• 전자공학회논문지
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• 제52권12호
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• pp.134-141
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• 2015

본 연구의 목적은 1.0 mol 고농도 가돌리늄 조영제가 기존의 0.5 mol MR 조영제에 비해 얼마나 높은 신호강도를 보이는지를 정량적으로 비교 분석하는 것이다. 실험을 위하여 1.0 mol Gadobutrol과 0.5 mol Gadoteridol을 사용하여 희석비율을 달리한 각각의 MR팬텀을 제작하였다. 이를 1.5T MR장비의 조영증강 T1 검사인 2D SE 와 Head-Neck Angio의 3D FLASH 두 가지 방법으로 스캔하였다. 이후 영상에서 희석비율별 신호 강도를 측정하여 이를 비교 분석하였다. 두 개의 시퀀스(2D SE, 3D FLASH)에서의 조영증강 반응시작 지점인 RSP(Reaction Starting Point)는 0.5 mol에서는 두 시퀀스 각각 6.0%, 60.0%, 1.0mol에서는 2.0%, 20.0%로 0.5 mol 조영제서의 조영증강반응이 빨리 일어났다. 최대 신호강도인 MPSI(Max Peak Signal Intensity)는 0.5 mol에서 두 시퀀스 각각 1358.8[a.u], 1573.0[a.u], 1.0mol 에서는 1374.9[a.u], 1642.4[a.u]로 최대신호강도는 두 조영제 모두 비슷하였다. 더불어 최대신호강도를 보이는 희석비율 지점인 MPP(Max Peak Point)는 0.5 mol 에서는 두 시퀀스에서 각각 0.4%, 10.0%, 1.0mol 에서는 0.16%, 1,8%로 0.5 mol 조영제의 최대신호강도가 더 빨리 형성되었다. 각 희석비율에서의 조영증강 반응면적 RA(Reaction Area)는 0.5 mol 에서는 두 시퀀스 각각 20747.4[a.u], 23204.6[a.u], 1.0 mol 에서는 12691.9[a.u], 20747.4[a.u]로 0.5 mol 조영제가 두 시퀀스에서 각각 27.4%, 11.8% 더 높았다. 본 연구를 통하여 조영증강 T1과 Head-Neck Angio 검사에서 1.0 mol 고농도 가돌리늄 조영제가 0.5 mol MR조영제에 비하여 신호반응이 느리다는 사실을 확인하였으며, 최대 신호강도인 MPSI는 1.0 mol 조영제와 0.5 mol 조영제 둘 다 비슷하여 1.0 mol 고농도 가돌리늄 조영제가 MR영상에서 반드시 높은 신호강도를 보여주지 않는다는 것을 확인 할 수 있었다.

• Korean Journal of Radiology
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• 제22권9호
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• pp.1547-1554
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• 2021

Objective: We aimed to investigate whether repeated intravascular administration of iodinated contrast media (ICM) or gadolinium-based contrast agents (GBCAs) within a short interval was associated with an increased risk of post-contrast acute kidney injury (PC-AKI). Materials and Methods: This retrospective study included 300 patients (mean age ± standard deviation, 68.5 ± 8.1 years; 131 male and 169 female) who had undergone at least one ICM-enhanced perfusion brain CT scan, had their baseline and follow-up serum creatinine levels available, and had not undergone additional contrast-enhanced examinations 72 hours before and after a time window of interest were included. The study population was divided into three groups: single-dose group and groups of patients who had received multiple contrast administrations in the time window of interest with the minimum contrast repeat interval either within 4 hours (0-4-hour group) or between 4 to 48 hours (4-48-hour group). Multivariable logistic regression analysis was conducted to evaluate the association between AKI and repeated ICM administrations. A similar supplementary analysis was performed including both ICM and GBCA. Results: When ICM was only considered ignoring GBCA, among 300 patients, 207 patients received a single dose of ICM, 58 had repeated doses within 4 hours (0-4-hour group), and 35 patients had repeated doses between 4 to 48 hours (4-48-hour group). Most patients (> 95%) had a baseline estimated glomerular filtration rate (eGFR) of ≥ 30 mL/min/1.73 m². AKI occurred in 7.2%, 13.8%, and 8.6% of patients in the single-dose, 0-4-hour, and 4-48-hour groups, respectively. In the 0-4-hour and 4-48-hour groups, additional exposure to ICM was not associated with AKI after adjusting for comorbidities and nephrotoxic drugs (all p values > 0.05). Conclusion: Repeated intravascular administrations of ICM within a short interval did not increase the risk of AKI in our study patients suspected of acute stroke with a baseline eGFR of ≥ 30 mL/min/1.73 m².

