Prot?g? assists in RadLex development

Coming up with a standard radiology terminology is the seemingly Herculean task of RadLex, a lexicon for the uniform indexing and retrieval of radiology information resources. The effort formally began in 2005 with the formation of six committees formed in collaboration with more than 30 radiology professional and standards organizations.

In 2006, more than 7,500 terms were released and 2007 saw the addition of six additional committees, with each focusing on a specific imaging modality. Adoption of the terminologies is ongoing and significant, as its widespread deployment will allow the use of clinical information technology to analyze radiology reports using standard terms in a structured format. RadLex is available without charge through the Radiological Society of North America.

A team at Stanford University Medical Center in Palo Alto, Calif., has used an open-source application, Protégé, to assist RadLex developers in their management of terminologies through an ontological structure. The Stanford team, led by Daniel Rubin, MD, described their efforts in a study published online before print in the Journal of Digital Imaging.

Rubin, a clinical assistant professor of radiology at Stanford and scientific director of the National Center of Biomedical Ontology, noted that there have been three obstacles in the development and use of terminologies such as RadLex.

“RadLex is being acquired using text files and spreadsheets, formats that simplify the task of collecting terms by radiology experts,” he wrote. “However, these formats make it difficult to browse, manage, and modify the large RadLex hierarchy as it grows.”

In addition, maintaining and deploying the flat-file structure make it difficult to analyze and deploy, respectively.

Protégé is an open-source, free tool for creating and managing ontologies, as well as for developing applications that use them. The development team built the RadLex ontology by writing a software script that mapped the representational primitives in Protégé to those in the RadLex vocabulary.

“We provided our ontology and Protégé tool to the RadLex developers to evaluate for qualitative feedback on the usability of the tool and its suitability for browsing and managing RadLex,” the authors wrote.

The Stanford team noted that the RadLex developers reported that this format and display made the terminology easier for curators to manage than using the spreadsheet format, although content authors may still prefer a spreadsheet for acquiring new terms. The Protégé tool also has proven its usefulness as a debugger, allowing synonyms and duplicate terms to be discovered within RadLex.

The tool is now in use at the RadLex term browser, which allows users to search on the nearly 12,000 terms in the lexicon.   

“Our results suggest that vocabularies such as RadLex can be translated into an ontology and that this representation can permit computational analysis that can help curation efforts to identify omissions, inconsistencies, and redundancies in the terminology,” the authors wrote.