共查询到20条相似文献，搜索用时 31 毫秒
1.
Objectives: To directly compare the quality of harmonic imaging (HI) and fundamental imaging (FI) in fetal echocardiography and to determine any differences in image quality between the two modalities. Methods: Fetal echocardiograms were performed with the use of FI and HI in 58 fetuses, image quality and visualization of left and right atria, left and right ventricles, mitral and tricuspid valves, aortic and pulmonary valves, left and right ventricular outflow tracts were evaluated and compared between FI and HI. Results: Mean HI scores were higher than mean FI scores (2.73±0.43 vs 2.16±0.69, P<0.001)for all the cardiovascular structures evaluated. Compared with FI, HI improved the image quality and visualization of fetal cardiac structures in subjects with both good (2.73±0.43 vs 2.88±0.32, P<0.001) and suboptimal (1.65±0.41 vs 2.58±0.47, P<0.001) echocardiographic windows. The interobserver correlation coefficient for the grading scores was 0.74 (P<0.001). Conclusions: harmonic imaging enhances and improves the image quality of fetal echocardiography; and has important potential role in cardiac imaging in the fetus. 相似文献
2.
Wenjing HUANG Shenglin LUO Dong YANG Sheng ZHANG 《Journal of Zhejiang University. Science. B》2021,22(3):171-189
The role of point-of-care(POC)diagnostics is important in public health.With the support of smartphones,POC diagnostic technologies can be greatly improved.This opportunity has arisen from not only the large number and fast spread of cell-phones across the world but also their improved imaging/diagnostic functions.As a tool,the smartphone is regarded as part of a compact,portable,and low-cost system for real-time POC,even in areas with few resources.By combining near-infrared(NIR)imaging,measurement,and spectroscopy techniques,pathogens can be detected with high sensitivity.The whole process is rapid,accurate,and low-cost,and will set the future trend for POC diagnostics.In this review,the development of smartphone-based NIR fluorescent imaging technology was described,and the quality and potential of POC applications were discussed. 相似文献
3.
Mapping paddy rice with multi-date moderate-resolution imaging spectroradiometer （MODIS） data in China 总被引：1，自引：0，他引：1
Hua-sheng SUN Jing-feng HUANG Alfredo R. HUETE Dai-liang PENG Feng ZHANG 《浙江大学学报(A卷英文版)》2009,10(10):1509-1522
The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderateresolution imaging spectroradiometer （MODIS） data in China. Paddy rice fields were extracted by identifying the unique characteristic of high soil moisture in the flooding and transplanting period with improved algorithms based on rice growth calendar regionalization. The characteristic could be reflected by the enhanced vegetation index （EVI） and the land surface water index （LSWI） derived from MODIS sensor data. Algorithms for single, early, and late rice identification were obtained from selected typical test sites. The algorithms could not only separate early rice and late rice planted in the same fields, but also reduce the uncertainties. The areal accuracy of the MODIS-derived results was validated by comparison with agricultural statistics, and the spatial matching was examined by ETM＋ （enhanced thematic mapper plus） images in a test region. Major factors that might cause errors, such as the coarse spatial resolution and noises in the MODIS data, were discussed. Although not suitable for monitoring the inter-annual variations due to some inevitable factors, the MODIS-derived results were useful for obtaining spatial distribution maps of paddy rice on a large scale, and they might provide reference for further studies. 相似文献
4.
基于雷达成像的熵函数优化方法(英文) 总被引：1，自引：0，他引：1
对ISAR成像的最小熵自聚焦(MEA)算法进行了收敛性分析. 仿真结果表明, MEA算法存在局部最优问题, 作为其代价函数的ISAR像熵函数并非多维补偿相位的下凸函数. 只有当该补偿相位矢量的初值选取合适, 使其处于像熵函数的全局最小点附近时, MEA算法才能收敛到全局最优解. 针对MEA算法的最优化问题, 给出了一种基于雷达成像的熵函数优化方法. 该方法首先采用改进的多普勒中心跟踪法估计补偿相位初值. 该初值是最大似然准则下的估计结果, 可以使初始相位位于最优解附近. 然后, 利用快速MEA 算法进行局部搜索, 得到全局最优解. 仿真结果表明, 该算法不仅实现了MEA算法的全局最优求解, 还可避免步长、阈值等参数的选择与调整. 相似文献
5.
Objective:To investigate the role of ~(99m)Tc-TRODAT-1 SPECT in diagnosis and assessing severity of idiopathicParkinson's disease(PD).Methods:Thirty-eight patients with primary,tentative diagnosis of PD and eighteen age-matchednormal controls were studied with ~(99m)Tc-TRODAT-1 SPECT imaging.The regions of interests(ROIs)were drawn manually oncerebellum(CB),occipital cortex(OC)and three transverse plane slice-views of striatums,the semiquantitative BG(back-ground)/[(OC CB)/2]were then calculated.Results:A lower uptake of ~(99m)Tc-TRODAT-1 in striatums were displayed inthirty-six out of thirty-eight PD patients by visual inspection,compared to controls.In twenty-four PD cases with HYS(Hoehn andYahr scale)stage Ⅰ,a greater loss of DAT uptake was found in striatum and its subregions contralateral striatum to the affectedlimbs than in the same regions of the controls,although the striatal uptake was bilaterally reduced.Using Spearman correlationanalysis showed that the reduction of the uptake ratios signifi 相似文献
6.
