Whole-Body Distribution and Radiation Dosimetry of 11C-Elacridar and 11C-Tariquidar in Humans.

Abstract

(11)C-elacridar and (11)C-tariquidar are new PET tracers to assess the transport activity of P-glycoprotein (adenosine triphosphate-binding cassette subfamily B, member 1 [ABCB1]) and breast cancer resistance protein (adenosine triphosphate-binding cassette subfamily G, member 2 [ABCG2]). This study investigated the whole-body distribution and radiation dosimetry of both radiotracers in humans. Twelve healthy volunteers (6 women, 6 men) underwent whole-body PET/CT imaging over the 90 min after injection of either (11)C-elacridar or (11)C-tariquidar. Radiation doses were calculated with OLINDA/EXM software using adult reference phantoms. Biodistribution was consistent with a major elimination route of hepatobiliary excretion, which may be mediated by ABCB1 and ABCG2. High radioactivity uptake was seen in liver, followed by spleen and kidneys, whereas brain uptake was lowest. Effective doses were 3.41 ± 0.06 μSv/MBq for (11)C-elacidar and 3.62 ± 0.11 μSv/MBq for (11)C-tariquidar. Our data indicate that both (11)C-elacridar and (11)C-tariquidar are safe radiotracers, for which an injected activity of 400 MBq corresponds to a total effective dose of approximately 1.5 mSv.