Factors Affecting Chemical Exchange Saturation Transfer Imaging on 1.5 T Clinical MRI Scanners

本文探讨1.5 T磁共振化学交换饱和转移(Chemical Exchange Saturation; Transfer,CEST)成像的影响因素.通过试管模型和临床病例,采用GE Signa HDe 1.5 T磁共振成像(Magnetic; Resonance; Imaging,MRI)扫描仪分别进行不同矩阵、激励次数、翻转角、磁化传递翻转角的CEST成像对比分析,以及不同激励次数、磁化传递翻转角的Z谱分; 析,并从成像组织、成像设备、成像技术等方面对原始图信号、酰胺质子转移(Amide Proton Transfer,; APT)信号及Z谱进行分析研究.实验结果表明1.5 T; MRI扫描仪的CEST图像信噪比相对较低,且磁场稳定性及均匀度影响了CEST成像的效果.在其他参数不变的情况下,降低采集矩阵和增加激励次数与翻转; 角可以增加原始图像信噪比.磁化传递翻转角为105?时,CEST成像效果最好.激励次数为2、磁化传递翻转角为105?时,所得数据符合组织Z谱情况.; 模型Z谱在磁化传递频率为-294 ~ -194; Hz范围可显示30%谷氨酸(Glu)、碘剂(I_(320))、纯水(H_2O)、肌酸(Cr)的信号差异,与H_2O差异最大处在-244 ~; -214 Hz.原始图像信号30%; I_(320)明显高于Glu、H_2O、Cr,Cr略低于Glu,APT图Cr略低于Glu.25例脑肿瘤的APT图呈高信号、12例脑梗塞的APT图; 呈低信号,CEST原始图像均可区分病变区域.有12例因采集时间、患者配合情况、环境及室温等影响导致CEST成像的失败.由此得出1.5; T场强下,CEST技术受到成像组织、设备、技术等因素的影响,需要进行多方面优化.在保证磁场稳定性及均匀度的情况下,优化参数的CEST成像和Z谱成; 像可以区分代谢物及其浓度.Acquisition parameters for chemical exchange saturation transfer (CEST); imaging were optimized on a GE Signa HDe 1.5 T magnetic resonance; imaging (MRI) scanner with phantoms and clinical cases. The effects of; matrix size, number of averages (NEX) and flip angles on the quality of; CEST images were assessed. It was shown that the signal-to-noise ratio; (SNR) of the CEST images acquired on the 1.5 T scanner was relatively; low, and the stability and uniformity of the B0 field affected the; outcome significantly. Reducing matrix size and increasing NEX improved; the SNR of the CEST images. Optimal flip angle for magnetization; transfer was found to be 105?. With a NEX of 2, usable Z spectra could; be obtained. The Z spectra indicated that, with the saturation pulse; frequency centered at -294 ~ -194 Hz, signal differences could be; observed for 30% Glu, I_(320), H_2O, and Cr. Maximal signal differences; were observed when the saturation pulse applied at -244 ~ -214 Hz. Amide; proton transfer (APT) imaging on patients showed that 25 cases of brain; tumor had high CEST signals, 12 cases of cerebral infarction had low; CEST signals. It was therefore possible to differentiate brain tumor; from infarction with CEST imaging. There were also 12 cases which failed; due to long acquisition time, patient movements, and temperature changes; in the scanner room.厦门市科技局科技惠民计划资助项目; 卫生部福建省卫生教育联合攻关计划资助项

Study on Corrosion Resistance of Zr-0.8Sn-1Nb-0.3Fe Alloy after Kr~+ Ion Irradiation

