• Journal of radiological science and technology
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• v.16 no.2
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• pp.19-26
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• 1993

Magnetic Resonance Image represents three-dimensional diagnostic imaging technique using both nuclear magnetic resonance phenomenon and computer. Compared with computed tomography (CT), MRI have advantages harmless to patient's body, three-dimensional image with high resolution and disadvantages long data acquisition time because of long T1 relaxation time, relatively low signal to noise ratio, high cost of setting, also. As physiologic motion of tissue results in motion ghost in MRI, high 2.0Tesla make improve low signal to noise ratio. This study have aim to improve image quality with controling motion ghost of tissue. Supposing a moving pixel in constant frequency, one pixel make two ghosts which are same size and different anti-phase. So, this study will show adjust parameter on locational control of motion ghost. Author made moving phantom replaced by respiratory movement of human, researched change of motion frequency, FOV by location shift, and them decided optimal FOV (field of view). The results are as follows: 1. The frequency content of the motion determines how far the image always appear in phase-encoding direction, the morphology of the ghost image is characteristic of the direction of the motion and its amplitude. 2. Double FOV of fixed signal object for locational control of motion ghost is recommended. Decreasement of spatial resolution by increasing FOV can compensate on increasing of matrix in spite of scan time increasement.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.69-72
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• 2000

This paper shows the more improved design of MRI receiver compared to conventional one based on Elscint Spectrometer. At first, the low-cost ADC is 16 bits, 3MHz sampling A/D converter Comparing to conventional one with signal bits of 14 bits, this device with those of 16 bits helps getting Improved the image resolution improved. If frequency is designed centering around 7.6 MHz to be satisfied in 10 MHz of maximum input bandwidth of ADC. For 1st demodulation, fixed IF is used for the purpose of the implementing multi nuclei system. Control parts & partial digital parts are integrated on one chip(FPGA). In DDC(Digital Down Converter), we got required bandwidth of LPF by controlling its decimation rate. With above considerations, we designed optimal receiver for high resolution imaging to be implemented through PC interface & experimental test of receiver of MRI after receiver's fabrication.

• Journal of Korean Neurosurgical Society
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• v.57 no.1
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• pp.58-60
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• 2015

A 15-year-old female patient with progressive pulsatile exophthalmos caused by intraorbital encephalocele was evaluated with computed tomography (CT) and magnetic resonance imaging (MRI) in our clinic. She had no history of trauma or reconstructive surgery. When she was a little girl, she had undergone surgery for congenital glaucoma on the right eye. On the three-dimensional image of CT, a hypoplasic bone defect was observed in the greater wing of the right sphenoid bone. MRI and CT scan showed herniation through this defect of the arachnoid membrane and protruded cerebral tissue into the right orbita. Intraorbital encephalocele is an important entity that can cause pulsatile exophthalmos and blindness.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.67-72
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• 2007

A post-processing program based on the OOP(Object-Oriented Programming) concept has been developed for visualization of MRI. User-friendly GUl(Graphic User Interface) has been built on the base of MFC(Microsoft Foundation Class). The program is organized as modules by classes based on VTK-library, and these classes are made to function through inheritance and cooperation which are an important and valuable concept of object-oriented programming. The major functions of this post-processor program are introduced and demonstrated, which include contour plot, surface plots, cut plot and clip plot as well as view manipulation (translation, rotation, scaling etc).

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.73-76
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• 2000

본 논문은 의료 영상 검색 시스템에서 뇌 MRI 이미지 데이터베이스에서 사용자의 질의를 만족하는 질의 결과 집합에 대한 시각화 방안을 제안한다. 한 환자의 뇌 MRI 이미지를 검색 결과로 제시할 경우 종류별, 방향별로 다양하고 여러 환자의 경우에는 그 양이 더욱 방대해진다. 이러한 뇌 MRI 이미지를 공간 제약적인 화면에 표현하는데는 한계가 있다. 따라서 본 논문에서는 질의 결과를 제시할 대 유사도가 높은 순서로 나열하고, 사용자 요구에 따른 관련 이미지를 종류와 방향별로 제시하여 이미지 조작을 가능하게 한다. 도한, 제시된 뇌 MRI 이미지를 효율적으로 브라우징할 수 있도록 3차원 블록 메타포어를 이용한 시각화 인터페이스를 통하여 공간 활용도의 향상과 사용자 인터페이스의 편의성 및 인지도를 증진한다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.601-603
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• 2002

MRI 스캔중 촬상 대상물의 화강평면내에서의 회전은 MRI 신호에 위상오차와 불균일 표본화를 일으킨다. 따라서, 아티팩트가 포함된 MR 화상의 화질열화를 개선하기 위하여 다음과 같은 방법들을 제안한다. 우선, 미리 주어진 회전파라메타써 쌍일처 보간과 중첩 특성을 이용해서 k 공간 불균일 표본화 데이터를 수정하는 알고리즘과, 2차원 회전운동의 회전각은 이미 알려져 있고, 회전중심 위치가 미지인 경우에 대해 위상보정에 기초한 아티팩트를 보정하는 알고리즘 및 회전중심과 각도가 모두 미지인 2차원 회전운동에 대해 아티팩느를 보정하는 알고리즘을 제안한다. 이 때, 미지운동 파라메타를 예측하기 위해 찰상대상물의 경계바깥쪽에서 이상적인 MR 화상의 에너지는 최소가 되고, 활상 대상물의 회전이 존재할 때 측정된 에너지가 증가한다는 성질을 이용했다. 이러만 성질을 이용해서 시뮬레이션 화상에 적용한 결과 제안한 방법에 대한 유효성을 확인하였다.

