A desktop magnetic resonance imaging system

Modern magnetic resonance imaging (MRI) systems consist of several complex, high cost subsystems. The cost and complexity of these systems often makes them impractical for use as routine laboratory instruments, limiting their use to hospitals and dedicated laboratories. However, advances in the consumer electronics industry have led to the widespread availability of inexpensive radio-frequency integrated circuits with exceptional abilities. We have developed a small, low-cost MR system derived from these new components. When combined with inexpensive desktop magnets, this type of MR scanner has the promise of becoming standard laboratory equipment for both research and education. This paper describes the development of a prototype desktop MR scanner utilizing a 0.21 T permanent magnet with an imaging region of approximately 2 cm diameter. The system uses commercially available components where possible and is programmed in LabVIEW software. Results from 3D data sets of resolution phantoms and fixed, newborn mice demonstrate the capability of this system to obtain useful images from a system constructed for approximately $13 500.     

PET–MR imaging using a tri-modality PET/CT–MR system with a dedicated shuttle in clinical routine

Tri-modality PET/CT–MRI includes the transfer of the patient on a dedicated shuttle from one system into the other. Advantages of this system include a true CT-based attenuation correction, reliable PET-quantification and higher flexibility in patient throughput on both systems. Comparative studies of PET/MRI versus PET/CT are readily accomplished without repeated PET with a different PET scanner at a different time point. Additionally, there is a higher imaging flexibility based on the availability of three imaging modalities, which can be combined for the characterization of the disease. The downside is a somewhat higher radiation dose of up to 3 mSv with a low dose CT based on the CT-component, longer acquisition times and potential misalignment between the imaging components. Overall, the tri-modality PET/CT–MR system offers comparative studies using the three different imaging modalities in the same patient virtually at the same time, and may help to develop reliable attenuation algorithms at the same time.     

Techniques for improved predictive maintenance testing ofindustrial power systems

The authors review the procedures available for the periodic testing of industrial power system components, with particular reference to the mining industry. The inherent limitations of these tests are discussed, and appropriate applications for these tests are suggested. The use of negative-sequence monitoring as an inexpensive but powerful detector of incipient failure in industrial power systems is proposed. It is emphasized that negative-sequence monitoring does not interfere with normal operations and is continuous. In laboratory experiments, it has been proven to be a sufficient indicator for detecting electrical deterioration within a squirrel-cage induction motor. It is concluded that, despite the effects of an unbalanced voltage supply on the measurement and the present uncertainty over how to compensate for these effects, negative-sequence monitoring can be a significant and powerful addition to a plant's motor testing program     

Measurement of weak electric currents in copper wire phantoms using MRI: influence of susceptibility enhancement

The use of magnetic resonance imaging (MRI)-based methods for the direct detection of neuronal currents is a topic of intense investigation. Much experimental work has been carried out with the express aim of establishing detection thresholds and sensitivity to flowing currents. However, in most of these experiments, magnetic susceptibility enhancement was ignored. In this work, we present results that show the influence of a susceptibility artefact on the detection threshold and sensitivity. For this purpose, a novel phantom, consisting of a water-filled cylinder with two wires of different materials connected in series, was constructed. Magnitude MR images were acquired from a single slice using a gradient-echo echo planar imaging (EPI) sequence. The data show that the time course of the detected MR signal magnitude correlates very well with the waveform of the input current. The effect of the susceptibility artefacts arising from the two different wires was examined by comparing the magnitudes of the MR signals at different voxel locations. Our results indicate the following: (1) MR signal enhancement arising from the magnetic susceptibility effect influences the detection sensitivity of weak current; (2) the detection threshold and sensitivity are phantom-wire dependent; (3) sub-μ A electric current detection in a phantom is possible on a 1.5-T MR scanner in the presence of susceptibility enhancement.     

