RT Journal Article SR Electronic T1 Parametric Imaging and Test–Retest Variability of 11C-(+)-PHNO Binding to D2/D3 Dopamine Receptors in Humans on the High-Resolution Research Tomograph PET Scanner JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 960 OP 966 DO 10.2967/jnumed.113.132928 VO 55 IS 6 A1 Gallezot, Jean-Dominique A1 Zheng, Ming-Qiang A1 Lim, Keunpoong A1 Lin, Shu-fei A1 Labaree, David A1 Matuskey, David A1 Huang, Yiyun A1 Ding, Yu-Shin A1 Carson, Richard E. A1 Malison, Robert T. YR 2014 UL http://jnm.snmjournals.org/content/55/6/960.abstract AB 11C-(+)-4-propyl-9-hydroxynaphthoxazine (11C-(+)-PHNO) is an agonist radioligand for imaging dopamine D2 and D3 receptors in the human brain with PET. In this study we evaluated the reproducibility of 11C-(+)-PHNO binding parameters using a within-day design and assessed parametric imaging methods. Methods: Repeated studies were performed in 8 subjects, with simultaneous measurement of the arterial input function and plasma free fraction. Two 11C-(+)-PHNO scans for the same subject were separated by 5.4 ± 0.7 h. After compartment models were evaluated, 11C-(+)-PHNO volumes of distribution (VT) and binding potentials relative to the concentration of tracer in plasma (BPP), nondisplaceable tracer in tissue (BPND), and free tracer in tissue (BPF) were quantified using the multilinear analysis MA1 method, with the cerebellum as the reference region. Parametric images of BPND were also computed using the simplified reference tissue model (SRTM) and SRTM2. Results: The test–retest variability of 11C-(+)-PHNO BPND was 9% in D2-rich regions (caudate and putamen). Among D3-rich regions, variability was low in the pallidum (6%) but higher in substantia nigra (19%), thalamus (14%), and hypothalamus (21%). No significant mass carry-over effect was observed in D3-rich regions, although a trend in BPND was present in the substantia nigra (−14% ± 15%). Because of the relatively fast kinetics, low-noise BPND parametric images were obtained with both SRTM and SRTM2 without spatial smoothing. Conclusion: 11C-(+)-PHNO can be used to compute low-noise parametric images in both D2- and D3-rich regions in humans.