• 제목/요약/키워드: MRI

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A Study on Utility of Magnetic Resonance Imaging for Female Pelvic Cavity using Enteral MRI Contrast Media (Enteral MRI contrast media를 이용한 여성골반 자기공명영상의 유용성)

  • Kim, Ham-Gyum
    • Journal of radiological science and technology
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    • v.20 no.1
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    • pp.29-34
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    • 1997
  • For radiological test in soft tissue or neighboring part with same signal intensity, proper test method and equipment shall be selected as needed. In case of female pelvic cavity, ultrasonography or computed tomography alternatively used, but MRI can be more usefully applied to design treatment method or operation plan by improving the diagnostic accuracy and careful observation of lesion characteristics. Magnetic Resonance Imaging using recently developed Enteral MRI contrast media can acquire more diagnostic information than using only intravenous contrast media. Thus this study attempted to examine the utility of anatomic structure and diagnostic acquisition by imaging the female pelvic cavity using Enteral MRI contrast media. As a result of analyzing magnetic resonance Imaging after administering Enteral MRI contrast media to pelvic cavity suspect patients, more diagnostic information media could be acquired than only using Intravenous contrast. Expecially, in the diagnosis of lesion position, shape, distinction from neighboring tissues it is thought that external Enteral MRI contrast media should be used.

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Detecting Active Brain Regions by a Constrained Alternating Least Squares Nonnegative Matrix Factorization Algorithm from Single Subject's fMRI Data (단일 대상의 fMRI 데이터에서 제약적 교차 최소 제곱 비음수 행렬 분해 알고리즘에 의한 활성화 뇌 영역 검출)

  • Ding, Xiaoyu;Lee, Jong-Hwan;Lee, Seong-Whan
    • Proceedings of the Korean Information Science Society Conference
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    • 2011.06c
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    • pp.393-396
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    • 2011
  • In this paper, we propose a constrained alternating least squares nonnegative matrix factorization algorithm (cALSNMF) to detect active brain regions from single subject's task-related fMRI data. In cALSNMF, we define a new cost function which considers the uncorrelation and noisy problems of fMRI data by adding decorrelation and smoothing constraints in original Euclidean distance cost function. We also generate a novel training procedure by modifying the update rules and combining with optimal brain surgeon (OBS) algorithm. The experimental results on visuomotor task fMRI data show that our cALSNMF fits fMRI data better than original ALSNMF in detecting task-related brain activation from single subject's fMRI data.

Dynamic Lumbar Spinal Stenosis : The Usefulness of Axial Loaded MRI in Preoperative Evaluation

  • Choi, Kyung-Chul;Kim, Jin-Sung;Jung, Byung-Joo;Lee, Sang-Ho
    • Journal of Korean Neurosurgical Society
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    • v.46 no.3
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    • pp.265-268
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    • 2009
  • Two cases of dynamic lumbar spinal stenosis were identified by the authors using axial loaded magnetic resonance image (MRI). In both cases, the patients presented with neurogenic claudication but MRI in decumbency showed no definite pathologic condition associated with their symptoms. In contrast, axial loaded MRI demonstrated constrictive spinal stenosis and a significantly decreased dural sac caused by epidural fat buckling and thickening of the ligamentum flavum in both cases. In the second case, a more prominent disc protrusion was also demonstrated compared with decumbent MRI. After decompressive surgery, both patients had satisfactory outcomes. Axial loaded MRI can therefore give decisive information in dynamic spinal disorders by allowing simulation of an upright position.

Cortical Dysplasia: Tc-99m ECD SPECT Findings and Comparative Study with MRI according to Pathologic Grading (뇌피질 이형성증: Tc-99m ECD SPECT 소견과 병리적 등급에 따른 MRI와 비교 연구)

  • Park, Soon-Ah;Lim, Seok-Tae;Sohn, Myung-Hee;Chung, Gyung-Ho
    • The Korean Journal of Nuclear Medicine
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    • v.35 no.1
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    • pp.23-32
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    • 2001
  • Purpose: Cortical dysplasia (CD) designates a diverse group of malformations resulting from one or more abnormalities in the development of the cerebral cortex. We investigated the findings of interictal SPECT and the diagnostic usefulness of interical and ictal SFECT according to pathological grading (PG) in comparison with MRI. Materials and Methods: This study included 16 patients (M:F=9:7, age: $19.9{\pm}11.8$ yrs) with pathologically proven CD. Tc-99m ECD SPECT was performed in all patients: interictal 11, interictal and ictal 3, ictal 2. MRI were obtained in all patients and image analysis was done blindly as to the result of SPECT. Pathologic findings of CD were classified into grade 1 G1, dyslamination), grade 2 (G2, dysplastic neurons) and grade 3 (G3, balloon cells). We compared SFECT with MRI in lesions-to-lesions and analyzed the result according to PG. Results: In SFECT and MRI. 38 and 27 lesions were visually recognized. In 14 interictal SPECT, variable findings in 35 lesions were demonstrated: 25 were hypoperfusion, 7 hyperperfusion, 2 heterotopic perfusion in the white matter. By comparison between two studios, missed lesions were founded: SPECT were 1 lesion, MRI 12. Review of missed 12 lesions of MRI were followed according to PG: G1 patients were 16.7% (4/19), G2 40.0% (6/15), and G3 50% (2/4). Conclusion: Interictal SFECT in CD showed variable findings such as hypoperfusion, hyperperfusion or heterotopic perfusion. However, for detection of missed CD on MRI, SFECT may help to detect a functional abnormality of the lesion with high PG.

