• Title/Summary/Keyword: MRA

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Diagnosis of Unruptured Intracranial Aneurysms Using Proton-Density Magnetic Resonance Angiography: A Comparison With High-Resolution Time-of-Flight Magnetic Resonance Angiography

  • Pae Sun Suh;Seung Chai Jung;Hye Hyeon Moon;Yun Hwa Roh;Yunsun Song;Minjae Kim;Jungbok Lee;Keum Mi Choi
    • Korean Journal of Radiology
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    • v.25 no.6
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    • pp.575-588
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    • 2024
  • Objective: Differentiating intracranial aneurysms from normal variants using CT angiography (CTA) or MR angiography (MRA) poses significant challenges. This study aimed to evaluate the efficacy of proton-density MRA (PD-MRA) compared to high-resolution time-of-flight MRA (HR-MRA) in diagnosing aneurysms among patients with indeterminate findings on conventional CTA or MRA. Materials and Methods: In this retrospective analysis, we included patients who underwent both PD-MRA and HR-MRA from August 2020 to July 2022 to assess lesions deemed indeterminate on prior conventional CTA or MRA examinations. Three experienced neuroradiologists independently reviewed the lesions using HR-MRA and PD-MRA with reconstructed voxel sizes of 0.253 mm3 or 0.23 mm3, respectively. A neurointerventionist established the gold standard with digital subtraction angiography. We compared the performance of HR-MRA, PD-MRA (0.253-mm3 voxel), and PD-MRA (0.23-mm3 voxel) in diagnosing aneurysms, both per lesion and per patient. The Fleiss kappa statistic was used to calculate inter-reader agreement. Results: The study involved 109 patients (average age 57.4 ± 11.0 years; male:female ratio, 11:98) with 141 indeterminate lesions. Of these, 78 lesions (55.3%) in 69 patients were confirmed as aneurysms by the reference standard. PD-MRA (0.253-mm3 voxel) exhibited significantly higher per-lesion diagnostic performance compared to HR-MRA across all three readers: sensitivity ranged from 87.2%-91.0% versus 66.7%-70.5%; specificity from 93.7%-96.8% versus 58.7%-68.3%; and accuracy from 90.8%-92.9% versus 63.8%-69.5% (P ≤ 0.003). Furthermore, PD-MRA (0.253-mm3 voxel) demonstrated significantly superior per-patient specificity and accuracy compared to HR-MRA across all evaluators (P ≤ 0.013). The diagnostic accuracy of PD-MRA (0.23-mm3 voxel) surpassed that of HR-MRA and was comparable to PD-MRA (0.253-mm3 voxel). The kappa values for inter-reader agreements were significantly higher in PD-MRA (0.820-0.938) than in HR-MRA (0.447-0.510). Conclusion: PD-MRA outperformed HR-MRA in diagnostic accuracy and demonstrated almost perfect inter-reader consistency in identifying intracranial aneurysms among patients with lesions initially indeterminate on CTA or MRA.

The Value of Comparison with Four Dimension Time Resolved Imaging of Contrast Kinetics(TRICKS) MRA by Time of Flight(TOF) MRA (4차원 TRICKS 자기공명혈관조영술과 기존 TOF 자기공명혈관조영술의 비교 및 유용성)

  • Bae, Sung-Jin;Lim, Cheong-Hwan;Park, Byung-Rae;Shin, Woon-Jae;Kim, Jung-Sam
    • The Journal of the Korea Contents Association
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    • v.10 no.3
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    • pp.215-221
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    • 2010
  • To assess the clinical value of time resolved imaging of contrast kinetics(TRICKS) MRA by comparison with conventional time of flight(TOF) MR angiography. Both TOF-MRA and TRICKS-MRA were performed in 17 patients with cerebrovascular disease and in 6 patients with brain tumor. Among 17 cerebraovascular patients, digital subtraction angiography(DSA) data were also obtained in 11 patients. TOF-MRA showed good spatial resolution but short in temporal resolution. Although TRICKS-MRA showed somewhat low spatial resolution, it showed superior temporal resolution by distinguishing vessel and tumor in all patients. Also, from the analysis of vessel-tumor relationship, TRICKS-MRA showed better performance than TOF-MRA. TRICKS-MRA makes it possible to image arterial, capillary and venous phase sequentially with very speedy manner and therefore, the clinical use of this method is highly suggestive for future use.

