• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.102-107
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• 2007

In molecular imaging studies via magnetic resonance imaging, in vivo cell tracking is an important issue for the observation of cell therapy or disease behavior. High resolution imaging and longitudinal study are necessary to track the cell movement. Since the field inhomogeneity extends over several voxels, we have performed the numerical analysis using the sub-voxel method dividing a voxel of MR image into several elements and the information about the field inhomogeneity distribution around the micro-beads. We imbedded ferrite-composite micro-beads with the size of $20-150{\mu}m$ in the subject substituted for cells to induce local field distortion. In the phantom imaging with the isotropic voxel size of $200{\mu}m^3$, we could confirm the feasibility of sub-voxel tracking in a 3.0 T MRI.

• Imaging Science in Dentistry
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• 제50권3호
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• pp.199-208
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• 2020

Purpose: This study was performed to introduce an in vivo hybrid multimodality technique involving the coregistration of micro-computed tomography (micro-CT) and high-resolution magnetic resonance imaging (HR-MRI) to concomitantly visualize and quantify mineralization and vascularization at follow-up in a rat model. Materials and Methods: Three adult female rats were randomly assigned as test subjects, with 1 rat serving as a control subject. For 20 weeks, the test rats received a weekly intravenous injection of 30 ㎍/kg zoledronic acid, and the control rat was administered a similar dose of normal saline. Bilateral extraction of the lower first and second molars was performed after 10 weeks. All rats were scanned once every 4 weeks with both micro-CT and HR-MRI. Micro-CT and HR-MRI images were registered and fused in the same 3-dimensional region to quantify blood flow velocity and trabecular bone thickness at T0 (baseline), T4 (4 weeks), T8 (8 weeks), T12 (12 weeks), T16 (16 weeks), and T20 (20 weeks). Histological assessment was the gold standard with which the findings were compared. Results: The histomorphometric images at T20 aligned with the HR-MRI findings, with both test and control rats demonstrating reduced trabecular bone vasculature and blood vessel density. The micro-CT findings were also consistent with the histomorphometric changes, which revealed that the test rats had thicker trabecular bone and smaller marrow spaces than the control rat. Conclusion: The combination of micro-CT and HR-MRI may be considered a powerful non-invasive novel technique for the longitudinal quantification of localized mineralization and vascularization.

• 대한방사선기술학회지:방사선기술과학
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• 제42권2호
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• pp.113-117
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• 2019

The purpose of this study was to investigate the FA value which can produce the best T2-weighted images by measuring the signal intensity and noise according to the FA value change in the brain image and the abdominal image of the mouse using micro-MRI. Brain imaging and abdominal imaging of BALB / C mice weighing 20g were performed using 4.7T (Bruker BioSpin MRI GmbH) micro-MRI equipment, Turbo RARE-T2 (spin echo-T2) images were scanned at TR 3500 msec and TE 36 msec. The changes of the FA values were $60^{\circ}$, $80^{\circ}$, $100^{\circ}$, $120^{\circ}$, $140^{\circ}$, $160^{\circ}$ and $180^{\circ}$. We measured signal intensity according to FA values of ventricle and thalamus in brain imaging, The signal intensity of kidney and muscle around the kidney was measured in abdominal images. To obtain SNR and CNR, we measured the background signals of two different parts, not the tissue. In the brain (thalamus) image, the signal intensity of FA $100^{\circ}$ was 7,433 and SNR (6.49) was the highest. In the abdominal (kidney) image, the signal intensity was highest at 16,523 when FA was $120^{\circ}$, and the highest SNR was 8.54 when FA was $140^{\circ}$. The CNR value of the brain image was 1.38 at FA $60^{\circ}$ and gradually increased to 8.29 at FA $180^{\circ}$. The CNR value of the muscle adjacent to the kidney gradually increased from 2.36 when the FA value was $60^{\circ}$ and the highest value was 4,57 at the FA value $180^{\circ}$.

