalez Lima R. The ACE1 thoracic Electrical Impedance Tomography system for ventilation and perfusion. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:4073-6. [PMID: 26737189 DOI: 10.1109/embc.2015.7319289] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Electrical Impedance Tomography (EIT) is a technique which can image the varying electrical properties of biological tissues. For clinical use of EIT, it can be advantageous to know both tissue conductivity and permittivity. Presented is the hardware design for the pairwise current injection active complex electrode (ACE1) EIT system which measures phasic voltages for conductivity and permittivity image reconstruction. In this system, alternating current is injected on electrodes on the boundary of a domain and single-ended voltage measurements are used in image reconstructions of the domain's interior and in calculating the current applied at the electrodes.
Collapse
|
120
|
Schullcke B, Krueger-Ziolek S, Gong B, Mueller-Lisse U, Moeller K. Compensation for large thorax excursions in EIT imaging. Physiol Meas 2016; 37:1605-23. [PMID: 27531053 DOI: 10.1088/0967-3334/37/9/1605] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Besides the application of EIT in the intensive care unit it has recently also been used in spontaneously breathing patients suffering from asthma bronchiole, cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD). In these cases large thorax excursions during deep inspiration, e.g. during lung function testing, lead to artifacts in the reconstructed images. In this paper we introduce a new approach to compensate for image artifacts resulting from excursion induced changes in boundary voltages. It is shown in a simulation study that boundary voltage change due to thorax excursion on a homogeneous model can be used to modify the measured voltages and thus reduce the impact of thorax excursion on the reconstructed images. The applicability of the method on human subjects is demonstrated utilizing a motion-tracking-system. The proposed technique leads to fewer artifacts in the reconstructed images and improves image quality without substantial increase in computational effort, making the approach suitable for real-time imaging of lung ventilation. This might help to establish EIT as a supplemental tool for lung function tests in spontaneously breathing patients to support clinicians in diagnosis and monitoring of disease progression.
Collapse
Affiliation(s)
- B Schullcke
- Institute of Technical Medicine, Furtwangen University, VS-Schwenningen, Germany. Department of Radiology, University of Munich, Munich, Germany
| | | | | | | | | |
Collapse
|
121
|
Schullcke B, Krueger-Ziolek S, Gong B, Mueller-Lisse U, Moeller K. Simultaneous application of two independent EIT devices for real-time multi-plane imaging. Physiol Meas 2016; 37:1541-55. [DOI: 10.1088/0967-3334/37/9/1541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
122
|
Arango M, Martínez G, Torres G. Advances in the Interpretation of Tomographic Images as an Early Detection Method of Oil Palm Affected by Basal Stem Rot in Colombia. PLANT DISEASE 2016; 100:1559-1563. [PMID: 30686235 DOI: 10.1094/pdis-12-15-1473-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Basal stem rot, one of the most important diseases of oil palm in Southeast Asia, has also been identified in Colombia. The increase in disease incidence in the last decade has attracted the attention of producers and researchers. In the search for a procedure that allows for the early identification of diseased palm, Cenipalma evaluated the use of electrical impedance tomography to identify the different stages of development of basal stem rot. The tomograms were compared with transversal sections of healthy and diseased oil palm trees. Following Cenipalma's preliminary studies on early diagnosis of basal stem rot with tomography, the present study improved upon the technique by analyzing the tomograms of 209 diseased palm trees (confirmed by symptomatology), 346 asymptomatic palm trees, and 132 healthy palm trees. The minimum and maximum electric impedance values as well as the ratio between these values was recorded. The range of 1 to 95 Ω was used to represent the internal damage. The ratios averaged 5.1 for diseased, 1.9 for asymptomatic, and 1.5 for healthy palm trees. With the range and the ratio criteria established, it was possible to identify the disease in 100% of asymptomatic sampled palm trees. This study demonstrated that electrical impedance tomography is a powerful tool for early detection of basal stem rot, which can be used to establish an early disease management program.