采用高压釜腐蚀实验研究了2种不同制备工艺下的Zr-0.8Sn-1Nb-0.3Fe合金(1#,2#)经360℃、5~25; dpa的Kr~+辐照后、在400℃/10.3 MPa过热蒸汽中的耐腐蚀性能,用透射电子显微镜(TEM)、扫描电镜(SEM)、; X射线衍射仪(XRD)分析合金腐蚀后氧化膜显微组织结构。结果表明,100; d腐蚀后,合金的腐蚀增重随着辐照剂量的增加而增加,由于1#合金中的第二相比2#合金更为细小、弥散,相同辐照剂量下,前者的腐蚀增重较低。腐蚀转折前; ,从蒸汽腐蚀侧到锆合金基体,氧化膜中的氧含量逐渐降低,靠近蒸汽侧的氧化膜主要由等轴晶形态的单斜ZrO_2组成,而基体界面处的氧化膜主要为柱状晶形; 态的四方ZrO_2和六方Zr_3O;腐蚀转折后,基体界面处的氧化膜呈"花菜"状生长,"花菜"尺寸大小与氧化膜生长速率的高低及不均匀生长趋势的大小; 呈对应关系。The corrosion resistance of Zr-0.8Sn-1Nb-0.3Fe alloys prepared by two; different processes was investigated in 400℃/18.6MPa superheated steam; by static autoclave after irradiated by 360℃ with Kr~+-irradiation of; 5~25 dpa. The microstructures of oxidation film after corrosion were; analyzed by TEM, SEM, and XRD. The results showed that the corrosion; weight-gain increased with the irradiation dose, while the weight-gain; of 1# alloy with smaller and more dispersive SPPs than 2# alloy was; lower under the same irradiation dose. Before corrosion turning, the; oxygen content in the oxidation film decreased from the steam-side to; the zirconium matrix. The oxidation film beside the steam-side was; mainly composed by equiaxied monoclinic ZrO_2 crystal, while near the; film/matrix interface by columnar quartet ZrO_2 crystal and hexagonal; Zr_3O crystal. After transition of corrosion weight, the film near the; interface grew like cauliflowers, and the size of cauliflowers were; corresponded to the growth rate and uneven growth trend of oxidation; film

Research of chemical exchange saturation transfer in brain

化学交换饱和转移(chemical exchange saturation transfer,CEST)成像是在磁化传递及化学交换理论基础上发展起来的一种磁共振成像新方法,其扩展了磁共振分子影像新领域,但还处于研究阶段。其以细胞内物质为内源性对比剂,通过水信号间接检测代谢物信息,进行组织的酸碱度成像及其各种代谢物成像。本文主要探讨MRI领域中与水相关的化学交换饱和转移现象,阐述其原理、研究现状及其在不同场强磁共振仪上脑部疾病的应用。Chemical exchange saturation transfer(CEST) imaging is a new method for magnetic resonance imaging theory of exchange in the magnetization transfer and chemical, the expansion of the new field of molecular magnetic resonance imaging,but it's still in the research stage. The intracellular substances as an endogenous contrast agent, through the indirect detection of metabolite water signal information for tissue p H imaging and imaging of various metabolites. This paper mainly discusses the chemical and water exchange in the field of MRI saturation transfer phenomenon,expounds the principle, research status and the application in brain diseases used the different field strength clinical MRI scanner.2014年厦门市科技局科技惠民计划项目(编号:3502Z20144052)~

脑型肝豆状核变性脑皮层及皮层下核团体积的磁共振研究

目的探索脑型肝豆状核变性患者脑灰质的损害。材料与方法采集30例初发且未经治疗的脑型肝豆状核变性患者脑3D T1WI图像,利用FSL软件,运用基于体素的形态学测量(voxel_based morphometry,VBM)对脑皮层...国家自然科学基金项目(编号:81671674、81871519)~

Y型聚乙二醇干扰素琢-2b注射液治疗HCV基因2/3型慢性丙型肝炎患者疗效和安全性的多中心随机对照试验研究

目的以标准剂量的聚乙二醇干扰素(Peg IFN)α-2a联合利巴韦林作为阳性对照,评价新型试验药物Y型Peg IFNα-2b注射液联合利巴韦林治疗2型/3型慢性丙型肝炎(CHC)患者的疗效和安全性。方法采用多中心、随机开放、阳性药对照的Ⅲ期临床试验,筛选符合要求的2型/3型CHC患者,按照2:1的比例随机分配到Y型Peg IFNα-2b组和Peg IFNα-2a组,同时口服利巴韦林,疗程24 w,停药随访24 w。采用Abbott Real Time HCV Genotype II检测HCV基因型,采用Cobas Taq Man实时定量PCR法检测血清HCV RNA水平。详细记录不良事件。主要疗效指标为持续病毒学应答(SVR),并进行非劣效检验。结果本试验实际入组2型/3型CHC患者255例,实际治疗241例。全分析集(FAS)数据显示,158例试验组和83例对照组患者SVR分别为85.4%(95%CI 79.94%~90.94%)和79.5%(95%CI 70.84%~88.20%,P=0.2402);对符合方案分析集(PPS)人群分析显示,试验组和对照组患者SVR分别为87.9%(95%CI 82.45%~93.27%)和85.9%(95%CI 77.82%~94.01%,P=0.7060),率差的95%可置信区间均符合非劣效标准;对PPS人群分析显示,85.8%受试者获得了早期病毒学应答(RVR),RVR的阳性预测值为90.1%;试验组和对照组不良事件发生率相似,分别为95.6%和95.2%,严重不良事件发生率分别为3.8%和3.6%。结论应用Peg IFNα联合利巴韦林治疗2型/3型CHC患者,新型试验药物Y型Peg IFNα-2b具有与对照药物Peg IFNα-2a相似的疗效和安全性。国家科技部“十二五”重大专项(编号:2012ZX10002-003)；“重大新药创制”十二五科技重大专项(编号:2012ZX09303019)

