"When we looked into it further, we found that these artifacts occurred in 5 to 10 percent of the scans," Judd explained. "After more research into the phenomenon, we decided to try to harness the effect rather than get rid of it."

As it turned out, the strange images appeared whenever a blood vessel ran perpendicular to the plane of the scan. So the researchers rotated the scanner, adjusted the radiofrequency of the scanner and developed a complex new way of capturing the images.

"As the blood cell flows through the plane, it is excited by the MRI," Judd explained. "While the next cell is also excited when it flows through, the first cell still gives off a radio-frequency signal that we can detect, on so on. We receive a continuous image of the blood flow."

The blood remains "excited" for about 13 centimeters from the point of excitation, Judd said.

For Judd, the new approach gives clear three-dimensional information on two important aspects of cardiovascular disease -- the actual anatomy of the vessel, as well as the speed and direction of blood flow.

"Information on flow is important because anatomy and function are not always related," he explained. "In one patient, a 70 percent blockage of an artery may hinder blood flow enough to cause cell death, while in the next patient, due to subtle differences in the three-dimensional shape and length of the blockage, there may not be the same problem."

The current studies were performed on the aortas of human volunteers. The aorta was chosen for the initial studies because it is one of the largest vessels in the body and it is easily accessible.

Judd sees one of the immediate uses of the new technique on the renal arteries. Constrictions in the renal arteries are common causes of hypertension, and since the new technique does not use contrast agents, patients should be able to better tolerate the procedure, J
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Contact: Richard Merritt
merri006@mc.duke.edu
919-684-4148
Duke University Medical Center
4-Apr-2004