• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.86-90
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• 2012

Purpose: Quantification of myocardial blood flow (MBF) using dynamic PET imaging has the potential to assess coronary artery disease. Rb-82 plays a key role in the clinical assessment of myocardial perfusion using PET. However, MBF could be overestimated due to the underestimation of left ventricular input function in the beginning of the acquisition when the scanner has non-linearity between count rate and activity concentration due to the scanner dead-time. Therefore, in this study, we evaluated the count rate linearity as a function of the activity concentration in PET data acquired in list mode. Materials & methods: A cylindrical phantom (diameter, 12 cm length, 10.5 cm) filled with 296 MBq F-18 solution and 800 mL of water was used to estimate the linearity of the Biograph 40 True Point PET/CT scanner. PET data was acquired with 10 min per frame of 1 bed duration in list mode for different activity concentration levels in 7 half-lives. The images were reconstructed by OSEM and FBP algorithms. Prompt, net true and random counts of PET data according to the activity concentration were measured. Total and background counts were measured by drawing ROI on the phantom images and linearity was measured using background correction. Results: The prompt count rates in list mode were linearly increased proportionally to the activity concentration. At a low activity concentration (<30 kBq/mL), the prompt net true and random count rates were increased with the activity concentration. At a high activity concentration (>30 kBq/mL), the increasing rate of the prompt net true rates was slightly decreased while the increasing rate of random counts was increased. There was no difference in the image intensity linearity between OSEM and FBP algorithms. Conclusion: The Biograph 40 True Point PET/CT scanner showed good linearity of count rate even at a high activity concentration (~370 kBq/mL).The result indicates that the scanner is useful for the quantitative analysis of data in heart dynamic studies using Rb-82, N-13, O-15 and F-18.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.12-16
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• 2012

Purpose : In conventional PET image reconstruction, iterative reconstruction methods such as OSEM (Ordered Subsets Expectation Maximization) have now generally replaced traditional analytic methods such as filtered back-projection. This includes improvements in components of the system model geometry, fully 3D scatter and low noise randoms estimates. SharpIR algorithm is to improve PET image contrast to noise by incorporating information about the PET detector response into the 3D iterative reconstruction algorithm. The aim of this study is evaluation of SharpIR reconstruction method in PET/CT. Materials and Methods: For the measurement of detector response for the spatial resolution, a capillary tube was filled with FDG and scanned at varying distances from the iso-center (5, 10, 15, 20 cm). To measure image quality for contrast recovery, the NEMA IEC body phantom (Data Spectrum Corporation, Hillsborough, NC) with diameters of 1, 13, 17 and 22 for simulating hot and 28 and 37 mm for simulating cold lesions. A solution of 5.4 kBq/mL of $^{18}F$-FDG in water was used as a radioactive background obtaining a lesion of background ratio of 4.0. Images were reconstructed with VUE point HD and VUE point HD using SharpIR reconstruction algorithm. For the clinical evaluation, a whole body FDG scan acquired and to demonstrate contrast recovery, ROIs were drawn on a metabolic hot spot and also on a uniform region of the liver. Images were reconstructed with function of varying iteration number (1~10). Results: The result of increases axial distance from iso-center, full width at half maximum (FWHM) is also increasing in VUE point HD reconstruction image. Even showed an increasing distances constant FWHM. VUE point HD with SharpIR than VUE point HD showed improves contrast recovery in phantom and clinical study. Conclusion: By incorporating more information about the detector system response, the SharpIR algorithm improves the accuracy of underlying model used in VUE point HD. SharpIR algorithm improve spatial resolution for a line source in air, and improves contrast recovery at equivalent noise levels in phantoms and clinical studies. Therefore, SharpIR algorithm can be applied as through a longitudinal study will be useful in clinical.

