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."
Each cable carries electrical signals from the scanner to the sensors at the tip of the tube, which in turn send pulses of acoustic waves into the surrounding tissue, Smith explained. The sensors then pick up the returning echoes and relay them back to the scanner where they produce an image of the moving tissue or organ. The scanner uses parallel processing to listen to echoes of each pulse in 16 directions at once.
The laparoscopic ultrasound probes have so far been applied only to heart imaging, in which they may be particularly useful for monitoring heart function during minimally invasive cardiac surgery, Smith said. Current methods often monitor the heart with a 2D ultrasound endoscope probe down the throat, a method that requires general anesthesia.