Gastric emptying in normal subjects--a reproducible technique using a single scintillation camera and computer system.

The gastric emptying of a mixed solid and liquid meal was assessed in 24 normal subjects using a single camera/computer system which allowed continuous monitoring of both solids and liquids. It was shown that variation in tissue attenuation caused by the changing depth of radionuclide within the stomach accounted for large errors in the measurement of gastric emptying (alteration in 50% emptying time of up to 65%). A technique for the correction of attenuation is described which used factors derived from a lateral image of the stomach. In all subjects, solid emptying was slower than liquid emptying and was characterised by a delay (lag period) which was followed by linear emptying. Liquid emptying usually followed a single exponential pattern. The effect of physiological changes induced by increasing the calorie content of the liquid component of the meal was assessed by giving either water, 10% dextrose or 25% dextrose. Liquid emptying was slowed and the lag period of solid was prolonged as the calorie content increased. Reproducibility was assessed in 19 subjects. For the three groups studied (water, 10% dextrose, 25% dextrose) the day-to-day variation in gastric emptying was not significant for any measured parameter, while statistically significant differences were present in solid and liquid emptying between subjects and groups.