• Title/Summary/Keyword: 혈류 지수

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Bilateral Popliteal Artery Entrapment Syndrome (양측성 슬와동맥 포착증후군)

  • Yoo, Dong-Gon;Kim, Chong-Wook;Park, Chong-Bin
    • Journal of Chest Surgery
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    • v.40 no.2 s.271
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    • pp.136-139
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    • 2007
  • Bilateral popliteal artery entrapment syndrome is a rare vascular disease, which leads to ischemic claudication as a result of disturbance to the blood flow from the abnormal relationship of the popliteal artery to the gastrocnemius muscle, a fibrous band or the popliteus muscle in the young male population. A 58-years-old male patient, complaining of ischemic claudication, coldness and 3rd toe gangrene of left leg of 1 month's duration was admitted to our institution. His left ankle-brachial index was decreased; therefore, a femoral artery angiography was peformed, which revealed a total occlusion below the distal superficial femoral artery of the left leg. An EKG revealed atrial fibrillation, suggestive of a thromboembolism of the popliteal artery due to atrial fibrillation; therefore, Urokinase thrombolysis was attempted. After the Urokinase thrombolysis, popliteal artery entrapment syndrome was diagnosed, with MRI then performed for an anatomical diagnosis. The popliteal artery entrapment was type 1, where the popliteal artery was displaced medial to the Gastrocnemius head. After complete removal of the popliteal artery aneurysm, interposition was performed with a contra lateral greater saphenous vein graft. A mild right popliteal artery aneurysm still remained, but surgery was not performed. Currently, the patent is surviving, without complications. Herein, the good results obtained for the surgical treatment of a severely affected leg, and the conservative treatment of a mildly affected leg, are reported.

Shear-wave elasticity imaging with axial sub-Nyquist sampling (축방향 서브 나이퀴스트 샘플링 기반의 횡탄성 영상 기법)

  • Woojin Oh;Heechul Yoon
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.5
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    • pp.403-411
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    • 2023
  • Functional ultrasound imaging, such as elasticity imaging and micro-blood flow Doppler imaging, enhances diagnostic capability by providing useful mechanical and functional information about tissues. However, the implementation of functional ultrasound imaging poses limitations such as the storage of vast amounts of data in Radio Frequency (RF) data acquisition and processing. In this paper, we propose a sub-Nyquist approach that reduces the amount of acquired axial samples for efficient shear-wave elasticity imaging. The proposed method acquires data at a sampling rate one-third lower than the conventional Nyquist sampling rate and tracks shear-wave signals through RF signals reconstructed using band-pass filtering-based interpolation. In this approach, the RF signal is assumed to have a fractional bandwidth of 67 %. To validate the approach, we reconstruct the shear-wave velocity images using shear-wave tracking data obtained by conventional and proposed approaches, and compare the group velocity, contrast-to-noise ratio, and structural similarity index measurement. We qualitatively and quantitatively demonstrate the potential of sub-Nyquist sampling-based shear-wave elasticity imaging, indicating that our approach could be practically useful in three-dimensional shear-wave elasticity imaging, where a massive amount of ultrasound data is required.

Diagnostic Imaging of Biliary Atresia (담도폐쇄증의 영상 진단)

  • Haesung Yoon;Hyun Ji Lim;Jisoo Kim;Mi-Jung Lee
    • Journal of the Korean Society of Radiology
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    • v.83 no.5
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    • pp.991-1002
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    • 2022
  • Biliary atresia is a rare but significant cause of neonatal cholestasis. An early and accurate diagnosis is important for proper management and prognosis. To diagnose biliary atresia, various imaging studies using ultrasonography, MRI, hepatobiliary scans, and cholangiography can be performed, although ultrasonography is more important for initial imaging studies. In this article, we review the findings of biliary atresia from various imaging modalities, including ultrasonography, MRI, hepatobiliary scans, and cholangiography. The known key imaging features include abnormal gallbladder size and shape, periportal thickening visible as a 'triangular cord' sign, invisible common bile duct, increased hepatic arterial flow, and combined anomalies. Aside from the imaging findings of biliary atresia, we also reviewed the diagnostic difficulty in the early neonatal period and the role of imaging in predicting hepatic fibrosis. We hope that this review will aid in the diagnosis of biliary atresia.