• Imaging Science in Dentistry
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• 제50권2호
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• pp.93-98
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• 2020

Purpose: Little is known regarding the accuracy of clinical magnetic resonance imaging (MRI) protocols with acceptable scan times in sinus graft assessment. The aim of this study was to evaluate the correlations between MRI and cone-beam computed tomographic (CBCT) measurements of maxillary sinus grafts using 2 different clinical MRI imaging protocols. Materials and Methods: A total of 15 patients who underwent unilateral sinus lift surgery with biphasic calcium phosphate were included in this study. CBCT, T1-weighted MRI, and T2-weighted MRI scans were taken 6 months after sinus lift surgery. Linear measurements of the maximum height and buccolingual width in coronal images, as well as the maximum anteroposterior depth in sagittal images, were performed by 2 trained observers using CBCT and MRI Digital Imaging and Communication in Medicine files. Micro-computed tomography (micro-CT) was also performed to confirm the presence of bone tissue in the grafted area. Correlations between MRI and CBCT measurements were assessed with the Pearson test. Results: Significant correlations between CBCT and MRI were found for sinus graft height (T1-weighted, r=0.711 and P<0.05; T2-weighted, r=0.713 and P<0.05), buccolingual width (T1-weighted, r=0.892 and P<0.05; T2-weighted, r=0.956 and P<0.05), and anteroposterior depth (T1-weighted, r=0.731 and P<0.05; T2-weighted, r=0.873 and P<0.05). The presence of bone tissue in the grafted areas was confirmed via micro-CT. Conclusion: Both MRI pulse sequences tested can be used for sinus graft measurements, as strong correlations with CBCT were found. However, correlations between T2-weighted MRI and CBCT were slightly higher than those between T1-weighted MRI and CBCT.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2009년도 Korea Superconductivity Society Meeting 2009
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• pp.65-65
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• 2009

• Journal of Korean Neurosurgical Society
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• 제63권4호
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• pp.463-469
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• 2020

Objective : This study aimed to investigate the changes and significance of microRNA155 levels in serum of patients with cerebral small vessel disease (CSVD). Methods : Thirty patients with CSVD who met the inclusion criteria were selected and divided into eight patients with lacunar infarction (LI) group and 22 patients with multiple lacunar infarction (MLI) combined with white matter lesions (WML) group according to the results of head magnetic resonance imaging (MRI). Thirty samples from healthy volunteers without abnormalities after head MRI examination were selected as the control group. The levels of serum microRNA155 in each group were determined by real-time polymerase chain reaction, and the correlation between microRNA155 in the serum of patients with CSVD and the increase of imaging lesions was analyzed by Spearman correlation analysis. Results : Compared with the control group, the serum microRNA155 level in the LI group, MLI combined with WML group increased, the difference was statistically significant (p<0.05); serum microRNA155 level was positively correlated with the increase of imaging lesions (p<0.05). Conclusion : The change of serum microRNA155 level in patients with CSVD may be one of its self-protection mechanisms, and the intensity of this self-protection mechanism is positively correlated with the number of CSVD lesions.

• 대한의용생체공학회:의공학회지
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• 제30권1호
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• pp.1-9
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• 2009

Many types of small animal imaging modalities, like micro-CT, micro-PET, and micro-SPECT, have been recently developed worldwide. Small animal imaging systems are now recognized as indispensable tools to validate efficacy and safety of new drugs or new therapeutic methods using the animal disease models. With increasing demands for small animal imaging in biomedical research, multimodal small animal imaging systems, like micro-PET/CT or micro PET/MRI, are now also being developed. Small animal imaging with spatial resolution and sensitivity comparable to human imaging is quite challenging since laboratory small animals are much smaller than human beings. Research activities in Korea on small animal imaging systems are reviewed in this paper. In the field of micro-CT and micro-PET, many world-class technologies have been developed successfully in Korea. It is expected that the developed animal imaging system technologies can be used in the development of clinical imaging systems in Korea in the near future.

• Investigative Magnetic Resonance Imaging
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• 제13권2호
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• pp.171-176
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• 2009

