Imaging

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Light-emitting ‘fluorophores’ are the key ingredient to the science behind Versicolour, our multi-colour imaging system.
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The Science

A big challenge faced by clinicians and scientists when trying to detect infection through direct imaging is being able to distinguish between the natural glow emitted by organ tissue (known as autofluorescence), and that emitted by any bacteria or pathogens that may be present. Often, autofluorescence can obscure the signals of interest if they glow at the same wavelength of light, and highlight other structures instead. This is where special compounds called fluorophores become vital.

Fluorophores are molecules, antibodies or genetically modified proteins that are artificially introduced to a biological system. Each fluorophore emits different wavelengths of light when exposed to a high-intensity light source, such as a laser, corresponding to different colours. By engineering the compounds to attach to specific biological targets, it is possible to make the target glow and thus stand out against any background signal that may be present. This multi-coloured emission is subsequently detected by an imaging system in a technique known as fluorescence microscopy.

Being able to distinguish between bacteria and other pathogens is the main driver of the Proteus project, in order to provide quicker and more accurate diagnoses. Thanks to our Versicolour system, we are able to currently detect red and green fluorescence simultaneously.

False colour images of an ex vivo human lung, taken with the Panoptes fibre and Versicolour imaging system. (L)  Lung tissue autofluorescence. (C) SmartProbe-labelled bacteria, using a fluorophore called merocyanine. (R) Combining the green and red channels, it is possible to see the labelled bacteria gathering along the strands of lung tissue. Image credit: Dominic Norberg (Proteus/OPTIMA)

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The System

Versicolour is our multi-colour imaging device, which, when combined with the Panoptes fibre bundle, will allow clinicians to see bacteria, inflammation and scarring in the lungs in real-time. Previously, it has only been possible to image in two colours. However, in 2015 Versicolour demonstrated a world-first of using thee-colour imaging to look inside a patient’s lungs at their bedside, using commercially available and affordable components.

The imaging is done via endoscopy, using our bespoke, medically-approved optical fibre that is fed through a traditional bronchoscope at one end and attached to the Versicolour device at the other. This is beneficial for clinicians as it is a non-invasive procedure common to many fields of medicine, which can relay important information for investigation of symptoms or confirmation of diagnosis. Light emitted from multiple LEDs is focused and combined into a singular beam before being sent through a mini microscope element within the fibre to the area of interest within the lung that has been sprayed with our ‘SmartProbe’ fluorophores. The reflected light is sent back through the microscope element and focused onto a camera with a fast CMOS (Complementary Metal-Oxide Semiconductor) sensor.

Versicolour has undergone multiple tests in a pre-clinical setting on ex vivo animal lungs and has repeatedly performed well in challenging experiments. We have demonstrated the effectiveness of the instrument by simultaneously imaging neutrophils (white blood cells that form the first line of defence against infection and inflammation), macrophages (white blood cells that consume invading pathogens and cell debris) and fungus in ex vivo human lung tissue, with excellent results.


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