Introduction Colonoscopic assessment after post-operative resection and re-anastomosis for Crohn’s disease (CD) is an accepted part of the routine follow-up of such patients. Anastomotic ulcers (figure) are a relatively frequent observation and may be misinterpreted as recurrent CD, thus incurring the need and cost of biopsy examination. Autofluorescence imaging (AFI) technology detects the wavelengths of light emitted by endogenous molecules (fluorophores; such as NAD, FAD), corresponding to their concentration, metabolic state and spatial distribution¹. In tissue with a high metabolic rate or under oxidative stress (inflammation or dysplasia), AFI generates a purple colouration, compared to green when normal tissue is imaged. We hypothesised that AFI might discriminate between appearances due to anastomotic ulceration and CD recurrence.

Method Patients at our Institution undergoing per-protocol colonoscopy as part of routine post-operative evaluation of CD were examined with the AFI colonoscope (Olympus CF-FH260AZL and either 260 or 290 series processor) by three consultant Endoscopists familiar with AFI technology. The Endoscopists’ opinion as to whether the endoscopic appearance was most in keeping with anastomotic ulceration, with mostly fixed purple (AFI+) or green (AFI-) fluorescence was recorded and compared to eventual histology results. As the measurement of faecal calprotectin (FCALP) is also protocolised post-operatively, we were also able to take into account this well-validated marker.

Results 10 patients were examined with AFI. 4 were AFI+ and all were confirmed as having histologic evidence of IBD. 5 were AFI- and again all were confirmed by histologic examination. 1 patient had equivocal changes on AFI and biopsies excluded recurrent CD. Faecal calprotectin was <100 mcg/g at 3 and 6 months post-operatively 5/6 patients in whom AFI was normal or equivocal, and elevated at 6 months >100 in all 4 patients AFI+.

Conclusion Although a small cohort, our results indicate that AFI may be highly discriminatory and suggests potential new applications for this technology: combining non-invasive markers and findings on AFI, NBI and magnification might obviate the need for biopsy to exclude disease recurrence; the degree and extent of mucosal inflammation could be assessed; dysplasia could more readily be detected. Further prospective studies are planned to determine and establish the role of AFI in IBD. Use of the 290 series processor with this technology may improve detection and discrimination.

Disclosure of interest None Declared.

Reference

1. ASGE technology assessment. Gastrointest Endosc 2011;73:647–50