远程医疗系统中静止医学图像的实时传输

目的实现基于Internet的远程医疗系统中静止医学图像的实时传输与实时显示.方法用Winsock(Windows下实现TCP/IP协议的底层API)接口实现远程医疗中双方主机的连接和主机间的数据传输,使用CDIB类显示图像,并采用多线程的方法来实现在图像传输的过程中显示正传输的图像,程序采用VisualC 语言编写.结果采用本方法实现了在传输过程中图像实时显示,达到了设计目的和要求.结论本方法可以应用于远程医疗中的远程门诊和远程会诊系统并且易于扩展以支持各种图像压缩格式.     

高帧率超声成像系统中一种高信噪比扇形成像模式的实现

基于有限衍射波束的高帧率（High frame rate，HFR）成像系统能实现快速成像，但成像区域为矩形，使得远区成像的信息量受到一定的限制；同时由于通过一次发射事件成像，信噪比较低。本文提出一种方案有效地解决了这些问题。方案采用Golay互补序列作为激励信号及两次发射与接收过程，每个发射事件同时发射两个不同角度的平面波。在对接收信号进行处理时。利用Golay互补序列良好的正交性及其相关函数为冲击函数特征，不仅显著地提高了接收信号的信噪比，而且有效地分离出相对于不同发射角度的两个平面波的回波信号。然后分别用HFR成像方法重建不同区域图像，最后合成一帧扇形成像。     

Real-time emergency telemedicine system: prototype design and functional evaluation

In this paper, an emergency telemedicine system was designed for the transmission of real-time multimedia for remote consultation, including radiological images, patient records, video-conferencing, full-quality video, ECG, BP, respiration, temperature, SpO(2), systolic and diastolic pressures and heart rate. The standardized, modular, software-based design architecture, without resorting to external hardware compression boards, enables the low-cost implementation of the telemedicine system, using the unified, systematic and compact integration of multimedia on general personal computers. Experimental tests on local networks analyze the technical aspects of designed systems, and inter-hospital experiments demonstrate its clinical usefulness.     

Cost-effective handling of digital medical images in the telemedicine environment

BACKGROUND: This paper concentrates on strategies for less costly handling of medical images. Aspects of digitization using conventional digital cameras, lossy compression with good diagnostic quality, and visualization through less costly monitors are discussed. METHOD: For digitization of film-based media, subjective evaluation of the suitability of digital cameras as an alternative to the digitizer was undertaken. To save on storage, bandwidth and transmission time, the acceptable degree of compression with diagnostically no loss of important data was studied through randomized double-blind tests of the subjective image quality when compression noise was kept lower than the inherent noise. A diagnostic experiment was undertaken to evaluate normal low cost computer monitors as viable viewing displays for clinicians. RESULTS: The results show that conventional digital camera images of X-ray images were diagnostically similar to the expensive digitizer. Lossy compression, when used moderately with the imaging noise to compression noise ratio (ICR) greater than four, can bring about image improvement with better diagnostic quality than the original image. Statistical analysis shows that there is no diagnostic difference between expensive high quality monitors and conventional computer monitors. CONCLUSION: The results presented show good potential in implementing the proposed strategies to promote widespread cost-effective telemedicine and digital medical environments.     

基于VTK和ITK环境的超声图像三维重建

背景：医学图像的三维模型,能够准确的三维结构在临床诊断上凸显重要性。 目的：对连续多帧的超声图像进行三维结构重建。 方法：利用可视化工具VTK和图像的配准分割工具ITK,在VC++的平台下,采取直接体绘制的方法,对连续多帧的DICOM医学超声图像进行了三维重建,并且用户可以利用鼠标与图片进行交互,实现任意角度的旋转。 结果与结论：合成体绘制在重建中的效果较优,相对而言更适合超声图像的三维重建。     

Displaying radiologic images on personal computers: Image storage and compression: Part 1

