• Journal of Biosystems Engineering
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• v.24 no.6
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• pp.531-538
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• 1999

비파괴 품질 평가 기술인 핵 자기공명 분광법과 자기공명영상을 이용하여 소고기의 내부 구조를 분석하였다. 이완 상수 T$_1$과 T$_2$가 육류의 내부 구조와 관계가 있음을 보였다. 근육부분의 면적 비율이 증가할수록 T$_1$이 증가했다. 지방 부분의 T$_2$는 배 내부 부분의 T$_2$와 비슷한 값을 보였다. 자기공명 영상을 이용하여 육류의 원하는 부위의 T$_2$를 측정할 수 있는 방법을 구하였다. 근육 부분의 T$_2$가 길었으며 지방 부분의T$_2$가 짧았다. 부위별로 최적의 신호를 얻을 수 있는 자기공명영상 인자 TR과 TE를 구하였다. 자기공명영상을 이용하여 근육, 지방 그리고 뼈 성분에 따른 육류의 품질을 비파괴적으로 평가할 수 있는 가능성을 보여주었다.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.102-102
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• 2002

목적：$\Delta{R}_1$과 $\Delta{R}_2\;^{*}$은 $T_1$, $T_2\;^{*}$로부터 직접 구해야 하지만, 시간 해상도 때문에 각각 $T_1$, $T_2\;^{*}$ 강조영상으로부터 구하는 것이 일반적이다. $T_1$, $T_2\;^{*}$ 강조영상으로부터 얻은 $\Delta{R}_1$과 $\Delta{R}_2\;^{*}$ 과 이중 경사 자장에코 펄스열로부터 얻은 $\Delta{R}_1$과 $\Delta{R}_2\;^{*}$ 를 컴퓨터 가상 실험을 통해서 비교한다. 강조 영상의 신호 세기만으로는 정확한 관류 정보를 얻을 수 없음을 보이고자 한다. 대상 및 방법： 알려진 $\Delta{R}_1$과 $\Delta{R}_2\;^{*}$ 값을 이용하여 강조영상으로부터 구할 수 있는 $\DeltaR_1$과 $\Delta{R}_2\;^{*}$ 을 농도에 따라서 가상실험으로 구하고, 이 값과 이중 경사 자장 에코 펄스열로부터 구할 수 있는 $\Delta{R}_1$과 $\Delta{R}_2\;^{*}$를 가상실험으로 구해서 비교한다.

• Progress in Medical Physics
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• v.12 no.2
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• pp.113-124
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• 2001

For veterinary imaging diagnosis, we obtained MR images of the canine brain, spine, kidney and pelvis from 3T MRI system which was equipped with the world first 3T active shield magnet. Spin echo (SE) and fast Spin Echo (FSE) images were obtained from the canine brain, spine, kidney and pelvis of normal and sick dogs using a homemade birdcage and transverse electromagnetic (TEM) resonators operating in quadrature and tuned to 128 MHz. In addition, we employed a homemade saddle shaped RF coil. Typical common acquisition parameters were as follows: matrix=512$\times$512, field of view (FOV)=20cm, slice thickness=3 w, number of excitations (NEX)=1. For T1-weighted MR images, we used TR=500 ms, TE=10 or 17.4 ms. For T2-weighted MR images, we used TR=4000 ms, TE=108 ms. Signal to noise ratio (SNR) of 3T system was measured 2.7 times greater than that of prevalent 1.57 system. The high resolution images acquired in this study represent more than a 4-fold increase in in-plane resolution relative to conventional images obtained with a 20 cm field of view and a 5 mm slice thickness. MR images obtained from 3T system revealed numerous small venous structures throughout the image plane and provided reasonable delineation between gray and white matter The present results demonstrate that the MR images from 3T system could provide better diagnostic quality of resolution and sensitivity than those of 1.5T system. The elevated SNR observed in the 3T high field magnetic resonance imaging can be utilized to acquire images with a level of resolution approaching the microscopic structural level under in vivo conditions. These images represent a significant advance in our ability to examine small anatomical features with noninvasive imaging methods. Moreover, MRI technique could begin to apply for veterinary medicine in Korea.

• Journal of Veterinary Clinics
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• v.27 no.6
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• pp.755-759
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• 2010

A 6-year-old, intact female Dachshund was presented with generalized seizure for 2 days. Based on the neurologic and physical examinations, intracranial diseases were suspected. 1.5T and 7.0T magnetic resonance imaging (MRI) of the brain were taken. The MRI results revealed diffuse hyperintense lesions in the area of the diencephalon to the medulla oblongata in the T2-weighted images. Canine distemper virus-induced meningoencephalitis was confirmed by the result of RT-PCR of the cerebrospinal fluid (CSF). The dog was euthanized 7 days after diagnosis due to poor prognosis and clinical deterioration. Postmortem histopathologic examination was consistent with the MRI findings. This is the first case report using 1.5T and 7.0T MRI to compare the virus-induced intracranial lesions in meningoencephalitis.

• Journal of the Korean Society of Radiology
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• v.82 no.2
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• pp.429-434
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• 2021

Amyloidosis is a multisystemic disease characterized by the accumulation of abnormal proteins in extracellular spaces in various organs, with frequent involvement of the myocardium. We report a case of a patient who had cardiac amyloidosis with a trend of reduction in native T1 and T2 values and extracellular volume fraction on serial cardiac magnetic resonance imaging after chemotherapy and stem cell transplantation. The native T1 value and the extracellular volume fraction are closely associated with tissue amyloid burden in amyloidosis patients. This case demonstrated that cardiac magnetic resonance imaging may be used as a non-invasive and quantitative biomarker in the treatment monitoring of amyloidosis.

