A1 Journal article – refereed
Absorption, distribution and excretion of intravenously injected 68Ge/68Ga generator eluate in healthy rats, and estimation of human radiation dosimetry




List of Authors: Anu Autio, Helena Virtanen, Tuula Tolvanen, Heidi Liljenbäck, Vesa Oikonen, Tiina Saanijoki, Riikka Siitonen, Meeri Käkelä, Andrea Schüssele, Mika Teräs, Anne Roivainen
Publisher: SpringerOpen
Publication year: 2015
Journal: EJNMMI Research
Volume number: 5
Issue number: 40

Abstract


Background



This study evaluated the absorption, distribution, and excretion of Gallium-68 ( 68 Ga) radionuclide after a single intravenous (i.v.) injection of 68 Ge/ 68 Ga generator eluate in healthy rats. Additionally, human radiation doses were estimated from the rat data.



Methods



Twenty-one female and 21 male Sprague-Dawley rats were i.v. injected with 47 ± 4 MBq of 68 Ge/ 68 Ga generator eluate, and the radioactivity of excised organs was measured using a gamma counter at 5, 30, 60, 120, or 180 min afterwards (n = 3–7 for each time point). The radioactivity concentration and plasma pharmacokinetic parameters were calculated. Subsequently, the estimates for human radiation dosimetry were determined. Additionally, 4 female and 5 male rats were positron emission tomography (PET) imaged for in vivo visualization of biodistribution.



Results



68 Ga radioactivity was cleared relatively slowly from blood circulation and excreted into the urine, with some retention in the liver and spleen. Notably, the 68 Ga radioactivity in female genital organs, i.e., the uterus and ovaries, was considerable higher compared with male genitals. Extrapolating from the female and male rat 68 Ga data, the estimated effective dose was 0.0308 mSv/MBq for a 57-kg woman and 0.0191 mSv/MBq for a 70-kg man.



Conclusions



The estimated human radiation burden of the 68 Ge/ 68 Ga generator eluate was slightly higher for females and similar for males as compared with somatostatin receptor ligands 68 Ga-DOTANOC, 68 Ga-DOTATOC, and 68 Ga-DOTATATE, which is probably due to the retention in the liver and spleen. Our results revealed some differences between female and male rat data, which, at least in part, may be explained by the small sample size.




 

Last updated on 2019-21-08 at 22:26