43例歼(强)击机飞行员肾结石的诊治及医学鉴定

目的探讨歼（强）击机飞行员肾结石的诊断治疗及医学鉴定原则。方法回顾分析1982年-2008年43名患肾结石的歼（强）击机飞行员病史资料、诊治过程及医学鉴定结论。结果23名肾结石飞行员经治疗结石排出,4例确诊为肾钙化,均飞行合格;3人因结石长期治疗无效予以停飞,1人因其他疾病停飞;12例处于治疗、观察期,结论为飞行暂不合格。结论歼（强）击机飞行员（含飞行教员）患肾结石影响飞行安全,应在结石排出后方可恢复飞行远离集合系统的肾钙化灶可放飞,但应定期复查,掌握其变化情况。     

In vitro and in vivo real-time imaging with ultrasonic limited diffraction beams

Recently, there has been great interest in a new class of solutions to the isotropic/homogeneous scaler wave equation which represents localized waves or limited diffraction beams in electromagnetics, optics, and acoustics. Applications of these solutions to ultrasonic medical imaging, tissue characterization, and nondestructive evaluation of materials have also been reported. The authors report a real-time medical imager which uses limited diffraction Bessel beams, X-waves, Axicons, or conventional beams. Results (in vitro and in vivo) show that the images obtained with limited diffraction beams have higher resolution and good contrast over larger depth of field compared to images obtained with conventional focused beams. These results suggest the potential clinical usefulness of limited diffraction beams.     

Ventricular volume measurement from a multiplanar transesophagealultrasonic imaging system: an in vitro study

We have developed a system to assess the feasibility of using multiple transesophageal ultrasonic images to measure left-ventricular volume, an important variable in patient management. The system includes a special transesophageal probe with a micromanipulator for acquiring cardiac images in multiple planes with known interplanar spatial relationship and an off-line processing system to compute the volume. In vitro studies with the probe demonstrated that the distance between two targets in space can be identified within 2 mm (SD = 0.4 mm) for points in the imaging plane 3.4 mm (SD = 0.5 mm) for points not lying in the imaging plane. This gives an average accuracy of +/- 6.5% for distances greater than 4.5 cm. Comparison of ultrasonic measurements of the volume of water-filled balloons and excised hearts to the volume required to fill them, revealed a correlation coefficient of 0.992, a regression line having a slope of 1.0 and an ordinate intercept at 0.2 mL, and a standard error of the estimate of 8 mL.     

逆行输尿管软镜激光碎石治疗肾结石的荟萃分析

目的:系统评价逆行输尿管软镜激光碎石术治疗肾结石具有的优势。方法:通过检索Pubmed、Cochrane library、CBMdisc、EMBASE、CNKI等数据库有关逆行输尿管软镜激光碎石术与经皮肾镜取石术(Percutaneous nephrolithotomy,PCNL)治疗肾结石的对照试验文献,并追查纳入文献的参考文献,对符合纳入标准的研究使用统计软件RevMan5.2完成Meta分析。结果:经筛选,最后纳入8篇文献,共590例,进行Meta分析,与肾镜组比较,软镜组:(1)结石清除率(RR 0.95,95%CI 0.88至1.02,P=0.15)和术后发热率(RR 0.95,95%CI 0.54至1.67,P=0.85)无统计学意义;(2)平均手术时间延长19.11分钟(WMD19.11,95%CI 7.83至30.39,P0.05);(3)平均住院时间减少2.1天(WMD-2.1,95%CI-3.08至-1.11,P0.05);(4)出血发生率显著降低(RR 0.20,95%CI 0.06至0.68,P=0.01).结论:与PCNL比较,逆行输尿管软镜激光碎石术具有住院时间短,出血并发症低的优势。     

Minimization of imaging gradient effects in diffusion tensor imaging

A new, sample independent optimization criterion for minimizing the effect of the imaging gradients, including the directional awareness they create, is defined for diffusion tensor imaging (DTI) experiments. The DTI linear algebraic framework is expanded to a normed space to design optimal diffusion gradient schemes (DGS) in an integral fashion without separating the magnitude and direction of the DGS vectors. The feasible space of DGS vectors, for which the estimation equations are determinate, thus a hard constraint for the optimization, is parametrized. Newly generated optimal DGSs demonstrate on an isotropic sample and an ex-vivo baboon brain that the optimization goals are reached as well as a significant increase in estimation performance.     

