• Korean Journal of Radiology
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• v.23 no.8
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• pp.777-784
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• 2022

• Imaging Science in Dentistry
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• v.45 no.1
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• pp.49-54
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• 2015

Odontomas are nonaggressive, hamartomatous developmental malformations composed of mature tooth substances and may be compound or complex depending on the extent of morphodifferentiation or on their resemblance to normal teeth. Among them, complex odontomas are relatively rare tumors. They are usually asymptomatic in nature. Occasionally, these tumors become large, causing bone expansion followed by facial asymmetry. Odontoma eruptions are uncommon, and thus far, very few cases of erupted complex odontomas have been reported in the literature. Here, we report the case of an unusually large, painless, complex odontoma located in the right posterior mandible.

• Imaging Science in Dentistry
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• v.45 no.3
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• pp.193-198
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• 2015

Noma is a gangrenous disease of the orofacial region that leads to severe facial tissue destruction and is a significant cause of death among children. With the advent of modern antibiotics and improved nutrition, children with noma may survive into adulthood, but must face the challenge of undergoing repair of the sequelae of noma. This report describes a case of bony fusion of the maxilla and mandible in a 28-year-old female patient, which was a sequelae of a childhood case of noma.

• The Journal of the Korean bone and joint tumor society
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• v.11 no.1
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• pp.32-39
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• 2005

Introduction: Currently, F-18 fluorodeoxyglucose positron emission tomography scans (FDG-PET) has been investigated in soft tissue tumor especially for tumor detection and noninvasive grading. However, the validity and the efficacy of FDG-PET are still unclear in clinical evaluation. The purpose of this study is to determine the efficacy of FDG-PET in compared to conventional diagnostic imaging studies currently used in the soft tissue tumor. Methods: Between March 2001 and March 2002, 29 patients (sixteen males, thirteen females, mean age, 47 years; a range from 4 to 73) diagnosed with soft tissue tumor were evaluated by both conventional diagnostic imaging and FDG-PET. Valid reference test of the local lesion was the histopathologic diagnosis, which was measured in all patients. The suspecting metastasis in the imaging studies was validated by pathology or follow up imaging for at least 6 months. Each imaging diagnosis was made independently. The accuracy of each diagnostic method was evaluated. The incremental cost accuracy ratio was determined in each diagnostic method. Results: For detection of local lesion, sensitivity, specificity, and accuracy for MRI and FDGPET scans were 91%, 57%, 83% and 95%, 43%, 83% respectively. For detection of distant lesion, sensitivity, specificity, accuracy for conventional diagnostic methods and FDG-PET scans were 77%, 89%, 87% and 92%, 94%, 93% respectively. The incremental cost accuracy ratio (ICAR) of FDG-PET for detection of distant lesion was 145,000won/%. According to ICAR for each tumor grade, PET strategy is most cost-effective at high grade tumors. Conclusions: For detection of local lesion such as recurrence or remnant tumor, FDG-PET scan was not more accurate than MRI. However, It was more accurate for detection of metastatic lesion than conventional methods. For detection of high grade tumor, PET was most costeffective than for detection of lower grade tumor.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.107-113
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• 1999

The purpose of this study was to develop a miniature imaging gamma probe with high performance that can detect small or residual tumors after surgery. Gamma probe detector system consists of NaI(Tl) scintillator, position sensitive photomultiplier tube (PSPMT), and collimator. PSPMT was optically coupled with 6.5 mm thick, 7.62 cm diameter of NaI(Tl) crystal and supplied with -1000V for high voltage. Parallel hexagonal hole collimator was manufactured for characteristics of 40-mm hole length, 1.3-mm hole diameter, and 0.22 mm septal thickness. Electronics consist of position and trigger signal readout systems. Position signals were obtained with summing, subtracting, and dividing circuit using preamplifer and amplifier. Trigger signals were obtained using summing amplifier, constant fraction discriminator, and gate and delay generator module with preamplifer. Data acquisition and processing were performed by Gamma-PF interface board inserted into pentium PC and PIP software. For imaging studies, flood and slit mask images were acquired using a point source. Two hole phantom images were also acquired with collimator. Intrinsic and system spatial resolutions were measured as 3.97 mm and 5.97 mm, respectively. In conclusion, Miniature gamma probe images based on the PSPMT showed good image quality, we conclude that the miniature imaging gamma probe was successfully developed and good image data were obtained. However, further studies will be required to optimize imaging characteristics.

• Journal of the Korean Society of Radiology
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• v.83 no.5
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• pp.1014-1031
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• 2022

The Kasai portoenterostomy is the first-line treatment for the restoration of the flow of bile to the small intestine in patients with biliary atresia. Various complications can occur after Kasai portoenterostomy, including ascending cholangitis, biliary cirrhosis, and portal hypertension. Of these potential complications, ascending cholangitis in the most common. In cases of patients having uncontrolled complications due to progressive liver cirrhosis, portal hypertension, or progressive hyperbilirubinemia, liver transplantation is the indicated as treatment plan. Lifelong follow-up, particularly involving imaging studies, is important for the identification of various complications arising from biliary atresia after Kasai portoenterostomy. Additionally, imaging studies play a crucial role in the evaluation of potential liver donors and recipients. US is a key imaging modality utilized in the management of patients who undergo Kasai portoenterostomy, while CT and MRI are imperative to obtaining an accurate diagnosis.