• Clinical and Experimental Pediatrics
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• v.52 no.12
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• pp.1348-1357
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• 2009

Purpose:The aims of this study were to identify the clinical characteristics and determine the changes in the expression of cytokines and apoptosis-related genes in children with infectious mononucleosis. Methods:Serological examinations of 15 pediatric patients diagnosed with infectious mononucleosis were performed prospectively. Peripheral blood from the patients was used to compare the composition of T cell subsets, cytokines, Epstein-Barr virus (EBV) DNA, and the expression of apoptosis-related genes with those in 10 healthy children. Results:Mean age of the patient group was $5.7{\pm}3.4$ (range, 3-9) years, and the male-to-female ratio was 1.5:1. Fever, sore throat, pharyngitis/tonsillitis, and cervical lymph node enlargement were the most common symptoms and signs. The proportions of CD3+ T cells, CD8+ suppressor cells, and CD56+ natural killer (NK) cells were higher in the patient group than in the control group (P<0.01). The IL-2, IL-6, and interferon $(INF)-{\gamma}$ levels were higher in the early symptomatic period (P<0.01). Mean amount of EBV DNA in the patients was $10^{2.38}copies/{\mu}g$, and the amount was the highest at the beginning of the symptomatic period and normalized during the convalescent phase. Bcl-2 expression increased during the initial phase, while Bax expression increased during the convalescent phase. Further, FasL expression increased 1 week after symptom presentation and decreased during the convalescent phase. There was no significant change in Fas expression. Conclusion:We analyzed the clinical characteristics and changes in the expression ofcytokines and apoptosis-related genes in the patients with infectious mononucleosis.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.17-23
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• 2004

Purpose : To evaluate changes in total cerebral blood flow (tCBF) with aging, parenchymal volume changes and vascular abnormalities, using 2 dimensional (D) phase-contrast magnetic resonance imaging (PC MRI). Materials and Methods : Routine brain MRI including T2 weighted image, time-of-flight (TOF) MR Angiography (MRA) and 2D PC MRI were performed in 73 individuals, including 12 volunteers. Normal subjects (12 volunteers, and 21 individuals with normal MRI and normal MRA) were classified into groups according to age (18-29, 30-49 and 50-66 years). For the group with abnormalities in brain MRIs, cerebral parenchymal volume changes were scored according to the T2 weighted images, and atherosclerotic changes were scored according to the MRA findings. Abnormal groups were classified into 4 groups: (i) mild reduction in volume, (ii) marked reduction in volume by parenchymal volume and atherosclerotic changes, and (iii) increased volume and (iv) Moya-moya disease. Volumetric flow was measured at the internal carotid artery (ICA) and vertebral artery bilaterally using the velocity-flow diagrams from PC MRI, and combined 4 vessel flows and tCBF were compared among all the groups. Results : The age-specific distribution of tCBFs in normal subjects were as follows: $12.0{\pm}2.1ml/sec$ in 18-29 years group, $11.8{\pm}1.9ml/sec$ in 30-49 years group, $10.9{\pm}2.2ml/sec$ in 50-66 years group. The distribution of tCBFs in the different subsets of the abnormal population were as follows: $9.5{\pm}2.5ml/sec$ in the group with mild reduction in volume, $7.6{\pm}2.0ml/sec$ in the group with marked reduction in volume, and $7.3{\pm}1.2ml/sec$ and $7.0{\pm}1.1ml/sec$ in the increased parenchymal volume and Moya-moya disease groups respectively. Conclusion : Total cerebral blood flow decreases with increasing age with a concomitant reduction in parenchymal volumes and increasing atherosclerotic changes. It is also reduced in the presence of increased parenchymal volume and Moya-moya disease.2D PC MRI can be used as a tool to evaluate tCBF with aging and in the presence of various conditions that can affect parenchymal volume and cerebral vasculature.

• Radiation Oncology Journal
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• v.8 no.2
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• pp.207-212
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• 1990

To determine the correlation between the response to induction chemotherapy and subsequent radiotherapy we analyzed the clinical records of 60 patients with locally advanced carcinoma of the head and neck retrospectively who had completed a full course ($2\~3$ cycle) of induction chemotherapy and curative radiotherapy in Korea Cancer Center Hospital between 1986 and 1989. Chemotherapy was administeredd with CDDP+Bleomycin (BP) in 20, CDDP+5-FU (FP) in 37, and hybrid of BP and FP in three patients. Radiotherapy was giver conventionally with a dose of 65 to 75 Gy or more over seven to eight weeks according to the size of lesion. Response rates following induction chemotherapy were $80\%$ for the tumors and $879\%$ for the nodes whereas complete reponse rates were $12\%\;and\;13\%$, respectively. Six months after radiotherapy $67\%$ of the tumors and $77\%$ of the nodes achieved a complete response. Among the 48 tumor responders and the 31 nodal responders to chemotherapy,39 ($81\%$) and 28 ($90\%$), respectively, achieved complete response after radiotherapy. Thus, whether or not the tumor and node respond to induction chemotherapy was predictive of the response to subsequent radiotherapy (p<0.0005 in tumor, p<0.0001 in node). By reanalyzing according to disease subsets (i.e. primary site, T-stage, N-stage) this relationship was not observed at T1-T2 disease (p>0.3). Therefore the tumor or node's response to induction chemotherapy is a predictor for subsequent radiotherapy except in T1-T2 tumors, and complete response to radiotherapy can be expected despite the failure of induction chemotherapy in $T_1-T_2$ tumors.

