• Journal of Chest Surgery
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• v.35 no.3
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• pp.177-181
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• 2002

Background: Follow-up studies have shown that although outcomes have improved substantially over time, results of the Fontan operation and its modifications remain suboptimal. In this study, we reviewed our experience with the extracardiac conduit Fontan operation, with a focus early and midterm change of internal diameter of PTFE conduit. Material and Method: Between April 1997 and July 2000 were reviewed. Twelve patients (M:6, F:6, mean age 42.04 $\pm$ 12.43months, mean body weight 13.80$\pm$ 1.94kg) underwent extracardiac conduit Fontan operation with expanded PTFE graft. Mean cardiopulmonary bypass time was 109.7$\pm$26.99minute and mean operation time was 455$\pm$89.51minute. Intraoperative fenestration was performed in 10 patients. The aortic cross clamping was not performed in all patients. Result: There was no early deaths and no postoperative dysrhythmia. Postoperative protein losing enteropathy and prolonged pleural effusion occurred in 1(8.3%) and 4 patients(33.3%). Conduit patency was evaluated by magnetic resonance imaging studies. A 9.84$\pm$3.84% mean reduction in conduit internal diameter and there was no statistical correlation between the change of internal diameter of conduit and the postoperative duration after partial correlation analysis(r=0.019, p=0.955). Conclusion: These results demonstrate that the extracardiac conduit Fontan operation provies good early and midterm results and may reduce the prevalence of late arrhythmia. And there is no correlation between the change of internal diameter of conduit and the postoperative duration after extracardiac conduit Fontan operation with the expanded PTFE graft conduit.

• The Korean Journal of Nuclear Medicine
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• v.32 no.4
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• pp.332-343
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• 1998

Purpose: The purpose of this study was to assess the diagnostic accuracy of various quantitation methods using F-18-fluorodeoxyglucose (FDG) in patients with malignant or benign lung lesion. Materials and Methods: 22 patients (13 malignant including 5 bronchoalverolar cell cancer; 9 benign lesions including 1 hamartoma and 8 active inflammation) were studied after overnight fasting. We performed dynamic PET imaging for 56 min after injection of 370 MBq (10 mCi) of FDG. Standardized uptake values normalized to patient's body weight and plasma glucose concentration (SUVglu) were calculated. The uptake rate constant of FDG and glucose metabolic rate were quantified using Patlak graphical analysis (Kpat and MRpat), three compartment-five parameter model (K5p, MR5p), and six parameter model taking into account heterogeneity of tumor tissue (K6p, MR6p). Areas under receiver operating characteristic curves (ROC) were calculated for each method. Results: There was no significant difference of rate constant or glucose metabolic rate measured by various quantitation methods between malignant and benign lesions. The area under ROC curve were 0.73 for SUVglu, 0.66 for Kpat, 0.77 for MRpat, 0.71 for K5p, 0.73 for MR5p, 0.70 for K6p, and 0.78 for MR6p. No significant difference of area under the ROC curve between these methods was observed except the area between Kpat vs. MRpat (p<0.05). Conclusion: Quantitative methods did not improve diagnostic accuracy in comparison with nonkinetic methods. However, the clinical utility of these methods needs to be evaluated further in patients with low pretest likelihood of active inflammation or bronchoalveolar cell carcinoma.

• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.41-47
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• 1995