Collapse
Affiliation(s)
- M Arango
- Pests and Diseases Program, Colombian Oil Palm Research Centre, Cenipalma. Bogota, Colombia
| | - G Martínez
- Pests and Diseases Program, Colombian Oil Palm Research Centre, Cenipalma. Bogota, Colombia
| | - G Torres
- Pests and Diseases Program, Colombian Oil Palm Research Centre, Cenipalma. Bogota, Colombia
| |
Collapse
|
123
|
Murphy EK, Mahara A, Halter RJ. A Novel Regularization Technique for Microendoscopic Electrical Impedance Tomography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2016; 35:1593-1603. [PMID: 26812707 DOI: 10.1109/tmi.2016.2520907] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A novel regularization technique is developed for end-fired microendoscopic electrical impedance tomography using the dual-mesh method. The new regularization technique coupled with appropriate forward modeling and inverse mesh design is shown to produce dramatically improved reconstructions over previous methods. 3D absolute and difference reconstructions from measured saline tank and ex vivo adipose and muscle tissue experiments are used to validate the approach. The ex vivo experiments are used as a surrogate for prostate tissue, which is the primary clinical application for the probe. Inclusion center of mass errors were less than 0.47 mm for tank experiments with inclusion depths and radial offsets ranging less than 3 mm and 1.5 mm, respectively. Absolute 3D reconstructions on the tissue show quantitatively good accuracy and the ability to spatially distinguish small tissue features (adipose strands of approximately 2.5 mm in width). The reconstruction algorithm developed provides strong evidence for the promise of surgical margin detection using microendoscopic EIT.
Collapse
|
124
|
Vogt B, Zhao Z, Zabel P, Weiler N, Frerichs I. Regional lung response to bronchodilator reversibility testing determined by electrical impedance tomography in chronic obstructive pulmonary disease. Am J Physiol Lung Cell Mol Physiol 2016; 311:L8-L19. [DOI: 10.1152/ajplung.00463.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 05/17/2016] [Indexed: 01/01/2023] Open
Abstract
Patients with obstructive lung diseases commonly undergo bronchodilator reversibility testing during examination of their pulmonary function by spirometry. A positive response is defined by an increase in forced expiratory volume in 1 s (FEV1). FEV1 is a rather nonspecific criterion not allowing the regional effects of bronchodilator to be assessed. We employed the imaging technique of electrical impedance tomography (EIT) to visualize the spatial and temporal ventilation distribution in 35 patients with chronic obstructive pulmonary disease at baseline and 5, 10, and 20 min after bronchodilator inhalation. EIT scanning was performed during tidal breathing and forced full expiration maneuver in parallel with spirometry. Ventilation distribution was determined by EIT by calculating the image pixel values of FEV1, forced vital capacity (FVC), tidal volume, peak flow, and mean forced expiratory flow between 25 and 75% of FVC. The global inhomogeneity indexes of each measure and histograms of pixel FEV1/FVC values were then determined to assess the bronchodilator effect on spatial ventilation distribution. Temporal ventilation distribution was analyzed from pixel values of times needed to exhale 75 and 90% of pixel FVC. Based on spirometric FEV1, significant bronchodilator response was found in 17 patients. These patients exhibited higher postbronchodilator values of all regional EIT-derived lung function measures in contrast to nonresponders. Ventilation distribution was inhomogeneous in both groups. Significant improvements were noted for spatial distribution of pixel FEV1 and tidal volume and temporal distribution in responders. By providing regional data, EIT might increase the diagnostic and prognostic information derived from reversibility testing.
Collapse
Affiliation(s)
- Barbara Vogt
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Zhanqi Zhao
- Department of Biomedical Engineering, Furtwangen University, Villingen-Schwenningen, Germany; and
| | - Peter Zabel
- Department of Pneumology, Medical Clinic, Research Center Borstel, Germany
| | - Norbert Weiler
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Inéz Frerichs
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| |
Collapse
|
125
|
Hou R, Martin PJ, Uppal HJ, Kowalski AJ. An investigation on using electrical resistance tomography (ERT) to monitor the removal of a non-Newtonian soil by water from a cleaning-in-place (CIP) circuit containing different pipe geometries. Chem Eng Res Des 2016. [DOI: 10.1016/j.cherd.2016.05.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
126
|
Martin S, Choi CTM. On the influence of spread constant in radial basis networks for electrical impedance tomography. Physiol Meas 2016; 37:801-19. [PMID: 27203367 DOI: 10.1088/0967-3334/37/6/801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Electrical impedance tomography (EIT) is a non-invasive imaging technique. The main task of this work is to solve a non-linear inverse problem, for which several techniques have been suggested, but none of which gives a very high degree of accuracy. This paper introduces a novel approach, based on radial basis function (RBF) artificial neural networks (ANNs), to solve this problem, and uses several ANNs to obtain the best solution to the EIT inverse problem. ANNs have the potential to directly estimate the solution of the inverse problem with a high degree of accuracy. While different radial basis neural networks do not always perform well on different problems, they usually give good results on some specific problems. This paper evidences a strong correlation between the area of the target and the spread constant of the RBF network that gives the best reconstruction. A solution to automatically estimate the size of the target and pick the best neural network directly from voltage measurements is presented, making the reconstruction process automatic. By automatically selecting the best ANN for each specific set of voltage measurements, the proposed solution gives a more accurate reconstruction of both small and large targets.
