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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Biomedical Engineering Research
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Journal DOI :
The Korea Society of Medical and Biological Engineering
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Volume & Issues
Volume 29, Issue 6 - Dec 2008
Volume 29, Issue 5 - Oct 2008
Volume 29, Issue 4 - Aug 2008
Volume 29, Issue 3 - Jun 2008
Volume 29, Issue 2 - Apr 2008
Volume 29, Issue 1 - Feb 2008
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Medical Applications of Near Infrared Spectroscopy and Diffuse Optical Imaging (Review)
Lee, Seung-Duk ; Kwon, Ki-Won ; Koh, Dal-Kwon ; Kim, Beop-Min ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 89~98
NIRS (Near-infrared Spectroscopy) and DOI (Diffuse Optical Imaging) are relatively new, non-invasive, and non-ionizing methods that measure or image optical properties (Scattering and Absorption Coefficient) and physiological properties (Water Fraction, concentration of Oxy-, Deoxy-Hemoglobin, Cytochrome Oxidase, etc) of biological tissues. In this paper, three different types of NIRS systems, mathematical modeling, and reconstruction algorithms are described. Also, recent applications such as functional brain imaging, optical mammography, NIRS based BMI (Brain-Machine Interface), and small animal study are reviewed.
Time-Multiplexed RF Transmission to Improve
Homogeneity in High Field MRI
Han, Byung-Hee ; Seo, Jeung-Hun ; Heo, Hye-Young ; Lee, Soo-Yeol ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 99~106
homogeneity in high field MRI, the RF power is applied to the transmit array coil elements sequentially in the time-multiplexed way. Since only a single coil element is activated in a time-multiplexing slot, the global standing wave formation in the human body is greatly suppressed. The time-multiplexing slot width is on the order of micro seconds, hence, high-order-harmonic slices can be placed far from the transmit coil and simultaneous multiple slice selection can be avoided. The
homogeneities of a birdcage coil and an eight-channel transmit array coil have been compared through finite difference time domain simulations. The simulation results indicate that the proposed technique can reduce the peak-to-peak
inhomogeneity down to one fourth of the transmission with a birdcage coil on the central plane of the human head model at 3 T. The mimicking experiments at 3 T, eight separate experiments with a single coil element activated and image reconstruction by combining the eight images, also show promising results. It is expected that the proposed technique has some advantages over other
improving methods in real practice since simple RF switching circuitries are only necessary and electromagnetic coupling between the coil elements is out of concern in its realization.
Rotating-Gantry-Based X-Ray Micro-Tomography System with the Sliding Mechanism Capable of Zoom-In Imaging
Cho, Min-Hyoung ; Lee, Dong-Hun ; Han, Byung-Hee ; Lee, Soo-Yeol ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 107~113
We introduce a rotating-gantry-based x-ray micro-tomography system to be used for small animal imaging studies. It has the zoom-in imaging capability for high resolution imaging of a local region inside the animal subject without any contrast anomalies arising from truncation of the projection data. With the sliding mechanism mounted on the rotating gantry holding the x-ray source and the x-ray detector, we can control the magnification ratio of the x-ray projection data. By combining the projection data from the large field of view (FOV) scan of the whole animal subject and the projection data from the small FOV scan of the region of interest, we can obtain artifact-free zoomed-in images of the region of interest. For the acquisition of x-ray projection data, we use a
flat-panel x-ray detector with the pixel pitch of 100 mm. It has been experimentally found that the developed system has the spatial resolution of up to 121p/mm when the highest magnification ratio of 5:1 is applied to the zoom-in imaging. We present some in vivo rat femur images to demonstrate utility of the developed system for small animal imaging.
Applications of Diffusion Tensor MRI to Predict Motor Recovery of Stroke Patients in the Chronic Stages
Tae, Ki-Sik ; Song, Sung-Jae ; Kim, Young-Ho ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 114~121
Within 2 to 5 months after stroke, patients recover variable degrees of function, depending on the initial deficit. An impaired hand function is one of the most serious disability in chronic stroke patients. Therefore, to evaluate the extent of motor dysfunction in the hemiplegic hand is important in stroke rehabilitation. In this paper, motor recoveries in 8 chronic stroke patients with Fugl-Meyer (FM) and white matter changes before and after the training program with a designed bilateral symmetrical arm trainer (BSAT) system were examined. The training was performed at 1 hr/day, 5 days/week during 6weeks. In all patients, FM was significantly improved after the 6-week training. Diffusion tensor imaging (DTI) results showed that tractional anisotropy ratio (FAR) and fiber tracking ratio (FTR) in the posterior internal capsule were significantly increased after the training. It seemed that the cortical reorganization was induced by the 6 week training with the BSAT. In all parameters proposed this study, a significant correlation was found between these parameters (FAR and FTR) and motor recoveries. This study demonstrated that DTI technique could be useful in predicting motor recovery in chronic hemiparetic patients.
