• Imaging Science in Dentistry
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• 제31권4호
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• pp.185-192
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• 2001

Purpose: To evaluate the condylar movement at maximal mouth opening on MRI in patients with internal derangement. Materials and Methods: MR images and transcranial views for 102 TMJ s in 51 patients were taken in closed and maximal opening positions, and the amount of condylar movement was analyzed quantitatively and qualitatively. Results: For MR images, the mean condylar movements were 9.4 mm horizontally, 4.6 mm vertically and 10.9 mm totally, while those for transcranial views were 12.5 mm, 4.6 mm, and 13.7 mm respectively. The condyle moved forward beyond the summit of the articular eminence in 41 TMJs (40.2%) for MR images and 56 TMJs (54.9%) for transcranial views. Conclusion: The horizontal and total condylar movements were smaller in MR images than in transcranial views.

• 융합신호처리학회논문지
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• 제20권3호
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• pp.132-137
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• 2019

의료영상으로 생성된 데이터의 양은 전문적인 시각적 분석 한계를 점점 초과하여, 자동화된 의료영상 분석의 필요성이 증가되고 있는 실정이다. 이러한 이유 등으로 인하여 본 논문에서는 정상소견과 종양소견을 보이는 각각의 뇌 실질 MRI 의료영상을 이용하여 Inception V3 딥러닝 모델을 이용한 종양 유무에 따른 분류 및 정확도를 평가하였다. 연구 결과, 딥러닝 모델의 정확도 평가는 학습 데이터 세트의 경우 90%, 검증 데이터 세트의 경우 86%의 정확도를 나타내었다. 손실률 평가에서는 학습 데이터 세트의 경우 0.56, 검증 데이터 세트의 경우 1.28의 손실률을 나타내었다. 향 후 연구에서는 딥러닝 모델의 성능 향상 및 평가의 신뢰성 확보를 위하여 공개된 의료영상의 데이터를 충분히 확보하고, 라벨링 분류 작업을 통한 라벨링의 정확도를 개선하여 모델링을 구현해 볼 필요가 있다고 사료된다.

• 한국의학물리학회지:의학물리
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• 제24권1호
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• pp.68-75
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• 2013

본 연구의 목적은 26명의 건강한 검진자들을 대상으로 PET/CT와 PET/MRI의 전신 영상에서 조기 정밀/ 진단 수준을 향상하고자 관심부피를 이용하여 정상부위의 $SUV_{LBM}$-최대치를 이용하여 PET/CT와 PET/MRI를 조영제 사용 유무와 관계없이 동시 평가할 수 있는 데이터를 구축하고자 하였다. 전신 F-18 FDG PET/CT와 전신 F-18 FDG PET/MRI의 정상부위의 VOI를 이용한 $SUV_{LBM}$-최대치평가는 PET/CT를 기준으로 PET/MRI의 영상은 매우 유의한 차이를 보였다(p<0.0001). 그러나 통계학적으로 높은 상관관계를 가진다(R>0.8). PET/MRI의 $SUV_{LBM}$ 평가 시 26.3% 감소하여 판단할 것과 조영제를 사용할 경우는 29.3% 감소하여 판단할 것으로 생각한다. PET/CT와 PET/MRI의 모든 영상의 판독에서는 $SUV_{LBM}$-최대치를 사용하는 것이 편리성과 효율성을 고려하여 임상의나 연구자들에게 많은 도움이 되리라 판단된다.

• Imaging Science in Dentistry
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• 제36권2호
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• pp.73-79
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• 2006

Purpose : To describe the MRI findings of the antero-superior attachment of the disc in patients with internal derangement. Materials and Methods : One hundred fifty-six MR images from 40 normal subjects and 55 abnormal subjects were classified into three study groups of normal, anterior disc displacement with reduction and anterior disc displacement without reduction. On both closed- and open-mouth proton density sagittal images, the depiction of the antero-superior attachment of the disc and its demarcation from the disc were evaluated in three cuts of lateral, central and medial one thirds of the condyle. Results : The depiction of antero-superior attachment was more frequent by the order of normal, anterior disc displacement with reduction and anterior disc displacement without reduction groups, and the significant differences were found on lateral cut of the closed images and lateral and central cuts of the open images. In study for the demarcation between the antero-superior attachment and the disc the lateral cut of the closed images and all three cuts of the open images showed significant differences. Conclusion : Open images are useful to show the difference in depiction of the antero-superior attachment of the disc among the TMJ groups.

• 대한의용생체공학회:의공학회지
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• 제22권3호
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• pp.303-309
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• 2001

It is well known that the electrical impedance of biological tissues is very sensitive to their temperature. In this paper, we have analyzed the effects of temperature change on the phase of magnetic resonance images obtained with external current injection. It has been found that the local phase in the current injected magnetic resonance image can be changed noticeably when local temperature change appears at a part of the tissue. At the experiments with a 0.3 Tesla MRI system, we observed the local phase changes at the phantom images when the phantom temperature was varied between 25 -45$^{\circ}C$. We think that the current injection MRI technique can be used for in-vivo monitoring of the temperature inside biiological tissues if the relation between the local temperature and phase can be quantified.

