• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.436-439
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• 2002

Recently, It has performed that the basic research of the photoconductive material and the development and application of the digital radiograph detector which is divided into the direct and indirect method. The objective of this study investigate the effect of the electric characteristic about changing the composition of Arsenic in hybrid detector system for compensating a defect of conventional. We fabricated samples using the amorphous Selenium and Arsenic alloy with various concentrations of the Arsenic{seven step 0.1%, 0.3%, 0.5%, 1%, 1.5%, 3%, 5%). And using EFIRON optical adhesives the formed multi-layer$(Gd_{2}O_{2}S(Eu^{2+}))$ composed phosphor layer. X-ray and light sensitivity was measured to study x-ray response characteritics. As results, highest value was measured as output net charge and SNR were $315.7pC/cm^2/mR$ and 99.4 at 0.3%As doping ratio.

• Journal of Korean Neurosurgical Society
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• v.38 no.6
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• pp.413-418
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• 2005

Objective : Although an encephaloduroarteriosynangiosis procedure using the superficial temporal artery [STA-EDAS] is an effective indirect bypass method in children with moyamoya disease[MMD], there is still a need for an additional bypass operation that can cover the area of the posterior circulation. The goal of this study is to evaluate the efficacy of the EDAS procedure using the occipital arteries [OA-EDAS]. Methods : From August 2003 to April 2004, We performed OA-EDAS in sixteen patients with MMD who have a circulatory insufficiency in the territory of the posterior cerebral artery[PCA]. The medical records were reviewed retrospectively. The surgical outcomes, including the changes in neurological status and imaging studies, with the degree of neovascularization on the cerebral angiogram, and the hemodynamic changes on single-photon emission computed tomography[SPECT], were analyzed. Results : These 16 children consisted of 5 boys and 11 girls aged 2 to 9 years. The clinical outcome of their PCA symptoms, such as visual transient ischemic attacks[TIAs] or visual field defect, was favorable in 14 patients of 16. Nine patients of 11 who underwent follow up magnetic resonance imaging[MRI] showed favorable MRI changes. On angiogram most of the patients exhibited good or fair revascularization of the PCA territory [7 of 8]. The hemodynamic changes on SPECT in the PCA territory after surgery showed improved vascular reserve in 13 of the 16 territories. Conclusion : OA-EDAS is a safe and efficacious revascularization procedure in patients with MMD who have compromised cerebral perfusion in PCA territory, or with visual TIAs.

• Archives of Craniofacial Surgery
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• v.14 no.1
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• pp.69-72
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• 2013

Lateral eyebrow mass with primary skull lesion are rare in pediatric population. Although epidermoid cyst and dermoid cyst are the most commonly encountered skull lesions in pediatric population, Langerhans cell histiocytosis (LCH) is rarely reported. We report a case of LCH arising from the lateral eyebrow with osteolytic lesion involving the frontal bone. A 5-year-old boy was presented with a hard, fixed mass in his lateral eyebrow. Contrast magnetic resonance imaging revealed inhomogeneous enhancement of the mass with direct invasion of the frontal bone and adjacent dura mater. Under general anesthesia, linear incision at the lateral eyebrow region was made. Intraoperative evaluation revealed hard, fixed and well-defined soft tissue mass. The final extirpated mass was $2.5{\times}2.4cm$ in size, and was accompanied by a $1{\times}1cm$ sized defect on the frontal bone with intact dura mater. The surgical wound was closed primarily by a layer-by-layer fashion. Histologic examination was later performed for definite diagnosis. The histologic examination revealed abnormal proliferation of Langerhans cell with granuloma formation. Radionuclide bone scan and positron emission tomography was taken and revealed free of multi-organ involvement. At 3 months after surgery, natural looking contour at the lateral eyebrow region was observed with no tumor recurrence. Differential diagnosis of the hard and fixed mass at the lateral eyebrow region affecting the primary skull lesion from pediatric population includes epidermoid cyst, dermoid cyst and LCH. Generally, brief physical examination with plain X-ray view can be performed for clinical evaluation, but for a definite diagnosis, contrast MRI may be helpful.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.25 no.2
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• pp.147-162
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• 2022

