Advanced Biomedical Engineering
Online ISSN : 2187-5219
ISSN-L : 2187-5219
Volume 1
Displaying 1-18 of 18 articles from this issue
  • Shoichi SENDA
    Article type: Foreword
    2012 Volume 1 Pages 1
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
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  • Yuichi KIMURA, Masaru SUGIMACHI, Osamu OSHIRO, Masaaki MAKIKAWA
    Article type: Foreword
    2012 Volume 1 Pages 2
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
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  • Masaki KYOSO, Jun MIDORIKAWA, Yuichi SHIMATANI
    Article type: Original Paper
    2012 Volume 1 Pages 3-8
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Many useful signals measured on the body surface contain DC and extremely low frequency components. However, surface electrodes are not ideal for DC or low frequency signal measurements because the electrochemical interaction between the body and the metal contact is unstable. We propose a substantial technique to improve DC stability for biological potential measurements on the body surface, by which unstable fluctuations are canceled by a discharging switch. The system alternates between two states. In the discharging state, two electrodes are connected to each other by an analog switch and the randomly generated charge on the electrodes is canceled. When the switch is turned off. the differential voltage is sampled and stored. The sampling frequency of the system is equal to the switching frequency because of this procedure. An experiment employing Ag/AgCl surface electrodes on human skin showed that DC shift and fluctuation were reduced to 1/4 and 1/6 or less, respectively, of the values without the canceler. Applying this technique to electrooculogram measurement, we found that absolute visual direction could be detected without major baseline drift.
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  • Kotaro YAMASUE, Hiroaki HAGIWARA, Osamu TOCHIKUBO, Chika SUGIMOTO, Ryu ...
    Article type: Original Paper
    2012 Volume 1 Pages 9-15
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Measuring core body temperature is important in the study of human body temperature regulation in daily life. We measured core body temperature continuously using an ingestible capsule sensor that has excellent ambulatory utility in daily life. Daily temperature changes, including temperature increase during and just after bathing and temperature decrease during sleep, were observed in all subjects. Temperature readings and communication quality were found to be negligibly affected by the intracorporeal position of the capsule as determined by radiography, with no significant temperature difference among positions in the stomach, the small intestine and the large intestine. However, intake of hot or cold beverages during measurement should be avoided for accurate assessment. Loss of data from inside to outside the body was 3.7± 2.5% (1.4 ± 3.8% excluding sleeping hours). The increase in data loss during sleep was due to the change in position of the receiver. A loss of 0.66 ± 0.1% was obtained by placing the receiver less than 50 cm from the navel including during sleep, except during the first ten minutes after swallow. The path loss from inside to outside the body was estimated to be less than that of the capsule endoscope.
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  • Shinya ONOGI, Yuto TAGUCHI, Yuki SUGANO, Nobuhiko SHIGEHARA, Ren KODA, ...
    Article type: Original Paper
    2012 Volume 1 Pages 16-22
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Therapeutic use of ultrasound (US) has a great potential for minimally invasive therapy. We have studied acoustic microbubble delivery for effective sonoporation and thermal therapy. To apply the techniques in vivo, a navigation system for US field positioning is indispensable. To address this issue, we have developed an intuitive navigation system using augmented reality (AR) technology. The system consists of an optical tracking device, a linear US probe, a focused US field source (US transducer) with 2.0-mm focal spot, a USB video camera, and navigation software. The probe was calibrated accurately using US probe calibration technique. Also, the transducer was calibrated using a three-dimensional sound field measurement device. Finally, the camera was calibrated using a chess board. The system we developed provides two kinds of augmented information : 1) therapeutic US field visualization on echogram, and 2) echogram plane and sound field visualization on video frame. In this study, the respective calibration accuracies were validated and microbubble trapping experiments using the focused US transducer and artificial blood vessel with 2.0-mm diameter were conducted. In the experiments, microbubbles were trapped inside the artificial blood vessel using the navigation system, implying that the focus position could be located in the blood vessel. The results demonstrated that the system we developed has adequate accuracy for microbubble control in 2.0-mm blood vessels.
