Kwon-Ha Yoon

Wonkwang University School of Medicine and Hospital, Riri, North Jeolla, South Korea

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Publications (68)134.17 Total impact

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    ABSTRACT: The aim of our study was to assess the hemodynamic change of liver during the Valsalva maneuver using Doppler ultrasonography.
    Ultrasonography (Seoul, Korea). 08/2014;
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    ABSTRACT: Pemetrexed is a multitarget antifolate currently used for the treatment of malignant mesothelioma and non-small cell lung cancer (NSCLC). Statins, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors used primarily for hyperlidpidemia, have been studied for their antiproliferative and pro-apoptotic effects. However, the effects of simvastatin on pemetrexed-induced apoptosis have not been investigated. In this study, we investigated whether combination treatment with pemetrexed and simvastatin potentiates the apoptotic activity above that is seen with either drug alone in malignant mesothelioma and NSCLC cells. We found that the combination of pemetrexed and simvastatin induced more extensive caspase-dependent apoptosis than either drug alone in malignant mesothelioma cells (MSTO-211) or NSCLC cells (A549). In addition, reactive oxygen species (ROS) generation in cells treated with both pemetrexed and simvastatin was markedly increased compared to cells treated with either pemetrexed or simvastatin alone. Combination treatment also increased the loss of mitochondrial membrane potential, increased cytosolic release of cytochrome c, and altered expression of inhibitor of apoptosis proteins (IAP) and B-cell lymphoma-2 (Bcl-2) families of apoptosis related proteins. On the other hand, pretreatment with N-acetylcysteine (NAC) prevented apoptosis and mitochondrial dysfunction by pemetrexed and simvastatin. In addition, Bim siRNA conferred protection against apoptosis induced by pemetrexed and simvastatin. These results suggest that combination of pemetrexed and simvastatin potentiates their apoptotic activity beyond that of either drug alone in malignant mesothelioma and lung cancer cells. This activity is mediated through ROS-dependent mitochondrial dysfunction and Bim induction.
    International journal of oncology. 08/2014;
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    ABSTRACT: Rationale and Objectives To identify micro–computed tomography (CT) imaging biomarkers for evaluating the effects of emodin, a potential drug to treat osteoporosis, in the mouse model of lipopolysaccharide (LPS)-mediated osteoporosis. Materials and Methods Forty male imprinting control region (ICR) mice with LPS-induced bone resorption were equally divided into four experimental groups: phosphate-buffered saline–treated (control), emodin-treated, LPS-treated, and LPS + emodin–treated groups. Emodin (50 mg/kg) was administered orally on alternate days for 8 days, and LPS (5 mg/kg) was injected intraperitoneally on days 1 and 4. After 8 days, the mice were sacrificed, and micro-CT images of the left proximal femurs were obtained. Three-dimensional images were analyzed by using commercial software to measure the bone volume to total volume fraction (BV/TV), trabecular number (Tb-N), trabecular thickness (Tb-Th), and trabecular separation (Tb-Sp) as CT imaging biomarkers. Histologic analyses of the femurs were performed using hematoxylin and eosin and tartrate-resistant acid phosphatase (TRAP) immunohistochemical staining. Results The LPS + emodin–treated group demonstrated marked suppression of LPS-induced bone resorption compared to the LPS-treated group (BV/TV, 28.84% vs. 40.76%; Tb-N, 2.65 vs. 3.45 mm−1; Tb-Sp, 300.81 vs. 212.31 μm; Tb-Th, 116.94 vs. 131.25 μm). TRAP immunohistochemical analysis showed fewer osteoclasts per field of tissue in the LPS + emodin–treated group than in the LPS-treated group (27.8 vs. 41.8). The BV/TV, Tb-N, and Tb-Sp data correlated well with the histomorphometric findings. Conclusions The findings reveal a novel effect of emodin on bone remodeling in the LPS-mediated osteoporotic mouse model. The ex vivo micro-CT imaging is a promising tool for assessing the therapeutic effects of potential drugs on osteoporosis.
