Strategies to Enhance Volumetric CT & Workflow

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Multislice CT facilities are overcoming the workflow challenges and near image-overload issues with a variety of efforts before, during and after the study, including powerful protocols, workstations, post-processing techniques such as 3D and multiplanar reconstruction and PACS.

Computed tomography examinations have become the cornerstone of modern radiology departments as studies that historically were performed using other modalities have migrated to this domain with the development of high speed, multislice, volumetric CT scanners.

Michael Vannier, MD, professor of radiology at the University of Chicago Hospitals, explains that utilizing the most modern CT scanners, in the same amount of time or less, at similar levels of reimbursement, clinicians can acquire more images at a lower radiation dose with greater image quality. Two to three years ago, the typical CT study generated approximately 300 images per exam, but with 16-slice scanners, it is not unusual to have 1,000 to 3,000 images produced for a single patient study.

Improvements to the scanners bring higher quality images in significantly less time. Most clinicians do not just look at slices, but use post-processing techniques to produce 3D volumetric image data sets for standard exams to enhance diagnostic capability in routine studies.

"It's gone a step further with scanners that are so fast and capable that you can look at moving structures, including the heart," says Vannier. "Now you can look at the beating heart with the kind of detail that we're accustomed to seeing with CT." The clarity of images provided by CT may surpass the details provided by other imaging modalities without requiring invasive procedures in cardiac catheterization, for example.

Given today's fastest scanners, clinicians can visualize coronary arteries in action using only an intravenous injection of contrast rather than threading a catheter from the patient's groin to heart that often necessitates an overnight hospital stay. The industry has moved from 4, 6 and 8 slice scanners up to 16 and 32 slice machines to the latest incarnations of this equipment featuring 40 to 64 slices that are in the process of release at this time.


Scott Lipson, MD, associate director of imaging at Long Beach Memorial Medical Center in California, uses the Toshiba America Medical Systems Aquilion 16 multislice scanner for their busy CT angiography practice, that includes several CTA exams every day as well as orthopedic imaging, brain, sinuses, chest exams and many trauma cases as well. He says the only study they do not perform is CT colonography in this active center that is the second largest private hospital on the West Coast.

Lipson believes that the work they did "up front" in establishing automated protocols for studies has made their workflow extremely efficient. They established comprehensive protocols to inform the technicians about not only how to perform the study, but how to manage the data after they are acquired.

"When I tell the CT techs I want an abdomen pancreas [scan] or a CTA of the carotid arteries, they can pull up a protocol that has all of the information they would need," says Lipson. "It has acquisition parameters, coverage, how to set up the scan, what type of contrast to use, and then it has all of the information about how to reconstruct [the images], what thickness, what planes, and where to send the reconstructed information: to the PACS, to the workstation, or both. All of our protocols have some sort of multiplanar reconstruction built-in." He says that typically they review thicker slice axial and multiplanar reconstructions even though they acquire their axial data set at 0.5 mm to 1 mm collimation.

Robert Herfkens, MD, professor of radiology at Stanford University, explains in using their GE Healthcare LightSpeed 16 slice scanner, that although the majority of the studies produce 700 to 800 images, it is not unusual for their studies to produce between 2,000 and 3,000 images, especially for cardiac-gated studies or some vascular exams. The Centricity PACS allows him to "cine-scroll" through these massive image data files to the point of interest he seeks.

The Centricity PACS used with a multislice scanner requires a dedicated standard 100-megabit network. The high-end algorithms pull the data at the precise time the user needs to see the data. Rather than pulling 1,000 slices to a PC and waiting for them to transfer, Centricity pulls just