Collapse
Affiliation(s)
- Sébastien Martin
- National Chiao Tung University, 1001 University Rd, Hsinchu 30010, Taiwan, Republic of China
| | | |
Collapse
|
127
|
Jehl M, Aristovich K, Faulkner M, Holder D. Are patient specific meshes required for EIT head imaging? Physiol Meas 2016; 37:879-92. [DOI: 10.1088/0967-3334/37/6/879] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
128
|
Kimel-Naor S, Abboud S, Arad M. Parametric electrical impedance tomography for measuring bone mineral density in the pelvis using a computational model. Med Eng Phys 2016; 38:701-7. [PMID: 27185035 DOI: 10.1016/j.medengphy.2016.04.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 03/22/2016] [Accepted: 04/11/2016] [Indexed: 01/13/2023]
Abstract
Osteoporosis is defined as bone microstructure deterioration resulting a decrease of bone's strength. Measured bone mineral density (BMD) constitutes the main tool for Osteoporosis diagnosis, management, and defines patient's fracture risk. In the present study, parametric electrical impedance tomography (pEIT) method was examined for monitoring BMD, using a computerized simulation model and preliminary real measurements. A numerical solver was developed to simulate surface potentials measured over a 3D computerized pelvis model. Varying cortical and cancellous BMD were simulated by changing bone conductivity and permittivity. Up to 35% and 16% change was found in the real and imaginary modules of the calculated potential, respectively, while BMD changes from 100% (normal) to 60% (Osteoporosis). Negligible BMD relative error was obtained with SNR>60 [dB]. Position changes errors indicate that for long term monitoring, measurement should be taken at the same geometrical configuration with great accuracy. The numerical simulations were compared to actual measurements that were acquired from a healthy male subject using a five electrodes belt bioimpedance device. The results suggest that pEIT may provide an inexpensive easy to use tool for frequent monitoring BMD in small clinics during pharmacological treatment, as a complementary method to DEXA test.
Collapse
Affiliation(s)
- Shani Kimel-Naor
- Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Shimon Abboud
- Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel.
| | - Marina Arad
- Department of Geriatric Rehabilitation, Sheba Medical Center, Israel
| |
Collapse
|
129
|
Structural-functional lung imaging using a combined CT-EIT and a Discrete Cosine Transformation reconstruction method. Sci Rep 2016; 6:25951. [PMID: 27181695 PMCID: PMC4867600 DOI: 10.1038/srep25951] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 04/20/2016] [Indexed: 12/14/2022] Open
Abstract
Lung EIT is a functional imaging method that utilizes electrical currents to reconstruct images of conductivity changes inside the thorax. This technique is radiation free and applicable at the bedside, but lacks of spatial resolution compared to morphological imaging methods such as X-ray computed tomography (CT). In this article we describe an approach for EIT image reconstruction using morphologic information obtained from other structural imaging modalities. This leads to recon- structed images of lung ventilation that can easily be superimposed with structural CT or MRI images, which facilitates image interpretation. The approach is based on a Discrete Cosine Transformation (DCT) of an image of the considered transversal thorax slice. The use of DCT enables reduction of the dimensionality of the reconstruction and ensures that only conductivity changes of the lungs are reconstructed and displayed. The DCT based approach is well suited to fuse morphological image information with functional lung imaging at low computational costs. Results on simulated data indicate that this approach preserves the morphological structures of the lungs and avoids blurring of the solution. Images from patient measurements reveal the capabilities of the method and demonstrate benefits in possible applications.
