A highly sensitive magnetite nanoparticle as a simple and rapid stem cell labelling agent for MRI tracking

Kim, Hyunjin,Dae, Hyun-Mi,Park, Cheongsoo,Kim, Eun Ock,Kim, Daehong,Kim, In-Hoo,Kim, Yun-Hee,Choi, Yongdoo Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.21

<P>A superparamagnetic iron oxide nanoparticle (SPION) was coupled to 2-aminoethyl-trimethyl ammonium (TMA) in a 2-step ligand exchange reaction to produce TMA–SPION. This particle, which has a strong positive charge, was investigated as the basis for a simple and efficient method for labelling human mesenchymal stem cells (hMSCs) for noninvasive monitoring by magnetic resonance imaging (MRI). TMA–SPION has a <I>ζ</I> potential of +40 mV and a hydrodynamic size of 101 nm. In addition to its long-term stability in an aqueous solution, TMA–SPION has a low cytotoxicity and favourable magnetic properties as a <I>T</I><SUB>2</SUB> contrast agent due to its high relaxivity. The <I>T</I><SUB>2</SUB> relaxivity of TMA–SPION is 4.4 times greater than the commercially available Feridex® I.V. magnetic resonance agent. Despite a short labelling time of 4 h, hMSCs are efficiently labelled with TMA–SPION without the need for a transfection agent. An <I>in vivo</I> MRI study of a brain infarction model confirmed the utility of TMA–SPION as an MRI tracking marker of administered hMSCs.</P> <P>Graphic Abstract</P><P>Superparamagnetic magnetite nanoparticle with high r2 relaxivity (728.23 mM<SUP>-1</SUP> s<SUP>-1</SUP>) and zeta potential (+40 mV) was synthesized and evaluated <I>in vitro</I> and <I>in vivo</I>. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1jm10247h'> </P>

LAND , SAVING AND CAPITAL ACCUMULATION

KIM, WOO TACK,JAANG, DAEHONG,KIM, KYUNG SOO 한국국제경제학회 1993 International Economic Journal Vol.7 No.1

This paper critically reexamines the consequences of including land as a productive second asset in a neoclassical growth model under different savings behaviours. Both the dynamics and the equilibrium are shown to be altered significantly from those known previously in literature. [O41]

In vivo tracking of human mesenchymal stem cells in experimental stroke.

Kim, Daehong,Chun, Byoung-Gi,Kim, Yeon-Kyung,Lee, Yong Hyun,Park, Cheong-Soo,Jeon, Iksoo,Cheong, Chaejoon,Hwang, Tae-Sun,Chung, Hyungmin,Gwag, Byoung Joo,Hong, Kwan Soo,Song, Jihwan Pergamon Press ; Elsevier Science Ltd ; Elsevier S 2007 CELL TRANSPLANTATION Vol.16 No.10

<P>To understand the fates of human mesenchymal stem cells (hMSCs) following transplantation into a rodent model of middle cerebral artery occlusion (MCAo), magnetic resonance imaging (MRI) techniques were employed, hMSCs were labeled with ferumoxides (Feridex)--protamine sulfate complexes, which were visualized and examined by MRI up to 10 weeks following transplantation. Migration of the transplanted cells to the infarcted area was further confirmed by histological methods. We found that the hMSCs transplanted in MCAo models possess the capacity to migrate to the infarcted area extensively in both ipsilateral and contralateral injections, exhibiting a pathotropism. We also analyzed the detailed migration patterns of transplanted hMSCs. We speculate that the extensive migratory ability of hMSCs may represent a therapeutic potential for developing efficient cell transplantation strategies in stroke.</P>

Image Reconstruction of Sinogram Restoration using Inpainting method in Sparse View CT

