DICOM (and other open standards) hold the promise of universal interoperability between disparate imaging systems. DICOM promises to allow veterinary radiologists to open any image, from any vendor, in any DICOM viewer. In theory, this is correct and DICOM works this way 99.9% of the time. Unfortunately, there are a few cases where DICOM implementations do not work out as planned and images will not open in some DICOM viewers.
One of the issues we often encounter in working with DICOM images is the inconsistency of image data. This is a recurrent issue with ultrasound systems, and very old CR/DR systems. Although DICOM is a standard and dictates how an image should be created and stored, it doesn’t’ always give the programmers enough details on what is “expected” vs. what is acceptable. This results in what we like to refer to as “DICOM Compliant” vs “DICOM Compatible” images. A compatible image will open in any image viewer providing that the pixel data in the image is accessible and decodable according to the standard. A compliant image is an image that is structurally correct, and even DICOM legal, but has an oddity about it that make it decode, or display differently in different viewers. This oddity is often a uncommon programming choice that a vendor implemented. Although this programming option is "legal" by DICOM standards, it may not be supported by all viewers.
Pointing fingers when we encounter images that will not open in all viewers does little good. The truth is that everyone is at fault, the programmer that decided to use an usual implementation, the PACS system that didn’t account for that issue, and the viewers that don’t support all formats that would account for these outlier structures.
At DVMInsight we incorporate a significant amount of fixes to help correct for outliers and try to give a consistent experience to all the clients and readers. We work closely with a DICOM library developer and have provided hundreds of images to them that fall into these fringe areas so they can be incorporated into the DVMinsight platform. Unfortunately, on occasion we still encounter issues with images and images will not open in all DICOM viewers. Although this happens very uncommonly, this is an unavoidable hassle to radiologists using the DVMinsight platform.
Our basic testing of images from vendors that are new the the DVMinsight PLATFORM uses four viewers. Efilm, Clear Canvas (www.clearcanvas.ca), Osirix, and OFFIS (Adobe). If an image will open in all four viewers we know that radiologists will have no problem with the images. When we encounter an image issue we spend time trying to locate why each viewer is having difficulties and then decide how to “work around” the issue.
To give you an example of what goes on behind the scenes, consider this analogy. DICOM is a language. All languages have nuances, new words, and old words that your grandparents may use but you might not be familiar with. For example, if someone asked you for a "hundredweight*" of maltodextrin. You would probably ask why anyone* would want that much malto and then ask what a hundredweight is. The reply might be that a hundredweight is "eight stone." In this example, these weights are a perfectly good use of the English language but you might not understand them because you are not familiar with those words. The same thing goes with DICOM and DICOM viewers. There are images that are perfectly DICOM compliant but some viewers wont be able to open them because they are not familiar with that particular piece of DICOM.
Getting back to the real world, the following example is a bit technical but we know of no other way to discuss these types of issues. One issue we encounter is the inability of images to display once they have been compressed into different formats. Recently we’ve begun to encounter US images and OT images that use an odd structure. These images are perfectly DICOM compliant, but not a compatible as it could be. The images render as a mish-mash of colored bands and static. However, when these same images are saved in .51,.57 JPEG encoding they display perfectly in three of the four viewers. Unfortunately, a popular viewer among veterinary radiologists, eFilm, will not render these images properly and generate an error about "JPG not recognized."
Despite our best efforts at DVMinsight at building workarounds and the efforts of the Animal Insides DICOM validation, vendors will continue to use outlier encoding in their images. Because veterinary radiologists do not get to pick where their images come from, a very easy approach to dealing with these outlier images is to simply utilize 2 DICOM viewers in day to day practice. Fortunately on both the Mac and PC platform there are free DICOM viewers that can be used as primary or alternate viewers. Clear Canvas http://www.clearcanvas.ca/ is a fully featured viewer for the PC that many radiologists use as their primary viewer. It even includes MPR support. Osirix is a fully featured viewer for the Mac that nearly all Mac fanatics use as their primary viewer http://www.osirix-viewer.com/
Bottom line; veterinary radiologists must be able to receive images from numerous different systems. Every once in a while we can expect to encounter images that will not open in all DICOM viewers. The easiest and most efficient workaround for this is to use two DICOM viewers in day to day practice. Open source viewers for the PC and Mac are available for situations when images will not open in a primary viewer such as eFilm.
___________________________________
*A hundredweight is 112 pounds.
**Maltodextrin is a polysaccharide that is used as a food additive. It is produced from starch by partial hydrolysis and is usually found as a creamy-white hygroscopic spraydried powder. Maltodextrin is easily digestible, being absorbed as rapidly as glucose, and might be either moderately sweet or almost flavorless. It is commonly used for the production of natural sodas and candy and sports drinks. Stop paying out the nose for your sports drinks. Source your malto direct!