Reference values for the geometric centre analysis of colonic transit measurements with 111indium-labelled diethylenetriamine penta-acetic acid.

The geometric centre analysis is often used for evaluating colonic transit data obtained by scintigraphy after oral intake of 111indium-labelled diethylenetriamine penta-acetic acid (111In-DTPA). The purpose of this study was to establish reference values for the geometric centre analysis in adult humans. Forty-eight healthy volunteers (24 women, 24 men) who were equally distributed among three age groups (young, middle-aged, elderly) were studied. In all subjects the geometric centre of radioactivity in the colon was calculated from abdominal gamma camera images acquired 24, 48, 72, and 96 h after oral administration of 111In-DTPA. Overall, the men had a higher geometric centre value than women after both 24 and 48 h indicating a faster progress of colonic contents in men at these time points. At each time point the geometric centre value was higher in both the young and middle-aged subjects than in the elderly subjects, whereas we did not find any difference between young and middle-aged subjects. Furthermore, the smokers had a higher geometric centre value than non-smokers at each time point. The geometric centre value was not influenced by body mass index at any time point.