This is the third article of our series for radiologists and imaging scientists on displaying, manipulating, and analyzing radiologic images on personal computers. Part 1 of this article discusses image storage and reviews the basic concepts of information theory and image compression; part 2 will discuss specific methods of image compression. There are a wide variety of removable storage devices available to users who need to archive radiologic images on their personal computers. Tape drives have potentially very large storage capacity but slow performance. Removable SyQuest (SyQuest Technology, Femont, CA) and Bernoulli disks have near hard disk performance and can store from 100 to 150 Mbytes. Magneto-optical drives can store nearly 1 Gb on a 5.25″ disk, with somewhat slower performance. Selecting the most appropriate storage solution requires a careful balance of the user's requirements, including performance, storage needs, cost and compatibility with other users. Despite the advances in low cost high capacity storage technology, image compression remains a crucial technology for modern diagnostic radiology because digital images require such large amounts of storage. Image compression is possible because radiologic images have relatively low entropy (high information content) compared with random noise. Image compression is classified as lossless (nondestructive) or lossy (destructive). Lossless image compression commonly achieve compression ratios of 1.5:1 to 3:1 (33% to 67%), whereas lossy compression can compresses images from 3:1 to 30:1 (67% to 97%). Many lossless compression methods are enhanced by first creating a difference image using discrete pulse code modulation. All compression methods are adversely affected by image noise.     

Watermark Compression in Medical Image Watermarking Using Lempel-Ziv-Welch (LZW) Lossless Compression Technique

In teleradiology, image contents may be altered due to noisy communication channels and hacker manipulation. Medical image data is very sensitive and can not tolerate any illegal change. Illegally changed image-based analysis could result in wrong medical decision. Digital watermarking technique can be used to authenticate images and detect as well as recover illegal changes made to teleradiology images. Watermarking of medical images with heavy payload watermarks causes image perceptual degradation. The image perceptual degradation directly affects medical diagnosis. To maintain the image perceptual and diagnostic qualities standard during watermarking, the watermark should be lossless compressed. This paper focuses on watermarking of ultrasound medical images with Lempel-Ziv-Welch (LZW) lossless-compressed watermarks. The watermark lossless compression reduces watermark payload without data loss. In this research work, watermark is the combination of defined region of interest (ROI) and image watermarking secret key. The performance of the LZW compression technique was compared with other conventional compression methods based on compression ratio. LZW was found better and used for watermark lossless compression in ultrasound medical images watermarking. Tabulated results show the watermark bits reduction, image watermarking with effective tamper detection and lossless recovery.     

Technical dependability of obstetric ultrasound transmission via ISDN.

OBJECTIVE: To evaluate the dependability of a live telemedicine link for the transmission of obstetric ultrasonograms using a commercial telephone network. MATERIALS AND METHODS: We established an integrated services digital network (ISDN), consisting of three dedicated telephone lines from three satellite offices, to our central prenatal diagnostic center. All patients had a sonographic evaluation recorded on videotape by a trained sonographer. A live interactive video telemedicine link was then established, and a perinatologist directed the sonographer through the scan. A report was issued on the basis of the telemedicine examination. The number of calls required to obtain satisfactory real-time images was recorded, as were the reasons for suboptimal transmissions. The first 150 transmissions were excluded from this study. The results in the subsequent 100 patients who agreed to participate were analyzed. RESULTS: We were able to provide obstetric interpretations in all 100 patients scheduled to be examined using the telemedicine link. A single connection was required in 85 cases, two calls in 5 cases, three calls in 8 cases, four calls in 1 case, and five calls in another case. A repeat call was required in 20 cases because of poor image transmission; other repeat calls were caused by failure to connect (5 cases), calls disconnected (2 cases), and no image transmission (2 cases). CONCLUSIONS: The provision of telemedicine services for obstetric ultrasonography in the community is feasible, but the need for repeat connections because of technical failures needs to be incorporated into cost and time analyses in order to provide a measure of the system's efficiency.     

