Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The extend of burden and risk associated with participation is negligible. Using DF imaging on the bowel is a non-invasive technique requiring a minimal amount of time as is described in the study procedure. Previous studies did not show any safety concerns. Measuring will be performed under sterile conditions and the occurrence of tissue damage is highly unlikely. Patients are under general anesthesia and will thus not experience any inconvenience.