• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.128-128
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• 2002

목적： Gamma-Variate Function을 이용하여 뇌 관류에 관련하는 새로운 재구성 영상 (CBV, CBF, MTT, TTP, BAT)을 산출할 수 있는 프로그램을 개발 및 평가 대상 및 방법： 뇌 관류와 관련한 정량적인 재구성 영상(CBV, CBF, MTT, TTP, BAT)을 얻기 위하여 Gamma-Variate Function을 이용한 Post-processing 프로그램을 개발하였다. 자기공명영상은 1.5T ＆ 3.0T Magnum (Medinus Co., Ltd.)을 사용하였으면, 개발된 프로그램 평가를 위해 스핀에코 -EPI 펄스시퀀스(TR 2000 ms, TE 80 ms, FOV 260 mm, matrix 92$\times$128)를 사용하여 관류강조영상을 획득하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.612-614
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• 1998

뇌정위 수술(Stereotactic Surgery)은 컴퓨터 단층영상과 자기공명 영상 같은 3차원 영상을 이용하여 뇌병변의 위치를 입체적으로 정확히 파악하여 정상 뇌에 대한 손상을 최소화하며 병변을 수술하는 기법이다. 본 논문에서는 수술 받을 환자의 컴퓨터 단층영상과 자기공명 영상 등 다양한 종류의 3차원 볼륨 데이터를 전처리한 다음 동일한 3차원 공간 내에서 정렬시켜 선택적 또는 동시적으로 3차원 영상을 가시화 하는 기법을 제안한다. 또한 3차원 영상에서 뇌정위 수술의 삽입점과 목표점을 지정할 수 있는 기능을 지원하며 수술 경로에 따른 가상 수술의 시뮬레이션을 통하여 수술 경로의 안전성을 검증할 수 있게 하였다.

• Proceedings of the Korean Magnestics Society Conference
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• 2017.05a
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• pp.200-200
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• 2017

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.101-101
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• 2001

목적： 침에 의한 진통 기전은 동양에서 경험이나 임상적으로 그 효능이 입증되어 왔으나 서양에서 요구하는 과학적인 접근 방법에 의한 증거가 매우 희박하며, 과학적인 접근이 매우 어려웠다. fMRI를 이용하여 뇌의 기능 영상을 관측함으로 그 증거를 제시하고자 한다. 대상 및 방법： 집게손가락에 특정시간동안 온도에 의한 자극을 주면서 기능적 뇌 영상을 받고 침 자극 전후의 활성 영역을 비교함으로써 침이 통증의 진통 기전에 효과가 있음을 보여 준다. 신뢰성 있는 데이터를 위해 여러 명의 영상을 평균하여 잡음을 제거하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.431-433
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• 1999

본 논문에서는 뇌의 자기공명(이하 MR로 줄임) 영상에서 양측 대뇌반구의 뇌백질과 뇌회백질의 추출에 관하여 연구하였다. MR 영상은 특정 장기에서 일정한 gray level 값을 유지하는 전산화단층촬영(이하 CT로 줄임) 영상과는 달리 사람마다 gray level 값이 다르며 한 사람에 대해서도 각 슬라이스에 따라 gray level 값이 다르므로 각 슬라이스별로 조직의 특성을 파악하여 백질과 회백질의 추출에 이용하였다. 먼저 뇌를 둘러싸고 있는 두피, 근육, 두개골과 함께 안구를 제거한 후 두 개강 내에 위치한 뇌간과 소뇌의 특성을 차례로 인식하여 대뇌반구로부터 분리한 후 제거하였다. 또한 추출된 대뇌의 영상으로부터 백질과 회백질의 체적을 구하고, 뇌신경게 진단방사선과 전문의의 manual 작업과 비교하여 본 논문에서 제시한 방법의 정확도를 검증하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.06a
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• pp.95-98
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• 2001

본 논문은 뇌의 축방향(axial sect ion)에 대하여 촬영한 뇌의 자기공명 영상(Magnetic Resonance Imaging)을 대상으로 뇌의 영역만을 분리하기 위한 방법을 제안하고 있다. MR영상은 슬라이스마다 다른 분포값을 가지기 때문에 각 슬라이스 별로 조직의 특성을 파악하여 뇌의 영역을 분리하였다. 히스토그램의 명암값 분포를 분석하여 배경과 뇌를 둘러싸고 있는 외피를 제거하고 라벨링(label1ing) 알고리즘을 적용하여 뇌만 분리 할 수 있도록 하는 마스크 영상을 만들어 이것을 이용하여 원영상으로부터 뇌의 영역만을 분리하였다.