Hybrid LIDAR-radar: Seeing through the scatter

Improvements in optical transmitter and receiver design and development have resulted in an increased use of optical techniques for remote sensing applications. A hybrid LIDAR-radar system has been developed that combines the detection and signal-processing techniques of radar with the optical propagation characteristics of LIDAR. The hybrid LIDAR-radar approach has been applied to both pulsed- and continuous-wave underwater laser imaging systems. These two systems are the modulated-pulse LIDAR (MPL) system and the modulated-laser line scanner (MLLS)     

Spreadsheet illustration of engineering economics

The author describes the use of an electronic spreadsheet on a desktop PC with a liquid crystal display projector for the illustration of the determination of product cost. This material is used in a junior-level laboratory course in electrical engineering. Both the spreadsheet template and underlying concepts are discussed     

省级电网桌面终端标准化管理系统研究与设计

实施信息系统桌面终端标准化管理,加强桌面终端的安全监管工作,是电网企业提高信息系统终端安全性的有效途径。为规范桌面终端运维流程,设计并开发省级电网桌面终端标准化管理系统,以提高电网企业对桌面终端的管控能力。文章首先介绍了该系统的研究背景,然后分析系统总体的设计思路与技术路线,最后对系统主要的功能模块和实际应用效果进行了详细阐述。目前,该系统已建设完成并投入使用,有效解决了桌面终端的网络管理问题,实现了桌面终端管理工作的标准化与精细化,提升了电网企业信息系统安全防护水平。     

An embedded optical tracking system for motion-corrected magnetic resonance imaging at 7T

Object

Prospective motion correction using data from optical tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel optical embedded tracking system.

Materials and methods

The home-built optical embedded tracking system performs image processing within a 7T scanner bore, enabling high speed tracking. Corrected and uncorrected in vivo MR volumes are acquired interleaved using a modified 3D FLASH sequence, and their image quality is assessed and compared.

Results

The latency between motion and correction of the slice position was measured to be (19?±?5)?ms, and the tracking noise has a standard deviation no greater than 10???m/0.005° during conventional MR scanning. Prospective motion correction improved the edge strength by 16?% on average, even though the volunteers were asked to remain motionless during the acquisitions.

Conclusion

Using a novel method for validating the effectiveness of in vivo prospective motion correction, we have demonstrated that prospective motion correction using motion data from the embedded tracking system considerably improved image quality.     

A General-Purpose MR-Compatible Robotic System

The development of a general-purpose robotic system at the Washington University for performing minimally invasive interventions with real-time MR guidance is reviewed. In this paper, the criteria upon which the system was based, and an overview of its components, the design, and prototyping of the robotic manipulator, its control components and their general integration and logic is presented. The human-machine interface and the practice of performing MR-guided interventions are described. It is concluded that when looking into the cost-effectiveness of MR-compatible systems, one cannot ignore the fact that MRI is among the most expensive imaging modalities to acquire and operate.     

Guidelines for establishing a virtual reality lab [medicalapplications]

Gives guidelines for establishing a virtual reality (VR) laboratory in the context of medical applications. In order to set up the laboratory, a user analysis and a task analysis must first be performed. A VR system's components have to be carefully selected, depending on their functionality and their use within the medical environment. The advantages of the individual components are not the only criteria for their choice; their interrelation with the system also has to be taken into account. In addition, cost is often an important limiting factor in establishing a laboratory     

A Proximal CCD imaging system for high-throughput detection ofmicroarray-based assays

The DNA microarray (chip) has stimulated the development of scanning-proximal CCD detection system that offers 10-fold enhancement of sensitivity over conventional CCD lens-based scientific imaging systems with the added benefit of quickly scanning multiple microarrays of DNA probe/target complexes. DNA microarrays have emerged as powerful tools applicable to numerous high-throughput screening assays such as genotyping, gene expression analysis, gene mutation detection, DNA sequencing, and ELISA immunoassays. DNA microarray-based assays offer tremendous potential in both diagnostic and pharmaceutical applications due to their extreme versatility and miniaturized formats. Specifically, functional applications such as population-wide genetic screening, clinical diagnostics, and determining disease risk and drug toxicity are perfectly suited for microarray formats due to the small sample volume requirements, multiplexed parallel configurations, and susceptibility to customization. Novel supporting technologies such as the Proximal CCD Imager will be essential for detection and quantification of these highly miniaturized and multiplexed microarray assays to achieve both the throughput and cost reduction goals of these demanding medical applications. For example, typical high-throughput drug discovery screening assays often require 100,000 experiments to be conducted in a year. Employing microarrays for conducting these experiments, high-throughput instruments such as the Proximal CCD Imager are necessary to alleviate the bottlenecks associated with imaging and detection. Conventional imaging systems such as a confocal laser scanner or CCD lens-based imager currently take 1-10 minutes per microarray, thereby being impractical for such demanding applications     

