• Investigative Magnetic Resonance Imaging
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• v.19 no.2
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• pp.67-75
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• 2015

Purpose: To investigate the value of image post-processing software (FreeSurfer, IBASPM [individual brain atlases using statistical parametric mapping software]) and inversion time (TI) in volumetric analyses of the hippocampus and to identify differences in comparison with manual tracing. Materials and Methods: Brain images from 12 normal adults were acquired using magnetization prepared rapid acquisition gradient echo (MPRAGE) with a slice thickness of 1.3 mm and TI of 800, 900, 1000, and 1100 ms. Hippocampal volumes were measured using FreeSurfer, IBASPM and manual tracing. Statistical differences were examined using correlation analyses accounting for spatial interpretations percent volume overlap and percent volume difference. Results: FreeSurfer revealed a maximum percent volume overlap and maximum percent volume difference at TI = 800 ms ($77.1{\pm}2.9%$) and TI = 1100 ms ($13.1{\pm}2.1%$), respectively. The respective values for IBASPM were TI = 1100 ms ($55.3{\pm}9.1%$) and TI = 800 ms ($43.1{\pm}10.7%$). FreeSurfer presented a higher correlation than IBASPM but it was not statistically significant. Conclusion: FreeSurfer performed better in volumetric determination than IBASPM. Given the subjective nature of manual tracing, automated image acquisition and analysis image is accurate and preferable.

• Korean Journal of Radiology
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• v.20 no.1
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• pp.126-133
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• 2019

Objective: To compare the lumbar vertebral bone marrow fat-signal fractions obtained from six-echo modified Dixon sequence (6-echo m-Dixon) with those from single-voxel magnetic resonance spectroscopy (MRS) in patients with low back pain. Materials and Methods: Vertebral bone marrow fat-signal fractions were quantified by 6-echo m-Dixon (repetition time [TR] = 7.2 ms, echo time (TE) = 1.21 ms, echo spacing = 1.1 ms, total imaging time = 50 seconds) and single-voxel MRS measurements in 25 targets (23 normal bone marrows, two focal lesions) from 24 patients. The point-resolved spectroscopy sequence was used for localized single-voxel MRS (TR = 3000 ms, TE = 35 ms, total scan time = 1 minute 42 seconds). A 2 × 2 × 1.5 cm³ voxel was placed within the normal L2 or L3 vertebral body, or other lesions including a compression fracture or metastasis. The bone marrow fat spectrum was characterized on the basis of the magnitude of measurable fat peaks and a priori knowledge of the chemical structure of triglycerides. The imaging-based fat-signal fraction results were then compared to the MRS-based results. Results: There was a strong correlation between m-Dixon and MRS-based fat-signal fractions (slope = 0.86, R² = 0.88, p < 0.001). In Bland-Altman analysis, 92.0% (23/25) of the data points were within the limits of agreement. Bland-Altman plots revealed a slight but systematic error in the m-Dixon based fat-signal fraction, which showed a prevailing overestimation of small fat-signal fractions (< 20%) and underestimation of high fat-signal fractions (> 20%). Conclusion: Given its excellent agreement with single-voxel-MRS, 6-echo m-Dixon can be used for visual and quantitative evaluation of vertebral bone marrow fat in daily practice.

• Molecules and Cells
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• v.39 no.12
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• pp.841-846
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• 2016

Local protein synthesis mediates precise spatio-temporal regulation of gene expression for neuronal functions such as long-term plasticity, axon guidance and regeneration. To reveal the underlying mechanisms of local translation, it is crucial to understand mRNA transport, localization and translation in live neurons. Among various techniques for mRNA analysis, fluorescence microscopy has been widely used as the most direct method to study localization of mRNA. Live-cell imaging of single RNA molecules is particularly advantageous to dissect the highly heterogeneous and dynamic nature of messenger ribonucleoprotein (mRNP) complexes in neurons. Here, we review recent advances in the study of mRNA localization and translation in live neurons using novel techniques for single-RNA imaging.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.109-109
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• 2001

Purpose： To assess the feasibility of sequential administration of ferumoxides and mangafodi trisodium in the same imaging protocols. Method： Thirty patients underwent double-contrast enhanced MR imaging of liver usi ferumoxides (Fe-MRI) and mangafodipir trisodium (Mn-MRI) on 1.5T GE Horizon system. In twenty patients, Mn-MRI was immediately followed by Fe-MRI. In ten patients, Fe-MR was performed first, then Mn-MRI was performed immediately, In all cases, precontras T1-weighted in-phase and opposed-phase spoiled gradient echo (GRE) images an T2-weighted fast spin-echo images (TR 4000ms, TE 102ms, ETL 8-12) were obtained Fe-MRI was performed with FSE and steady state GRE (TE 10 msec, flip angle 30 sequences. Mn-MRI was performed with in-phase and opposed-phase spoiled GR sequences. The SNR changes after the use of each contrast agents were calculated.

