• Title/Summary/Keyword: magnetic resonace imaging

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Physical Principles of Magnetic Resonance Imaging in Animal (동물에서 자기 공명 영상 진단의 물리적 원리)

  • 김종규
    • Journal of Veterinary Clinics
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    • v.16 no.1
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    • pp.75-79
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    • 1999
  • Magnetic resonance imaging (MRI) is an imaging technique used to produce high quality images of the inside of the animal body. MRI is based on the principles of nuclear magnetic resonance (NMR) and started out as a tomographic imaging technique, that is it produced an image of the NMR signal in a thin slice through the animal body. The animal body is primarily fat and water, Fat and water have many hydrogen atoms. Hydrogen nuclei have an NMR signal. For these reasons magnetic resonance imaging primarily images the NMR signal from the hydrogen nuclei. Hydrogen protons, within the body align with the magnetic field. By applying short radio frequency (RF) pulses to a specific anatomical slice, the protons in the slice absorb energy at this resonant frequency causing them to spin perpendicular to the magnetic field. As the protons relax back into alignment with the magnetic field, a signal is received by an RF coil that acts as an antennae. This signal is processed by a computer to produce diagnostic images of the anatomical area of interest.

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Intracranial ipoma : CT and MRI Findings

  • Lee, Jong-Deok;Choi, Chang-Min
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.19 no.3
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    • pp.830-833
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    • 2005
  • Intracranial lipomas are rare lesions, which are believed to be congenital malformations. They are usually asymptomatic incidental findings and localized in the midline. However, they may occasionally produce neurological symptoms such as seizure, headache, mental changes, paresis. Currently, diagnosis of intracranial lipomas is made on based of imaging modalities, particularly Magnetic resonance imaging(MRI). Because Lipomas are strongly adherent to the surroundings and typically enclose both vessels and nerves, Surgical approach is rarely indicated.

Design of Z-directional gradient coil to improve gradient linearity for the nuclear magnetic resonace imaging(NMRI) (경사자장의 선형성 향상을 위한 핵자기공명 영상용 Z-방향 경사자기장 코일 설계)

  • Ko, Rock-Kil;Lee, Dong-Hoon;Baek, Seung-Tae;Kim, Song-Hui;Kwon, Young-Kil;Ryu, Kang-Sik
    • Proceedings of the KIEE Conference
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    • 1998.07a
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    • pp.235-237
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    • 1998
  • Gradient coil offers the spatial informations of sample or patient in Nuclear Magnetic Resonance Imaging(NMRI) and its gradient field linearity over the field of view(FOV) has many influence on the MR imaging. Accurate and good quality MR imaging can be acquired by the high gradient field linearity over the FOV. So it is an important part to design of gradient coil with good linearity in the wide imaging range. Usually, Z-directional gradient field is generated by using the Helmholtz type coil which is consisted of one-pair loop with anti-current path. It gets less about 40% linearity of the diameter spherical volume(DSV). In this study, we calculated optimized geometrical parameters of two-pair loop system to cancel odd terms up to $B_7$ included effectively. we also analyzed and compared the gradient field distribution and linearity of the common Helmholtz coil with them of the two-pair loop system.

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The Study of Lipid Proton Composition Change in a Rat Model of High Fat Diet Induced Fatty Liver by Magnetic Resonance Spectroscopy Analysis (고지방식이 유도성 지방간 쥐 모델에서 간의 자기공명분광 분석을 이용한 지질 양성자 조성 변화 연구)

