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 liv e over a commercial telephone network. Materials and Methods: An integ rated services digital network (ISDN) was established from three satel lite offices to our central prenatal diagnostic center. In the first h alf of the study, the network was based on four ISDN channels transmit ting at a bandwidth of 256 kbits per second (kbps), while in the secon d half of the study, this was increased to six ISDN channels transmitt ing at 384 kbps. A physician trained in obstetric ultrasonography prov ided an interpretation of fetal anatomy using a live, real-time teleme dicine link. A scoring system consisting of 33 anatomic items was used to evaluate image quality objectively. The number of transmissions co mplicated by motion artifact was also recorded. Results: One hundred p atients had a fetal anatomy survey performed using the 256 kbps system , and these interpretations were compared with those from another grou p of 100 patients who were examined using the 384 kbps system. Althoug h the visibility of the 33 anatomic items was similar using the two sy stems, significantly more examinations at 256 kbps were complicated by motion artifact (12% vs. 3%; P = 0.02). Conclusions: Remote sonograph ic viewing of fetal anatomy was adequate using both 256 and 384 kbps s ystems, although motion artifact was significantly more likely to occu r using the slower system. This problem may affect the ability of the lower-bandwidth system to allow optimal detection when fetal anomalies are present.