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Optical coherence tomography (OCT) is a non-invasive imaging technique that uses light waves to capture micrometer-resolution, two-dimensional cross-sectional and three-dimensional images from within optical scattering media, such as biological tissue. OCT enables visualization of tissue microstructures with resolutions of a few micrometers by employing coherence gating of back-reflected or back-scattered light. Some of the major clinical applications of OCT include ophthalmology, cardiology, dermatology, gastroenterology and ENT. In recent years, there have been rapid advancements in OCT technology which have enabled new applications and improved imaging capabilities. This article discusses the technological advancements in Optical Coherence Tomography Devices and their clinical applications.
Advancements in OCT technology
Ever since its inception in the early 1990s, OCT technology has seen tremendous advancements that have greatly improved imaging resolution, speed and functionality. Some of the key advancements include:
– Swept-source OCT (SS-OCT): Swept laser sources significantly improved imaging speed and allowed real-time in vivo 3D volumetric acquisitions at much higher resolutions compared to previous time-domain OCT systems. SS-OCT is now the standard for many clinical ophthalmic and coronary imaging applications.
– Ultrahigh resolution OCT: Next generation OCT devices achieve resolutions as high as 1-2 microns by employing broad bandwidth light sources, advanced optics and signal processing techniques. This has enabled clear visualization of microscopic tissue structures.
– Doppler OCT: Enhancements such as Doppler OCT enable functional imaging by detecting blood flow and microvasculature deep within tissues. This has applications in diagnosis and management of diseases affecting microvasculature such as age-related macular degeneration.
– Optical frequency domain imaging (OFDI): OFDI variant of OCT combines benefits of Fourier domain detection and swept-source scanning. It provides improvements in sensitivity, imaging speed and resolution for clinical applications such as intravascular coronary artery imaging.
– Full-field OCT: Alternative to conventional OCT, full-field OCT enables wide field-of-view 3D volumetric imaging without any mechanical scanning. It provides several advantages for applications such as dermatology and whole slide pathology imaging.
Advances in OCT systems have translated to improved clinical applications and introduction of new functionalities. The sections below discuss some prominent applications of modern high speed, high resolution OCT devices.
Applications in ophthalmology
Ophthalmic OCT imaging is considered the reference standard for evaluating many posterior segment eye diseases. Modern OCT devices provide detailed depth-resolved imaging of the retina and optic nerve at very high resolutions. Some key applications include:
– Glaucoma diagnosis and monitoring: Retinal nerve fiber layer and ganglion cell layer thickness maps from OCT help diagnose and track glaucoma progression. OCT is now the primary diagnostic tool for glaucoma.
– Macular diseases: Pathologies affecting the macula such as age-related macular degeneration, cystoid macular edema, diabetic macular edema etc. are accurately diagnosed, staged and monitored with OCT.
– Retinal diseases: Diseases of the outer retina such as drusen deposits, vitreomacular traction, epiretinal membranes etc. causing visual impairment are clearly visualized on OCT scans.
– Cataract surgery: Anterior segment OCT provides high resolution pre-operative evaluation of cataracts, measurements for lens implants and post-op assessment.
The non-invasive, quick acquisition and precise quantitative measurements enabled by ophthalmic OCT devices have made it an indispensable tool for retina specialists.
Applications in cardiology
Intravascular OCT (IVOCT) provides intraluminal, cross-sectional visualization of coronary arteries with resolutions better than 10 microns. Some key cardiovascular applications include:
– Detection of atherosclerotic plaques: IVOCT precisely detects characteristics of plaques like size, composition and thin-cap fibroatheromas indicating vulnerability to rupture.
– Guidance for interventions: Real-time IVOCT imaging guides interventional cardiologists for accurate stenting, avoiding plaque disruption during procedures.
– Assessment of stent apposition: Post stenting, OCT checks for proper apposition and expansion of stents, detecting malapposition or incomplete coverage.
– Vascular graft monitoring: OCT enables long term monitoring of bypass and other grafts for neointimal hyperplasia, detecting graft failures early.
Uniquely providing depth-resolved views of vessel wall structure, IVOCT has become an important tool for diagnosing vulnerable plaques, optimizing interventional strategies and monitoring vascular devices.
Other clinical applications
Besides the above major specialties, modern high resolution OCT systems also find use in:
– Gastroenterology: Endoscopic OCT imaging aids detecting superficial mucosal lesions, differentiated layers of the gastrointestinal wall.
– Dermatology: Handheld OCT devices enable rapid diagnosis of skin cancers, infections, inflammatory conditions non-invasively.
– Dentistry: OCT imaging helps examining caries, cracks below fillings, soft tissue and bone pathologies in oral cavity.
– ENT: Middle ear imaging allows assessing functions of eardrum, ossicles and auditory nerves in normal and diseased conditions.
Conclusion
Constant refinements in OCT technology have resulted in systems with higher resolutions, faster acquisition speeds and new functionalities. These advances have greatly expanded clinical applications of OCT across specialties such as ophthalmology, cardiology, dermatology and ENT. OCT provides high value guidance for diagnosis and management decisions by offering non-invasive cross-sectional or volumetric visualization of tissue microstructure. With further development, Optical Coherence Tomography Devices will likely become more compact, affordable and versatile diagnostic tools.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
