1.5T MR 영상에서 Phantom을 이용한 Susceptibility Artifact 감소 효과 연구 = A Stud on Effect of Susceptibility Artifact Reduction with Use of Phantom in 1.5T MR Image

다국어 초록 (Multilingual Abstract)

Geometric transformation of magnetic field occurs in MRI scan that is conducted for patient who have underwent fixation with non-magnetic material screw, which lead to generation of susceptibility artifact in image. It was reported that susceptibility artifact appeared differently according to change in frequency encoding gradient direction. Against this background, the purpose of this study was to conduct experiment to examine and compare the degree of image distortion depending on frequency direction when susceptibility artifact was generated and these experiments results could be useful in clinical practice. The study method was to manufacture phantom which is titanium-contained and non-magnetic material screw that was inserted to investigate the degree of distortion in region of interest (ROI) depending change in frequency encoding gradient direction. QD extremity coil was used to set the ROI before images were obtained as frequency direction was changed from anterior to posterior and from right to left in axial scan, from right to left and from superior to inferior in coronal scan, and from superior to inferior and from anterior to posterior in sagittal scan, which aimed at comparing and investigating degree of distortion in the ROI depending on change in frequency encoding gradient direction (equipment used: MRI Signal l.5T by GE, TR/TF : 600/9 m/sec, matrix size: 512×192, slice thickness : 3 mm, Gab: 0.5 mm). According to the study results, the degree of distortion in the ROI which is depending on generation of susceptibility artifact that showed difference with change in frequency direction in axial scan. But in coronal scan, the distortion degree showed a bigger difference in the direction from superior to inferior than in the direction from right to left. In sagittal scan, the distortion degree showed a bigger difference in the direction from superior to inferior than in the direction from anterior to posterior. Such distortion degree in the ROI could be confirmed with the naked eye when phantom was used to change frequency direction. In MRI scan, when titanium-contained and non-magnetic material screws were inserted, image distortion was obtained due to generation of susceptibility artifact appeared differently according to frequency direction. Based on the results of this experiment, it is believed that image can be obtained with reduction of image distortion effect by susceptibility artifact if frequency direction is properly changed according to a body part to be examined in scan.