Speckle Noise Reduction and Edge Enhancement in Ultrasound Images Based on Wavelet Transform
Kim, Yong-Sun ; Ra, Jong-Beom ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 122~131
For B-mode ultrasound images, we propose an image enhancement algorithm based on a multi-resolution approach, which consists of edge enhancing and noise reducing procedures. Edge enhancement processing is applied sequentially to coarse-to-fine resolution images obtained from wavelet-transformed data. In each resolution, the structural features of each pixel are examined through eigen analysis. Then, if a pixel belongs to an edge region, we perform two-step filtering: that is, directional smoothing is conducted along the tangential direction of the edge to improve continuity and directional sharpening is conducted along the normal direction to enhance the contrast. In addition, speckle noise is alleviated by proper attenuation of the wavelet coefficients of the homogeneous regions at each band. This region-based speckle-reduction scheme is differentiated from other methods that are based on the magnitude statistics of the wavelet coefficients. The proposed algorithm enhances edges regardless of changes in the resolution of an image, and the algorithm efficiently reduces speckle noise without affecting the sharpness of the edge. Hence, compared with existing algorithms, the proposed algorithm considerably improves the subjective image quality without providing any noticeable artifacts.
Development of an ACL Anchor: Effects of the Design Parameters on the Performance of a New Anterior Cruciate Ligament Fixation Device
Kim, Jong-Dae ; Oh, Chae-Youn ; Kim, Cheol-Sang ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 132~138
We investigated the biomechanical properties of a newly designed self-expansion type anterior cruciate ligament (ACL) anchor. The ACL anchor consists of the ring section giving the elastic force, the wedge for maintaining in contact with the femur tunnel wall and the link suspending hamstring graft or artificial ligament. The main design parameters that determine the performance of this device were the expansion angle (
) and the thickness (
). The Ti6Al4V anchors were heated after inserting in a jig for 1 hour at
in a protective argon gas atmosphere and allowed to cool to room temperature in the furnace. In order to investigate the influence of the expansion angle and the thickness of the ring on the biomechanical properties of the anchor, the maximum pull-out load, stiffness and slippage of the ACL anchor were measured using the pull-out tester, and statistical analyses were also executed. The present results showed that the design parameters gave a significant effect on the performance of the self- expansion type of anchor. The pull-out load of the ACL anchors significantly increased as the thickness of the ring section was increased, having a similar trend for both expansion angles. The ACL anchor showed about 2.5 times higher values of the pull-out load than that of the minimum load (500N)required for the "accelerated rehabilitation". The optimum
values of this ACL anchor were suggested to have sufficient resistance against the pull-out force, high stiffness and relatively low slippage after ACL reconstruction.
Biomechanical Effects of Posterior Dynamic Stabilization System on Lumbar Kinematics: A Finite Element Analysis
Ahn, Y.H. ; Chen, Wen-Ming ; Jung, D.Y. ; Park, K.W. ; Lee, S.J. ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 139~145
Many recent studies suggest that the posterior dynamic stabilization(PDS) can be a more physiologically-relevant alternative to the rigid fixation for the patients suffering from low back pain. However, its biomechanical effects or clinically proven efficacies still remain unknown. In this study, we evaluated kinematic behaviors of the lower lumbar spine with the PDS system and then compared to those of the rigid fixation system using finite element (FE) analysis. A validated FE model of intact lumbar spine(L2-L5) was developed. The implanted model was then constructed after modification from the intact to simulate two kinds of pedicle screw systems (PDS and the rigid fixation). Hybrid protocol was used to flex, extend, laterally bend and axially rotate the FE model. Results showed that the PDS systems are more flexible than rigid fixation systems, yet not flexible enough to preserve motion. PDS system allowed
more intersegmental rotation than the rigid fixation at the implanted level. One the other hand, at the adjacent level it allowed more range of motion (
) than the rigid fixation. The center of rotation of the PDS model remained closer to that of the intact spine. These results suggest that the PDS system could be able to prevent excessive motion at the adjacent levels and restore the spinal kinematics.