    Academic radiology 04/2014; 21(4):457–462. · 2.09 Impact Factor
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    ABSTRACT: Recently, natural plant-derived products have been recognized as one of the main sources for drug discovery and development in human disease. 9-Hydroxy-6,7-dimethoxydalbergiquinol (HDDQ) isolated from the heart wood of Dalbergia odorifera is widely used in oriental medicine, however, the pharmacological effect of HDDQ in osteoclast-associated diseases remains unknown. In this study, HDDQ dose-dependently inhibited the early stage of RANKL-mediated osteoclast differentiation in bone marrow macrophages (BMMs) without cytotoxicity. HDDQ strongly inhibited Akt phosphorylation in RANKL-stimulated BMMs and did not show any effects on p38, JNK, and IκB phosphorylation and IκB degradation. Interestingly, we found that HDDQ down-regulated the induction by RANKL of c-Fos protein by suppressing its translation. Also, ectopic overexpression of c-Fos and NFATc1 rescued the inhibition of osteoclast differentiation by HDDQ. Furthermore, the Akt/c-Fos/NFATc1-regulated expression of genes required for osteoclastogenesis, such as OSCAR and TRAP, was inhibited by HDDQ. These findings suggest that HDDQ prevents osteoclast differentiation via down-regulation of Akt, c-Fos, and NFATc1 signaling molecules, suggesting a potential therapeutic value of HDDQ for bone disorders associated with increased bone resorption.
    International immunopharmacology 03/2014; · 2.21 Impact Factor
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    ABSTRACT: The current technologies that trend in digital radiology (DR) are toward systems using portable smart mobile as patient-centered care. We aimed to develop a mini-mobile DR system by using smart devices for wireless connection into medical information systems. We developed a mini-mobile DR system consisting of an X-ray source and a Complementary Metal-Oxide Semiconductor (CMOS) sensor based on a flat panel detector for small-field diagnostics in patients. It is used instead of the systems that are difficult to perform with a fixed traditional device. We also designed a method for embedded systems in the development of portable DR systems. The external interface used the fast and stable IEEE 802.11n wireless protocol, and we adapted the device for connections with Picture Archiving and Communication System (PACS) and smart devices. The smart device could display images on an external monitor other than the monitor in the DR system. The communication modules, main control board, and external interface supporting smart devices were implemented. Further, a smart viewer based on the external interface was developed to display image files on various smart devices. In addition, the advantage of operators is to reduce radiation dose when using remote smart devices. It is integrated with smart devices that can provide X-ray imaging services anywhere. With this technology, it can permit image observation on a smart device from a remote location by connecting to the external interface. We evaluated the response time of the mini-mobile DR system to compare to mobile PACS. The experimental results show that our system outperforms conventional mobile PACS in this regard.
    Journal of Digital Imaging 02/2014; · 1.10 Impact Factor
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    ABSTRACT: Aconitum pseudo-laeve var. erectum (APE) has been widely shown in herbal medicine to have a therapeutic effect on inflammatory conditions. However, there has been no evidence on whether the extract of APE is involved in the biological bone metabolism process, particularly osteoclast-mediated bone resorption. In this study, we confirmed that the administration of APE could restore normal skeletal conditions in a murine model of lipopolysaccharide (LPS)-induced bone loss via a decrease in the receptor activator of nuclear factor kappa-B ligand (RANKL)/osteoprotegerin (OPG) ratio and osteoclast number. We then investigated the effect of APE on the RANKL-induced formation and function of osteoclasts to elucidate its underlying molecular mechanisms. APE suppressed the formation of tartrate-resistant acid phosphatase (TRAP)-positive cells, as well as the bone-resorbing activity of mature osteoclasts. Furthermore, APE attenuated nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) and c-Fos without affecting any early signal pathway of osteoclastogenesis. Subsequently, APE significantly downregulated the expression of various genes exclusively expressed in osteoclasts. These results demonstrate that APE restores LPS-induced bone loss through a decrease of the serum RANKL/OPG ratio, and inhibits osteoclast differentiation and function, suggesting the promise of APE as a potential cure for various osteoclast-associated bone diseases.
