• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.169-172
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• 1996

In this paper, we present the evaluation of signal to noise ratio(SNR) and images of Magnetic resonance imaging system which is underdevelopement. For the evaluation of such parameters, we used two different phantoms, one for SNR and image homogeneity, and the other is for the slice thickness measurement. Further, comparison with other leading MR systems may be needed for the better image quality assessment.

• Neonatal Medicine
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• v.17 no.1
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• pp.64-74
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• 2010

Purpose : The aim of this study was to determine the risk factors, clinical characteristics and prognosis for the development of periventricular leukomalacia (PVL) in preterm infants according to the extent and site of the PVL. Methods : The medical records of infants (under 36 weeks of gestational age) delivered from January 1999 to December 2008 were reviewed. Twenty-five preterm infants with were PVL were diagnosed by brain magnetic resonance imaging (MRI) and an addition 50preterm infants with no brain lesions were enrolled in this study. The perinatal and neonatal risk factors for the development of PVL was determine in these infants. Mental and Psychomotor Developmental Indices (MDI, PDI) were assessed by a clinical psychologist using the Bayley Scales of Infant Development II. We compared the differences of the clinical characteristics and prognosis according to brain MRI findings. Results : Maternal fever, young maternal age, extended oxygen use, hypotension within the first week of birth, use of inotropics within the first week of birth, and respiratory distress syndrome were the risk factors associated with PVL (P <0.05). In the multivariate analysis, maternal fever and extended oxygen use were statistically significant independent risk factors (P <0.05). The mean MDI and PDI scores of the PVL group (74.4$\pm$ 27.8 and 58.0$\pm$17.7) were significantly lower than those of the control group (103.5$\pm$8.9 and 101.7$\pm$16.1, P <0.05). Conclusion : Maternal fever and extended oxygen use were independent risk factors for PVL. We should pay attention to infants who had the risk factors and follow them up closely by brain imaging study and Bayley Scales of Infant Development II.

• Investigative Magnetic Resonance Imaging
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• v.13 no.1
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• pp.81-87
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• 2009

Purpose : We sought to evaluate enhancement of plaque with gadolinium-based contrast agent by magnetic resonance imaging (MRI) in comparison with histopathology, namely lipid-rich and macrophage-rich components that were two representative characteristics of plaque vulnerability using atherosclerotic rabbit aorta in order to determine which histopathologic component is relevant to the enhancement. Materials and Methods : New Zealand white rabbit (n=4, weight 3.0 to 3.5 kg, all male) was used for animal model of atherosclerosis. Atherosclerotic aortic lesions were induced by high-cholesterol diet and double balloon injury. T1-weight axial images were acquired before and after gadolinium-based contrast agent using a 3-T MRI. MR images and the matched histopathological sections (n=35) were divided into 4 quadrants or 3 (n=130). Enhancement ratio (ER, ER=SIpost/SIpre) on MRI was calculated for each quadrant and compared with histopathology in regard to lipid-rich and macrophage-rich areas. Results : Lipid-rich quadrants were 72 and fibrous quadrants were 58. The number of quadrants which had macrophage-rich areas was 105 and that of quadrants which did not have macrophage-rich areas was 25. ER was significantly higher in lipid-rich quadrants than in fibrous quadrants (mean ER 2.25c$\pm$0.41 vs. 2.72$\pm$0.65, p=0.013). ER poorly correlated with macrophage-rich areas when lipid-component was controlled (correlation coefficient -0.203, p=0.236). Conclusion : Lipid-rich plaques showed stronger enhancement than fibrous plaques using a standard gadolinium-based extracellular contrast agent. Macrophage infiltration did not correlate with degree of enhancement. Further study is warranted that account for optimal time of imaging after contrast injection using various plaque models from early to advanced stages and all possible parameters associated with contrast enhancement.

• Investigative Magnetic Resonance Imaging
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• v.17 no.1
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• pp.1-7
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• 2013

Purpose : The purpose of this study is to correlate the imaging findings and the clinical findings in patients with transient splenial lesions (TSL). Materials and Methods: Total of 7 patients (M: F = 4: 3; age range 11 - 38 years, mean age 25.5 years) were studied between November 2006 and April 2011. The MRI findings and clinical findings in all patients were retrospectively reviewed. The location, MR signal intensity, restricted diffusion, enhancement pattern and reversibility from the follow up images were reviewed. Clinical features were reviewed with respect to the presented symptoms, signs, treatment and outcome. Results: The lesions were located in the splenium of corpus callosum in all patients. All lesions showed high signal intensity on diffusion weighted imaging (DWI), and six patients showed restricted diffusion on the apparent diffusion coefficient (ADC) map. ADC map was not available in one patient. All lesions (n = 7) showed high signal intensity on the T2 weighted image (T2WI). Five of the patients (71.4%) with follow up images (range 7 - 34 days) showed complete resolution of focal high signal intensity on DWI, with recovery of ADC values as well as T2WI. After contrast media administration, none of the lesions showed any enhancements. All lesions with various etiologies including TB medication were developed in younger age patients and showed reversibility after the acceptable period of minimum 7 days with conservative treatment. Conclusion: All TSL showed nonspecific imaging findings, including restricted diffusion on DWI and ADC map on the initial images. However, reversibility of the lesions and the young age preference can be a characteristic finding of TSL with acceptable period of minimum 7 days. In addition, to keep it in mind that various etiologies including TB medication may cause TSL, is important for radiologists as well as clinicians.

