Colonoscopies are the regarded the ‘gold standard’ for identifying bowel cancer early but can miss up to 20 per cent of precancerous cells.
Now, a photonic device is being developed to provide a cellular level view of the colon in real time, which will allow doctors to give an immediate diagnosis. Instigated by the pan-European PROSCOPE consortium, the aim is to develop a platform consisting of a backend system and optical probe heads that are compatible with endoscopes.
When examining polyps – clusters of cells that form along the ridges of the colon that could go on to develop cancer – doctors can miss a precancerous growth. When polyps are smaller than 10 mm in diameter, multiple in number, or flat in appearance, they are often associated with a higher miss rate.
Fitted to an endoscope, the new optical imaging system will give clinicians the power to zoom in on areas of the intestine identified for inspection. Building up detailed 3D images, the new device uses light to make a more detailed examination ‘at incredible speeds’.
According to project coordinator Peter Andersen, the imaging procedure starts with conventional white light to identify a suspicious area. Next, the device can zoom into the depth of the lesion using optical coherence tomography (OCT) first, then multi-photon microscopy for metabolic information as cancerous cells have a higher metabolism than adjacent, non-cancerous cells. Finally, Raman spectroscopy provides molecular information to assess the suspected lesion. Switching across the different modalities allows a doctor to look deeper and analyse the tissue further.
Andersen, a member of DTU Health Tech at the Technical University of Denmark, told The Engineer that the main challenge in integrating all modalities into a single probe head are related to differences in excitation wavelengths for the three methods, different numerical apertures, and different light detection geometries requiring careful optical and mechanical design under the space constraints of current endoscopes without compromising image quality.
“For the intended use, we plan to operate optical coherence tomography, including angiography, and Raman spectroscopy integrated into one probe, and a second probe devoted to multi-photon lightsheet microscopy,” he added. “They will be deployed simultaneously via two working channels in the endoscope, which will allow us to verify the clinical impact of each of the modalities and their combination. Designs for integration of all modalities are considered, but they will not be pursued at this stage of PROSCOPE.”
For now, Andersen said, the immediate focus is developing the optical probes and the backend system, system control software, and visualisation tools, and then to demonstrate feasibility in clinical tests.
"After reaching this milestone, allowing us to collect larger data sets, we plan to provide additional information displayed immediately to the clinician assisting their assessment, which would involve deep learning," he added.
Clinical testing in human patients is planned for the second part of 2023. Concluding in 2024, the four-year PROSCOPE project received a grant of €6m Horizon 2020 under the Research and Innovation action funding scheme.
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