Gastric emptying of a radionuclide-labeled test meal in healthy dogs: a new mathematical analysis and reference values.

The gastric retention of a semisolid meal, labeled with 99mTc, was measured in 27 clinically healthy dogs, using a gamma camera coupled to a data acquisition and analysis system. A new mathematical analysis was introduced describing the retention (Q [t]) of a unit meal as a function of time (t), as follows: Q (t) = [1-(alpha/p)t]p Where alpha and p are fitting variables. The rate of gastric emptying depends strongly on the variable alpha. The shape of the retention pattern is influenced by the variable p, particularly by the value of 1-1/p (median, 0.51). The description includes the exponential and the linear model. Initial half-time (median, 87 minutes), real half-time (median, 66 minutes), and 95% emptying time (median, 148 minutes) were determined from alpha and p, the latter being obtained from computer fitting Q (t) to the data. A wide variation of the values between the dogs was observed. Initial half-time and the value of 1-1/p varied strongly in the individual dogs, but the real half-time was reproducible (r = 0.85, P less than 0.01, 10 dogs).