Noninvasive evaluation of mucosal healing in inflammatory bowel diseases

Current opinions increasingly cite the need to achieve not only clinical response but also endoscopic mucosal healing in the treatment of both types of inflammatory bowel disease: ulcerative colitis (UC) and Crohn's disease (CD). Although endoscopic procedures are necessary for confirmation of mucosal healing, undergoing colonoscopy is invasive and burdensome to patients. Therefore, alternative noninvasive methods of evaluating or predicting mucosal status have been eagerly desired. For this purpose, blood, fecal, and radiologic modalities have been suggested and examined. C-reactive protein and fecal markers such as fecal calprotectin can evaluate active inflammation to some extent in both UC and CD. However, their predictive values for mucosal healing have not yet been fully evaluated and current knowledge indicates that the values were rather insufficient. Radiologic modalities such as computed tomography, magnetic resonance, and ultrasound can also evaluate mucosal inflammation but are currently not suitable for detection of healing. Capsule endoscopy may be optimal for evaluating mucosal status of the small bowel in CD patients, but sufficient data are not yet available, particularly for mucosal healing. Thus, these candidates for the surrogate modality are currently imperfect for evaluation of mucosal healing, but the changes in values/findings of these modalities after initiation of therapy appear to be rather promising as a marker of efficacy of the therapy. Finally, our recent data showed that a fecal immunochemical test for evaluation of mucosal healing in UC was very promising and this method should be further evaluated in CD also.