64-slice CT makes inroads in chest pain and trauma

Adoption of 64-slice scanners by trauma and emergency departments is on the rise, with facilities citing improved diagnosis and management of patients with severe injuries and chest or abdominal pain.

The use of 64-slice CT scanners in the ER allows more accurate and innovative diagnosis with new reconstruction capabilities, enabling ER physicians to perform several specialized imaging tests on the CT table almost simultaneously, said Dr. Michael Blaivas, an ER physician at the Medical College of Georgia.

"We will likely see more CT angiography, which gives us greater accuracy for vascular injuries, and less use of traditional angiography in trauma patients," he said.

Most 64-slice CT studies presented at the 2005 RSNA meeting focused on its value as a triage tool for ER patients with chest pain. As evidenced by the 2006 American Roentgen Ray Society meeting, researchers are now branching out, expanding applications and tweaking those already accepted.

Researchers at Emory University used 3D reconstructions of abdomen/pelvic exams in 50 ER patients undergoing 64-slice CT. They found the combined evaluation of transverse images and multiplanar coronal reformats added value to their GI tract evaluations.

At the University of Washington in Seattle, researchers led by Dr. Paul E. Kinahan developed a radiation dose reduction technique for use in patients undergoing the triple rule out: evaluation of coronary artery disease, thoracic aortic dissection, and pulmonary embolism. Using a 64-slice scanner, investigators found that the combination of an ECG-based mAs modulation method and a lowered heart rate significantly reduced radiation dose. The tube current swings up and down in sync with the cardiac cycle, with best dose reduction at heart rates ranging from 40 to 75 beats per minute.

Sixty-four slice CT provides greater anatomic coverage, speed, images of exquisitely high resolution, nearly instantaneous 3D reformations, and CT angiography, which helps pinpoint complex fractures and vascular injuries in trauma patients, said Dr. Robert A. Novelline, director of emergency radiology at Massachusetts General Hospital.

"If you are wondering where to place the 64-slice scanner, you want to put it very close to the emergency department," he said. "Not only for trauma, but also because that's where the acute chest pain will appear."

Not everybody agrees. Many trauma centers already include CTA in their diagnostic protocols for stable patients with multiple blunt cerebrovascular and thoraco-abdominal injuries. In these cases, as in coronary imaging, the procedure requires contrast injection and scanning delay, leading to increased radiation dose. The use of 64-slice CT in the ER requires more studies with careful assessment on risks, costs, and benefits for the individual patient, said Dr. Stephen R. Baker, editor-in-chief of Emergency Radiology.

"When we get ours, we are not going to put it in the trauma suite. We already have 16-slice scanners there, which we think are fine," he said.