Fourier-domain rapid scanning optical delay line （RSOD） was introduced for phase modulation and depth scanning in a time-domain optical coherence tomography （TD-OCT） system. Investigation of parameter optimization of RSOD was conducted. Experiments for RSOD characterization at different parameters of the groove pitch, focal length, galvomirror size, etc. were performed. By implementing the optimized RSOD in our established TD-OCT system with a broadband light source centered at 840 nm with 50 nm bandwidth, in vivo retina imaging of a rabbit was presented, demonstrating the feasibility of high-quality TD-OCT imaging using an RSOD-based phase modulator. 相似文献
7.
LIU Dong WANG Fei HUANG Qun-xing YAN Jian-hua CHI Yong CEN Ke-fa 《浙江大学学报(A卷英文版)》2007,8(11):1853-1857
Radiative imaging of combustion flame in furnace of power plant plays an increasingly important role in combustion diagnosis. This paper presents a new method for calculating the radiative imaging of three-dimensional (3D) combustion flame based on Monte Carlo method and optical lens imaging. Numerical simulation case was used in this study. Radiative images were calculated and images obtained can not only present the energy distribution on the charge-coupled device (CCD) camera target plane but also reflect the energy distribution condition in the simulation furnace. Finally the relationships between volume ele- ments and energy shares were also discussed. 相似文献
8.
FAN Bing WANG Xiao-ying LI Miao ZHANG Yu-dong ZHANG Bao-cui LUO Jian 《重庆大学学报(英文版)》2013,12(4):147-154
The aim of this study was to compare differences in imaging quality at different injection rates of gadobutrol(Gadovist? 1.0M) for dynamic supra-aortic imaging by contrast-enhanced magnetic resonance angiography(CEM RA). In 6 healthy volunteers,dynamic CEM RA examinations were performed twice at a 7 d interval with a gadobutrol dose of 0.1 mmol given to 1 kg body mass. For the two examinations,the contrast medium was injected at rates of 1.5 mL/s and 2.0 mL/s,followed by 20 mL normal saline injected at the same rate. Using a GE Signa 3.0T M R apparatus and the time-resolved imaging of contrast kinetics(TRICKS) technique,scanning was performed continuously for 15 phases at a time resolution of about 2.4 s. Vascular reconstruction was undertaken by multiplane reconstruction and maximum intensity projection techniques. Two radiologists experienced in CEM RA diagnosis subjectively evaluated the contrast effect,vascular detail,and pseudo-shadow of all images,and graded them via a 5-point scale. With the two drug injection rates,the image quality,peak signal-to-noise ratio(SNR) and contrast-to-noise ratio(CNR) were compared for imaging of the infra-aortic arch,brachiocephalic trunk,subclavian artery(left/right),common carotid artery(left/right),internal carotid artery(left/right),and external carotid artery(left/right). Characteristics of the time-signal-intensity(T-S-I) curves were also analyzed at the two injection rates. All studies were performed successfully,without any complications. There was good image quality with both gadobutrol injection rates of 1.5 mL/s and 2.0 mL/s,and subjective scores for image quality,SNR and CNR were not significantly different between the two rates(P 0.05). The time-to-peak(TTP) from the hand dorsal vein injection site to the carotid artery ranged from 16.0 s to 27.1 s(mean 21.7 s ±3.4 s) in the 6 subjects,and was also not significantly different between the two drug injection rates(P 0.05). We conclude that dynamic CEM RA examination of the supra-aortic arch with gadobutrol injection at a rate of 1.5 mL/s was feasible,and satisfactorily reflected vascular shape and dynamic blood flow information. 相似文献
9.
从医学成像的角度,以实践为基础,总结并给出了一些直接或间接的医学光成像实际方法,讨论了不同方法的优缺点及其关联性,指出了医学中光成像的发展方向. 相似文献
10.
Kavita Dorai 《Resonance》2005,10(12):203-216
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12.
林一苏 《南昌教育学院学报》2010,25(6):195-196
随着医疗科技的发展,高精密、可靠、安全的大型医疗影像设备逐渐进入医院,医疗影像设备采用了先进的计算机控制技术,对电源系统进行严格检测控制,本文对大型医疗影像设备的安装及应用方面遇到的电源问题进行了分析。 相似文献
13.
