• Communications of the Korean Mathematical Society
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• v.16 no.3
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• pp.519-541
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• 2001

Magnetic Resonance Electrical Impedance Tomography(MREIT) is a new medical imaging technique for the cross-sectional conductivity distribution of a human body using both EIT(Electrical Impedance Tomography) and MRI(Magnetic Resonance Imaging) system. MREIT system was designed to enhance EIT imaging system which has inherent low sensitivity of boundary measurements to any changes of internal tissue conductivity values. MREIT utilizes a recent CDI (Current Density Imaging) technique of measuring the internal current density by means of MRI technique. In this paper, a mathematical modeling for MREIT and image reconstruction method called the alternating J-substitution algorithm are presented. Computer simulations show that the alternating J-substitution algorithm provides accurate high-resolution conductivity images.

• Investigative Magnetic Resonance Imaging
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• v.20 no.2
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• pp.123-126
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• 2016

The flexor digitorum accessorius longus (FDAL) is the most common accessory muscle found in the posterior compartment of the ankle area. The accessory muscle in this area such as the FDAL may be incidentally identified on magnetic resonance images (MRI). There are some case reports about the FDAL in cadaver researches. However, the MRI findings about the FDAL have been reported in a few cases. In this paper, we report a case of the FDAL incidentally identified on MRI with review of the literature about the FDAL.

• Imaging Science in Dentistry
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• v.53 no.2
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• pp.161-168
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• 2023

Nasopalatine duct cysts (NPDCs), the most common non-odontogenic cysts of maxilla, are often incidental findings on diagnostic imaging. When symptomatic, they usually present as a painless swelling with possible fistula. Conventional radiography shows a round-to-ovoid or heart-shaped radiolucency between the roots of central maxillary incisors. While the radiographic features of NPDCs in X-ray-based modalities have been well described, their magnetic resonance imaging (MRI) features have rarely been reported. Developments in dental MRI in recent years and the introduction of various dental MRI protocols now allow a wide range of applications in dental medicine. MRI is becoming an important tool for the detection and diagnosis of incidental or non-incidental dentomaxillofacial cysts. This report presented and discussed the characteristics of 2 NPDC cases visualized on MRI using both conventional and newly implemented specific dental MRI protocols with a novel 15-channel mandibular coil, demonstrating the use of these protocols for radiation-free maxillofacial diagnoses.

• Investigative Magnetic Resonance Imaging
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• v.24 no.3
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• pp.154-161
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• 2020

Purpose: A CT angiography spot sign (CTA-spot) is a significant predictor of the early expansion of an intracerebral hemorrhage (ICH-Ex). Dynamic-susceptibility-contrast magnetic resonance imaging (DSC-MRI) can track the real-time leaking of contrast agents. It may be able to indicate active bleeding, like a CTA-spot. Materials and Methods: From September 2014 to February 2017, we did non-contrast CT, CTA, and DSC-MRI examinations of seven patients with acute ICH. We investigated the time from symptom onset to the first contrast-enhanced imaging. We evaluated the time course of the contrast leak within the ICH at the source image of the DSC-MRI and the volume change of ICH between non-contrast CT and DSC-MRI. We compared the number of slices showing CTA-spots and DSC-MRI leaks. Results: The CTA-spot and DSC-MRI leak-sign were present in four patients, and two patients among those showed ICH-Ex. The time from the symptom onset to CTA or DSC-MRI was shorter for those with a DSC-MRI leak or CTA-spot than for three patients without either (70-130 minutes vs. 135-270 minutes). The leak-sign began earlier, lasted longer, and spread to more slices in the patients with ICH-Ex than in those without ICH-Ex. The number of slices of the DSC-MRI leak and the number of the CTA-spot were well correlated. Conclusion: DSC-MRI can demonstrate the leakage of GBCA within hyperacute ICH, showing the good contrast between hematoma and contrast. The DSC-MRI leakage sign could be related to the hematoma expansion in patients with ICH.

• Investigative Magnetic Resonance Imaging
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• v.25 no.2
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• pp.101-108
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• 2021

Purpose: To identify characteristic magnetic resonance imaging (MRI) features to differentiate between Krabbe disease and metachromatic leukodystrophy (MLD) in young children. Materials and Methods: We collected all confirmed cases of Krabbe disease and MLD between October 2004 and September 2020 at Seoul National University Children's Hospital. Patients with initial MRI available were included. Their initial MRIs were retrospectively reviewed for the following: 1) presence of white matter signal abnormality involving the periventricular and deep white matter, subcortical white matter, internal capsule, brainstem, and cerebellum; 2) presence of volume decrease and signal alteration in the corpus callosum and thalamus; 3) presence of the tigroid sign; 4) presence of optic nerve hypertrophy; and 5) presence of enhancement or diffusion restriction. Results: Eleven children with Krabbe disease and 12 children with MLD were included in this study. There was no significant difference in age or symptoms at onset. Periventricular and deep white matter signal alterations sparing the subcortical white matter were present in almost all patients of the two groups. More patients with Krabbe disease had T2 hyperintensities in the internal capsule and brainstem than patients with MLDs. In contrast, more patients with MLD had T2 hyperintensities in the splenium and genu of the corpus callosum. No patient with Krabbe disease showed T2 hyperintensity in the corpus callosal genu. A decrease in volume in the corpus callosum and thalamus was more frequently observed in patients with Krabbe disease than in those with MLD. Other MRI findings including the tigroid sign and optic nerve hypertrophy were not significantly different between the two groups. Conclusion: Signal abnormalities in the internal capsule and brainstem, decreased thalamic volume, decreased splenial volume accompanied by signal changes, and absence of signal changes in the callosal genu portion were MRI findings suggestive of Krabbe disease rather than MLD based on initial MRI. Other MRI findings such as the tigroid sign could not help differentiate between these two diseases.