Microprocessor-assisted solvent transfer system for effectivecontact dissolution of gallbladder stones

Dissolution of cholesterol gallbladder stones by manual lavage with methyl tert-butyl ether (MTBE) via a percutaneous indwelling gallbladder catheter is reviewed. The procedure is labor intensive and requires several hours, is associated with escape of solvent into the biliary tract, and is incomplete since residue remains. To solve these problems, a microprocessor-assisted solvent transfer (MST) system was developed. The system consists of a three-lumen catheter, dual peristaltic pumps, a pressure transducer, and a microprocessor controller which regulates pump rate according to the measured intraluminal gallbladder pressure. The two pumps simultaneously infuse and aspirate from the gallbladder via two of the catheter lumens; intraluminal pressure is monitored using the third lumen. An increase in intraluminal pressure above a set limit causes infusion to cease while aspiration continues, thus lowering the pressure and preventing overflow of gallbladder contents into the biliary tract. In vitro evaluation showed that the system's response was 156 fold faster than the natural rate of gallbladder emptying. The time required for gallstone dissolution by MTBE was measured in vitro using the MST system and found to be 48 +/- 23 (M +/- SE) min at 100 mL/min flow, 15 +/- 5 min at 150 mL/min flow, 12 +/- 4 min at 200 mL/min flow, and 6 +/- 1.4 min at 250 mL/min flow. No residual debris remained with flow rates greater than 150 mL/minute. These in vitro studies suggest that the MST system is capable of rapid, complete, and fully automatic contact dissolution of cholesterol gallbladder stones using MTBE or similar lipid solvents.     

Aberrations in temporal imaging

Recent advances in temporal imaging allow construction of systems that can expand or compress arbitrary waveforms in time, while maintaining the shape of their envelope profile with subpicosecond resolution. The process is analogous to imaging in space, with the quadratic spectral phase introduced by narrow-band dispersion performing the time-domain role of paraxial diffraction and quadratic temporal phase modulation acting as a time lens. Higher order phase terms in the dispersive networks and the time lens modulation introduce aberrations into the system. The effect each aberration has on the final temporal image varies depending on the system configuration and where the source is located in the system. A theoretical and experimental study of aberration effects is presented     

Super-resolution in PET imaging

This paper demonstrates a super-resolution method for improving the resolution in clinical positron emission tomography (PET) scanners. Super-resolution images were obtained by combining four data sets with spatial shifts between consecutive acquisitions and applying an iterative algorithm. Super-resolution attenuation corrected PET scans of a phantom were obtained using the two-dimensional and three-dimensional (3-D) acquisition modes of a clinical PET/computed tomography (CT) scanner (Discovery LS, GEMS). In a patient study, following a standard 18F-FDG PET/CT scan, a super-resolution scan around one small lesion was performed using axial shifts without increasing the patient radiation exposure. In the phantom study, smaller features (3 mm) could be resolved axially with the super-resolution method than without (6 mm). The super-resolution images had better resolution than the original images and provided higher contrast ratios in coronal images and in 3-D acquisition transaxial images. The coronal super-resolution images had superior resolution and contrast ratios compared to images reconstructed by merely interleaving the data to the proper axial location. In the patient study, super-resolution reconstructions displayed a more localized 18F-FDG uptake. A new approach for improving the resolution of PET images using a super-resolution method has been developed and experimentally confirmed, employing a clinical scanner. The improvement in axial resolution requires no changes in hardware.     