1IntroductionSince a non-noble bulk metallic glassy alloy was dis-covered byInoue ,et al.[1]in 1988 , many stable amor-phous alloy systems with higher glass-forming abilityand lower critical cooling rates have been developed .Among them, Zr-based metallic glassy alloys are in-tenselyinvestigated because of their wider supercooledliquid region and other favorable thermodynamic andmechanical properties .In general ,surface morphologyof amorphous alloy parts is veryi mportant forindustri-al and … 相似文献
14.
Chen XC Weng J Chen XQ Du JZ Zhu MP Pan YQ Liu M 《Journal of Zhejiang University. Science. B》2008,9(9):739-746
Objective: To study the relationships among magnetic resonance imaging (MRI), histological findings, and insulin-like growth factor-I (IGF-I) in steroid-induced osteonecrosis of the femoral head in rabbits. Methods: Thirty rabbits were randomly divided into experimental Group A (n=15) and control Group B (n=15). The 7.5 mg/kg (2 ml) ofdexamethasone (DEX)and physiological saline (2 ml) were injected into the fight gluteus medius muscle twice at one-week intervals in animals of Groups A and B, respectively. At 4, 8 and 16 weeks after obtaining an MRI, the rabbits were sacrificed and the femoral head from one side was removed for histological study of lacunae empty of osteocytes, subchondral vessels, and size of fat cells under microscopy, and the femoral head from the other side was removed for enzyme-linked immunoadsorbent assay (ELISA) for IGF-I.Results: At 4, 8 and 16 weeks after treatment, no necrotic lesions were detected in Group B, while they were detected in Group A.Light microscopy revealed that the fat cells of the marrow cavity were enlarged, subchondral vessels were evidently decreased,and empty bone lacunae were clearly increased. The IGF-I levels in Group A were significantly higher than those in Group B. At 8 weeks after the DEX injection, the MRI of all 20 femora showed an inhomogeneous, low signal intensity area in the femoral head,and at 16 weeks, the findings of all 10 femora showed a specific "line-like sign". The MRI findings of all femora in Group B were normal. Conclusion: MRI is a highly sensitive means of diagnosing early experimental osteonecrosis of the femoral head. However, the abnormal marrow tissues appeared later than 4 weeks when the expression of IGF-I increased. This reparative factor has an early and important role in response to steroid-induced osteonecrosis of the femoral head, and provides a theoretical foundation for understanding the pathology and designing new therapies. 相似文献
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SAT问题(可满足性问题)是计算机科学的核心问题,研究问题的方法很多,利用极小不可满足公式的性质来研究SAT问题是近几年兴起的一个热点研究方向. 文章主要利用,(1,*)-消解和分裂方法研究了差为2的唯一极小不可满足公式集(Unique-MU(2))和差为2的对称极小不可满足公式集(SYM-MU(2))的结构和复杂度. 相似文献
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给出二次曲面成像问题的思想方法，包括二次曲面成像的问题提出、理论分析、建立物理模型和数学模型、应用前素、理论的图示。 相似文献
17.
"发现"在使用频率上高于"发觉",语法语义都有不少相近之处。两词具有瞬时实现特征,语法上的表现是不能带语态助词"的";可以引发对角色者具有影响力的意外因素,语法上体现为宾语语义构成。运用交叉理论分析二者重叠之义,在实践上很难进行。辞书释义应该反映语词实际,解释时应淡化"开始"因素,适当介入动作角色者,体现词义的主观性。 相似文献
18.
DYAKOWSKI Tom 《浙江大学学报(A卷英文版)》2005,6(12):1374-1378
INTRODUCTION In recent years, developments in the technology have led to widespread use of electrical tomography for industrial applications. Electrical tomography i based on the use of an array of the sensors located along the pipe axis or the reactor circumference Images obtained from electrical tomography show th cross-sectional spatial variation of dielectric constan or resistivity. With proper calibration these image depict the distribution of phase density or phas concentration in t… 相似文献
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研究了新试剂N-间甲苯基-N′-(对氨基苯磺酸钠)硫脲(MMPT)可与汞(Ⅱ)发生显色反应生成橙黄色的络合物,最大吸收波长位于312nm,表观摩尔吸光系数ε_(312)=6.0×10~4L·mol~(-1)·cm~(-1),Hg(Ⅱ)含量在0～30μg/25ml范围内服从比耳定律。 相似文献
20.
王玉环 《石家庄职业技术学院学报》2008,20(6):27-28
以去甲氨噻肟酸乙酯为原料,在碱性条件下与α-澳代异丁酸叔丁酯合成了头孢他啶侧链酸乙酯,分析了不同溶剂、碱的用量对反应收率的影响．较佳的反应条件为：溶剂DMF350mL,摩尔比为去甲氨噻肟酸乙酯：α-澳代异丁酸叔丁酯：无水碳酸钾=1：1．2：2,反应温度45℃,反应时间24h．在此条件下,反应收率达89．6％． 相似文献