• Investigative Magnetic Resonance Imaging
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• v.25 no.4
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• pp.338-344
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• 2021

Solitary fibrous tumors (SFT) are rare mesenchymal tumors that most commonly develop in the pleura; they rarely involve the diaphragm. MRI has not been widely used to evaluate SFTs of the thoracic cavity, though it may be highly useful in assessing local invasion, predicting malignant potential, and helping in the differential diagnosis. However, MRI findings of malignant SFTs of the diaphragmatic pleura have been described in only two cases. We report a rare case of a malignant solitary fibrous tumor of the diaphragmatic pleura in an 82-year-old man. We describe the clinical and characteristic imaging features, including computed tomography, conventional MRI, and diffusion-weighted imaging. Contrast-enhanced MRI is more accurate than is CT in identifying the origin of SFTs, predicting whether they ae benign or malignant, and assessing local invasion. This imaging modality proved helpful in deciding on the treatment strategy for these rare tumors.

• Journal of Veterinary Clinics
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• v.41 no.2
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• pp.133-138
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• 2024

An 8-year-old, spayed female Persian cat weighing 3.6 kg presented with a lumbosacral mass and bilateral weight bearing hindlimb lameness. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a dumbbell-shaped heterogeneous mass extending through the internal surface of the ileum and surrounding the lumbosacral junction. CT also revealed extensive osteoproliferation and bone lysis of the sacrum, but no evidence of any pulmonary metastasis. Furthermore, MRI revealed a focal area in the spinal cord showing connection with the adjacent tumor, suggesting tumor invasion into the spinal cord. Low-grade myxoid chondrosarcoma was histopathologically diagnosed. This is the first report describing CT and MRI findings of spinal cord chondrosarcoma in veterinary medicine. This study suggests that combining CT with MRI is a more sensitive tool for evaluating spinal tumors than using CT or MRI alone.

• Investigative Magnetic Resonance Imaging
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• v.3 no.1
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• pp.28-40
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• 1999

MRI는 주로 부인과 질환의 진단에 이용되어 왔으나 뛰어난 연조직 대조도와 다면 영상 능력으로 남성 골반강의 평가에서도 그 활용이 점차 확대되고 있다. 남성 골반강 MRI는 전립선을 중심으로 발전되어 왔으나 음경과 음낭, 요도 등을 침범한 외상, 종양 등의 질환에 매우 유용하므로 이들 부위에서의 MRI 이용이 더욱 증가할 것으로 보인다. 여기서는 전립선, 음경, 음낭 등의 남성 골반강 장기를 평가하는데 필요한 검사기법, 정상 해부학, 이상 질환의 MRI 소견 등에 대해 기술하고자 한다.

• Journal of Veterinary Clinics
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• v.34 no.2
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• pp.152-155
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• 2017

A 5-year-old intact female Maltese dog was referred to us with a history of left side head tilt and ataxia. Based on magnetic resonance imaging (MRI) and cerebrospinal fluid analysis results, the patient was tentatively diagnosed to meningoencephalitis of unknown etiology (MUE). Clinical signs were gradually improved and diminished after imatinib mesylate plus prednisolone therapy. At 90 days after treatment, we performed MRI recheck and brain inflammatory lesions were significantly improved compared with initial MRI results. However, the present patient showed head turn and tetraparesis after anesthesia and euthanized according to client's request. This report describes the clinical findings, serial magnetic resonance imaging characteristics under imatinib mesylate treatment in a MUE case.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.1
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• pp.48-53
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• 2000

In this paper, we develop a TMS320C31 (60MHz) digital signal processor (DSP) board to synthesize gradient waveforms for Spiral Scan Imaging (SSI), which is one of the ultra fast magnetic resonance imaging (MRI) methods widely used. In SSI, accurate gradient waveforms are very essential to high quality magnetic resonance images. For this purpose, sampling rate for synthesizing the gradient waveforms is set twice as high as the data sampling rate. With the developed DSP boards accurate gradient waveforms are obtained. Ultra fast spiral scan imaging with the developed with the developed DSP board is currently under development.