Optical Coherence Tomography (OCT) is a promising new class of diagnostic medical imaging technology that utilizes advanced photonics and fiber optics to obtain images and tissue characterization on a scale never before possible within the human body. When fully exploited, the technology has the potential to dramatically change the way physicians, researchers and scientists see and understand the human body in order to better diagnose and treat disease.
Simply put, OCT combines the principles of ultrasound with the imaging performance of a microscope and a form factor that is familiar to clinicians. Whereas ultrasound produces images from backscattered sound “echoes,” OCT uses infrared light waves that reflect off the internal microstructure within the biological tissues. The frequencies and bandwidths of infrared light are orders of magnitude higher than medical ultrasound signals — resulting in greatly increased image resolution – 8-25 times greater than any existing modality.
Infrared light is delivered to the imaging site through a single optical fiber only .006″ diameter (about the size of the period in this sentence). The imaging guidewire contains a complete lens assembly to perform a variety of imaging functions. The guidewire can be deployed independently or integrated into existing therapeutic or imaging catheters.
OCT imaging can be performed over approximately the same distance of a biopsy at high resolution and in real time making the most attractive applications for OCT those where conventional biopsies cannot be performed or are ineffective. (Huang, Science 254:1178, 1991)
While standard electronic techniques are adequate for processing ultrasonic echoes that travel at the speed of sound, interferometric techniques are required to extract the reflected optical signals from the infrared light used in OCT. The output, measured by an interferometer, is computer processed to produce high-resolution, real time, cross sectional or 3-dimensional images of the tissue. This powerful technology provides in situ images of tissues at near histological resolution without the need for excision or processing of the specimen.
In addition to providing high-level resolutions for the evaluation of microanatomic structures OCT is inherently able to provide information regarding tissue composition. Using spectroscopy, users can evaluate the spectral absorption characteristics of tissue while simultaneously determining the orderliness of the tissue through the use of polarization imaging.