title: High specific activity [samarium-153] EDTA for imaging of experimental tumor models.
abstract: Enriched samarium oxide (98.2% 152Sm2O3) was irradiated in low neutron flux and high neutron flux reactors to produce 153Sm with specific activities of 14.3 GBq and 22.1 TBq mmol-1 Sm, respectively, at the time of use. Formulation of 153Sm as [153Sm]EDTA, with a 1:10 molar ratio of SM:EDTA, provided a stable radiotracer in vitro and in vivo. High specific activity [153Sm]EDTA showed superior uptake in cell culture (20.8 +/- 0.9% vs. 5.5 +/- 0.1% for 6 and 600 pmol Sm per 10(6) cells, respectively) and better tumor index values (51 vs. 37 at 10.9 nmol and 1.09 mumol Sm kg-1, respectively) in the BDF1 mouse/Lewis lung tumor model. High specific activity [153Sm]EDTA scintigrams of Copenhagen x Fisher rats bearing transplanted Dunning R3327 tumors clearly delineated the tumors within 6 hr, with moderate liver and bone uptake and low soft-tissue background. The injected radiotracer underwent rapid central compartment clearance and whole-body elimination. The absence of observed adverse histopathological toxicity combines with high image quality within 6 hr, to support the clinical tumor-imaging potential of this agent. Comparative studies with [67Ga]citrate at molar-equivalent doses indicated that high specific activity [153Sm]EDTA was a superior radiotracer in these in vitro and in vivo models.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada.
authors.forename: J W
authors.initials: JW
authors.lastname: Tse
authors.forename: L I
authors.initials: LI
authors.lastname: Wiebe
authors.forename: A A
authors.initials: AA
authors.lastname: Noujaim
mesh_terms: D000818:Animals; D002460:Cell Line; D002951:Citrates; D019343:Citric Acid; D004492:Edetic Acid / Q000493:pharmacokinetics; D066298:In Vitro Techniques; D007553:Isotope Labeling; D008297:Male; D051379:Mice; D009374:Neoplasms, Experimental / Q000000981:diagnostic imaging*; D011868:Radioisotopes; D011877:Radionuclide Imaging; D051381:Rats; D012493:Samarium; D014018:Tissue Distribution
chemical_list: D002951:Citrates; D011868:Radioisotopes; D019343:Citric Acid; D012493:Samarium; D004492:Edetic Acid