title: Gallium-67 complexes as radioactive markers to assess gastric and colonic transit.
abstract: Constipation and gastroparesis are gastrointestinal tract disorders that can be assessed by using radioactive markers in conjunction with scintigraphic techniques. Indium-111-DTPA is the radiopharmaceutical of choice for treating colonic transit in constipated patients, but it is an expensive product and its availability has been unreliable. Indium-113m-DTPA was the tracer used in our study to determine the liquid gastric emptying rate in dual-isotope solid/liquid emptying studies, however, cessation of the 113Sn/113mIn generator production makes it unavailable. Thus, development of alternative tracers to 111In-DTPA and 113mIn-DTPA was essential.
  
  
  METHODS
  Gallium-67-citrate and 67-Ga-EDTA were compared to 111In-DTPA to assess their efficacy for exclusive retention in the Gl tract. These markers were orally administered into rats and their three-day cumulative fecal excretion, urine excretion and carcass retention were measured. An in vitro gastric emptying model was used to determine liquid phase partitioning of 113mIn-DTPA, 67Ga-citrate and 67Ga-EDTA at 37 degrees.
  
  
  RESULTS
  Gallium-67-citrate was predominantly excreted in the feces (97.2% +/- 0.2%) after three days, with negligible urine excretion (0.1% +/- 0.0%) and carcass retention (0.6% +/- 0.2%). These results are analogous to those obtained for 111In-DTPA for fecal excretion (96.7% +/- 2.6%), urine excretion (0.6% +/- 0.0%) and retention in the carcass (0.2% +/- 0.0%). Gallium-67-EDTA showed similar partitioning in the liquid phase of the gastric emptying model compared with 113mIn-DTPA.
  
  
  CONCLUSIONS
  Gallium-67-citrate is an economical and readily available alternative to 111In-DTPA as a colonic transit radiopharmaceutical. Gallium-67-EDTA is also an alternative to 113mIn-DTPA for assessing liquid-phase emptying in a dual-isotope solid/liquid gastric emptying study.
authors.affiliation: Nuclear Medicine Department, Royal Adelaide Hospital, Australia.
authors.forename: J C
authors.initials: JC
authors.lastname: Bellen
authors.forename: B E
authors.initials: BE
authors.lastname: Chatterton
authors.forename: S
authors.initials: S
authors.lastname: Penglis
authors.forename: C
authors.initials: C
authors.lastname: Tsopelas
mesh_terms: D000818:Animals; D003106:Colon / Q000502:physiology*; D005260:Female; D005710:Gallium Radioisotopes; D005746:Gastric Emptying / Q000502:physiology*; D005772:Gastrointestinal Transit / Q000502:physiology*; D051381:Rats
chemical_list: D005710:Gallium Radioisotopes