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Choi, Won Ho,Choi, Hye Ran,Seo, Eunsoo,Hwang, Jeewoo,Oh, Heekyung,Kim, Myeong Rae,Han, Su Rin,Kim, Min Seok,Kang, Seong-Hyeon,Lee, Youngjin Elsevier 2019 OPTIK -STUTTGART- Vol.183 No.-
<P><B>Abstract</B></P> <P>Magnetic resonance imaging (MRI) has many advantages and has developed various pulse sequences. In particular, the diffusion weighted image (DWI) technique is widely used because it can acquire images quickly during examination of stroke, through a proper adjustment of the diffusion-weighted gradient b-value. However, a setting with inappropriate b-value causes loss of image signal that increases the influence of noise. Therefore, in this study, we quantitatively evaluated image quality after applying a variety of algorithms to the image acquired by changing the b-value and the main magnetic field in the MRI device. To acquire the image, the phantom was self-produced with an acrylic panel and chicken breast. Wiener filter, total variation (TV), and our proposed fast non-local means (FNLM) noise reduction algorithms were applied to the image. Consequently, the signal intensity at a 3.0 T magnetic field increased by a factor 4.8 compared to a 1.5 T magnetic field. Moreover, the signal-to-noise ratio and contrast-to-noise ratio were highest with the FNLM algorithm, and the values increased by factors of 9.5 and 9.9 with a 1.5 T magnetic field and by factors of 9.9 and 5.0 with a 3.0 T magnetic field compared to the noise image, respectively. The result of time resolution, the Wiener filter appeared the finest value, but had no significant difference compared to FNLM algorithm. In conclusion, our results confirmed that the proposed FNLM noise reduction algorithm can acquire both improved image quality and high processing time in MRI imaging with the DWI technique.</P>
Choi, Hye Ran,Choi, Won Ho,Lee, Seung Chan,Ha, Yun Kyung,Kang, Seong Hyeon,Kim, Dae Ho,Lee, Youngjin WISSENSCHAFTLICHE VERLAGSGESELLSCHAFT MBH 2017 OPTIK -STUTTGART- Vol.143 No.-
<P><B>Abstract</B></P> <P>Nowadays, the interest and the number of examination of cerebral angiography and interventional procedure have been significantly increasing. In stent procedure on patients, the important point is to check especially whether the position of stent is complete. Also, the dilution ratio of contrast agent and normal saline (N/S) causes affect the quality of image. Thus, the purpose of this study was to find optimized dilution ratio of contrast agent for acquiring the high quality image with various diameters of self-production vessel model in AAPM head phantom. To evaluate the quality of image, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were used as a factor of quantitative measurement, and Likert scale was used as a factor of qualitative measurement. According to the results, we can acquire excellent result for 1:4 (contrast agent: N/S), 1:5, and 1:5 dilution ratios using 2, 3, and 5mm vessel diameters, respectively. In addition, quantitative measurement and qualitative measurement came up with same tendency. In conclusion, our results demonstrated that the 1:4 and 1:5 dilution ratio of contrast agent had outstanding results in 2, 3, and 5mm diameters of vessel model in phantom.</P>
Choi Min Joo,Choi Won Suk,Seong Hye,최준용,Kim Jong-Hyun,Kim Yae-Jean,Cho Eun Young,김동현,Park Hyesook,Lee Heeyoung,Kim Nam Joong,Song Joon Young,Cheong Hee Jin,Kim Sang Il,Peck Kyong Ran 대한의학회 2021 Journal of Korean medical science Vol.36 No.23
Background: This study presents a framework for determining the allocation and distribution of the limited amount of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods: After analyzing the pandemic strategies of the major organizations and countries and with a literature review conducted by a core panel, a modified Delphi survey was administered to 13 experts in the fields of vaccination, infectious disease, and public health in the Republic of Korea. The following topics were discussed: 1) identifying the objectives of the vaccination strategy, 2) identifying allocation criteria, and 3) establishing a step-by-step vaccination framework and prioritization strategy based on the allocation criteria. Two rounds of surveys were conducted for each topic, with a structured questionnaire provided via e-mail in the first round. After analyzing the responses, a meeting with the experts was held to obtain consensus on how to prioritize the population groups. Results: The first objective of the vaccination strategy was maintenance of the integrity of the healthcare system and critical infrastructure, followed by reduction of morbidity and mortality and reduction of community transmission. In the initial phase, older adult residents in care homes, high-risk health and social care workers, and personal support workers who work in direct contact with coronavirus disease 2019 (COVID-19) patients would be prioritized. Expansion of vaccine supply would allow immunization of older adults not included in phase 1, followed by healthcare workers not previously included and individuals with comorbidities. Further widespread vaccine supply would ensure availability to the extended adult age groups (50–64 years old), critical workers outside the health sector, residents who cannot socially distance, and, eventually, the remaining populations. Conclusion: This survey provides the much needed insight into the decision-making process for vaccine allocation at the national level. However, flexibility in adapting to strategies will be essential, as new information is constantly emerging.