Quantitative DNA ploidy analysis of breast carcinoma: A study of the effects of joint photographer experts group (JPEG) compression on DNA ploidy images

Telepathology usage in the past has typically been a qualitative procedure rather than a quantitative measurement. DNA ploidy using image analysis has been favorably compared to DNA ploidy analysis by flow cytometry in numerous publications. A step from DNA ploidy analysis using conventional image analysis to DNA ploidy analysis using stored images allows DNA ploidy analysis by image cytometry to become a powerful tool in telepathology. Remote DNA ploidy analysis using stored images has an impact on the field of pathology, as not every hospital or laboratory can afford to perform this type of specialized testing. However, images have large data files and require lengthy transmission times over communication systems to other computers. Joint Photographer Experts Group (JPEG) compression is a computer algorithm that allows the file size of an image to be reduced in order to decrease transmission times to another computer. A study was initiated to investigate the effects of JPEG compression on images of Feulgen stained breast tumor touch preps and the resulting DNA ploidy histograms. Diagn Cytopathol 1996;15:231–236. © 1996 Wiley-Liss, Inc.     

A uniform format for ocular imaging devices.

PURPOSE: To develop a uniform file format of ocular imaging data, including, but not limited to, ultrasound biomicroscopy, optical coherence tomography, and nerve fiber analyzer, capable of being transmitted via Internet or intranet for collaborative research and telemedicine use. METHOD: File filters were developed as dynamic link libraries (DLLs). These can read the original raw data format of each ocular imaging device. A data file format was also designed to describe these raw data uniformly in three different types of compression: noncompressed, run length compression, and differential pulse code modulation (DPCM). These three file formats were then tested in the following aspects: file size, speed of reading, and speed of writing. RESULTs: Run length compression failed to compress raw data, while DPCM compressed raw data successfully (< or =35.5%). The speed of reading and writing files was slowest in DPCM. However, the actual time of reading and writing was fast enough (<0.6 s) for daily work regardless of file compression methods. CONCLUSION: The format designed has robust potential to be the standard file format for transmission of any ocular imaging raw data.     

A Mobile Tele-Radiology Imaging System with JPEG2000 for an Emergency Care

The aim of this study was to design a tele-radiology imaging system for rapid emergency care via mobile networks and to assess the diagnostic feasibility of the Joint Photographic Experts Group 2000 (JPEG2000) radiological imaging using portable devices. Rapid patient information and image exchange is helpful to make clinical decisions. We assessed the usefulness of the mobile tele-radiology system by measuring both a quantitative method, PNSR calculation, for image qualities, and its transmission time via mobile networks in different mobile networks, respectively; code division multiple access evolution-data optimized, wireless broadband, and high-speed downlink packet access; and the feasibility of the JPEG2000 computed tomography (CT) images by qualitatively assessing with the Alberta stroke program early CT score method with 12 CT image cases (seven normal and five abnormal cases). We found that the quality of the JPEG2000 radiological images was satisfied quantitatively and was judged as acceptable qualitatively at 5:1 and 10:1 compression levels for the mobile tele-radiology imaging system. The JPEG2000-format radiological images achieved a fast transmission while maintaining a diagnosis quality on a portable device via mobile networks. Unfortunately, a PDA device, having a limited screen resolution, posed difficulties in reviewing the JPEG2000 images regardless of the compression levels. An ultra mobile PC was preferable to study the medical image. The mobile tele-radiology imaging systems supporting JPEG2000 image transmission can be applied to actual emergency care services under mobile computing environments.     

Ultrasound tomography imaging of radiation dose distributions in polymer gel dosimeters: preliminary study

A novel imaging system for investigation of absorbed dose distributions in radiotherapy polymer gel dosimeters using ultrasound is introduced. A prototype transmission ultrasound computed tomography (UCT) imaging system is developed and evaluated. The imaging capabilities of the system are assessed through investigation of an irradiated polyacrylamide gel test phantom. Images based on transmitted signal amplitude and time of flight (TOF) of the ultrasonic signal through the phantom are reconstructed using a filtered backprojection technique. In general, the reconstruction of the square field in the TOF image was superior to the transmission image, however, transmission images displayed superior contrast to TOF images. The image quality achieved with this prototype system is promising and could be significantly enhanced through improvements, in particular through the development of more sophisticated experimental equipment. It is concluded that UCT is a viable technique for imaging absorbed dose distributions in polymer gel dosimeters and investigations are continuing to further improve the system.     