Purpose: To design a prospective study on endovascular closure of congenital portosystemic shunts. The primary endpoint was to assess the safety of endovascular closure. The secondary endpoint was to evaluate the clinical, analytical and imaging outcomes of treatment. Methods: Fifteen patients (age range: 2 days to 21 years; 10 male) were referred to our center due to congenital portosystemic shunts. The following data were collected prior to treatment: age, sex, medical history, clinical and analytical data, urine trimethylaminuria, abdominal-US, and body-CT. The following data were collected at the time of intervention: anatomical and hemodynamic characteristics of the shunts, device used, and closure success. The following data were collected at various post-intervention time points: during hospital stay (to confirm shunt closure and detect complications) and at one year after (for clinical, analytical, and imaging purposes). Results: The treatment was successful in 12 participants, migration of the device was observed in two, while acute splanchnic thrombosis was observed in one. Off-label devices were used in attempting to close the side-to-side shunts, and success was achieved using Amplatzer™ Ductus-Occluder and Amplatzer™ Muscular-Vascular-Septal-Defect-Occluder. The main changes were: increased prothrombin activity (p=0.043); decreased AST, ALT, GGT, and bilirubin (p=0.007, p=0.056, p=0.036, p=0.013); thrombocytopenia resolution (p=0.131); expansion of portal veins (p=0.005); normalization of Doppler portal flow (100%); regression of liver nodules (p=0.001); ammonia normalization (p=0.003); and disappearance of trimethylaminuria (p=0.285). Conclusion: Endovascular closure is effective. Our results support the indication of endovascular closure for side-to-side shunts and for cases of congenital absence of portal vein.

• International Journal of Stem Cells
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• v.16 no.1
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• pp.93-107
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• 2023

Background and Objectives: Chronic periodontitis can lead to alveolar bone resorption and eventually tooth loss. Stem cells from exfoliated deciduous teeth (SHED) are appropriate bone regeneration seed cells. To track the survival, migration, and differentiation of the transplanted SHED, we used super paramagnetic iron oxide particles (SPIO) Molday ION Rhodamine-B (MIRB) to label and monitor the transplanted cells while repairing periodontal bone defects. Methods and Results: We determined an appropriate dose of MIRB for labeling SHED by examining the growth and osteogenic differentiation of labeled SHED. Finally, SHED was labeled with 25 ㎍ Fe/ml MIRB before being transplanted into rats. Magnetic resonance imaging was used to track SHED survival and migration in vivo due to a low-intensity signal artifact caused by MIRB. HE and immunohistochemical analyses revealed that both MIRB-labeled and unlabeled SHED could promote periodontal bone regeneration. The colocalization of hNUC and MIRB demonstrated that SHED transplanted into rats could survive in vivo. Furthermore, some MIRB-positive cells expressed the osteoblast and osteocyte markers OCN and DMP1, respectively. Enzyme-linked immunosorbent assay revealed that SHED could secrete protein factors, such as IGF-1, OCN, ALP, IL-4, VEGF, and bFGF, which promote bone regeneration. Immunofluorescence staining revealed that the transplanted SHED was surrounded by a large number of host-derived Runx2- and Col II-positive cells that played important roles in the bone healing process. Conclusions: SHED could promote periodontal bone regeneration in rats, and the survival of SHED could be tracked in vivo by labeling them with MIRB. SHED are likely to promote bone healing through both direct differentiation and paracrine mechanisms.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.100-107
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• 2003

