• Journal of the Korean Magnetics Society
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• v.20 no.4
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• pp.160-166
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• 2010

X-ray resonant magnetic scattering (XRMS) allows us to extract magnetic depth profiles in magnetic multilayers and magnetization distribution in magnetic nanostructures in element-specific manner using x-ray reflectivity and diffraction. XRMS is explained with a brief introduction and examples of magnetic structures and magnetic switching mechanism in magnetic multilayers and nanostructures.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.93-93
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• 2002

목적： 주자석의 자기장 안정도는 자기공명영상 시스템의 성능을 결정하는 요소 중의 하나이다. 영구자석형 MRI 시스템이 설치되는 병원 중 다수가 지하철, 자동차, 승강기 등의 외부 자기장 교란으로부터 상대적으로 가깝게 위치하고 있기 때문에 주자석의 자기장 안정도를 확보하기 힘들고, 그 영향에 기인한 artifact가 영상에 나타난다. 본 논문에서는 자기장 보상장치를 설계하여 자기장 교란에 대한 보상효과를 측정하였으며, 영상실험으로 영상의 품질이 개선되는 것도 확인하였다.

• Journal of the Korean Society of Radiology
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• v.84 no.2
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• pp.345-360
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• 2023

In Korea, the number of institutions providing breast MRI, as well as the number of breast MRIs, has recently increased. However, MRI-guided procedures, including biopsy and needle localization, are rarely performed compared to ultrasound-guided or stereotactic biopsy. As breast MRI has high sensitivity but limited specificity, lesions detected only on MRI require pathologic confirmation through MRI-guided biopsy or surgical excision with MRI-guided needle localization. Thus, we aimed to review MRI-guided procedures, including their indications, techniques, procedural considerations, and limitations.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.105-105
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• 2002

목적： 수소 자기 공명 분광기법은 자기공명 영상으로는 얻을 수 없는 화학적 성분에 대한 정보를 제공하여 암을 포함한 여러 질환의 진단과 예측에 사용된다. 이 기법으로는 어떤 특정한 작은 체적을 선택하여 그 부위에만 자기공명 분광신호를 획득하는 단일 체적기법과 체적 전체를 위상변화를 주면서 여기시킨 후, 데이터 후처리 과정에서 체적별로 분리해내는 다중체적기법이 있다. 다중체적기법은 더 긴 영상 획득시간에도 불구하고 단일 체적기법에 비하여 분광상을 대조군과 비교할 수 있는 잇점이 있다. 뇌를 진단하는데 사용하기 위한 수소분광선을 얻기 위하여 다중체적 화학적 영상기법을 개발하여 모형과 자원자에 대하여 적용하여 그 유용성 확인하였다.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.81-81
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• 2002

목적： 수소 핵 자기 공명 분광기법은 자기공명 영상으로는 얻을 수 없는 화학적 성분에 대한 정보를 제공하여 암을 포함한 여러 질환의 진단과 예측에 사용된다. 이 기법으로는 어떤 특정한 작은 체적을 선택하여 그 부위에만 자기공명 분광신호를 획득하는 단일 체적기법과 체적 전체를 위상변화를 주면서 여기 시킨 후, 데이터 후처리 과정에서 체적별로 분리해내는 다중체적기법이 있다. 다중체적기법은 더 긴 영상 획득시간에도 불구하고 단일 체적기법에 비하여 분광상을 대조군과 비교할 수 있는 잇점이 있다. 뇌를 진단하는데 사용하기 위한 수소분광선을 얻기 위하여 다중체적 화학적 영상기법을 개발하여 모형과 자원자에 대하여 적용하여 그 유용성 확인하였다.

• Investigative Magnetic Resonance Imaging
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• v.9 no.2
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• pp.117-133
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• 2005

For identifying the pathological findings in magnetic resonance images (MRIs), normal anatomical structures in MRIs should be identified in advance. For studying the anatomical structures in MRIs, a learning tool that includes the followings is necessary. First, MRIs of the entire body; second, horizontal, coronal, and sagittal MRIs; third, segmented images corresponding to the MRIs; fourth, three dimensional (3D) images of the anatomical structures in the MRIs; fifth, software incorporating the MRIs, segmented images, and 3D images. Such a learning tool, however, is hard to obtain. Therefore, in this research, such a learning tool which helps medical students and doctors study the normal anatomical structures in MRIs was made as follows. A healthy young Korean male adult with standard body shape was selected. Six hundred thirteen MRIs of the entire body were scanned (slice thickness 3 mm, interslice gap 0 mm, field of view 480 mm${\times}$480 mm, resolution 512${\times}$512, T1 weighted), and transferred to the personal computer. Sixty anatomical structures in the MRIs were segmented to make segmented images. Coronal, sagittal MRIs and coronal, sagittal segmented images were made. On the basis of the segmented images, forty-seven anatomical structures 3D images were made by manual surface reconstruction method. Software incorporating the MRIs, segmented images, and 3D images was composed. This learning tool that includes horizontal, coronal, sagittal MRIs of the entire body, corresponding segmented images, 3D images of the anatomical structures in the MRIs, and software is expected to help medical students and doctors study the normal anatomical structures in MRIs. This learning tool will be presented worldwide through Internet or CD titles.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.154-161
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• 1997