Tc-99m-MIBI(Sestamibi) myocardial SPECT along with T1-201 tomographic imaging has demonstrated wide application and high image qualify sufficient for the diagnosis of myocardial perfusion defect, which consequently reflects regional myocardial blood flow, The qualitative values of myocardial SPECT with Tc-99m-MIBI as well as the quantitative cases depend in some degree on the reconstruction techniques of multiple projections. Filtered backprojection(FBP) is the common standard for reconstruction rather than the complicated and time-consuming arithmetic methods. In FBP it Is known that the distribution of radioactivity in reconstructed transverse slices varies with the selected filter parameters such as cutoff frequencies and order(Butterworth case). The cutoff frequencies basically remove and decrease the true radioactive distribution and alter the pixel counts, which lead to underestimation of true counts in specific myocardial regions. In this study, we have investigated the effect of cutoff frequencies of reconstruction filter on the artifactually induced perfusion defects, which are often demonstrated near inferior and/or inferoseptal cardiac walls due to the intense hepatic uptake of Tc-99m-MIBI. A computerized method for identifying the relative degree of artifactual perfusion defect and for comparing those degrees along with the relative amount of hepatic uptake to myocardium was developed and patient images were studied to observe the quantitative degree of underestimation of myocardial perfusion, and to propose some reasonable thresh-old of cutoff frequency in the diagnosis of perfusion defect quantitatively. We concluded that from the quantitative viewpoint cutoff frequencies may be used as high as possible with the sacrifice of homogeneity of image quality, and those frequencies lower than the common 0.3 Nyquist frequency would reveal severe degradation of radio-active distribution near inferior and/or Inferoseptal myocardium when applying Butterworth or low pass filter.

• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.84-91
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• 1995

Many clinical and laboratory tests have been employed to evaluate disease activity in rheumatioid arthritis. $^{99m}Tc$-labelled polyclonal IgG(HIG) has been demonstrated to accumulate in focal sites of infection or inflammation in both animals and human subjects. The purpose of this study was to distinguish arthritis with active inflammation from those without active inflammation and to correlate relative intensities of $^{99m}Tc$-labelled HIG uptake of the rheumatoid arthritis with clinical and MR indices of the joint inflammation. This study included twelve patients with active rheumatoid arthritis, two with ankylosing spondylitis and one with degenerative osteoarthritis without active inflammation. A Whole-body and spot images were obtained 4 hours after intravenous injection of 20mCi of $^{99m}Tc$-labelled HIG. Scintigrams were assessed visually by 3 experienced radiologists, and graded as normal or mildly and markedly increased uptake within the joints, and the degree of uptake was compared with clinical and radiologic severity of synovial inflammation. MRI studies were done on the involved joints consisted of wrist(n = 11), knee(n = 2) and hip joint(n= 2). Active synovitis was defined when marked elevation of ESR and gadolinium enhancement of synovium on MRI were demonstrated. Markedly increased radiotracer uptake was seen in 10 of 11 rheumatoid arthritic patients with active synovitis whereas normal or mildly increased uptakes were noted in others, including rheumatoid arthritic patient(n=1) and non-rheumatoid patients(n = 3) without active synovitis. This study showed that the localization of involved joints in rheumatoid arthritis could be detected with $^{99m}Tc$-labelled HIG and that the degree of uptake correlated well with the degree and activity of inflammation. In conclusion, $^{99m}Tc$-labelled HIG scan is a useful method in the evaluation of active inflammation in rheumatoid arthritis.

• The Korean Journal of Nuclear Medicine
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• v.28 no.1
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• pp.62-68
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• 1994

This study was aimed to compare the density of the functional microcirculation of hepatocellular carcinoma (HCC) with normal liver and to investigate the effect of hepatic-arterial oily chemoembolization (HAE) by radionuclide examination. Methods : Eight patients with HCC proven by biopsy in five, and clinically and radiologically in three were included. The mixture of 2 cc normal saline with three to four mCi of $^{99m}Tc$-MAA was infused through a hepatic-arterial catheter for a minute. Dynamic images were obtained at a rate of 4 sec per frame for a minute, and static images and SPECT were followed. Results : In three patients who underwent hepatic arterial angiography (HAA) alone, radioactivity was markedly increased in tumors compared to the adjacent liver immediately after infusion of $^{99m}Tc$-MAA. The ratios of tumoral and extratumoral up-take (T/E ratio) were above 6.5 (range; $6.5{\sim}l9$, mean; 12.5). In four of the five patients who under-went superselective HAE, T/E ratio were remark-ably decreased ($0.5{\sim}1.3$). The areas of embolization were better delineated in radionuclide study than in postembolization HAA. In the other one who was considered to be embolized completely on HAA, strong radiouptake in the tumor was disclosed (T/E ratio; 7.0). Conclusions : Therefore hepatic-arterial flow study with radionuclide imaging using $^{99m}Tc$-MAA can be a valuable method to assess the accurate embolization effect in HCC.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.293-300
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• 1994