• 한국군사과학기술학회지
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• 제23권3호
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• pp.213-220
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• 2020

This paper proposes a method on the performance analysis of pulse repetition frequency jitter compensation for generating Doppler profile. Exact phase compensation of each pulse is required to obtain Doppler profiles under pulse repetition frequency jitter. Three parameters such as velocity, pulse repetition frequency, and carrier frequency are examined to cause errors when conducting the pulse repetition frequency jitter compensation, then assuming well-focused Doppler profiles reflect well-conducted pulse repetition frequency jitter compensation, the proposed method in this paper utilizes the contrast to measure how well Doppler profile is generated. These are validated by electromagnetic computation data and computer simulation. Then, it is concluded which parameter is important on the performance analysis of pulse repetition frequency jitter compensation by using the contrast.

• Current Optics and Photonics
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• 제1권5호
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• pp.433-439
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• 2017

The rodent model has been used frequently to understand stroke pathophysiology, due to its low cost and the large spectrum of genetic strains available. Here, we present a diffuse speckle contrast analysis system (DSCA) with a $1{\times}2$ optical switch that was used to non-invasively assess cerebral blood flow (CBF) changes in the rat during intraluminal suturing for middle cerebral artery occlusion (MCAO) surgery. The blood flow index (BFI) in the left hemisphere was lower than that in the right hemisphere because the left middle cerebral artery was occluded. Furthermore, the performance of the DSCA system was compared with that of commercial laser Doppler flowmetry. The changes in the BFI measured by the two systems were correlated strongly. The DSCA system was less sensitive to motion artifacts and able to measure relatively deep tissue flow in the rat's brain. In conclusion, the DSCA system secured CBF monitoring during surgery in a rodent model without craniotomy.

• The Journal of Advanced Prosthodontics
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• 제8권3호
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• pp.181-186
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• 2016

PURPOSE. The opacity of zirconia is an esthetic disadvantage that hinders achieving natural and shade-matched restorations. The aim of this study was to evaluate the translucency of non-colored and colored framework zirconia and monolithic zirconia. MATERIALS AND METHODS. The three groups tested were: non-colored framework zirconia, colored framework zirconia with the A3 shade according to Vita Classic Scale, and monolithic zirconia (n=5). The specimens were fabricated in the dimensions of $15{\times}12{\times}0.5mm$. A spectrophotometer was used to measure the contrast ratio, which is indicative of translucency. Three measurements were made to obtain the contrast ratios of the materials over a white background ($L^*w$) and a black background ($L^*b$). The data were analyzed using the one-way analysis of variance and Tukey HSD tests. One specimen from each group was chosen for scanning electron microscope analysis. The determined areas of the SEM images were divided by the number of grains in order to calculate the mean grain size. RESULTS. Statistically significant differences were observed among all groups (P<.05). Non-colored zirconia had the highest translucency with a contrast ratio of 0.75, while monolithic zirconia had the lowest translucency with a contrast ratio of 0.8. The mean grain sizes of the non-colored, colored, and monolithic zirconia were 233, 256, and 361 nm, respectively. CONCLUSION. The translucency of the zirconia was affected by the coloring procedure and the grain size. Although monolithic zirconia may not be the best esthetic material for the anterior region, it may serve as an alternative in the posterior region for the bilayered zirconia restorations.

