Washington: An ultrasound probe small enough to sit on a catheter tip can provide physicians with clearer images of soft tissue, minus risks associated with x-ray catheter guidance.

Duke University biomedical engineers designed and fabricated the ultrasound probe which is powerful enough to provide detailed, 3-D images. It works like an insect's compound eye, blending images from 108 miniature transducers working together.

"There are no technological barriers left to be overcome," said Stephen W. Smith, director of the University's Ultrasound Transducer Group and co-author of the study.

"While we have shown that the new probe can work for two types of procedures, we believe that results will be more far-reaching," Smith said.

"There are many catheter-based interventional procedures where 3-D ultrasound guidance could be used, including heart valve replacements and placement of coils in the brain to prevent stroke. Wherever a catheter can go, the probe can go."

Catheter-based procedures involve snaking instruments through blood vessels to perform various tasks, such as clearing arteries or placing stents, usually with the guidance of x-ray images.

In a series of proof-of-principle experiments in a water tank using simulated vessels, the engineers used the new ultrasound probe to guide two specific procedures: the placement of a filter within a vessel and the placement of a synthetic "patch" for aortic aneurysms. The scientists plan to begin animals tests within the year.

Currently, when manoeuvering a catheter through a vessel, physicians rely on x-ray images taken from outside the body and displayed on a monitor to manipulate their instruments. Often, a contrast agent is injected into the bloodstream to highlight the vessel.

"While the images obtained this way are good, some patients experience adverse reactions," said research engineer Edward Light, co-author of the study and designer of the new probe.

"Also, the images gained this way are fleeting. The 3-D ultrasound guidance does not use x-ray radiation or contrast agents, and the images are real-time and continuous."

Another benefit is portability, which is an important issue for patients who are too sick to be transported, since x-rays need to be taken in specially equipped rooms, Light said. The 3-D ultrasound machine is on wheels and can be moved easily to a patient's room.

The results have been published online in IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control and will feature as the cover story in its September issue. IANS