Scientists at the Massachusetts Institute of Technology (MIT) have developed a new high-speed, three-dimensional endoscopic imaging system. They described the technology called optical coherence tomography (OCT) this week in the Optical Society’s open access journal Biomedical Optics Express. This method makes it possible to see microscopic pre-cancerous changes in the esophagus and colon.
OCT itself is not a new technology, it has become commonplace in ophthalmology, where it is being used to generate images of the retina and to help diagnose and monitor diseases like glaucoma. Now OCT pioneer James G. Fujimoto of MIT and his colleagues made this technique also available for endoscopic imaging.
The method is almost analogous to medical ultrasound imaging except that it uses light instead of sound waves to visualize structures in the body in real time, and with higher resolution. Microscopic structural and pathological features are examined by directing a beam of light on a tissue and measuring the magnitude and echo time-delay of backscattered light. The technique can generally only be used to visualize microscopic sub-surface features to a depth of 1 to 2 millimeters.
Fujimoto is cited in the press release from the Optical Society (OSA):
“This device development is one of the major technical challenges in endoscopic OCT because probes must be small enough so that they can be introduced into the body, but still be able to scan an optical beam at high speeds. Increasing imaging speeds has also been an important research objective because high-resolution volumetric imaging requires very large amounts of data in order to cover appreciable regions of tissue, so rapid image acquisition rates are a powerful advantage.”
The optical catheter uses a piezoelectric transducer, a miniature device that bends in response to electrical current, allowing a laser-light emitting optical fiber to be rapidly scanned over the area to be imaged. But before this can be deployed with standard endoscopes now used it has to be further reduced in size. Up till now is has only been used in animal models and human colons that had been removed during surgical procedures. Further development and testing is needed before it can be used in human patients.
Abstract in Biomedical Optics Express: Piezoelectric-transducer-based miniature catheter for ultrahigh-speed endoscopic optical coherence tomography