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RISS 인기검색어
- 검색키워드
- 저자 : Quan Xu (검색결과 148 건)
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Xiao-Quan Xu,Hao Hu,Guo-Yi Su,Hu Liu,Hai-Bin Shi,Fei-Yun Wu 대한영상의학회 2016 Korean Journal of Radiology Vol.17 No.5
Objective: To evaluate the differences in the apparent diffusion coefficient (ADC) measurements based on three different region of interest (ROI) selection methods, and compare their diagnostic performance in differentiating benign from malignant orbital tumors. Materials and Methods: Diffusion-weighted imaging data of sixty-four patients with orbital tumors (33 benign and 31 malignant) were retrospectively analyzed. Two readers independently measured the ADC values using three different ROIs selection methods including whole-tumor (WT), single-slice (SS), and reader-defined small sample (RDSS). The differences of ADC values (ADC-ROIWT, ADC-ROISS, and ADC-ROIRDSS) between benign and malignant group were compared using unpaired t test. Receiver operating characteristic curve was used to determine and compare their diagnostic ability. The ADC measurement time was compared using ANOVA analysis and the measurement reproducibility was assessed using Bland-Altman method and intra-class correlation coefficient (ICC). Results: Malignant group showed significantly lower ADC-ROIWT, ADC-ROISS, and ADC-ROIRDSS than benign group (all p < 0.05). The areas under the curve showed no significant difference when using ADC-ROIWT, ADC-ROISS, and ADC-ROIRDSS as differentiating index, respectively (all p > 0.05). The ROISS and ROIRDSS required comparable measurement time (p > 0.05), while significantly shorter than ROIWT (p < 0.05). The ROISS showed the best reproducibility (mean difference ± limits of agreement between two readers were 0.022 [-0.080–0.123] x 10-3 mm2/s; ICC, 0.997) among three ROI methods. Conclusion: Apparent diffusion coefficient values based on the three different ROI selection methods can help to differentiate benign from malignant orbital tumors. The results of measurement time, reproducibility and diagnostic ability suggest that the ROISS method are potentially useful for clinical practice.
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Xiao-Quan Xu,Sheng Liu,Qing-Quan Zu,Lin-Bo Zhao,Jin-Guo Xia,Chun-Gao Zhou,Wei-Zhong Zhou,Hai-Bin Shi 대한신경과학회 2013 Journal of Clinical Neurology Vol.9 No.2
Background and Purpose This study evaluated the clinical value of detachable-balloon embolization for traumatic carotid-cavernous fistula (TCCF), focusing on the frequency, risk factors, and retreatment of recurrence. Methods Fifty-eight patients with TCCF underwent transarterial detachable-balloon embolization between October 2004 and March 2011. The clinical follow-up was performed every 3months until up to 3 years postprocedure. Each patient was placed in either the recurrence group or the nonrecurrence group according to whether a recurrence developed after the first procedure. The relevant factors including gender, fistula location, interval between trauma and the interventional procedure, blood flow in the carotid-cavernous fistula, number of balloons, and whether the internal carotid artery (ICA) was sacrificed were evaluated. Results All 58 TCCFs were successfully treated with transarterial balloon embolization, including 7 patients with ICA sacrifice. Recurrent fistulas occurred in seven patients during the follow-up period. Univariate analysis indicated that the interval between trauma and the interventional procedure (p=0.006) might be the main factor related to the recurrence of TCCF. The second treatments involved ICA sacrifice in two patients, fistula embolization with balloons in four patients, and placement of a covered stent in one patient. Conclusions Detachable balloons can still serve as the first-line treatment for TCCFs and recurrent TCCFs despite having a nonnegligible recurrence rate. Shortening the interval between trauma and the interventional procedure may reduce the risk of recurrence.
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Xiao-Quan Xu,Chen-Jiang Wu,Shan-Shan Lu,Qian-Qian Gao,Qing-Quan Zu,Xing-Long Liu,Hai-Bin Shi,Sheng Liu 대한영상의학회 2017 Korean Journal of Radiology Vol.18 No.5
Objective: To determine the relationship between intravoxel incoherent motion (IVIM) imaging derived quantitative metrics and serum soluble CD40 ligand (sCD40L) level in an embolic canine stroke model. Materials and Methods: A middle cerebral artery occlusion model was established in 24 beagle dogs. Experimental dogs were divided into low- and high-sCD40L group according to serum sCD40L level at 4.5 hours after establishing the model. IVIM imaging was scanned at 4.5 hours after model establishment using 10 b values ranging from 0 to 900 s/mm2. Quantitative metrics diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) of ischemic lesions were calculated. Quantitative metrics of ischemic lesions were normalized by contralateral hemisphere using the following formula: normalized D = Dstroke / Dcontralateral. Differences in IVIM metrics between the low- and high-sCD40L groups were compared using t test. Pearson’s correlation analyses were performed to determine the relationship between IVIM metrics and serum sCD40L level. Results: The high-sCD40L group showed significantly lower f and normalized f values than the low-sCD40L group (f, p < 0.001; normalized f, p < 0.001). There was no significant difference in D*, normalized D*, D, or normalized D value between the two groups (All p > 0.05). Both f and normalized f values were negatively correlated with serum sCD40L level (f, r = -0.789, p < 0.001; normalized f, r = -0.823, p < 0.001). However, serum sCD40L level had no significant correlation with D*, normalized D*, D, or normalized D (All p > 0.05). Conclusion: The f value derived from IVIM imaging was negatively correlated with serum sCD40L level. f value might serve as a potential imaging biomarker to assess the formation of microvascular thrombosis in hyperacute period of ischemic stroke.
