Is image selection a useful strategy to decrease the transmission time in teleradiology? A study using 100 emergency cranial CTs

This study examines the suitability of working with a selection of images in a teleradiology consulting system in neurological or neurosurgical emergency situations. The teleradiology system was based on IBM-compatible personal computers, video digitization for data acquisition, and data transmission by Integrated System Digital Network. Forty normal and 60 abnormal emergency cranial computed tomograms were shown to a radiologist on call who presented all cases he regarded as pathologic to a neuroradiologic expert by teleradiology. To reduce transmission time, only a selection of images from the CT study was presented (up to four images per case). For each case the on-call radiologist's diagnosis (D(on-call)), the expert's diagnosis on the teleradiology screen (D(monitor)), and the expert's diagnosis on the original film (D(original)) was documented, together with an estimation of the agreement between those diagnoses. There was clinically relevant disagreement between the on-call radiologist's diagnosis and the neuroradiologist's diagnosis based on the image selection on the teleradiology monitor in 23% of cases. A clinically important discrepancy between the neuroradiologist's diagnosis based on the image selection and his diagnosis using the original films was found in 30% of cases. This was due to the presence of clinically relevant information on images not transferred by the on-call radiologist. Image quality of the transferred images was sufficient in all cases. Drastic selection of images from a complete CT study leads to a high rate of incorrect diagnoses and is not appropriate to reduce transmission time in teleradiology.     

JPEG quality transcoding using neural networks trained with a perceptual error measure

A JPEG Quality Transcoder (JQT) converts a JPEG image file that was encoded with low image quality to a larger JPEG image file with reduced visual artifacts, without access to the original uncompressed image. In this article, we describe technology for JQT design that takes a pattern recognition approach to the problem, using a database of images to train statistical models of the artifacts introduced through JPEG compression. In the training procedure for these models, we use a model of human visual perception as an error measure. Our current prototype system removes 32.2% of the artifacts introduced by moderate compression, as measured on an independent test database of linearly coded images using a perceptual error metric. This improvement results in an average PSNR reduction of 0.634 dB.     

Impact of scale standardization on images of digital radiography systems

OBJECTIVES: To test the effect of altering image size on diagnostic quality. METHODS: Endodontic files, size 10 and 15 were prepared to full root length and 1.5 mm short, in upper and lower molars and premolars. Digital images of the Sidexis (S) and Visualix/Vixa (V) system were reduced in size to Digora (D) scale, and the D images were enlarged to S scale. ROC analysis was performed and data analysed with MANOVA statistics. RESULTS: Assessment of root canal length with file size 10 was less accurate for the S images reduced in size, compared with the original S images (P < 0.011). All other differences were not significant (P > 0.081). CONCLUSIONS: Relevant diagnostic information may be lost when images are reduced in size. Therefore, for optimal presentation, the smaller images should be enlarged rather than the larger ones reduced.     

Design of an emergency teleradiology system based on progressive transmission

In clinical surgery, there are frequent needs for communication between the house staff and the attending physician in an emergency situation. To overcome the limitation of voice communication through the telephone line, we have designed an 'emergency teleradiology system' which can be used for emergency surgical and medical decision making. This system can transmit the high quality images of CT, MRI, and other X-ray data using a PC attached to a modem through the conventional telephone line. It is based on the progressive transmission system which enables the successive update of a received image. The iterative residual coding/decoding algorithm efficiently compresses the image to maximally utilize the low bandwidth PSTN channels. This system also satisfies design requirements such as low-cost, ease of operation, fast transmission, and interactive image communication including voice. Test results using several CT, MR, and X-ray images evaluate the compression performance, image quality, transmission time and computational time of the coding and decoding processes, thus demonstrate the usefulness of this system in an emergency situation.     

