Hypothesis: The investigators hypothesize that more than 50% of the patients receiving enteric contrast material (ECM) < 2 hours of anesthesia/sedation would have residual gastric fluid volume (GFV) > 0.4 ml/kg. The investigators also hypothesize that measuring GFV by using region of interest in the CT technique is accurate compared to blind aspiration of the gastric contents with a syringe and a multi-orificed orogastric tube.