Lossless Compression on MRI Images Using SWT

Medical image compression is one of the growing research fields in biomedical applications. Most medical images need to be compressed using lossless compression as each pixel information is valuable. With the wide pervasiveness of medical imaging applications in health-care settings and the increased interest in telemedicine technologies, it has become essential to reduce both storage and transmission bandwidth requirements needed for archival and communication of related data, preferably by employing lossless compression methods. Furthermore, providing random access as well as resolution and quality scalability to the compressed data has become of great utility. Random access refers to the ability to decode any section of the compressed image without having to decode the entire data set. The system proposes to implement a lossless codec using an entropy coder. 3D medical images are decomposed into 2D slices and subjected to 2D-stationary wavelet transform (SWT). The decimated coefficients are compressed in parallel using embedded block coding with optimized truncation of the embedded bit stream. These bit streams are decoded and reconstructed using inverse SWT. Finally, the compression ratio (CR) is evaluated to prove the efficiency of the proposal. As an enhancement, the proposed system concentrates on minimizing the computation time by introducing parallel computing on the arithmetic coding stage as it deals with multiple subslices.     

Projection-Based Medical Image Compression for Telemedicine Applications

Recent years have seen great development in the field of medical imaging and telemedicine. Despite the developments in storage and communication technologies, compression of medical data remains challenging. This paper proposes an efficient medical image compression method for telemedicine. The proposed method takes advantage of Radon transform whose basis functions are effective in representing the directional information. The periodic re-ordering of the elements of Radon projections requires minimal interpolation and preserves all of the original image pixel intensities. The dimension-reducing property allows the conversion of 2D processing task to a set of simple 1D task independently on each of the projections. The resultant Radon coefficients are then encoded using set partitioning in hierarchical trees (SPIHT) encoder. Experimental results obtained on a set of medical images demonstrate that the proposed method provides competing performance compared with conventional and state-of-the art compression methods in terms of compression ratio, peak signal-to-noise ratio (PSNR), and computational time.     

基于对称区域生长算法的超声医学图像分割方法

提出了一种基于对称区域生长算法的超声医学图像的分割方法。该方法分为三步。首先,通过采用自适应加权中值滤波抑制超声医学图像本身固有的Speckle噪声,然后从图像的第一行开始扫描整个图像,并应用生长准则进行区域的生长与合并,生长完成之后应用种子准则标定感兴趣区域,从而得到最后的分割结果。通过图像的分割实验确定了一套对于超声医学图像适用的生长和合并准则。对心脏B型超声医学图像分割的实验结果显示,该方法具有良好的性能。     

Assessment of Numerical Simulation Strategies for Ultrasonic Color Blood Flow Imaging,Based on a Computer and Experimental Model of the Carotid Artery

Ultrasonic Doppler techniques are well established and allow qualitative and quantitative flow analysis. However, due to inherent limitations of the imaging process, the actual flow dynamics and the ultrasound (US) image do not always correspond. To investigate the performance of ultrasonic flow imaging methods, computational fluid dynamics (CFD) can play an important role. CFD simulations can be directly processed to mimic ultrasonic images or can be further coupled to ultrasound simulation models. We studied both approaches in the clinically relevant setting of a carotid artery using color flow images (CFI). The first order approach consisted of producing ultrasound images by color-coding CFD-simulations. For the second order approach, CFI was simulated using an ultrasound simulator, which models blood as a collection of point scatterers moving according to the CFD velocity fields. Color flow images were also measured in an experimental setup of the same carotid geometry for comparison. Results showed that during dynamic stages of the cardiac cycle, realistic ultrasound data can only be achieved when incorporating both the dynamic image formation and the measurement statistics into the simulations.     