步进跟踪模式下的单脉冲雷达三维成像技术研究

逆合成孔径雷达（inverse synthetic aperture radar,ISAR）可以对飞机、舰船与空间目标等进行成像,在军事和民事应用中具有重要的意义。ISAR三维成像可以克服传统二维成像中的几何失真、方位向定标难与图像投影平面未知等问题,有利于对目标进行分类和识别,是ISAR技术的重要发展趋势之一。本文主要对单天线ISAR、干涉ISAR（interferometric ISAR,InISAR）、阵列ISAR等不同体制的三维成像进行介绍。在此基础上,对各种体制的研究现状进行了总结,并对未来的发展方向进行了分析。

     

Distinguishability in impedance imaging

Impedance imaging systems apply currents to the surface of a body, measure the induced voltages on the surface, and from this information, reconstruct an approximation to the electrical conductivity in the interior. This paper gives a detailed discussion of several ways to measure the ability of such a system to distinguish between two different conductivity distributions. The subtle differences between these related measures are discussed, and examples are provided to show that these different measures can give rise to different answers to various practical questions about system design.     

合成孔径成像激光雷达旋转目标成像

合成孔径成像激光雷达是一种新的主动式有源成像系统,它的一个突出优势是可以获得比合成孔径雷达更高的分辨率,和更接近光学图片的效果.首先,概述了理想情况下旋转目标成像的基本原理,分析了合成孔径成像激光雷达的二维分辨率.然后,针对合成孔径成像激光雷达实验中遇到的实际问题,即不能实现理想转台,会引入平动使包络相位无法对齐,进而影响成像质量,甚至无法成像.给出包络对齐和初相校正的平动补偿方法.包络对齐利用脉冲之间的相关性进行对齐;初相校正以转台模型的理想转台中心的相位为基准实现相位的对齐.最后.给出实验系统框图、工作模式、实验参数设计和最终成像效果图,对比了包络对齐和初相校正的结果,验证了系统的有效性和平动补偿的必要性.     

相干衍射成像研究进展:叠层扫描相干衍射成像和相干调制成像

相干衍射成像技术是一种无透镜计算成像技术。该技术通过迭代算法求解相位问题,直接从衍射强度数据重构物体的振幅和相位图像信息,可获得由照明光源波长和数据记录有效数值孔径决定的衍射极限分辨率。由于相干衍射成像技术不依赖于高质量光学成像元件的使用,因而适合用于深紫外、X射线以及电子束等诸多很难制作高性能成像器件的辐射源。过去20年来新型光源（冷致电子枪、第三代和第四代同步辐射光源、自由电子激光器）、单粒子计数高灵敏度、宽动态范围面阵检测器的迅猛发展,也极大地促进了相干衍射成像技术的发展。目前相干衍射成像在材料科学和生物学等热门学科方向上已经显示出了相较传统方法的独特优势,在部分应用上已经逐渐成为主流技术。文中概略回顾相干衍射成像的发展历史。重点介绍叠层扫描相干衍射成像和相干调制成像这两种快速发展的技术。     

基于虚拟现实的园林水景景石空间协调配置方法

传统园林水景景石空间协调配置一般采用规范布局搭建,无法有效释放最佳景石空间距。为有效解决该问题,引入虚拟现实技术,提出新型水景景石空间协调配置方法。利用虚拟现实技术,建立当前水景区域前导数据集,转化为VR数据流,获取数据表征,依靠数据流执行参数,环境表征、空间环境数值,综合费用等,建立约束性函数,获取景石最优排列解,利用统计领域的BioWin微观统计模型对当前园林河道坐标进行量化操作,对计算值进行空间拟合,实现景石空间的协调配置。实验结果表明,应用虚拟现实园林景石空间配置方法后,景石空间规则比提高23%,自然配置空间提高35%,可有效提高景石空间距。     

Progress in multimodality imaging: truly simultaneous ultrasound and magnetic resonance imaging