It is well known that Tc-99m HMPAO brain SPECT can reflect the functional lesions better than X-ray computerized tomography(CT) and magnetic resonance imaging(MRI) in the cerebral disorders. In order to evaluate the clinical utilities of Tc-99m HMPAO brain SPECT in patients with post-traumatic chronic organic mental disorder(OMD), we included 28 patients diagnosed as OMD in department of psychiatry after traumatic head injury. And we compared the results of Tc-99m HMPAO SPECT with those of MRI, EEG and MINI mental status ex amination(MMSE). The results were as follows 1) All patients diagnosed as OMD showed diffuse or focal decreased cerebral perfusion on Tc-99m HMPAO SPECT. 2) Most frequent lesion on brain Tc-99m HMPAO SPECT was decreased perfusion on both frontal lobe. And most frequent lesion on brain Tc-99m HMPAO SPECT showing normal brain MRI result was also decreased both frontal perfusion. 3) Eight of 28 patients showed focal brain MRI lesions(4 small frontal hygroma, 3 small cerebral infarction and 1 cerebellar encephalomalacia) which were not detected in brain Tc-99m HMPAO SPECT. 4) The patients showing less than 20 points on MMSE disclosed abnormal results of EEG more frequently than those disclosing more than 20 points. In conclusion, we think that Tc-99m HMPAO brain SPECT is sensitive method to detect functional lesions of the brains in patients with chronic post-traumatic organic mental disorder.

• Geophysics and Geophysical Exploration
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• v.9 no.4
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• pp.279-290
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• 2006

The borehole radar methods used to tunnel detection are mainly classified into borehole radar reflection, directional antenna, crosshole scanning, and radar tomography methods. In this study, we have investigated the feasibility and limitation of each method to tunnel detection through case studies. In the borehole radar reflection data, there were much more clear diffraction signals of the upper wings than lower wings of the hyperbolas reflected from the tunnel, and their upper and lower wings were spreaded out to more than 10m higher and lower traces from the peaks of the hyperbolas. As the ratio of borehole diameter to antenna length increases, the ringing gets stronger on the data due to the increase in the impedance mismatching between antennas and water in the boreholes. It is also found that the reflection signals from the tunnel could be enhanced using the optimal offset distance between transmitter and receiver antennas. Nevertheless, the borehole radar reflection data could not provide directional information of the reflectors in the subsurface. Direction finding antenna system had a advantage to take a three dimensional location of a tunnel with only one borehole survey even though the cost is still very high and it required very high expertise. The data from crosshole scanning could be a good indicator for tunnel detection and it could give more reliable result when the borehole radar reflection survey is carried out together. The images of the subsurface also can be reconstructed using travel time tomography which could provide the physical property of the medium and would be effective for imaging the underground structure such as tunnels. Based on the results described above, we suggest a cost-effective field procedure for detection of a tunnel using borehole radar techniques; borehole radar reflection survey using dipole antenna can firstly be applied to pick up anomalous regions within the borehole, and crosshole scanning or reflection survey using directional antenna can then be applied only to the anomalous regions to detect the tunnel.

• Journal of Radiation Protection and Research
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• v.40 no.2
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• pp.79-86
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• 2015

