Complex applications must defer to system limitations

September 5, 2008

The advent of PACS has opened up a wealth of new ways to work with imaging data. Radiologists must be prepared to compromise, though, when seeking out practical solutions for daily use. If added sophistication means overcomplexity, then it may be time to think again, according to speakers at this year's European Congress of Radiology.

The advent of PACS has opened up a wealth of new ways to work with imaging data. Radiologists must be prepared to compromise, though, when seeking out practical solutions for daily use. If added sophistication means overcomplexity, then it may be time to think again, according to speakers at this year's European Congress of Radiology.

Radiologists' quest for the perfect postprocessing setup is a case in point. The ideal solution simply does not exist, Prof. Alain Blum told delegates at the ECR session: "What can PACS do today?"

Radiologists want to do their image reconstruction without moving from the PACS workstation, said Blum, a professor of radiology at the University Hospital of Nancy, France. In reality, however, the functionality offered by PACS workstations is not adequate for all clinical applications.

A PACS workstation should be able to display images acquired from different modalities and multiplanar reconstructions. This capability will be sufficient in around 80% of cases, Blum said. Dedicated postprocessing workstations may also have tools for bone and vessel extraction, virtual colonoscopy, tumor segmentation, 4D imaging, and/or cardiac analysis. So linking such a workstation to the PACS means the speed of image processing should be faster, and image quality may be better.

"Integration between a PACS workstation and a modality workstation is effective, but it is a very expensive way to provide all that you need," he said. "Radiologists have to be highly trained to use such a system."

An alternative option is to use the dedicated workstation together with a stand-alone PC running the RIS. This setup still offers many advantages in terms of speed and functionality, but it is not always appropriate for complex cases. The preferred solution may be to supplement the basic postprocessing tools available on the RIS/PACS workstation with advanced software provided by a 3D server.

"The functionality offered by the 3D server is almost equal"but not quite"to that of a dedicated modality workstation," Blum said. "This solution is cost-effective and avoids unnecessary transfer of images."

Compromises may also be required when using PACS to support radiological education. As Dr. Andoni Toms, a radiologist at the Norfolk and Norwich University Hospital in Norwich, U.K., explained, educators and end-users may sideline solutions that seem overly complex.

"It is very easy to say, 'I want the best of all worlds in all categories.' But it is probably better to look for simple solutions that everyone is going to use," Toms said.

The NNUH is one of three sites in the U.K. that has a dedicated radiology training academy. Cases stored on the hospital's PACS form an essential part of the residents' education.

The simplest, fastest approach to generating teaching material is to archive cases into different folders and subfolders on the PACS, Toms said. This strategy allows whole cases to be archived. Search functionality is limited, however, and trainees will have to hunt within folders for cases.

Another option is to use web-based archives such as www.myPACS.net. It takes a few minutes to download a case from PACS, annotate it, and then upload images into a folder in the web archive. One advantage is accessibility to cases made publicly available by other users. The downside is that each case will typically contain just a few images instead of the full series.

Another important issue is the anonymization of images used for teaching purposes. If cases are exported from PACS onto a CD or DVD, the patient's name can be stripped out easily and replaced with a unique identifier. Anonymizing images within PACS is considerably more complex. A solution has now been implemented at the NNUH, but cases must be pushed to another workstation and then pushed back into the PACS.

"The advantage is that you now have fully anonymous DICOM data sets on the PACS network. Not only can trainees access these, but so can anyone with a PACS login," he said.

The NNUH's training academy includes a program that allows residents to perform a virtual anatomical dissection and then correlate the findings with MR or CT images from PACS. The results can be projected onto a screen and shared.

-By Paula Gould