Multispectral imaging represents an exciting new field of investigation in endoscopic research. Multispectral imaging uses a specialised camera to detect multiple colours, allowing us to build a rough spectrum from each point in our image. It is widely reported that these spectra are different for different tissue types, but this is difficult to study ex vivo since de-oxygenation of the blood and decay of the tissue change these spectra considerably.

The investigators have therefore designed this study to asses the different multispectral imaging spectra of Barrett's Oesophagus, which we believe might be utilised as a method to detect dysplasia in the future.

The investigators have developed a custom multispectral endoscopes based around a CE marked device, the PolyScope disposable endoscope (PolyDiagnost). This is a combined sterile catheter and fibre optic device designed to optimize light delivery to the anatomy and to acquire and transmit endoscopic images back to a camera. This CE marked system can be used to endoscope luminal organs such as the oesophagus, but also biliary tract, the bladder and the oro-pharynx.

The PolyScope can be inserted thought the accessory channel of commercial endoscopes. The design of the fibre optic device is durable and re-useable; it is inserted within the disposable sterile catheter channel, which is able to flex and bend to orient the device to the region of interest for imaging. The fibre optic device never comes into contact with the patient. The sterile catheter, which shields the fibre optic device, is disposed following a procedure.

The use of the PolyScope provides the advantage of building on a known system. The commercial PolyScope probe is coupled outside of the patient to a custom multispectral detection and illumination system. No modified part of the device comes into contact with the patient.

The patients recruited to this study will have a clinical indication to an endoscopic examination for Barrett's oesophagus or early oesophageal adenocarcinoma. There will not be extra procedures involved. The experimental part of the procedure, using Polyscope multispectral endoscope will prolong the procedure in most cases by approximately 5-10 minutes

Inclusion Criteria:

• Male or female subjects over 18 years
• Previous diagnosis of Barrett's oesophagus, with an endoscopic length of at least 2 cm
• Previous diagnosis of oesophageal glandular dysplasia or early oesophageal adenocarcinoma for consideration of endoscopic therapy

Exclusion Criteria:

• History of oesophageal stricture precluding passage of the endoscope,
• Pregnancy, or planned pregnancy during the course of the study,
• Currently breastfeeding
• Any history of esophageal varices, liver impairment of moderate or worse severity (Child's- Pugh class B & C) or evidence of varices on initial treatment endoscopy,
• Any history of oesophageal surgery, except for uncomplicated fundoplication, and,
• History of coagulopathy, with INR>1.3 and/or platelet count of <75,000.
• On clopidogrel, and/or warfarin for high risk condition and unable to withhold temporarily the medication.