The relationship between technetium 99m pertechnetate gastric scanning and gastric contents

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Abstract
To elucidate the gastric handling of 99mTc, scintiscanning was performed under basal and stimulated conditions while simultaneously monitoring gastric outputs of water and Na, H+ and 99mTc pertechnetate ions in 6 healthy fasting volunteers. Gastric scintiscanning correlated well with gastric luminal 99mTc activity (r = 0.99). However, clearance of 99mTc from plasma into the gastric lumen showed only a poor correlation with H+ output (r = 0.68) and no correlation with Na output. Explanation of these results on a cellular basis can be achieved by assuming a 2-component mechanism for 99mTc secretion, with both the parietal cells (H+ ion secretory) and nonparietal cells (Na+ ion secretory) contributing to 99mTc gastric output. The relative contribution of each cell type to total 99mTc secretion is dependent on the degree of gastric stimulation, with nonparietal 99mTc secretion dominating in the basal state and parietal 99mTc secretion dominating in the stimulated state. Gastric scintiscanning with 99mTc pertechnetate should therefore stand only as an empirical test of gastric function and not as a means of measuring acid output.