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  • Takeshi MURAYAMA, Mana KAWAKAMI, Kozue MIYAMOTO, Toru EGUCHI, Mitsuhir ...
    Article type: Research Letter
    2012 Volume 1 Pages 23-26
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    In dental treatment, dental computer-aided design (CAD) and computer-aided manufacturing (CAM) systems have been introduced to assist dental technicians in fabricating dental prostheses. The fabrication process is as follows. Before fabrication, the dentist removes dental caries from a patient's tooth and prepares an abutment tooth. Next the shape of the abutment tooth is scanned by a 3-D scanner to generate a 3-D model of the abutment tooth on a computer. Then, using a CAD system, the dental technician designs a dental prosthesis that fits the abutment tooth. Finally, the dental prosthesis is fabricated using a CAM system and a machine tool. In the process of using the CAD/CAM systems, the shapes of abutment teeth sometimes cause problems such as the impossibility of fabricating a dental prosthesis. The purpose of this study was to develop a system that evaluates the appropriateness for the abutment teeth. Using 3-D models of abutment teeth, the system can examine: (1)whether a prosthesis can be fabricated using the machine tool ; and(2)whether there are undercuts on the abutment tooth. Using the system, we evaluated the abutment teeth prepared by students in our dental training school. The evaluation by the system was compared with the assessment by a teacher. The system execution and the comparison showed that the system can be used for evaluating abutment teeth.
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  • Hiroaki NATSUKAWA, Tetsuo KOBAYASHI
    Article type: Original Paper
    2012 Volume 1 Pages 27-35
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    To validate the performance of a newly developed normalized integrative functional magnetic resonance imaging-magnetoencephalography (fMRI-MEG) method and identify the temporal and spatial characteristics of multiple cortical activations preceding and following saccade execution, we used the fMRI-MEG method to measure and compare neuronal activities while subjects performed both a visually-guided saccade and an apparent motion perception task. Eight healthy subjects participated in the experiments. In the normalized integrative fMRI-MEG method, time-varying dipole moments of activated regions were reconstructed from measured MEGs. Sets of activated regions were determined from statistically analyzed fMRI data and were used as spatial constraints for the integrative fMRI-MEG method. Dynamic recurrent neural activities prior to saccade onset were successfully detected in multiple cortical areas including the V1/V2, V2/V3, frontal eye field (FEF), human middle temporal area (hMT), human medial superior temporal area (hMST), intraparietal sulcus (IPS) and ventral intraparietal area (VIP). These activities lasted for the whole duration of saccade and also showed double-peak responses ; before saccade onset and at saccade termination. These results demonstrated that our proposed normalized integrative fMRI-MEG method is able to reconstruct reasonable time courses of cortical activations commonly occurring in humans. In addition, these results suggest that the double-peak activities observed during saccade execution may be derived from the activities of saccade and fixation neurons. Moreover, repetitive activities in the V1/V2, V2/V3, MT, and MST indicate a possibility of feedforward process triggering discharge of FEF neurons.
