Real-time transmission of full-motion echocardiography over a high-speed data network: impact of data rate and network quality of service.

UNLABELLED: With high-resolution network transmission required for telemedicine, education, and guided-image acquisition, the impact of errors and transmission rates on image quality needs evaluation. METHODS: We transmitted clinical echocardiograms from 2 National Aeronautics and Space Administration (NASA) research centers with the use of Motion Picture Expert Group-2 (MPEG-2) encoding and asynchronous transmission mode (ATM) network protocol over the NASA Research and Education Network. Data rates and network quality (cell losses [CLR], errors [CER], and delay variability [CVD]) were altered and image quality was judged. RESULTS: At speeds of 3 to 5 megabits per second (Mbps), digital images were superior to those on videotape; at 2 Mbps, images were equivalent. Increasing CLR caused occasional, brief pauses. Extreme CER and CDV increases still yielded high-quality images. CONCLUSIONS: Real-time echocardiographic acquisition, guidance, and transmission is feasible with the use of MPEG-2 and ATM with broadcast quality seen above 3 Mbps, even with severe network quality degradation. These techniques can be applied to telemedicine and used for planned echocardiography aboard the International Space Station.

Low doses of repetitive ultraviolet A induce morphologic changes in human skin.

Repetitive exposure of skin to sunlight is known to result in dermatoheliosis, characterized by photoaging and carcinogenesis. It has been demonstrated previously that relatively large amounts of ultraviolet (UV) A can produce photodamage and it is believed that UVB plays a major role in the induction of photodamage and photocarcinogenesis. The study reported here determines the cutaneous effects of minimal erythemal amounts of solar-simulated UV radiation as well as suberythemal and minimal erythemal doses of UVA. Previously non-sunexposed human skin was irradiated twice weekly for 24 weeks. Biopsies were obtained 12, 24 and 36 weeks after the initial irradiation and assessed for both epidermal and dermal alterations. Dermal elastic tissue content was measured via computerized image analysis. All UV treatment regimens produced observable epidermal and dermal changes. These alterations were observed after only 12 weeks of twice-weekly irradiation and were still evident 12 weeks after the final irradiation. Interestingly, UVA irradiation produced a decrease in elastic tissue content whereas solar-simulated UV produced a slight increase. Most notable were the changes produced by the suberythemal dose of UVA. Surprisingly, this relatively low UVA dose produced a reduction in elastic tissue content. The results of this investigation demonstrate that small amounts of UVA or solar-simulated UV are capable of producing cutaneous photodamage. These findings suggest that even suberythemal doses of repetitive UVA may lead to photoaging of the skin and that there is a need for daily broad spectrum UV protection.