• Investigative Magnetic Resonance Imaging
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• 제21권2호
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• pp.91-96
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• 2017

Purpose: To describe technical methods for functional magnetic resonance imaging (fMRI) study with arterial spin labeling (ASL) compared to blood oxygenation level-dependent (BOLD) technique and discuss the potential of ASL for research and clinical practice. Materials and Methods: Task-based (n = 1) and resting-state fMRI (rs-fMRI) (n = 20) were performed using ASL and BOLD techniques. Results of both techniques were compared. Results: For task-based fMRI with finger-tapping, the primary motor cortex of the contralateral frontal lobe and the ipsilateral cerebellum were activated by both BOLD and ASL fMRI. For rs-fMRI of sensorimotor network, functional connectivity showed similar results between BOLD and ASL. Conclusion: ASL technique has potential application in clinical and research fields because all brain perfusion imaging, CBF measurement, and rs-fMRI study can be performed in a single acquisition.

• Journal of Korean Neurosurgical Society
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• 제58권3호
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• pp.242-247
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• 2015

Objective : The purpose of this study is to determine whether the changes of contralateral sensorimotor cortical activation on functional magnetic resonance imaging (fMRI) can predict the neurological outcome among spinal cord injury (SCI) patients when the great toes are stimulated without notice. Methods : This study enrolled a total of 49 patients with SCI and investigated each patient's preoperative fMRI, postoperative fMRI, American Spinal Injury Association (ASIA) score, and neuropathic pain occurrence. Patients were classified into 3 groups according to the change of blood oxygenation level dependent (BOLD) response on perioperative fMRI during proprioceptive stimulation with repetitive passive toe movements : 1) patients with a response of contralateral sensorimotor cortical activation in fMRI were categorized; 2) patients with a response in other regions; and 3) patients with no response. Correlation between the result of fMRI and each parameter was analyzed. Results : In fMRI data, ASIA score was likely to show greater improvement in patients in group A compared to those belonging to group B or C (p<0.001). No statistical significance was observed between the result of fMRI and neuropathic pain (p=0.709). However, increase in neuropathic pain in response to the signal change of the ipsilateral frontal lobe on fMRI was statistically significant (p=0.030). Conclusion : When there was change of BOLD response at the contralateral sensorimotor cortex on perioperative fMRI after surgery, relief of neurological symptoms was highly likely for traumatic SCI patients. In addition, development of neuropathic pain was likely to occur when there was change of BOLD response at ipsilateral frontal lobe.

• Investigative Magnetic Resonance Imaging
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• 제14권2호
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• pp.115-120
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• 2010

목적 : 활성자극 파라다임을 사용한 기능적 자기공명영상 데이터에서 자발적 요동에 해당하는 저주파 BOLD 신호의 존재여부를 규명해 보고자 하였다. 대상 및 방법 : 20명의 여자 양궁선수들과 양궁 경험이 없는 23명의 여자들을 대상으로 finger-tapping 파라다임은 30초간의 운동기와 휴지기를 3회 반복하였다. 혈액산소수준의존(BOLD) fMRI 영상은 3.0 T MR 기기에서 경사자장 반향 EPI 영상을 해부학적 영상은 3차원 T1 강조영상을 사용하였다. 뇌활성화 차이는 SPM-5를 사용하여 분석하였고 저주파 요동성분을 찾기 위해 GIFT 프로그램을 사용하였다. 결과 : 두군 모두에서 finger-tapping에 따라 대뇌좌측의 주운동영역과 보조운동영역 그리고 우측 소뇌에서의 활성화가 관찰되었다. GIFT를 사용한 ICA 분석에서 피검자들의 반측 감각운동망, 동측 감각운동망 그리고 인지기능과 연관된 신경망에 해당하는 독립적인 성분들이 구별되었다. 결론 : Finger-tapping fMRI 데이터에서 BOLD 신호의 자발적 요동에 해당하는 저주파 신호 성분들을 ICA 기법을 사용하여 분리해 낼수 있었고 이러한 독립성분들이 일차운동감각 신경망 그리고 운동 인지기능을 담당하는 신경망의 휴지기 신경활동을 나타낸다는 사실을 규명할 수 있었다.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.104-104
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• 2001

Purpose： In this study, we investigated the possible motor pathways of hemiplegic stroke patients usin combined TMS and BOLD fMRI approach and evaluated the correlation between TMS a fMRI methods. Method： Four subjects, who demonstrated left hemiplegia after stroke, are included. TMS was performed using a Dantec Mag2 stimulator (Dantec Company, USA) in single puls mode with figure eight-shaped coil. Following TMS localization, The BOLD T2＊-weight images were acquired with echo planar imaging sequence (TR = 1.2 sec, TE = 60 msec, and flip angle = 90). Motor activation was studied by means of a repetitive fing flexion-extension task. The stimulation protocol comprised 10 cycles of alternating activati and rest (10 images per cycle). Total 60 cycles were performed and each cycle take abou 1.5 sec. The resulting images were then analyzed with STIMULATE (CMRR, U, o Minnesota) to generate functional maps using a student t-test (p < 0.0005) and cluste analysis.