Purpose : To assess the usefulness of cardiac MR imaging (MRI) in the diagnosis of acute myocardial infarction and in the assessment of myocardial viability in comparision with T1-201 SPECT. Materials and Methods : We retrospectively studied 17 patients who complained of chest pain and dyspnea with cardiac MRI . The patients were evaluated for the presence or absence of high signal intensity on T2-weighted image (T2wI), abnormal wall motion on 2D-FIESTA, perfusion defect on Gd-DTPA enhanced T1WI, and delayed myocardial enhancement on 15-minutes delay Gd-DTPA enhanced T1WI. The results were correlated with the images on T1-201 SPECT, taken at rest and stress, through which reversibility of perfusion defect was assessed. Results : Both cardiac MRI and T1-201 SPECT proved to be useful methods for diagnosing acute myocardial infarction. In order of decreasing correspondence, T2WI, T1-201 SPECT, delayed enhancement study, and wall motion images all showed significant statistical correlation with the clinical diagnosis of myocardial infarction. Perfusion MRI, on the other hand, showed no significant statistical difference was found between T1-201 SPECT and cardiac MRI. The results on T2WI showed high accordance with those on Tl-201 SPECT, while delayed myocardial enhancement and wall motion studies showed no agreement with Tl-201 SPECT. Conclusion : Cardiac MRI is useful method for diagnosis of acute myocardiac infarction. With respect to the assessment of myocardial viability, the results obtained on cardiac MRI showed high agreement with those on Tl-201 SPECT. However, further study is necessary at this point for standardization and establishment of the methods for assessing myocardial viability on cardiac MRI.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.6
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• pp.519-525
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• 2009

Purpose: F-18 fluorodeoxyglucose (FDG) uptake of myocardium is influenced by various factors. Increased glycolysis, and subsequent increased F-18 FDG uptake has been reported in ischemic cardiomyopathy. However, clinical significance of incidentally found myocardial F-18 FDG uptake has not been clarified. We retrospectively reviewed the degree and pattern of myocardial uptake in patients without history of ischemic heart disease who underwent torso F-18 FDG PET/CT for evaluation of neoplastic disease. Materials and Methods: From January 2005 to June 2009, 77 patients who underwent F-18 FDG PET/CT and Tc-99m sestamibi stress/rest SPECT within 3 months were enrolled. Results: Of 77 patients, 55 (71.4%) showed increased F-18 FDG uptake in the myocardium. In this population, 40 showed uniform uptake pattern, while 15 showed focal uptake. In patients with uniform uptake, 17 showed decreased uptake in the septum without perfusion defect on myocardial SPECT. Remaining 23 patients showed uniform uptake, with 1 reversible perfusion defect and 1 fixed perfusion defect. In 15 patients with focal uptake, 9 showed increased F-18 FDG uptake in the base, and only 1 of them showed reversible perfusion defect on myocardial SPECT. In the remaining 6 focal uptake group, 4 had reversible perfusion defect in the corresponding wall, and 1 had apical hypertrophy. Conclusion: We demonstrated that septal defect pattern and basal uptake pattern in the myocardium may represent normal variants. Focal myocardial uptake other than normal variants on oncologic torso F-18 FDG PET/CT with routine fasting protocol may suggest ischemic heart disease, thus further evaluation is warranted.

• The Korean Journal of Nuclear Medicine
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• v.27 no.1
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• pp.59-64
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• 1993

To evaluate the usefulness and differences in diagnosing coronary artery disease (CAD) between men and women of intravenous dipyridamole $^{99m}Tc$-MIBI myocardial SPECT, we obtained $^{99m}Tc$-MIBI myocardial SPECT and compared with the findings of coronary angiographies. Ninety eight male and 37 female patients who underwent dipyridamole $^{99m}Tc$-MIBI myocardial imaging within one month of cardiac catheterization were studied. Scans were considered abnormal if perfusion defect was detected and the defect size was more than 12% for left anterior descending artery (LAD) and circumflex (LCX) and 8% for right coronary artery (RCA) territories. Lesions${\geqq}$50% luminal diameter narrowing were considered significant CAD. Overall sensitivity for detection of CAD was 94.3% in men and 96.4% in women; specificity was 70% in men and 52.6% in women (P=not significant, ns). Vessel-matched sensitivity was 75.3% in men and 72.7% in women (P=ns): specificity was 84.6% in men and 67.9% in women (P < 0.025). For individual coronary artery, the sensitivity in men and women was 87.7%, 81.8% for LAD; 78%, 83.3% for RCA and 52.2%, 46.7% for LCX (P=ns): the specificity was 80%, 40% for LAD (P<0.01), 82.5%, 68.4% for RCA, 88.9%, 86.4% for LCX (P=ns). The hemodynamic parameter after intravenous dipyridamole in men and women were significantly changed; the heart rate was increased and systolic, diastolic blood pressure was decreased. Adverse effects were reported in 58.8% of men and 72.7% in women (P=ns). The incidence of chest pain and headache were higher in women. There was no significant difference in the incidences of nausea, abdominal pain, dizziness, facial flushing, dyspnea. In conclusion, dipyridamole $^{99m}Tc$-MIBI myocardial SPECT is a safe, noninvasive test for evaluation of CAD. There was no gender difference to detect CAD, but more false-positive rate in women especially in the territory of LAD.