Daehong Kim,Cheol-Ha Baek 한국방사선학회 2017 한국방사선학회 논문지 Vol.11 No.7

방사선 치료 전 환자 위치 확인을 위해 수행하는 콘빔 CT 촬영에서 환자 선량 감소를 위해 Sparse view CT가 사용되고 있다. 본 연구는 시뮬레이션과 실험을 통해 선형보간법과 inpainting 방법을 이용하여 사이 노그램의 sparse 데이터 복원하고 평가하는 것이다. 사이노그램 복원은 여러 간격의 각도로 획득된 영상에 적용되었다. 복원된 사이노그램은 역투영재구성법으로 재구성되었고, 그 결과를 평균제곱근오차와 영상의 프로파일로 나타내었다. 결과에 따르면, 평균제곱근오차와 영상 프로파일은 투영 각도와 복원법에 의존하 였다. 시뮬레이션과 실험 결과에서 inpainting 복원법은 선형보간법에 비해 사이노그램의 복원 측면에서 개 선된 결과를 보여주었다. 따라서, inpainting 방법은 환자 선량을 감소시키면서 영상화질을 유지시키는데 기 여할 수 있을 것이다. Sparse view CT has been widely used to reduce radiation dose to patient in radiation therapy. In this work, we performed sinogram restoration from sparse sampling data by using inpainting method for simulation and experiment. Sinogram restoration was performed in accordance with sampling angle and restoration method, and their results were validated with root mean square error (RMSE) and image profiles. Simulation and experiment are designed to fan beam scan for various projection angles. Sparse data in sinogram were restored by using linear interpolation and inpainting method. Then, the restored sinogram was reconstructed with filtered backprojection (FBP) algorithm. The results showed that RMSE and image profiles were depended on the projection angles and restoration method. Based on the simulation and experiment, we found that inpainting method could be improved for sinogram restoration in comparison to linear interpolation method for estimating RMSE and image profiles.

MR thermometry analysis program for laser- or high-intensity focused ultrasound (HIFU)-induced heating at a clinical MR scanner

Kim, Eun Ju,Jeong, Kiyoung,Oh, Seung Jae,Kim, Daehong,Park, Eun Hae,Lee, Young Han,Suh, Jin-Suck 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.

Feasibility of sinogram reconstruction based on inpainting method with decomposed sinusoid-like curve (S-curve) using total variation (TV) noise reduction algorithm in computed tomography (CT) imaging system: A simulation study

Kim, Daehong,Park, Sang Woong,Kim, Dae Ho,Yoo, Myung Seok,Lee, Youngjin Elsevier 2018 Optik Vol.161 No.-

<P><B>Abstract</B></P> <P>The use of computed tomography (CT) imaging system has increased significantly because it is very important role in the field of the medical diagnostic disease. However, CT has potential risk for high radiation dose and in addition to new strategy of reducing dose such as development of image reconstruction algorithm in sparse view conditions. Also, noise reduction is essential for improving image performance. In this study, with an aim to confirm feasibility of sinogram reconstruction based on inpainting method with decomposed sinusoid-like curve (S-curve) using total variation (TV) noise reduction algorithm in CT imaging system. For that purpose, we designed above-mentioned reconstruction and noise reduction algorithms and quantitatively evaluated coefficient of variation (COV), contrast to noise ratio (CNR) and root mean square error (RMSE). According to the results, our proposed image reconstruction method using TV noise reduction algorithm can acquire superb result in all evaluation parameters. The main benefit of our proposed method in sparse projection view is that it provides excellent image performance with efficient reconstruction in sinogram domain and noise reduction ratio. In conclusion, our results demonstrated that the better image performance using our proposed method can expect acquiring low scan time and low radiation dose.</P>

Image Reconstruction of Sinogram Restoration using Inpainting method in Spa se View CT