• Journal of Digital Convergence
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• v.12 no.10
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• pp.385-390
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• 2014

This research is conducted to identify whether an m-DIXON technique which is useful for an abdomen MRI examination compared with an existing e-THRIVE technique is a clinically useful or not. There was evaluated quantitative and qualitative to 84 subjects who had abdomen MRI exam due to their liver disease were conducted during a period from September in 2013 to February in 2014. First of all the quantitative evaluation, the m-DIXON technique's SNR was $90.42{\pm}16.90$ and the e-THRIVE technique was $60.42{\pm}11.54$ and the m-DIXON technique's CNR was $52.38{\pm}22.58$ and the e-THRIVE technique was $46.31{\pm}20.25$. Secondly in the qualitative evaluation, the m-DIXON technique's image quality was $4.06{\pm}0.34$, a artifact was $3.64{\pm}0.22$, and fat suppression was $4.16{\pm}0.15$, the e-THRIVE technique's image quality was $3.14{\pm}0.35$, a artifact was $3.06{\pm}0.38$, fat suppression was $3.14{\pm}0.30$. In conclusion, m-DIXON technique for abdomen MRI examination showed superiority over both SNR as a quantitative anaylsis, CNR and a qualitative analysis.

• Korean Journal of Radiology
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• v.20 no.1
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• pp.114-125
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• 2019

Objective: Segmented cardiac cine magnetic resonance imaging (MRI) is the gold standard for cardiac ventricular volumetric assessment. In patients with difficulty in breath-holding or arrhythmia, this technique may generate images with inadequate quality for diagnosis. Real-time cardiac cine MRI has been developed to address this limitation. We aimed to assess the performance of retrospective electrocardiography-gated real-time cine MRI at 3T for left ventricular (LV) volume and mass measurement. Materials and Methods: Fifty-one patients were consecutively enrolled. A series of short-axis cine images covering the entire left ventricle using both segmented and real-time balanced steady-state free precession cardiac cine MRI were obtained. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), and LV mass were measured. The agreement and correlation of the parameters were assessed. Additionally, image quality was evaluated using European CMR Registry (Euro-CMR) score and structure visibility rating. Results: In patients without difficulty in breath-holding or arrhythmia, no significant difference was found in Euro-CMR score between the two techniques (0.3 ± 0.7 vs. 0.3 ± 0.5, p > 0.05). Good agreements and correlations were found between the techniques for measuring EDV, ESV, EF, SV, and LV mass. In patients with difficulty in breath-holding or arrhythmia, segmented cine MRI had a significant higher Euro-CMR score (2.3 ± 1.2 vs. 0.4 ± 0.5, p < 0.001). Conclusion: Real-time cine MRI at 3T allowed the assessment of LV volume with high accuracy and showed a significantly better image quality compared to that of segmented cine MRI in patients with difficulty in breath-holding and arrhythmia.

• Journal of The Korean Radiological Technologist Association
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• v.28 no.1
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• pp.371-371
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• 2002

• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.817-824
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• 2007

Tractography using Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) is a method to determine the architecture of axonal fibers in the central nervous system by computing the direction of the principal eigenvector in the white matter of the brain. However, the fiber tracking methods suffer from the noise included in the diffusion tensor images that affects the determination of the principal eigenvector. As the fiber tracking progresses, the accumulated error creates a large deviation between the calculated fiber and the real fiber. This problem of the DT-MRI tractography is known mathematically as the ill-posed problem which means that tractography is very sensitive to perturbations by noise. To reduce the noise in DT-MRI measurements, a tensor-valued median filter which is reported to be denoising and structure-preserving in fiber tracking, is applied in the tractography. In this paper, we proposed the modified gradient descent method which converges fast and accurately to the optimal tensor-valued median filter by changing the step size. In addition, the performance of the modified gradient descent method is compared with others. We used the synthetic image which consists of 45 degree principal eigenvectors and the corticospinal tract. For the synthetic image, the proposed method achieved 4.66%, 16.66% and 15.08% less error than the conventional gradient descent method for error measures AE, AAE, AFA respectively. For the corticospinal tract, at iteration number ten the proposed method achieved 3.78%, 25.71 % and 11.54% less error than the conventional gradient descent method for error measures AE, AAE, AFA respectively.