Choi, Hye Ran,Kang, Seong-Hyeon,Lee, Seungwan,Han, Dong-Kyoon,Lee, Youngjin Elsevier 2018 OPTIK -STUTTGART- Vol.157 No.-
<P><B>Abstract</B></P> <P>In general, we used picture achieving and communicating system (PACS) for restoring X-ray images such as a converging optical disk. The data in restoring system is essential for efficient stored X-ray image control. To efficiently compress the X-ray images, joint photographic expert group (JPEG), JPEG 2000 and JPEG extended range (XR) were developed and widely used in diagnostic imaging field. Thus, the purpose of this study was to evaluate image performance using above-mentioned comparison methods with various phantoms based on digital X-ray imaging system. For that purpose, we acquired hand and chest phantom images with computed radiography (CR) using image plate (IP) and adjusted different compression rates. In addition, we used peak signal to noise ratio (PSNR) to compare image performance with three compression methods According to the results, when we used JPEG XR, 24% and 14% more efficient results than JPEG and JPEG 2000 were acquired in hand phantom images, respectively. Also, the PSNR results using JPEG XR were 9% and 12% better than that of JPEG and JPEG 2000 in chest phantom images, respectively. Based on our results, JPEG XR compression method is expected to be very useful in digital X-ray imaging system.</P>
Choi, Hoon-Seong,Lee, Mi-Ji,Choi, Sheu-Ran,Smeester, Branden A.,Beitz, Alvin J.,Lee, Jang-Hern Elsevier 2018 NEUROSCIENCE Vol.372 No.-
<P><B>Abstract</B></P> <P>Aromatase is a key enzyme responsible for the biosynthesis of estrogen from testosterone. Although recent evidence indicates that spinal cord aromatase participates in nociceptive processing, the mechanisms underlying its regulation and its involvement in nociception remain unclear. The present study focuses on the potential role of astrocyte aromatase in formalin-induced acute pain and begins to uncover one mechanism by which spinal aromatase activation is controlled. Following intraplantar formalin injection, nociceptive responses were quantified and immunohistochemistry/co-immunoprecipitation assays were used to investigate the changes in spinal Fos expression and the phospho-serine levels of spinal aromatase. Intrathecal (i.t.) injection of letrozole (an aromatase inhibitor) mitigated both the late phase formalin-induced nociceptive responses and formalin-induced spinal Fos expression. Furthermore, formalin-injected mice showed significantly reduced phospho-serine levels of aromatase, which is associated with the rapid activation of this enzyme. However, sigma-1 receptor inhibition with i.t. BD1047 blocked the dephosphorylation of aromatase and potentiated the pharmacological effect of letrozole on formalin-induced nociceptive responses. In addition, i.t. administration of a sub-effective dose of BD1047 potentiated the pharmacological effect of cyclosporin A (a calcineurin inhibitor) on both the formalin-induced reduction in phospho-serine levels of aromatase and nociceptive behavior. These results suggest that dephosphorylation is an important regulatory mechanism involved in the rapid activation of aromatase and that spinal sigma-1 receptors mediate this dephosphorylation of aromatase through an intrinsic calcineurin pathway.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dephosphorylated aromatase in astrocyte is involved in the process of formalin-induced acute nociception. </LI> <LI> Activation of astrocyte sigma-1 receptors is associated with the dephosphorylation of aromatase. </LI> <LI> Calcineurin signaling pathway is involved in the sigma-1 receptor-mediated dephosphorylation of aromatase. </LI> </UL> </P>