We have reached a point where the hardware and software of handheld computing platforms are powerful and mature enough to be leveraged in Pathology, including the use of WSI-based applications. Therefore, it is reasonable to expect that there will be increasingly more articles in the future regarding pathology and handhelds. Since half of the existing literature already deals with telepathology applications, we can anticipate more research in this area of digital imaging. Many factors require further enhancements including optimal resolution, pixel density, and improved technology for display of WSI, as well as greater attention devoted to patient security and regulations regarding mobile computing in healthcare.
Map/navigation applications on handhelds (e.g., Google Maps, Microsoft Bing Maps) behave in a manner extremely similar to WSI: usage of massive pyramidal images broken up into tiles that are served on a real-time basis to the viewer. There have been efforts to use the publically available map application programming interfaces (API) from Google and Microsoft to create WSI viewers for educational use,[82
] and it is only a matter of time before this work is replicated on handhelds. The multitouch and voice recognition user interface paradigms likewise bear further exploration, especially on larger form factors like tablets.
At least two major problems exist when considering the use of WSI on a smartphone. One problem is that smartphone screens are, by design, are small. The small physical size is intrinsic to the role of a smartphone, and therefore not a limitation that will disappear as technology evolves. Large screen size, however, is valuable for viewing and interpreting a whole-slide image. One plausible solution would be to create smartphones in which the screen can be expanded if needed, and then shrunk back for normal use. Work on creating flexible LCD screens has been in progress at many places in the past decade. A good example of the current state of the art is the prototype by Sony that was announced in 2010.[83
] This screen is thin and flexible enough to be rolled around a pencil. If smartphones with such expandable screens were to become widely available, they would solve the problem of small screen size for WSI.
An alternative solution would be for a smartphone user to leverage a nearby large screen by borrowing it for temporary use. Large LCD screens are a consumer item today, and available in large volumes at relatively low prices. The challenge is to develop a workflow and associated software that allows use of nearby displays from smartphones in a manner that respects HIPAA-compliant data privacy and at the same time offers a viable business model. Initial experimental steps toward such a capability were described by Wolbach et al
, in 2008.[84
] Here is a motivating scenario verbatim from that paper:
Dr. Jone is at a restaurant with his family. He is contacted during dinner by his senior resident, who is having difficulty interpreting a pathology slide. Although Dr. Jones could download and view a low-resolution version of the pathology slide on his smart phone, it would be a fruitless exercise because of the tiny screen. Fortunately, the restaurant has a large display with an Internet-connected computer near the entrance. It is sometimes used by customers who are waiting for tables; at other times it displays advertising. Using Kimberley, Dr. Jones is able to temporarily install a whole-slide image viewer, download the 100 MB pathology slide from a secure web site, and view the slide at full resolution on the large display. He chooses to view privacy-sensitive information about the patient on his smart phone rather than the large display. He quickly sees the source of the resident's difficulty, helps him resolve the issue over the phone, and then returns to dinner with his family.
A second problem that impedes universal viewing of WSI from smartphones is the vendor specificity of data formats. Each scanner manufacturer typically uses a different, proprietary format for its whole-slide images. Software that can interpret this proprietary format is a lucrative line of business for the manufacturer. Unfortunately, the marketplace fragmentation induced by these proprietary formats complicates efforts to create universal software for remote viewing of whole-slide images from smartphones. As a step toward solving this problem, a vendor-neutral open-source software library for WSI called OpenSlide has been created.[85
] Reading whole-slide images using standard tools or libraries is a challenge because these are typically designed for images that fit into memory when uncompressed. Whole-slide images routinely exceed memory sizes, often occupying tens of gigabytes when uncompressed. The design of OpenSlide is structured similar to the device driver model found in operating systems. Application-facing code is linked to vendor-specific code by way of internal constructors and function pointers. Recently, OpenSlide has been extended to support remote viewing over the Internet. The implementation is in the form of Python bindings for the OpenSeaDragon viewer.[86
] This framework-agnostic AJAX-based Deep-Zoom viewer is derived from the code that was released open source by Microsoft as part of its ASP.NET AJAX Control Toolkit in September 2009.[87
] Example whole-slide images at the OpenSlide demo site[88
] can be viewed today over a 3G network on a smartphone browser.
Due to the fact that handheld web browsers are now identical to those being deployed on desktop PCs, any advance in the usage of Web 2.0 technologies in pathology will directly apply to handhelds. Furthermore, smartphones and tablets now integrate both Wi-Fi connectivity and relational DBMS′s, raising the possibility of their use as both servers and clients for full-fledged LIS and EMRs, especially in developing countries and during times of catastrophe. Tablets provide a form factor and size similar to that of printed books, raising the possibility of their unique use in pathology education. In developing countries, for instance, a tablet with preloaded educational content could be made to function as a webserver, streaming that content to a learning community that would otherwise not have those resources.