Reconstruction of 3D Brain Model using Curvature Information
An, Kwang-Ok ; Jung, Hyun-Kyo ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 146~150
In order to study cortical properties in human, it is necessary to obtain an accurate and explicit representation of the cortical surface in individual subjects. Among many approaches, surface-based method that reconstructs a 3-D model from contour lines on cross-section images is widely used. The conventional method detects match points of contours using the minimum straight distance between any pair of contour points which lie on different contours. Then, it generates a triangle strip. In general, however, it might yield small mismatches between contours in case of brain due to complex anatomical structures. In this paper, therefore, we present an improved method for tilting operation that uses the curvature values calculated from surface information. The usefulness of the proposed method has been verified using brain image.
A suggestion of Aortic wall Stiffness Evaluation Technique Independent on Changeable Blood Pressure : Aortic Distensibility Index
Seo, Jee-Hye ; Choi, Dong-Ho ; Wu, Zhuqing ; Rienmueller, Rainer ; Lee, Jong-Min ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 151~158
To evaluate aortic wall stiffness without influence of different background blood pressure, a new technique was developed and verified. At eight swine descending aortae, volume-pressure measurement was performed using custom-made system. Based on averaged pressure-volume curve, aortic distensibility index was formulated to evaluate aortic wall stiffness regardless of variable blood pressure and aortic size. The variability of aortic distensibility index by pressure change was compared with other parameters for wall stiffness evaluation. Subsequently, the aortic distensibility index was calculated at 100 contrast-enhanced EBCT data sets of normal volunteers in regular health screening program. The measured aortic distensibility index was compared with age, coronary calcium score, and aortic calcium score. Between 50 and 360 mmHg of blood pressure, the coefficient of variance of aortic distensibility index was 22.00% as comparing with 88.99% of classical compliance. Based on age, aortic distensibility index showed correlation coefficient of 0.55, whereas classical compliance showed 0.26. The correlation coefficient with modified aortic calcification was 0.43. Linear regression study revealed statistical significance of correlation coefficients. The aortic distensibility index, the method to evaluate aortic wall stiffness free from variable blood pressure and aortic size, was developed and verified with significant practical feasibility.
The Differentiation of bone Marrow Stromal Cells into NP-like Cells through 3-Dimensional Co-culture System
Kim, D.H. ; Kim, S.H. ; Heo, S.J. ; Shin, J.W. ; Kim, Y.J. ; Park, S.H. ; Jun, J.W. ; Shin, J.W. ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 159~163
The goal of this study is to investigate the effect and potential of three-dimensional Co-culture of BMSCs (bone marrow stromal Cells) and NP (nucleus pulposus) Cells on the differentiation of BMSCs into NP-like Cells. The NP Cells and BMSCs were isolated and cultured from New Zealand White rabbits. The isolated NP Cells and BMSCs were prepared in different alginate beads. Those two types of beads were separated by a track-etched membrane of
pore in a 6-well culture plate. No growth factors were used. In addition to these, NP and BMSC were cultured in the beads independently for control. The number of Cells in Co-culturing system was half of those in two control groups. Proliferation and production of glycosaminoglycan (GAG) were evaluated along with histological observation. The GAG production rate(GAG contents/Cell) of Co-cultured BMSCs were much higher than that of BMSCs cultured alone. The total amounts of GAG produced by BMSCs in Co-culturing system were larger than those produced by BMSCs in control group and were comparable with those produced by NP alone even the number of each Cell was half of BMSCs in Co-culturing system. This study showed the potential of differentiation of BMSCs into NP-like Cells through three-dimensional Co-culture system even without any chemical agents.
Waveform Biosignal Interface based on International Standard MEER
Cho, Hune ; Kim, Seon-Chil ;
Journal of Biomedical Engineering Research, volume 29, issue 2, 2008, Pages 164~171
Recently, many of hospitals have hurried to computerize the resulting data from medical devices, in order to introduce Electric Medical Record(EMR). In terms of the linkage between medical devices and hospital information systems, however, many difficulties have arisen due to some reasons such as the variety of prescription input, the format difference of the resulting data sheet, and the interface difference between medical devices from different companies. To solve these problems, many researches on standardization of the resulting data of medical devices have been performed. In this study, the linkage between hospital information systems and resulting datum in Electrocardiogram(ECG) generating biosignal waveform was tested by applying Medical waveform Format Encoding Rules(MFER) Version 1.02, which has more advantages than existing global standard. MFER viewer, in addition, was made to display the resulting data on a screen. The MFER viewer was tested and compared to the existing Scalable Vector Graphics (SVG) Viewer. The results showed that this method is more effective in the interface the data storage and application, because of simplicity and easiness in data applications. And the results show that the MFER is convenience and effective for physician. It is considered that the role of MFER as the interface in biosignal waveform including Electrocardiogram medical devices would expand in the near future.