Evaluation of gastric emptying by a simple isotope technique. A methodological study in the dog.

The gastric emptying of a fluid standard meal labelled with 99mTc-DTPA has been studied in dogs, using a scintillation detector. The method was assessed in a series of in vivo and in vitro experiments. The gastric emptying patterns were visualized as time-activity curves. In the initial phase, the typical curves showed a rapid emptying within 2-5 min after start of the meal, followed by a more varied emptying and a subsequent steady emptying in the basic phase. Duplicate tests showed acceptable reproducibility. The initial emptying varied among individuals, whereas the basic emptying did not vary significantly. Combined evacuation/isotope gastric emptying studies showed that the external counting technique produced results comparable to those obtained by evacuation. Short-lasting spikes and plateau-like dislocations were observed in the curves, indicating peristalsis and duodenogastric reflux, respectively. The observed data are comparable with those obtained in man when using a gamma camera. Gastric emptying tests, carried out during continuous infusion of distilled water, 20% soya bean oil, or 25% glucose into various parts of the proximal gastrointestinal tract, showed that in dogs inhibitory 'receptors' for fat and glucose were located in the small intestine distal to the ligament of Treitz.