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  • Ayako UENO, Norihiro KATAYAMA, Akihiro KARASHIMA, Mitsuyuki NAKAO
    Article type: Original Paper
    2012 Volume 1 Pages 36-42
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Since the conventional method of electrical stimulation delivered using an extracellular electrode has poor selectivity in terms of nerve fiber type, it is difficult to avoid recruiting antitarget nerve fibers. For example, recruitment of motor fibers by electrical stimulation frequently causes unpleasant symptoms such as pain sensation and numbness. Many electrical stimulation methods have been proposed to achieve nerve typespecific recruitment based on diameter dependence; however, experimental evaluations have suggested insufficient selectivity of these methods. In this study, we evaluated diameter-selective recruitment using triplecuff electrodes, which are composed of a single cathodic cuff electrode sandwiched between two anodic cuff electrodes with various anode-to-cathode distances, De. Using numerical simulations, we determined the stimulation-response characteristics as functions of stimulus intensity (IC) and fiber diameter D(1-20 µmϕ), when De values were set at infinite and 2-mm distances. We observed that thinner axons were recruited as IC increased and that the thresholds for cathodic excitation and anodal block were dependent on De. The dependence of threshold intensities for cathodic excitation and anodal block on various axon diameters at each De was analyzed. The results confirmed that thin axons had higher thresholds and that threshold intensities were nonmonotonically dependent on De. When De was set to infinite distance (corresponding to a single-cuff electrode) and IC was relatively low, only thick axons (≥10 µmϕ, e. g., Aα fiber group) were selectively recruited. By decreasing De to about 2 mm and increasing the stimulus intensity, thicker axons were suppressed by anodal block ; in contrast, thinner axons (≤10 µmϕ) became selectively recruited. It was possible to recruit either moderately thick (5-9 µmϕ, e. g., Aβ fiber group) or thin (2-4 µmϕ, e. g., Aδ fiber group) axons by scrutinizing the De and IC dependence of nerve recruitment. Axon response was robust against radial position in the nerve bundle. These results suggest that electrical stimulation using a triple-cuff electrode properly adjusted for both stimulus intensity and distance between the anodic and cathodic electrodes has the potential for nerve-specific recruitment within a nerve bundle.
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  • Yoshihiro TANGE, Heihachi MIGITA, Shigenori YOSHITAKE, Yutaka ISAKOZAW ...
    Article type: Original Paper
    2012 Volume 1 Pages 43-46
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Peripheral artery disease (PAD) is an important marker of systemic atherosclerosis, and often leads to significant morbidity and mortality, particularly in patients with end-stage renal disease. Hyperbaric oxygen therapy (HBOT) increases tissue oxygenation by administering 100% oxygen at greater than one atmosphere pressure, and has beneficial effects on hypoxic wound healing in patients with PAD. We hypothesized that increasing partial pressure of oxygen (PO2) in the blood stream during hemodialysis (HD) improves the hypoxic tissue by a different mechanism from that of HBOT. We developed a device to enhance PO2 content in the dialysate. This study examined the effects of a commercially available dialysate and a high PO2 dialysate on PO2 in blood during simulated circulation in hemodialysis (HD). Batches of 1000 ml of bovine blood were prepared. We conducted HD for 120 min at a flow rate in blood pump of 200 ml/min and dialysate flow rate of 500 ml/min. KINDALY AF-2 containing bicarbonate was used as dialysate. All the experiments were performed at 310 K. Dialysate with high PO2 content was made using a gas compressor that increased PO2 in the dialysate up to 300 mmHg after deaeration. The gas compressor was installed between the reverse osmosis (RO) water line and the dialysis machine. We conducted HD by circulating bovine blood using either the conventional dialysate as control or the high PO2 dialysate. Blood samples were collected from both the inlet and outlet of the dialyzer during HD, and pH, PO2, PCO2, HCO3- and O2 saturation were determined. PO2 in blood and conventional dialysate were 42.0 mmHg and 145 mmHg, respectively, before circulation. PO2 was always higher at the outlet than at the inlet of the dialyzer after circulation started. With conventional dialysate, PO2 in blood sample increased gradually for the first 30 min after starting the experiment and then reached a plateau at 100 to 120 mmHg. With high PO2 dialysate, PO2 showed a plateau of 240 to 260 mmHg after increasing sharply for the first 30 min, and the values were higher compared to conventional dialysate. From these results, we speculate that conventional buffer dialysate transfers oxygen from the dialysate to the blood stream, and dialysate with high PO2 content enhances oxygenation of blood during HD. This system is a promising method to transport high PO2 to peripheral tissues leading to improvement of PAD.
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  • Masahiro YAKAMI, Tomohiro KURODA, Takeshi KUBO, Yutaka EMOTO, Hiroyuki ...
