Q+A CENTER

Laparoscopic ultrasound probes, so far, have been used only for cardiac applications where they are particularly effective for monitoring the heart during minimally invasive surgery. Current methods observe the heart with a 2D ultrasound endoscopic probe, inserted down the throat. By contrast, the laparoscopic ultrasonographic imager could function for hours through a tiny incision and possibly obviate the need for general anesthesia. Similar 3D ultrasound devices also hold promise for minimally invasive abdominal and brain surgery.

Spectrally-Encoded Endoscopy

Relying on external sensors to produce high-quality, two-dimensional images, regulation endoscopes can be a centimeter or more in diameter. For accessing harder-to-reach internal structures, standard miniature endoscopes contain smaller fiber bundles and may be more flexible, but often compromise image quality.

A miniature instrument, developed at Massachusetts General Hospital's Wellman Center for Photomedicine (Boston), is expanding the fields of minimally invasive diagnosis and therapy. Unlike conventional endoscopes which use bundles of optical fibers to supply light to and transmit images from areas of interest, the invention employs spectrally-encoded endoscopy (SEE) and is only about the width of a human hair.

With SEE, multicolored light from a single optical fiber is broken into its component wavelengths and projected onto the target. Light reflected back into the instrument is recorded and each color's intensity is decoded by a spectrometer. An interferometer calculates structural information-from the interaction between light waves-and creates three-dimensional depth information.

"This new technology will offer physicians and surgeons the capability to bring many more procedures into outpatient settings, reduce anesthesia requirements and minimize tissue damage," said Guillermo Tearney, associate professor of pathology at Harvard Medical School (Cambridge, Mass.). "The device's size and flexibility should allow safer navigation through such delicate structures as the salivary ducts, the fallopian tubes and the pancreatic duct. Fetal and pediatric procedures may also benefit from this tool. Eventually, SEE could give rise to new procedures that permit diagnosis and microsurgery in previously inaccessible areas of the body."