Three-dimensional endomicroscopy using optical coherence tomography

Optical coherence tomography enables micrometre-scale, subsurface imaging of biological tissue by measuring the magnitude and echo time delay of backscattered light. Endoscopic optical coherence tomography imaging inside the body can be performed using fibre-optic probes. To perform three-dimensional optical coherence tomography endomicroscopy with ultrahigh volumetric resolution, however, requires extremely high imaging speeds. Here we report advances in optical coherence tomography technology using a Fourier-domain mode-locked frequency-swept laser as the light source. The laser, with a 160-nm tuning range at a wavelength of 1,315 nm, can produce images with axial resolutions of 5–7 µm. In vivo three-dimensional optical coherence tomography endomicroscopy is demonstrated at speeds of 100,000 axial lines per second and 50 frames per second. This enables virtual manipulation of tissue geometry, speckle reduction, synthesis of en face views similar to endoscopic images, generation of cross-sectional images with arbitrary orientation, and quantitative measurements of morphology. This technology can be scaled to even higher speeds and will open up three-dimensional optical-coherence-tomography endomicroscopy to a wide range of medical applications.