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Xiao Quan Xu,최영준,성유섭,윤라경,장승원,박지은,허영진,백정환,이정현 대한영상의학회 2016 Korean Journal of Radiology Vol.17 No.5
Objective: To investigate the correlation between perfusion- and diffusion-related parameters from intravoxel incoherent motion (IVIM) and those from dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted imaging in tumors and normal muscles of the head and neck. Materials and Methods: We retrospectively enrolled 20 consecutive patients with head and neck tumors with MR imaging performed using a 3T MR scanner. Tissue diffusivity (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) were derived from bi-exponential fitting of IVIM data obtained with 14 different b-values in three orthogonal directions. We investigated the correlation between D, f, and D* and model-free parameters from the DCE-MRI (wash-in, Tmax, Emax, initial AUC60, whole AUC) and the apparent diffusion coefficient (ADC) value in the tumor and normal masseter muscle using a whole volume-of-interest approach. Pearson’s correlation test was used for statistical analysis. Results: No correlation was found between f or D* and any of the parameters from the DCE-MRI in all patients or in patients with squamous cell carcinoma (p > 0.05). The ADC was significantly correlated with D values in the tumors (p < 0.001, r = 0.980) and muscles (p = 0.013, r = 0.542), despite its significantly higher value than D. The difference between ADC and D showed significant correlation with f values in the tumors (p = 0.017, r = 0.528) and muscles (p = 0.003, r = 0.630), but no correlation with D* (p > 0.05, respectively). Conclusion: Intravoxel incoherent motion shows no significant correlation with model-free perfusion parameters derived from the DCE-MRI but is feasible for the analysis of diffusivity in both tumors and normal muscles of the head and neck.
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徐泉(XU QUAN),??洪(CHEN YING HONG) 동아대학교 법학연구소 2017 國際去來와 法 Vol.- No.18
TPP Financial Services Chapter makes clear regulations on Market Access for Financial Institutions, Cross-Border Trade, Investment Disputes in Financial Services, etc. And innovations are made in the terms of new financial service, self-regulatory organization, consultations and so on. TPP Financial Services Chapter is mainly based on the United States and other developed countries. Set by the developed countries’ market environment and financial conditions, the terms of TPP Financial Services are not beneficial to developing countries including China. Many rules of TPP Financial Services Chapter are quite inadaptable to Chinas existing financial legal systems. However, in the light of the foresight of TPP Financial Services Chapter and the importance of the financial sector for sovereign states, we should treat TPP Financial Services Chapter dialectically. On the one hand, China could take reference from it to improve the financial legal system in China. On the other hand, China should participate in the cooperation of international financial services and financial policy coordination, striving for the right to speak in the field of International Finance.
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Tetravalent half-arc-transitive graphs of order <sup>p4</sup>
Feng, Yan-Quan,Kwak, Jin Ho,Xu, Ming-Yao,Zhou, Jin-Xin Elsevier 2008 European journal of combinatorics : Journal europ& Vol.29 No.3
<P><B>Abstract</B></P><P>A graph is half-arc-transitive if its automorphism group acts transitively on vertices and edges, but not on arcs. It is known that for a prime p there is no tetravalent half-arc-transitive graphs of order p or <SUP>p2</SUP>. Xu [M.Y. Xu, Half-transitive graphs of prime-cube order, J. Algebraic Combin. 1 (1992) 275–282] classified the tetravalent half-arc-transitive graphs of order <SUP>p3</SUP>. As a continuation, we classify in this paper the tetravalent half-arc-transitive graphs of order <SUP>p4</SUP>. It shows that there are exactly p−1 nonisomorphic connected tetravalent half-arc-transitive graphs of order <SUP>p4</SUP> for each odd prime p.</P>
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Xu, Chaoliang,Liu, Xiangbing,Wang, Hongke,Li, Yuanfei,Jia, Wenqing,Qian, Wangjie,Quan, Qiwei,Zhang, Huajian,Xue, Fei Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.8
The prediction of irradiation-induced transition temperature shift for RPV steels is an important method for long term operation of nuclear power plant. Based on the irradiation embrittlement data, an irradiation-induced transition temperature shift prediction model is developed with machine learning method XGBoost. Then the residual, standard deviation and predicted value vs. measured value analysis are conducted to analyze the accuracy of this model. At last, Cu content threshold and saturation values analysis, temperature dependence, Ni/Cu dependence and flux effect are given to verify the reliability. Those results show that the prediction model developed with XGBoost has high accuracy for predicting the irradiation embrittlement trend of RPV steel. The prediction results are consistent with the current understanding of RPV embrittlement mechanism.
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