Optical coherence tomography

Optical coherence tomography (OCT) is a high-resolution imaging technique with most of its applications in medicine and biology. OCT uses coherent near-infrared light to obtain micrometer-level depth resolved images of biological tissue or other <a href="/facts/Scattering/nMou7lEH">scattering</a> media. It uses <a href="/facts/Interferometry/X3E1SsQT">interferometry</a> techniques to detect the amplitude and time-of-flight of reflected light.
OCT uses transverse sample scanning of the light beam to obtain two- and three-dimensional images. Short-coherence-length light can be obtained using a <a href="/facts/Superluminescent_diode/M8Ivbuak">superluminescent diode</a> (SLD) with a broad <a href="/facts/Spectral_bandwidth/7eMDzfJI">spectral bandwidth</a> or a broadly tunable laser with narrow <a href="/facts/Linewidth/HuI4Bj5f">linewidth</a>. The first demonstration of OCT imaging (in vitro) was published by a team from MIT and Harvard Medical School in a 1991 article in the journal <a href="/facts/Science_(journal)/uTyzjkwD">Science</a>. The article introduced the term "OCT" to credit its derivation from optical coherence-domain <a href="/facts/Reflectometry/8u9v4PAL">reflectometry</a>, in which the axial resolution is based on <a href="/facts/Temporal_coherence/NF1Rgdoa">temporal coherence</a>. The first demonstrations of in vivo OCT imaging quickly followed.
The first US patents on OCT by the MIT/Harvard group described a <a href="/facts/Time-domain/1w6mP2MU">time-domain</a> OCT (TD-OCT) system. These patents were licensed by Zeiss and formed the basis of the first generations of OCT products until 2006.
In the decade preceding the invention of OCT, interferometry with short-coherence-length light had been investigated for a variety of applications.[excessive citations] The potential to use interferometry for imaging was proposed, and measurement of <a href="/facts/Retina/v0ISNX2S">retinal</a> elevation profile and thickness had been demonstrated.
The initial commercial clinical OCT systems were based on point-scanning TD-OCT technology, which primarily produced <a href="/facts/Cross_section_(geometry)/g5R1c6v2">cross-sectional</a> images due to the speed limitation (tens to thousands of axial scans per second). Fourier-domain OCT became available clinically 2006, enabling much greater image acquisition rate (tens of thousands to hundreds of thousands axial scans per second) without sacrificing signal strength. The higher speed allowed for three-dimensional imaging, which can be visualized in both en face and cross-sectional views. Novel contrasts such as <a href="/facts/Angiography/4onftT3X">angiography</a>, <a href="/facts/Elastography/0nFnL0z1">elastography</a>, and optoretinography also became possible by detecting signal change over time. Over the past three decades, the speed of commercial clinical OCT systems has increased more than 1000-fold, doubling every three years and rivaling <a href="/facts/Moore%27s_law/90CSekhl">Moore's law</a> of computer chip performance. Development of parallel image acquisition approaches such as line-field and full-field technology may allow the performance improvement trend to continue.
OCT is most widely used in <a href="/facts/Ophthalmology/024hdTWF">ophthalmology</a>, in which it has transformed the diagnosis and monitoring of retinal diseases, <a href="/facts/Optic_nerve/3AJDdVN5">optic nerve</a> diseases, and <a href="/facts/Cornea/oKA6clQT">corneal</a> diseases. It has greatly improved the management of the top three causes of blindness – <a href="/facts/Macular_degeneration/9pFARaka">macular degeneration</a>, <a href="/facts/Diabetic_retinopathy/qjtejArl">diabetic retinopathy</a>, and <a href="/facts/Glaucoma/MWqWVNz3">glaucoma</a> – thereby preventing vision loss in many patients. By 2016 OCT was estimated to be used in more than 30 million imaging procedures per year worldwide.
Intravascular OCT imaging is used in the intravascular evaluation of <a href="/facts/Coronary_arteries/Xsx1dekd">coronary artery</a> plaques and to guide <a href="/facts/Stent/h8Ss3zlE">stent</a> placement. Beyond ophthalmology and cardiology, applications are also developing in other medical specialties such as <a href="/facts/Dermatology/YfvJ8uXn">dermatology</a>, <a href="/facts/Gastroenterology/89aMlDF0">gastroenterology</a>, <a href="/facts/Neurology/TXYEMSYI">neurology</a> and neurovascular imaging, <a href="/facts/Oncology/t2CUAEJQ">oncology</a>, and <a href="/facts/Dentistry/p8b1zmts">dentistry</a>.

Optical coherence tomography open-in-new

Optical coherence tomography