Personal computer teleradiology interhospital image transmission to facilitate tertiary pediatric telephone consultation and patient transfer: soft-tissue lateral neck and elbow radiographs

Although teleradiology systems are available commercially, they are expensive ($30,000), and different makes are incompatible with each other, making them unusable for interhospital image transfers. Standard components were added to a personal computer (PC) to build a functional teleradiology unit capable of interhospital image transmission at a low cost ($600 upgrade). This PC teleradiology system was studied to assess its accuracy in the interpretation of soft-tissue lateral neck x-rays with epiglottitis or retropharyngeal abscesses and elbow x-rays with joint effusions, fractures, or both. A radiologist and a pediatric emergency physician were asked to read the PC teleradiology images. Both physicians read 13 of 13 soft-tissue lateral neck x-rays and 15 of 15 elbow x-rays correctly. This study supports the premise that PC teleradiology can be used to facilitate telephone consultation and patient transfers between tertiary pediatric emergency centers by transmitting pertinent radiographic information over a phone line. Although verbal communication can often suffice in a telephone consultation or transfer, there are many instances when visualizing a radiographic image such as an x-ray or computed tomography scan can provide important information that cannot be optimally described verbally. Rural hospitals can form interhospital image transmission links with tertiary center resources. Tertiary centers may elect to organize interhospital image transmission and referral networks with their rural hospital sources.     

Wavelet versus JPEG (Joint Photographic Expert Group) and fractal compression. Impact on the detection of low-contrast details in computed radiographs

RATIONALE AND OBJECTIVES: The aim of this study was to evaluate different lossy image compression algorithms in direct comparison. METHODS: Computed radiographs were reviewed after compression with Wavelet, Fractal, and Joint Photographic Expert Group (JPEG) algorithms. For receiver operating characteristic (ROC) analysis, 54 thoracic computed radiographs (31 showing pulmonary nodules) were compressed with a ratio of 1:60. Five images of a test-phantom were coded at 1:13. All images were reviewed on a PC. Uncompressed images were reviewed at a PC and at a radiologic workstation (with image processing). RESULTS: For thorax images, decrease of diagnostic accuracy was significant with Wavelets. Fractal performed worse than Wavelets. No ROC curve was observed for JPEG due to poor image quality. No diagnostic loss was noted comparing PC and Workstation review. For low-contrast details of the phantom, results of Wavelet compression were equal to uncompressed images. Fewer true positives and increased true negatives were noted with Wavelets though. Wavelets were superior to JPEG, and JPEG images were superior to Fractal. Workstation review was superior to PC review. CONCLUSIONS: Only Wavelets provided accurate review of low-contrast details at a compression of 1:13. Frequency filtering of Wavelets affects contrast even at a low compression ratio. JPEG performed better than Fractal at low and worse at high compression ratio.     

Spatial resolution of body surface potential maps and magnetic field maps: a simulation study applied to the identification of ventricular pre-excitation sites

Telemedicine is defined as the "delivery of health care and sharing of medical knowledge over a distance using telecommunication systems." The concept of telemedicine is not new. Beyond the use of the telephone, there were numerous attempts to develop telemedicine programs in the 1960s mostly based on interactive television. The early experience was conceptionally encouraging but suffered inadequate technology. With a few notable exceptions such as the telemetry of medical data in the space program, there was very little advancement of telemedicine in the 1970s and 1980s. Interest in telemedicine has exploded in the 1990s with the development of medical devices suited to capturing images and other data in digital electronic form and the development and installation of high speed, high bandwidth telecommunication systems around the world. Clinical applications of telemedicine are now found in virtually every specialty. Teleradiology is the most common application followed by cardiology, dermatology, psychiatry, emergency medicine, home health care, pathology, and oncology. The technological basis and the practical issues are highly variable from one clinical application to another. Teleradiology, including telenuclear medicine, is one of the more well-defined telemedicine services. Techniques have been developed for the acquisition and digitization of images, image compression, image transmission, and image interpretation. The American College of Radiology has promulgated standards for teleradiology, including the requirement for the use of high resolution 2000 x 2000 pixel workstations for the interpretation of plain films. Other elements of the standard address image annotation, patient confidentiality, workstation functionality, cathode ray tube brightness, and image compression. Teleradiology systems are now widely deployed in clinical practice. Applications include providing service from larger to smaller institutions, coverage of outpatient clinics, imaging centers, and nursing homes. Teleradiology is also being used in international applications. Unresolved issues in telemedicine include licensure, the development of standards, reimbursement for services, patient confidentiality, and telecommunications infrastructure and cost. A number of states and medical boards have instituted policies and regulations to prevent physicians who are not licensed in the respective state to provide telemedicine services. This is a major impediment to the delivery of telemedicine between states. Telemedicine, including teleradiology, is here to stay and is changing the practice of medicine dramatically. National and international communications networks are being created that enable the sharing of information and knowledge at a distance. Technological barriers are being overcome leaving organizational, legal, financial, and special interest issues as the major impediments to the further development of telemedicine and realization of its benefits.     

