• Progress in Medical Physics
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• v.21 no.4
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• pp.348-353
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• 2010

The purpose of this study was to explore the potentials of a clinical 3T MRI in mouse brains and technical adaptation and optimization. T1-weighted images (T1WI), T2-weighted images (T2WI), FLAIR (Fluid Attenuated Inversion Recovery) images, Gadolinium enhanced T1-weighted images (Gd-T1WI), Diffusion weighted images (DWI) were acquired in brain of 2 mice (weight 20~25 g) with cerebral infarction by occlusion of right middle cerebral artery, 1 hour, 24 hours, 72 hours after infarction and 1 normal mouse brain using clinical 3T MRI scanner. We analyzed differentiation of striatum, ventricle, cerebral cortex, and possibility of detection of acute cerebral infarction. We could differentiate the striatum, ventricle, cerebral cortex on T2WI and on DWI, FLAIR, T1WI, the differentiation of each anatomy of brain was not definite, but acute cerebral infarction was detected on DWI of 1 hour, 24 hours, 72 hours after infarction and on T2WI, FLAIR of 24 hours, 72 hours after infarction. Clinical 3T MRI can be used in differentiation of anatomy of mouse brains and DWI can be helpul in detection of acute cerebral infarction in acute phase. With technical adaptation and optimization clinical 3T MRI can be useful tool for provide preclinical and clinical small animal studies.

• Journal of the Korean Society of Radiology
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• v.84 no.2
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• pp.372-385
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• 2023

Breast cancer is one of the most common cancers and causes several complications in females. Currently, MRI is a necessary method for preoperative studies in patients with breast cancer. A high frequency of breast MRI can lead to an increase in the number of incidental extramammary findings. Moreover, it can provide accurate preoperative workup; therefore, the prognosis of patients can be improved. Herein, we provide several extramammary findings, including the mediastinum, lung, upper abdomen, bone, and soft tissue, correlating with US, chest CT, liver MRI, PET-CT, and bone scan.

• Investigative Magnetic Resonance Imaging
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• v.14 no.1
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• pp.41-46
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• 2010

Purpose : To evaluate the role of magnetic resonance imaging (MRI) in the diagnosis of papillary lesions of the breast. Materials and methods : Among 45 papillary lesions diagnosed at ultrasonography-guided core biopsy (USCB), 27 benign papillary lesions in 22 patients who underwent breast MRI were reviewed. The excsional biopsy was performed in 1-10 days after MRI was done. In MRI findings, lesions were considered suspicious if they show irregular, rim enhancement, or linear enhancement in morphologic evaluation, or washout enhancement pattern of delayed phase in dynamic enhancement characteristics. Diffusionweighted images were analyzed according to visibility of lesions. MRI findings were correlated with pathologic results at excisional biopsy. Results : At excisional biopsy, two lesions (9%) were diagnosed malignant in 22 benign papillary lesions without atypia by USCB and 4 (80%) were malignant in 5 benign papillary lesions with atypia by USCB. Among 18 lesions detected on MRI, 16 lesions showed suspicious findings on MRI, 11 lesions (69%) were diagnosed as benign and 5 (31%) were malignant. Among 12 lesions detected on diffusion weighted imaging, 10 lesions were diagnosed as benign and 2 were malignant. MRI findings were not significantly correlated with pathologic results at excisional biopsy. Conclusion : MRI findings were not useful to predict malignancy in benign papillary lesions diagnosed at USCB, because MRI findings of these were mostly suspicious (88.9%, 16/18). The benign papillary lesion should be included in the false positive lesion on breast MRI.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.13-14
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• 2023

뇌의 전기적 신경활동을 측정하는 뇌전도(EEG)는 저렴하게 취득할 수 있고 높은 시간 해상도를 갖는 반면 공간적 정보를 제공하지는 않는다. 기능적 자기공명영상(fMRI)은 혈류변화를 감지하여 뇌활동을 측정하는 방식으로서 높은 공간 분해능을 갖지만 고가의 비용과 설비를 요구한다. 최근 저렴하게 취득할 수 있는 EEG 데이터로부터 딥러닝을 사용하여 fMRI 합성영상을 생성하는 기술이 제안되었지만, 저주파수 대역에서 EEG와 fMRI 간의 뇌과학적 상관관계를 반영하지는 않는다. 본 연구에서는 휴식상태에서 취득된 EEG 데이터를 스펙트로그램으로 변환한 후 저주파수 특성을 사용하여 fMRI 합성영상을 생성하는 U-net 기반의 크로스 모달리티 변환 모델의 실현가능성을 평가하였다.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.63-71
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• 2008

• Proceedings of the Korean Information Science Society Conference
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• 2006.10b
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• pp.475-479
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• 2006

환자의 체동은 MRI에 의해 제공된 영상의 화질을 저하시키는 주된 원인이 되고 있다. 이에 본 논문에서는 MRI내 3차원 강체운동에 기인한 아티팩트를 제거하는 방법을 제안한다. 이러한 제거 목표를 달성하기 위해 MRI 영상 데이터를 얻기위한 2차원 다-슬라이스 방법(a multiple two dimensional slice technique)이 사용되어 왔다. 대상물체의 운동에 해당하는 수집된 MRI 데이터는 불균일한 표본화와 위상오차에 의해 영향을 받게된다. 3차원 강체운동에 대해 주어진 운동 파라메타와 장면간의 영향이라는 가정하에 양선형 보간법과 중첩법으로 다-슬라이스 데이터를 사용하는 방법에 기초한 재구성 알고리즘을 MRI 아티팩트를 제거하는데 사용한다. 미지의 체동 파라메타를 추정하기 위해 3차원 강체운동은 다-슬라이스 취득방법의 각 영상과 결합된 관심영역 바깥쪽에서 측정된 에너지를 증가시킨다는 사실을 이용하는 최소에너지법을 사용한다. 본 방법의 유효성을 확인하기 위해 3차원 강체운동에 의해 화질이 저하된 스핀-에코우 영상에 적용한 결과 화질이 식별될 수 있을 정도로 개선됨을 확인하였다.

