Assessment of the quality of neonatal echocardiographic images transmitted by ISDN telephone lines

Abstract

Objective: To assess the quality of echocardiographic images from neonates transmitted over Integrated Service Digital Network 2 (ISDN2) channels.

Design: Echocardiographic images were viewed live in real time either by a direct video link or by transmission over the commercial network, using one, two, or three ISDN2 channels. The order of the viewing formats was random and four observers marked each view for potential for provision of complete diagnostic information and quality.

Setting: Cardiology department of tertiary referral centre for paediatric cardiac services. ISDN lines were positioned in two nearby rooms. Telephone connection was through the commercial network and video connection by a direct video cable.

Patients: 10 neonates were studied (weight 2600 to 3900 g). In each, nine echocardiographic studies were undertaken to assess imaging (M mode and cross sectional) and Doppler (spectral and colour) quality.

Results: No significant differences were found in diagnostic ability between the different formats for M mode, colour, or spectral Doppler studies. For cross sectional imaging the diagnostic information and image quality increased with increasing numbers of ISDN channels. With six channels there was little difference from the directly connected images.

Conclusions: In echocardiographic assessment of the newborn, one or two ISDN2 channels will transmit images of satisfactory quality in many situations but three or more channels are necessary to ensure minimum degradation of the live image.

Figure 1

The percentage of images considered to be non-diagnostic for each echocardiography technique and each transmission mode.

Figure 2

Image quality analysis of colour flow Doppler images transmitted over one, two, and three channel ISDN2 lines.

Figure 3

Combined percentage scores of all four cross sectional echocardiographic views.