腔内导管超声系统

腔内导管超声已用来评价很多病变,微探头可以置于血管腔内和非血管腔内来显示病变.二维基础上的三维重建在腔内超声图像中是一种新的方法.这篇综述将探讨腔内超声系统装置及一些进展.     

微探头导管超声换能器声束前向扫描改进的研究

将常规微探头导管侧向90#扫描声束的换能器改制,评价导管前方探测病变的可行性。将侧向90#的微探头换能器改成扫描声束前向45#或30#。通过声场测量设备和实验验证前向角度的准确性。换能器晶片发射声束前向30#的改制获得成功。改制后探头的阻抗、指向性等主要的声学物理量与改制前没有明显变化。在输尿管内,与常规扫描声束侧向90#的探头相比,大约可前向延伸探测2.8mm￣3.4mm的区域,扫描声束可以越过导管探头前端的金属盲端。从而可以观察到导管前方一定区域的病变,初步解决了输尿管狭窄和肾脏上盏内部分盲区用导管超声探测的难点。     

基于表面肌电信号的超声探头人因设计评价研究

本研究利用表面肌电采集、分析技术和Borg量表来对超声探头的人因工程学设计进行评价,为超声探头的人因工程学设计评价提供方法参考。在本研究中,邀请10个志愿者使用两个在设计样式和重量存在差异的超声探头进行模拟超声检测操作任务。使用MPl50生理信号记录仪记录前臂上的两块肌肉一指浅屈肌和桡侧腕长伸肌的肌肉活动。同时应用Borg量表对志愿者的主观反馈进行评定。结果显示使用质量较重和手柄宽度较小的超声探头时手部要承担更大的劳动负荷,更容易使局部肌肉产生疲劳,同时志愿者主观反馈结果与表面肌电测定结果存在一致相关性。这个研究方法可以作为对医疗器械手柄人因设计的评价的方法,研究结果可以作为医院在选择超声探头的指导。     

脉冲回波法与水听器法测量超声探头声场参数比较研究

针对美国ASTM E1065中提及的脉冲回波法与水听器法,通过在<10MHz频率范围内的实验,比较了这两种方法在评价平面超声探头与聚焦超声探头声场参数的一致性。实验表明,针对超声探头辐射声场参数的测量,在合理选择小球参数的基础上采用脉冲回波法与水听器法具有较好的测量一致性,而水听器法则提供了一种具有量值可溯源的超声探头评价与校准方法。     

应用血管内超声与X射线造影图像融合的血管三维重建

针对X射线血管造影和血管内超声各自显示血管形态的局限以及互补性问题,提出将两种数据进行融合,准确重建血管的方法。首先从在超声导管回撤路径起点拍摄的两个角度的造影图像对中提取出导管并进行三维重建。然后采用基于snake模型的半自动方法从各帧超声图像中提取出血管壁的内外膜边缘。最后,在Frenet-Serret标架中确定各相邻帧超声图像间的相对方位后,利用非迭代的统计优化方法确定各帧超声图像沿导管轴向的绝对方位,完成两种数据的融合。采用临床数据的实验结果验证了算法的可行性,并分析了可能存在的误差和计算成本。     

超声与微泡在血管病变治疗方面的应用

超声微泡属于"超声分子影像学"的范畴.将其携带上基因或药物后,超声与微泡不仅用于超声显像,还可用于疾病的治疗.本文现将其在血管病变治疗方面的应用作一简要综述.     

B1 心血管腔内烟雾状回声形成与红细胞缗钱叠加的关系

我们在体外实验与动物实验研究中发现,心血管腔内烟雾状回声的形成与红细胞缗钱叠加(erythrocyte rouleaux)有密切关系,兹报告如下。     

掺Nd2O3高折射率玻璃微球的制备与光学微腔效应研究

制备了掺有稀土发光材料的高折射率玻璃微球,并用XRD、Raman等进行了表征。实验结果表明,该玻璃微球粒径分布范围窄。光学性能好,其折射率约为1．93。用改造的显微拉曼光谱仪测量了微球上转换发光光谱,在其荧光光谱上发现了很强的形貌共振．并用光学微腔理论进行了解释。     

变截面背腔结构的微穿孔板吸声器的设计与研究

如何实现微穿孔板吸声结构的宽频吸声是近年来的研究热点之一。针对微穿孔板吸声结构的宽频吸声问题,本文设计了一种不规则背腔结构,并将其应用到单层和双层微穿孔板的吸声器上,对其吸声性能进行了研究。利用声电类比模型获得吸声器各部分的阻抗关系,然后通过理论计算得到吸声结构的阻抗和吸声系数。理论、仿真和实验结果表明：在不增加结构厚度的情况下,通过内层变截面隔板对背腔进行不等体积分割,可拓宽微穿孔板吸声带宽,且结构相对简单。该研究为微穿孔板吸声器的宽带低频吸声及其应用提供了新的设计思路。     

