• The Korean Journal of Nuclear Medicine
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• v.37 no.1
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• pp.63-72
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• 2003

Functional MRI (fMRI) provides an indirect mapping of cerebral activity, based on the detection of the local blood flow and oxygenation changes following neuronal activity (Blood Oxygenation Level Dependent). fMRI allows us to study noninvasively the normal and pathological aspects of functional cortical organization. Each fMRI study compares two different states of activity. Echo-Planar Imaging is the technique that makes it possible to study the whole brain at a rapid pace. Activation maps are calculated from a statistical analysis of the local signal changes. fMRI is now becoming an essential tool in the neurofunctional evaluation of normal volunteers and many neurological patients as well as the reference method to image normal or pathologic functional brain organization.

• Investigative Magnetic Resonance Imaging
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• v.3 no.2
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• pp.167-172
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• 1999

Purpose : To evaluate the detection rate of hyperacute intracerebral hemorrhage in echo planar imaging (EPI) and other MR sequences. materials and Methods : Intracerebral hemorrhage was experimentally induced in ten rats. EPI, fast spin-echo (FSE) T2 weighted images, fluid attenuated inversion recovery (FLAIR), spin-echo (SE) T1 weighted images and gradient echo (GE) T1 weight ed images of rat's brains were obtained 2 hours after onset of intracerebral hemorrhage. EPI and FSE T2 images were additionally obtained 30 min and 1 hour after onset of hemorrhage in 3 and 6 rat, repeatedly, For objective visual assessment, discrimination between the lesion and normal brain parenchyma was evaluated on various MR sequences by three radiologists. For quantitative assessment, contrast-to-noise ratio (CNR) was calculated fro hemorrhage-normal brain parenchyma. Statistical analysis was performed usning the Wilcoxon-Ranks test. Results : EPI, FLAIR, and FSE T2 images showed high signal intensity lesions. The lesion discrimination was easier on EPI than on other sequences, and also EPI showed higher signal intensity for the subjective visual assessment. In quantitative evaluation, CNR of the hemorrhagic lesion versus normal brain parenchyma were higher on EPI and FLAIR images (p<0.01). There was no difference in CNR between EPI and FLAIR (p>0.10). On MR images obtained 30 minutes and 1 hour after the onset of intracerebral hemorrhage, the lesion detection was feasible on both EPI and FSE T2 images showing high signal intensity. Conclusion : EPI showed higher detection rate as compared with other MR sequences and could be useful in early detection and evaluation of intracerebral hemorrhage.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05c
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• pp.160-163
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• 2002

본 연구는 의료영상 중에 가장 많이 사용하는 의료 영상인 MR영상 중에서 머리 부위의 질병인 뇌종양에 대한 진단을 돕기 위한 연구이다. 뇌 MR영상의 T2강조 영상을 살펴보면, 종양 영역은 명암이 밝게 나타나고 종양 영역의 주변은 어둡게 나타나는 특성을 볼 수 있다. 따라서 제안된 방법은 뇌종양 특성인 명암의 밝기 정보를 기반으로 비정상 영역 내에서 명암 정보가 유사한 영역끼리 그룹화하고 그 중에 가장 밝은 영역을 종양 후보 영역으로 추출한 후 각 후보 영역들 중에서 MBR이 가장 큰 것을 종양으로 검출한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.389-392
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• 2003

MRI 영상은 뇌의 해부학적 정보와 기능적인 정보를 제공하는 유용한 도구이다. MR 뇌 영상은 2차원 영상뿐만 아니라 3차원 영상도 임상적으로 중요하다. MR 영상에서 뇌영역의 추출방법으로는 형태학적인 방법, 히스토그램을 이용한 방법, 에지 정보를 이용한 방법, 지식 기반을 이용한 방법들이 있다. 본 논문에서는 region growing을 이용하여 MR 영상에서 뇌 영역을 추출하였다. 3차원 가시화를 위하여 오픈 소스인 VTK를 이용하여 Ray Casting 알고리즘으로 구현하였다. 그리고 의료영상에서 사용되는 각종 단면을 3차원 뇌 영상에서 재구성하였다. 256×256 크기의 71 뇌MR 영상 70장을 이용하여 실험하였다. 향후 연구과제로 MR 영상에서 뇌 영역추출방법과 원영상의 전처리 과정의 연구가 필요하다.

• Proceedings of the KSMRM Conference
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• 1996.10a
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• pp.25-25
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• 1996

• Investigative Magnetic Resonance Imaging
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• v.15 no.2
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• pp.102-109
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• 2011

Purpose : To retrospectively evaluate the usefulness of diffusion-weighted images, ADC maps and conventional MR images for determination of brain tumor consistency. Materials and Methods : Twenty-three patients with brain tumor underwent MR examinations with T1, T2 and diffusion-weighted images. Regions of interest (ROIs) were drawn in the tumors, and the measured signal intensities (SI) were normalized with the contralateral side. We evaluated the correlation between SI ratios from various images and tumor consistency assessed at surgery. In three patients with both cystic and solid components, each component was evaluated independently. Qualitatively observed SIs were also correlated with tumor consistency. Results : Statistical analysis revealed significant correlation between tumor consistency and ADC ratio (r = -0.586, p = 0.002), SI ratios on T2-weighted images (r = -0.497, p = 0.010), and observed SIs on T2-weighted images (r = -0.461, p = 0.018). The relative ratio of ADC value correlated with tumor consistency most strongly. Conclusion : The measured ratio of ADC, SI ratio and observed SI grade on T2-weighted images can provide valuable information about the consistency of brain tumor.

