TY - JOUR T1 - Optimal Duration of PET Studies with <sup>18</sup>F-Fluoroethyl-Diprenorphine JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 2092 LP - 2096 VL - 46 IS - 12 AU - Henning Boecker AU - Till Sprenger AU - Gjermund Henriksen AU - Thomas R. Toelle AU - Mary E. Spilker Y1 - 2005/12/01 UR - http://jnm.snmjournals.org/content/46/12/2092.abstract N2 - The tracer 6-O-(2-18F-fluoroethyl)-6-O-desmethyldiprenorphine (18F-FDPN) provides enhanced flexibility to PET studies of the opioidergic system because the label has a longer half-life than the label of 11C-diprenorphine. Here we evaluated the ideal length of PET studies with 18F-FDPN. Methods: 18F-FDPN binding kinetics were quantified with protocols of different lengths by use of a 1-tissue or a 2-tissue compartment model for different volumes of interest. Furthermore, the effects of scanning duration were assessed by parametric analyses. Results: A 90-min protocol resulted in less than 10% bias in distribution volume (DV) relative to the full-length protocol. Correlation analyses of the DV estimates for the full-length protocol and the shortened protocols showed good replication of DV estimates for regions with both low and high levels of binding at schedules of up to 90 min. Conclusion: Data sampling in dynamic 18F-FDPN PET acquisitions should not be shorter than 90 min to maintain reliable estimates of DV. ER -