Oral [111In]DTPA scintigraphic assessment of colonic transit in constipated subjects

Patterns of colonic transit were assessed by a simple radioisotopic technique using 3.7 MBq of orally administered [111In]DTPA in 16 control subjects and 37 patients with intractable constipation. Normal subjects showed rapid diffuse spread of isotope through the colon resulting in low activity in all regions of interest (ROI). Activity was lost to feces at 24 hr and was virtually complete by 72 hr (median 94%, range 71-100%). Five constipated patients showed normal transit. Those with colonic inertia (N = 26) showed a significantly slowed geometric center of isotope compared to controls (P < 0.001), falling below the normal range at 48 hr. Percentage activity curves showed the major site of isotope hold-up to be in the transverse colon and splenic flexure. Other constipated patients (N = 6) showed late delay of the geometric center of isotope and accumulation of activity in the descending and rectosigmoid colon, compared to controls, at 96 hr. Oral [111In]DTPA colonic scintigraphy is a useful clinical test in the investigation of constipation.