• Journal of the Korea Computer Graphics Society
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• v.7 no.1
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• pp.37-49
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• 2001

We propose an optimization of mutual information for multiresolution image registration to represent useful information as integrated form obtaining from complementary information of multi modality images. The method applies mutual information as cost function to measure the statistical dependency or information redundancy between the image intensities of corresponding pixels in both images, which is assumed to be maximal if the images are geometrically aligned. As experimental results we validate visual inspection for accuracy, changning initial condition and addictive noise for robustness. Since our method uses the native image rather than prior feature extraction, few user interaction is required to perform the registration. In addition it leads to robust density estimation and convergence as applying non-parametric density estimation and stochastic multiresolution optimization.

• The Journal of Korean Institute of Next Generation Computing
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• v.15 no.5
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• pp.64-74
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• 2019

Although a non-rigid registration has high demands in clinical practice, it has a high computational complexity and it is very difficult for ensuring the accuracy and robustness of registration. This study proposes a method of applying a non-rigid registration to 3D magnetic resonance images of brain in an unsupervised learning environment by using a deep-learning network. A feature vector between two images is produced through the network by receiving both images from two different patients as inputs and it transforms the target image to match the source image by creating a displacement vector field. The network is designed based on a U-Net shape so that feature vectors that consider all global and local differences between two images can be constructed when performing the registration. As a regularization term is added to a loss function, a transformation result similar to that of a real brain movement can be obtained after the application of trilinear interpolation. This method enables a non-rigid registration with a single-pass deformation by only receiving two arbitrary images as inputs through an unsupervised learning. Therefore, it can perform faster than other non-learning-based registration methods that require iterative optimization processes. Our experiment was performed with 3D magnetic resonance images of 50 human brains, and the measurement result of the dice similarity coefficient confirmed an approximately 16% similarity improvement by using our method after the registration. It also showed a similar performance compared with the non-learning-based method, with about 10,000 times speed increase. The proposed method can be used for non-rigid registration of various kinds of medical image data.

• Korean Journal of Psychosomatic Medicine
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• v.25 no.1
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• pp.3-11
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• 2017

Objectives : The aim of this study was to draw attention toward so called 'behavioral variant frontotemporal dementia(bvFTD) phenocopy syndrome', which is difficult to discriminate with the primary psychiatric disorders, showing poor response to conventional therapeutic drugs, leading to higher risk to misdiagnoses and legal problems. Furthermore, the author insisted that our interest and study on them must be continued. Methods : English articles published during 2000 thru 2016 had been searched by internet with the combination of words such as 'frontotemporal', 'phenocopy' and 'behavioral', and reviewed. Besides, two clinical vignettes were described. Results : Precise diagnosis is important because patients' behavioral symptoms can influence on their families and community. However, disease-modifying treatment for bvFTD are not developed until now, and recent therapeutic drugs are only good for specific symptoms, while deterioration progresses in spite of proper psychiatric management. The possible bvFTD patients are not progressed into probable bvFTD clinically, showing no decline of cogntive and social function, no decrease of activity function, longer survival time, and normal neuroimaging for several years. Conclusions : Rather than expected, there are much more patients having clinical symptoms, course and diagnostic findings including neuroimaging, which are atypical to classical frontotemporal dementia and primary psychiatric disorders. If our knowledge and discriminating ability is improved, discovery rate of that cases will be increased. However, the identity of these atypical features are not clarified until now, it must be further actively investigated.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.157-168
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• 2020

