Funding available until: 10 February 2017
Functional optical coherence tomography (OCT) enables high quality, ultrafast, qualitative and quantitative characterisation of tissue structure and function in vivo. It can be used in basic biomedical research and clinical medicine as a rapid non-invasive method for tissue disease diagnosis, long-term tissue monitoring and optimisation of treatment. Animals can be studied longitudinally using this approach, greatly reducing the number of animals required for each study. The technology developers, from the University of Dundee, are seeking partners interested in applying the system to their research to assess the utility of the technology in a wide variety of applications.
Tissue assessment is important in a variety of different applications, including clinical diagnosis and treatment, pharmaceutical and chemical development, and tissue engineering. The most basic and important parameter assessed is tissue structural information which indicates change on a cellular level. However, structural information alone is not enough to fully understand the tissue physiology.
Functional imaging technologies for tissue characterisation are being increasingly used in a variety of applications, for example in disease/cancer diagnosis and for real time assessment in tissue engineering. Tissue characterisation includes measurement of microvascular distribution, blood velocity mapping, and tissue stiffness mapping. These act as indicators of functional changes and variations in the micro-structure that are useful for understanding tissue pathophysiology. The vasculature is a key player in promoting tissue survival as it carries the tissue's blood supply and is the site for the initiation of inflammatory events in the affected area, while the alteration of mechanical properties of biological tissues, especially the stiffness, directly correlates with the tissues’ pathological status.
Our newly developed system combines both structural imaging and characterisation of tissue, making it an important tool for monitoring tissue development and survival with several advantages over alternative systems:
- Measurement of tissue structure can attain axial and transverse resolution of up to ~6 µm and ~12 µm, with an image depth of up to 3 mm. Based on this, functional OCT has the potential to assess structural changes in living tissue at a microscopic level (7-9).
- Functional OCT is designed for visualising capillary networks and detecting flow direction/velocity changes as well as determining both the vascular and surrounding tissue remodelling and growth (10-14). Functional OCT blood vessel mapping is a label-free technique; it uses the intrinsic light scattering from flowing blood cells within patent vessels to produce the imaging contrast. Our recent development of the system has an ultra-high sensitivity to the blood flow down to 4 µm/s (10; 11).
- Functional OCT enables quantitative characterisations of mechanical properties, e.g. elastogram, with ultra-high sensitivity.
Histological analysis of biopsied tissue remains the gold standard for tissue assessment. It enables clear visualisation of cellular behaviour and structural architecture (1). However, this method has some limitations: 1) it is an invasive method; 2) analysis cannot be repeated on the same site; 3) it provides a limited understanding of the changes in the elasticity, microangiography, blood flow velocity and direction. Consequently, a myriad of non-invasive investigative techniques have been developed to aid tissue assessment.
Various tissue imaging modalities such as ultrasound imaging (2-4) and MRI (5; 6) are available and used for tissue characterisation. However, these techniques are known to lack accuracy in the quantitative information they provide due to low imaging resolution and mechanical sensitivity. Thus they have difficulties in differentiating and identifying early and subtle changes.
Optical coherence tomography is an emerging non-invasive assessment tool that overcomes many weaknesses inherent in other equivalent modalities and is free of side-effects (7; 8). It is a real-time tomographic imaging technique using low-intensity infrared light focused within living tissue. Interferometric detection of reflected light enables high-resolution, 2- or 3- dimensional, cross-sectional visualisation of tissue morphology analogous to histology. OCT provides depth-resolved images of tissues up to 3mm deep with a high lateral resolution.
The Functional OCT has been successfully used in a variety of clinical applications such as ophthalmology, dermatology and cardiology (5; 7; 8), and has huge potential in pharmaceutical and chemical development and as a tool for fundamental research. The system can provide high-resolution structural imaging as well as functional information on parameters such as stiffness change and microvascular structural change. It also allows for differentiation between small alterations in mechanical properties, for example between benign and early malignant tumours (9). It has a broad spectrum of applications for serial small animal imaging in areas such as developmental biology, tissue engineering and the development of new biocompatible materials.
Functional OCT is designed and developed through a collaboration between medical photonics groups at the University of Dundee and the University of Washington. We focus on state-of-the art, non-invasive and high resolution optical imaging systems for in vivo and real-time characterisation of tissue.
We are seeking partners interested in applying the system to their research. Partners would ideally have access to in vivo animal data and/or clinical models of developing or diseased tissue which is undergoing structural and functional change, e.g. in tissue engineering, diabetes or wound healing programs. Such collaborators could be large companies, biotechs, academics, or healthcare providers.
We would also welcome input and guidance from potential commercial partners to make our system more portable for various environments according to their needs.
The University has a flexible approach to the protection and exploitation of any foreground IP. It would look to derive benefit from the IP but if a partner company was best placed to develop the commercial route then the ownership or an exclusive licence to the technology would be agreed.
Refinement: Functional OCT can provide high resolution images of tissue in vivo, enabling ‘optical biopsy’ without taking a real piece of tissue. The quality of images from functional OCT can be as high as microscopy images and the tissue assessment can be tracked and studied continuously at a local level. Concrete diagnosis can be made earlier resulting in less suffering and shorter experimental times for the animal. The system also circumvents the need for more invasive tests such as vascular access and stiffness measurement by mechanical load.
Reduction: Functional OCT enables in vivo study on the same tissue site and thus can allow for a reduction in the number of animals necessary in future studies. This would also reduce the time required to complete the analysis if less samples have to be processed. Moreover, by having the ability to serially sample the same animal, the researcher can track an individual animal over time, allowing more complete data collection. Traditional approaches to generate this data require groups of animals to be sacrificed at multiple time points. The number of animals required is further reduced as the lack of inter-animal variation means that the standard deviation found with this non-invasive method is smaller than that associated with the current methods.
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