Segmental colonic transit after oral Ga-67-citrate in healthy subjects andthose with chronic idiopathic constipation

Measurement of segmental colonic transit is important in the assessment of patients with severe constipation. (111)ln-diethylenetriamine pentaacetic a cid (DTPA) has been established as the tracer of choice for these studies, but it is expensive and not readily available. Ga-67-citrate is an inexpens ive tracer and when given orally is not absorbed from the bower. It was com pared with (111)ln-DTPA in colonic transit studies in nonconstipated contro l subjects and then in patients with idiopathic constipation. Methods: Stud ies were performed after oral administration of 3 MBq (81 mu Ci) Ga-67-citr ate or 4 MBq (108 mu Ci) (111)ln-DTPA in solution. Serial abdominal images were performed up to 96 h postinjection, and computer data were generated f rom geometric mean images of segmental retention of tracer, mean activity p rofiles and a colonic tracer half-clearance time. Results: There were no di fferences in segmental retention of either tracer or in mean activity profi les between control subjects and constipated patients, Results in constipat ed subjects were significantly different from those in controls. The mean h alf-clearance times of tracer for control subjects were 28.8 h for Ga-67-ci trate and 29.9 h for (111)ln-DTPA in control subjects and 75.0 h for Ga-67- citrate and 70.8 h for (111)ln-DTPA in constipated patients. Conclusion: Or al Ga-67-citrate can be used as a safe alternative to (111)ln-DTPA for accu rate measurement of segmental colonic transit.