64-slice CT transforms emergency radiology


Busy users share triumphs and tribulations with state-of-the-art scanners in trauma cases

After plunging into the brave new world of 64-slice CT, radiologists are singing the praises of advanced scanners for managing trauma patients, based on initial experience in the emergency room. The Stanford Multidetector-Row CT symposium in June featured a number of lectures highlighting both the benefits and the challenges of state-of-the-art systems in various ER scenarios.

With one year of 64-slice CT experience to draw upon, radiologists at Boston University Medical Center say their scanner's high resolution and isotropic nature both contribute to highly valuable reconstructions, according to Dr. Alexander Norbash, radiology chair.

The facility leapt directly from one four-slice and two single-slice scanners to three 64-slice CT devices in April 2005. BUMC scanned its 1000th patient with 64-slice CT this past May. Whereas CT was once deemed a great convenience, it is now considered essential for working up trauma patients, Norbash said. Installation of the new scanners has sparked an 18% increase in CT utilization at the center. If the 64-slice scanners go offline for some reason, the result is paralysis.

The technology has revolutionized head and neck imaging, particularly in trauma cases.

"The transition has been dramatic," Norbash said. "MRI has always been advantageous in the neck because of its polyplanar capability. Now, we have 64-detector scanners and the ability to perform rapid reconstructions, and it has made a tremendous difference."

The medical center admits about 1600 trauma patients annually. Vessels, airways, and bony compartments involved in head and neck trauma are easier to evaluate with 64-slice CT. Rapid rendering and various volume and surface-shaded imaging sets permit greater confidence and triage accuracy. Not only can regions be assessed tissue layer by tissue layer, but 64-slice CT also allows better understanding of differential considerations.

The speed and efficiency of image reconstructions have spurred an increase in the number of sinus CTs performed, while the volume of sinus x-rays has become nearly negligible. Sinus studies consist of axially obtained and coronally reformatted image sets. The preoperative value is perceived as much greater than that of the prior axial scan sets, Norbash said.

Management of trauma patients at nearby Massachusetts General Hospital has similarly been revolutionized by the recent installation of a 64-slice CT scanner in the facility's dedicated emergency radiology department. Dr. Robert Novelline, director of emergency room radiology, discussed the benefits of whole-body scanning of polytrauma patients with the latest CT technology at the Stanford symposium.

The technology provides greater anatomic coverage, faster speed to decrease motion artifact, and rapid whole-body single-acquisition trauma scans. Less intravenous contrast is needed, and it's possible to cardiac gate patients with pulsatile motion, Novelline said. With 64-slice CT, it's possible to do a single-acquisition body CT angiography study from vertex to pelvis, evaluate for most potentially fatal injuries in under two minutes, then continue with the runoff arteriogram.

At MGH, routine emergency cases such as suspected appendicitis are done on 16-slice CT. But 64-slice CT has become the study of choice for trauma cases, whole-body scans, and vascular imaging.

Following scanning, radiologists create multiplanar reformations immediately for the patient. At the push of a button, it's possible to perform volume rendering of bony structures and vascular structures. Three-D rendering has become essential to utilization of 64-slice CT, and these images are used as much as possible for making diagnoses.

For aortic injury, the scanners produce extraordinary images of vascular structures, Novelline said.

"Referring physicians have had their socks blown off by the quality of the images," he said.

Referring doctors can become "clinical champions" for 64-slice technology and possibly help make the case for greater resources to support the new scanners, Norbash said. He noted the dramatic effect of higher utilization on staffing models.

"It's not just about putting in a new scanner. It's about figuring out whether you have enough scanning slots, transporters, people to start IVs, residents to read the images. You have to jump through multiple hoops to get the hospital to understand why you need twice as many techs, and that is not easy to do in an emergency department," he said.

As utilization increases, so do concerns about excessive radiation dose exposure. At Boston University, radiologists have started to use noisier images in cases where the diagnostic value will not be compromised. Overuse is also a concern.

"If you have an 18% annual growth rate, a lot is probably unnecessary. The challenge for us as radiologists is where do we sit? How do we make sure the technology is not abused? It's not a popular topic with radiologists, but it is central to our responsibilities," Norbash said.

Protocols for which patients should actually get CTAs for suspected head injuries are evolving.

"We are on a continuous learning curve," Norbash said.

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