Use of store and forward technology for vascular nursing teleconsultation service

Accurate assessment is critical in planning appropriate therapeutic management of a patient with a vascular wound. However, several factors may inhibit wound assessment by trained professionals or subspecialists. Multiple co-morbidities and lack of transportation and finances contribute to problems with access to specialty clinics for both rural and urban patients with vascular disease. To assess the application of telemedicine in meeting the needs of rural patients with vascular disease, the vascular nurse clinician of a regional medical network was incorporated into a telemedicine research project that used a still-image transmission system known as the Picasso telephone, which allows a diagnostic quality image to be transmitted over a regular telephone line. Telephone consultation between sender and receiver occurs simultaneously at the time of image transmission. Because images can be collected and stored for future reference, this technology is commonly called "store and forward" technology. The application of advanced technology in a rural health care environment has the potential to reduce costs for both patient and managed care insurance plans, allow for expert consultation from distant centers, and promote collegiality and learning among professionals.     

Inhibition of beta-oxidation by 3-mercaptopropionic acid produces features of Reye''s syndrome in perfused rat liver

PURPOSE: To evaluate the effects of lossy image (noninvertible) compression on diagnostic accuracy of thoracic computed tomographic images. MATERIALS AND METHODS: Sixty images from patients with mediastinal adenopathy and pulmonary nodules were compressed to six different levels with tree-structured vector quantization. Three radiologists then used the original and compressed images for diagnosis. Unlike many previous receiver operating characteristic-based studies that used confidence rankings and binary detection tasks, this study examined the sensitivity and predictive value positive scores from nonbinary detection tasks. RESULTS: At the 5% significance level, there was no statistically significant difference in diagnostic accuracy of image assessment at compression rates of up to 9:1. CONCLUSION: The techniques presented for evaluation of image quality do not depend on the specific compression algorithm and provide a useful approach to evaluation of the benefits of any lossy image processing technique.     

Palisaded encapsulated neuroma of the nasal fossa

The aim of the study was to assess the potential application of teleradiology in the neonatal intensive care unit (NICU) by ascertaining whether any decrease in conspicuity of anatomic detail or interventional devices in the chest radiographs of premature infants is caused by picture archiving and communication system (PACS)-based soft copy interpretation of 10 : 1 compressed images. One hundred digital chest radiographs of low-birthweight infants were obtained in the NICU using a storage phosphor system. Laser-printed images were interpreted and the data set for each radiograph was then irreversibly compressed by a 10 : 1 ratio. Four radiologists with extensive PACS experience used a five-point grading system to score laser-printed hard copy images for the visibility of six parameters of anatomic landmarks and interventional devices in the chest. Compressed soft copy images displayed on 2K PACS workstation were subsequently scored using the same approach. Statistical manipulation demonstrated no loss of anatomic detail in five of the six parameters scored, with minimal difference in one landmark, the retrocardiac lung assessment. While further study is required to assess the clinical impact of the variance noted when evaluating lung parameters, the preservation or improvement of information in the remaining parameters following irreversible compression and soft copy interpretation is promising for the potential use of teleradiology in this population.     