• Korean Journal of Digital Imaging in Medicine
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• v.6 no.1
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• pp.51-64
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• 2003

This thesis describes the effective interfacing methods of PACS Modality based on the system installation andoperating experiences. PACS(Picture Archiving and Communication Systems) is a system for medical image archiving and communication using large storage device and high-speed network. The standard communication protocol of PACS is DICOM(Digital Imaging and Communication in Medicine) based on TCP/IP and point-to-point protocol. However, there are many Non-DICOM Modalities and DICOM Modalities having problems. First, we had interfaced almost modalities. Fuji CR, GE CT, MRI, Angio, Fluoro, Phillips Angio, Shimadzu Fluoro. Ultrasound PACS, with the main PACS in the Seoul S Hospital as large scale hospital. And we manipulated the intelligent image distribution and the CT. MRI Interfaces never experienced beforein the Anyang J Hospital and the Chungju C Hospital as mid or small scale hospital. Technically, we developed both the DICOM Interface and the Non-DICOM Interface. At the last, the DICOM Worklist and the DICOM Print Interface were implemented in the Seoul B Hospital, the Bucheon SJ Hospital and the Seoul K Hospital independently with PACS. The Oracle, Sybase and MS-SQL are used as database, and UNIX, Macintosh, MS Windows as operating systems. And the Visual C++ and UNIX C are the main programming tools. We have used UTP, coaxial and fiber optic cable under 10/100 mbps LAN for networking.

• Korean Journal of Digital Imaging in Medicine
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• v.5 no.1
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• pp.46-63
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• 2002

This thesis describes the effective interfacing methods of PACS Modality based on the system installation and operating experiences. PACS(Picture Archiving and Communication Systems) is a system for medical image archiving and communication using large storage device and high-speed network. The standard communication protocol of PACS is DICOM(Digital Imaging and Communication in Medicine) based on TCP/IP and point-to-point protocol. However, there are many Non-DICOM Modalities and DICOM Modalities having problems. First, we had interfaced almost modalities, Fuji CR, GE CT, MRI, Angio, Fluoro, Phillips Angio, Shimadzu Fluoro, Ultrasound PACS, with the main PACS in the Seoul S Hospital as large scale hospital. And we manipulated the intelligent image distribution and the CT, MRI Interfaces never experienced before in the Anyang J Hospital and the Chungju C Hospital as mid or small scale hospital. Technically, we developed both the DICOM Interface and the Non-DICOM Interface. At the last, the DICOM Worklist and the DICOM Print Interface were implemented in the Seoul B Hospital, the Bucheon SJ Hospital and the Seoul K Hospital independently with PACS. The Oracle, Sybase and MS-SQL are used as database, and UNIX, Macintosh, MS Windows as operating systems. And the Visual C++ and UNIX C are the main programming tools. We have used UTP, coaxial and fiber optic Gable under 10/100 mbps LAN for networking.

• Progress in Medical Physics
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• v.24 no.4
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• pp.220-229
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• 2013

Respiratory-induced dynamic tumors render free-breathing cone-beam computed tomography (FBCBCT) images with motion artifacts complicating the task of quantifying the internal target volume (ITV). The purpose of this paper is to study the visibility of the revealed ITV when the imaging dose parameters, such as the kVp and mAs, are varied. The $Trilogy^{TM}$ linear accelerator with an On-Board Imaging ($OBI^{TM}$) system was used to acquire low-imaging-dose-mode (LIDM: 110 kVp, 20 mA, 20 ms/frame) and high-imaging-dose-mode (HIDM: 125 kVp, 80 mA, 25 ms/frame) FBCBCT images of a 3-cm diameter sphere (density=0.855 $g/cm^3$) moving in accordance to various sinusoidal breathing patterns, each with an unique inhalation-to-exhalation (I/E) ratio, amplitude, and period. In terms of image ITV contrast, there was a small overall average change of the ITV contrast when going from HIDM to LIDM of $6.5{\pm}5.1%$ for all breathing patterns. As for the ITV visible volume measurements, there was an insignificant difference between the ITV of both the LIDM- and HIDM-FBCBCT images with an average difference of $0.5{\pm}0.5%$, for all cases, despite the large difference in the imaging dose (approximately five-fold difference of ~0.8 and 4 cGy/scan). That indicates that the ITV visibility is not very sensitive to changes in imaging dose. However, both of the FBCBCT consistently underestimated the true ITV dimensions by up to 34.8% irrespective of the imaging dose mode due to significant motion artifacts, and thus, this imaging technique is not adequate to accurately visualize the ITV for image guidance. Due to the insignificant impact of imaging dose on ITV visibility, a plausible, alternative strategy would be to acquire more X-ray projections at the LIDM setting to allow 4DCBCT imaging to better define the ITV, and at the same time, maintain a reasonable imaging dose, i.e., comparable to a single HIDM-FBCBCT scan.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.230.1-230.1
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• 2015

