Optical coherence tomography: Technology and applications

Summary form only given. In the last two decades optical coherence tomography (OCT) has established itself as a unique non-invasive, optical medical diagnostic imaging modality, enabling unprecedented in vivo cross-sectional tomographic visualization of internal microstructure in a variety of biological systems. Ophthalmology has been the most successful and commercially most active medical field for OCT so far, but several other OCT applications, e.g. in cardiology, dentistry, gastroenterology or dermatology, are on the verge of expanding their market comparable to or larger than that of ophthalmology.Especially in the last decade ultrabroad bandwidth light sources as well as spectral/frequency domain OCT detection technology enabled three-dimensional ultrahigh resolution OCT with unprecedented axial resolution, approaching resolution levels of conventional histopathology, enabling optical biopsy of biological tissue. Furthermore emerging swept source laser technologies and parallel or full-field OCT techniques enabled multiple millions of A-scan rates per second, allowing large area OCT scans with high definition sampling, investigation of dynamic processes or four-dimensional (3D over time) imaging. In addition, extensions of OCT are under development that should provide enhanced contrast or non-invasive depth resolved functional imaging of the investigated tissue, including extraction of birefringent, spectroscopic, blood flow or physiologic tissue information. These extensions of OCT should not only improve image contrast, but should also enable the differentiation and early detection of pathologies via localized functional state. Recently OCT has also been combined with different complementary imaging technologies (photoacoustics, CARS, multi-photon microscopy, fluorescent imaging, ultrasound, adaptive optics) to hybrid/multi-modal approaches to compensate fundamental limits of OCT in order to significantly enhance its performance towards molecular imaging.