PubMed Health⌕ Search

Biomedical subjects

J N Stahl

Publications and source records attributed to J N Stahl.

6 recordsLinked to original sources
PubMed2000

Network latency and operator performance in teleradiology applications.

Teleradiology applications often use an interactive conferencing mode with remote control mouse pointers. When a telephone is used for voice communication, latencies of the data network can create a temporal discrepancy between the position of the mouse pointer and the verbal communication. To assess the effects of this dissociation, we examined the performance of 5 test persons carrying out simple teleradiology tasks under varying simulated network conditions. When the network latency exceeded 400 milliseconds, the performance of the test persons dropped, and an increasing number of errors were made. This effect was the same for constant latencies, which can occur on the network path, and for variable delays caused by the Nagle algorithm, an internal buffering scheme used by the TCP/IP protocol. Because the Nagle algorithm used in typical TCP/IP implementations causes a latency of about 300 milliseconds even before a data packet is sent, any additional latency in the network of 100 milliseconds or more will result in a decreased operator performance in teleradiology applications. These conditions frequently occur on the public Internet or on overseas connections. For optimal performance, the authors recommend bypassing the Nagle algorithm in teleradiology applications.

Algorithms↗
PubMed2000

Teleconferencing with dynamic medical images.

Dynamic images, a sequence of static images displayed in rapid succession and perceived as a continuous motion by the human eye, are widely used in medicine. One of the primary objectives of telemedicine is the transmission of such images to a distant location to manage clinical problems remotely. A broad variety of methods is available to acquire, store, transmit, and display these images. However, the context of the clinical problem determines which of these methods can be deployed in a telemedicine solution. This paper discusses the advantages and disadvantages of the different technologies and presents an example of a teleconferencing system for interventional cardiology. This system acquires cardiac angiography and intravascular ultrasound images and transmits them over an existing Internet connection to a distant location. It is specifically optimized for clinical conferencing, where time is limited for each case presentation during the conference, compared to the relatively long time available for the conference preparation. The system takes advantage of this characteristic by transmitting the images well in advance of the clinical conference and displaying them synchronously in both locations during the conference. This allows for the preservation of the original image quality.

Blood Vessels↗
PubMed2000

Real-time teleconsultation with high-resolution and large-volume medical images for collaborative healthcare.

Real-time consultation between referring physicians or radiologists with an expert is critical for timely and adequate management of problem cases. During consultation, both sides need to: 1) synchronously manipulate high-resolution digital radiographic images or large volume MR/CT images; 2) perform interpretation interactively; and 3) converse with audio. We present a specifically designed teleconsultation system in a digital imaging and communication in medicine picture archiving and communication systems clinical environment. The system uses bidirectional remote control technology to meet critical teleconsultation application requirements with high-resolution and large-volume medical images operated in a limited-bandwidth network setting. We give the system design and implementation methods, and also describe the teleconsultation procedure and protocol used in this system. Finally, laboratory and clinical evaluation results are discussed.

Delivery of Health Care↗
PubMedDate not supplied

Customized medical image databases: a low-cost approach.

The increasing use of digital images in medicine creates a demand for efficient but simple methods to store, retrieve and display images. The ideal solution for this might be a large-scale hospital-integrated picture archiving and communication systems, but this is not applicable under all conditions. A small-scale, user-defined image database running on a desktop computer may fit the individual needs better, while yielding optimal cost-effectiveness. We will present a way to create customized image databases using a general-purpose desktop database system and a specialized, dedicated image handling component programmed in C++.

Cost-Benefit Analysis↗
PubMedDate not supplied

A new approach to teleconferencing with intravascular US and cardiac angiography in a low-bandwidth environment.

A common problem in radiology teleconferencing is the difficulty of transmitting a large volume of data over communication channels with a relatively low bandwidth. Although videoconferencing systems are easily implemented, they generally require lossy image compression, which can lead to significantly altered findings. A teleconsultation and teleconferencing system was developed that uses a store-and-forward approach with high-quality dynamic medical images obtained with intravascular ultrasonography and cardiac angiography. The system allows use of high-resolution dynamic images while preserving their original quality and can be adapted to different clinical applications with varying requirements. The system involves a standard preparation procedure to transmit images from one location to another prior to a conference; once the conference starts, however, the system becomes fully automatic and synchronizes the display and manipulation of images in both locations without further image data transmission. In general radiologic applications, the system is superior to videoconferencing systems in that it does not require specialized hardware and dedicated high-bandwidth communication links. Further investigation with large-scale studies will be required to determine whether these benefits can lead to more widespread acceptance of such a system in routine clinical practice and whether teleconferencing itself can enhance the effectiveness of clinical procedures.

Coronary Angiography↗