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 - Northwestern Memorial Hospital - Chicago

Cardiac and Other Patient Groups Garner Substantial Benefit from Northwestern Memorial's Dual Source, Dual-Energy CT Scanner

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June 7, 2007

Chicago -

This high-powered x-ray device removes the need for beta-blockers—a heart-rate slowing medication that is off limits to an expansive group of cardiac patients who cannot take the drug.

Northwestern Memorial Hospital is Chicago’s first academic medical center to install a dual source, dual energy computed tomography (CT) scanner — a large-scale diagnostic X-ray instrument that captures high-quality images of human tissue, even amidst certain rapid motion like that of a fast beating heart. Known as a CT scanner, until now the single source, single energy, 64-slice CT scanner was the fastest imaging hardware available. With double the speed and power, images obtained by this new scanner are even more telling. This is a tremendous breakthrough for many heart disease patients where diagnostic imaging required oral or intravenous administration of beta-blockers to slow the heart rate in order to improve the quality of the scan. The new dual source scanner eliminates the need for beta-blockers in most patients.

“This is of enormous benefit to cardiac patients because many of them have contraindications to beta-blockers to start with, meaning they either cannot take the drug or will not experience sufficiently reduced heart rates by taking the drug,” said James Carr, MD, Director of Cardiovascular Imaging at Northwestern Memorial Hospital department of Radiology. “Although the 64-slice CT scanner is still ideal for many applications, the fact that we can now visualize the coronary arteries in even greater detail, without having to administer drugs, is very good news for heart patients. There is just so much more that we are able to see and detect because the resolution of the images is substantively enhanced.”

Since this new scanner effectively operates at twice the speed of other CT scanners, it produces more detailed images of coronary stents, which up until now were difficult to assess with conventional CT.

To produce a CT image, computer-driven machinery passes X-rays through the body, producing digitized signals that are detected and reconstructed. Each X-ray measurement lasts just a fraction of a second and represents a "slice" of an organ or tissue. The greater the number of detectors, the better the speed and resolution of the picture. A computer then uses these slices to reconstruct highly detailed, 3-D images of the heart, other organs, and blood vessels throughout the body.  In most cases, a patient is injected with a contrast solution to increase the visual detail.

The scanner will also be used for other important applications, such as identifying narrowed brain arteries that put patients at risk of having a stroke, and for evaluating blood flow in other organs such as the liver and kidneys. Developing specific clinical protocols for scanning patients with certain kinds of symptoms will be a continuing process, and extending the use of cardiac CT is a collaborative effort between the Section of Cardiovascular Radiology led by James Carr, MD, and Northwestern Memorial’s Bluhm Cardiovascular Institute.

The scanner is formally known as the Siemens® Definition CT and it is manufactured by Siemens Medical Solutions.  Its features include production of images much faster than what is possible with current 4-slice, 16-slice and 64-slice scanners and it generates 3-dimensional images for diagnostic treatment planning.


Last UpdateAugust 8, 2011