Four Dimension(4D) Time Resolved Imaging of Contrast Kinetics(TRICKS) MR Angiography (4차원 영상기법 Time Resolved Imaging of Contrast Kinetics MRA의 유용성)

  • Lim, cheong-hwan;Bae, sung-jin
    • Proceedings of the Korea Contents Association Conference
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    • 2009.05a
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    • pp.1105-1110
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    • 2009
  • To assess the clinical value of time resolved imaging of contrast kinetics(TRICKS) MRA by comparison with conventional time of flight(TOF) MR angiography. Both TOF-MRA and TRICKS-MRA were performed in 17 patients with cerebrovascular disease and in 6 patients with brain tumor. Among 17 cerebraovascular patients, digital subtraction angiography(DSA) data were also obtained in 11 patients. TOF-MRA showed good spatial resolution but short in temporal resolution. Although TRICKS-MRA showed somewhat low spatial resolution, it showed superior temporal resolution by distinguishing vessel and tumor in all patients. Also, from the analysis of vessel-tumor relationship, TRICKS-MRA showed better performance than TOF-MRA. TRICKS-MRA makes it possible to image arterial, capillary and venous phase sequentially with very speedy manner and therefore, the clinical use of this method is highly suggestive for future use.

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Effects of AEO-MRA on the Performance of Exporters and Importers in Korea

  • Kim, Chang-Bong;Chung, Il-Sok;Joo, Hye-Young
    • Journal of Korea Trade
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    • v.23 no.3
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    • pp.52-67
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    • 2019
  • Purpose - This study analyzes the effect of the authorized economic operator-mutual recognition arrangement (AEO-MRA) on the performance of Korean exporters and importers. The effect of the import-export companies' characteristics, such as annual sales, the number of foreign markets, and overseas experience, on the AEO-MRA is deduced; the relationship between this effect and firm performance is analyzed. Design/methodology - An empirical research model was constructed and analyzed using structural equation modeling. The effect of AEO-MRA on logistics and operational performance was derived from the aforementioned characteristics as leading factors of the AEO-MRA. The regulatory influence of cooperation with logistics companies was analyzed in the AEO-MRA effect on logistics performance. Thus, 172 valid samples were obtained from import-export companies certified by the AEO-MRA. Findings - Among the aforementioned characteristics, only "annual sales" has a positive effect on the AEO-MRA, whose effect enhances logistics and operational performances. The AEO-MRA effect did not directly affect operational performance. Owing to the adjustment effect analysis, the AEO-MRA effect and logistics performance relationship is strengthened if the cooperative relationship with the logistics company is higher than a certain level. If this cooperation falls below a certain level, the AEO-MRA effect on logistics performance reduces. Thus, logistics cooperation is an important factor in the AEO-MRA effect and logistics performance relationship. Originality/value - Hinging on the resource-based theory and relational viewpoint, an empirical model that explains the relationship between the AEO-MRA effect and firm performance is established.