• Journal of Acupuncture Research
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• 제21권6호
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• pp.177-186
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• 2004

Introduction : Recent studies Suggested that there is a strong correlation between acupuncture stimulation and its related cortical activation. Anther study showed that either positive or negative BOLD effects could be observed depending on anatomical structure in acupuncture stimulation. In ttis study, we investigated a new acupoint $KI_6$ (照海), which was known as motor-related acupoint and obtained an evidence that the stimulation of $KI_6$ resulted in either negative or positive BOLD response to stimulation. Methods & Results : 1. Subjects and paradigms : Two separate stimulation paradigms were performed on five healthy (aged 22-23 yrs) in this study. First, the paradigm of acupuncture stimulation was that the acupuncture needle was inserted in acupoints $KI_6$, which is located in lateral side of the foot and then continuously twisted(補瀉를 除外한 捻轉法) for 70 seconds for 10 cycles of activation. During rest period (70 seconds), the needle was completed removed from acupoint. Total 60 cycles were performed and 10 images were obtained per cycle. Second, nonacupoint was randomly selected and the same paradigm was performed as acupoint stimulation. The stimulation protocol comprised 10 cycles of alternating. activation and rest (10 images per cycle). Total 60 cycles were performed and each cycle take about 1.5 sec for motor task. Subjects take an at least 15 minutes break before starting anther paradigm. 2. fMRI mapping : Multi-slice functional images were obtained on a 1.5T Magnetom Vision MRI scanner (Simens Medical, Erlangen, Germany) equipped with high performance whole-body gradients. The BOLD T2 * - weighted images were acquired with acho planar imaging sequence (TR = 1.2 sec, TE = 60 msec, and flip angle = $90_{\circ}$). The other sequence parameter are : FOV = 210 mm, matrix=$64{\times}128$ or $64{\times}64$, slice number=10 and slice thickness = 5 or 8 mm. the anatomic images were obtained with Spin-echo T1-weighted images. The resulting images were then anaiyzed with STIMULATE (CMRR, U. of Minnesota) to generate functional maps using a student T-test (p < 0.005) and cluster analysis. Both positive and negative response were evaluated. Conclusions : We have observed the activation of the motor cortex by stimulating motor-related acupoint ($KI_6$). Among five subjects, negative BOLD response was shown in four and positive response in one. All subjects showed positive response to conventional finger flexion-extension task. To understand the detailed mechanisms of correlation between acupuncture stimulation and BOLD fMRI changes and two typs of response, further study strongly required.

• 한국의학물리학회지:의학물리
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• 제30권1호
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• pp.22-31
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• 2019

Purpose: To develop a new diffusion-based functional MRI (fMRI) sequence to generate apparent diffusion coefficient (ADC) maps in single excitation and evaluate the contribution of b0 signal on neuronal changes. Materials and Methods: A diffusion-based fMRI sequence was designed with single measurement that can acquire images of three directions at a time, obtaining $b=0s/mm^2$ during the first baseline condition (b0_b), followed by 107 diffusion-weighted imaging (DWI) with $b=600s/mm^2$ during the baseline and visual stimulation conditions, and another $b=0s/mm^2$ during the last activation condition (b0_a). ADC was mapped in three different ways: 1) using b0_b (ADC_b) for all time points, 2) using b0_a (ADC_a) for all time points, and 3) using b0_b and b0_a (ADC_ba) for baseline and stimulation scans, respectively. The fMRI studies were conducted on the brains of 16 young healthy volunteers using visual stimulations in a 3T MRI system. In addition, the blood oxygen level dependent (BOLD) fMRI was also acquired to compare it with diffusion-based fMRI. A sample t-test was used to investigate the voxel-wise average between the subjects. Results: The BOLD data consisted of only activated voxels. However, ADC_ba data was observed in both deactivated and activated voxels. There were no statistically significant activated or deactivated voxels for DWI, ADC_b, and ADC_a. Conclusions: With the new sequence, neuronal activations can be mapped with visual stimulation as compared to the baseline condition in several areas in the brain. We showed that ADC should be mapped using both DWI and b0 images acquired with the same conditions.

• 대한의용생체공학회:의공학회지
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• 제28권3호
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• pp.338-343
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• 2007

BOLD T2*-weighted MR images reflects cortical blood flow and oxygenation alterations. fMRI study relies on the detection of localized changes in BOLD signal intensity. Since fMRI measures the very small modulations in BOLD signal intensity that occur during changes in brain activity, it is also very sensitive to small signal intensity variations caused by physiologic noise during the scan. Due to the complexity of movement of various organs associated with heart beat, it is important to reduce cardiac related noise rather than other physiological noise which could be required with relatively simple method. Therefore, a number of methods have been developed for the estimation and reduction of cardiac noise in fMRI study. But, each method has limitation. In this study, we proposed a new estimation method for brain activities influenced by blood pulsation effect using regression analysis with blood pulsation signal and the correspond slice of fMRI. We could find out that the right anterior cingulate cortex and right olfactory cortex and left olfactory cortex were largely influenced by blood pulsation effect for new method. These observed areas are mostly on the structure of anterior cerebral artery in the brain. That is convinced with that our method would be valid and our new method is easier to apply in practice and reduce computational burden than the retrospective method.

