Objective: The purpose of this study was to demonstrate the first use of voice-grade telephone lines for the international transmission of both high-resolution digital images (radiology and pathology) and video in near real-time.
Materials and methods: Eight live demonstrations were performed from the United Arab Emirates and the Kingdom of Saudi Arabia at the invitation of the respective ministries of health. Thirty radiologic studies (CT, MR, and radiographs) were digitized, compressed, and transmitted to Cambridge, MA, where they were interpreted on diagnostic workstations (1792 x 2252 display matrix) by a team of subspecialist radiologists. Near real-time image transmission was achieved by combining wavelet-based image compression (average compression ratio of 23:1) and multiplexing technology that used four phone lines simultaneously. During each demonstration, one pathology image was transmitted from Cambridge to the demonstration site, where it was interpreted by a visiting pathologist. Video-conferencing was implemented with a 64-kilobits-per-sec leased line from the United Arab Emirates and with four multiplexed telephone lines from Saudi Arabia.
Results: For teleradiology and telepathology, transmission times ranged from 2-5 min per image. Image fidelity was judged to be of diagnostic quality in all transmitted cases. The video link to the United Arab Emirates was highly reliable. Bandwidth for videoconferencing from Saudi Arabia was marginal on four voice-grade telephone lines, resulting in some downtime (10-20%). Live consultations provided by subspecialists in Cambridge assisted in the management of patients at both venues. The system was well received by both the referring physicians in the Middle East and the participants in the United States.
Conclusion: Image compression and multiplexing technologies enabled high-resolution teleradiology and telepathology as well as real-time video consultations over international telephone lines. While telecommunications systems are advancing rapidly in many parts of the world, those areas most in need of telemedicine services are likely to be the last to upgrade their telecommunications infrastructures. This "proof of concept" article outlines a practical and affordable approach that makes telemedicine more accessible to underserved areas worldwide.