    Article type: Original Paper
    2012 Volume 1 Pages 47-53
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Although hospital information systems (HIS) have recently become more widely used, data stored in HIS databases are not fully utilized in clinical research. One major reason is the lack of suitable tools to utilize the stored data for clinical research. Patient eligibility criteria for clinical studies often consist of multiple conditions incorporating logical operations across multiple data tables. These are too complex to perform using the existing HIS interfaces, which were originally designed for clinical business rather than clinical research. Moreover, these criteria sometimes require importing patient lists from external data sources not stored in the HIS databases. Certainly end-user computing (EUC) is effective in satisfying these demands, but in reality, EUC is too difficult for many clinical researchers to master because it requires them to understand the complicated composition of the data tables in the HIS database. Thus, we have developed a search system to meet these needs using user-friendly interfaces. Since the objective of a clinical study is to prove a relationship between a certain purported cause and the outcome, target patients must be selected based on several items of clinical information. Patient eligibility criteria for clinical studies are usually complex, consisting of multiple conditions combined with logical “AND”, “OR” and “NOT” operations as well as parentheses. It is a challenge to design user interfaces that can specify logical operations and parentheses among multiple search conditions. Our search system is designed to support set operations between the lists of search results as well as functions for loading and saving multiple lists, instead of logical operations and parentheses among search conditions. The system was developed using a middleware package for EUC, and was released in our institute. In this study, both the proposed search system and search interfaces for our institutional HIS were evaluated using application forms submitted to the Informatics Department requesting search and export of data stored in the HIS database. The requests were processed using both systems, and the results were recorded and analyzed for evaluation. Our search system fulfilled a significantly larger number of requests than the HIS interfaces (paired t-test, p<0.05).
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  • Hiroaki NATSUKAWA, Tetsuo KOBAYASHI
    Article type: Erratum
    2012 Volume 1 Pages 54
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
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  • Fumiyoshi MATSUSAKI, Yoshinori KATAYAMA, Keiji IRAMINA
    Article type: Original Paper
    2012 Volume 1 Pages 55-59
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Transcranial magnetic stimulation (TMS) allows non-invasive and painless stimulation of local cerebral nerves using eddy current generated by electromagnetic induction with a TMS coil. Although TMS is used in various fields, which area of the brain is stimulated is not known because of the complicated structure of the organ. In this study, we simulated neuronal excitement by TMS using the finite element method. First, we designed a brain sulcus model consisting of cerebrospinal fluid, gray matter and white matter, using 0.5 mm cube elements. To improve calculation accuracy, cube element size was set to 0.5/3 mm only in regions near the boundary surface. Second, we applied TMS stimulation to the model in different conditions. We used coil radii of 10, 20, 30 and 40 mm, and coil orientation at 0°, 30°, 45°, 60° and 90°, which is defined as the angle between the orientation of the electric field and the axon. Finally, we calculated the membrane potential and compared the results obtained under different conditions. We found that membrane potential changed rapidly at the white matter and gray matter interface when the coil radius was over 20 mm and coil orientation was within 60° between the orientation of the electric field and the axon. These results provide useful information on appropriate TMS parameters for effective stimulation of target area in the brain.