Effects of Dietary Allium fistulosum L. and Tannic Acid on in vitro Ruminal Fermentation Characteristics and Methane Emission (국내산 파(Allium fistulosum L.)와 탄닌산을 이용한 사료첨가제가 in vitro 반추위 발효성상과 메탄 발생에 미치는 영향)

  • Lee, Shin-Ja;Eom, Jun-Sik;Kim, Hyun-Sang;Kim, Hyeong-Suk;Lee, Sung-Sill
    • Korean Journal of Organic Agriculture
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    • v.26 no.4
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    • pp.775-787
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    • 2018
  • This study was conducted to investigate for the natural methane emission inhibitor as a feed additive no adversely effect on rumen fermentation. Five different Control (Wheat barn (0.05 g), MRA(Methane Reduction Additive)-1 (Allium fistulosum L. (0.05 g)), MRA-2 (Sodium Lauryl Sulfate (0.025 g) + Wheat barn (0.025 g) mixed), MRA-3 (Sodium Dodecyl Sulfate (0.025 g) + Wheat barn (0.025 g) mixed), and MRA-4 (Allium fistulosum L. (0.02 g) + Tannic acid (0.02 g) + Wheat barn (0.01 g) mixed) contents were used to perform 3, 6, 9, 12, 24 and 48 h incubation for in vitro fermentation. Ruminal pH values were ranged within normal ruminal microbial fermentation. Dry matter digestibility was not significantly different across the treatments during the whole fermentation time. Also, the result of microbial growth had no adversely effect on during the whole fermentation time. At 24 h, methane emission was significantly lower (P<0.05) than all treatments except to MRA-1. Especially, MRA-4 carbon dioxide emission was significantly lower (P<0.05) than control at 9, 24 and 48 h incubation. In addition MRA-4 propionate concentration was significantly higher (P<0.05) than control at 24 h incubation. The result of RT-PCR Ciliate-associated methanogens were significantly lower (P<0.05) at MRA-1, MRA-3 and MRA-4 than control at 24 h incubation. Based on the present results, MRA-4 could be suggestible methane emission inhibitor as a natural feed additive.

A Study on the utilization plan of Mutual Recognition Agreement for Korea-China FTA: Focused on TBT and Conformity Assessment (한중 FTA체결에 따른 정부의 MRA 활용 방안에 관한 연구 -TBT 및 적합성평가를 중심으로-)

  • Jun, Byoung Ho;Kang, Byung Goo
    • International Commerce and Information Review
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    • v.17 no.3
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    • pp.177-201
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    • 2015
  • Korea-China FTA was initialized in 2015. Korea has a high level of dependence on trade for its economic growth, especially to China. Technical Barriers to Trade(TBT) among various non-tariff barriers is becoming increasingly important. Elimination of TBT is one of the key issues in which the South Korean government is interested since technical barriers significantly affect trade between the two countries. MRA has been considered as an effective tool to relieve such technical barriers. Several studies and surveys showed that MRA would mitigate the barriers of import and solve the problems that many companies face in international market. This study tries to seek utilization plan of MRA for Korea-China FTA. It suggests suitable utilization plan of MRA considering the difference of technical regulations between two countries. This paper has value in that it provides specific MRA strategies targeting China while other prior studies have merely analyzed the necessity of MRA.

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eMRA: Extension of MRA Considering the Relationships Between MDR Concepts (eMRA: MDR의 개념간 관계성을 고려한 MRA 확장)

  • Joo, Young-Min;Kim, Jangwon;Jeong, Dongwon;Baik, Doo-Kwon
    • KIPS Transactions on Software and Data Engineering
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    • v.2 no.3
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    • pp.161-172
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    • 2013
  • Metadata registry (MDR) is the international standard, developed by ISO/IEC for exchange and sharing data between databases. Many MDR systems are used in diverse domains such as medical service, bibliography, environment for sharing and integrating data. However, those systems have different physical structures individually because the MDR standard defines only the metamodel for registering and storing metadata. It causes heterogeneity between the system structures and requires additional cost to maintain interoperability. ISO/IEC 13249-8 Metadata Registry Access (MRA) is developing as an international standard to provide a consistent access facility to data stored in different metadata registries. However, MRA does not consider the relationships between the concepts (classes) defined in the MDR specification. It causes that incorrect query results returned from MDR systems. It also requires additional cost of modeling and rewriting queries to reflect each physical model. Therefore, this paper suggests eMRA which considers the relationships between the concepts in MDR. The comparative evaluations are described to show the advantages of eMRA. eMRA has superior performance in query modeling and referential integrity than MRA defined by the relationship between the concept of MDR.