• Clinical and Experimental Pediatrics
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• v.49 no.1
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• pp.82-86
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• 2006

Purpose : The isolated microscopic hematuria is the most common abnormality detected by school urinary screening, but there is no consensus about the range of investigations and long-term outcomes of isolated hematuria in children yet. This study aims to elucidate the prognosis of hematuria and the range of diagnostic studies by follow-up results. Methods : Students with isolated hematuria who were referred to the Department of Pediatrics, Asan Medical Center from Aug. 1990 to Feb. 2004 were analysed retrospectively. Cases that presented Through significant proteinuria(>250 mg/day), other symptoms of nephritis or renal dysfunction (creatinine clearance <85 mL/min/$1.73m^2$) were excluded. Follow-up was done every six months with checking urinalysis, serum creatinine, protein and albumin. When albuminuria was detected, 24 hour urine protein was checked. Renal biopsy was done when urine protein was over 500 mg/day. Results : A total of 331 students were enrolled in this study. There were 157 males and 174 females. The mean age at presentation was $9.9{\pm}2.3$ years(7-15 years) and mean follow-up period was $2.2{\pm}1.6$ years(1-10 years). Seventy five(22.7 percent) patients showed the resolution of microscopic hematuria. The mean resolution period was $2.6{\pm}1.7$ years(1-8 years). Eight(2.4 percent) patients developed significant proteinuria and renal biopsy was done in four of them. Two cases of mild IgA nephropathy and two of minimal change were detected. None of them developed hypertension. At the end of the follow-up, renal function had remained stable in all subsets of patients. Conclusion : The prognosis of isolated microscopic hematuria was good. This study suggests that invasive studies including renal biopsy are not necessary and a regular follow-up of urinalysis is enough for children with isolated microscopic hematuria.

• Journal of Intelligence and Information Systems
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• v.18 no.4
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• pp.43-57
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• 2012

To enhance the competitive advantage in a constantly changing business environment, an enterprise management must make the right decision in many business activities based on both internal and external information. Thus, providing accurate information plays a prominent role in management's decision making. Intuitively, historical data can provide a feasible estimate through the forecasting models. Therefore, if the service department can estimate the service quantity for the next period, the service department can then effectively control the inventory of service related resources such as human, parts, and other facilities. In addition, the production department can make load map for improving its product quality. Therefore, obtaining an accurate service forecast most likely appears to be critical to manufacturing companies. Numerous investigations addressing this problem have generally employed statistical methods, such as regression or autoregressive and moving average simulation. However, these methods are only efficient for data with are seasonal or cyclical. If the data are influenced by the special characteristics of product, they are not feasible. In our research, we propose a forecasting framework that predicts service demand of manufacturing organization by combining Case-based reasoning (CBR) and leveraging an unsupervised artificial neural network based clustering analysis (i.e., Self-Organizing Maps; SOM). We believe that this is one of the first attempts at applying unsupervised artificial neural network-based machine-learning techniques in the service forecasting domain. Our proposed approach has several appealing features : (1) We applied CBR and SOM in a new forecasting domain such as service demand forecasting. (2) We proposed our combined approach between CBR and SOM in order to overcome limitations of traditional statistical forecasting methods and We have developed a service forecasting tool based on the proposed approach using an unsupervised artificial neural network and Case-based reasoning. In this research, we conducted an empirical study on a real digital TV manufacturer (i.e., Company A). In addition, we have empirically evaluated the proposed approach and tool using real sales and service related data from digital TV manufacturer. In our empirical experiments, we intend to explore the performance of our proposed service forecasting framework when compared to the performances predicted by other two service forecasting methods; one is traditional CBR based forecasting model and the other is the existing service forecasting model used by Company A. We ran each service forecasting 144 times; each time, input data were randomly sampled for each service forecasting framework. To evaluate accuracy of forecasting results, we used Mean Absolute Percentage Error (MAPE) as primary performance measure in our experiments. We conducted one-way ANOVA test with the 144 measurements of MAPE for three different service forecasting approaches. For example, the F-ratio of MAPE for three different service forecasting approaches is 67.25 and the p-value is 0.000. This means that the difference between the MAPE of the three different service forecasting approaches is significant at the level of 0.000. Since there is a significant difference among the different service forecasting approaches, we conducted Tukey's HSD post hoc test to determine exactly which means of MAPE are significantly different from which other ones. In terms of MAPE, Tukey's HSD post hoc test grouped the three different service forecasting approaches into three different subsets in the following order: our proposed approach > traditional CBR-based service forecasting approach > the existing forecasting approach used by Company A. Consequently, our empirical experiments show that our proposed approach outperformed the traditional CBR based forecasting model and the existing service forecasting model used by Company A. The rest of this paper is organized as follows. Section 2 provides some research background information such as summary of CBR and SOM. Section 3 presents a hybrid service forecasting framework based on Case-based Reasoning and Self-Organizing Maps, while the empirical evaluation results are summarized in Section 4. Conclusion and future research directions are finally discussed in Section 5.