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  • Hirohisa KOTERA, Masatomo YASHIRO, Atsushi OHASHI, Toshiro KATAYAMA
    Article type: Original Paper
    2012 Volume 1 Pages 60-67
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Hepatitis C virus (HCV) viral loads are reported to be lower in HCV-positive dialysis patients than in HCV-positive non-dialysis patients. Previously, we conducted in vitro experiments of HCV reperfusion using different dialysis membranes and performed curve fitting. We revealed that adsorption of HCV antigen onto the surface of dialysis membranes could be explained by the mathematical model of Langmuir's adsorption isotherm. In the present study, we aimed at verifying the applicability of this mathematical model in clinical dialysis, by investigating the elimination dynamics of HCV antigen using the same dialysis membranes, comprising regenerated cellulose membrane (CU), cellulose triacetate membrane (CTA), polymethylmethacrylate membrane (PMMA), and polysulfone membrane (PS), in the clinical experiment. We estimated post-dialysis HCV antigen levels from measured pre-dialysis HCV antigen levels, using the mathematical model of Langmuir's adsorption isotherm. Our results confirmed high adsorption of HCV antigen with the PS membrane, and demonstrated that the correlation coefficients between measured and estimated HCV antigen levels were over 0.97 with the PS, CTA, CU membranes. These results indicated the usefulness of Langmuir's adsorption isotherm in clinical dialysis. However, HCV antigen increased again after a dialysis session until the next dialysis. Therefore, we applied the mathematical model of logistic growth to the multiplication process of HCV antigen during the inter-dialysis interval. Our results confirmed the usefulness of the logistic growth curve in describing the multiplication process of HCV antigen, and suggested that the increase in HCV antigen level during the dialysis interval was proportional to the decrease in HCV antigen level by hemodialysis therapy. In conclusion, we confirmed the usefulness of these mathematical models, and demonstrated that for each dialysis session, HCV antigen decreases and multiplies within a uniform range, which is characteristic of each dialysis membrane. The continuous multiplication of HCV antigen could be controlled, and we propose that the equilibrium of HCV antigen levels might be maintained by dialysis.
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  • Ryo TACHIKAWA, Akira TSUKAMOTO, Keiichi NAKAGAWA, Tatsuhiko ARAFUNE, H ...
    Article type: Original Paper
    2012 Volume 1 Pages 68-73
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Shock waves have recently attracted attention for their effects on biological soft tissues, such as angiogenesis. When shock waves are reflected at some surfaces of biological tissues, an expansion wave with as short duration as shock wave can be generated because of a change in acoustic impedance. We hypothesized that the expansion wave affects soft tissues, inducing bioeffects. In this study, we developed an expansion wave generator consisting of an ellipsoidal reflector and a polydimethyl siloxane (PDMS) unit. A shock wave (compression wave) was generated by underwater electric discharge and focused by reflection from an ellipsoidal mirror. The shock wave propagated in the water and was transmitted at the water-PDMS boundary surface because they have almost the same acoustic impedance (1.5 × 106 kg/m2·s for water, approximately 1.4 × 106 kg/m2·s for PDMS). Next, the shock wave was reflected at the PDMS-air boundary surface. At this surface, the shock wave was converted to an expansion wave because the acoustic impedance of PDMS is much higher than that of air (4.3 × 102 kg/m2·s). After these reflections, the expansion wave was focused. At the focal point, the peak pressure measured by a hydrophone was - 5.52 ± 1.23 MPa (n= 10) when the discharge voltage was 4 kV. Moreover, the half-width of the expansion wave was 0.55 ± 0.16 µs (n= 10). These values were the same as those of the shock wave. These results indicate that our expansion wave generator is able to produce expansion waves and is useful for studying their bioeffects.
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  • Keisuke HASHIMURA, Katsunori ISHII, Naota AKIKUSA, Tadataka EDAMURA, H ...
    Article type: Original Paper
    2012 Volume 1 Pages 74-80
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    We evaluated the potential of using a compact, high-power quantum cascade laser (QCL) in the 5.7-µm wavelength range for less-invasive laser angioplasty, by observing the effects of QCL irradiation on cholesteryl oleate thin films and a porcine thoracic aorta. We compared the results obtained using QCL with those obtained using nanosecond pulsed laser by difference-frequency generation (DFG laser) at a wavelength of 5.75 µm. The QCL irradiation melted the cholesteryl oleate thin films after irradiation for 5-30 s at an average power density of 40 W/cm2. On the other hand, the porcine thoracic aorta was not damaged after irradiation for 1-5 s at 40-50 W/cm2. This result demonstrates that QCL selectively react with cholesteryl oleate without damaging the porcine thoracic aorta. The QCL induced more thermal damage than the DFG laser under irradiation conditions that gave comparable ablation depths. This finding demonstrates the potential of achieving less-invasive, selective treatment of atherosclerotic plaques using QCL in the 5.7-µm wavelength range, although the pulse structure of the QCL requires improvement to prevent thermal damage to a normal artery.