Collapse
|
130
|
Ron A, Abboud S, Arad M. Home monitoring of bone density in the wrist—a parametric EIT computer modeling study. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/2/3/035002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
131
|
Pesenti A, Musch G, Lichtenstein D, Mojoli F, Amato MBP, Cinnella G, Gattinoni L, Quintel M. Imaging in acute respiratory distress syndrome. Intensive Care Med 2016; 42:686-698. [DOI: 10.1007/s00134-016-4328-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 03/11/2016] [Indexed: 11/30/2022]
|
132
|
Bera TK, Nagaraju J, Lubineau G. Electrical impedance spectroscopy (EIS)-based evaluation of biological tissue phantoms to study multifrequency electrical impedance tomography (Mf-EIT) systems. J Vis (Tokyo) 2016. [DOI: 10.1007/s12650-016-0351-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
133
|
Oziel M, Hjouj M, Gonzalez CA, Lavee J, Rubinsky B. Non-ionizing radiofrequency electromagnetic waves traversing the head can be used to detect cerebrovascular autoregulation responses. Sci Rep 2016; 6:21667. [PMID: 26898944 PMCID: PMC4761952 DOI: 10.1038/srep21667] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 01/26/2016] [Indexed: 11/25/2022] Open
Abstract
Monitoring changes in non-ionizing radiofrequency electromagnetic waves as they traverse the brain can detect the effects of stimuli employed in cerebrovascular autoregulation (CVA) tests on the brain, without contact and in real time. CVA is a physiological phenomenon of importance to health, used for diagnosis of a number of diseases of the brain with a vascular component. The technology described here is being developed for use in diagnosis of injuries and diseases of the brain in rural and economically underdeveloped parts of the world. A group of nine subjects participated in this pilot clinical evaluation of the technology. Substantial research remains to be done on correlating the measurements with physiology and anatomy.
Collapse
Affiliation(s)
- M. Oziel
- Faculty of Life Science, Bar Ilan University, Israel
| | - M. Hjouj
- Medical Imaging Department, Al-Quds University, Abu Dis, Palestine
| | - C. A. Gonzalez
- Instituto Politécnico Nacional-Escuela Superior de Medicina, DF, Mexico
- Universidad del Ejército y Fuerza Aérea-EMGS, DF, Mexico
| | - J. Lavee
- Faculty of Life Science, Bar Ilan University, Israel
- Heart Transplantation Unit, Department of Cardiac Surgery, Leviev Heart Center, Sheba Medical Center, Ramat Gan, Israel
| | - B. Rubinsky
- Department of Mechanical Engineering, University of California, Berkeley, CA 94720 USA
| |
Collapse
|
134
|
Nissinen A, Kaipio JP, Vauhkonen M, Kolehmainen V. Contrast enhancement in EIT imaging of the brain. Physiol Meas 2015; 37:1-24. [PMID: 26642274 DOI: 10.1088/0967-3334/37/1/1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We consider electrical impedance tomography (EIT) imaging of the brain. The brain is surrounded by the poorly conducting skull which has low conductivity compared to the brain. The skull layer causes a partial shielding effect which leads to weak sensitivity for the imaging of the brain tissue. In this paper we propose an approach based on the Bayesian approximation error approach, to enhance the contrast in brain imaging. With this approach, both the (uninteresting) geometry and the conductivity of the skull are embedded in the approximation error statistics, which leads to a computationally efficient algorithm that is able to detect features such as internal haemorrhage with significantly increased sensitivity and specificity. We evaluate the approach with simulations and phantom data.
