global digital pathology networks between pathology laboratories , academic centers and commercial entities have capitalized on whole slide imaging ( wsi ) technology , the internet and cloud services . at the university of pittsburgh medical center ( upmc ) we launched a telepathology consultation service with kingmed diagnostics laboratory in guangzhou , china . wsi submitted for consultation resided on the client 's server ( hammamatsu ndp.serve ) in china . pathology consultants from pittsburgh in the usa used the web portal to securely access these images on the client 's server . workflow ( e.g. , case triage and transcription ) and reporting was incorporated into this web - based application . with the aforementioned information technology client - specific infrastructure , we were able to initially avoid lengthy transfers of large wsi files over the internet . however , after 2 years of practice network latency issues increased that negatively impacted viewing of wsis and hence interpretation of digital consultation cases . reasons for the delay in processing network data were often hard to determine and , therefore , resolve . ping tools identified decreased download and upload speeds for connections to servers in china compared with those located locally . although the current telepathology workload is manageable , the delays experienced by pathologists ( lengthy time waiting for images to open , pixelated images when panning and zooming ) were frustrating . therefore , the aim of our study was to explore various image file transfer solutions to improve the viewing experience of digital consult cases . to solve ongoing latency issues , two attempts were made to transfer wsi files from china to an image server at upmc in our data center . the first solution employed an open source product ( fast data transfer [ fdt ] , by cern . a command line utility was established to facilitate a batch transfer process of image files [ figure 1 ] . aspera uses user datagram protocol ( udp ) , does not involve data compression , and permitted immediate file transfers that did not need to be initiated by a user [ figure 2 ] . the aspera software was configured using a  hot folder  for automated file transfer . with this set up , every time a file was dropped into the folder on the server in china it was immediately transferred over to the upmc server . since aspera can be configured to take up as much of the sender 's bandwidth network pipe as needed , our team set it up to use 80 mbps of the client 's 100 mbps internet connection to transfer files off business hours . once images were successfully transferred to the usa , when consultants logged into the web - based portal to access their digital pathology cases they were offered the option to view digital slides launched either from the server in china or locally in pittsburgh . process steps involved using an open source tool to transfer images process steps involved using aspera to transfer images table 1 compares file sizes , transfer times , and image quality parameters for the two transfer methods used . transferring files with the open source product fdt provided fast transfer speeds of 23 mbps , but suffered from intermittent dropped connections . although these interruptions varied throughout the day , they were most marked at 6 am in pittsburgh ( eastern time zone ) . the image transfers with fdt required 515 min of extra processing time to zip files and involved a batch process . it was also noted that the open source zip utility did not compress files much more than they were already being compressed by the nanozoomer scanner ( nanozoomer 2.0-ht , hamamatsu ) . employing the commercial file transfer software , aspera permitted much faster ( 75100 mbps ) transfer speeds . use of hot folders did not add any extra processing time to the transfers and avoided files having to sit in a queue . in addition , the file sizes being transferred with fdt were larger because the open source software zipped up multiple images ( anywhere from 10 to 30 files ) into one file , whereas aspera sent over one image file at a time . fdt was used to transfer 8 cases ( 101 slides ) including hematopathology and breast / gynecologic consults . all of these cases comprised large specimens that contained anywhere from 8 - 15 slides , except for 1 biopsy that included 2 slides . the open source software file sizes represent multiple whole slide images batched together , whereas only one file at a time was transmitted with the commercial software successful global telepathology requires dedicated image management , which includes fast and reliable movement of digital data . traditional transmission of data over the internet can be slow due to congestion , degradation , erratic transfer speed , and bottlenecks ( e.g. , packet loss ) . attempts in radiology to improve data transmission time between medical imaging systems have been based mainly on image compression . according to the american telemedicine association ( ata ) clinical guidelines for telepathology , compression technology may be applied with telepathology so long as it does not compromise the image for clinical use . the guidelines state that reversible ( lossless ) compression may always be used as there is no impact on the image . however , irreversible ( lossy ) compression may be used to reduce transmission time or storage space only if the resulting quality is sufficient to reliably perform the clinical task . fortunately , prior studies have shown that image compression does not appear to noticeably affect image quality and diagnostic accuracy , at least for store - and - forward telepathology . use of compression methods to improve data transmission time may not always be effective in high - speed networks . newer transmission methods and bulk data transport tools , such as aspera , which use alternative technology ( e.g. udp - based application - level protocols vs. traditional tcp - based transport ) offer innovative solutions . for example , some investigators were able to improve radiology image transmission time by using parallelism ( increased number of parallel network streams ) without compression . it is important to be aware , however , that overwhelming a network with too many streams may cause congestion and therefore actually have a negative effect on throughput achieved . despite the fact that transferring files from china to our local server delayed the availability of images for consultants to view by up to 24 h , this measure improved the overall turn - around time of digital consultations because pathologists found it easier to work with locally stored wsis . although we resolved the latency issue impacting our consulting pathologists , the exact reason causing this latency has not been clarified . network latency is not limited to file transfers between china and the usa , but can be an issue anywhere in the world , even within the usa . although biological materials ( slides and blocks with human tissue ) can not leave china to be sent to our institution , we are not aware of any regulations restricting the movement of images out of china . it is unclear how our telepathology experience was impacted by the golden shield project ( i.e. great firewall of china ) , which is china 's censorship of the internet . using a combination of firewalls and proxy servers at internet gateways china are able to analyze and manipulate internet traffic . nonetheless , transfer of digital files helped us overcome network latency issues , which in turn enhanced the viewing experience for end - user digital consultants .