• Biomedical Science Letters
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• v.2 no.2
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• pp.167-174
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• 1996

Alcoholics increased susceptibility to microbial infection that is associated with decreased immunity. but there has been little experimental evidence to support alcoholics-induced increase of microbial infection directly in non-specific immunity. Therefore, we were used the method of phagocytic-plaque including all the stimulating factors for the phagocytosis, subtypes of lymphocytes and T-lymphocyte proliferation. The experimental groups were divided into 3 groups: (1) alcoholics who were hospitalized less than 1 week (newly hospitalized alcoholics), (2) alcoholics who were hospitalized more than 2 weeks (old hospitalized alcoholics), (3) healthy blood donors. We have studied 98 alcoholics and 35 healthy blood donors and control groups. A physician has checked the biological markers and diagnosed the body-condition alcoholics. The immunity and non-specific immunity on the alcoholics were analyzed by using the simultest kit and flow cytometry. Proliferation of the lymphocytes was analyzed by the phytohemmagglutinine mitogen. Phagocytosis and migration properties of leukocytes were identified on the layer formed by Staphylococcus aureus Cowan I strain. Biological markers of alcoholics and control groups, by such as blood glucose, ${\gamma}$-glutamyl transpeptidase and mean corpuscular volumes of red blood cells, were determined by biochemical and hematological methods. Compared with control groups, cluster of differentiation (CD)3+, CD8+ and CD19+ in alcoholic were more decreased except CD4+/CD8+ ratio. Proliferation of the T-lymphocytes, phagocytosis and migration properties of the leukocytes in alcoholics were decreased compared with those of control groups. According to the results observed in our experiment, they can be summerized as follows: 1, Cellular, humoral and non-specific immunities, are markedly decreased in alcoholics than those in control groups. 2. It is inferred that Phagocytic plaque formation is a very useful method to evaluate phagocytosis and migration properties of the alcoholic leukocytes 3. It is thought that the subtypes of lymphocytes, especially CD4+/CD8+ ratio, are essential methods to analyzed the alcoholic immunity. 4. Specific and non-specific immunity on the old hospitalized alcoholics was slightly increased, which depends upon the alcoholic medication.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.25-29
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• 2013