• Korean Journal of Biological Psychiatry
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• v.19 no.3
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• pp.121-127
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• 2012

Objectives : The multimodal telepresence systems have been adopted in a variety of applications, such as telemedicine, space or underwater teleoperation and videoconference. Multimedia, one of the telepresence systems, has been used in various fields including entertainment, education and communication. The degree of subjective telepresence is defined as the probability that a person perceives to be physically in the remote place when he/she experiences a multisensory feedback from the multimedia. The current study aimed to explore the neural mechanism of telepresence related to multisensory feedback in patients with schizophrenia. Methods : Brain activity was measured using functional magnetic resonance imaging while fifteen healthy controls and fifteen patients with schizophrenia were experiencing filmed referential conversation at various distances (1 m, 5 m and 10 m). Correlations between the image contrast values and the telepresence scores were analyzed. Results : Subjective telepresence was not significantly different between the two groups. Some significant correlations of brain activities with the telepresence scores were found in the left postcentral gyrus, bilateral inferior frontal gyri, right fusiform gyrus, and left superior temporal sulcus. There were no main effects of group and distance. Conclusion : These results suggest that patients with schizophrenia experience telepresence as appropriately as healthy people do when exposed to multimedia. Therefore, patients with schizophrenia would have no difficulty in immersing themselves in multimedia which may be used in clinical training therapies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1124-1131
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• 2011

In this paper, image reconstruction algorithm for breast cancer detection using MT(Microwave Tomography) was investigated. The breast cancer detection system under development uses 16 transmit/receive antennas. The signal waveform was a sinusoidal wave at 900 MHz. To solve the 2D inverse scattering problem, we used the 2D FDTD (Finite Difference Time Domain) method for forward calculation and LMA(Levenberg-Marquardt Algorithm) for optimization. The result of the image reconstruction using the numerical phantom by MRI(Magnetic Resonance Imaging) obtained from real patient of breast cancer showed that we can detect the position of the tumor accurately.

• The Journal of the Korean bone and joint tumor society
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• v.5 no.1
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• pp.44-50
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• 1999

Neurilemmoma is a benign encapsulated nerve sheath tumor originated from peripheral nerve. Previously its preoperative diagnosis had mainly depended on the history, physical examination, electrodiagnostic test, ultrasonography, bone scan. But only with these diagnostic modalities, exact preoperative diagnosis was nearly impossible. Therefore operation was performed under the impression of lipoma or just simple soft tissue tumor. Recently, the advent of magnetic resonance imaging(MRI) has made it easier to diagnose neurilemoma before surgery. MRI also helps to determine the extent of lesion and operative procedures. We performed marginal excision in 24 cases, evaluated those cases with respect to the sex, age, location, chief complaint, duration of illness, preoperative diagnosis, involved nerve, imaging studies, size of mass, complication, duration of follow-up and report with review of the literature.

• Progress in Medical Physics
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• v.21 no.1
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• pp.42-51
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• 2010

Imaging studies using MRI, PET, and/or MEG have been primary evaluation methods to quantitatively assess cognitive function. Recent advances in computational technology and information technology may allow a novel evaluation methodology to quantitate cognitive function more cost-effectively. In this study, we developed a software package composed of a series of tests to evaluate cognitive ability combined with a user-friendly touch screen input device. This cognitive assessment tool can quantitate concentration, numeric memory, associative memory, topological memory, visual and muscular reaction, and acoustic reaction over a relatively short testing time. We performed an empirical study on eighty normal subjects aged 20 and 59 years old using the developed evaluation methods. Age-related cognitive deterioration after 40 years old was confirmed. There was no difference in cognitive ability between male and female in the same age group. This study demonstrates the feasibility of a simple but effective evaluation software tool to quantitatively assess cognitive ability. This methodology may provide improved accessibility and reduced costs to perform cognitive function studies to compare between various subject groups.

• Investigative Magnetic Resonance Imaging
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• v.15 no.2
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• pp.165-169
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• 2011

Cardiac myxoma is the most common benign tumor of the heart. However, low incidence of recurrence and metastasis has been reported. A 49-year-old female patient was admitted in the hospital due to sudden onset of left side weakness. Magnetic resonance imaging (MRI) of brain showed multifocal areas of diffusion restriction on diffusion weighted images. Echocardiography was performed to evaluate the cause of embolic brain infarction and cardiac myxoma was found in the left atrium. The patient underwent complete excision of the mass. One year later, the patient was readmitted with symptoms of dysarthria. Brain MRI showed newly developed multiple hemorrhagic metastatic lesions. The patient underwent radiotherapy of the metastatic lesions. Although rare, cardiac myxoma can cause delayed metastasis. We report a rare case of delayed multiple cerebral metastases from the completely resected cardiac myxoma.

• Korean Journal of Cognitive Science
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• v.18 no.2
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• pp.139-157
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• 2007

We compared brain activation areas during participants drawn from contrasting two college majors performed intentionality detection (known as the basic mechanism of theory of mind) task using fMRI. The main purpose of this study was to identify whether individual differences are present in intentionality detection or not. In psychology major, the left inferior frontal gyrus, the fusiform gyrus, the superior temporal gyrus and the right fusiform gyrus, the supramarginal gyrus were activated. In engineering major, the inferior parietal lobule and the superior parietal lobule were found. This result suggests that according to participants' major, different brain areas were activated. The relations between performance of the intentionality detection task and the individual variants of participants were discussed.