RESULTS Through simulations of light hitting the side of a sphere and going through a lens, the agreement of this approach with analytical solutions is shown to be strong. CONCLUSIONS The MC method introduced here has the advantage of requiring only slight implementation changes from the current state-of-the-art to accurately simulate mismatched boundaries and readily exploit the acceleration of general-purpose graphics processing units. A code implementation, mcxyzn, is made available and maintained at https//omlc.org/software/mc/mcxyzn/.From December 2019, Coronavirus disease 2019 (COVID-19) pneumonia (formerly known as the 2019 novel Coronavirus [2019-nCoV]) broke out in Wuhan, China. In this study, we present serial CT findings in a 40-year-old female patient with COVID-19 pneumonia who presented with the symptoms of fever, chest tightness, and fatigue. She was diagnosed with COVID-19 infection confirmed by real-time reverse-transcriptase-polymerase chain reaction. CT showed rapidly progressing peripheral consolidations and ground-glass opacities in both lungs. After treatment, the lesions were shown to be almost absorbed leaving the fibrous lesions. Copyright © 2020 The Korean Society of Radiology.OBJECTIVE This study presents a preliminary report on the chest radiographic and computed tomography (CT) findings of the 2019 novel coronavirus disease (COVID-19) pneumonia in Korea. MATERIALS AND METHODS As part of a multi-institutional collaboration coordinated by the Korean Society of Thoracic Radiology, we collected nine patients with COVID-19 infections who had undergone chest radiography and CT scans. We analyzed the radiographic and CT findings of COVID-19 pneumonia at baseline. Fisher's exact test was used to compare CT findings depending on the shape of pulmonary lesions. RESULTS Three of the nine patients (33.3%) had parenchymal abnormalities detected by chest radiography, and most of the abnormalities were peripheral consolidations. Chest CT images showed bilateral involvement in eight of the nine patients, and a unilobar reversed halo sign in the other patient. In total, 77 pulmonary lesions were found, including patchy lesions (39%), large confluent lesions (13%), and small nodular lesions (48%). The peripheral and posterior lung fields were involved in 78% and 67% of the lesions, respectively. The lesions were typically ill-defined and were composed of mixed ground-glass opacities and consolidation or pure ground-glass opacities. Patchy to confluent lesions were primarily distributed in the lower lobes (p = 0.040) and along the pleura (p less then 0.001), whereas nodular lesions were primarily distributed along the bronchovascular bundles (p = 0.006). CONCLUSION COVID-19 pneumonia in Korea primarily manifested as pure to mixed ground-glass opacities with a patchy to confluent or nodular shape in the bilateral peripheral posterior lungs. A considerable proportion of patients with COVID-19 pneumonia had normal chest radiographs. Copyright © 2020 The Korean Society of Radiology.BACKGROUND AND OBJECTIVES Nationwide social inequalities of oral anticoagulation (OAC) usage after the introduction of non-vitamin K antagonist oral anticoagulants (NOACs) have not been well identified in patients with atrial fibrillation (AF). This study assessed overall rate and social inequalities of OAC usage after the introduction of NOAC in Korea. METHODS Between January 2002 and December 2016, we identified 888,540 patients with AF in the Korea National Health Insurance system database. The change of OAC rate in different medical systems after the introduction of NOAC were evaluated. RESULTS In all population, overall OAC use increased from 13.2% to 23.4% (p for trend less then 0.001), and NOAC use increased from 0% to 14.6% (p for trend less then 0.001). Compared with pre-reimbursement (0.48%), the annual increase of OAC use was significantly higher after partial (1.16%, p less then 0.001), and full reimbursement of OAC (3.72%, p less then 0.001). Full reimbursement of NOAC (adjusted odds ratio, 2.10; 95% confidence interval, 2.04-2.15) was independently associated with higher OAC use. However, the difference of overall OAC usage between tertiary referral hospitals and nursing or public health centers increased from 17.9% in 2010 to 36.8% in 2016. Moreover, usage rate of NOAC was significantly different among different medical systems from 37.2% at the tertiary referral hospital and 5.5% at nursing or public health centers. CONCLUSIONS Introduction of NOACs in routine practice for stroke prevention in AF was associated with improved rates of overall OAC use. However, significant practice-level variations in OAC and NOAC use remain producing social inequalities of OAC despite full reimbursement. BACKGROUND AND OBJECTIVES Although complete revascularization is known superior to incomplete revascularization in ST elevation myocardial infarction (STEMI) patients with multi-vessel coronary artery disease (MVCD), there are no definite instructions on the optimal timing of non-culprit lesions percutaneous coronary intervention (PCI). We compared 1-year clinical outcomes between 2 different complete multi-vessel revascularization strategies. METHODS From the Korea Acute Myocardial Infarction Registry-National Institute of Health, 606 patients with STEMI and MVCD who underwent complete revascularization were enrolled from November 2011 to December 2015. The patients were assigned to multi-vessel single-staged PCI (SS PCI) group (n=254) or multi-vessel multi-staged PCI (MS PCI) group (n=352).  https://www.selleckchem.com/products/c646.html  Propensity score matched 1-year clinical outcomes were compared between the groups. RESULTS At one year, MS PCI showed a significantly lower rate of all-cause mortality (hazard ratio [HR], 0.42; 95% confidential interval [CI], 0.19-0.92; p=0.030) compared with SS PCI. In subgroup analysis, all-cause mortality increased in SS PCI with cardiogenic shock (HR, 4.60; 95% CI, 1.54-13.77; p=0.006), age ≥65 years (HR, 4.00; 95% CI, 1.67-9.58, p=0.002), Killip class III/IV (HR, 7.32; 95% CI, 1.68-31.87; p=0.008), and creatinine clearance ≤60 mL/min (HR, 2.81; 95% CI, 1.10-7.18; p=0.031). After propensity score-matching, MS PCI showed a significantly lower risk of major adverse cardiovascular event than SS PCI. CONCLUSIONS SS PCI was associated with worse clinical outcomes compared with MS PCI. MS PCI for non-infarct-related artery could be a better option for patients with STEMI and MVCD, especially high-risk patients.