TECHNIQUES AND ERRORS IN SCINTIGRAPHIC MEASUREMENTS OF GASTRIC-EMPTYING

Abstract

For the monitoring of gastric emptying, a gamma camera or scanner operating from 1 side of the patient is subject to variations of counting efficiency due to the changing depth of radioactivity. A double-headed scanner was used to investigate the effects of such changes. Tc-99m and In-113m were used as labels for the solid and liquid components of a meal. The depth of Tc-99m within the stomach decreased by a mean of 13 mm during the 1st 1/2 h of emptying. Anterior detection alone underestimated emptying rates by an average of 26%. Depth changes also introduced errors into early emptying measurements made unilaterally. Such artifacts of measurement may compromise mathematical analyses of emptying patterns.