RT Journal Article
SR Electronic
T1 Kinetic Analysis and Quantification of the Dopamine Transporter in the Nonhuman Primate Brain with <sup>11</sup>C-PE2I and <sup>18</sup>F-FE-PE2I
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 132
OP 139
DO 10.2967/jnumed.110.077651
VO 52
IS 1
A1 Andrea Varrone
A1 Miklós Tóth
A1 Carsten Steiger
A1 Akihiro Takano
A1 Denis Guilloteau
A1 Masanori Ichise
A1 Balázs Gulyás
A1 Christer Halldin
YR 2011
UL http://jnm.snmjournals.org/content/52/1/132.abstract
AB 18F-(E)-N-(3-iodoprop-2-enyl)-2β-carbofluoroethoxy-3β- (4′-methyl-phenyl)nortropane (18F-FE-PE2I) is a novel radioligand for dopamine transporter (DAT) PET. As compared with 11C-N-(3-iodoprop-2E-enyl)-2β-carbomethoxy-3β-(4-methylphenyl)nortropane (11C-PE2I), 18F-FE-PE2I shows faster kinetics and more favorable metabolism, with less production of a radiometabolite with intermediate lipophilicity (M1), which—in the case of 11C-PE2I—has been shown to enter the rat brain. In this study, we compared DAT quantification with 11C-PE2I and 18F-FE-PE2I in nonhuman primates, using kinetic and graphical analysis with the input function of both the parent and the radiometabolite, to assess the potential contribution of the radiometabolite. Methods: Three rhesus monkeys were examined with 11C-PE2I and 18F-FE-PE2I using the HRRT system. Arterial input functions of the parent and radiometabolite M1 were measured. Kinetic and graphical analyses were applied using either the parent input (methods 1 and 3) or the parent plus radiometabolite input (methods 2 and 4). Outcome measures were distribution volumes (VT and VND), specific-to-nondisplaceable tissue radioactivity ratio at equilibrium (BPND; parent input), and specific–to–nondisplaceable tissue radioactivity ratio at equilibrium in the presence of metabolites (RT; parent plus radiometabolite input). Results: 11C-PE2I showed higher distribution volumes than 18F-FE-PE2I calculated with methods 1 and 3 (striatal VT, ∼300%; VND in cerebellum, ∼30%). With methods 2 and 4, VT in the striatum was approximately 60% higher in the case of 11C-PE2I, whereas no difference in VND was found in the cerebellum. For each radioligand, BPND estimated with methods 1 and 3 tended to be higher than RT estimated with methods 2 and 4. However, the bias of BPND, compared with RT, was much larger for 11C-PE2I (40%–60% in the caudate and putamen) than for 18F-FE-PE2I (&lt;10% in the caudate and putamen). Conclusion: The direct comparison between the radioligands confirmed that 18F-FE-PE2I shows faster kinetics and more favorable metabolism than 11C-PE2I. The kinetic and graphical analyses with the input function of the parent and radiometabolite showed that the bias in BPND was much lower for 18F-FE-PE2I than for 11C-PE2I and suggested that the lower production of the radiometabolite M1 would make 18F-FE-PE2I more suitable for the DAT quantification. Further studies in humans are necessary to confirm these findings.