$^3He$ gas has been used for neutron monitors as the neutron converter owing to its advantages such as high sensitivity, good ${\gamma}$-discrimination capability, and long-term stability. However, $^3He$ is becoming more difficult to obtain in last few years due to a global shortage of $^3He$ gas. Accordingly, the cost of a neutron monitor using $^3He$ gas as a neutron converter is becoming more expensive. Demand on a neutron monitor using an alternative neutron conversion material is widely increased. $^{10}B$ has many advantages among various $^3He$ alternative materials, as a neutron converter. In order to develop a neutron converter using $^{10}B$ (actually $B_4C$), we calculated the optimal thickness of a neutron converter with a Monte Carlo simulation using MCNP6. In addition, a neutron converter was fabricated by the Ar sputtering method and the neutron signal detection efficiencies were measured with respect to various thicknesses of fabricated a neutron converter. Also, we developed a 2-dimensional multi-wire proportional chamber (MWPC) for neutron beam profile monitoring using the fabricated a neutron converter, and performed experiments for neutron response of the neutron monitor at the 30 MW research reactor HANARO at the Korea Atomic Energy Research Institute. The 2-dimensional MWPC with boron ($B_4C$) neutron converter was proved to be useful for neutron beam monitoring, and can be applied to other types of neutron imaging.

• Tuberculosis and Respiratory Diseases
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• v.45 no.4
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• pp.760-765
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• 1998

Background: Glucose uptake has been found to be increased in cancer cells, and FDG-PET imaging is used for diagnosis of cancer using this phenomenon. However, the exact mechanism of increased glucose uptake in cancer cells has not been clarified. Recent studies demonstrated the presence of glucose transporter(GLUT) mRNA expression in gastrointestinal cancer and head and neck cancer, and suggested that GLUT may be associated with glucose uptake in cancer cells. In lung cancer cells, glucose metabolism is also known to be increased. We evaluated GLUT mRNA expression in human lung cancer cell lines in order to find out the mechanism of increased glucose uptake in lung cancer. Method: Total RNA was isolated from 15 human lung cancer cell lines and immortalized bronchial epithelial cell line(BEAS-2B). After electrophoresis of $20{\mu}g$ total RNA, Northern blot analysis was done using GLUT1 cDNA and GLUT3 cDNA as probes. Results: Thirteen of 14 human lung cancer cell lines expressed GLUT1 mRNA and 10 of 14 human lung cancer cell lines expressed GLUT3 mRNA. Eight human lung cancer cell lines expressed both GLUT mRNAs. BEAS-2B expressed GLUT1 mRNA and did not express detectable GLUT3 mRNA. Conclusion: The increase of glucose metabolism in lung cancer may be associated with GLUT1 and GLUT3 expression.

• Progress in Medical Physics
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• v.23 no.4
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• pp.252-260
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• 2012

The reduction of radiation dose from x-ray is a main concern in computed tomography (CT) imaging due to the side-effect of the dose on human body. Recently, the various methods for dose reduction have been studied in CT and one of the method is a iterative reconstruction based on total variation (TV) minimization at few-views data. In this paper, we evaluated the image quality between total variation (TV) minimization algorithm and Feldkam-Davis-kress (FDK) algorithm in micro computed tomography (CT). To evaluate the effect of TV minimization algorithm, we produced a cylindrical phantom including contrast media, water, air inserts. We can acquire maximum 400 projection views per rotation of the x-ray tube and detector. 20, 50, 90, 180 projection data were chosen for evaluating the level of image restoration by TV minimization. The phantom and mouse image reconstructed with FDK algorithm at 400 projection data used as a reference image for comparing with TV minimization and FDK algorithm at few-views. Contrast-to-noise ratio (CNR), Universal quality index (UQI) were used as a image evaluation metric. When projection data are not insufficient, our results show that the image quality of reconstructed with TV minimization is similar to reconstructed image with FDK at 400 view. In the cylindrical phantom study, the CNR of TV image was 5.86, FDK image was 5.65 and FDK-reference was 5.98 at 90-views. The CNR of TV image 0.21 higher than FDK image CNR at 90-views. UQI of TV image was 0.99 and FDK image was 0.81 at 90-views. where, the number of projection is 90, the UQI of TV image 0.18 higher than FDK image at 90-views. In the mouse study UQI of TV image was 0.91, FDK was 0.83 at 90-views. the UQI of TV image 0.08 higher than FDK image at 90-views. In cylindrical phantom image and mouse image study, TV minimization algorithm shows the best performance in artifact reduction and preserving edges at few view data. Therefore, TV minimization can potentially be expected to reduce patient dose in clinics.