Design of Distributed Interactive Online Geographic Information System Viewer using Wavelets

The purpose of this work is to develop a distributed interactive online geographic information system (DIO-GIS) viewer using wavelet theory. Wavelet analysis is a new mathematical tool that transforms information into a multiresolution format. This allows efficient transmission of data upon clients’ requests. In DIO-GIS, a raster map is treated as a 2D function and decomposed into a nonredundant hierarchy of submaps by storing only the differences between the various resolutions. These differences in scale can be compressed, transmitted separately over the Internet, and then reconstructed up to the desired resolution by the client. A prototype DIO-GIS viewer is implemented using a wavelet scheme known as lifting to achieve a pure integer transform. This prototype demonstrates that the described approach can achieve similar compression to JPEG while providing a hierarchical decomposition of maps, which makes it very efficient in transferring large amounts of GIS data over low-speed networks. In particular, by coupling the compression algorithms with the ability to perform zooming and panning operations over networks, this prototype is able to eliminate redundant data transfer and achieve a smooth real-time image-browsing capability. This distinguishes it from other networked GIS browsers, which work with standard image file formats such as GIF and JPEG.     

Digital imaging of black and white photomicrographs: impact of file size

The publication of black and white photomicrographs has a long tradition in pathology. High-resolution film and quality objectives have been the backbone of generating quality photomicrographs suitable for publication. However, the digital imaging revolution has changed the way we view and capture images. As the quality of image capture devices increases and as their price decreases, more and more investigators are using digital imaging, and the use of color digital imaging for teleconferencing, telediagnosis, and reproduction is now well established. The purpose of this study was to determine the file sizes needed to obtain publication-quality black and white images using digital imaging technology. In this study, four experts in renal pathology reviewed 70 black and white images of various file sizes obtained from specimens representing a variety of renal histopathology. Without knowledge of the file size, the four renal pathologists graded the degree of pixelation, and the overall diagnostic and publication quality of the images. In all cases, digital imaging was capable of obtaining publication quality images equal to those achieved using film. The file size needed to achieve publication quality black and white images depended on magnification, with lower magnification images requiring larger file sizes.     

Unusual case of biclonal gammopathy of undetermined significance]

OBJECTIVE: This was a pilot teleradiology project connecting two secondary KwaZulu-Natal hospitals' radiography departments to a central Durban teaching hospital. The purpose of the study was to assess the usefulness of same-day teleradiology reports to the medical staff and whether such a service changed patient management. DESIGN: After 1 month's service at each hospital, the first 200 teleradiology reports, original radiographs and patients' case notes were reviewed to determine whether any errors in interpretation of the radiographs had been made and whether the reports had changed patient management. RESULTS: The service changed patient management in 10% of cases. Undetected pathology was recognised by the radiologist in 20 patients--pulmonary tuberculosis in 10, spinal tuberculosis in 3, miliary tuberculosis in 2 and fractures in 5. Problems were encountered with transmission of data using the current telephone network, loss of data at the receiving station and the increased workload of the radiographer transmitting the data. CONCLUSIONS: Teleradiology services do make a positive impact on patient management in rural hospitals. However, there are many technical pitfalls that must be avoided in order to establish an effective service.     