One of the major problems of biological ToF-SIMS imaging is the lack of protein and peptide imaging. Most of biological story telling is mianly based on proteins. The biological implication of lipid ToF-SIMS imaging would be much higher if protein imaging is provided together. Utilizing high secondary ion yields of metals, proteins can be ToF-SIMS imaged with nanoparticle tagged proteins. Nanoparticles such as Fe3O4, SiO2, PbS were used for imaing NeuN, MCH, Orexin A, ${\alpha}$ synucline, TH(Tryosine Hydroxylase) in mouse tissues with a spatial resolution of ${\sim}2{\mu}m$ using a TOF-SIMS. Lipids and neurotransmitters images obtained simultaneously with protein images were overlayed for more deeper understanding of neurobiology, which is not allowed by any other bioimaging technqiues. The protein images from TOF-SIMS were compared with confocal fluorescence microscopy and NanoSIMS images. A new sample preparation method for imaging single cell membranes in a tissue using the vibrotome technique to prepare a tissue slice without any fixation and freeze drying will be also presented briefly for Hippocampus and Hypothalamus tissues.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3178-3180
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• 1999

초음파 진단기의 신호처리에 필요한 8-b 해상도와 40MS/s 이상의 변환속도를 갖는 ADC를 Folding and Interpolating 형태로 설계했다. 전력소모와 입력단의 오프셋에 의한 영향을 줄이기 위해 프리엠프의 출력을 Interpolation하여 그 개수를 절반으로 줄임으로써 전력소모를 줄였고, 기존의 전압모드 Interpolation 회로에서의 단순한 source follower를 정궤환을 이용한 버퍼의 형태로 바꾸어 이득을 개선시킴으로써 전압의 이용율을 높일 수 있었다. ADC에서 가장 중요한 비교기를 설계함에 있어서는 다이나믹 전력 소모만 있는 구조에 킥-백 노이즈를 줄이기 위한 설계를 했다 $0.6{\mu}m$ CMOS 공정을 이용해 설계되었고, Layout 결과 칩의 면적은 $1.3mm{\times}1.3mm$. 모의 실험결과 40MS/s에서 70mw의 전력을 소모하였다.

• Investigative Magnetic Resonance Imaging
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• v.24 no.3
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• pp.141-153
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• 2020

Purpose: Myocardial T1 and T2 relaxation times are affected by technical factors such as cardiovascular magnetic resonance platform/vendor. We aimed to validate T1 and T2 mapping sequences using a phantom; establish reference T1, T2, and extracellular volume (ECV) measurements using two sequences at 3T in normal Koreans; and compare the protocols and evaluate the differences from previously reported measurements. Materials and Methods: Eleven healthy subjects underwent cardiac magnetic resonance imaging (MRI) using 3T MRI equipment (Verio, Siemens, Erlangen, Germany). We did phantom validation before volunteer scanning: T1 mapping with modified look locker inversion recovery (MOLLI) with 5(3)3 and 4(1)3(1)2 sequences, and T2 mapping with gradient echo (GRE) and TrueFISP sequences. We did T1 and T2 mappings on the volunteers with the same sequences. ECV was also calculated with both sequences after gadolinium enhancement. Results: The phantom study showed no significant differences from the gold standard T1 and T2 values in either sequence. Pre-contrast T1 relaxation times of the 4(1)3(1)2 protocol was 1142.27 ± 36.64 ms and of the 5(3)3 was 1266.03 ± 32.86 ms on the volunteer study. T2 relaxation times of GRE were 40.09 ± 2.45 ms and T2 relaxation times of TrueFISP were 38.20 ± 1.64 ms in each. ECV calculation was 24.42% ± 2.41% and 26.11% ± 2.39% in the 4(1)3(1)2 and 5(3)3 protocols, respectively, and showed no differences at any segment or slice between the sequences. We also calculated ECV from the pre-enhancement T1 relaxation time of MOLLI 5(3)3 and the post-enhancement T1 relaxation time of MOLLI 4(1)3(1)2, with no significant differences between the combinations. Conclusion: Using phantom-validated sequences, we reported the normal myocardial T1, T2, and ECV reference values of healthy Koreans at 3T. There were no statistically significant differences between the sequences, although it has limited statistical value due to the small number of subjects studied. ECV showed no significant differences between calculations based on various pre- and post-mapping combinations.