• The Korean Journal of Nuclear Medicine
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• v.31 no.3
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• pp.320-329
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• 1997

Neuroanatomic substrate of autism has been the subjects of continuing investigation. Because previous studies had not demonstrated consistent and specific neuroimaging findings in autism and most studies comprised adults and school-aged children, we performed a retrospective review in search of common functional and anatomical abnormalities with brain SPECT using Tc-99m ECD and correlative MRI The patient population was composed of 18 children aged 28 to 89 months(mean age : 55 months) who met the diagnostic criteria of autism as defined in the DSM-IV and CARS. Brain SPECT was performed after intravenous injection of 185-370MBq of Tc-99m ECD using brain dedicated annular crystal gamma camera. MRI was performed in all patients including T1, T2 axial and T1 sagittal sequences. SPECT data were visually assessed. Thirteen patients had abnormal SPECT scan revealing focal areas of decreased perfusion. Decreased perfusion of cerebellar vermis(12/18), cerebellar hemisphere(11/18), thalami(13/18), basal ganglia(4/18), posterior parietal(7/18), and temporal(4/18) area were noted on brain SPECT. Whereas, only 3 patients had abnormal MR findings which were subtle volume loss of parieto-occipital white matter in 3 and mild thinning of posterior body of corpus callosum in 2 and slightly decreased volume of cerebellar vermis in 1. Comparison of the numbers of abnormal findings revealed that regional cerebral blood flow (rCBF) abnormalities seen on SPECT were more numerous than anatomical abnormalities seen on MRI. In conclusion, extensive perfusion impairment involving cerebellum, thalami and parietal lobe were found in this study. SPECT may be more sensitive in reflecting pathophysiology of autism than MRI. However, further studies are mandatory to determine the significance of thalamic and parietal perfusion impairment in autism.

• Investigative Magnetic Resonance Imaging
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• v.12 no.1
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• pp.33-39
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• 2008

Purpose : There is debate concerning the observation of metabolite changes on MRS at the designated cortex during some tasks. The purpose of this study is to assess the change of the lactate content at the motor cortex during hand-grasping tasks with performing real-time fMRI-guided fMRS. Materials and Methods : Seven healthy volunteers (23-28 years old) underwent realtime fMRI during right hand grasping tasks with using a 1.5 T system. After confirming the activating area, single voxel MRS was preformed at 1) the baseline, 2) during the task and 3) after the task on the activating cortex. The three consecutive spectra were compared for observing the changes of the lactate content by the tasks. The Cho/Cr, NAA/Cr and Lac/Cr ratios were calculated manually from those spectra. Results : MRS during the tasks revealed the lactate peaks at the 1.33 ppm resonance frequency with great conspicuity at the activated area, which was identified on the real-time fMRI. After the task scan, the lactate peaks completely disappeared and the spectra recovered to the values of the baseline scan in all volunteers. At baseline, during the task and after the task, the Cho/Cr ratios were 0.81, 0.76 and 0.77, respectively, and the NAA/Cr ratios were 1.68, 1.65 and 1.72, respectively, and the Lac/Cr ratios were 0.28, 0.41 and 0.30, respectively. During the task, Lac was significantly increased by 46%. Conclusion : We observed prominent lactate peaks on MRS during hand-grasping tasks at the activated area, as was shown on the real-time fMRI. We suggest that fMRS can be used as a sensitive tool for observing the metabolite changes of the functioning brain.

• Sleep Medicine and Psychophysiology
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• v.25 no.2
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• pp.82-91
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• 2018

Objectives: Synchronous electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) has been used to explore sleep stage dependent functional brain networks. Despite a growing number of sleep studies using EEG-fMRI, few studies have conducted network analysis on whole night sleep due to difficulty in data acquisition, artifacts, and sleep management within the MRI scanner. Methods: In order to perform network analysis for whole night sleep, we proposed experimental procedures and data processing techniques for EEG-fMRI. We acquired 6-7 hours of EEG-fMRI data per participant and conducted signal processing to reduce artifacts in both EEG and fMRI. We then generated a functional brain atlas with 68 brain regions using independent component analysis of sleep fMRI data. Using this functional atlas, we constructed sleep level dependent functional brain networks. Results: When we evaluated functional connectivity distribution, sleep showed significantly reduced functional connectivity for the whole brain compared to that during wakefulness. REM sleep showed statistically different connectivity patterns compared to non-REM sleep in sleep-related subcortical brain circuits. Conclusion: This study suggests the feasibility of exploring functional brain networks using sleep EEG-fMRI for whole night sleep via appropriate experimental procedures and signal processing techniques for fMRI and EEG.

• Investigative Magnetic Resonance Imaging
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• v.16 no.2
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• pp.136-141
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• 2012

Purpose : To investigate the pharmacologic modulation of motor task-dependent physiologic responses by antiplatelet agent, clopidogrel, during hand motor tasks in healthy subjects. Materials and Methods: Ten healthy, right-handed subjects underwent three functional magnetic resonance (fMRI) sessions: one before drug administration, one after high dose drug administration and one after reaching drug steady state. For the motor task fMRI, finger flexion-extension movements were performed. Blood oxygenation level dependent (BOLD) contrast was collected for each subject using a 3.0 T VHi (GE Healthcare, Milwaukee, USA) scanner. $T2^*$-weighted echo planar imaging was used for fMRI acquisition. The fMRI data processing and statistical analyses were carried out using SPM2. Results: Second-level analysis revealed significant increases in the extent of activation in the contralateral motor cortex including primary motor area (M1) after drug administration. The number of activated voxels in motor cortex was 173 without drug administration and the number increased to 1049 for high dose condition and 673 for steady-state condition respectively. However, there was no significant difference in the magnitude of BOLD signal change in terms of peak T value. Conclusion: The current results suggest that cerebral motor activity can be modulated by clopidogrel in healthy subjects and that fMRI is highly senstive to evidence such changes.