Digital images in the diagnosis of wound healing problems

The use of digital wound images could allow remote consultation among patients, physicians, or other care-givers located at quite distant sites by means of the Internet. To evaluate the efficacy and validity of digital images for the evaluation of wounds, the ability and reliability of surgeons to diagnose and make treatment suggestions using digital images of several types of wounds were compared. Twenty-four wound images on 35-mm slides were selected for use in this study. Each slide image was digitized at 24-bit color with a resolution of 640 pixels horizontal by 425 pixels vertical and stored as a JPEG file. These images were then presented as a slide show on a video monitor, with resolution set at 640 x 480. Six physicians examined the images, first in digital format and later in the original slide form. Each observer assessed each wound and possible treatment options by filling out a questionnaire using a series of yes/no questions. For all observers, there was an 87 percent agreement between digital and slide images (p = 0.004). The agreement between the digital and slide images was measured for each individual observer using a kappa coefficient. The agreement level corresponded to the experience of the observer, with the kappa values ranging from greater than 0.8 (almost perfect agreement) for the attending plastic surgeon to just greater than 0.5 (moderate agreement) for the intern. With this study, the feasibility of distance wound consultation using digital images of a quality consistent with consumer-grade digital photography was demonstrated.     

Influence of neuronal excitation and inhibition of rostral ventrolateral medulla on the effect of electroacupuncture of "Neiguan" acupoint]

OBJECTIVES: To evaluate observers' use of image-enhancement facilities and time consumption in assessing caries in radiographs taken with four digital systems. METHODS: In total, 131 extracted human premolars and molars were mounted three in a line. Radiographs were taken using four digital systems: Digora (DIG), Radio VisioGraphy (RVG), Sens-A-Ray (SAR) and Visualix (VIX), and imported into a programme with routines for adjustment of brightness, contrast and gamma curve. Sixteen images from each digital system were compressed (JPEG, irreversible compression). The 588 images were scored by six observers for approximal and occlusal caries on a five-point confidence scale using enhancement as they pleased. The programme automatically recorded any enhancement made without the observers knowing this. RESULTS: Some form of digital enhancement was used in almost all images, with the gamma curve being the most frequent. The VIX images were enhanced most followed by SAR, DIG and RVG images. The differences were significant (p < 0.01) except between DIG and SAR images. The compressed images were enhanced significantly more than their uncompressed counterparts (p = 0.02). The average time spent recording one image was 24 s. On average, significantly less time was spent with the DIG images than the other systems (p < 0.01), while there were no significant differences between the CCD-based systems (p > 0.2). There was no relationship between time spent and number of manipulations performed. CONCLUSIONS: The observers took advantage of the facilities available for enhancement of density and contrast in digital images. The potential of gamma curve manipulation requires further investigation.     

The mouse chromosome 7 distal imprinting domain maps to G-bands F4/F5

RATIONALE AND OBJECTIVES: The authors designed, assembled, tested, and clinically evaluated a high-quality, fast, and relatively inexpensive telemammography system. METHODS: The authors designed a telemammography system that uses a high-resolution film digitizer and high data compression (> or = 40:1) to send images over regular telephone lines to a high-resolution laser printer that produces images with the look and feel of the original image and can operate in a hub and spokes mode. The authors then evaluated the system's performance. In a preliminary clinical study, interpretations of the laser-printed system's output of 119 cases were compared with the original interpretations, followed by a review of any clinically significant differences. RESULTS: With the exception of the laser printer, which is a modified off-the-shelf product, all hardware components of the system are commercially available products. The system digitizes (50 microns pixel size), compresses, transmits, receives, decompresses, and prints a 30 MB mammography file in less than 4 minutes. In the clinical study, there were 13 differences (in 13 cases) in the level of concern or recommendations. Seven were found to be clinically insignificant by a third-party review. The remaining six were reviewed by the original interpreter, and three were determined to be significant enough for further action. All were found to result from intra-reader variability rather than differences in visualization of possible abnormalities. CONCLUSIONS: Almost real-time, high-quality telemammography without geographic boundaries is possible with the use of high-level data compression. Telemammography with laser-printed film as the display may make it possible to offer mammographic services in remote locations while using commercially available technology.     