    Molecules (Basel, Switzerland). 01/2014; 19(8):11628-44.
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    ABSTRACT: People over the age of 50 are at risk of osteoporotic fracture, which may lead to increased morbidity and mortality. Osteoclasts are responsible for bone resorption in bone-related disorders. Genipin is a well-known geniposide aglycon derived from Gardenia jasminoides, which has long been used in oriental medicine for controlling diverse conditions such as inflammation and infection. We aimed to evaluate the effects of genipin on RANKL-induced osteoclast differentiation and its mechanism of action. Genipin dose-dependently inhibited early stage RANKL-induced osteoclast differentiation in bone marrow macrophages (BMMs) during culture. Genipin inhibited RANKL-induced IκB degradation and suppressed the mRNA expression of osteoclastic markers such as NFATc1, TRAP, and OSCAR in RANKL-treated BMMs, but did not affect c-Fos mRNA expression. Interestingly, genipin markedly inhibited c-Fos protein expression in BMMs, which was reversed in the presence of the proteosome inhibitor MG-132. Furthermore, genipin inhibited RANKL-mediated osteoclast differentiation, which was also rescued by overexpression of c-Fos and NFATc1 in BMMs. Taken together, our findings indicate that genipin down-regulated RANKL-induced osteoclast differentiation through inhibition of c-Fos protein proteolysis as well as inhibition of IκB degradation. Our findings indicate that genipin could be a useful drug candidate that lacks toxic side effects for the treatment of osteoporosis.
    Journal of Pharmacological Sciences 01/2014; 124(3):344-53. · 2.15 Impact Factor
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    ABSTRACT: Although non-small cell lung cancer (NSCLC) tumors with activating mutations in the epidermal growth factor receptor (EGFR) are highly responsive to EGFR tyrosine kinase inhibitors (TKIs) including gefitinib and erlotinib, development of acquired resistance is almost inevitable. Statins show antitumor activity, but it is unknown whether they can reverse EGFR-TKIs resistance in NSCLC with the T790M mutation of EGFR. This study investigated overcoming resistance to EGFR-TKI using simvastatin. We demonstrated that addition of simvastatin to gefitinib enhanced caspase-dependent apoptosis in T790M mutant NSCLC cells. Simvastatin also strongly inhibited AKT activation, leading to suppression of β-catenin activity and the expression of its targets, survivin and cyclin D1. Both insulin treatment and AKT overexpression markedly increased p-β-catenin and survivin levels, even in the presence of gefitinib and simvastatin. However, inhibition of AKT by siRNA or LY294002 treatment decreased p-β-catenin and survivin levels. To determine the role of survivin in simvastatin-induced apoptosis of gefitinib-resistant NSCLC, we showed that the proportion of apoptotic cells following treatment with survivin siRNA and the gefitinib–simvastatin combination was greater than the theoretical additive effects, whereas survivin up-regulation could confer protection against gefitinib and simvastatin-induced apoptosis. Similar results were obtained in erlotinib and simvastatin-treated HCC827/ER cells. These findings suggest that survivin is a key molecule that renders T790M mutant NSCLC cells resistant to apoptosis induced by EGFR-TKIs and simvastatin. Overall, these data indicate that simvastatin may overcome EGFR-TKI resistance in T790M mutant NSCLCs via an AKT/β-catenin signaling-dependent down-regulation of survivin and apoptosis induction.