Collapse
Affiliation(s)
- A Nissinen
- Department of Applied Physics, University of Eastern Finland, PO Box 1627, FIN-70211 Kuopio, Finland
| | | | | | | |
Collapse
|
135
|
Jehl M, Dedner A, Betcke T, Aristovich K, Klöfkorn R, Holder D. A fast parallel solver for the forward problem in electrical impedance tomography. IEEE Trans Biomed Eng 2015; 62:126-37. [PMID: 25069109 DOI: 10.1109/tbme.2014.2342280] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Electrical impedance tomography (EIT) is a noninvasive imaging modality, where imperceptible currents are applied to the skin and the resulting surface voltages are measured. It has the potential to distinguish between ischaemic and haemorrhagic stroke with a portable and inexpensive device. The image reconstruction relies on an accurate forward model of the experimental setup. Because of the relatively small signal in stroke EIT, the finite-element modeling requires meshes of more than 10 million elements. To study the requirements in the forward modeling in EIT and also to reduce the time for experimental image acquisition, it is necessary to reduce the run time of the forward computation. We show the implementation of a parallel forward solver for EIT using the Dune-Fem C++ library and demonstrate its performance on many CPU's of a computer cluster. For a typical EIT application a direct solver was significantly slower and not an alternative to iterative solvers with multigrid preconditioning. With this new solver, we can compute the forward solutions and the Jacobian matrix of a typical EIT application with 30 electrodes on a 15-million element mesh in less than 15 min. This makes it a valuable tool for simulation studies and EIT applications with high precision requirements. It is freely available for download.
Collapse
|
136
|
Schullcke B, Gong B, Krueger-Ziolek S, Moeller K. Improving image quality in EIT imaging by measurement of thorax excursion. CURRENT DIRECTIONS IN BIOMEDICAL ENGINEERING 2015. [DOI: 10.1515/cdbme-2015-0068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Electrical Impedance Tomography (EIT) is used to visualize the regional ventilation of the lungs using voltage measurements on the surface of the thorax. Unfortunately the image reconstruction process is sensitive to shape deformation. During breathing the inevitable expansion of the thorax influences measured boundary voltages which leads to artifacts in the reconstructed images. A camera based motion-tracking-system was used to measure thorax excursion during breathing and systematically modify measured voltages. Results indicate that image artefacts can be reduced if the measured voltages are modified based on the measured thorax excursion.
Collapse
Affiliation(s)
- Benjamin Schullcke
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Bo Gong
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Sabine Krueger-Ziolek
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| | - Knut Moeller
- Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany
| |
Collapse
|
137
|
Helen L, O'Donnell BD, Moore E. Nerve localization techniques for peripheral nerve block and possible future directions. Acta Anaesthesiol Scand 2015; 59:962-74. [PMID: 25997933 DOI: 10.1111/aas.12544] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 03/24/2015] [Accepted: 04/05/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Ultrasound guidance is now a standard nerve localization technique for peripheral nerve block (PNB). Ultrasonography allows simultaneous visualization of the target nerve, needle, local anesthetic injectate, and surrounding anatomical structures. Accurate deposition of local anesthetic next to the nerve is essential to the success of the nerve block procedure. Due to limitations in the visibility of both needle tip and nerve surface, the precise relationship between needle tip and target nerve is unknown at the moment of injection. Importantly, nerve injury may result both from an inappropriately placed needle tip and inappropriately placed local anesthetic. The relationship between the block needle tip and target nerve is of paramount importance to the safe conduct of peripheral nerve block. METHODS This review summarizes the evolution of nerve localization in regional anesthesia, characterizes a problem faced by clinicians in performing ultrasound-guided nerve block, and explores the potential technological solutions to this problem. RESULTS To date, technology newly applied to PNB includes real-time 3D imaging, multi-planar magnetic needle guidance, and in-line injection pressure monitoring. This review postulates that optical reflectance spectroscopy and bioimpedance may allow for accurate identification of the relationship between needle tip and target nerve, currently a high priority deficit in PNB techniques. CONCLUSIONS Until it is known how best to define the relationship between needle and nerve at the moment of injection, some common sense principles are suggested.
Collapse
Affiliation(s)
- L. Helen
- Sensing and Separation Group; Chemistry Department and Life Science Interface Group; Tyndall National Institute; University College Cork; Cork Ireland
| | - B. D. O'Donnell
- Department of Anesthesia; Cork University Hospital & ASSERT for Health Centre; University College Cork; Cork Ireland
| | - E. Moore
- Sensing and Separation Group; Chemistry Department and Life Science Interface Group; Tyndall National Institute; University College Cork; Cork Ireland
| |
Collapse
|
138
|
Godavarty A, Rodriguez S, Jung YJ, Gonzalez S. Optical imaging for breast cancer prescreening. BREAST CANCER-TARGETS AND THERAPY 2015; 7:193-209. [PMID: 26229503 PMCID: PMC4516032 DOI: 10.2147/bctt.s51702] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Breast cancer prescreening is carried out prior to the gold standard screening using X-ray mammography and/or ultrasound. Prescreening is typically carried out using clinical breast examination (CBE) or self-breast examinations (SBEs). Since CBE and SBE have high false-positive rates, there is a need for a low-cost, noninvasive, non-radiative, and portable imaging modality that can be used as a prescreening tool to complement CBE/SBE. This review focuses on the various hand-held optical imaging devices that have been developed and applied toward early-stage breast cancer detection or as a prescreening tool via phantom, in vivo, and breast cancer imaging studies. Apart from the various optical devices developed by different research groups, a wide-field fiber-free near-infrared optical scanner has been developed for transillumination-based breast imaging in our Optical Imaging Laboratory. Preliminary in vivo studies on normal breast tissues, with absorption-contrasted targets placed in the intramammary fold, detected targets as deep as 8.8 cm. Future work involves in vivo imaging studies on breast cancer subjects and comparison with the gold standard X-ray mammography approach.
