Digital Pulse - Chap 3 - Sec 4 - Queensland Ultrasound Project

Development Issues: Telemedicine, Prenatal Health

Programme Summary

Many communities in Queensland are remote, with little, if any, timely access to specialized services. Ultrasound is an accepted method of diagnosis and assessment of foetal anomalies, but the quality of the service varies widely between tertiary and peripheral units. Telemedicine offers the opportunity for real-time specialist referral, with reductions in anxiety for delayed referral, disruption to family life, and travel costs.

The Centre for Online Health is a research, teaching, education and service provider within the University of Queensland's Faculty of Health Sciences. The Centre's mission is: “To pursue improvements in health care through the application of information technology.”

The Centre has four areas of activity:

• A focus on research in the area of online health
• Teaching about online health
• Commercialisation of research outcomes, and
• The delivery of services in online health.

Summary of ICT Initiatives

Current real-time telemedicine relies on digital (ISDN) lines and hence is costly and still limited to larger centres. If the Internet could be used as a method of downloading ultrasound images taken in the field quickly and effectively, this would bring tertiary consultation to even extremely remote centres, using just a portable ultrasound machine with digitised images, a laptop computer and modem. The minimum acceptable standard for digital compression of an ultrasound video clip had not been assessed before.

In 2001, a study by the Centre of Online Health was conducted to assess the ability of examiners to make accurate diagnoses based on compressed ultrasound clips of foetal anomalies, as well as their confidence in making such diagnoses. Prior to this project, the minimum acceptable standard for digital compression of an ultrasound video clip had not been assessed before. An application such as this is a boon to remote communities that have little, if any, timely access to specialized services. The aim of this project was to assess the ability of the examiners to make accurate diagnoses based on compressed ultrasound clips of foetal anomalies, as well as their confidence in making such diagnoses. This project was completed in 2001.

Observations

Evaluation methods involved nine different clips of foetal anomalies and two different normal controls that were compressed using commercially available software. The original uncompressed file sizes ranged from 55.6 to 622.7MB. Final file sizes ranged from 1.6 to 10MB (that is, compression ratios of 1:10 – 1:130). The duration of each original video clip ranged from 30 seconds to 3 minutes. The cardiac clips included colour and Power Doppler sequences, increasing the file size. Five of the normal control clips were repeated, to allow evaluation of intra observer error.

Four experienced tertiary ultrasound specialists blinded to the compression factor evaluated the images. The examiners were asked to make a diagnosis from a selection of 48 possible choices. They were then asked to rate their confidence in the diagnosis (based on the quality of transmission) and image clarity on a scale of 1-7, with a score of 1 being very uncertain, 4 being acceptable and 7 being very certain. Data was analyzed using Duncan's multiple range test for variables, with alpha=0.05.

All of the diagnoses were responded to with certainty from the four observers on raw mean scores. The cardiac anomalies tended to rate with lower certainty scores. All of the images were rated as acceptable (mean greater than 4.00) for image clarity and assessment of anatomy. Intra- and inter-rater error was not significant.

The conclusion was that video clips of foetal ultrasound can be digitised, compressed and displayed on the computer without clinically or statistically significant loss of diagnostic certainty or image clarity. More specifically, this study examined compressing clips to 5 or 10MB file sizes and displaying them at a frame rate of 15 frames per second and a screen size of 320 x 240 pixels. With these specifications, diagnosis of 9 foetal anomalies was successful and image clarity was maintained for certainty of diagnosis. Original file sizes up to 622.7MB (equivalent to clips from 30 seconds up to 3 minutes duration, depending on content) may be compressed with commercially available packages to file sizes as small as 1.6MB, or compression ratios from1:10 to 1:130. This has importance for applications such as telemedicine, and picture archiving for medico-legal and teaching purposes.

Partners: University of Queensland

Source: Centre for Online Health Resources and Project websites.

For More Information Contact:

St. Lucia Office

Centre for Online Health

Lvl 3, General Purpose South

The University of Queensland

St. Lucia QLD 4072

Australia

Voice: +61 (07) 3365 4671 or 3346 4754

Fax: +61 (07) 3346 4705

enquiries@coh.uq.edu.au