Purpose: In this study, we evaluated the accuracy of CT-based attenuation correction (AC) under the conventional CT protocol (140 kVp, on average 50-60 keV) by comparing the SPECT image qualities of different energy of radioisotopes, $^{201}Tl,\;^{99m}Tc$ and $^{131}I$. Materials and Methods: Using a cylindrical phantom, three different SPECT scans of $^{201}Tl$ (70 keV, 55.5 MBq), $^{99m}Tc$ (140 keV, 281.2 MBq) and $^{131}I$ (364 keV, 96.2 MBq) were performed. The CT image was obtained with 140 kVp and 2.5 mA in GE Hawkeye 4. The OSEM reconstruction algorithm was performed with 2 iterations and 10 subsets. The experiments were performed in the 4 different conditions; non-AC and non-scatter correction (SC), only AC, only SC, AC and SC in terms of uniformity and center to peripheral ratio (CPR). Results: The uniformity was calculated from the uniform whole region in the reconstructed images. For $^{201}Tl$ and $^{99m}Tc$, the uniformities were improved by about 10-20% AC was applied, but these were decreased by about 2% as SC was applied. The uniformity of $^{131}I$ was slightly increased as both AC and SC were applied. The CPR of the reconstructed image was close to one, when AC was applied for $^{201}Tl$ and $^{99m}Tc$ scans and $^{131}I$ was distant from 1 and that is only AC. Conclusion: The image uniformity improved by AC on low energy likely to $^{201}Tl$ and $^{99m}Tc$. However, image uniformity of high energy such as $^{131}I$ was improved, when both AC and SC was applied.

• Applied Microscopy
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• v.24 no.4
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• pp.61-77
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• 1994

The calcium-binding proteins (CaBP), parvalbumin (PV) and calbindin-D 28K (calbindin) are particularly abundant and specific in their distribution, and present in different subsets of neurons in many brain regions. Although their physiological roles in the neurons have not been elucidated, they are valuable markers of neuronal subpopulations for anatomical and developmental studies. This study is designed to characterize dorsal lateral geniculate nucleus (dLGN) neurons and axon terminals in terms of differential expression of immunoreactivity (IR) for two well-known CaBPs, PV and calbindin. The experiments were carried out on 6 adult monkeys. Monkeys were perfused under deep Nembutal anesthesia with 2% paraformaldehyde and 0.2% glutaraldehyde in 0.1M phosphate buffer. After removal, the brains were postfixed for 6-8 hr in 2% paraformaldehyde at $4^{\circ}C$ and infiltrated with 30% sucrose at $4^{\circ}C$. Thereafter, they were frozen in dry ice. Serial sections of the thalamus, at $20{\mu}m$, were made in the frontal plane with a sliding microtome. The sections were stained for PV and calbindin with indirect immunocytochemical methods. For electron microscopy, after infiltration with 30% sucrose the blocks of thalamus were serially sectioned at $50{\mu}m$ with a Vibratome in the coronal plane and stained immediately by indirect ABC methods without Triton X-100 in incubation medium. Stained sections were postfixed in 0.2% osmium tetroxide, dehydrated and flat-embedded in Spurr resin. The block was then trimmed to contain only a selected lamina or interlaminar space. The dLGN proper showed strong PV IR in fibers in all laminae and interlaminar zones. Particularly dense staining was noted in layers 1 and 2 that contain many stained fibers from optic tract. Neuronal cell body stained with PV was concentrated only in the laminae. In these laminae staining was moderate in cell bodies of all large and medium-sized neurons, and was strong in cell bodies of some small neurons together with their processes. Calbindin IR was marked in the neuronal cell body and neuropil in the S layers and interlaminar zones whereas moderate in the neuropil throughout the nucleus. Regional difference in distribution of PV and calbindin IR cell is distinct; the former is only in the laminae and the latter in both the S layer and interlaminar space. The CaBP-IR elements were confined to about $10{\mu}m$ in depth of Vibratome section. The IR product for CaBP was mainly associated with synaptic vesicle, pre- and post-synaptic membrane, and outer mitochondrial membrane and along microtubule. PV-IR was noted in various neuronal elements such as neuronal soma, dendrite, RLP, F, PSD and some myelinated or unmyelinated axons, and was not seen in the RSD and glial cells. Only a few neuronal components in dLGN was IR for calbindin and its reaction product was less dense than that of PV, and scattered throughout cytoplasm of soma of some relay neurons, and was also persent in some dendrite, myelinated axons and RLP. The RSD, F, PSD and glial elements were always non-IR for calbindin. Calbindin labelled RLP were presynaptic to unlabeled dendrite or dendritic spine and PSD. Calbindin-labeled dendrite of various sizes were always postsynaptic to unlabeled RSD, RLP or F. From this study it is suggested that dLGN cells of different functional systems and their differential projection to the visual cortex can be distinguished by differential expression of PV and calbindin.