• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.313-316
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• 2002

본 연구에서는 기능적 자기공명 영상법(functional magnetic resonance imaging)을 이용하여, 한국어, 일어, 프랑스어, 영어 등 여러 언어를 구사할 수 있는 다중언어화자들을 대상으로 각 언어에 따른 대뇌 언어처리 과정을 알아보고, 그 처리과정이 해당언어의 유창성, 습득시기에 따라 어떻게 달라지는지를 알아보았다. 실험 결과, 언어처리에 있어 핵심적인 역할을 하는 것으로 보고되는 Broca 영역은 언어의 이해와 산출 과정에 모두 관계된 것으로 보이며, 언어의 산출과정에는 언어의 이해과정에 관계되는 영역외에 조음과정에 따른 영역의 활성화가 보고되었다. 또한 언어습득시기와 유창성에 따른 각 언어의 활성화를 살펴보면, 유창성이 높을수록 대뇌 활성화는 줄어들며, 유창성이 낮은 언어조건에서는 언어처리 영역의 활성화 수준이 높아지며 또한 우반구 및 전전두회(prefrontal gyrus)의 활성화가 높아지는 것이 보인다.

• Journal of radiological science and technology
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• v.16 no.2
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• pp.19-26
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• 1993

Magnetic Resonance Image represents three-dimensional diagnostic imaging technique using both nuclear magnetic resonance phenomenon and computer. Compared with computed tomography (CT), MRI have advantages harmless to patient's body, three-dimensional image with high resolution and disadvantages long data acquisition time because of long T1 relaxation time, relatively low signal to noise ratio, high cost of setting, also. As physiologic motion of tissue results in motion ghost in MRI, high 2.0Tesla make improve low signal to noise ratio. This study have aim to improve image quality with controling motion ghost of tissue. Supposing a moving pixel in constant frequency, one pixel make two ghosts which are same size and different anti-phase. So, this study will show adjust parameter on locational control of motion ghost. Author made moving phantom replaced by respiratory movement of human, researched change of motion frequency, FOV by location shift, and them decided optimal FOV (field of view). The results are as follows: 1. The frequency content of the motion determines how far the image always appear in phase-encoding direction, the morphology of the ghost image is characteristic of the direction of the motion and its amplitude. 2. Double FOV of fixed signal object for locational control of motion ghost is recommended. Decreasement of spatial resolution by increasing FOV can compensate on increasing of matrix in spite of scan time increasement.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1446-1447
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• 2015

In this paper, we developed the quantification software for evaluating the voxel-based cellular heterogeneity of gadoxetic acid-enhanced magnetic resonance imaging (MRI) in the liver. Our software is clinically applied to accurately quantify and interpret the alterations of liver functions in patients with hepatocellular carcinoma.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.111-115
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• 2017

Terahertz waves are superior to conventional X-ray or Magnetic Resonance Tomography(MRI), and the amount of information that can be transmitted is as large as thousands of times that conventional X-ray or MRI. In addition, Terahertz waves have great performance in analyzing an object which have some layered structure. By using this advantage, we can extract the letters of a page by analyzing information such as absorption amount and reflection amount by irradiating a closed book with pulses of various frequencies within gap of a terahertz wave. However, in the image of each page using the Terahertz wave might be obtained various kinds of noise and the different character occlusion region. So, to extract letters from the terahertz image, we must take the noise and occlusion region away. We have been working to enhancement the image quality in various ways, and keep on studying de-noising processing for enhancement about the image quality and high resolution. Finally, we also keep on studying about OCR(Optical Character Recognition) technology, which based on pattern matching technique, to read letters.