• 동의신경정신과학회지
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• 제16권1호
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• pp.185-192
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• 2005

Objectives : This study is for discovering the clinical Features of the sleep in ordinary symptoms based on the Sasang Constitution. The result of this study could be helpful to understand and to identify the patients as Soeumin in contrast with the other constitutions-Soyangin, Taeumin and Taeyangin. Methods : There were 1,229 patients(700 female), who answered the questionnaire about their ordinary sleeping patterns. They had been diagnosed, including their clinical Sasang Constitution, by the Sasang Constitution specialist at Bundang Oriental Hospital of Dongguk University. By applying the binary logistic regression analysis, we can measure the characteristics and the influence of ordinary sleeping patterns to the dependent variable(Sasang Constitution). Results : As a result of the binary logistic analysis on the observed questionnaire, we found the characteristics of the ordinary sleeping patterns on Soeumin in contrast the other constitutions. Firstly, Soeumin has a tendency that he wouldn't snore well in comparison with the others. Secondly, Soeumin has a tendency that he will dreams more, when he sleeps in contrast with the others. Thirthly, Soeumin has a tendency that he will sleep longer than 6-7hours. Fourthly, Soeumin has a tendency that he will struggle during sleeping in contrast with the others. Conclustion : This study will be used to identify patients as Soeumin in contrast with the others-Soyangin, Taeumin and Taeyangin.

• 한국전자통신학회논문지
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• 제14권4호
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• pp.707-714
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• 2019

최근 센서 네트워크 기술의 발달과 카메라 기술의 발달로 이 두 기술을 접목한 비쥬얼 센서 기술을 이용하여 사람이 접근하기 어려운 지역을 효과적으로 관찰 또는 감시하고자 하는 수요가 증가하고 있다. 비쥬얼 센서를 이용한 응용은 실외 지역을 카메라 센서를 이용하여 촬영하기 때문에 날씨나 시간에 따라 영상의 대비가 좋지 않은 영상이 얻어질 수 있다. 본 논문에서는 동일한 지역을 지속적으로 촬영하는 비쥬얼 센서의 특성을 이용하여 조도 대비 컬러 특성을 모델링하고 이 특성을 이용하여 대비가 개선된 영상을 실시간으로 만들 수 있는 방법을 제시한다. 제시하는 모델은 영상에서 관심영역을 설정하고 관심영역에 대해서 조도 대비 컬러 특성을 측정하여 이를 감마함수 형태로 모델링한다. 실험 결과는 제안하는 방법이 간단하면서도 정확하게 저대비 영상의 컬러 성분들을 보정하여 영상의 대비를 개선하는 것을 보여준다.

• Journal of Medicine and Life Science
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• 제16권1호
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• pp.1-5
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• 2019

Our purpose was to evaluate usefulness of the contrast-enhanced 3 dimensional fluid attenuated inversion recovery (3D-FLAIR) technique of half brain volume to diagnose the patients with facial neuritis based on segment-based analysis. We assessed retrospectively 17 consecutive patients who underwent brain MR imaging at 3 tesla for facial neuritis: 11 patients with idiopathic facial neuritis and 6 with herpes zoster oticus. Contrast enhanced 3D-FLAIR sequences of the half brain volume were analyzed and 3D T1-weighted sequence of the full brain volume were used as the base-line exam. Enhancement of the facial nerve was determined in each segment of 5 facial nerve segments by two radiologists. Sensitivity, specificity and accuracy of enhancement of each segment were assessed. The authors experienced a prompt fuzzy CSF enhancement in the fundus of the internal auditory canal in patients with enhancement of the canalicular segment. Interobserver agreement of CE 3D-FLAIR was excellent(${\kappa}$-value 0.885). Sensitivity, specificity, and accuracy of each segment are 1.0, 0.823, 0.912 in the canalicular segment; 0.118, 1.0, 0.559 in the labyrinthine segment; 0.823, 0.294, 0.559 in the anterior genu; 0.823, 0.529, 0.676 in the tympanic segment; 0.823, 0.235, 0.529 in the mastoid segment, respectively. In addition, those of prompt fuzzy enhancement were 0.647, 1.0, and 0.824, respectively. Incidence of prompt fuzzy enhancement with enhancement of the canalicular segment was 11 sites(55%): 6 (54.5%) in idiopathic facial neuritis and 5 (83.3%) in herpes zoster. Enhancement of the canalicular segment and prompt fuzzy enhancement on CE 3D-FLAIR was significantly correlated with occurrence of facial neuritis (p<0.001). CE 3D-FLAIR technique of the half brain volume is useful to evaluate the patients with facial neuritis as an adjunct sequence in addition to contrast-enhanced 3D T1-weighted sequence. On segment-based analysis, contrast enhancement of the canalicular segment is the most reliable. Prompt fuzzy enhancement is seen in not only herpes zoster, but in idiopathic facial neuritis.

