Edward G. Grant

Clinical experience with sonographic contrast agents

Early generations of sonographic contrast agents are beginning to reach the attention of the clinician. Research and development of ultrasound contrast agents is progressing at a rapid pace with several new agents approaching US Food and Drug Administration approval. Cardiac imaging has been affected by even the limited availability of contrast agents on the market today both with regard to diagnosis of shunts and chamber opacification, and most recently actual enhancement of the myocardium. Later generations of contrast are capable of providing consistent opacification of both peripheral veins and arteries, and should prove useful in a variety clinical applications. Thus far, it appears that longer vessel segments may be seen with contrast rather than without contrast, and that flow may be demonstrated in vessels which were not seen or thought to be occluded with conventional color imaging. Improved detection of arterial and venous collaterals and enhanced identification of run-off vessels is demonstrated with sonographic contrast agents. An improved ability to evaluate renal artery stenosis and subtotal occlusion of the carotid artery are specific advantages of using contrast as well. Several compounds are currently being tested that may allow routine parenchymal opacification. Ultrasound is the most commonly performed diagnostic imaging procedure; therefore, contrast agents have the potential to dramatically alter the practice of clinical medicine. This article reviews the current status of ultrasound contrast agents and speculates regarding the future applications of these agents.

Ultrafast networks (ATM): First clinical experiences

Ultrafast networks using asynchronous transfer mode (ATM) technology can provide the bandwidth and throughput that may be sufficient to satisfy the medical imaging community. Several trials are underway to assess the effect of ATM network capabilities on the clinical practice of radiology, by providing immediate interactive radiology consultations between subspecialists and general radiologists at affiliated academic institutions. The hardware to build such networks is now commercially available and its cost is decreasing steadily, but the monthly charges for ATM bandwidth use are still high. Nevertheless, given the tremendous increase in communication capability and data transfer rates possible with ATM networks, cost alone should not be the determining factor for selecting this technology. The ATM concept in general is first reviewed, followed by a description of early clinical ATM network installation in four medical environments worldwide. These medical clusters include: the UCLA affiliated hospitals (UCLA Medical Center, West LA VAMC and Olive-View UCLA Medical Center), the UCSF affiliated hospitals, Duke University Hospitals and a cluster of medical centers in Berlin which have all been connected via ATM networks. The use of ATM technology in these realistic clinical environments is discussed and evaluated for its potential impact on patient care and clinical teaching within radiology departments. From this preliminary study it is concluded that image communications over a regional PACS using an ATM network can allow interactive consultations between different subspecialist and general radiologists or other specialized radiologists spread over different medical centers.

Assessment of ATM for transmission of medical images

The transmission of medical image data using asynchronous transfer mode (ATM) communication over a synchronous optical network (SONET) was evaluated. Key parameters and performance criteria of the ATM network were tested in order to assess the applicability of ATM technology to telemedicine. The ATM based network connection was provided by the local phone companies. The initial experiment involves two of three affiliated hospitals located within a 19 mile radius in California (the VA Medical Center, West Los Angeles; UCLA Medical Center; and Olive View-UCLA Medical Center). Each hospital has a picture archiving and communication system (PACS) within radiology. We designed an ATM over SONET network for PACS utilizing the TCP/IP communications protocol. We are implementing an ATM testbed over which we characterize the traffic and measure the total transmission time for large data files.

Evaluation and early medical experience with an ultrasound mini-PACS system at the VA Medical Center, West Los Angeles

The first development phase of a multi-modality Picture Archiving and Communications System (PACS) has been completed at the Veterans Affairs Medical Center West Los Angeles. This initial phase involved the development of an ultrasound mini-PACS system using a commercially available PACS product line (IMPAXTM) from AGFA Division of Miles Inc. The PACS provides acquisition, archival, display, and network printing capabilities.

Financial and workflow analysis of radiology reporting processes in the planning phase of implementation of a speech recognition system

The goal of this study is to determine the financial value and workflow improvements achievable by replacing traditional transcription services with a speech recognition system in a large, university hospital setting. Workflow metrics were measured at two hospitals, one of which exclusively uses a transcription service (UCLA Medical Center), and the other which exclusively uses speech recognition (West Los Angeles VA Hospital). Workflow metrics include time spent per report (the sum of time spent interpreting, dictating, reviewing, and editing), transcription turnaround, and total report turnaround. Compared to traditional transcription, speech recognition resulted in radiologists spending 13-32% more time per report, but it also resulted in reduction of report turnaround time by 22-62% and reduction of marginal cost per report by 94%. The model developed here helps justify the introduction of a speech recognition system by showing that the benefits of reduced operating costs and decreased turnaround time outweigh the cost of increased time spent per report. Whether the ultimate goal is to achieve a financial objective or to improve operational efficiency, it is important to conduct a thorough analysis of workflow before implementation.