• Journal of Korean Neurosurgical Society
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• v.61 no.4
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• pp.427-433
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• 2018

Obsessive compulsive disorder is a debilitating condition characterized by recurrent obsessive thoughts and compulsive reactions. A great portion of the obsessive compulsive disorder (OCD) patients are managed successfully with psychiatric treatment such as selective serotonin-reuptake inhibitor and cognitive behavioral psychotherapy, but more than 10% of patients are remained as non-responder who needs neurosurgical treatments. These patients are potential candidates for the neurosurgical management. There had been various kind of operation, lesioning such as leucotomy or cingulotomy or capsulotomy or limbic leucotomy, and with advent of stereotaxic approach and technical advances, deep brain stimulation was more chosen by neurosurgeon due to its characteristic of reversibility and adjustability. Gamma knife radiosurgery are also applied to make lesion targeting based on magnetic resonance (MR) imaging, but the complication of adverse radiation effect is not predictable. In the neurosurgical field, MR guided focused ultrasound has advantage of less invasiveness, real-time monitored procedure which is now growing to attempt to apply for various brain disorder. In this review, the neurosurgical treatment modalities for the treatment of OCD will be briefly reviewed and the current state of MR guided focused ultrasound for OCD will be suggested.

• Journal of radiological science and technology
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• v.31 no.4
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• pp.355-365
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• 2008

Purpose : This study isto determine the grade of brain tumor and compare the characteristics in each grade using in MRS (MR Spectroscopy). Method : STEAM (Stimulated Echo Acquisition Method) and protocol of PRESS (Point Resolved Spectroscopy) were used in the levels of tumor grade. We classified the pattern of tumor and analysis of the spectrum signals quantitatively from voxel in the brain tumor grade. In accordance with the result, we calculated the accuracy of biochemical. Result : In high-grade tumor, the NAA/Cr showed the signal reduction of 29.4% and 53.9%. However Cho/Cr increased 570% and 711%. However, in low-grade tumor, NAA/Cr downed to 42.6% and 58.1%. Cho/Cr increased to 188% and 195%. Conclusion : The study suggests that the comparative analysis of signals from MR spectroscopy could be useful to evaluate the grade of tumor and find out the characteristics of it. By extension, MR spectroscopy can be used for research with other organs in the human.

• Investigative Magnetic Resonance Imaging
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• v.19 no.3
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• pp.146-152
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• 2015

Purpose: The purpose of this study was to evaluate the associated brain parenchymal abnormalities of developmental venous anomalies (DVA) with susceptibility-weighted image (SWI). Materials and Methods: Between January 2012 and June 2013, 2356 patients underwent brain MR examinations with contrast enhancement. We retrospectively reviewed their MR examinations and data were collected as per the following criteria: incidence, locations, and associated parenchymal signal abnormalities of DVAs on T2-weighted image, fluid-attenuated inversion recovery (FLAIR), and SWI. Contrast enhanced T1-weighted image was used to diagnose DVA. Results: Of the 2356 patients examined, 57 DVAs were detected in 57 patients (2.4%); 47 (82.4%) were in either lobe of the supratentorial brain, 9 (15.7%) were in the cerebellum, and 1 (1.7%) was in the pons. Of the 57 DVAs identified, 20 (35.1%) had associated parenchymal abnormalities in the drainage area. Among the 20 DVAs which had associated parenchymal abnormalities, 13 showed hemorrhagic foci on SWI, and 7 demonstrated only increased parenchymal signal abnormalities on T2-weighted and FLAIR images. In 5 of the 13 patients (38.5%) who had hemorrhagic foci, the hemorrhagic lesions were demonstrated only on SWI. Conclusion: The overall incidence of DVAs was 2.4%. Parenchymal abnormalities were associated with DVAs in 35.1% of the cases. On SWI, hemorrhage was detected in 22.8% of DVAs. Thus, we conclude that SWI might give a potential for understanding of the pathophysiology of parenchymal abnormalities in DVAs.

• The KIPS Transactions:PartB
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• v.16B no.3
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• pp.195-202
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• 2009

In this paper, we propose the regions segmentation method of the white matter and the gray matter for brain MR image by using the ant colony optimization algorithm. Ant Colony Optimization (ACO) is a new meta heuristics algorithm to solve hard combinatorial optimization problem. This algorithm finds the expected pixel for image as the real ant finds the food from nest to food source. Then ants deposit pheromone on the pixels, and the pheromone will affect the motion of next ants. At each iteration step, ants will change their positions in the image according to the transition rule. Finally, we can obtain the segmentation results through analyzing the pheromone distribution in the image. We compared the proposed method with other threshold methods, viz. the Otsu' method, the genetic algorithm, the fuzzy method, and the original ant colony optimization algorithm. From comparison results, the proposed method is more exact than other threshold methods for the segmentation of specific region structures in MR brain image.