Collapse
Affiliation(s)
- Anuradha Godavarty
- Optical Imaging Laboratory, Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| | - Suset Rodriguez
- Optical Imaging Laboratory, Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| | - Young-Jin Jung
- Department of Radiological Science, Dongseo University, Busan, South Korea
| | - Stephanie Gonzalez
- Optical Imaging Laboratory, Department of Biomedical Engineering, Florida International University, Miami, FL, USA
| |
Collapse
|
139
|
Meir A, Rubinsky B. Electrical impedance tomography of electrolysis. PLoS One 2015; 10:e0126332. [PMID: 26039686 PMCID: PMC4454594 DOI: 10.1371/journal.pone.0126332] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 04/01/2015] [Indexed: 11/27/2022] Open
Abstract
The primary goal of this study is to explore the hypothesis that changes in pH during electrolysis can be detected with Electrical Impedance Tomography (EIT). The study has relevance to real time control of minimally invasive surgery with electrolytic ablation. To investigate the hypothesis, we compare EIT reconstructed images to optical images acquired using pH-sensitive dyes embedded in a physiological saline agar gel phantom treated with electrolysis. We further demonstrate the biological relevance of our work using a bacterial E.Coli model, grown on the phantom. The results demonstrate the ability of EIT to image pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E.coli model. The results are promising, and invite further experimental explorations.
Collapse
Affiliation(s)
- Arie Meir
- Biophysics Graduate Program, University of California, Berkeley, California, United States of America
| | - Boris Rubinsky
- Department of Mechanical Engineering, University of California, Berkeley, California, United States of America
| |
Collapse
|
140
|
Antink CH, Pikkemaat R, Malmivuo J, Leonhardt S. A shape-based quality evaluation and reconstruction method for electrical impedance tomography. Physiol Meas 2015; 36:1161-77. [PMID: 26008150 DOI: 10.1088/0967-3334/36/6/1161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Linear methods of reconstruction play an important role in medical electrical impedance tomography (EIT) and there is a wide variety of algorithms based on several assumptions. With the Graz consensus reconstruction algorithm for EIT (GREIT), a novel linear reconstruction algorithm as well as a standardized framework for evaluating and comparing methods of reconstruction were introduced that found widespread acceptance in the community. In this paper, we propose a two-sided extension of this concept by first introducing a novel method of evaluation. Instead of being based on point-shaped resistivity distributions, we use 2759 pairs of real lung shapes for evaluation that were automatically segmented from human CT data. Necessarily, the figures of merit defined in GREIT were adjusted. Second, a linear method of reconstruction that uses orthonormal eigenimages as training data and a tunable desired point spread function are proposed. Using our novel method of evaluation, this approach is compared to the classical point-shaped approach. Results show that most figures of merit improve with the use of eigenimages as training data. Moreover, the possibility of tuning the reconstruction by modifying the desired point spread function is shown. Finally, the reconstruction of real EIT data shows that higher contrasts and fewer artifacts can be achieved in ventilation- and perfusion-related images.