    Experimental Cell Research 01/2014; · 3.56 Impact Factor
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    ABSTRACT: Owing to their potential pharmacological activities in human disease, natural plant-derived compounds have recently become the focus of increased research interest. In this study, we first isolated oleanolic acid acetate (OAA), a triterpenoid compound, from Vigna angularis (azuki bean) to discover anti-bone resorptive agents. Many studies have identified and described the various medicinal effects of V. angularis extract. However, the pharmacological effect of OAA-derived V. angularis extract, particularly the effect on osteoclastogenesis, is not known. Therefore, we investigated the effect and mechanism of OAA in receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. OAA inhibited RANKL-induced osteoclast differentiation in bone marrow macrophages (BMMs) without any evidence of cytotoxicity. Interestingly, OAA significantly inhibited Btk phosphorylation, phospholipase Cγ2 (PLCγ2) phosphorylation, calcium ion (Ca(2+)) oscillation, and nuclear factor of activated T cell c1 (NFATc1) expression in RANKL-stimulated BMMs, but did not affect RANKL-induced mitogen-activated protein kinase. OAA also inhibited the bone-resorbing activity of mature osteoclasts. Furthermore, mice treated with OAA demonstrated marked attenuation of lipopolysaccharide-induced bone erosion based on micro-computed tomography and histologic analysis of femurs. Taken together, the results suggested that OAA inhibited RANKL-mediated osteoclastogenesis via PLCγ2-Ca(2+)-NFATc1 signaling in vitro and suppressed inflammatory bone loss in vivo.
    Bone 12/2013; · 4.46 Impact Factor
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    ABSTRACT: Parthenolide, a natural product derived from Feverfew, prevents septic shock and inflammation. We aimed to identify effects of parthenolide on RANKL (receptor activator of NF-κB ligand)-induced differentiation and bone resorbing activity of osteoclasts. In this study, parthenolide dose-dependently inhibited RANKL-mediated osteoclast differentiation in BMMs without any evidence of cytotoxicity and the phosphorylation of p38, ERK, and IκB as well as IκB degradation by RANKL treatment. Parthenolide suppressed the expression of NFATc1, OSCAR, TRAP, DC-STAMP, and cathepsin K in RANKL-treated BMMs. Furthermore, parthenolide down regulated the stability of c-Fos protein, but could not suppress the expression of c-Fos. Overexpression of NFATc1 and c-Fos in BMMs reversed the inhibitory effect of parthenolide on RANKL-mediated osteoclast differentiation. Parthenolide also inhibited the bone resorbing activity of mature osteoclasts. Parthenolide inhibits differentiation and bone-resolving activity of osteoclast by RANKL, suggesting its potential therapeutic value for bone destructive disorders associated with osteoclast-mediated bone resorbing.
    BMB reports 12/2013; · 1.63 Impact Factor
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    ABSTRACT: Lung cancer remains the leading cause of cancer mortality worldwide. Despite their poor prognosis, patients with lung cancer are increasingly being admitted to the medical intensive care unit (MICU) for treatment of critical illnesses. The aim of this study was to assess the outcome of patients with lung cancer who are admitted to an MICU and to identify the measurable predictors of their MICU outcome. We conducted retrospective analysis on 97 patients with lung cancer admitted to the MICU between 2007 and 2011. The mean age ± standard deviation was 71.8 ± 6.8 years. Of the 97 patients (82 male), 73 patients (75%) had non-small cell lung cancer stage IIIB, IV and 24 patients (25%) had small cell lung cancer. The intensive care unit mortality and in-hospital mortality rates were 53.6 and 61.8%. The main reasons for MICU admission were pneumonia (n = 51) and complication of cancer management (n = 45). The predictors of poor MICU outcome were history of diabetes mellitus (P = 0.028), Acute Physiology and Chronic Health Evaluation II score (P = 0.018), need for mechanical ventilation (P = 0.014), use of vasoactive agents (P < 0.0001), the presence of acute renal failure (P < 0.0001) and presence of multiorgan failure (P < 0.0001). We found that in-hospital mortality was not influenced by age, sex or performance status score of patients with lung cancer but increased with the severity of organ failure at MICU admission.
