About ml of oral contrast agent barium sulfate was administered immediately before injection of 18 F-FDG. The FDG uptake of intestines was analyzed by visual and semi-quantitative method on transaxial, coronal and saggital planes. A visual analysis of available non-attenuation corrected PET images of 27 matched regions revealed no contrast -related artifact. The clinical significance of this bias has not been established. Mukofalk was administered during a time period of 1.