Impact of ultrasound video transfer on the practice of ultrasound

Sonography can be highly dependent on real-time imaging and as such is highly physician intensive. Such situations arise mostly during complicated ultrasound radiology studies or echocardiology examinations. Under those circumstances it would be of benefit to transmit real-time images beyond the immediate area of the ultrasound laboratory when a physician is not on location. We undertook this study to determine if both static and dynamic image transfer to remote locations might be accomplished using an ultrafast ATM network and PACS. Image management of the local image files was performed by a commercial PACS from AGFA corporation. The local network was Ethernet based, and the global network was based on Asynchronous Transfer Mode (ATM, rates up to 100 Mbits/sec). Real-time image transfer involved two teaching hospitals, one of which had 2 separate ultrasound facilities. Radiologists consulted with technologists via telephone while the examinations were being performed. The applications of ATM network providing real time video for ultrasound imaging in a clinical environment and its potential impact on health delivery and clinical teaching. This technology increased technologist and physician productivity due to the elimination of commute time for physicians and waiting time for technologists and patients. Physician confidence in diagnosis increased compared to reviewing static images alone. This system provided instant access for radiologists to real-time scans from remote sites. Image quality and frame rate were equivalent to the original. The system increased productivity by allowing physicians to monitor studies at multiple sites simultaneously.

First six months of clinical usage of an ATM network link between two Veterans Affairs Medical Centers

Purpose/Background: Asynchronous transfer mode (ATM) network technology has recently been used for high speed transmission of radiological images between hospitals and inside hospitals. However, the number of clinical sites which routinely use this technology is limited. The purpose of this study was to analyze the very early impact of an ATM link between a large tertiary referral center and small peripheral clinic on cost and clinical practice. Methodology: An ATM link using 155 bps (OC3) technology was installed between the West Los Angeles VA Medical Center and the Sepulveda VA, a large outpatient facility which provides full service radiological services. The West Los Angeles VA Medical Center is a large tertiary referral center with sub-specialist radiologist. The clinical impact of this ATM link between a large full-scale DICOM-3 compliant PACS system at the West LA VA on a smaller PACS system at the Sepulveda VA was evaluated. Results: The ability to freely exchange complicated MRI and CT studies between a tertiary referral center and a clinic could have a direct impact on patient care. Over the last six months, all and CT studies from Sepulveda VA were readily available via the ATM connection to all radiologists at the West LA VA. On average the workload at the Sepulveda VA in CT and MRI was about one tenth of the same workload at West LA VA, thus creating interesting possibilities for sharing or radiologist resources. Conclusions: Although our preliminary data and work loads have been too limited to draw any final conclusions yet, we feel that future results will show that the ability to provide immediate and fast interactive consultation between general radiologists in a large outpatient facility and sub- specialists at a tertiary referral center can have an impact upon the quality of patient care.

Vascular Imaging with Sonographic Contrast Agents

Contrast agents are used extensively in vascular imaging and are an essential part of most radiographic examinations such as angiography, computed tomography (CT) and magnetic resonance imaging (MRI). In general, contrast agents change a specific property of an organ with regard to its surrounding tissues thereby increasing the signal-to-noise ratio of blood and allowing improved imaging of a targeted vessel. The exact method by which this improved imaging is accomplished depends upon the type of examination being performed. With examinations such as upper gastrointestinal series, intravenous urography or CT scans, contrast is used to increase the density of a specific organ system or vessel relative to the surrounding tissues. Therefore, high molecular weight elements such as barium or iodine are ingested or injected into the body.

Integrating DICOM conformant imaging equipment with a PACS

Purpose/Background: As medical centers purchase commercial PACS to integrate with their imaging equipment, the fact that each component is often purchased at different times and with differing levels of DICOM conformance may become a problem. When the PACS is installed, major incompatibilities are often discovered between DICOM conformant pieces of equipment. Commercial PACS vendors are sometimes reluctant to take responsibility for the final integration of these components. The purpose of this paper is to document the nature and extent of these problem at one medical center, to report on how we are trying to solve them, and recommendations for the future. Methods: A large commercial PACS (IMPAXTM, Bayer Corporation, Agfa division) installed at the West Los Angeles VA medical Center was recently upgraded to be DICOM 3.0 conformant. Recently purchased DICOM conformant CT and MRI units and an older CT were already present. The problems in interfacing and integrating these imaging modalities with the upgraded DICOM-compliant PACS were investigated. Both software and hardware incompatibilities and human factors in bringing the different commercial vendors together were analyzed. Results: Major hardware and software incompatibilities were discovered. The use of DICOM-gateways is not always able to solve problems of incompatibility. The typical lag time between discovery of a problem and provision of a solution was 4 to 5 months. For more severe problems and also for a few of the lesser problems, resolution took over a year and is still ongoing. Repeated requests had to be made to the vendors to get together with us and solve these problems.