    Asia-Pacific Journal of Clinical Oncology 12/2013; · 0.91 Impact Factor
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    ABSTRACT: PURPOSE The cone-beam based volumetric CT is popularly applied to micro CT and dental CT. However, it is difficult to obtain human brain image of good quality because of various limitations such as artifacts when using volumetric CT with flat panel detector (FPD). We studied this work to develop a dedicated mobile volumetric CT with FPD for human brain imaging. METHOD AND MATERIALS Cone beam x-ray source, flat-panel detector with CMOS sensor (290.8x229.8mm), embedded PC and GPU were used in this system (Fig 1). Under the x-ray source condition of 120kV and 6mA, 360 projections were grabbed at the rate of 70 frames per seconds during 5.14 seconds for optimized human brain imaging. FOV was designed 200mm(XY) x 160mm(Z) and voxel size was 200μm in 10243. Interface for 2D image acquisition from FPD was CAMLINK(2cable,80MHz) and it can grab 70 frames per second at 2 binning. Feldkamp back-projection algorithm was used as the base for image reconstruction, and it was used S/W filtering to sinogram for artifact reduction. Reconstruction time was less than 90 seconds for 512 cube. The CT images were obtained using a head phantom (Angiographic CT head phantom ACS, Herago®, Japan). In addition modulation transfer function (MTF) and radiation dose were measured for the evaluation. RESULTS Using this dedicated brain volumetric CT, we could get a brain images using a head phantom with good quality. It was confirmed that artifact was reduced by S/W filtering to sinogram at image reconstruction. Based on the MTF (Modulation Transfer Function, 10%) curve, we found 20~21 lp/cm using phantom (QRM-ConeBeam, QRM GmbH, Germany) at 1024 cube. The CT images demonstrated cross sections through a reconstruction of a human head obtained with the soft tissue protocol. Various brain structures are clearly distinguishable, proving the improved contrast resolution of the system (Fig. 2). Images showed a little ring or scatter artifacts. The effective dose for this head scan was estimated to be about 1mSv. CONCLUSION We developed a dedicated mobile volumetric CT for brain images using cone beam x-ray and flat panel detector. This system would be perfectly suitable for intra-operative imaging and mobile imaging applications such as neurosurgery or imaging of immobilized intensive care patients. CLINICAL RELEVANCE/APPLICATION N/A
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: Costunolide, a sesquiterpene lactone, exhibits anti-inflammatory and anti-oxidant properties and mediates apoptosis. However, its effects and mechanism of action in osteoclasts remain unknown. Herein, we found that costunolide significantly inhibited RANKL-induced BMM differentiation into osteoclasts in a dose-dependent manner without affecting cytotoxicity. Costunolide did not regulate the early signaling pathways of RANKL, including the mitogen-activated protein kinase and NF-κB pathways. However, costunolide suppressed nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) expression via inhibition of c-Fos transcriptional activity without affecting RANKL-induced c-Fos expression. The inhibitory effects of costunolide were rescued by overexpression of constitutively active (CA)-NFATc1. Taken together, our results suggest that costunolide inhibited RANKL-induced osteoclast differentiation by suppressing RANKL-mediated c-Fos transcriptional activity. Copyright © 2013 John Wiley & Sons, Ltd.
    Phytotherapy Research 07/2013; · 2.40 Impact Factor
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    ABSTRACT: Prevention of lung cancer is more feasible and holds greater promise when different agents are used in combination to target multiple processes during carcinogenesis. The mechanisms by which non-steroidal anti-inflammatory drugs and statins inhibit cancer cell growth and induce apoptosis are not fully understood. This study was designed to investigate lung cancer chemoprevention through a mechanism-based approach using sulindac at low doses in combination with simvastatin. We found that sulindac-induced cytotoxicity was significantly enhanced in the presence of simvastatin. The combination of sulindac and simvastatin induced more extensive caspase-dependent apoptosis in A549 cells compared to that induced with either drug alone. The combination of sulindac and simvastatin also increased the loss of mitochondrial transmembrane potential (∆Ψm) and the cytosolic release of cytochrome c. In addition, ROS generation in cells treated with both sulindac and simvastatin was markedly increased compared to cells treated with either sulindac or simvastatin alone. The enhancement of ROS generation by sulindac and simvastatin was abrogated by pretreatment with NAC, which also prevented apoptosis and mitochondrial dysfunction induced by sulindac and simvastatin. These results suggest that sulindac and simvastatin-induced ROS generation in A549 lung cancer cells causes their accumulation in mitochondria, triggering the release of apoptogenic molecules from the mitochondria to the cytosol, and thus leading to caspase activation and cell death.
