New standards to help with interoperability
Reporting in the radiology domain is the highest priority for 2007 for the Integrating Health Enterprise (IHE), said H. Solomon of GE Healthcare during his presentation, “Electronic Measurements, Electronic Reports: IHE, DICOM and HL7 CDA” on Sunday at RSNA 2006.

“DICOM was supposed to take care of the whole workflow and is doing well,” Solomon said, “but referring physicians often don’t have DICOM.”

DICOM Structured Reporting (SR) was added to the standard in 1999 and provided the capability for integration of reporting with imaging, but its adoption has been limited because reporting functions have remained in information systems based primarily on HL7 standards. Since referring physicians commonly use systems with HL7 rather than DICOM capabilities, DICOM and HL7 working groups recognized the need to work together to define a standard methods for reporting that meet the needs of the real worlds. The process began in 2003 with elaboration of use cases for varying types and purposes of diagnostic reporting. Standards solutions were considered against these use cases, gaps identified and closed through extensions to the standards. Imaging results documents were classified as evidence documents or reports. The former include ultrasound measurements, cath lab structured reports, CAD results, etc., that are created in the imaging systems context. Evidence documents, together with images, are part of the information that a radiologist uses to produce a report.

DICOM standards of documents in the imaging environment have five clinical characteristics: persistence, stewardship, potential for authentication, wholeness and human readability. DICOM SR emphasizes coded semantic content while HL7 CDA emphasizes human readable text through simple XML style sheets.

SR and CDA were developed simultaneously and are congruent in document persistence, identification and relation to the patient and authoring physician, said Solomon. The IHE initiated an industry-wide effort to make it all work together through a standards-based approach to integration. “Now we have to develop workflows through IHE,” he said. When considering workflow, we need to remember that reporting starts before the radiologist sees images, with such reporting as the reason for the exam, technical aspects of the procedure, and post-processing results.

CDA implementation guides are now coming out, Solomon said. Some are coming from HL7 and some from IHE for emergency department referral, scanned documents, personal health records, etc. CDA release 2 was published in 2005 and all needed standards are now in place. Additions to DICOM in 2005 allow inclusion of CDA reports on DICOM removable disks and define communication of simple image references and annotation from PACS to reporting systems without requiring close integration of the two systems. Additions to CDA in 2006 include a common message element type (CMET) for imaging references. Standards now available provide practical and unambiguous definitions for the roles of DICOM and HL7 standards at the reporting interface.

While neither CDA nor SR guarantee exact visual reproduction, DICOM now can encapsulate foreign documents. Solomon pointed out that PDFs do allow for exact reproduction and have a role as recording the presentation of electronic documents. Both CDA and SR support wrapping PDF with their standard header.

Work continues in this area. When asked about clinical and coding vocabularies, Solomon said that “for good, coded information we need good, coded vocabularies and lexicons. Work is underway. Getting the semantics of a term is very hard. Determining how the concepts fit and relate to other concepts is going to take time.”