An Electronic Systems Laboratory

This paper describes an undergraduate electronic systems laboratory which has been developed during the past year within the School of Electrical Engineering at the Georgia Institute of Technology. The objective of this laboratory is to provide the student with the opportunity to demonstrate tangibly in the laboratory the operation and interaction of discrete devices, integrated circuits, and electronic systems which he has studied or will study in the classroom. In this laboratory students perform experimentation on (a) the characteristics and applications of two basic linear ICs, the operational amplifier and anlog multiplier; (b) the operation of a successive-approximation type A/D converter and of a D/A converter; and (c) the synergistic operation of a A/D converter, D/A converter, and an operational amplifier along with other devices and subsystems to achieve a total system function. Relatively inexpensive test equipment is used which has proven quite reliable and easy to operate. Special purpose electronic system program (ESP) boards were specifically designed, constructed, and utilized to accomodate the approximately 200 students who yearly enroll in this laboratory. This paper describes the philosophy behind this electronic systems laboratory, discusses the test equipment and ESP boards utilized, and details the specific experiments performed.     

桌面终端远程运维管理系统研究与设计

目前国家电网公司各单位桌面终端数量多、分布广、使用人员类别复杂,桌面计算机事件和问题日益增多。桌面管理人员每天面对大量的技术问题,主要通过人工电话沟通、现场排查等方式来解决,缺少强有力的信息化工具支撑,由此给桌面运维管理带来巨大的压力。文章按照运维集中化的工作要求,提出一套桌面终端远程运维管理系统,该系统将提供远程协助、文件传输、即时通信、运维审计等功能,提高终端维护效率,降低终端运维工作成本。充分利用信息运维综合监管系统,可以统一规范桌面运维操作流程,共享运维知识经验。     

A low-cost high-performance cleanroom enclosure

A conventional laboratory room was converted into a cleanroom for laser microfabrication. These simple techniques resulted in a measured class 100 environment at the surface of the optical table, well beyond the class 1000 design goal. The total conversion costs were approximately 40% the cost of a comparable commercial modular cleanroom, sufficiently inexpensive for the development of microfabrication instructional laboratories     

Long-term stability of cardiac function in normal and chronically failing mouse hearts in a vertical-bore MR system

We previously demonstrated stability of ventricular volumes and cardiac function in normal and in chronically failing mouse hearts in MR systems with a vertical-bore magnet for up to 1 h. However, in order to exploit the benefits of an increased magnetic field strength of these MR systems in more time-consuming studies required by, for example MR spectroscopy, we investigated whether cardiac function and ventricular volumes of healthy and infarcted mice would be affected in vertical position over a prolonged period. We applied high-resolution MR cine imaging on an 11.7 T vertical MR system to monitor cardiac functional parameters of normal and chronically failing mouse hearts over a period of 3 h in an upright position, with a temporal resolution of 15 min. We monitored left-ventricular volumes and cardiac functional parameters in both groups. In normal mice, we detected a decrease of left-ventricular end-systolic volumes by 8 l and an approximately 23% increase of ejection fraction over time indicating a small but detectable degree of orthostatic dysregulation. Observed changes were more pronounced in mice with heart failure. Despite significant changes in left-ventricular volumes and function, absolute values measured for all functional cardiac parameters are consistent with near-physiological conditions. Thus, mice can be studied in high-field MR systems positioned vertically for 3 h.     

桌面云在电力系统中的应用

随着国家电网公司SG186工程的全面推广,电力系统中的信息集约化要求和信息安全性要求变得越来越重要。结合桌面云的技术优势,利用桌面云部署电网业务系统,多种业务系统将实现集中化的管理,信息数据将以最高安全等级严格控制保护,同时能满足信息系统和信息设备的集约化的要求。文章在分析桌面云关键技术的基础上,对桌面云管理平台进行了设计,并探讨桌面云解决方案在电力系统中的应用与价值。     

Sequential whole-body PET/MR scanner: concept, clinical use, and optimisation after two years in the clinic. The manufacturer’s perspective

