• 한국기계가공학회지
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• 제11권4호
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• pp.46-50
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• 2012

Stainless steel and titanium used for orthopedic prosthetic metal, magnetic resonance imaging was measured quantitatively the extent of distortion. Based on reading tests at varying metal magnetic resonance imaging (MRI) were investigated. To two image acquisition conditions for having three metal bodies mutually quantitative it compared analyzed the image of cross direction and the image of lengthwise. As for the distortion of the magnetic resonance image, as for the distortion of image it became small in the order of Clip, Strainless and Titanium. In addition, with T1WI and T2WI which are image acquisition condition T2WI the distortion of image became small. As for the distortion of the image by the metal, you could see the distortion of image in elliptical shape, the metal a bigger image distortion appeared in many parts. If clinical doctor has the condition of the same operation, use the Titanium material, it can, raising the diagnostic value of magnetic resonance image inspection after the operating from Stainless.

• Investigative Magnetic Resonance Imaging
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• 제22권4호
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• pp.205-208
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• 2018

The purpose of this study is to establish an appropriate protocol for breast magnetic resonance imaging (MRI) in the discipline of image quality standards. The intention of the protocol is to increase effectiveness of medical image information exchange involved in construction, activation, and exchange of clinical information for healthcare.

• 디지털콘텐츠학회 논문지
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• 제11권1호
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• pp.73-78
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• 2010

PROPELLER 확산강조영상기법이 금속에 의해 발생한 magnetic susceptibility artifact를 제거 할 수 있는지를 알아보고자 하였다. 뇌 MRI를 촬영한 환자 중에서 치아에 금속성 이물질을 가지고 있는 환자 20명을 대상으로 3.0T MR scanner를 이용하여 b value 0, 1000 s/mm2을 기준으로 에코 평면확산강조영상, PROPELLER 확산강조영상과 각각의 ADC map영상을 획득한 후 양쪽 측두엽, 뇌교, 안와등 네 부위에서 발생한 magnetic susceptibility artifact의 발생률을 비교 하였다.에코평면 확산강조영상 기법에서 금속물질이 있는 경우 magnetic susceptibility artifact가 발생되어 진단에 큰 제한점을 두었지만 PROPELLER 확산강조영상기법은 magnetic susceptibility artifact를 감소함으로써 임상적으로 정확한 진단에 도움이 될 것으로 생각된다.

• 한국자기학회지
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• 제27권1호
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• pp.35-40
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• 2017

기존의 광학현미경을 분해 하여 Kerr 현미경을 구성한 다음, 180도 자벽을 가지는 극박 3 %Si-Fe에 대해 자구모양을 관찰하였다. CCD 카메라로 취득한 한 단 한 장의 디지털 자구모양으로부터 자구영역의 경계선을 고가의 고속 영상처리장치 없이 결정하였다. 자구모양의 경계선 결정 방법은 디지털 자구모양의 픽셀값을 감산, 적분, 최소자승법의 연산을 이용하는 것이다. 이 방법은 많은 디지털 이미지를 연속적으로 취득하여 다중 합산하는 종래의 방식보다는 비용이 적게 든다. 이 연구 결과로부터 3개의 경계선과 0.085[T]의 자속밀도가 구해져 시편의 중심부와 같이 $180^{\circ}$ 자벽 만이 형성되는 영역이라면 이 방법을 적용할 수 있다.

• 대한의용생체공학회:의공학회지
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• 제30권6호
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• pp.461-468
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• 2009

Magnetic resonance electrical impedance tomography (MREIT) enables us to perform high-resolution conductivity imaging of an electrically conducting object. Injecting low-frequency current through a pair of surface electrodes, we measure an induced magnetic flux density using an MRI scanner and this requires a sophisticated MR phase imaging method. Applying a conductivity image reconstruction algorithm to measured magnetic flux density data subject to multiple injection currents, we can produce multi-slice cross-sectional conductivity images. When there exists a local region of fat, the well-known chemical shift phenomenon produces misalignments of pixels in MR images. This may result in artifacts in magnetic flux density image and consequently in conductivity image. In this paper, we investigate chemical shift artifact correction in MREIT based on the well-known three-point Dixon technique. The major difference is in the fact that we must focus on the phase image in MREIT. Using three Dixon data sets, we explain how to calculate a magnetic flux density image without chemical shift artifact. We test the correction method through imaging experiments of a cheese phantom and postmortem canine head. Experimental results clearly show that the method effectively eliminates artifacts related with the chemical shift phenomenon in a reconstructed conductivity image.