• Journal of the Korean Society of Radiology
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• v.84 no.6
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• pp.1290-1308
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• 2023

Purpose To compare the diagnostic performance of rectal CT with that of high-resolution rectal MRI and histopathology in assessing rectal cancer. Materials and Methods Sixty-seven patients with rectal cancer who underwent rectal CT with rectal distension using sonographic gel and high-resolution MRI were enrolled in this study. The distance from the anal verge/anorectal junction, distance to the mesorectal fascia (MRF), extramural depth (EMD), extramesorectal lymph node (LN) involvement, extramural venous invasion (EMVI), and T/N stages in rectal CT/MRI were analyzed by two gastrointestinal radiologists. The CT findings of 20 patients who underwent radical surgery without concurrent chemoradiotherapy were compared using histopathology. Interclass correlations and kappa statistics were used. Results The distance from the anal verge/anorectal junction showed an excellent intraclass correlation between CT and MRI for both reviewers. For EMD, the distance to the MRF, presence of LNs, extramesorectal LN metastasis, EMVI, T stage, and intermodality kappa or weighted kappa values between CT and MRI showed excellent agreement. Among the 20 patients who underwent radical surgery, T staging, circumferential resection margin involvement, EMVI, and LN metastasis on rectal CT showed acceptable concordance rates with histopathology. Conclusion Dedicated rectal CT may be on par with rectal MRI in providing critical information to patients with rectal cancer.

• Journal of the Korean Society of Radiology
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• v.82 no.3
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• pp.562-574
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• 2021

MRI has the advantages of having excellent soft-tissue contrast and providing functional information without any harmful ionizing radiation. Although previous technical limitations restricted the use of chest MRI, recent technological advances and expansion of insurance coverage are increasing the demand for chest MRI. Recognizing the need for guidelines on appropriate use of chest MRI in Korean clinical settings, the Korean Society of Radiology has composed a development committee, working committee, and advisory committee to develop Korean chest MRI justification guidelines. Five key questions were selected and recommendations have been made with the evidence-based clinical imaging guideline adaptation methodology. Recommendations are as follows. Chest MRI can be considered in the following circumstances: for patients with incidentally found anterior mediastinal masses to exclude non-neoplastic conditions, for pneumoconiosis patients with lung masses to differentiate progressive massive fibrosis from lung cancer, and when invasion of the chest wall, vertebrae, diaphragm, or major vessels by malignant pleural mesothelioma or non-small cell lung cancer is suspected. Chest MRI without contrast enhancement or with minimal dose low-risk contrast media can be considered for pregnant women with suspected pulmonary embolism. Lastly, chest MRI is recommended for patients with pancoast tumors planned for radical surgery.

• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.9-14
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• 2021

Recently, magnetic resonance imaging (MRI), which can acquire images with good contrast without exposure to radiation, has been widely used for diagnosis. However, noise that reduces the accuracy of diagnosis is essentially generated when acquiring the MR images, and by adjusting the parameters, the noise problem can be solved to obtain an image with excellent characteristics. Among the parameters, the number of excitation (NEX) can acquire images with excellent characteristics without additional degradation of image characteristics. In contrast, appropriate NEX setting is required since the scan time increases and motion artifacts may occur. Therefore, in this study, after fixing all MRI parameters through the MRiLab simulation program, we tried to evaluate the tendency of image characteristics according to changing NEX through quantitative evaluation of brain T2 weighted images acquired by adjusting only NEX. To evaluate the noise level and similarity of the acquired image, signal to noise ratio (SNR), contrast to noise ratio (CNR), root mean square error (RMSE) and peak signal to noise ratio (PSNR) were calculated. As a result, both noise level and similarity evaluation factors showed improved values as NEX increased, while the increasing width gradually decreased. In conclusion, we demonstrated that an appropriate NEX setting is important because an excessively large NEX does not affect image characteristics improvement and cause motion artifacts due to a long scan.

• Journal of the Korean Society of Radiology
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• v.83 no.6
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• pp.1229-1239
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• 2022

Recently, artificial intelligence (AI) technology has shown potential clinical utility in a wide range of MRI fields. In particular, AI models for improving the efficiency of the image acquisition process and the quality of reconstructed images are being actively developed by the MR research community. AI is expected to further reduce acquisition times in various MRI protocols used in clinical practice when compared to current parallel imaging techniques. Additionally, AI can help with tasks such as planning, parameter optimization, artifact reduction, and quality assessment. Furthermore, AI is being actively applied to automate MR image analysis such as image registration, segmentation, and object detection. For this reason, it is important to consider the effects of protocols or devices in MR image analysis. In this review article, we briefly introduced issues related to AI application of MR image acquisition and reconstruction.