• Korean Journal of Radiology
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• v.25 no.1
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• pp.86-102
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• 2024

Early diagnosis, accurate assessment, and localization of peritoneal metastasis (PM) are essential for the selection of appropriate treatments and surgical guidance. However, available imaging modalities (computed tomography [CT], conventional magnetic resonance imaging [MRI], and 18fluorodeoxyglucose positron emission tomography [PET]/CT) have limitations. The advent of new imaging techniques and novel molecular imaging agents have revealed molecular processes in the tumor microenvironment as an application for the early diagnosis and assessment of PM as well as real-time guided surgical resection, which has changed clinical management. In contrast to clinical imaging, which is purely qualitative and subjective for interpreting macroscopic structures, radiomics and artificial intelligence (AI) capitalize on high-dimensional numerical data from images that may reflect tumor pathophysiology. A predictive model can be used to predict the occurrence, recurrence, and prognosis of PM, thereby avoiding unnecessary exploratory surgeries. This review summarizes the role and status of different imaging techniques, especially new imaging strategies such as spectral photon-counting CT, fibroblast activation protein inhibitor (FAPI) PET/CT, near-infrared fluorescence imaging, and PET/MRI, for early diagnosis, assessment of surgical indications, and recurrence monitoring in patients with PM. The clinical applications, limitations, and solutions for fluorescence imaging, radiomics, and AI are also discussed.

• Korean Journal of Radiology
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• v.21 no.4
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• pp.462-470
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• 2020

Objective: To demonstrate that human visual illusion can contribute to sub-endocardial dark rim artifact in contrast-enhanced myocardial perfusion magnetic resonance images. Materials and Methods: Numerical phantoms were generated to simulate the first-passage of contrast agent in the heart, and rendered in conventional gray scale as well as in color scale with reduced luminance variation. Cardiac perfusion images were acquired from two healthy volunteers, and were displayed by the same gray and color scales used in the numerical study. Before and after k-space windowing, the left ventricle (LV)-myocardium boarders were analyzed visually and quantitatively through intensity profiles perpendicular the boarders. Results: k-space windowing yielded monotonically decreasing signal intensity near the LV-myocardium boarder in the phantom images, as confirmed by negative finite difference values near the board ranging -1.07 to -0.14. However, the dark band still appears, which is perceived by visual illusion. Dark rim is perceived in the in-vivo images after k-space windowing that removed the quantitative signal dip, suggesting that the perceived dark rim is a visual illusion. The perceived dark rim is stronger at peak LV enhancement than the peak myocardial enhancement, due to the larger intensity difference between LV and myocardium. In both numerical phantom and in-vivo images, the illusory dark band is not visible in the color map due to reduced luminance variation. Conclusion: Visual illusion is another potential cause of dark rim artifact in contrast-enhanced myocardial perfusion MRI as demonstrated by illusory rim perceived in the absence of quantitative intensity undershoot.

• Investigative Magnetic Resonance Imaging
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• v.12 no.2
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• pp.115-122
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• 2008

Purpose : To evaluate the correlation between the radiological non-invasive hepatic fibrosis index (RNHFI), as determined by SPIO-enhanced MRI, and the laboratory non-invasive hepatic fibrosis index. Materials and Methods : Patients (99 total: 61 men and 38 women; mean age: 58 years) who underwent SPIO-enhanced MRI (1.5T) during 5 years included. These patients were subdivided into a liver cirrhosis group (LCG) and a non-liver cirrhosis group (non-LCG). Using PACS view, we measured the RNHFI (mean standard deviation of hepatic signal intensity (SD), noise-corrected coefficient of variation (CV)) of three ROIs in the liver parenchyma by SPIO-enhanced MRI. The laboratory non-invasive hepatic fibrosis index (AST-platelet ratio index (APRI)) of all patients was calculated from the laboratory data. We compared the RNHFI and APRI of LCG with those of non-LC group using Student's t-test. A bivariate correlation was performed to investigate the relationship between the RNHFI and APRI in the LCG. Results : For the LCG, mean values of SD and CV by SPIO-enhanced MRI were $10.3{\pm}3.7$ and $0.19{\pm}0.08$, respectively. For the non-LCG, mean values of SD and CV were $6.5{\pm}1.6$ and $0.08{\pm}0.05$, respectively. The mean APRI of the LCG and the non- LCG were $2.04{\pm}1.7$ and $0.32{\pm}0.32$, respectively. The RNHFI and APRI were significantly different between both groups (p<0.05). For the LCG, the bivariate correlation between SD and APRI revealed a statistically significant positive correlation (r=0.5, p<0.001). In both groups, there was no statistically significant correlation between CV and APRI. Conclusion: A measurement of SD can be a simple and useful method for the evaluation of hepatic fibrosis.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.384-390
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• 1994