목적 : 자기공명영상 장비에서 신호를 주고 받는 주요 부분인 RF 코일의 성능 특성인 Q 값 (quality factor)과 신호대잡음비 (SNR, signal-to-noise ratio) 값에 미치는 코일 구리선 코팅 재질의 영향을 조사하고자 하였다. 대상 및 방법 : 폴리에스테르 (polyester), 폴리우레탄 (polyurethane), 폴리이미드 (polyimide), 폴리아마이드이미드 (polyamideimide), 폴리에스테르이미드 (polyester-imide)가 코팅된 직경 0.4 mm 구리선을 사용하여, 내경이 1.7mm인 RF 코일을 솔레노이드 형태로 제작한 후 network analyzer로 Q 값을 측정하였다. 또한 제작된 RF 코일을 600 MHz MRI (14.1 T, Bruker DMX600) 장비를 이용하여 표준시료를 이용한 자기공명영상 실험을 수행하였으며, 5개의 다른 코팅 재질과 코팅이 없는 경우에 대하여 영상에서의 신호대잡음비를 비교하였다. 결과 : 코팅 피복을 벗겨내고 측정한 신호대잡음비는 오차 범위에서 유사하였으며, 코팅되어 있는 경우에는 그 재질에 따라 Q 값 및 신호대잡음비가 다르고, 폴리에스테르의 경우를 제외하면 코팅 피복이 없는 경우와 비교하여 큰 값을 보였다. 폴리우레탄 코팅 구리선을 사용하였을 때 Q 값 및 신호대잡음비가 가장 크게 나타났으며, 가장 작은 값을 보인 폴리에스테르 코팅재질인 경우와 비교할 때 신호대잡음비가 34% 정도 큰 값을 보였다. 결론 : 1.2 mm 이하의 작은 생체시료에 적합한 솔레노이드형 RF 코일을 상용 프로브에 장착하여 사용할 수 있도록 손쉽게 제작하였으며, 폴리우레탄으로 코팅된 구리선으로 만들어진 코일의 경우 신호대잡음비가 30% 이상으로 가장 우수한 결과를 보였고, 따라서 코팅 재질의 선택이 자기공명영상의 결과에 중요하게 작용함을 확인할 수 있었다.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.83-86
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• 2003

Synchrotron X-ray micro imaging technique was employed to non-invasively monitor the water flow inside xylem vessels in a bamboo leaf. The phase contrast X-ray images clearly visualized plant anatomy and the rise of a water front inside the vessels. Consecutive X-ray images taken for 60 seconds revealed water rise kinetics against gravity in the xylem of a cut dry leaf taken from a bamboo tree. For the first time, traces of water rise, variation of contact angle between water and xylem wall as well as the internal structure of xylem were obtained. In xylem vessels, a repeating flow pattern has a typical flow velocity of $30.7{\mu}m/s$ and faster flow is established intermittently. It is concluded that the transmission type of X-ray micro imaging can be used as a powerful tool to investigate the ascent of sap in the xylem vessels at a resolution higher than that of MRI.

• Nuclear Medicine and Molecular Imaging
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• 제42권5호
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• pp.401-409
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• 2008

목적: 최근 들어, 분자 영상에서 다중 영상 기법이 널리 보급되고 있다. 우리는 PET/MR 융합 영상을 얻기 위해 쉽게 이용 가능한 점토와 순간 고형제를 이용하여 동물 특이적 자세 고정 틀을 제작하였다. 동물 특이적 자세 고정 틀은 동물의 고정과 재현성 있는 자세 연출이 가능하도록 한다. 여기에서 우리는 실험 동물의 틀을 제작하는데 있어 점토와 순간 고형제를 비교해 보았다. 재료 및 방법: MicroPET의 받침대와 잘 맞는 바닥이 둥근 아크릴 받침대를 먼저 제작하였다. 실험 동물은 마취 후, 자세 고정을 위해서 틀 위에 올려놓았다. 틀 제작을 위하여 순간 고형제와 점토가 사용되었다. 순간 고형제와 점토를 사용한 두 가지 경우 모두, 실험 동물의 자세 고정을 위하여 부드럽게 실험 동물을 눌러 위치를 잡았다. 위치가 잡혔으면, 쥐를 들어내고, 점토로 뜬 틀은 $60^{\circ}C$ 건조기에 넣어 두어 완전히 경화시켰다. 그리고 $[^{18}F]FDG$용액이 든 밀봉된 4개의 파이펫 팁을 기준 마커로 사용하였다. 실험 동물의 꼬리에 $[^{18}F]FDG$를 정맥 주사하여 microPET 스캔을 실시한 후, 동일한 실험동물을 순차적으로 MRI 스캔하였다. 결과: 다중 영상을 위하여 점토와 순간 고형제로 동물 특이적 자세 고정 틀을 제작하였다. MicroPET과 MRI를 통하여 기능적이고 해부학적인 영상을 얻었다. PET/MR 융합 영상은 무료로 이용 가능한 AMIDE 프로그램을 사용하여 획득할 수 있었다. 결론: 쉽게 이용 가능한 점토, 순간 고형제와 일회용 파이펫 팁을 사용하여 성공적으로 동물 특이적 자세 고정 틀을 제작할 수 있었다. 동물 특이적 자세 고정 틀 덕택으로, 적은 오차 범위 내에서 PET/MR 융합 영상을 얻을 수 있었다.