Introduction In-vivo characterisation of small colonic polyps has been reported using several technologies but with few prospective comparisons between them. We aimed to compare the accuracy of Flexible Spectral Imaging Colour Enhancement (FICE) and i-Scan in the assessment of polyps < 10mm. In addition the relationship between accuracy of white light assessment (WL) and resolution of endoscope was assessed.

Methods Patients undergoing screening colonoscopy through the UK BCSP were prospectively recruited. All procedures were performed by a single endoscopist with extensive experience in in-vivo diagnosis. For the FICE group Fujinon 410,000 pixel CCD and 650,000 pixel CCD colonoscopes were used with an EPX 4400 processor. For the i-Scan group Pentax 1.2 Megapixel colonoscopes were used with an EPKi processor. All polyps < 10mm were assessed sequentially using white light endoscopy (WL) and either FICE or i-Scan before resection. Predicted histology was recorded with both modalities and compared to the final histopathological diagnosis. In-vivo characterisation accuracy was analysed based on the resolution of the endoscopes used; standard definition - SD (410K pixel), high definition – HD (650K pixel) and HD+ (1.2M pixel).

Results In the FICE group 293 polyps of mean size 4.7mm were assessed in 170 patients. In the i-Scan group 209 polyps of mean size 4.3mm were assessed in 84 patients. There was no significant difference in WL accuracy between SD and HD endoscopes (70% vs 72.7%, p = 0.606), however accuracy was significantly higher with the HD+ 1.2megapixel CCD endoscopes (93.3%) compared to both the SD (70.0%, p = 0.0001) and HD (72.7%, p = 0.0001) endoscopes. Sensitivity was significantly greater with FICE using an HD endoscope compared to an SD endoscope (92.6% vs 83.3%, p = 0.048). Overall accuracy was significantly greater with HD+ i-Scan (94.7%) than SD FICE (82.7%, p = 0.0003) and HD FICE (88.8%, p = 0.0439). The use of FICE improved accuracy from 70.0% with WL to 82.7% (p = 0.014) and from 72.7% with WL to 88.8% (p < 0.001) for SD and HD endoscopes respectively. Only a minor gain over WL was seen with addition of iScan (93.3% to 94.7%, p = 0.68).

Conclusion

1. Only a small, non-significant gain in WL accuracy is seen between a 410K pixel SD endoscope and a 650K pixel HD endoscope. However diagnostic accuracy with WL improves significantly with a 1.2 megapixel endoscope.

2. FICE significantly improves accuracy when used with an SD or HD endoscope but the very high WL accuracy of a 1.2 megapixel endoscope allows no significant additional improvement with i-Scan.

Disclosure of Interest None Declared.