• 대한의용생체공학회:의공학회지
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• 제22권2호
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• pp.157-163
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• 2001

본 논문에서는 후취자극 제어장치를 이용하여 후각자극에 대한 인간의 뇌의 활성화 영역을 뇌기능자기공명영상(functional magnetic resonance imaging : fMRI)장치로 측정 또는 가시화하고 이의 임상적용에 대한 기초자료를 마련하고자 하였다. 우선 후각에 이상이 없고 코 수술 경험이 없는 오른손잡이 피험자 4명을 대상으로 5번에 걸쳐 Echo Plannar Imaging(EPI)에 의한 혈액산소농도의존(blood oxygen level dependent : BOLD)법을 이용하여 후각자극에 의한 뇌기능자기공명영상 실험을 수행하였다. 후각자극은 MRI 장치에서 사용할 수 있도록 제작된 후취제어장치를 사용하였으며, 제시된 향은 천연 향의 일종인 lavender-like fragrance를 사용하였다. 향의 제시는 후각의 피로도를 감안하여 3회의 휴식기관과 2회의 자극기간을 각 30초씩 번갈아 시행하였으며, 동시에 5초 간격으로 각 절편 당 30 영상을 연속적으로 획득하였다. Correlation법으로 0.4∼0.7의 문턱치(threshold)범위에서 통계 처리된 뇌의 활성화 영상은 EPI영상과 같은 부위의 T1 강조영상에 overlapping 시켰다. 호흡에 의한 artifact를 제거하기 위해 실험실에 만든 장치로 호흡을 측정하여 post-processing 할 때 반영하였다. 이렇게 얻어진 fMRI 영상의 신호변화를 관찰하여 활성 영역의 위치를 분석하였다. 그 결과 후각자극에 의해 뇌의 전두엽 피질(frontal cortex), 소뇌(cerebellum), 그리고 뇌교(pons)에서 활성화된 신호를 발견할 수 있었다. 또한, 측두엽(temporal lobe)과 뇌섬(insula)에서도 의미 있는 신호가 관찰되었다. 그러나, 일차 후각영역인 piriform cortex와 entorhinal cortex, amygdaloid complex, 그리고 이차후각영역인 orbitofrontal cotex에서는 그다지 많은 빈도로 신호가 발견되지 않았다. 결론적으로 BOLD법을 이용한 fMRI에 의하여 후각자극에 대한 뇌의 활성화영역을 관찰할 수 있었으며, 후각자극에 대한 뇌의 기능을 연구하는데 있어서 중요한 정량적 자료를 제공할 수 있다는 점을 확인할 수 있었다.

• Investigative Magnetic Resonance Imaging
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• 제1권1호
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• pp.66-74
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• 1997

혈액의 산소화와 불 산소화에 따른 국부적인 자화율 효과의 변화에 의한 자장의 불 균일성에 민감한 경사 자장 에코 기법은 현재의 뇌기능 MR 영상의 기본이 되고 있다. 일반적으로 이러한 경사 자장 에코기법은 $T2^{*}$ 혹은 BOLD효과에 의한 자장의 불 균일성의 증가가 신호의 감소로 나타난다. BOLD 효과는 주자장에 대한 핏줄의 방향이나 영상 형식, 즉, 횡단면, 관상면, 또는 시상면에 따라 달라진다. 그래서 영상 형식과 영상면에 대한 기울임 각에 따른 신호의 변화와 BOLD 효과의 변화에 대한 정량적인 연구를 하였다. 연구는 자화율 효과에 대해 다른 민감도를 가지는 TRFGE 와 CGE 기법으로 이루어졌다. 컴퓨터 모의 실험과 실험 결과를 본 논문에 나타내었다.

• 대한의용생체공학회:의공학회지
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• 제28권4호
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• pp.477-483
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• 2007

We have measured EOG and fMRI simultaneously to investigate whether eye movement (blinking mechanism) might influence functional magnetic resonance imaging (fMRI) signal response in the primary visual cortex. $T2^*-weighted$ Echo-Planar Imaging (EPI) with concurrent electrooculogram (EOG) was acquired in four subjects while they viewed a fixation point and a checkerboard with a flickering rate of 8Hz. With the help of EOG information we divided the experimental blocks into two different conditions: fixation and moving eye. We have compared the fMRI data of these two conditions. Our results have shown that there is no difference between these two conditions. This might suggest that eye blinking does not affect BOLD signal changes in the primary visual cortex. This means further that eye blinking can be ignored in data processing.