• Journal of radiological science and technology
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• v.32 no.2
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• pp.177-182
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• 2009

Purpose : This study presents the optimization of flip angle (FA) to obtain higher contrast to noise ratio (CNR) and lower specific absorption rate (SAR). Materials and Method : T1-weighted images of the cerebrum of brain were obtained from 50$^\circ$ to 130$^\circ$ FA with 10$^\circ$ interval. Signal to noise ratios (SNRs) were calculated for white matter (WM), gray matter (GM), and background noise. The proper FA was analyzed by T-test statistics and Kruskal-wallis analysis using R1 = 1- exp ($\frac{-TR}{T1}$) and Ernst angle cos $\theta$ = exp ($\frac{-TR}{T1}$). Results : The SNR of WM at 130$^\circ$ FA is approximately 1.6 times higher than the SNR of WM at 50$^\circ$. The SNR of GM at 130$^\circ$ FA is approximately 1.9 times higher than the SNR of GM at 50$^\circ$. Although the SNRs of WM and GM showed similar trends with the change of FA values, the slowdown point of decrease after linear fitting were different. While the SNR of WM started decreasing at 120$^\circ$ FA, the SNR of GM started decreasing at less than 110$^\circ$. The highest SNRs of WM and GM were obtained at 130$^\circ$ FA. The highest CNRs, however, were obtained at 80$^\circ$ FA. Conclusion : Although SNR increased with the change of FA values from 50$^\circ$ to 130$^\circ$ at 3T SE T1WI, CNR was higher at 80$^\circ$ FA than at the usually used 90$^\circ$ FA. In addition, the SAR was decreased by using smaller FA. The CNR can be increased by using this optimized FA at 3T MR SE T1WI.

• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.426-433
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• 2002

In this paper, we have studied the images which have been reconstructed by using combination of images acquired by the variation of operating frequency. When inner images have been reconstructed, they have been superposed by the surface state effect. In this case, the images of the phase object can be enhanced by the contrast of inner images. In this experiment, there are two kinds of specimens, one is a reference block haying 1/4T, 1/2T, 3/4T side drilled holes as main run piping material 111 the steam generator in NPP(Neuclear Power Plant)s and the another is a part of a hemisphere type specimen having about 1-2㎜ distance gap. It has been shown that the two results of defect shapes have better than before in this processing and phase contrast grow about twice. And we have constructed the acoustic microscope by using a quadrature detector that enables to acquire the amplitude and phase of the reflected signal simultaneously Further more ore have studied the reconstruction method of the amplitude and phase images and the enhancement method of the defect images contrast.

• The Journal of the Korea Contents Association
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• v.18 no.6
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• pp.461-466
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• 2018

In this study, we investigated the signal intensity changes by activating all and partially selected coil elements as a way to increase the SNR in a single region MR imaging. Two cylindrical fluid phantoms were placed side by side in a phase array coil and MRI scans were repeated by turning on the entire elements and selected elements. As a result, on both of the T1 and T2 weighted images signal intensities were significantly increased by 5.49% and 14.64%, respectively. In conclusion, if only a single region was to be imaged, selecting appropriate elements and collecting signals only from them could easily improve image qualities and signal intensities.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.137-137
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• 2002

목적： 동시획득 T1/T2 강조 경사자장 펄스열을 이용하여 근골격계의 종양 관류 평가를 하고자 한다. 대상 및 방법： 근골격계 양성 및 악성 종양을 대상으로 동시획득 T1/T2 강조 경사자장 펄스열을 이용하여 시간해상도를 1.2초로 하여 1000회(약20분)를 반복하여 역동적 영상을 얻는다. 각각의 TR/TE1/TE2는 10/2/8 msec이다. 각 시기에서 서로 다른 TE를 가지고 있는 두 개의 영상을 이용하여, 수학적으로 분리하여 T1과 T2 값을 얻고, 이를 시간에 따라 배열한다. 이를 통하여, T2의 경우에는 일차효과를 이용하여 조직관류량(tissue blood volume)을 측정하고, T1에서는 2구획모델을 이용하여 투과도(permeability)를 측정한다.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.34-42
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• 2014

Purpose : To evaluate the correlation of lesion-to-normal ratio (LNR) of signal intensity from double inversion recovery MR imaging and total choline-containing compound (tCho) resonance from single voxel MR spectroscopy in breast cancers. Materials and Methods: Between August 2008 and December 2009, 28 patients who were diagnosed as breast cancer and had undergone both double inversion recovery (DIR) MR imaging and MR spectroscopy (MRS) were included in this study. The signal intensities of the lesion (L) and ipsilateral normal breast tissue (N) were measured in region of interest of each breast cancer in DIR and contrast enhance MR image (CE-T1WI) to calculate the LNR value for each technique. MRS was performed using single-voxel MR spectroscopy. The height, width and area of tCho resonance were compared with each LNR of DIR and CE-T1WI. We used Pearson's correlation coefficient(r) for correlation analysis and the significance level was p=0.05. Results: There was no statistically significant correlation between LNR of CE-T1WI and height (r=-0.322, p=0.094), width (r=-0.233, p=0.232) and area (r=-0.309, p=0.109) of MRS tCho. There was no statistically significant correlation between LNR of DIR and height (r=0.067, p=0.735), width (r=-0.287, p=0.139) and area (r=0.012, p=0.953) of MRS tCho, either. The Pearson's correlation coefficient was 0.186 between LNRs of CET1WI and DIR (p=0.344). Conclusion: There was no statistically significant correlation between LNR of DIR and relative amount of tCho resonance of MRS.