Purpose: Traumatic rupture of the diaphragm is not easy to diagnose and often delayed. Delayed diagnosis of diaphragmatic rupture accompanied by higher chances of strangulation of herniated viscera which may result in higher morbility and mortality. The purpose of this study was to evaluate diagnostic accuracy of spiral CT, MRI and US for the diagnosis of diaphragmatic rupture in an animal model. Materials and Methods: Small, medium, and large sized transabdominal diaphragmatic ruptures were surgically made in experimental rabbits and then followed up with spiral CT, MR!, and US at 1 day, 3 day, and 1 week after operation. Results: US was superior to MR! or spiral CT in diagnosis of diaphragmatic rupture(P(0.05). The sensitivity and specificity were 94.4% and 92.9% for US, 54.0% and 85.7% for MRI, and 46.0% and 78.6% for spiral CT, respectively. The size of laceration was not related to diagnostic sensitivity in US. Sensitivity of MRI and spiral CT increased as the size of laceration were larger, but no statistical significance was present(P>0.05). All experimental animals developed pleural effusion or hemothorax one day after operation. In acute phase, US and MRI were more sensitive than spiral CT in detecting diaphragmatic rupture. Spiral CT was more sensitive than US and MRI in delayed phase but without statistical significance(P>0.05). In the experimental rabbits with accompanying visceral hernia through the diaphragmatic defect, diagnostic accuracy was found equally high among three image modalities(P>0.05). Conclusion: This study indicates that US is the most accurate diagnostic method in detecting injury to the diaphragm in a rabbit model. The findings obtained in this experimental study can be applied to the diaphragmatic rupture of human being.

• Journal of the Korean Society of Radiology
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• v.82 no.5
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• pp.1218-1230
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• 2021

Purpose To compare the per-patient diagnostic performance of simulated abbreviated MRI (AMRI) to that of conventional MRI (CMRI) with full-sequence dynamic gadoxetic acid (GA) enhancement for early-stage hepatocellular carcinoma (HCC) screening in high-risk patients. Materials and Methods A total of 201 consecutive patients at high-risk for HCC, who underwent 3T liver MRI, were included in this retrospective study. The AMRI protocol comprised T2-weighted imaging, hepatobiliary phase imaging after GA injection, and diffusion-weighted imaging. For each patient, two AMRI and CMRI image sets were independently reviewed by two radiologists. Inter-reader agreement was assessed using Cohen's kappa value. A composite reference standard was used to determine the diagnostic performance of each image set for each reader. Results A total of 93 HCCs were detected in 79 patients. The inter-reader agreement was almost perfect for both image sets (κ = 0.839, 0.948). In AMRI, the per-patient sensitivity and negative predictive values (NPV) were 94.9% and 96.4%, respectively. In CMRI, the per-patient sensitivity and NPV were 96.2% and 97.5%, respectively. Conclusion AMRI, using only three sequences, had a comparable diagnostic performance to CMRI in screening early-stage HCC. AMRI could be an alternative HCC screening tool for high-risk HCC patients.

• Proceedings of the KSMRM Conference
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• 1999.11a
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• pp.48-48
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• 1999

• Investigative Magnetic Resonance Imaging
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• v.18 no.2
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• pp.176-181
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• 2014

Primary non-Hodgkin lymphoma (NHL) of the breast is a very rare disease, and the mammographic and ultrasonographic findings of breast lymphoma are variable. There are several reports of magnetic resonance (MR) imaging findings in patients with breast lymphomas; however, few reports have described the findings observed on MR spectroscopy or the features of diffusion weighted (DW) imaging. The authors report the findings of classical MR imaging, MR spectroscopy and DW imaging of a 48-year-old woman and a 40-year-old woman with primary non-Hodgkin's lymphoma of breasts. Mammography and breast ultrasonography revealed a mass with circumscribed margin. The mass showed strong enhancement after contrast injection on MR imaging. DW imaging showed reduced diffusion and high-amplitude choline (Cho) peak at 3.22 ppm was detected by single voxel MR spectroscopy which was consistent with malignancy.