Use of geometric center and parametric images in scintigraphic colonic transit studies

Scintigraphic studies give detailed information on colonic transit. In this study, several methods of presenting such data were compared and discussed. The aim of the study was to evaluate the role of geometric center (GC) and parametric images in interpretation of colonic transit studies.

Segmental colonic transit was measured in 117 patients: 50 with constipation, 24 with irritable bowel syndrome, 22 with fecal incontinence, 14 who were postsurgery, and 7 normal volunteers. 111In-labeled resin was administered in a pH-sensitive capsule, and images were acquired for 3 days. The percentage of activity in four regions of colon and in the feces was measured.

Five patterns of colonic transit were identified (16 rapid transit, 48 intermediate, 14 generalized delay, 5 left-sided delay, and 34 right-sided delay). The geometric center (sum of fraction of activity x region number) was calculated at each time point. Using the geometric center, the groups could be differentiated (P < 0.01) except for those with left-sided delay. In individual patients, patterns of colonic transit could not be determined using the geometric center alone. Gray-scale presentation of percent activity in each region (parametric images) allowed patterns of colonic transit to be identified in individuals.

Use of the geometric center is suitable for comparison of groups of patients, whereas parametric images identify patterns in individual patients.