Using a dual-headed gamma camera and a standardized egg test meal labeled with 99mTc-sulfur colloid, the quantitative emptying of the total, proximal and distal stomach in five normal subjects was characterized. The same egg meal was given to the volunteers in 3 different forms: homogenized, and as 2.5 mm and 5.0 mm cubes on 3 separate occasions for a total of 15 studies. For the total stomach emptying, the lag phase and half emptying time (T1/2) obtained using a power exponential model were significantly shorter for the homogenized test meal than for the 2.5 mm and 5.0 mm cubed egg particles; the lag phases were 29 +/- 19 min (mean +/- SD) vs 55 +/- 26 (P less than 0.05) and 64 +/- 24 min (P less than 0.01), the T1/2's were 71 +/- 30 min vs 91 +/- 26 (P less than 0.05) and 104 +/- 30 min (P less than 0.05), respectively. For the proximal stomach, no statistically significant difference was observed among the 3 test meals; the T1/2s for the homogenized, 2.5 mm and 5.0 mm cubed meals were 65 +/- 26 min, 53 +/- 18 min and 64 +/- 20 min, respectively. For the distal stomach, both the peak activity (%) and time to peak activity (min) were significantly higher for the 2.5 mm cubes (43%, 54 min) and the 5.0 mm cubes (38%, 60 min) than for the homogenized eggs (16.4%, 30 min) (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)