Taming the Torrent of Multislice Images

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Multislice CT scanners have become the core of the 21st century radiology department. Sixteen-slice scanners took the market by storm just a few years ago, proving their utility in a wide range of applications and becoming the new bread and butter of many radiology departments and imaging centers. The market has been equally welcoming to their 64-slice siblings, which offer improved speed and image resolution to make cardiac CT a reality. But no matter how the situation is sliced, these powerhorses present a major workflow challenge. That's because 64-slice scans can entail several thousand images; per image image size may be a hefty 0.5 megabyte. This mega-data is produced faster than ever before. Scan times have fallen to just a few seconds, but CIOs and department heads need to think long and hard to guarantee instant image access.

Healthcare facilities have employed a variety of mechanisms to master the multislice beast. First on the list may be changing reading protocols. "It's not feasible to trudge through 1,500 images axially," points out W. Daryle Heath, CT supervisor at St. Dominic Jackson Memorial Hospital in Jackson, Miss. Radiologists need to embrace a paradigm shift. "We aren't dealing with slices anymore. Sub-millimeter thick slices [are not meant to be examined individually]. They are sections of data that lead to clinically relevant images via post-processing. We need to move away from the term 'slice' and think about computerized volumetric imaging. CT has become more analogous to MR angiography with a volumetric acquisition and interrogation," explains Jay Cinnamon, MD, neuroradiologist and director of 3D imaging at Quantum Radiology Northwest in Marietta, Ga.

Many sites rely on highly trained techs for 3D scanning and post-processing. Quantum Radiology has employed a 3D lab model; specialized techs complete the lion's share of post-processing in a central area. Results are promising. CT angiogram post-processing that required an arduous 45 minutes to an hour two years ago has now been cut to a very reasonable 10 minutes.

And technology, in the form of dedicated 3D workstations and software or dedicated servers, can save the day as well. The ultimate technical solution will be a truly integrated 3D PACS model, predicts Matthew Barish, MD, director of 3D imaging processing center at Brigham and Women's Hospital in Boston. In this model, the PACS permanently stores thin-slice data for 3D reconstruction at any time in the future. This model requires easily accessible 3D hanging protocols and tools.

Ultimately, streamlined multislice workflow depends on a delicate balance between technology and organizational management. "Staff can learn the 'buttonology' to master new scanners and workstations, but organizational management is a big gap," says Cinnamon. In other words, facilities must determine processes and protocols that tame the multislice beast, allowing them to reap the full clinical gains without sacrificing workflow.

Moving into the future, CAD will play a larger role in CT workflow as new CAD software and reading paradigms help reduce the multislice workflow burden for screening studies.

Inside the 3D lab

Quantum Radiology Northwest typifies the busy outpatient imaging practice. It is equipped with more than a dozen CT scanners and serves three area hospitals. The CT portfolio includes a newly installed Philips Medical Systems Brilliance CT 40-slice scanner, three 16-slice scanners and Philips and Vital Images multimodality workstations. The practice plans to add a 64-slice scanner in 2006.

"Radiologists are viewing forty 4,000-slice studies each day," offers Cinnamon. "[Many] require post-processing. Practices have to deal with workflow. A centralized 3D post-processing lab is the way to go." Many advanced studies made possible by higher-slice scanners such as CT angiograms and lung nodule assessments require a post-processing step.

Quantum Radiology keeps post-processing time to a minimum by relying on specially trained techs to complete the bulk of the post-processing. The radiologist completes the post-processing, reviews and dictates the case. "It's like a relay race with the tech handing a baton to the radiologist. The challenge is that the baton hand-off occurs at different points for different applications," explains Cinnamon.

Take for example a neurovascular CT angiogram. The tech completes 90 percent of the work including processing, measuring, filming and uploading to PACS. The radiologist