一种新型的用于数字信号处理的进化硬件原胞结构

采用CORDIC算法在单一的电路体系结构下实现了具有多种算术功能的进化电路原胞.该原胞可以作为构建此类进化硬件的基本组成模块.分析表明,采用CORDIC算法的原胞具有丰富的运算能力而只消耗较少的芯片资源,可以成为一种有前途的用于数字信号处理功能级进化电路的原胞设计的方案

Controlled bonnet polishing system for large aspheric lenses

根据大口径非球面光学元件的实际加工需要,设计并制造可控气囊抛光系统,并对机构进行运动学仿真,仿真结果表明,气囊自转轴的运动空间可以满足大口径非球面光学元件的连续进动加工要求。为了证明所设计系统的可加工性,以直径320MM的圆形平面光学元件进行加工实验。经过该气囊抛光工具24H的抛光后,工件达到较好的面型精度,光学元件的表面粗糙度由0.272λ减小到0.068λ(λ=632.8nM),PV值从1.671λ降低到0.905λ。对光学元件的实际加工实验结果表明:可控气囊抛光系统在加工过程中结构稳定性好,符合设计要求,可有效提高加工工件面型精度。The paper presents the design and manufacture of controlled bonnet polishing system used for large aspheric lenses polishing.Kinematics simulations of the designed structure show that,the workspace of the spin axis of bonnet tool can meet the requirement of large aspheric lenses polishing with continuous precession processing.A polishing experiment on the circular flat workpiece with a radius of 320 mm has been carried out.The profile accuracy of the workpiece is fine after 24-hour polishing.The surface roughness reduces from 0.272λ to 0.068λ,and the peak-to-valley value reduces from 1.671λ to 0.905λ.The results of the experiment show that the controlled bonnet polishing system is featured with high precision and high stability,meeting the design requirements,and the system can improve the profile accuracy of workpieces effectively.国家自然科学基金项目(51075343);福建省自然科学基金项目(2010J05122

NMR Based Metabonomic Data Preprocessing

数据归一化是预处理中的重要组成部分,本文采用正常大鼠与I型糖尿病模型大鼠的尿液核磁共振谱图作为测试数据,研究了线归一、面归一和模归一3种数据预处理方法对代谢组学数据PCA分析结果的影响.分析结果表明,面归一预处理方法能够更好地在PC得分图上将对照组和糖尿病组的样本分开.此外,为了有选择性的去除代谢组学数据组中的噪声变量,本文引入新的参数R来评估PC得分图的分类效果,并把它引入适应度函数,设计相应的遗传算法,对代谢组学数据进行变量选择.经过变量选择后,主成分得分图上不同类别样本的可分性提高了,而且变量数大大地减少,更有利于特征代谢物的标记与识别.Normalization is one of the most important steps of metabonomic data preprocessing.In this study,on one hand,we compared the effects of three kinds of normalization methods to the pattern recognition results in the data preprocessing,on the other hand,we evaluated evolutionary variable selection methods in improving the quality of the data clustering.Three kinds of normalization methods,i.e.Inf-Norm,1-Norm and 2-Norm,were tested on the metabonomics data sets composed of normal and diabetes I rats' urine NMR spectra data.They were found to greatly affect the outcome of the data analysis.1-Norm method performed better than the other two methods.Besides,parameter R was defined to evaluate the quality of PC scoring plot,and introduced into the fitness function of genetic algorithm(GA).The use of GA for variable selection was found to improve the data clustering quality.After GA,parts of the variables were discarding that was better to identify and recognize characteristic metabolites.卫生部卫生教育联合攻关计划项目(wkj2005-2-019);; 福建省自然科学基金(2007J0209);; 厦门市重大疾病攻关研究基金(3502Z20051027)资

量子阱结构对GaN基紫光二极管性能的影响

采用不同MQW结构在MOCVD系统上生长UV-LED外延片。对样品进行了X射线衍射、电注入发光(EL)和光致发光谱(PL)测试,通过优化LED器件材料的生长条件,获得了光发光特性一般而电发光特性优良的高质量多量子阱紫光LED外延片