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MRI Artifacts

  • 최순섭
    • Investigative Magnetic Resonance Imaging
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    • v.1 no.1
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    • pp.51-57
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    • 1997
  • MRI의 artifact는 대부분 신호의 부호화 방향에 따라서 방향성을 가지는데, 이를 요약해보면, 위상부호화 방향의 artifact에는 motion artifact, flow artifact, RF noise등이 있고, 주파수 부호화 방향의 artfact는 susceptibility artfact, chemical shift artifact, central line artifact등이 있으며, 양방향 모두 생길수 있는 것은 Aliasing artifact와 Gibb's phenomenon이고, 전체적으로 영샹의 질을 떨어뜨리는 것은 susceptibility artifact, Eddy current, cross talk등이 있다. 이런 artifact는 대부분은 MRI 자체의 물리적 특성에 다소간 기인하므로, artifact가 없는 양호한 영상을 얻기 위해서는 MRI의 설치 단계부터 관심이 필요하고, MRI의 기본원리와 다양한 artifact에 대해 이해함으로써, 제거 가능한 artifact는 제거하여 양질의 영상을 만들고 판독시의 오류를 피할 수 있도록 해야할 것이다.

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On the Implementation of Articulatory Speech Simulator Using MRI (MRI를 이용한 조음모델시뮬레이터 구현에 관하여)

  • Jo, Cheol-Woo
    • Speech Sciences
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    • v.2
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    • pp.45-55
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    • 1997
  • This paper describes the procedure of implementing an articulatory speech simulator, in order to model the human articulatory organs and to synthesize speech from this model after. Images required to construct the vocal tract model were obtained from MRI, they were then used to construct 2D and 3D vocal tract shapes. In this paper 3D vocal tract shapes were constructed by spatially concatenating and interpolating sectional MRI images. 2D vocal tract shapes were constructed and analyzed automatically into a digital filter model. Following this speech sounds corresponding to the model were then synthesized from the filter. All procedures in this study were using MATLAB.

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남성 골반강의 자기공명영상

  • 김보현
    • Investigative Magnetic Resonance Imaging
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    • v.3 no.1
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    • pp.28-40
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    • 1999
  • MRI는 주로 부인과 질환의 진단에 이용되어 왔으나 뛰어난 연조직 대조도와 다면 영상 능력으로 남성 골반강의 평가에서도 그 활용이 점차 확대되고 있다. 남성 골반강 MRI는 전립선을 중심으로 발전되어 왔으나 음경과 음낭, 요도 등을 침범한 외상, 종양 등의 질환에 매우 유용하므로 이들 부위에서의 MRI 이용이 더욱 증가할 것으로 보인다. 여기서는 전립선, 음경, 음낭 등의 남성 골반강 장기를 평가하는데 필요한 검사기법, 정상 해부학, 이상 질환의 MRI 소견 등에 대해 기술하고자 한다.

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Head Motion Detection and Alarm System during MRI scanning (MRI 영상획득 중의 피험자 움직임 감지 및 알림 시스템)

  • Pae, Chong-Won;Park, Hae-Jeong;Kim, Dae-Jin
    • Investigative Magnetic Resonance Imaging
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    • v.16 no.1
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    • pp.55-66
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    • 2012
  • Purpose : During brain MRI scanning, subject's head motion can adversely affect MRI images. To minimize MR image distortion by head movement, we developed an optical tracking system to detect the 3-D movement of subjects. Materials and Methods: The system consisted of 2 CCD cameras, two infrared illuminators, reflective sphere-type markers, and frame grabber with desktop PC. Using calibration which is the procedure to calculate intrinsic/extrinsic parameters of each camera and triangulation, the system was desiged to detect 3-D coordinates of subject's head movement. We evaluated the accuracy of 3-D position of reflective markers on both test board and the real MRI scans. Results: The stereo system computed the 3-D position of markers accurately for the test board and for the subject with glasses with attached optical reflective marker, required to make regular head motion during MRI scanning. This head motion tracking didn't affect the resulting MR images even in the environment varying magnetic gradient and several RF pulses. Conclusion: This system has an advantage to detect subject's head motion in real-time. Using the developed system, MRI operator is able to determine whether he/she should stop or intervene in MRI acquisition to prevent more image distortions.