    International Journal of Oncology 05/2013; · 2.66 Impact Factor
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    ABSTRACT: The expression levels of Prx1 are frequently elevated in several human cancers, including lung cancer and may confer increased resistance to treatment. In this study, we investigated the role of Prx1 in docetaxel-induced apoptosis in A549 lung cancer cells. To test whether Prx1 knockdown affected the sensitivity of A549 cells to docetaxel treatment, we generated short hairpin RNA (shRNA) constructs targeting Prx1 and analyzed the effect of Prx1 knockdown on growth and apoptosis. Tumor growth was evaluated in scrambled shRNA- or shPrx1-infected A549 cell tumors receiving docetaxel treatment. In addition, mechanistic information was gathered by western blot analysis from cell lysates of scrambled- and shPrx1-infected A549 cells pretreated with or without LY294002 and subsequently treated with docetaxel. We found that Prx1 knockdown resulted in enhanced docetaxel-induced cytotoxicity in a dose-dependent manner. In vivo, the growth rate of shPrx1-infected A549 tumors was significantly reduced compared to that of scrambled shRNA-infected A549 tumors. Prx1 knockdown also augmented the inhibitory effects of docetaxel on tumor growth. Prx1 knockdown increased the apoptotic potential through activation of the caspase cascade and suppressed docetaxel-induced phosphorylation of Akt and its substrate forkhead box O1 (FOXO1). Moreover, treatment with the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 reduced the phosphorylation of FOXO1 and increased the cytotoxicity of docetaxel in A549 cells. Our findings suggest that Prx1 may modulate the chemosensitivity of lung cancer to docetaxel through suppression of FOXO1-induced apoptosis.
    International Journal of Oncology 04/2013; · 2.66 Impact Factor
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    ABSTRACT: Clostridium difficile infection (CDI) is a common nosocomial infection. Lung cancer patients have a high risk of developing CDI because of continuous antibiotic treatment or chemotherapy, prolonged hospitalization, and general weakness. This study aimed to analyze predisposing or associated risk factors for CDI in lung cancer patients receiving chemotherapy. This study was a retrospective review of 188 lung cancer patients who were admitted to the Wonkwang University Hospital between 2008 and 2009. Of the 188 patients, 44 were diagnosed with CDI. The albumin levels were significantly lower and the performance status (PS) score was significantly higher in lung cancer patients with CDI than in those without CDI (P < 0.05). In conclusion, clinicians should consider the possibility of CDI occurrence in lung cancer patients receiving chemotherapy, particularly in those with low albumin levels and high PS scores, because most lung cancer patients have a high risk of developing CDI.
    Japanese journal of infectious diseases. 01/2013; 66(5):379-82.
  • Journal of the Korean Society of Radiology. 01/2013; 68(1):27.
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    ABSTRACT: PURPOSE The main goal of this study was to evaluate which kVp is the most effective to detect the GB stones. METHOD AND MATERIALS We evaluated total 67 gallstones, which was 36 cholesterol stones from 17 patients and 31 calcium bilirubinate stones from 12 patients. Each stones were analyzed with dual energy CT (DECT) using a phantom model. Extracted stone samples were put into a distilled water-filled acrylic container phantom. DECT scans were performed using a tube voltage of 80/140 kVp and 100 /140 kVp and image sets were divided into three kVp sets, including 80, 100, 140 kVp. The Hounsfield units (HU) of each stones and bile were measured at each kVp to quantitatively compare the CT attenuation of the stones. Gallstones were divided into three categories for qualitative comparison, hyper-, iso- and hypoattenuation compared to filled water. Finally, semi-quantitative infrared spectroscopy (FTIR) was performed to confirm the chemical composition. We also reviewed HU values of GB stones on DECT images in surgically-confirmed 10 GB stones patient, 6 cases were cholesterol and 4 cases were calcium stones, in by using dual energy CT. RESULTS Stones which contain more than 80% of cholesterol on FTIR, were identified with 95.4% sensitivity on DECT of phantom. On qualitative analysis, 31stones showed hypo-, 5 showed isoattenuation at 80 kVp, and 23 stones showed hyper-, 7 showed iso- and 6 showed hypoattenuation at 140 kVp. On quantitative analysis, average CT attenuation of all cholesterol stones was calculated as -6.36 HU at 80 kVp and 28.85 HU at 140 kVp. 31 calcium stones, which contain 100% calcium bilirubinate on FTIR, were identified with 97.85% sensitivity on the phantom DECT. All calcium stones showed high attenuation at 80 kVp and 140 kVp images. 