• Journal of Korean Biological Nursing Science
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• 제6권2호
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• pp.57-68
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• 2004

The contrast medium is very commonly used in more than 90% of computed tomography(CT) scans. It is difficult to predict the occurrence of adverse reactions and the degree of adverse reactions are diverse from mild urticaria, itching, nausea, vomiting to even cardiopulmonary arrest. The purpose of this study was to evaluate the symptoms, occurrence rate and risk factors of the adverse reactions in patients after contrast injection during CT examinations. Two hundreds sixty-five patients showed symptoms of adverse reactions out of 71,117 adult patients who received intravenous contrast administration during CT scans from January 2003 to December 2003 at a general hospital. Data was collected by reviewing adverse reaction records and electronic medical record. The results of this study were as follows; 1. Adverse reactions occurred in 265 out of a total of 71,117 patients(0.37%). Clinical symptoms of adverse reactions were most commonly dermatologic problems such as urticaria(69.81%) and itching(63.02%), followed by dyspnea(14.34%), dizziness(11.70%), nausea(6.79%), and vomiting(7.17%). 2. Anaphylactoid reactions occurred in 47 out of a total of 265 patients, and their pattern of symptoms were most commonly related to cardiovascular system(90.91%), followed by respiratory system(82.22%), gastrointestinal system(51.72%), and dermatologic system(16.51%). Eleven patients were transferred to emergency room for further treatment and two patients needed cardiopulmonary resuscitation. 3. The adverse reactions were significantly more common in women than in men(0.46% vs.0.32%, p=.003) and in type D contrast medium than the others(p<.001). The occurrence rate of adverse reactions was not significantly different according to the age and infusion speed of the contrast medium.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.786-792
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• 2013

본 연구는 조영제 peak time에 영향을 주는 주된 생체 요인를 분석하여 검사에 적용함으로써 추가적인 조영제 주입에 따른 부작용을 최소화 하고 고해상도의 혈관영상을 유지하는 방안을 모색하고자 하였다. 시험적조영제주입법을 이용한 48명의 환자를 대상으로, 검사 전과 검사 중 환자의 생체 요인을 측정한 후, 조영제 peak time과 상관관계를 알아보고, 회귀식을 이용해 산출한 조영제 peak time이 측정된 조영제 peak time과 일치하는지 Bland-Altman plot를 통해 평가하였다. 연구결과, 검사 시 최저혈압과 심박동수가 조영제 peak time과 유의한 음의 상관관계를 보였고, 1단계 증가할 때마다 평균적으로 조영제 peak time은 -0.018과 -0.159로 유의하게 감소하였으며, 일치도가 상당히 높아 두 방법의 차이가 없음을 알 수 있다. 결론적으로 본 연구의 회귀식을 이용하면 우수한 화질을 유지하면서 환자에게 투여되는 조영제 사용량을 줄일 수 있어 기존의 방법을 대체할 수 있으리라 사료된다.