The Implementation of Sub-MRA PWM Technique Using DSP (DSP를 이용한 Sub-MRA PWM 기법의 실현)

  • 이성백;이종규;원영진;한완옥;박진홍
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.8 no.2
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    • pp.41-45
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    • 1994
  • In this paper, it is implemented that Sub- MRA PWM techinque which is applied to MRA PWM technique using the Digital Signal Processor. Unstable element of analog is reduced for Sub - MRA PWM technique by digital signal pressing. And harmonic is analized by simulation to verify that. It is afford the process induction motor control with real time by minimizing the delay time of digital system. Time delay which is a defect of digital control can by minimized using fast caculation. Therefore, real time control is implemented in the induction motor

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The Effect of AEO MRA on Trade Cost (AEO MRA가 무역비용에 미치는 영향)

  • Eui-Hyun Ha
    • Korea Trade Review
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    • v.45 no.2
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    • pp.17-29
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    • 2020
  • This study analyzed that the effects of AEO MRA benefit on decreasing of trade cost and the strategies for expanding of trade. It uses the system GMM for effective solutions of endogenous matter with lagged dependent variable. In terms of the result of analysis, AEO MRA has a positive effect on decreasing of trade cost, especially this study proved the result of previous study AEO MRA expanded the trade through improving the time required for customs clearance and deregulation of non-tariff barriers. In conclusion, this study proposes the policy fo AEO MRA by analyzing the trade cost of AEO MRA by using the system GMM.

An Experimental Study on the Cause of Signal Inhomogeneity for Magnetic Resonance Angiography Using Phantom Model of Anterior Communicating(A-com) Artery (전교통동맥 모형을 이용한 자기공명혈관촬영술의 신호 불균일에 관한 실험적 연구)

  • Yoo, Beong-Gyu;Chung, Tae-Sub
    • Journal of radiological science and technology
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    • v.25 no.1
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    • pp.55-62
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    • 2002
  • Aneurysm-mimicking findings were frequently visualized due to hemodynamical causes of dephasing effects around area of A-com artery during magnetic resonance angiography(MRA) and these kind of phenomena have not been clearly known yet. We investigated the hemodynamical patterns of dephasing effect around area of the A-com artery that might be a cause of false intracranial aneurysms on MRA. For experimental study, We used hand-made silicon phantoms of the asymmetric A-com artery as like a bifurcation configuration. In a closed circulatory system with UHDC computer driven cardiac pump system. MRA and fast digital subfraction angiography(DSA) involved the use of these phantoms. Flow patterns were evaluated with axial and coronal imaging of MRA(2D-TOF, 3D-TOF) and DSA of Phantoms constructed from an automated closed-type circulatory system filled with glycerol solution [circulation fluid(glycerol:water = 1:1.4)]. These findings were then compared with those obtained from computational fluid dynamic(CFD) for inter-experimental correlation study. Imaging findings of MRA, DSA and CFD on inflow zone according to the following: a) MRA demonstrated high signal intensity zone as inflow zone on silicon phantom; b) Patterns of DSA were well matched with MRA on trajectory of inflow zone; and c) CFD were well matched with MRA on the pattern of main flow. Imaging findings of MRA. DSA and CFD on turbulent flow zone according to the following: a) MRA demonstrated hyposignal intensity zone at shoulder and axillar zone of main inflow; b) DSA delineated prominent vortex flow at the same area. The hemodynamical causes of signal defect, which could Induce the false aneurysm on MRA, turned out to be dephasing effects at axilla area of bifurcation from turbulent flow as the results of MRA, DSA and CFD.

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