• Journal of Mechanical Science and Technology
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• 제20권10호
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• pp.1691-1701
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• 2006

The scan type magnetic camera is proposed to improve the limited spatial resolution due to the size of the packaged magnetic sensor. An image of the scan type magnetic camera, ${\partial}B/{\partial}x$ image, is useful for extracting the crack information of a specimen under a large inclined mag netic field distribution due to the poles of magnetizer. The ${\partial}B/{\partial}x$ images of the cracks of different shapes and sizes are calculated by using the improved dipole model proposed in this paper. The improved dipole model uses small divided dipole models, the rotation and relocation of each dipole model and the principle of superposition. Also for a low carbon steel specimen, the experimental results of nondestructive testing obtained by using multiple cracks are compared with the modeling results to verify the effectiveness of ${\partial}B/{\partial}x$ modeling. The improved dipole model can be used to simulate the LMF and ${\partial}B/{\partial}x$ image of a specimen with complex cracks, and to evaluate the cracks quantitatively using magnetic flux leakage testing.

• 대한금속재료학회지
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• 제50권5호
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• pp.401-406
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• 2012

When viewed using a magnetic resonance imaging (MRI) system, invasive materials inside the human body, in many cases, severely distort the MR image of human tissues. The degree of the MR image distortion increases in proportion not only to the difference in the susceptibility between the invasive material and the human tissue, but also to the intensity of the magnetic field induced by the MRI system. In this study, by blending paramagnetic Ti particles with diamagnetic graphite, we synthesized $Ti_{100-x}C_x$ composites that can reduce the artifact in the MR image under the high-strength magnetic field. Of the developed composites, $Ti_{70}C_{30}$ showed the magnetic susceptibility of ${\chi}=67.6{\times}10^{-6}$, which corresponds to 30% of those of commercially available Ti alloys, the lowest reported in the literature. The level of the MR image distortion in the vicinity of the $Ti_{70}C_{30}$ composite insert was nearly negligible even under the high magnetic field of 4.7 T. In this paper, we reported on a methodology of designing new structural materials for bio-applications, their synthesis, experimental confirmation and measurement of MR images.

• Journal of Magnetics
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• 제18권3호
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• pp.311-316
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• 2013

Digital image processing has increasingly been implemented in nanostructural analysis and would be an ideal tool to characterize the morphology and position of self-assembled magnetic nanoparticles for high density recording. In this work, magnetic nanoparticles were synthesized by the modified polyol process using $Fe(acac)_3$ and $Pt(acac)_2$ as starting materials. Transmission electron microscope (TEM) images of as-synthesized products were inspected using an image processing procedure. Grayscale images ($800{\times}800$ pixels, 72 dot per inch) were converted to binary images by using Otsu's thresholding. Each particle was then detected by using the closing algorithm with disk structuring elements of 2 pixels, the Canny edge detection, and edge linking algorithm. Their centroid, diameter and area were subsequently evaluated. The degree of polydispersity of magnetic nanoparticles can then be compared using the size distribution from this image processing procedure.

• Investigative Magnetic Resonance Imaging
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• 제26권1호
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• pp.66-70
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• 2022

Paratesticular liposarcoma is a very rare tumor that is typically reported as isolated cases of or as components of larger studies of liposarcomas. Image findings are similar to those of other anatomic sites, but in less-common sites, their appearance may be less familiar, and they may be mistaken for other pathologies. In addition, atypical image findings of liposarcoma make diagnosis more difficult. Herein, we report on the case of a 45-year-old male patient who presented with a painless, palpable mass in the right scrotum. The patient was diagnosed with paratesticular liposarcoma by excisional biopsy.

• Investigative Magnetic Resonance Imaging
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• 제22권1호
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• pp.71-77
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• 2018

Purpose: To develop a two-dimensional (2D) image-based respiratory motion correction technique for free-breathing coronary magnetic resonance angiography (MRA). Materials and Methods: The proposed respiratory navigator obtained aliased a 2D sagittal image from under-sampled k-space data and utilized motion correlation between the aliased images. The proposed navigator was incorporated into the conventional coronary MRA sequence including the diaphragm navigator and tested in three healthy subjects. Results: The delineation of major coronary arteries was significantly improved using the proposed 2D motion correction (S/I and A/P) compared to one-dimensional (S/I) correction using the conventional diaphragm navigator. Conclusion: The 2D image-based respiratory navigator was proposed for free-breathing coronary angiography and showed the potential for improving respiratory motion correction compared to the conventional 1D correction.