Collapse
Affiliation(s)
- Christoph Hoog Antink
- Philips Chair for Medical Information Technology (MedIT), Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany
| | | | | | | |
Collapse
|
141
|
Roth CJ, Ehrl A, Becher T, Frerichs I, Schittny JC, Weiler N, Wall WA. Correlation between alveolar ventilation and electrical properties of lung parenchyma. Physiol Meas 2015; 36:1211-26. [DOI: 10.1088/0967-3334/36/6/1211] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
142
|
Tidal volume monitoring by electrical impedance tomography (EIT) using different regions of interest (ROI): Calibration equations. Biomed Signal Process Control 2015. [DOI: 10.1016/j.bspc.2014.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
143
|
Kao TJ, Amm B, Wang X, Boverman G, Shoudy D, Sabatini J, Ashe J, Newell J, Saulnier G, Isaacson D, Davenport D. Real-time 3D electrical impedance imaging for ventilation and perfusion of the lung in lateral decubitus position. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:1135-8. [PMID: 25570163 DOI: 10.1109/embc.2014.6943795] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We report a prototype Electrical Impedance Imaging System. It is able to detect the gravity-induced changes in the distributions of perfusion and ventilation in the lung between supine and lateral decubitus positions. Impedance data were collected on healthy volunteer subjects and 3D reconstructed images were produced in real-time, 20 frames per second on site, without using averaging or a contrast agent. Imaging data also can be reconstructed offline for further analysis.
Collapse
|
144
|
liu D, Kolehmainen V, Siltanen S, Laukkanen AM, Seppänen A. Estimation of conductivity changes in a region of interest with electrical impedance tomography. ACTA ACUST UNITED AC 2015. [DOI: 10.3934/ipi.2015.9.211] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
145
|
Schullcke B, Gong B, Moeller K. Steps towards 3D Electrical Impedance Tomography. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2015:5323-5326. [PMID: 26737493 DOI: 10.1109/embc.2015.7319593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electrical Impedance Tomography (EIT) is a promising imaging technique to visualize the dynamics of regional lung ventilation. 2D EIT has shown promise in monitoring ventilation therapy, with the drawback of only displaying a single horizontal slice of the lungs. Until now there are no generally accepted approaches available to generate meaningful 3D images in real-time. This paper describes general problems and first attempts to overcome those that may extend to a hierarchical scheme for 3D EIT imaging.
Collapse
|
146
|
|
147
|
Monitoring Lung Volumes During Mechanical Ventilation. PEDIATRIC AND NEONATAL MECHANICAL VENTILATION 2015. [PMCID: PMC7193716 DOI: 10.1007/978-3-642-01219-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Respiratory inductive plethysmography (RIP) is a non-invasive method of measuring change in lung volume which is well-established as a monitor of tidal ventilation and thus respiratory patterns in sleep medicine. As RIP is leak independent, can measure end-expiratory lung volume as well as tidal volume and is applicable to both the ventilated and spontaneously breathing patient, there has been a recent interest in its use as a bedside tool in the intensive care unit.
Collapse
|
148
|
Jung YM, Yun S. Impedance imaging with first-order TV regularization. IEEE TRANSACTIONS ON MEDICAL IMAGING 2015; 34:193-202. [PMID: 25163059 DOI: 10.1109/tmi.2014.2351014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
EIT problem is a typical inverse problem with serious ill-posedness. In general, regularization techniques are necessary for such ill-posed inverse problems. To overcome ill-posedness, the total variation (TV) regularization is widely used and it is also successfully applied to EIT. For realtime monitoring, a fast and robust image reconstruction algorithm is required. By exploiting recent advances in optimization, we propose a first-order TV algorithm for EIT, which simply consists of matrix-vector multiplications and in which the sparse structure of the system can be easily exploited. Furthermore, a typical smoothing parameter to overcome nondifferentibility of the TV term is not needed and a closed form solution can be applied in part using soft thresholding. It shows a fast reconstruction in the beginning. Numerical experiments using simulated data and real experimental data support our claim.
