Minimum technical requirements and evaluating effectiveness of teleradiology.

Teleradiology, the electronic transmission of radiological images for the purposes of interpretation and consultation, has successfully entered routine health services. It is, therefore, currently one of the single largest applications of telemedicine. This technology is predicted to play a significant role in improving service access to rural and remote areas. However, teleradiology services are currently characterized by a compromise between expense and quality of digital images. This paper reviews minimum equipment requirements and the technical issues and limits that are experienced when utilizing current teleradiological technology. Categories of service evaluation, including measures of user satisfaction, clinical outcome and financial benefit, are discussed in relation to facilitating a radiology service of the highest quality possible.

Staining PO2 measurement sites in the rat brain cortex and quantitative morphometry of the surrounding capillaries.

The exact positions of microelectrodes used to measure the PO2 in the cerebral cortex of the rat were determined by staining the tissue with Alcian Blue. The measurement sites were subsequently located under a light microscope and correlated with the capillary and cellular arrangement of the cortex. The microelectrodes used for the PO2 measurements were made of gold glass fibers; the Alcian Blue was injected hydrostatically through a micropipette attached to the PO2 microelectrode. The sites where dye had been deposited were seen under a light microscope as green blue spots about 100 micrometers in diameter. The capillaries were visualized by silver nitrate perfusion. Differences between the local PO2 values in the neo- and the archeocortex were found. In the neocortex the mean PO2 was 31 mm Hg, capillary volume 1.6%, capillary surface area 980/mm2, capillary length 13.5/mm; whereas in the archeocortex these values where 21 mm Hg, 0.9%, 820/mm2 and 9.4/mm respectively. These data indicate a relationship between the microcirculatory transport system and the local oxygen tension and provide further evidence that the mean PO2 level tends to decrease when moving from the surface into the archeocortex.

Staining of PO2 measuring points demonstrated for the rat brain cortex.

A combined physiological and histological technique was developed in order to determine the exact position of the tip of a microelectrode used for PO2 measurements within the rat brain cortex. Using this method it was possible both to identify the tissue layer where PO2 measurements had been performed as well as obtain information about the blood capillaries within the surrounding tissue. After the PO2 had been measured small quantities of dye (Alcian Blue 8 GX) were injected through a micropipette attached to the PO2 microelectrode (tip-tip distance 2-5 micron). Subsequently the tissue was fixed by perfusion, 5 micron sections were cut and stained with Cresylviolet. The points where measurements had been made could be seen under a light microscope as green coloured spots of about 100 micron in diameter. The capillary pattern could be demonstrated by silver nitrate perfusion. Information about the capillaries, such as length, distance and the gas exchange surface were obtained via computer analysis of a television image. This method was used to analyse the O2 supply of the optical cortex of the rat. Correlation of the local PO2 distribution with the capillary data revealed differences between the archi- and the neocortex of the rat brain.