Optical Coherence Technology (OCT), a favored tool of eye specialists for nearly two decades, may soon be coming to an esophagus or colon near you.
Researchers from the Massachusetts Institute of Technology have developed an experimental imaging system that enables high-speed, three-dimensional imaging of subsurface microscopic precancerous changes in the esophagus or colon, they reported in The Optical Society’s open access journal Biomedical Optics Express.
OCT uses light near the visible spectrum to create 3D images below the surface of tissues with accuracies of a few microns. The study describes a piezoelectric-transducer-based miniature catheter with an outer diameter of 3.5 mm capable of 11 micron axial resolution in air and 8 micron resolution in tissue at a rate of 960 frames per second — 10 times faster than previous versions. They worked with rabbit esophagus and colon in vivo and human colon specimens ex vivo.
The piezoelectric transducer, a miniature device that bends in response to electrical current, allows a laser-light emitting optical fiber to be rapidly scanned over the area to be imaged. While OCT technology tends to peter out at depths beyond a millimeter or two, that’s comparable to pinch biopsies, and with OCT scanning, the data’s available real-time, said lead author James G. Fujimoto, PhD, of MIT.
Fujimoto and colleagues say the system promises to enable 3D microscopic imaging of precancerous changes in the esophagus or colon and the guidance of endoscopic therapies. Esophageal and colon cancer are diagnosed in more than 1.5 million people worldwide each year, according to the American Cancer Society.
“This new system represents a significant advance in real-time, 3D endoscopic OCT imaging in that it offers the highest volumetric imaging speed in an endoscopic setting, while maintaining a small probe size and a low, safe drive voltage,” said Xingde Li, associate professor at the Whitaker Biomedical Engineering Institute and Department of Biomedical Engineering at Johns Hopkins University, who is not affiliated with the research team.
In collaboration with clinicians at the VA Boston Healthcare System and Harvard Medical School, the team is investigating endoscopic OCT as a method for guiding excisional biopsy — the removal of tissue for histological examination — to reduce false negative rates and improve diagnostic sensitivity.
Fujimoto says the device must be further reduced in size before it can be deployed with the standard endoscopes, and FDA testing lies ahead. The MIT team is one of a number of research groups — including at Johns Hopkins University; the University of California, Irvine; Case Western University; and Massachusetts General Hospital — working on smaller, faster endoscopic OCT systems.