CT and MRI get new DICOM data sets to help volume overload

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After more than a decade of use and with the immense growth in the volume of CT and MRI studies, it's time for a new DICOM standard -- which was outlined by Bradley Erickson, MD, PhD, of Mayo Clinic, and David Clunie, MBBS, chief technology officer of RadPharm, on June 3rd at the Society for Computer Applications in Radiology (SCAR) Annual Meeting in Orlando, Fla.
Erickson and Clunie detailed several common problems radiologists face as they manipulate CT and MRI images and how new standards remedy the problems.
   
"Important data elements like diffusion, perfusion and new CT scanning modes aren't standard across vendors. Nor do images process or display well across all vendor workstations," says Erickson. Furthermore, the series numbers PACS use to hang studies do not necessarily reflect practice.
   
Enhanced DICOM objects address the problem by including many more standard mandatory attributes and terms and by allowing multiple frames in a single object. "This enables greater interoperability, more effective hanging protocols and less dependence on private attributes," states Clunie. The richer set of mandatory descriptive attributes will facilitate downstream display of images on various workstations.
   
New objects include the presence or absence of contrast to make it easy to distinguish contrast use. Mandatory coded anatomic regions and laterality will improve hanging protocols.
   
Erickson listed several CT DICOM problems. Multi-phase CT images appear different on different PACS and it can be difficult to fuse PET and CT studies from different vendors.
   
New objects support advanced applications, facilitating visualization, temporal changes and quantitative and analytic applications. For example, new CT objects cover attenuation, table speed, reconstruction and other parameters. The addition of color by functional paradigm facilitates specific applications like functional MRI (fMRI) .
   
Original DICOM posed other problems as well, says Erickson. Radiologists can not reprocess data from older studies as scanner technology advances because PACS does not save raw data. MR spectroscopy is not supported in early versions of DICOM.
   
The new version includes raw data classes to store images in PACS, so that they can be regurgitated for reconstruction later. And DICOM now supports storage of spectroscopy data.
   
A final problem addressed by the new DICOM is the immense network burden of new multislice CT scanners. New multi-frame objects don't change common headers; information isn't replicated and latency between storage requests is reduced. There is an opportunity for 3D compression. Theoretical gains in raw network transfer of 275 megabyte CTA on a gigabyte Ethernet network showed a 30 percent increase with more significant gains likely in practice using the multi-frame approach.
   
A host of vendors-Agfa, Dynamic Imaging, GE Healthcare, Hitachi Medical Systems, INFINITT, jMRUI, McKesson Medical Imaging, Philips Medical Systems, Siemens Medical Solutions and Toshiba America Medical Systems-demonstrated the new objects at SCAR. MRI and CT test tools and image development are available now. Users can begin to take advantage of the new objects by asking vendors about the release of products supporting the new features.
   
As for other modalities, the Society for Nuclear Medicine will release a first draft outlining the need for a new multi-frame PET object at its June meeting. A draft letter ballot will address the need for objects for new x-ray angiography applications later this month.