A Study on Industries's Leading at the Stock Market in Korea - Gradual Diffusion of Information and Cross-Asset Return Predictability- (산업의 주식시장 선행성에 관한 실증분석 - 자산간 수익률 예측 가능성 -)

  • Kim Jong-Kwon
    • Proceedings of the Safety Management and Science Conference
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    • 2004.11a
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    • pp.355-380
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    • 2004
  • I test the hypothesis that the gradual diffusion of information across asset markets leads to cross-asset return predictability in Korea. Using thirty-six industry portfolios and the broad market index as our test assets, I establish several key results. First, a number of industries such as semiconductor, electronics, metal, and petroleum lead the stock market by up to one month. In contrast, the market, which is widely followed, only leads a few industries. Importantly, an industry's ability to lead the market is correlated with its propensity to forecast various indicators of economic activity such as industrial production growth. Consistent with our hypothesis, these findings indicate that the market reacts with a delay to information in industry returns about its fundamentals because information diffuses only gradually across asset markets. Traditional theories of asset pricing assume that investors have unlimited information-processing capacity. However, this assumption does not hold for many traders, even the most sophisticated ones. Many economists recognize that investors are better characterized as being only boundedly rational(see Shiller(2000), Sims(2201)). Even from casual observation, few traders can pay attention to all sources of information much less understand their impact on the prices of assets that they trade. Indeed, a large literature in psychology documents the extent to which even attention is a precious cognitive resource(see, eg., Kahneman(1973), Nisbett and Ross(1980), Fiske and Taylor(1991)). A number of papers have explored the implications of limited information- processing capacity for asset prices. I will review this literature in Section II. For instance, Merton(1987) develops a static model of multiple stocks in which investors only have information about a limited number of stocks and only trade those that they have information about. Related models of limited market participation include brennan(1975) and Allen and Gale(1994). As a result, stocks that are less recognized by investors have a smaller investor base(neglected stocks) and trade at a greater discount because of limited risk sharing. More recently, Hong and Stein(1999) develop a dynamic model of a single asset in which information gradually diffuses across the investment public and investors are unable to perform the rational expectations trick of extracting information from prices. Hong and Stein(1999). My hypothesis is that the gradual diffusion of information across asset markets leads to cross-asset return predictability. This hypothesis relies on two key assumptions. The first is that valuable information that originates in one asset reaches investors in other markets only with a lag, i.e. news travels slowly across markets. The second assumption is that because of limited information-processing capacity, many (though not necessarily all) investors may not pay attention or be able to extract the information from the asset prices of markets that they do not participate in. These two assumptions taken together leads to cross-asset return predictability. My hypothesis would appear to be a very plausible one for a few reasons. To begin with, as pointed out by Merton(1987) and the subsequent literature on segmented markets and limited market participation, few investors trade all assets. Put another way, limited participation is a pervasive feature of financial markets. Indeed, even among equity money managers, there is specialization along industries such as sector or market timing funds. Some reasons for this limited market participation include tax, regulatory or liquidity constraints. More plausibly, investors have to specialize because they have their hands full trying to understand the markets that they do participate in

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Arginine Vasopressin Therapy of Vasodilatory Shock after Cardiac Surgery (심장 수술 후 혈관 확장성 쇼크가 발생한 환자에서 바소프레신 투여 요법)

  • Ahn, Young-Chan;Park, Chul-Hyun;Kim, Gun-Woo;Lee, Jae-Ik;Jun, Yang-Bin;Choi, Chang-Hyu;Hyun, Sung-Youl;Park, Kook-Yang
    • Journal of Chest Surgery
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    • v.39 no.12 s.269
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    • pp.913-919
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    • 2006
  • Background: Vasodilatory shock has been implicated in life-threatening complications after open heart surgery, where the systemic inflammatory reaction is attributed to the cardiopulmonary bypass(CPB). The secretion of arginine vasopressin(AVP) has been found to be defective in a variety of vasodilatory shock states and administration of AVP markedly improves vasomotor tone and blood pressure. So we reviewed our experience of AVP therapy in patients with vasodilatory shock following heart surgery using CPB. Material and Method: From January 2004 to July 2006, we reviewed the records of patients who received AVP therapy for vasodilatory shock following heart surgery using CPB. Vasodilatory shock was defined as a mean arterial pressure lower(MAP) than 70 mmHg, a cardiac index greater than 2.5 $L/min/m^2$, peripheral vascular resistance lower than 800 $dyn/s/cm^5$, and vasopressor requirements. The hemodynamic responses of patients who received AVP therapy for vasodilatory shock after cardiac surgery were analyzed retrospectively. Result: One hundred ninety nine open cardiac surgery patients were consecutively included in this study. Twenty two patients(11.1%) met criteria for vasodilatory shock. Despite the administration of high dose catecholamine vasopressor, all patients were hypotensive with a mean arterial pressure less than 70 mmHg. AVP therapy increased MAP from $53.3{\pm}7.4\;to\;82.0{\pm}12.0$ mmHg at 1 hour (p<0.001) and decreased other vasopressor requirements from $25{\pm}7\;to\;18{\pm}6$ at 1 hour(p<0.001) and individually maintained it for 12 hours. Conclusion: Our date suggest that AVP may be a safe and an effective vasopressor in patients with vasodilatory shock. In patients exhibiting vasodilatory shock after heart surgery, replacement of AVP increases blood pressure and reduces catecholamine vasopressor requirements.