Use of technegas as a radiopharmaceutical for the measurement of gastric emptying

Many radiopharmaceuticals and test meals that are used to measure gastric emptying are less than optimal. A vegetable-based solid meal, such as rice, labelled with a radiopharmaceutical that also has the capacity to measure gastric emptying of liquids, is likely to be ideal. The role of Technegas as a radioisotopic marker to measure gastric emptying of rice and liquids was evaluated. Technegas-labelled rice was incubated in 0.9% saline, 1 M HCl and simulated gastric fluid (3.2 g/l pepsinogen, pH 2-3) to assess stability of the label. In eight healthy volunteers gastric emptying of two meals - 200 g rice (370 kcal) and 75 g dextrose dissolved in 300 ml water (300 kcal), both labelled with 20 MBq of Technegas - was measured scintigraphically. Over 4 h, the average label stability was 93.7%±0.5% in 0.9% saline, 91.0%±0.4% in 1 M HCl and 93.6%±0.7% in simulated gastric juice. The lag phase was longer for rice than dextrose (25±7 min vs 4±2 min; P<0.05), but there was no difference in the post-lag emptying rate (2.1±0.3 kcal/min vs 1.7±0.2 kcal/min; P=0.2) between the two meals. We conclude that Technegas is a suitable radiopharmaceutical for measurement of gastric emptying of rice and nutrient-containing liquids. (orig.)