Volumetric navigation tackles image overload but introduces new challenges

June 6, 2005

While the rapid transition to multislice CT overloads radiologists with images, the typical workflow strategy used to cope with image overload is unsatisfactory, according to a SCAR University session. A volumetric navigation approach addresses this problem, but not without problems of its own.

While the rapid transition to multislice CT overloads radiologists with images, the typical workflow strategy used to cope with image overload is unsatisfactory, according to a SCAR University session. A volumetric navigation approach addresses this problem, but not without problems of its own.

Dr. Eliot Siegel, vice chair of information systems at the University of Maryland School of Medicine, described the most common strategy radiologists use to cope with CT image overload: acquire images using thin collimation and then reconstruct the ones sent to PACS using thicker sections (5 or 8 mm).

This method results in up to a 10-fold reduction in the number of images sent to PACS. Technologists can then perform additional reconstructions using a dedicated CT workstation.

"This approach requires a large amount of technologists' time, especially for angiographic rendering, analogous to the extra time required for technologists to produce films in multiple window/level settings," Siegel said.

The reconstructed images also unnecessarily take up a good deal of archival, network, and workstation memory, he said.

"Radiologists should have flexibility from case to case to determine whether images should be reviewed in sagittal, coronal, or oblique planes or using a 3D perspective," he said.

Volumetric navigation, which frees the radiologist from the limitations of fixed-slice axial images, is the alternative, according to Siegel.

"An image of the spine, for example, can be rapidly and interactively rendered and viewed as a sagittal or coronal data set at any desired slice thickness," he said.

Although volumetric navigation has great potential, however, it presents new challenges, introducing the possibility that image volume overload may be being traded for image content overload.

"Our abdominal and thoracic subspecialists are asking whether they are responsible for detailed reports of the musculoskeletal, spine, and vascular systems now visualized on routine body CT studies," Siegel said.

They ask if they should specifically and routinely comment on the renal arteries, aortic and iliac arteries, and superior and inferior mesenteric arteries. If so, what are the implications of this responsibility on the time required to dictate a study?

Another barrier to volumetric navigation is its lack of integration with current PACS workstations.

"It is not practical for a radiologist interpreting a study using a PACS workstation to walk over to a dedicated 3D/multiplanar workstation for each case," Siegel said.