基于图像对比度分析的自适应超声声速优化

本文提出一种基于图像对比度分析的自适应声速优化技术,从而实时得到对比度增强、组织结构清晰可见的超声影像。论文首先描述超声系统动态延迟聚焦的波束形成过程,并引入系统声速以及组织真实声速等概念,进而讨论其两者不匹配对图像品质的影响。介绍图像灰度值表示的对比度之后,论文阐述了准确估计与组织声速一致的系统声速的基本原理。最后,论文通过已知声速的仿人体组织体模和真实人体组织超声影像来验证,并与已有声速优化方法进行比较。实验结果不仅表明本研究所估计的声速是准确的,而且算法运算速度亦适用于超声系统的实时应用。     

离体甲状腺的高频超声成像和组织定征

本文用C扫高频超声显微镜对离体人体甲状腺的超声特性作了系统的研究。超声频段范围为25-55MHz。为定量对生物组织进行定征,本实验室建立一套高频超声显微镜系统,对政治客病变的离体人体甲状腺组织的三个典型的声参量进行了测量。测量结果表明：正常甲状腺的声速为1520m/s,在35MHz,超声衰减系数为3.4dB/mm,背向声散射系数为0.00157/(Srmm),而病变甲状腺滤泡性腺瘤的速为1650m/s,超声衰减系数为6.6dB/mm,约为正常的2倍,背向声散射系数为0.00387/(Srmm),比正常的大1倍半,除此之外,我们还得到正常和病变甲状腺的高频超声图象,并与组织的切片结果作了对比。     

Magnetic Resonance Imaging Research in Sub-Saharan Africa: Challenges and Satellite-Based Networking Implementation

As part of an NIH-funded study of malaria pathogenesis, a magnetic resonance (MR) imaging research facility was established in Blantyre, Malaŵi to enhance the clinical characterization of pediatric patients with cerebral malaria through application of neurological MR methods. The research program requires daily transmission of MR studies to Michigan State University (MSU) for clinical research interpretation and quantitative post-processing. An intercontinental satellite-based network was implemented for transmission of MR image data in Digital Imaging and Communications in Medicine (DICOM) format, research data collection, project communications, and remote systems administration. Satellite Internet service costs limited the bandwidth to symmetrical 384 kbit/s. DICOM routers deployed at both the Malaŵi MRI facility and MSU manage the end-to-end encrypted compressed data transmission. Network performance between DICOM routers was measured while transmitting both mixed clinical MR studies and synthetic studies. Effective network latency averaged 715 ms. Within a mix of clinical MR studies, the average transmission time for a 256 × 256 image was ~2.25 and ~6.25 s for a 512 × 512 image. Using synthetic studies of 1,000 duplicate images, the interquartile range for 256 × 256 images was [2.30, 2.36] s and [5.94, 6.05] s for 512 × 512 images. Transmission of clinical MRI studies between the DICOM routers averaged 9.35 images per minute, representing an effective channel utilization of ~137% of the 384-kbit/s satellite service as computed using uncompressed image file sizes (including the effects of image compression, protocol overhead, channel latency, etc.). Power unreliability was the primary cause of interrupted operations in the first year, including an outage exceeding 10 days.     

An investigation of the use of transmission ultrasound to measure acoustic attenuation changes in thermal therapy

The potential of using a commercial ultrasound transmission imaging system to quantitatively monitor tissue attenuation changes after thermal therapy was investigated. The ultrasound transmission imaging system used, the AcoustoCam (Imperium Inc., MD) allows ultrasonic images to be captured using principles similar to that of a CCD-type camera that collects light. Ultrasound energy is focused onto a piezoelectric array by an acoustic lens system, creating a gray scale acoustic image. In this work, the pixel values from the acoustic images were assigned acoustic attenuation values by imaging polyacrylamide phantoms of varying known attenuation. After the calibration procedure, data from heated polyacrylamide/bovine serum albumin (BSA) based tissue-mimicking (TM) phantoms and porcine livers were acquired. Samples were heated in water at temperatures of 35, 45, 55, 65, and 75°C for 1 h. Regions of interest were chosen in the images and acoustic attenuation values before and after heating were compared. An increase in ultrasound attenuation was found in phantoms containing BSA and in porcine liver. In the presence of BSA, attenuation in the TM phantom increased by a factor of 1.5, while without BSA no significant changes were observed. The attenuation of the porcine liver increased by up to a factor of 2.4, consistent with previously reported studies. The study demonstrates the feasibility of using a quantitative ultrasound transmission imaging system for monitoring thermal therapy.