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 .
 background : telepathology practice across international borders has become increasingly popular . 
 our telepathology consultation service with a laboratory in china was hampered by latency issues when viewing whole slide images.objective:the aim was to explore data transfer solutions to improve the viewing experience of digital consult cases.methods:whole slide image files residing on a server in china were transferred to our data center in the usa using an open source product ( fast data transfer ) . a faster more automated commercial high speed file transfer software solution ( aspera ) 
 was also tested.results:transferring files with the open source product provided transfer speeds of 23 mbps , but suffered from intermittent dropped connections . employing commercial software permitted more reliable transmission of digital files with 
 75100 mbps transfer speeds.conclusions:successful global telepathology requires dedicated image management . 
 transfer of files to local servers by employing high speed data transfer tools helped overcome network latency issues , improved the overall turn - around time of digital consultations , and enhanced the viewing experience for end - user digital consultants . 
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