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Results


Figure 6 A
 
Figure 6 B


Figure 6 C

Figure 6 : Example ultrasound images collected during the tele-operated examination. The images show (A) the computer screen at the expert center with the video image of the patient site (left) and the ultrasound of the hepatic vein Doppler, (B) a view of a kidney, and (C) colour Doppler view of a carotid stenosis. 
Over a five month period, 100 teleoperated ultrasound examinations were conducted in the 2 small medical centers 50-60km away from the University Hospital, on the abdomen and pelvis (36%), vascular structures (42%), and other small parts including the thyroid and various skin muscles disease (22%).

All examinations were standardized to include imaging and measurements of similar organs and structures. The abdominal examination included B-mode visualization of the pancreas, liver, biliary tract, gall bladder, and the right and left kidneys (Figure 6A and 6B). Pelvic examinations involved the visualization of the bladder, uterus and ovaries, or prostate. Vascular imaging included assessments of the carotid arteries or the veins of the lower limbs. The common carotid artery was imaged in B-mode for the measurement of the intima-media thickness and the bifurcation was imaged in B-mode, colour, and PW Doppler modes for the calculations of the resistance index and the quantification of stenosis (Figure 6C). The veins of the lower leg (femoral, popliteal, posterior tibial, and gastrocnemius veins) were imaged in B-mode and colour Doppler with compression being applied to the leg distal from the Doppler recording point. Thyroid investigations included transverse and longitudinal views in B-mode, colour, and PW Doppler modes and muscle examinations included the visualization of the muscle and vascular structures with both B-mode and colour.

Organs were adequately visualized, the colour and PW Doppler correctly displayed, and the diagnosis given for 97% of the examinations. In two obese patients the pancreas and gall bladder could not be visualized due to poor echogenicity. In an additional patient, edema and fat tissue prevented the proper imaging of the leg deep veins. In each of these cases the patient underwent a conventional echography examination at a radiology center.

Setup of the connections for teleoperation and the videoconference required less than 3 minutes. Each examination took an average of 17±4 minutes to complete. Using the Internet connection for teleoperation (1Mbits/s; 10 frame/s), there was about a two second lag for commands to be transmitted to the echograph and motorized probe and for the resulting modifications in the ultrasound video to be transmitted back to the expert site. The sonographer was able to accommodate for this lag after about one hour of training with the system. Additionally, the quality of the ultrasound image at the expert site was slightly lower than that on the actual echograph at the patient site; however, the images were still of good quality for medical diagnoses. On two occasions the teleoperated examination could not be performed due to a low Internet connection greatly degrading the quality of the transmitted video. Therefore, these exams were rescheduled for the following day without issue.

The teleoperated examinations performed with 15 pregnant patients in long distance sites (hospital in Ceuta n=10, and hospital in French Guyana n=5) reported similar quality of ultrasound images allowing for medical diagnoses. There was no difference in the teleoperation lag with the hospital in Ceuta using ground Internet, but the delay was increased to three seconds for examinations conducted in French Guyana (7000km from the expert sonographer) using satellite Internet. Limited testing was also conducted with the expert sonographer located away from the University Hospital (20 out of the 100 cases with the medical center) using home, mobile phone, airport, or hotel Internet connections with no detriments to the teleoperation of the echograph and probe system.

Discussion

The current study successfully demonstrated the clinical use of the teleoperated integrated echograph and probe system for performing clinical ultrasound examinations in areas isolated from trained sonographers. This system improved upon previously used methods of remote ultrasound examinations to provide a system that is smaller and easier to use for the non-sonographer operator, does not require substantial training of the non-sonographer operator, allows for the teleoperation of the echograph by the trained sonographer, and utilizes a standard Internet connection. The results of this study demonstrate that this teleoperated echograph and probe system may be used in clinical setting where a trained sonographer is not readily available.

 

Conclusion

The current teleoperated echograph and probe system allowed for ultrasound examinations to be performed quickly (15-20min), successfully (in 97% of the cases), and without the need of a trained operator at the patient site. This system serves to reduce the time required for patients to receive medical diagnoses, potentially resulting in faster initiation of treatment and improved patient outcomes. The teleoperated echograph and probe unit in the current study, “TOURS”, is a substantial improvement on the previous version requiring the use of a large, heavy robotic arm and support structure. The echograph and probe system is light (Echograph 6kg; electrical module and computer 1.3kg), and the motorized probes (430g and 300g) do not require a large support structure making it ideal for location with environmental constraints (geographically isolated sites, centers with limited medical equipment, long distance airplanes, hazardous areas, spaceflight, etc.). Currently, this system is scheduled to fly onboard the International Space Station at the end 2016 under the project name TOURS (Tele-Operated UltRasound in Space). 
 

Acknowledgments : The authors thank Mme. Maryannick. Porcher for her active contribution to the tele-echography examinations.

Grant Support : The present work was supported by CNES (French Space Agency), R & T grant: TOURS-2:131512-2014.

Disclosure : No conflicts of interest are declared by the authors.