Compact and multimodal OCT demonstrate technique's growth potential

27 Oct 2021

Survey finds that three decades after its invention OCT is set to support a $1.5 billion market.

OCT was first demonstrated in 1991 by James Fujimoto at MIT, and the thirty years since have indicated the value of the technique for medical imaging.

Although OCT was readily adopted by ophthalmology clinics thanks to its easy alignment with their workflows and requirements, the core technology has benefited from continuing strides in optical sources and photonics components, and OCT is now positioned as a potentially major technique in optical biopsies.

A review authored by the Medical University of Vienna and published in Journal of Biomedical Optics predicts that the global market for OCT in 2023 will be $1.5 billion, and noted that this would include hand-held OCT units in addition to established integrated systems.

"With its exquisite non-invasive, micrometer-resolution depth sectioning capability, OCT has especially revolutionized ophthalmic diagnosis and hence is the fastest adopted imaging technology in the history of ophthalmology," noted the report. "Nonetheless, OCT has not been completely exploited and has substantial growth potential."

Detailing the advances now being made by modern OCT platforms, the report noted that cost-effective swept source laser technology and efficient scanning schemes will enable OCT A-scan rates beyond 1 megahertz to become a standard OCT specification in the very near future.

This in turn will assist the development of smaller, hand-held OCT instruments, in which high scan rates are needed in order to reduce motion artifacts during use. Newly emerging OCT-on-a-chip, home-OCT, and self-OCT systems based on micro-optic assemblies or photonic integrated circuits will also be key aspects of miniaturized platform architectures.

Such compact systems are likely to assist OCT's entry into markets outside its established ophthalmology base, with several developers looking to take advantage. In 2015 Compact Imaging developed a miniaturized platform christened multiple reference OCT (MR-OCT) for potential uses in smartphones, tablets and wearables. Compact Imaging is now targeting MR-OCT at home-use ophthalmology uses.

"The technology of miniaturized OCT is still young and foreshadows an exciting future of more widespread, mainstream, automated, intelligent, and smart point-of-care devices for early detection of pathological changes," commented the JBO report's co-author Wolfgang Drexler. "It is expected that the handheld OCT devices segment can make significant progress in the years ahead, entering new larger unexploited markets for OCT."

OCT take-off is imminent

Multimodal platforms incorporating OCT alongside complementary optical imaging methods are also identified by the report as a major growth area, allowing the relative deficiencies of OCT in terms of penetration depth and limited contrast to be balanced by the capabilities of other modalities in the same system.

This principle has a long pedigree, with researchers unveiling the first system to combine OCT and Raman spectroscopy back in 2008. As reported by Optics.org at the time, the goal was to assist in the optical detection and diagnosis of epithelial cancers, such as skin cancer.

This path continues to yield results, with the recent Horizon 2020 PROSCOPE consortium aiming to combine OCT and Raman with multi-photon microscopy in an endoscopy-based multimodal platform for the detection of early-stage bowel cancer.

"Multimodal imaging applications combining techniques complementary to OCT will more and more be transferred from microscopy setups - acting as fast quasi-histological optical biopsies next to the operating room - to the miniaturized endoscopic level," commented Drexler. "OCT will act like a GPS by prescreening the tissue at a wider field of view with microscopic resolution."

Despite these breakthroughs, the JBO report also noted that widespread adoption of OCT outside of ophthalmology had been somewhat inhibited by the presence of established less expensive and more widely recognized imaging modalities.

This will change as cost-effective OCT "is enabled by technological advancements like photonic integration and the availability of cheaper swept-source laser technology," said Drexler and the report's co-authors. "Take-off is imminent."