Validation of an automatic tool for the assessment of image quality in digital tele-echocardiography

We investigated a novel tool for assessing image degradation in tele-echocardiography. Different video recordings from an echocardiographic examination were transmitted using commercial videoconferencing equipment via a local area network. Different compression schemes were selected, ranging from MPEG 1 to MPEG 4, with transmission at different bit rates ranging from 1.0 to 4.5 Mbit/s. Three methods were used to compare the transmitted and received video sequences: the peak signal to noise ratio, the Double Stimulus Impairment Scale (DSIS) and the National Telecommunication and Information Administration Virtual Quality Metric (VQM). The results showed that the most useful grading procedure was the subjective DSIS. There was a high correlation between the DSIS results and the VQM. The VQM could be thus an effective tool for evaluating tele-echocardiography transmission systems, avoiding the costs and times associated with conducting subjective tests in repeatable conditions.