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101.
蓝建华 《中国医疗器械信息》2012,(11):40-42
目的:探讨新版国际标准ISO 8637:2010中超滤系数的分析检测方案。方法:计算滤过液流率和跨膜压之间的回归线斜率作为超滤系数。结论:通过该方案可以确定血液透析器产品的超滤系数。 相似文献
102.
103.
Jeongwon Lee Seung Hong Choi Ji‐Hoon Kim Chul‐Ho Sohn Sooyeul Lee Jaeseung Jeong 《NMR in biomedicine》2014,27(9):1046-1052
The accurate diagnosis of glioma subtypes is critical for appropriate treatment, but conventional histopathologic diagnosis often exhibits significant intra‐observer variability and sampling error. The aim of this study was to investigate whether histogram analysis using an automatically segmented region of interest (ROI), excluding cystic or necrotic portions, could improve the differentiation between low‐grade and high‐grade gliomas. Thirty‐two patients (nine low‐grade and 23 high‐grade gliomas) were included in this retrospective investigation. The outer boundaries of the entire tumors were manually drawn in each section of the contrast‐enhanced T1‐weighted MR images. We excluded cystic or necrotic portions from the entire tumor volume. The histogram analyses were performed within the ROI on normalized apparent diffusion coefficient (ADC) maps. To evaluate the contribution of the proposed method to glioma grading, we compared the area under the receiver operating characteristic (ROC) curves. We found that an ROI excluding cystic or necrotic portions was more useful for glioma grading than was an entire tumor ROI. In the case of the fifth percentile values of the normalized ADC histogram, the area under the ROC curve for the tumor ROIs excluding cystic or necrotic portions was significantly higher than that for the entire tumor ROIs (p < 0.005). The automatic segmentation of a cystic or necrotic area probably improves the ability to differentiate between high‐ and low‐grade gliomas on an ADC map. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
104.
Timo Liimatainen Juhana M. Hakumki Risto A. Kauppinen Mika Ala‐Korpela 《NMR in biomedicine》2009,22(3):272-279
The measurement of water diffusion by diffusion‐weighted MRI (DWI) in vivo offers a non‐invasive method for assessing tissue responses to anti‐cancer therapies. The pathway of cell death after anti‐cancer treatment is often apoptosis, which leads to accumulation of mobile lipids detectable by 1H MRS in vivo. However, it is not known how these discrete MR markers of cell death relate to each other. In a rodent tumour model [i.e. ganciclovir‐treated herpes simplex thymidine kinase (HSV‐tk) gene‐transfected BT4C gliomas], we studied the interrelationships between water diffusion (Trace{D}) and mobile lipids during apoptosis. Water diffusion and water‐referenced concentrations of mobile lipids showed clearly increasing and interconnected trends during treatment. Of the accumulating 1H MRS‐visible lipids, the fatty acid ? CH ?CH ? groups and cholesterol compounds showed the strongest associations with water diffusion (r2 = 0.30; P < 0.05 and r2 = 0.48; P < 0.01, respectively). These results indicate that the tumour histopathology and apoptotic processes during tumour shrinkage can be interrelated in vivo by DWI of tissue water and 1H MRS of mobile lipids, respectively. However, there is considerable individual variation in the associations, particularly at the end of the treatment period, and in the relative compositions of the accumulating NMR‐visible lipids. The findings suggest that the assessment of individual treatment response in vivo may benefit from combining DWI and 1H MRS. Absolute and relative changes in mobile lipids may indicate initiation of tumour shrinkage even when changes in tissue water diffusion are still small. Conversely, greatly increased water diffusion probably indicates that substantial cell decomposition has taken place in the tumour tissue when the 1H MRS resonances of mobile lipids alone can no longer give a reliable estimate of tissue conditions. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
105.
目的探讨甲醛染毒对雄性大鼠脏器及血清微量元素的影响.方法选用体重(110~130)g Wistar大鼠40只,随机分为4组, 染毒浓度分别为,高浓度组:(119.6±15.4) mg/m3、中浓度组:(25.2±4.6) mg/m3、低浓度组:(4.8±1.3) mg/m3和对照组;室内空气,采用静式吸入法,每天染毒1h,连续染毒9w后处死,测定大鼠各脏器的脏器系数、甲醛浓度、及大鼠血清中Fe,Cu,Zn的含量.结果高剂量组雄性大鼠肺、肾和肝脏中甲醛浓度明显高于对照组,各染毒组雄性大鼠体重明显低于对照组(P<0.05),高剂量组雄性大鼠各脏器的脏器系数与对照组比较均有显著性差异(P<0.05),雄性大鼠血清中锌含量明显降低、铜含量显著升高(P<0.05).结论长期高剂量吸入甲醛可影响雄性大鼠的生长及其血清Cu、Zn水平,并可损伤雄性大鼠的肝、肺、肾、心、脑、睾丸. 相似文献
106.