Advancements in segmentation methodology has made automatic segmentation of brain structures using structural images accurate and consistent. One method of automatic segmentation, which involves registering atlas information from template space to subject space, requires a high quality atlas with accurate boundaries for consistent segmentation. The Allen Mouse Brain Atlas, which has been widely accepted as a high quality reference of the mouse brain, has been used in various segmentations and can provide accurate coordinates and boundaries of mouse brain structures for tractography. Through probabilistic tractography, diffusion tensor images can be used to map comprehensive neuronal network of white matter pathways of the brain. Comparisons between neural networks of mouse and human brains showed that various clinical tests on mouse models were able to simulate disease pathology of human brains, increasing the importance of clinical mouse brain studies. However, differences between brain size of human and mouse brain has made it difficult to achieve the necessary image quality for analysis and the conditions for sufficient image quality such as a long scan time makes using live samples unrealistic. In order to secure a mouse brain image with a sufficient scan time, an Ex-vivo experiment of a mouse brain was conducted for this study. Using FSL, a tool for analyzing tensor images, we proposed a semi-automated segmentation and tractography analysis pipeline of the mouse brain and applied it to various mouse models. Also, in order to determine the useful signal-to-noise ratio of the diffusion tensor image acquired for the tractography analysis, images with various excitation numbers were compared.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.251-254
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• 2001

본 논문에서는 Self Organizing Map을 이용하여 fMRI data를 분석해 보았다. fMRl (functional Magnetic Resonance Imaging)는 인간의 뇌에 대한 비 침투적 연구 방법 중 최근에 각광받고 있는 것이다. Motor task를 수행하고 있는 피험자로부터 image data를 얻어내어 SOM을 적용하여 clustering한 결과 motor cortex 영역이 뚜렷하게 clustering 되었음을 알 수 있었다.

• Proceedings of the KSMRM Conference
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• 1999.04a
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• pp.99-108
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• 1999

선천성 대사 이상은 다양한 뇌질환으로 나타낸다. 일반적으로 이 질환들은 하나 또는 둘이상의 대사경로에 대한 생화학적 이상에 원인이 있다. 정상적 생화학적 산물의 결핍이나 비정상적 산물의 축적에 의한 뇌기능 이상에 의해 임상증상이 나타내게 되는데 그 증상은 대개 경기, 경직성, 발육지연 등으로 비특이적이고 영상소견도 마찬가지로 비특이적이다. 대사 이상에 있어서의 신경병변은 일부 뇌백질을 주로 침범하는 경우를 제외하면 대부분 뇌백질을 침범하고 따라서 일반적으로 일차성 뇌백질 질환이 대사성 뇌질환을 일컫는다고 할 수가 있다. 뇌백질 질환은 뇌백질의 구성원중 가장 큰 부분을 차지하는 수초(myelin)를 침범하는 질환을 일컫는다. 중추신경계의 백질은 수초로 싸여있는 축삭(axon)과 선경교세포 (neuroglial cell) 및 혈관 등으로 구성되어 있으며, 이중 대부분을 수초가 차지하고 이 수초로 인하여 정상 뇌백질이 흰색을 나타낸다. 백질내의 신경교세포로는 성상세포 (astrocyte) 와 핍지세포 (oligodendrocyte)가 있으며 신 경교세포의 가장 중요한 기능은 핍지세포에 의한 축삭의 외피화 (ensheathment) 즉, 수초이다. 수초는 핍지세포의 세포질 돌기 (cytoplasmic process)의 일부이며 따라서 수초의 생존과 대사는 핍지세포와 운명을 같이한다. 일반적으로 세포의 생존, 대사와 가장 관련있는 기능은 세포질내에 함유되어 있는 구조물인 소기관(organelle)에 의하여 수행된다. 따라서, 비록 모든 소기관들이 백질 질환을 이르키는데 직접 연관되어 있지는 않더라도 수초의 생존과 대사에는 핍지세포의 소기관들이 매우 중요한 역할을 하게 된다. 세포질내 중요한 소기관으로는 세포 막, 미토콘드리아 (mitochondria), endoplasmic reticulum, Golgi 체, lysosome, peroxisome 그리고 세포질등이 있으며, 이들중에서 lysosomes, peroxisomes, 그리고 미토콘드리아가 특정한 유전성 백질질환에 중요한 역할을 하는 것이 밝혀졌다. 이러한 질환들은 최소한 각 소기관에 의한 질환군으로 분류될 수 있다.

• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.149-154
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• 1999

In anatomical aspects, magnetic resonance image offers more accurate information than other medical images such as X ray, ultrasonic and CT images. This paper introduces a method that segments and detects lesion for 2 dimensional axial MR brain images automatically. Image segmentation process consists of 2 stages. First stage extracts cerebrum region using thresholding and morphology. In the second stage, white matter, gray matter and cerebrospinal fluid in the cerebrum are extracted using FCM, We could improve processing time as removing uninterested region. Finally symmetry measure and anatomical Knowledge are used to detect lesion.

• Investigative Magnetic Resonance Imaging
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• v.14 no.2
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• pp.103-114
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• 2010

Purpose : To generate a Korean specific brain template, especially in patients with Alzheimer's disease (AD) by optimizing the voxel-based analysis. Materials and Methods : Three-dimensional T1-weighted images were obtained from 123 subjects who were 43 cognitively normal subjects and patients with 44 mild cognitive impairment (MCI) and 36 AD. The template and the corresponding aprior maps were created by using the matched pairs approach with considering differences of age, gender and differential diagnosis (DDX). We measured several characteristics in both our and the MNI templates, including in the ventricle size. Also, the fractions of gray matter and white matter voxels normalized by the total intracranial were evaluated. Results : The high resolution template and the corresponding aprior maps of gray matter, white matter (WM) and CSF were created with the voxel-size of $1{\times}1{\times}1\;mm$. Mean distance measures and the ventricle sizes differed between two templates. Our brain template had less gray matter and white matter areas than the MNI template. There were volume differences more in gray matter than in white matter. Conclusion : Gray matter and/or white matter integrity studies in populations of Korean elderly and patients with AD are needed to investigate with this template.

• Journal of the Korean Society of Radiology
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• v.81 no.5
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• pp.1053-1068
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• 2020

In accordance with the new healthcare policy of government (Moon Jae-In Care) to strengthen health insurance coverage, the National Health Insurance (NHI) coverage of brain magnetic resonance imaging (MRI), brain/neck MR angiography (MRA), and head and neck MRI have been expanded since 2018 in Korea. This article has been reviewed focusing on the "Detailed matter concerning criteria and method for providing reimbursed services in the NHI. Some revisions" regarding reimbursement for MRI, which was revised from October 2018 to April 2020 and is currently in effect. It included the MRI reimbursement system in Korea, recent adjustment of the reimbursement coverage for patients with headache or dizziness, and reimbursement coverage, standard imaging, and radiologic report of brain MRI, brain/neck MRA and head and neck MRI. This article could help radiologists gain knowledge on health insurance to protect the expertise of the radiologist and to play a leading role in the hospital. As the policy changes, detailed matter concerning criteria and method for providing reimbursed services in the NHI may be revised. Therefore, radiologists should update issues related to insurance reimbursement for MRI continuously.

• Journal of the Korean Society of Radiology
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• v.83 no.3
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• pp.453-472
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• 2022

Over the past decades, the immense clinical need for early detection methods and treatments for dementia has become a priority worldwide. The advances in PET biomarkers play increasingly important roles in understanding disease mechanisms by demonstrating the protein pathology underlying dementia in the brain. Amyloid-β and tau deposition in PET images are now key diagnostic biomarkers for the Alzheimer's disease continuum. The inclusion of biomarkers in the diagnostic criteria has achieved a paradigm shift in facilitating early differential diagnosis, predicting disease prognosis, and influencing clinical management. Furthermore, in vivo images showing pathology could become prognostic as well as surrogate biomarkers in therapeutic trials. In this review, we focus on recent developments in radiotracers for amyloid-β and tau PET imaging in Alzheimer's disease and other neurodegenerative diseases. Further, we introduce their potential application as future perspectives.