PET and MRI are established clinical tools which provide complementary information, but clinical workflow limits widespread clinical application of both modalities in combination. The two modalities are usually situated in different hospital departments and operated and reported independently, and patients are referred for both scans, often consecutively. With the advent of PET/MR as a new hybrid imaging modality there is now a possibility of addressing these concerns. There are two different design philosophies for integrated PET/MR imaging—positioning PET inside the MRI magnet or in tandem, similar to PET/CT. The Ingenuity TF PET/MR by Philips Healthcare is a sequential PET/MR tomograph combining state-of-the-art time-of-flight PET and high-field MRI with parallel transmission capabilities. In this review article we describe the technology implemented in the system, for example RF and magnetic shielding, MR-based attenuation correction, peculiarities in scatter correction, MR system optimisation, and the philosophy behind its design. Furthermore, we provide an overview of how the system has been used during the last two years, and expectations of how the use of PET/MR may continue in the years to come. On the basis of these observations and experiences we discuss the utility of the system, clinical workflow and acquisition times, and possible ways of optimization.     

The rise of embedded processing and the opportunity for open standards

Embedded processing is experiencing rapid growth. More semiconductors are sold for embedded applications than for desktop computers. Processors are found in automobiles, multimedia devices, cell phones, appliances, and soon may appear in paper (or its replacement.) General purpose computing divided the enormous expense of hardware among a large number of tasks. A well-understood, open, standard operating system core is needed if the growth of embedded systems is to continue unhindered. Operating system refer to a massive collection of programs that includes the core operating system, the graphics and user interfaces built on top of it, communications software, and the suite of user applications that are woven throughout. Only the core operating system is relevant to most dedicated devices. Linux is an operating system that is free for anyone to use or modify for their own purpose. Although its most prominent use is in desktop computers, it is used in a wide range of applications including embedded applications and large computer clusters. The principles of operating systems are well known. For desktop computers an open source operating system core may become a world standard.     

Left ventricular radial tagging acquisition using gradient-recalled-echo techniques: sequence optimization

Myocardial tagging with magnetic resonance (MR) imaging offers unique possibilities for noninvasive left ventricular (LV) strain analysis. True three-dimensional strain analysis can be achieved with tags implemented in cardiac short axis and long axis images. Spin-echo (SE) techniques have been used for these studies. However, this approach is time-consuming: images at different phases of the cardiac cycle have to be obtained in successive measurements and hence the total number of measurements equals the number of time frames. Moreover, the images are often degraded by flow and motion artifacts. The purpose of this study was to optimize a faster and more robust MR tagging sequence for use on a clinical whole-body 1 T MR system with optimal persistence of the tags during the entire cardiac cycle. The tagging pulses were implemented in gradient-recalled-echo (GRE) sequences and compared to SE-based acquisitions. The effects of the use of flow-compensating gradients, the excitation angles, and the angles of the saturation pulses have been studied with MR signal simulations and in comparative measurements in volunteers. GRE acquisitions with flow-compensating gradients are robust techniques for myocardial tagging acquisitions. Use of optimized flip angles and saturation pulses can significantly improve delineation of the tag and can be used up to at least 700 ms after the R-wave. Therefore, LV tagging with GRE acquisitions using optimized MR parameters is a robust and promising technique.     

Volumetric analysis of mice lungs in a clinical magnetic resonance imaging scanner

Small animal models are widely used to study various pathologies. Magnetic resonance imaging (MRI) allows investigation of these animals in a non-invasive way. Therefore, the aim of our study was to develop and evaluate a low-cost approach to measure lung volumes in small animal MRI using a clinical scanner and a specially designed RF coil. Five mice (three of an established emphysema model and two controls) were investigated in a 1.0-T clinical scanner using a specially built small animal saddle coil and three different three-dimensional sequences; overall imaging time was approximately 16 min. Lung volumes were calculated from these images using an interactive watershed transform algorithm for semi-automatic image segmentation. The gold standard for the volume measurement was water displacement after surgical explantation. MRI measured volumes correlated significantly with ex vivo measurements on the explanted lungs (r = 0.99 to 0.89; p < 0.05). Mean lung volume in emphysema model mice was larger than in controls. High-resolution, small animal MRI using a clinical scanner is feasible for volumetric analysis and provides an alternative to a dedicated small animal scanner.