Authors retrospectively compared the 99mTc MDP bone scans and corresponding MR imagings in 20 patients with histologically proven malignancy, Mean interval of the two studies was 16.6 days, Cancer diagnosis Included 8 lung, 2 each of colon, breast, stomach, 1 each of prostate, thyroid, malignant lymphoma and 3 adenocarcinoma of unknown primary site. Of the 105 regions compared, :t6 regions were positive for metastases in bone scans or MR imagings. 30 regions(65.2%) were positive by bone scan and 44 regions(95.7%) by MR imaging. 87 regions(82.9%) were concordantly positive or negative by bone scan and MR imaging, but 18 regions(17.1%) were discordant. In the discordant regions, 16 regions positive in MR imaging were negative in bone scan. The greatest number of discordant findings occured in the cervical region and in the patient with stomach cancer. Our results suggest that the sensitivity of MR Imaging is greater than that of bone scan in detecting spinal metastases. And bone scan is useful screening test of metastasis for evaluating entire skeleton including spine.

• Journal of the Korean Society of Radiology
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• v.82 no.1
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• pp.99-115
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• 2021

Various sequences have been developed for MRI to aid in the radiologic diagnosis. Among the various MR sequences, susceptibility-weighted imaging (SWI) is a high-spatial-resolution, three-dimensional gradient-echo MR sequence, which is very sensitive in detecting deoxyhemoglobin, ferritin, hemosiderin, and bone minerals through local magnetic field distortion. In this regard, SWI has been used for the diagnosis and treatment of various neurologic disorders, and the improved image quality has enabled to acquire more useful information for radiologists. Here, we explain the principle of various signals on SWI arising in neurological disorders and provide a retrospective review of many cases of clinically or pathologically proven disease or components with distinctive imaging features of various neurological diseases. Additionally, we outline a short and condensed overview of principles of SWI in relation to neurological disorders and describe various cases with characteristic imaging features on SWI. There are many different types diseases involving the brain parenchyma, and they have distinct SWI features. SWI is an effective imaging tool that provides complementary information for the diagnosis of various diseases.

• Journal of Oral Medicine and Pain
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• v.34 no.4
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• pp.409-420
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• 2009

The aim of this study was to investigate clinical assessment, panorama & MRI findings and cephalometric characteristics in 42 patients with condylar resorption, who visited in the Department of Oral Medicine Kyungpook National University Hospital at 2006. The results were as follows; 1. Clinical assessment 1) Female was 34 and male was 8, females were predominant. Distribution of age showed as follows; 10s was 14, 20s was 13, 30s was 7, 40s was 3, 50s was 4 and 60s was 1 patient. 10s and 20s were predominant. 2) Most of the patients had parafunctional habit. 2. Findings of panorama & MRI 1) Most of the patients had degree of Grade II condylar resorption by panorama taking. 2) Most of the patients had disc dislocation and belonged to the degree of stage IV by MRI taking. 3. Cephalometric Characteristics 1) SN, SAr and saddle angle in female patients were significantly smaller and SN in male patients showed only significantly smaller than normal group. 2) SNA showed no difference from the normal group in both patients. SNB was smaller and ANB was lager in female patients than normal group. 3) SN-GoMe and FMA increased in patients. 4) Total posterior facial height & ramus height were significantly smaller. 5) Mandibular body length did not show any significant difference.