Tele-Endoscopy: Influence of Data Compression, Bandwidth and Simulated Impairments on the Usability of Real-Time Digital Video Endoscopy Transmissions for Medical Diagnoses

Background and Study Aims: Real-time digital video transmission (rtDVT) at an acceptable quality through networks has been possible for several years. This technique can be used for telemedical applications, such as tele-endoscopy. The hypotheses of the present study were that the quality of real-time DVT depends on the technical equipment used, and that the resulting image quality influences the usability of the system for diagnostic purposes.
Materials and Methods: An experimental network was established between two German referral endoscopy centers, using the Asynchronous Transfer Mode (ATM) protocol. At first, rtDVTs of routine gastrointestinal video endoscopies were transferred through the network for prospective evaluation of the feasibility of the technical equipment and its usability for diagnostic tele-endoscopy, based on the video image quality. Secondly, the image quality and usability for correct telemedical diagnosis were evaluated prospectively in a double-blind experimental setting in relation to variations in the methods of data compression used, transmission bandwidths, and simulated transmission errors. Fourteen endoscopists evaluated 27 variations of an endoscopic video sequence.
Results: Compression with the Moving Picture Expert Group 2 (MPEG2 [4 : 2 : 2]) standard, the ATM protocol, and a bandwidth of 40 megabits per second (Mb/s) were used successfully in 40 routine tele-endoscopies for practical evaluation. Doctors were able to handle the system with ease, and its availability was 100 %. There were no detectable differences between the original video image and the transferred image, and the images were usable for diagnosis in all cases. The set-up used clinically was therefore considered to provide the optimal conditions for comparisons in the experimental part of the study. Experimentally, any technical variation was found to cause a reduction in the overall image quality and hence a reduction in diagnostic usability: compression algorithm (MPEG2 [4 : 2 : 2] vs. others: P = 0.001), bandwidth (≥ 8 vs. < 8 Mb/s: P = 0.001), and error rate (10^-8 vs. 10^-7: P = 0.001).
Conclusions: rtDVT using MPEG2 [4 : 2 : 2] compression and a bandwidth of 40 Mb/s did not effectively differ from the original video images in routine tele-endoscopy. The qualitative requirements in diagnostic video endoscopy, however, are obviously much higher than previously assumed, since experienced endoscopists detected a loss of image quality and a reduction in diagnostic usability with any reduction in the technical specification. Modern methods of data compression, broadband networks and a network protocol with good quality-of-service guarantees are therefore prerequisites for diagnostic rtDVT.

References

• 1 Telemedicine: Fad or future?.  Lancet. 1995;  345 73-74
• 2 Moore G T, Willemain T R, Bonanno R. et al . Comparison of television and telephone for remote medical consultation.  N Engl J Med. 1975;  292 729-732
• 3 Wootton R, Bloomer S E, Corbett R. et al . Multicentre randomised control trial comparing real time teledermatology with conventional outpatient dermatological care: Societal cost-benefit analysis.  Br Med J. 2000;  320 1252-1256
• 4 Arunachalam S. Informatics in clinical practice in developing countries: Still early days.  Br Med J. 1999;  319 1297-1302
• 5 Kim C Y. Compression of color medical images in gastrointestinal endoscopy: A review.  Medinfo. 1998;  9 1046-1050
• 6 Moses P L, McGowan J J, Ricci M A. Efficacy of tele-endoscopy in a rural capitated market.  J Am Med Inform Assn. 1997;  (Suppl. S) Yearbook 398-402
• 7 Kim C Y, Etemad B, Glenn T F. et al . Remote clinical assessment of gastrointestinal endoscopy (tele-endoscopy): An initial experience.  J Am Med Inform Assn. 2000;  (Suppl. S) Yearbook 423-427
• 8 Kraus B, Tarhanjan A, Keymling J. et al .Multimedia telecollaboration for second opinion in endoscopy. In: Brender J, editor Medical Informatics Europe 1996. Amsterdam; IOS Press 1996 Yearbook: 715-718
• 9 Mair F, Whitten P. Systematic review of studies of patient satisfaction with telemedicine.  Br Med J. 2000;  320 1517-1520
• 10 Wootton R. Telemedicine: A cautious welcome.  Br Med J. 1996;  313 1375-1377
• 11 Wyatt J C. Telemedicine trials: Clinical pull or technology push?.  Br Med J. 1996;  313 1380-1381
• 12 Murdoch I. Telemedicine.  Br J Ophthalmol. 1999;  83 1254-1256
• 13 Fraser H S, McGrath S J. Information technology and telemedicine in sub-Saharan Africa.  Br Med J. 2000;  321 465-466
• 14 Hilgers U, Naegele-Jackson S, Holleczek P, Hofmann R. Bereitstellung von Dienstgüte in IP- und ATM-Netzen als Voraussetzung für die Video-Übertragung mit Hardware Codecs. In: von Knop J, Haverkamp W, editors Innovative Anwendungen in Kommunikationsnetzen/15. DFN-Arbeitstagung über Kommunikationsnetze in Düsseldorf (6. bis 8. Juni). Bonn, Germany: Gesellschaft für Informatik. 2001: 63-71, (GI-Edition: Lecture Notes in Informatics; Proceedings, vol. 9.)
• 15 Naegele-Jackson S, Hilgers U, Holleczek P. Evaluation of codec behavior in IP and ATM networks. In: von Knop J, Schirmbacher P, editors Proceedings of the 7th International Conference of European University Information Systems, Berlin, Humboldt University, 2001, March 28 - 30 (EUNIS 2001). Berlin; Humboldt University 2001: (http://edoc.huberlin.de/abstract.php3?id = 3 000 576&lang = eng).
• 16 Naegele-Jackson S, Graeve M, Holleczek P. Spontaneity and delay considerations in distributed TV productions. In: von Knop J, Schirmbacher P, editors Proceedings of the 7th International Conference of European University Information Systems, Berlin, Humboldt University, 2001, March 28 - 30 (EUNIS 2001). Berlin; Humboldt University 2001: (http://edoc.huberlin.de/abstract.php3?id = 3 000 581&lang = eng).
• 17 Lambert R, Rey J F. Endoscopy and early neoplasia: Better but not the best.  Endoscopy. 2001;  33 348-352
• 18 Inoue H. Treatment of esophageal and gastric tumors.  Endoscopy. 2001;  33 119-125
• 19 Maiss J, Hahn E G, Hochberger J. Endoscopic treatment in early gastric cancer. In: Tandon R, Bhutani MS, editors Advances in interventional endoscopy. New Delhi; Jaypee Brothers 2001: 118-130
• 20 Ell C, May A, Gossner L. et al . Endoscopic mucosal resection of early cancer and high-grade dysplasia in Barrett’s esophagus.  Gastroenterology. 2000;  118 670-677
• 21 Balbach T, Sussmann H, Jansen T. et al . Teleconsultation for endoscopic diagnosis of gastrointestinal diseases: Concepts and architecture of the service ENDOTEL.  Stud Health Technol Inform. 1999;  68 234-237