• The Korean Journal of Nuclear Medicine
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• v.26 no.2
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• pp.290-298
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• 1992

Although early diagnosis of urinary tract infection is important, the radiologic evaluation is still controversial because of the low sensitivity and the lack of cost-effectiveness. This study was carried out to evaluate the clinical utility of high resolution triple head $^{99m}Tc-DMSA$ SPECT imaging in urinary tract infection. We prospectively performed $^{99m}Tc-DMSA$ planar and SPECT imaging, ultrasound of kidney (US), intravenous pyelography (IVP) and voiding cystourethrography (VCU) in all 60 adult patients with UTI [26 with first episode of acute pyelonephritis (APN), 22 with recurrent APN, and 12 persistent asymptomatic pyuria] and 25 normal persons. To assess reversibility of the renal cortical defect (RCD), $^{99m}Tc-DMSA$ SPECT was repeated 1 to 8 months later in those patients with abnormal initial findings. Overall detection rate of $^{99m}Tc-DMSA$ SPECT imaging was 83% (50/60), but planar, US, IVP and VCU showed abnormal findings in 68%, 28%, 32% and 13%, respectively. 25 out of 27 patients with normal or single RCD were all normal in other radioligic studies. Only two patients showed vesicoureteral reflux (VUR) on VCU (grade I) and mild hydronephrosis on IVP. But, high proportion of those with multiple RCD showed abnormal findings on US (17/33), IVP (18/33), and VCU (7/33): 67% in any of these 3 studies. Especially, 3 out 7 patients with VUR showed multiple RCD on $^{99m}Tc-DMSA$ SPECT without any abnormality on IVP or US. 25 normal persons showed normal findings in all studies except one false positive finding on $^{99m}Tc-DMSA$ SPECT imaging. Follow-up $^{99m}Tc-DMSA$ SPECT was done in 28 patients (13 with single RCD, 15 with multiple RCD). All 13 patients with single RCD showed improvement. Those with multiple RCD presented improvement in 4, no change in 10, and aggravation in 1 on follow-up studies. With these results, we conclude: 1) $^{99m}Tc-DMSA$ SPECT imaging is superior to planar imaging, US, IVP or VCU in detection of renal lesion in urinary tract infection. $^{99m}Tc-DMSA$ SPECT is useful as a initial diagnostic tool in adult patients with urinary tract infection. 2) The multiple RCD on $^{99m}Tc-DMSA$ SPECT represent the high probability of irreversible tissue change and need of extensive urological work-up.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.87.1-87.1
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• 2016

The unique properties of 2D materials significantly rely on the atomic structure and defects. Thus study at atomic scale is crucial for in-depth understanding of 2D materials and provides insights into its future applications. Using aberration-corrected transmission electron microscopes, atomic resolution imaging of individual atoms has been achieved even at a low kV. Ongoing optimization of aberration correction improves the spatial resolution better than angstrom and moreover boosts the contrast of light atoms. I present the recent progress of the study on the atomic structure and defects of monolayer and multilayer graphene, hBN and MoS2. Furthermore, the defect formation mechanisms of graphene, hexagonal boron nitride and MoS2 are discussed.