Compact Forward-Viewing Endoscopic Optical Coherence Tomography
Lead Research Organisation:
University of Kent
Department Name: Sch of Physical Sciences
Abstract
Optical coherence tomography (OCT) is a 3D high-resolution optical imaging technology. It is widely used for imaging internal structures of the eye and is also finding a range of other medical applications such as in dermatology and cardiology. It differs from conventional microscopy in that interferometry, together with a broadband or tunable optical source, is used to achieve optical sectioning. Through optical sectioning, and the intrinsic rejection of multiply-scattered light, OCT imaging is able to penetrate 1 to 2 mm inside scattering tissue, allowing 3D volumetric imaging. Using Fourier domain OCT techniques entire volumes can be collected, reconstructed and displayed in seconds.
Endoscopic OCT brings the high-resolution volumetric imaging capabilities of OCT to the interior of the body, opening up new possibilities for minimally-invasive diagnosis and interventional monitoring. Most endoscopic OCT systems work in a side-viewing configuration, where images are acquired radially outwards from the OCT probe, similar in appearance to endoscopic ultrasound. This works well for imaging narrow, tube-like structures (such blood vessels and parts of the gastrointestinal tract), but it is not ideal for areas such as the ear, nose and throat (ENT), for the upper airways, or for general surgical guidance. These applications would benefit from a probe that is forward looking; effectively an endoscope which produces high resolution en-face images or volumes from beneath the tissue surface.
However, forward-viewing OCT endoscopes are challenging to build with current technology as they require a two-dimensional fibre scanning mechanism to be built into the probe head; this scanning is typically either bulky, slow, or limited in scanning range, and leads to complex devices. This project, for the first time, proposes and evaluates solutions which add depth-resolving capabilities to en-face viewing endoscopes without a miniaturised scanner.
The research will explore a new approach for distal control of scattering and interference which is amenable to miniaturisation in the form of an adapter which could be fitted to a fibre imaging bundle or a miniature camera. The investigators have recently patented an approach for such a miniature adapter that makes use of a technique called full-field swept source OCT, where multiple images are captured, each at a different illumination wavelength, and processed to recover the OCT volume. To date there has been no report of good quality depth resolved imaging via a fibre bundle, and so if successful this project will represent a significant advance in the field of fibre bundle imaging.
The aims of the project are to demonstrate that the approach is a feasible and practical route to developing compact forward-viewing OCT probes with clinical utility. The earlier stages of the project involve developing a full understanding of the new technology. In parallel, a design will be developed for miniaturisation in collaboration with clinical partners advising on the design requirements. Packaged prototypes will then be developed, characterised and validated using a range of phantoms and tissue samples. In parallel with validation studies on the core probe design, additional scientific avenues will be pursued, including to combine the probe with other imaging modalities such as fluorescence.
The project will build on 25 years of experience of building OCT instrumentation in the Applied Optics Group at the University of Kent, as well as achievements in developing endoscopic microscopes and OCT probes and performing coherent imaging though fibre bundles. Industrial partners will provide expertise in miniaturised fibre optic components, compact probe packaging, and miniature cameras, while clinical partners from major hospitals will provide advice and support in developing the probe towards practical clinical applications in ear, nose and throat and the upper airways of the lungs.
Endoscopic OCT brings the high-resolution volumetric imaging capabilities of OCT to the interior of the body, opening up new possibilities for minimally-invasive diagnosis and interventional monitoring. Most endoscopic OCT systems work in a side-viewing configuration, where images are acquired radially outwards from the OCT probe, similar in appearance to endoscopic ultrasound. This works well for imaging narrow, tube-like structures (such blood vessels and parts of the gastrointestinal tract), but it is not ideal for areas such as the ear, nose and throat (ENT), for the upper airways, or for general surgical guidance. These applications would benefit from a probe that is forward looking; effectively an endoscope which produces high resolution en-face images or volumes from beneath the tissue surface.
However, forward-viewing OCT endoscopes are challenging to build with current technology as they require a two-dimensional fibre scanning mechanism to be built into the probe head; this scanning is typically either bulky, slow, or limited in scanning range, and leads to complex devices. This project, for the first time, proposes and evaluates solutions which add depth-resolving capabilities to en-face viewing endoscopes without a miniaturised scanner.
The research will explore a new approach for distal control of scattering and interference which is amenable to miniaturisation in the form of an adapter which could be fitted to a fibre imaging bundle or a miniature camera. The investigators have recently patented an approach for such a miniature adapter that makes use of a technique called full-field swept source OCT, where multiple images are captured, each at a different illumination wavelength, and processed to recover the OCT volume. To date there has been no report of good quality depth resolved imaging via a fibre bundle, and so if successful this project will represent a significant advance in the field of fibre bundle imaging.
The aims of the project are to demonstrate that the approach is a feasible and practical route to developing compact forward-viewing OCT probes with clinical utility. The earlier stages of the project involve developing a full understanding of the new technology. In parallel, a design will be developed for miniaturisation in collaboration with clinical partners advising on the design requirements. Packaged prototypes will then be developed, characterised and validated using a range of phantoms and tissue samples. In parallel with validation studies on the core probe design, additional scientific avenues will be pursued, including to combine the probe with other imaging modalities such as fluorescence.
The project will build on 25 years of experience of building OCT instrumentation in the Applied Optics Group at the University of Kent, as well as achievements in developing endoscopic microscopes and OCT probes and performing coherent imaging though fibre bundles. Industrial partners will provide expertise in miniaturised fibre optic components, compact probe packaging, and miniature cameras, while clinical partners from major hospitals will provide advice and support in developing the probe towards practical clinical applications in ear, nose and throat and the upper airways of the lungs.