  • Kim, Sang-Hyeok;Yu, Seung-Man
    • Journal of radiological science and technology
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    • v.44 no.4
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    • pp.315-325
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    • 2021
  • The purpose of this study is to investigate the changes in lipid proton (LP) composition according to the induced obese fatty liver and to use it as basic data for treatment and diagnosis of fatty liver in the future. The phantom study was conducted to identify differences between STEAM and PRESS Pulse sequences in LP concentration. A high-fat diet (60%) was administered to eight Sprague-Dawley rats to induce obesity and fatty liver disease. Baseline magnetic resonance imaging /spectroscopy data were obtained prior to the introduction of high-fat diet, and data acquisition experiments were performed after eight weeks using procedures identical to those used for baseline studies. The six lipid proton metabolites were calculated using LCModel software. The correlation between the fat percentage and each LP, revealed that the methylene protons at 1.3 ppm showed the highest positive correlation. The α-methylene protons to carboxyl and diallylic protons showed negative correlation with fat percentage. The methylene proton showed the highest increase in the LP; however, it constituted only 71.86% of the total LP concentration. The methylene proton plays a leading role in fat accumulation in liver parenchyma.

Effects of Music Therapy on the Anxiety of Patients who Take the Magnetic Resonance Imaging(MRI) Test (음악요법이 자기공명영상(MRI) 검사시 환자의 불안에 미치는 영향)

  • Jeon, Byeong-Kyu;Yeo, Jin-Dong
    • The Journal of the Korea Contents Association
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    • v.11 no.6
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    • pp.289-301
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    • 2011
  • This study is a research based on the non-equivalent control group pretest-posttest design whose purpose is to examine the effects of music therapy on the anxiety of patients who take the magnetic resonance imaging(MRI) test and their feeling of discomfort during the test. "The first hypothesis that the experimental group who receive music therapy will be lower in score for anxiety during the MRI test than the control group who do not was supported because after the therapy, the experimental group was found significantly decreased in that score in comparison to the control group. "The second hypothesis that the experimental group who receive music therapy will be fewer in vital signs after the MRI test than the control group who do not" was rejected in terms of both systolic and diastolic blood pressure. But the same hypothesis was partially supported because the two groups showed a significant difference in pulse rate after the test. "The third hypothesis that the experimental group who receive music therapy will be less in the feeling of subjective discomfort during the MRI test than the control group who do not" was verified to find that the two groups were significantly different from each other in the feeling. Specifically, there was a significant difference between the two groups in only one sub-area of that feeling, that is, tension. These findings suggest that music therapy could be an alternative method which can effectively reduce the state anxiety of patients during the magnetic resonace imaging(MRI) test.

THE STUDY ON ANTERIOR DISPLACEMENT OF DISK IN PATIENTS OF TEMPOROMANDIBULAR JOINT INTERNAL DERANGEMENT IN MAGNETIC RESONACE IMAGING (측두하악관절 내장증 환자의 자기공명영상에서 관절 원판의 전방 이동에 관한 연구)

  • Moon, Chang-Soo;Cho, Byoung-Ouck;Lee, Yong-Chan;Lee, Han-Ouck;You, Han-Shick;Lee, Yul
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.15 no.3
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    • pp.189-197
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    • 1993
  • Tempormandibular Joint pain and dysfunction is a common and important clinical problem. With the recent advances in imaging technology, radiologists have made major contribution to the understanding of TMJ disease. The MRI has several advantages over the conventional imaging methods. It is possible to obtain surprisingly precise images of internal hard and soft tissues with MRI. It is not invasive without ionizing radiation. The abnormal disk position has been thought as the cause of TMJ internal derangement. But there are few methods to relate disk position to TMJ internal derangement quantatively. The object of our study is to determine the amount of anterior displacement fo articular disk in symptomatic patients related each symptoms. Using the method of Dr. Drace, we studied the 38 joints of 22 persons with susceptable TMJ internal derangement. 1. In determining the anterior displacement of TMJ articular disk, the junction between the posterior band and bilaminar zone was useful. 2. The mean anterior displacement of disk in reduction group and without reduction group were $51.0^{\circ}C$ and $81.1^{\circ}C$ respectively. The difference was significant. 3. In the mean anterior displacement of disk, the pain without clicking group showed $84.8^{\circ}C$ and the clicking and pain group $70.8^{\circ}C$, the clicking group respectively.

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