• Molecules and Cells
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• v.26 no.2
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• pp.113-120
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• 2008

Laser light microscopy enables observation of various simultaneously occurring events in living cells. This capability is important for monitoring the spatiotemporal patterns of the molecular interactions underlying such events. Two-photon excited fluorescence microscopy (two-photon microscopy), a technology based on multiphoton excitation, is one of the most promising candidates for such imaging. The advantages of two-photon microscopy have spurred wider adoption of the method, especially in neurological studies. Multicolor excitation capability, one advantage of two-photon microscopy, has enabled the quantification of spatiotemporal patterns of $[Ca^{2+}]_i$ and single episodes of fusion pore openings during exocytosis. In pancreatic acinar cells, we have successfully demonstrated the existence of "sequential compound exocytosis" for the first time, a process which has subsequently been identified in a wide variety of secretory cells including exocrine, endocrine and blood cells. Our newly developed method, the two-photon extracellular polar-tracer imaging-based quantification (TEPIQ) method, can be used for determining fusion pores and the diameters of vesicles smaller than the diffraction-limited resolution. Furthermore, two-photon microscopy has the demonstrated capability of obtaining cross-sectional images from deep layers within nearly intact tissue samples over long observation times with excellent spatial resolution. Recently, we have successfully observed a neuron located deeper than 0.9 mm from the brain cortex surface in an anesthetized mouse. This microscopy also enables the monitoring of long-term changes in neural or glial cells in a living mouse. This minireview describes both the current and anticipated capabilities of two-photon microscopy, based on a discussion of previous publications and recently obtained data.

• Journal of Biomedical Engineering Research
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• v.29 no.6
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• pp.436-442
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• 2008

Magnetic resonance electrical impedance tomography(MREIT) has been suggested to produce cross-sectional conductivity images of an electrically conducting object such as the human body. In most previous studies, recessed electrodes have been used to inject imaging currents into the object. An MRI scanner was used to capture induced magnetic flux density data inside the object and a conductivity image reconstruction algorithm was applied to the data. This paper reports the performance of a thin and flexible carbon-hydrogel electrode that replaces the bulky and rigid recessed electrode in previous studies. The new carbon-hydrogel electrode produces a negligible amount of artifacts in MR and conductivity images and significantly simplifies the experimental procedure. We can fabricate the electrode in different shapes and sizes. Adding a layer of conductive adhesive, we can easily attach the electrode on an irregular surface with an excellent contact. Using a pair of carbon-hydrogel electrodes with a large contact area, we may inject an imaging current with increased amplitude primarily due to a reduced average current density underneath the electrodes. Before we apply the new electrode to a human subject, we evaluated its performance by conducting MREIT imaging experiments of five swine legs. Reconstructed conductivity images of the swine legs show a good contrast among different muscles and bones. We suggest a future study of human experiments using the carbon-hydrogel electrode following the guideline proposed in this paper.

• Clinical and Experimental Pediatrics
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• v.58 no.2
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• pp.69-72
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• 2015

Insulinoma, which arises from insulin-producing pancreatic beta cells, is a rare tumor in children. Only 5%-10% of insulinomas are malignant and undergo metastasis. We report a case of an 11-year-old girl who experienced hypoglycemia-related seizures induced by an insulinoma; after resection of the primary tumor, she developed hepatic focal nodular hyperplasia (FNH). Laboratory test results indicated marked hypoglycemia with hyperinsulinemia. Abdominal ultrasonography (US) and computed tomography results were normal; however, magnetic resonance imaging (MRI) showed a solid mass in the pancreatic tail. Therefore, laparoscopic distal pancreatectomy was performed. Two months after the surgery, an abdominal MRI revealed multiple nodular lesions in the liver. An US-guided liver biopsy was then performed, and histological examination revealed FNH without necrosis or mitotic activity. The patient has been free of hypoglycemia for 2 years, and recent MRI studies showed a decrease in the size of FNH lesions, without any evidence of metastasis. Even though no metastatic lesions are noted on imaging, close observation and follow-up imaging studies are required in a child with insulinoma that has malignant potential on histopathologic findings.

• Korean Journal of Biological Psychiatry
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• v.15 no.2
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• pp.110-117
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• 2008

Objectives : Posttraumatic stress disorder(PTSD) has been primarily associated with emotional problems. Recently, however, the impact of PTSD on cognitive processes has interested a growing number of researchers. The current study is aimed at investigating the cognitive aspects of PTSD at both behavioral and neurological levels. Methods : We recruited individuals with PTSD who survived the Daegu subway explosion in 2003 as well as non-PTSD individuals as a control group. To evaluate the inhibitory processes and the neural mechanisms, we had these individuals perform the negative priming task simultaneously with functional MRI scanning. Results : Behaviorally, the negative priming effect was intact in the control group but was not evident in the PTSD group. In the imaging results, only the PTSD group showed the negative priming effect (i.e., increased activation of the negative priming condition as opposed to the neutral condition) in the dorsolateral prefrontal cortex, anterior cingulate cortex, and inferior temporal gyrus. The PTSD group also showed increased activity for the positive priming condition as opposed to the neutral condition in the claustrum. These results confirm and extend the previous findings that the integrity of the ACC is compromised in the trauma survivors due to disrupted white matter tract. Conclusions : The current results suggest that deteriorated performance of the PTSD group may be due to the functional problem as well as the structural abnormalities.