超声对鸡血与人血红细胞作用的比较研究

实验研究了1．17MHz的连续超声波作用下，人及鸡的血红细胞的溶血率、渗透脆性及膜脂过氧化水平的变化。结果表明，在声压较低时，流体间的剪切张力使得红细胞的溶血率、渗透脆性、脂质过氧化水平随作用时间及作用强度增加缓慢增长；但当声压超过空化阈值时，红细胞的溶血率随作用时间及作用强度的增加而显著增大，直至血红素完全释放细胞完全破裂；鸡红细胞的空化阈值明显高于人红细细胞，空化阈值不仅与声学参数有关，还与细胞体积和结构有关。     

关于前列腺经直肠实时灰阶超声谐波造影技术的现状及思考

1研究的重要性 前列腺癌在欧美国家是第二位高发病率的男性恶性实体肿瘤,死亡率仅次于肺癌.在国内随着前列腺特异性抗原检测的广泛应用,前列腺癌的患病率似乎愈来愈高,在我科几乎每周均遇到在超声引导下穿刺活检确诊的前列腺癌病例.     

数值模拟在乳腺疾病热成像诊断中的应用研究

本研究成果提供一种热成象软件用以迅速而有效地确诊妇女乳房疾病。本文建立了人体乳房的传热模型,编制了三维导热程序,数值模拟了正常乳房和病变乳房的三维温度场。与热图象结果进行了对比,得到了一批有实用价值的热物性数据,并对热图诊断标准进行了修正,在乳房病变热诊断方面进行了有益的探索。     

上呼吸道流场及颗粒物沉积规律的模拟

基于医学CT扫描图像得到的真实人体上呼吸道模型,采用大涡模拟方法计算了上呼吸道内部的气流流动,分析了气流流速和涡旋的特征.在拉格朗日框架下计算了可吸入颗粒物的沉积,对颗粒的局部沉积位置进行了直观显示.研究结果表明,舌咽部位涡旋和回流最多,狭窄结构处流速最大,且产生了气流喷射现象;大部分的颗粒沉积在鼻腔和喉部,颗粒粒径对沉积率有很大影响.     

彩色多普勒超声造影和实时谐波超声造影在肝肿瘤诊断中的对比研究

目的比较彩色多普勒超声造影和实时谐波灰阶超声造影在肝肿瘤诊断中的价值.方法对29例共34个肝内实质占位病变进行彩色多普勒超声造影和实时灰阶谐波超声造影检查,其中原发性肝癌(PLC)16例,转移性肝癌(MLT)4例,肝血管瘤(HCH)9例,局灶性结节性增生(FNH)5例.选用百胜Megas超声诊断仪和Bracco公司的SonoVue超声造影剂.结果注射造影剂后,彩色多普勒超声造影显示全部肝肿瘤均有不同程度的增强,能显示肿瘤内动脉血流信号比例从造影前的64.7%(22/34)提高到造影后的100%(34/34),其诊断肝癌的敏感性、特异性及准确性分别为90%(18/20)、92.9%(13/14)和91.2%(31/34).实时谐波超声造影能显示不同肝肿瘤的造影特点,并能显示肿瘤的血供灌注信号,其诊断肝癌的敏感性、特异性及准确性分别为95%(19/20)、100%(14/14)和97%(33/34).结论彩色多普勒超声造影和实时超声造影均能反映不同肝肿瘤血流改变,可帮助提高肝肿瘤超声诊断的准确性.     

A systematic review on the effectiveness of thermography in diagnosis of diseases

Collecting and analyzing appropriate information and performing comprehensive systematic studies, considering safety, effectiveness, and cost effectiveness of the technologies are prerequisites for making decisions on buying and using different diagnostic and therapeutic equipment. This study aimed to systematically identify and analyze available evidences related to the effectiveness of contact thermography technique in diagnosis of different diseases. This study was a systematic review of published and gray literature. We searched relevant databases, bibliography of related papers, and companies' websites, using appropriate search strategies and key words. The CASP tool was used by two experts to evaluate the quality of retrieved papers and inconsistencies were resolved by discussion. After removal of duplicate citations, 308 titles were identified through database searching, among which 276 were excluded on reviewing of the titles and abstracts. The full texts of the remaining papers (32) were assessed against the inclusion criteria and 14 papers were recognized qualified, which were categorized into three groups of: breast cancer, DVT, and others. The results showed although contact thermography is a safe, rapid and cheap technique to be used in screening and diagnosing different diseases, but results did not show any acceptable diagnostic value in comparison to other diagnostic techniques. It might be beneficial to use it as a complementary technique. More research is recommended in this area. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 188–193, 2013     