• IEIE Transactions on Smart Processing and Computing
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• 제2권4호
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• pp.203-207
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• 2013

The appropriate handling of motion artifacts is essential for clinical diagnosis in magnetic resonance imaging (MRI). In many cases, motion is an inherent part of MR images because it is difficult to control during MR imaging. As the motion in the human body occur in a deformable manner, they are difficult to deal with. This paper proposes a novel detection method for periodically moving regions to produce MR images with less motion artifacts. When the data is acquired by the radial trajectory, the proposed method can extract the deformable region easily using the difference in the modulated sinograms, which have different periodic phase terms. The simulation results applied to the various cases confirmed the good performance of the proposed method.

• 스마트미디어저널
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• 제12권7호
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• pp.52-58
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• 2023

Alzheimer's disease is one type of dementia, the symptoms can be treated by detecting the disease at its early stages. Recently, many computer-aided diagnosis using magnetic resonance image(MRI) have shown a good results in the classification of AD. Taken these MRI images and feed to Free surfer software to extra the features. In consideration, using T1-weighted images and classifying using the convolution neural network (CNN) model are proposed. In this paper, taking the subjects from ADNI of subcortical and cortical features of 190 subjects. Consider the study to reduce the complexity of the model by using the single layer in the Res-Net, VGG, and Alex Net. Multi-class classification is used to classify four different stages, CN, EMCI, LMCI, AD. The following experiment shows for respective classification Res-Net, VGG, and Alex Net with the best accuracy with VGG at 96%, Res-Net, GoogLeNet and Alex Net at 91%, 93% and 89% respectively.

• Investigative Magnetic Resonance Imaging
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• 제16권1호
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• pp.55-66
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• 2012

목적 : 자기공명영상(MRI) 획득시 피험자의 머리 움직임은 영상의 품질에 영향을 줄 수 있다. 영상 왜곡의 발생 원인이 되는 피험자의 움직임을 감지하기 위한 3차원 광학 추적 시스템을 제작하였다. 대상 및 방법 : 시스템은 두 대의 CCD 카메라 및 적외선 조명, 구형 반사 마커, 프레임 그래버(frame grabber)와 데스크탑 컴퓨터로 구성되었다. 두 대의 카메라를 이용하여 마커의 움직임을 관측하는 스테레오 비전 시스템을 제작하고, 카메라의 내부/외부 매개변수를 측정하는 캘리브레이션(calibration)과 측정된 매개변수를 이용하여 3차원 움직임 정보를 계산하는 삼각측량(triangulation)기법을 적용하였다. 캘리브레이션 보드와 피험자용 안경을 제작하여 움직임 추적의 정확도와 실제 MRI 영상 촬영 동안의 움직임 검출의 유효성을 평가하였다. 결과 : 반사 마커가 부착된 안경을 쓴 피험자들이 MRI 영상 촬영 동안 머리를 규칙적으로 움직였을 때, 시스템은 MRI의 고자장 환경 내에서도 영상에 영향을 주지 않고 피험자들의 움직임을 잘 감지했다. 결론 : 제작한 스테레오 비전 시스템은피험자의 머리 움직임을 잘 감지하였고, 실시간 알림 기능을 통해 피험자의 움직임을 중지할 수 있도록 알려줌으로써 MRI 영상에 영향을 주는 것을 최소화할 수 있다.

• 대한의용생체공학회:의공학회지
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• 제41권1호
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• pp.28-34
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• 2020

In this paper, we introduce motion artifact reduction algorithm for interleaved MRI using an advanced 3D approximation algorithm. The motion artifact framework of this paper is data corrected by post-processing with a new 3-D approximation algorithm which uses data structure for each voxel. In this study, we simulate and evaluate our algorithm using Shepp-Logan phantom and T1-MRI template for both scattered dataset and uniform dataset. We generated motion artifact using random generated motion parameters for the interleaved MRI. In simulation, we use image coregistration by SPM12 (https://www.fil.ion.ucl.ac.uk/spm/) to estimate the motion parameters. The motion artifact correction is done with using full dataset with estimated motion parameters, as well as use only one half of the full data which is the case when the half volume is corrupted by severe movement. We evaluate using numerical metrics and visualize error images.

• 대한기관식도과학회지
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• 제2권2호
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• pp.194-199
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• 1996

Laser therapy is becoming an accepted procedure for tissue coagulation and ablation and is especially useful in treating tumors. The laser energy is applied to the tissue of interest through various delivery systems which are introduced percutaneously, via blood vessels, through body openings, or during surgical exposure of the tissue. One of the major obstacles to effective application of lasers has been the lack of reliable method to determine the extent of tissue involvement in real time. Several methods have been proposed for monitoring the tissue response and controlling the laser in real time during laser therapy. Among them, magnetic resonance imaging(MRI) has been introduced to monitor laser-tissue interactions because laser irradiation induces changes not only in the thermal motions of the hydrogen protons within the tissue but also in the distribution and mobility of water and lipids. The buttocks of New Zealand rabbits were treated by KTP and $CO_2$laser(power : 10 watts, exposure time:10 seconds). m images were taken at immediately after lasering, 1 week later, 2 weeks later, and at the same time, tissues were harvested for histopathologic study. We analyzed MR images and histopathologic findigs of laser-treated tissues. The MR images taken immediately after laser treatment showed 3 layer pattern and which was correlated with histopathologic changes. We suggest MRI may become a useful monitoring tools for laser-tissue interaction.