Collapse
|
149
|
Fu F, Li B, Dai M, Hu SJ, Li X, Xu CH, Wang B, Yang B, Tang MX, Dong XZ, Fei Z, Shi XT. Use of electrical impedance tomography to monitor regional cerebral edema during clinical dehydration treatment. PLoS One 2014; 9:e113202. [PMID: 25474474 PMCID: PMC4256286 DOI: 10.1371/journal.pone.0113202] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 10/24/2014] [Indexed: 01/10/2023] Open
Abstract
OBJECTIVE Variations of conductive fluid content in brain tissue (e.g. cerebral edema) change tissue impedance and can potentially be measured by Electrical Impedance Tomography (EIT), an emerging medical imaging technique. The objective of this work is to establish the feasibility of using EIT as an imaging tool for monitoring brain fluid content. DESIGN a prospective study. SETTING In this study EIT was used, for the first time, to monitor variations in cerebral fluid content in a clinical model with patients undergoing clinical dehydration treatment. The EIT system was developed in house and its imaging sensitivity and spatial resolution were evaluated on a saline-filled tank. PATIENTS 23 patients with brain edema. INTERVENTIONS The patients were continuously imaged by EIT for two hours after initiation of dehydration treatment using 0.5 g/kg intravenous infusion of mannitol for 20 minutes. MEASUREMENT AND MAIN RESULTS Overall impedance across the brain increased significantly before and after mannitol dehydration treatment (p = 0.0027). Of the all 23 patients, 14 showed high-level impedance increase and maintained this around 4 hours after the dehydration treatment whereas the other 9 also showed great impedance gain during the treatment but it gradually decreased after the treatment. Further analysis of the regions of interest in the EIT images revealed that diseased regions, identified on corresponding CT images, showed significantly less impedance changes than normal regions during the monitoring period, indicating variations in different patients' responses to such treatment. CONCLUSIONS EIT shows potential promise as an imaging tool for real-time and non-invasive monitoring of brain edema patients.
Collapse
Affiliation(s)
- Feng Fu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Bing Li
- Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Meng Dai
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Shi-Jie Hu
- Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Xia Li
- Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Can-Hua Xu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Bing Wang
- Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Bin Yang
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Meng-Xing Tang
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Xiu-Zhen Dong
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
- * E-mail: (XZD); (ZF); (XTS)
| | - Zhou Fei
- Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China
- * E-mail: (XZD); (ZF); (XTS)
| | - Xue-Tao Shi
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
- * E-mail: (XZD); (ZF); (XTS)
| |
Collapse
|
150
|
Borges JB, Hedenstierna G, Bergman JS, Amato MBP, Avenel J, Montmerle-Borgdorff S. First-time imaging of effects of inspired oxygen concentration on regional lung volumes and breathing pattern during hypergravity. Eur J Appl Physiol 2014; 115:353-63. [PMID: 25323531 DOI: 10.1007/s00421-014-3020-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 10/02/2014] [Indexed: 11/30/2022]
Abstract
PURPOSE Aeroatelectasis can develop in aircrew flying the latest generation high-performance aircraft. Causes alleged are relative hyperoxia, increased gravity in the head-to-foot direction (+Gz), and compression of legs and stomach by anti-G trousers (AGT). We aimed to assess, in real time, the effects of hyperoxia, +Gz accelerations and AGT inflation on changes in regional lung volumes and breathing pattern evaluated in an axial plane by electrical impedance tomography (EIT). METHODS The protocol mimicked a routine peacetime flight in combat aircraft. Eight subjects wearing AGT were studied in a human centrifuge during 1 h 15 min exposure of +1 to +3.5Gz. They performed this sequence three times, breathing AIR, 44.5 % O2 or 100 % O2. Continuous recording of functional EIT enabled uninterrupted assessment of regional lung volumes at the 5th intercostal level. Breathing pattern was also monitored. RESULTS EIT data showed that +3.5Gz, compared with any moment without hypergravity, caused an abrupt decrease in regional tidal volume (VT) and regional end-expiratory lung volume (EELV) measured in the EIT slice, independently of inspired oxygen concentration. Breathing AIR or 44.5 % O2, sub-regional EELV measured in the EIT slice decreased similarly in dorsal and ventral regions, but sub-regional VT measured in the EIT slice decreased significantly more dorsally than ventrally. Breathing 100 % O2, EELV and VT decreased similarly in both regions. Inspired tidal volume increased in hyperoxia, whereas breathing frequency increased in hypergravity and hyperoxia. CONCLUSIONS Our findings suggest that hypergravity and AGT inflation cause airway closure and air trapping in gravity-dependent lung regions, facilitating absorption atelectasis formation, in particular during hyperoxia.
Collapse
Affiliation(s)
- João Batista Borges
- Hedenstierna Laboratory, Department of Surgical Sciences, Section of Anaesthesiology & Critical Care, Uppsala University, Uppsala, Sweden,
| | | | | | | | | | | |
Collapse
|