A comparative study on the approximate analysis of masonry structures

In this paper, numerical analysis of structural masonry subject to a uniform in-plane tensile stress/strain field is investigated employing various homogenisation techniques. Here, structural masonry is regarded as a composite material with brick, bed joints and head joints as its constituents. Assuming a perfect bonding between constituents. Assuming a perfect bonding between constituent materials, two homogenisation techniques based on the strain energy approach are applied to derive equivalent elastic moduli of masonry. Structural relationships for the constituent materials are next derived to relate strains and stresses in constituents to the average strains and stresses in the masonry. In addition, a slightly different concept of the homogenisation technique based on Eshelby's solution of the ellipsoidal inclusion problem is also applied to compare the results with the energy based methods. The tensile strength of the masonry is found on the basis of the failure of any of the constituent materials. It is shown that tensile strength is a function of the elastic parameters of brick/mortar as well as the tensile strength of mortar. These studies also show that, although initial cracking occurs under horizontal tensile forces, the ultimate strength of the panel is higher in this direction than in the vertical direction.     

A preliminary study on intravenous infusion of sodium eicosapentaenoate

Eicosapentaenoic acid (EPA) and arachidonic acid (AA), made into sodium salt solution (50 μg/ml), were used for intravenous infusion. In a preclinical study in dogs, Na-EPA lowered the activity of transminases (glutamic pyruvic transaminase [GPT], glytamic oxaloacetic transaminase [GOT]); however, Na-AA increased the activity of GPT and GOT. In the clinical study, the numbers of leukocytes and lymphocytes of volunteers increased and remained at that level for 3 to 5 days after intravenous infusion. The study indicated that an intravenous infusion of Na-EPA may have anti-inflammatory and immunomodulatory effects.     

A comparative study on the performance of meshless approximations and their integration

The goal of this research is to study the performance of meshless approximations and their integration. Two diffuse shape functions, namely the moving least-squares and local maximum-entropy function, and a linear triangular interpolation are compared using Gaussian integration and the stabilized conforming nodal integration scheme. The shape functions and integration schemes are tested on two elastic problems, an elasto-plastic problem and the inf-sup test. The elastic computation shows a somewhat lower accuracy for the linear triangular interpolation than for the two diffuse functions with the same number of nodes. However, the computational effort for this interpolation is considerably lower. The accuracy of the calculations in elasto-plasticity depends to great extend on the used integration scheme. All shape functions, and even the linear triangular interpolation, perform very well with the nodal integration scheme and locking-free behavior is shown in the inf-sup test.     

A comparative study on SWCNT and DWCNT field-effect transistors

Field-effect transistors have been fabricated using single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs), and their electrical transport properties have been studied comparatively. While a semiconducting SWCNT exhibits better field-effect characteristics than a DWCNT counterpart, the DWCNT shows more complicated response to external gate modulation. Depending on the nature of the two shells of a DWCNT, i.e., whether the shell is semiconducting (S) or metallic (M), a DWCNT device can be described as either S-S, or S-M, or M-S, or M-M. It was found that the S-S and M-M or M-S devices show similar field-effect characteristics to those found in SWCNT devices. But for S-M DWCNT devices, distinct field-effect characteristic was found and attributed to the combined effects of intershell interactions and screening by free carriers of the inner metallic shell. The S-M DWCNT devices thus provide a perfect system for studying the important intershell interaction, and information on the effect of this interaction on the electrical properties of a multi-walled carbon nanotube can be obtained by a comparative study of S-M DWCNT and S-SWCNT devices.     

A comparative study on the use of fly ash and phosphogypsum in the brick production

Over 15 million tons of fly ash (FA) and 3 million tons of phosphogypsum (PG) are produced in Turkey every year. The utilization of these industrial by-product materials is important in terms of environmental and economical issues are concerned. The main purpose of this study is to evaluate the technical possibilities of incorporating FA and PG in production of building blocks. Various mixtures were prepared by incorporating these industrial wastes by replacing clay with seven different weight proportions (0%, 5%, 10%, 15%, 20%, 25% and 30%). All specimens were fired at 1000°C peak temperature. The physical and mechanical properties of all specimens such as; unit weight, compressive strength, flexural strength, dimensional stability and water absorption values were recorded. The effect of PG incorporation on the properties of samples seems to be more dominant than the effect of FA incorporation. The test results showed that; PG incorporation increased the unit weight and mechanical strength values while lowering the water absorption values. Utilization of these wastes additives is not only for conservation of clay resources, but also an alternative solution to a difficult and expensive waste disposal problems.