Effect of ISDN bandwidth on image quality for telemedicine transmission of obstetric ultrasonography.

Objective: To evaluate objectively the effect of different bandwidths on the ability to interpret obstetric ultrasound scans transmitted live over a commercial telephone network.

Materials and methods: An integrated services digital network (ISDN) was established from three satellite offices to our central prenatal diagnostic center. In the first half of the study, the network was based on four ISDN channels transmitting at a bandwidth of 256 kbits per second (kbps), while in the second half of the study, this was increased to six ISDN channels transmitting at 384 kbps. A physician trained in obstetric ultrasonography provided an interpretation of fetal anatomy using a live, real-time telemedicine link. A scoring system consisting of 33 anatomic items was used to evaluate image quality objectively. The number of transmissions complicated by motion artifact was also recorded.

Results: One hundred patients had a fetal anatomy survey performed using the 256 kbps system, and these interpretations were compared with those from another group of 100 patients who were examined using the 384 kbps system. Although the visibility of the 33 anatomic items was similar using the two systems, significantly more examinations at 256 kbps were complicated by motion artifact (12% vs. 3%; P = 0.02).

Conclusions: Remote sonographic viewing of fetal anatomy was adequate using both 256 and 384 kbps systems, although motion artifact was significantly more likely to occur using the slower system. This problem may affect the ability of the lower-bandwidth system to allow optimal detection when fetal anomalies are present.