Jiang ZX Peng WJ Li WT Tang F Liu SY Qu XD Wang JH Lu HF 《World journal of gastroenterology : WJG》2008,14(38):5893-5899
AIM: To explore the diffusion gradient b-factor that optimizes both apparent diffusion coefficient (ADC) measurement and contrast-to-noise (CNR) for assessing tumor response to transarterial chemoembolization (TACE) in a rabbit model. METHODS: Twelve New Zealand white rabbits bearing VX2 tumors in the liver were treated with TACE. Diffusion-weighted imaging (DWI) with various b values was performed using the same protocol before and 3 d after treatment with TACE. ADC values and CNR of each tumor pre- and post-treatment with different b factors were analyzed. Correlation between ADC values and extent of necrosis in histological specimens was analyzed by a Pearson's correlation test.RESULTS: The quality of diffusion-weighted images diminished as the b value increased. A substantial decrease in the mean lesion-to-liver CNR was observed on both pre- and post-treatment DW images, the largest difference in CNR pre- and post-treatment was manifested at a b value of 1000 s/mm^2 (P = 0.036 ). The effect of therapy on diffusion early after treatment was shown by a significant increase in ADCs (P = 0.007), especially with large b factors (≥ 600 s/mm^2). The mean percentage of necrotic cells present within the tumor was 76.3%-97.5%. A significant positive correlation was found between ADC values and the extent of necrosis with all b values except for b200, a higher relative coefficient between ADC values and percentage of necrosis was found on DWI with bl000 and b2000 (P = 0.002 and 0.006, respectively). CONCLUSION: An increasing b value of up to 600 s/mm^2 would increase ADC contrast pre- and post-treatment, but decrease image quality. Taking into account both CNR and ADC measurement, diffusion-weighted imaging obtained with a b value of 1000 s/mm^2 is recommended for monitoring early hepatic tumor response to TACE. 相似文献
107.
108.
针对滴灌中侧翼迷宫式滴灌带的流量、灌水均匀度、肥料堵塞等问题,对4种不同规格的侧翼迷宫滴灌带进行试验,测定在清水和加肥灌水时滴头的流量及灌水均匀度。结果表明:加肥灌水时滴头流量比清水时减少,灌水均匀系数也较清水减小,4种不同结构滴头的灌水均匀度系数减小了5%~9.9%;随着灌水间隔增长,灌水次数增加,由于溶解在水中化学肥料结晶析出造成的堵塞程度逐渐增加;迷宫流道结构不同滴头的化学堵塞程度也不同。 相似文献
109.
Rody El Nawar Bertrand Lapergue Michel Piotin Benjamin Gory Raphael Blanc Arturo Consoli Georges Rodesch Mikael Mazighi Frederic Bourdain Maéva Kyheng Julien Labreuche Fernando Pico 《JACC: Cardiovascular Interventions》2019,12(4):385-391
Objectives
The aim of this study was to determine whether individual operator characteristics have an impact on reperfusion and procedural complication rates.Background
Mechanical thrombectomy (MT) is a Level IA treatment in acute ischemic stroke (AIS) patients. The operator’s effect has been found to be an independent predictor for clinical outcome and technical performance in interventional cardiology.Methods
From the ETIS (Endovascular Treatment in Ischemic Stroke) study, a prospective, multicenter, observational real-world MT registry, the authors included all AIS patients consecutively treated by MT between January 2012 and March 2017 in 3 high-volume comprehensive stroke centers by 19 operators. We assessed the effect of individual operator characteristics on successful reperfusion, defined as modified Thrombolysis In Cerebral Infarction 2b/3 at the end of MT, and procedural complications using multivariable hierarchical logistic regression models.Results
A total of 1,541 patients with anterior and posterior AIS were enrolled (mean age 67 years; median NIHSS 16). There was a significant operator effect on successful reperfusion, with an intraclass correlation coefficient of 0.036 (p = 0.046), but not on complications (intraclass correlation coefficient = 0). There was a dose–response relationship between annual operator volume and successful reperfusion rate (p = 0.003) with an adjusted odds ratio for successful reperfusion equal to 2.52 (95% confidence interval: 1.37 to 4.64) for patients treated by an operator with an annual volume ≥40 MT/year compared with those treated by an operator with <14 MT/year (first tertile). Nevertheless, this result did not translate to better clinical outcomes.Conclusions
Our data suggest that operator volume of MT/year has a positive impact on successful reperfusion in AIS patients, but not on clinical outcomes nor on complication rates. Further studies are warranted to investigate threshold procedure numbers associated with better outcomes. 相似文献110.