19 among 31 calcium stones showed lower HU value at 140 kVp than 80 kVp images, and the other 12 stones showed slightly higher HU value at 140kVp than 80 kVp images. By comparing with in vivo DECT, 2 among 6 cholesterol stones showed higher attenuation at 140kVp than 80 kVp images. The other 4 cholesterol stones show similar HU at 140kVp and 80kVp images. CONCLUSION DECT was useful to differentiate the cholesterol stones from calcium stones. This results may enable the identification of patients eligible for non-surgical treatment options in the future. CLINICAL RELEVANCE/APPLICATION Dual-energy CT is potentially useful for characterization of the GB stone.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE: The feasibility of using monochromatic x-ray imaging generated from an x-ray tube and a multilayer reflector for digital mammography with a low radiation dose was examined. MATERIALS AND METHODS: A multilayer mirror was designed to select the x-ray peak with an energy of 21.5 keV generated from an x-ray tube with a tungsten target and was fabricated by the ion-beam sputtering deposition system. Monochromatic x-ray images were obtained from an experimental digital mammography setup with a scanning stage. The performance of the system was evaluated using a breast phantom, a spectrometer, and a radiation dosimeter. We measured the contrast-to-noise ratio and performed the 10% modulation function test to determine image quality and resolution. RESULTS: The monochromatic beam from the multilayer reflector had a full-width-at-half-maximum of 0.9 keV at 21.5 keV, and the reflectivity was 0.70, which was 90% of the designed value. The polychromatic and monochromatic x-rays showed radiation doses of 0.497 and 0.0415 mGy, respectively. The monochromatic x-ray image shows fibers, calcifications, and masses more clearly than the polychromatic x-ray images do. The image contrast of the monochromatic x-rays was 1.85 times higher than that of the polychromatic x-rays. The experimental mammography setup had a spatial resolution of 7 lp/mm with both x-rays. CONCLUSION: Monochromatic x-rays generated using a multilayer mirror may be a useful diagnostic tool for breast examination by providing high contrast imaging with a low radiation dose.
    Investigative radiology 09/2012; · 4.85 Impact Factor
  • Kwon Su Chon, Seon Kwan Juhng, Kwon-Ha Yoon
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    ABSTRACT: An optic-based X-ray tomography system of a high spatial resolution using a conventional X-ray tube was proposed. The system had several X-ray optics: multilayer mirror for monochromatic X-ray, capillary optic for focusing X-ray onto a sample, and objective zone plate. The X-ray tomography system was designed for obtaining a spatial resolution of 100 nm. Design parameters for each optic were determined and optimized by ray tracing in considering X-ray intensity and reflectivity. The X-ray tomography system with a spatial resolution of 100 nm will provide a good inspect tool in bio-medical field and semiconductor applications.
    Current Applied Physics - CURR APPL PHYS. 01/2012;

Publication Stats

609 Citations
134.17 Total Impact Points

Institutions

  • 2006–2014
    • Wonkwang University School of Medicine and Hospital
      Riri, North Jeolla, South Korea
    • Gwangju Institute of Science and Technology
      • Department of Life Sciences
      Kwangju, Gwangju, South Korea
  • 2004–2014
    • Wonkwang University
      • • Department of Medicine
      • • Institute for Radiological Imaging Science
      Riri, North Jeolla, South Korea
  • 2013
    • Chosun University
      Gwangju, Gwangju, South Korea
  • 2009–2012
    • Catholic University of Daegu
      • Department of Radiology
      Hayang, North Gyeongsang, South Korea