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  • Michiro OHTSU, Yutaka FUKUOKA, Akinori UENO
    Article type: Original Paper
    2012 Volume 1 Pages 81-88
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    In this article, we propose a novel method for facilitating underwater electromyographic measurement, without using an adhesive waterproof film. This method employs a waterproofed insulated electrode and an amplifier with high-input impedance. The prototypes of the components were assembled and used for electromyographic measurement of the gastrocnemius, tibialis anterior, and long fibular muscles during plantar flexion both in and out of water. Eight subjects participated in the experiment. For each measurement site, the integrated underwater electromyography (EMG) was compared with that performed out of water, and the attenuation rate was then calculated. The results showed that( 1 )the mean attenuation rate of underwater EMG among the eight subjects was -1.58%, and( 2 )depending on the conditions, only two or three subjects showed significant attenuation at any of the three sites. In contrast, when non-waterproofed, disposable electrodes and a commercially available amplifier were used for electromyographic measurement, all eight subjects showed significant attenuation in underwater EMG at all three sites, with a mean attenuation rate of 80.5%. These results indicate that the proposed method is promising for underwater electromyographic measurement. In addition, it requires no waterproofing preparations, which might cause skin irritation and/or damage, thus allowing easier setup.
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  • Shunsuke YOSHIMOTO, Yoshihiro KURODA, Masataka IMURA, Osamu OSHIRO
    Article type: Original Paper
    2012 Volume 1 Pages 89-97
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Because touch is a mechanical interaction between the skin and an object, unconstrained tactile sensing is a challenging issue. In this research we studied spatial transparency, a new concept in unconstrained tactile sensing that allows collection of tactile information without affecting the touch conditions. Especially, we aimed at developing a spatially transparent tactile sensor that detects touch information with high dynamic range from any part of the body. For the development of such sensors, this report focuses on the electromechanical properties of the skin, particularly elasticity and conductivity, and proposes a novel tactile sensor based on measurement of the electrical contact impedance between the skin and an object. The measurement of skin contact impedance is achieved using a grounding electrode and two signal electrodes attached to any part of the body. We investigated the relationship between touch force and output of the proposed sensor using a force sensor. The experimental results indicate that the proposed sensor functions adequately as an unconstrained tactile sensor, and confirm that the proposed sensing system has an excellent dynamic range.
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  • Tohru F. YAMAGUCHI, Mitsuhiro KATASHIMA, Li-Qun WANG, Shinya KURIKI
    Article type: Original Paper
    2012 Volume 1 Pages 98-106
    Published: 2012
    Released on J-STAGE: June 28, 2013
    JOURNAL FREE ACCESS
    Electrical impedance tomography (EIT) is expected to be used in image reconstruction of accumulated visceral fat in the human abdomen, where the accumulated visceral fat may be related to a risk of metabolic syndrome. This work aimed to study the effects of the anisotropy of bioelectrical conductivity on image reconstruction by EIT of human abdominal cross-section. We developed a tomography device with 64 electrodes arranged in upper and lower rings surrounding the subject's abdomen at the umbilical level. An alternating current of 1.0 mArms at a frequency of 500 kHz was applied through two adjacent electrodes in the upper ring, and the potential difference between every adjacent pair of electrodes in the lower ring was measured. From these voltage data, the cross-section of the abdominal conductivity was imaged by iterative calculations using the finite element method and nonlinear numeric optimization. When we considered the conductivity anisotropy in both transverse and longitudinal directions, the conductivity values obtained were within the physiologically plausible range reported in the literature. On the other hand, when the conductivity anisotropy was neglected, the central part of the image had extraordinarily low conductivity, and was outside the physiological range. The need to consider the anisotropic conductivity in image reconstruction was further confirmed by significantly reduced residual squared error in the optimization calculation.
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