Daehong Kim(김대홍),Cheol-Ha Baek(백철하) 한국방사선학회 2017 한국방사선학회 논문지 Vol.11 No.7

방사선 치료 전 환자 위치 확인을 위해 수행하는 콘빔 CT 촬영에서 환자 선량 감소를 위해 Sparse view CT가 사용되고 있다. 본 연구는 시뮬레이션과 실험을 통해 선형보간법과 inpainting 방법을 이용하여 사이 노그램의 sparse 데이터 복원하고 평가하는 것이다. 사이노그램 복원은 여러 간격의 각도로 획득된 영상에 적용되었다. 복원된 사이노그램은 역투영재구성법으로 재구성되었고, 그 결과를 평균제곱근오차와 영상의 프로파일로 나타내었다. 결과에 따르면, 평균제곱근오차와 영상 프로파일은 투영 각도와 복원법에 의존하였다. 시뮬레이션과 실험 결과에서 inpainting 복원법은 선형보간법에 비해 사이노그램의 복원 측면에서 개선된 결과를 보여주었다. 따라서, inpainting 방법은 환자 선량을 감소시키면서 영상화질을 유지시키는데 기 여할 수 있을 것이다. Sparse view CT has been widely used to reduce radiation dose to patient in radiation therapy. In this work, we performed sinogram restoration from sparse sampling data by using inpainting method for simulation and experiment. Sinogram restoration was performed in accordance with sampling angle and restoration method, and their results were validated with root mean square error (RMSE) and image profiles. Simulation and experiment are designed to fan beam scan for various projection angles. Sparse data in sinogram were restored by using linear interpolation and inpainting method. Then, the restored sinogram was reconstructed with filtered backprojection (FBP) algorithm. The results showed that RMSE and image profiles were depended on the projection angles and restoration method. Based on the simulation and experiment, we found that inpainting method could be improved for sinogram restoration in comparison to linear interpolation method for estimating RMSE and image profiles.

Ion beam etching of sub-30nm scale Magnetic Tunnel Junction for minimizing sidewall leakage path

Daehong Kim,forBongho Kim,Sungwoo Chun,Jihun Kwon,Seonjun Choi,Seung-Beck Lee 한국자기학회 2011 한국자기학회 학술연구발표회 논문개요집 Vol.2011 No.12

Indirect Photon-counting Detector (PCD) for Transmission Imaging

Daehong Kim,Hakjae Lee,Seung-Jae Lee 한국자기학회 2020 Journal of Magnetics Vol.25 No.4

Photon-counting detectors (PCDs) are replacing energy integrating detectors in electromagnetic wave transmission imaging to achieve high performance. The purpose of this study was to develop an indirect PCD system for transmission imaging. The detector module is a combination of scintillator and SiPM, the SiPM is insensitive to magnetic field and operating at low voltage. A 2D array of a GAGG coupled with SiPM, positioning logic circuit, and preamplifier were enclosed in housing that sealed from light. A channel reduction circuit was used to identify the channel from the positioning logic circuit, and then output an analog pulse signal corresponding to the valid channel. The pulse signal measurements were performed using a oscilloscope. The profile analysis of the flood map confirmed that each point was distinct in both the center and peripheral regions. Additionally, the letters engraved on the phantom in the images were confirmed. Therefore, the indirect PCD system has potential for transmission imaging. Our future work will design an indirect PCD for low-energy photon detection and multi-energy imaging.

Evaluation of Ultra-low-dose (ULD) Lung Computed Tomography (CT) Using Deep-learning: A Phantom Study

Daehong Kim,Kihong Son,Cheol-Ha Baek,Pil-Hyun Jeon,Sooyeul Lee 한국자기학회 2021 Journal of Magnetics Vol.26 No.4

As an electromagnetic wave, X-rays are used to acquire diagnostic CT images. The aim of this phantom study was to evaluate the image quality of ultra-low-dose (ULD) lung computed tomography (CT) achieved using a deep-learning based image reconstruction method. The chest phantom was scanned with a tube voltage of 100 kV for various CT dose index (CTDIvol) conditions: 0.4 mGy for ultra-low-dose (ULD), 0.6 mGy for low-dose (LD), 2.7 mGy for standard (SD), and 7.1 mGy for large size (LS). The signal-to-noise ratio (SNR) and noise values in reconstructions produced via filtered back projection (FBP), iterative reconstruction (IR), and deep convolutional neural network (DCNN) were computed for comparison. The quantitative results of both the SNR and noise indicate that the adoption of the DCNN makes the image reconstruction in the ULD setting more stable and robust, achieving a higher image quality when compared with the FBP algorithm in the SD condition. Compared with the conventional FBP and IR, the proposed deep learning-based image reconstruction approach can improve the ULD CT image quality while significantly reducing the patient dose.