Multimodality medical imaging takes advantage of the strengths of different imaging modalities to provide a more complete picture of the anatomy under investigation. Many complementary modalities have been combined to form such systems and some are gaining use clinically. One combination that has not been developed, in large part due to technical difficulties, is a combined magnetic resonance (MR) and ultrasound (US) imaging system. Such a system offers the potential to combine the strengths of these modalities in a wide range of diagnostic and therapeutic applications. The goal of this study was to evaluate the feasibility of performing simultaneous multimodality US and MR imaging. An US imaging system capable of operation in a clinical MR imager was developed, and methods to perform simultaneous imaging were investigated. Simultaneous imaging was feasible without any mutual interference by either filtering the transmitted and received US signal, or by synchronizing data acquisition between the two imaging systems. Spatial registration between the two modalities was achieved by using a reference phantom with implanted glass beads in orthogonal planes. Excellent agreement was observed between spatial measurements of an object made with both modalities, and the feasibility of using this system in vivo was demonstrated in a rabbit model. Simultaneous US and MR imaging is achievable, and can provide complementary information about an object under investigation. This demonstration of technical feasibility and the development of a prototype system open up the potential to investigate the promising clinical applications of this combined technology.     

Multimedia communications in medical imaging

Changes in imaging technology and applications make it possible to obtain more information about patients. Information management systems, however, lag behind those achievements. The need to access and disseminate the growing volumes of patient-based information is acute. Direct effects in improving patient care, cost efficiencies in delivery, and decision making and improved communications can be gained by providing seamless views of integrated data. A prototype multimedia application that addresses work flow, human interface, and information integration and technologies is being developed. The article describes the history, need, and technical considerations involved in that development effort     

Interlacing in charge-coupled imaging devices

Solid-state imaging devices to be used in commercial broadcast TV or the Picturephone® system have to supply the video information in a 2:1 interlaced timing format. An efficient way to achieve such a readout from charge-coupled area imaging devices of the frame transfer type is described. The resolution cells of the device are elongated in the vertical dimension to extend across the distance corresponding to two scanning lines in the display. For the two fields forming a full frame the charge generated by the incident light is integrated alternately underneath different sets of electrodes. Experimental results obtained on a 64 × 106 element frame transfer array are presented and compared to theory. They show that in a three-phase structure, by alternately integrating the charge underneath electrodes number 1 and numbers 2+3 jointly, the vertical resolution can be improved by about a factor of 2. This results in a limiting resolution in the vertical direction of about 75 percent of that given by the spatial pitch of the transfer cells. The value 75 percent is characteristic of all raster scanned imaging devices and is a result of the line scanned display. The usefulness of this scheme for line imaging devices is also discussed but is dismissed as being inferior to a bilinear approach with separate interdigitated integration sites.     

Anisotropic field-of-views in radial imaging

Radial imaging techniques, such as projection-reconstruction (PR), are used in magnetic resonance imaging (MRI) for dynamic imaging, angiography, and short-T(2) imaging. They are robust to flow and motion, have diffuse aliasing patterns, and support short readouts and echo times. One drawback is that standard implementations do not support anisotropic field-of-view (FOV) shapes, which are used to match the imaging parameters to the object or region-of-interest. A set of fast, simple algorithms for 2-D and 3-D PR, and 3-D cones acquisitions are introduced that match the sampling density in frequency space to the desired FOV shape. Tailoring the acquisitions allows for reduction of aliasing artifacts in undersampled applications or scan time reductions without introducing aliasing in fully-sampled applications. It also makes possible new radial imaging applications that were previously unsuitable, such as imaging elongated regions or thin slabs. 2-D PR longitudinal leg images and thin-slab, single breath-hold 3-D PR abdomen images, both with isotropic resolution, demonstrate these new possibilities. No scan time to volume efficiency is lost by using anisotropic FOVs. The acquisition trajectories can be computed on a scan by scan basis.     

Linear inverse problems in imaging

Classical techniques for solving linear inverse problems have been presented. Our aim was to show how these classical techniques are applied in current state-of-the-art imaging systems. Moreover, we have provided a classification of the techniques into four families: FT-based, direct reconstruction, indirect reconstruction, and interpolation. We hope that this classification will guide the curious reader into a discipline with a rich bibliography and sometimes sophisticated mathematics. In this survey, we skipped complicated methods to solve inverse problems. Through our examples, we have tried to emphasize the large variety of applications of linear inverse problems in imaging. Two main examples have been examined more deeply in this survey. We hope they have helped the reader to understand the application of the general techniques in two interesting contexts: multispectral imaging and magnetic resonance imaging.