Teleradiology in rural imaging centres

An economic analysis of a private commercial magnetic resonance (MR) imaging service was carried out. At an expected case-load of 2000 per year, a mid-field MR unit was predicted to cost $470 per case using teleradiology and $544 per case using film and a courier service. Routine and emergency MR services were provided to two communities in Maryland. In a two-year study period, 8083 teleradiology examinations were performed. Digital images were acquired and transmitted without data compression via ISDN at 128 kbit/s to a central diagnostic workstation for interpretation by a team of radiologists. The average transmission time for a typical case of 50 images was 6-8 min. Preliminary interpretations were normally available within 2 h and the final transcribed reports were usually faxed to the physicians' offices within 24 h. The results of a survey indicated that the system was well received by both referring physicians and patients. Costs per case in practice were similar to those predicted.     

Three-dimensional echocardiographic planimetry of maximal regurgitant orifice area in myxomatous mitral regurgitation: intraoperative comparison with proximal flow convergence

The purpose of this study was to evaluate the usefulness of multishot echo-planar imaging in detecting liver tumors in comparison with respiratory triggered T2-weighted fast-spin-echo (FSE) imaging. Thirty-two patients with 70 focal liver lesions were imaged using a 1.5-T high speed MR imager. Eight-shot echo-planar images covering the whole liver were acquired during a single breath-hold period. FSE images were acquired with respiratory triggering in approximately 4 minutes. Lesion detectability and image quality of the two pulse sequences were analyzed qualitatively. Quantitative analysis was performed by means of signal-to-noise and tumor-liver contrast-to-noise analysis. Lesion detectability was comparable in both solid (86.3% vs 90.2%: .3 < P < .5) and nonsolid lesions (89.5% vs 100%: .3 < P < .5) between echo-planar and FSE images. Echo-planar imaging provided significantly reduced image artifact, better lesion conspicuity, and anatomic detail compared with FSE imaging. The signal-to-noise and contrast-to-noise ratios of echo-planar images were significantly higher than those of FSE images. Breath-hold eight-shot echo-planar imaging can be an alternative to T2-weighted FSE imaging because it can provide comparable image quality in a substantially decreased acquisition time.     

A remote conference system for image diagnosis on the World-Wide Web

OBJECTIVE: The World-Wide Web on the Internet enables an exchange of multimedia information among remote desktop computers. Therefore, a teleradiology system using the Web would allow remote consultation with expert radiologists. Our objective was to establish a Web-based prototype system for image interpretation. CONCLUSION: Our system allows a physician to transmit clinically useful images to an expert radiologist at a different location, who can see them on a Web browser and discuss diagnoses with the physician.     

Support by telecommunication of decisions in diagnostic pathology. Experience with the first telepathology system in Hungary

The term of telepathology can be determined as diagnostic work of the pathologist at distance via an interactive telecommunication connection in which the image of the specimen appears on a monitor instead of viewing it directly through a microscope. Being a part of the telemedicine, the fast development of the telepathology is based on the revolution of the new digital technology. Technical advances of telecommunication and of image procession in the latest 80s have provided the means to transfer huge amount of visual information in narrow communication bandwidth in two direction link. In 1995 multiple live image transmission with simultaneous voice transfer has been performed between the Department of Pathology of MI Central Hospital and 1.st Institute of Pathology and Experimental Cancer Research of Semmelweis Medical University, Budapest. Transfer rate via ISDN channel was 128 kbit/sec. The first live image telemedicine system in CCE/NIS countries has achieved transmission of cytological smears, frozen sections and paraffin embedded slides supplemented with immunohistochemical preparations. Quality of visual information using video-conference software of standard H.320 was suitable for diagnosis. Development of global telepathology services depends on compatibility of different systems and on comprehensive examinations of cost, accessibility and quality for the clients and providers of telemedicine. Recent paper surveys shortly the historical development of the telepathology, analyses the essence of the new consultation technology, summaries the first experiences in Hungary and raises some questions have to be answered in the near future.