Research ArticleNeurology

Head-to-Head Comparison of 11C-PBR28 and 18F-GE180 for Quantification of the Translocator Protein in the Human Brain

Paolo Zanotti-Fregonara, Belen Pascual, Gaia Rizzo, Meixiang Yu, Neha Pal, David Beers, Randall Carter, Stanley H. Appel, Nazem Atassi and Joseph C. Masdeu
Journal of Nuclear Medicine August 2018, 59 (8) 1260-1266; DOI: https://doi.org/10.2967/jnumed.117.203109

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    SUV concentrations of parent compound (green lines) and whole blood (red lines) for 11C-PBR28 (A) and 18F-GE180 (B) in representative subject. Although parent concentration of 11C-PBR28 is generally lower than whole-blood concentration, opposite is true for 18F-GE180. (C) Average and SD from all subjects of parent fraction in plasma for 11C-PBR28 (dashed line) and 18F-GE180 (solid line). Metabolism rate is much slower for 18F-GE180, as parent constitutes about 70%–80% of total plasma activity at end of 90-min scan.

  • FIGURE 2.
    FIGURE 2.

    Time–activity curves, expressed in SUVs, of 3 representative regions from right hemisphere of brain of healthy volunteer with high-affinity binding. (A) Temporal cortex. (B) Putamen. (C) Cerebellum. SUVs of 18F-GE180 curves (○) were substantially lower (peak value of <1) than those of 11C-PBR28 curves (●) (peak value of >2), and curves were almost flat. Lines represented fitting by 2-tissue-compartment model.

  • FIGURE 3.
    FIGURE 3.

    Parametric images of 11C-PBR28 and 18F-GE180, obtained with Logan plot, for healthy volunteer with high-affinity binding and corresponding MR images for anatomic reference. 18F-GE180 had very low uptake in brain; therefore, vascular structures are prominently visible.

Tables

  • TABLE 1

    Comparison of Kinetic Modeling Parameters for 11C-PBR28 and 18F-GE180 Using 2-Tissue-Compartment Model

    K1 (mL ⋅ cm−3 ⋅ min−1)VT (mL ⋅ cm−3)
    Region*11C-PBR2818F-GE18011C-PBR2818F-GE180
    Superior frontal cortex0.090 ± 0.012 (2.0)0.0066 ± 0.0006 (5.4)3.22 ± 0.69 (2.1)0.15 ± 0.03 (6.3)
    Temporal cortex0.096 ± 0.013 (2.3)0.0070 ± 0.0006 (5.6)3.21 ± 0.75 (2.1)0.15 ± 0.02 (3.4)
    Parietal cortex0.085 ± 0.012 (2.8)0.0082 ± 0.0023 (9.6)3.04 ± 0.70 (3.0)0.14 ± 0.04 (3.8)
    Cerebellum0.115 ± 0.014 (1.8)0.0077 ± 0.0011 (11.7)3.30 ± 0.70 (2.2)0.16 ± 0.05 (10.7)
    Average0.094 ± 0.017 (3.5)0.0070 ± 0.0016 (14.7)3.27 ± 0.66 (4.0)0.15 ± 0.03 (7.0)

    • ↵* Representative brain regions from right hemisphere.

    • Values are reported as mean ± SD. Average SEs are shown in parentheses and are expressed as percentages of variables.

  • TABLE 2

    Comparison of Brain Exposures for 11C-PBR28, 18F-GE180, and 5 Other Radioligands

    Parameter11C-PBR2818F-GE18011C-LY2428703 (28)18F-FMPEP-d2 (30)18F-SP203 (50)11C-(R)-rolipram (31)11C-NOP-1A (32)
    TargetTSPOTSPOmGluR1CB1mGluR5PDE4NOP
    Brain SUVpeak∼2∼0.7∼0.53–4∼62–2.55–7
    Exposure SUV (0–20 min)41.1169.8202.247.837.0124.936.7
    fp (%)4.13.50.0940.635.26.410.1
    Effective exposure*1.75.90.190.301.98.03.7

    • ↵* Area under curve of input function during first 20 min multiplied by free fraction.

    • mGluR1 = metabotropic glutamate receptor 1; CB1 = cannabinoid receptors type 1; mGluR5 = metabotropic glutamate receptor 5; PDE4 = phosphodiesterase 4; NOP = nociceptin/orphanin FQ peptide.

    • Brain exposure for 11C-PBR28 and 18F-GE180, compared with that of the 5 other radioligands analyzed in Zanotti-Fregonara (28).

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