Three-dimensional ultrasound probes built by researchers at Duke's Pratt School of Engineering have imaged the beating hearts of dogs. The engineers said their demonstration showed that the probes could give surgeons a better view during human endoscopic surgeries in which operations are performed through tiny "keyhole" incisions.
If the probes prove beneficial in human testing, the advance might lead to more precise and safer endoscopic surgeries, said the Duke engineers. The researchers reported their advance in the latest issue of the journal Ultrasonic Imaging, which was issued in late March 2006, but dated July 2005. The research was supported by the National Institutes of Health and the National Science Foundation.
"Surgeons now use optical endoscopes or two-dimensional ultrasound when conducting minimally invasive surgery," said lead engineer Stephen Smith, a professor of biomedical engineering at the Pratt School. Optical endoscopes are thin tubes with a tiny video camera that surgeons can insert directly into the abdomen or chest through small incisions.
"With our scanner, doctors could see the target lesion or a portion of an organ in a real-time three-dimensional scan," Smith said. "They would have the option of viewing the tissue in three perpendicular cross-sectional slices simultaneously or in the same way a camera would see it -- except that a camera can't see through blood and tissue."
The technology has yet to be tested in human patients, but its success in dogs makes it ready for clinical trials, according to the researchers.
Endoscopic surgical methods have the advantage of reduced postoperative pain and a faster recovery. However, the two-dimensional ultrasound imaging now available offers surgeons only a limited view, which can impede their depth perception and make such procedures difficult to master.
"Our ultrasound device could really advance the use of minimally invasive surgery," Smith said. "By allowing surgeons to essentially see through the body to the site of interest in three dimensions, the scanner could make such surgeries easier to perform and eventually more precise." Such surgeries also might be cheaper and less traumatic as they could be performed in less time and, in some cases, without the need of general anesthesia, he said.
Duke developed the first 3D ultrasound scanner in 1987 for imaging the heart from outside the body. As technology enabled ever smaller ultrasound arrays, the researchers engineered probes that could fit inside catheters threaded through blood vessels to image the vasculature and heart from the inside out.
The current advance relies on 500 tiny cables and sensors packed into a tube 12 millimeters in diameter -- the size required to fit into surgical instruments, called trocars, that surgeons use to allow easy exchange of laparoscopic tools. By comparison, most two-dimensional ultrasound probes use just 64 cables.
"It's a feat of technology and craftsmanship to build these devices," Smith said. "More cables translate into better image quality. The scanners achieve a 3D moving image instantaneously, with no reconstruction."