OtherBasic Science Investigations

Reproducibility of 11C-Raclopride Binding in the Rat Brain Measured with the MicroPET R4: Effects of Scatter Correction and Tracer Specific Activity

David L. Alexoff, Paul Vaska, Douglas Marsteller, Timofei Gerasimov, Juan Li, Jean Logan, Joanna S. Fowler, Nicholas B. Taintor, Panayotis K. Thanos and Nora D. Volkow
Journal of Nuclear Medicine May 2003, 44 (5) 815-822;

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    Typical sinogram projections in rat head with 11C-raclopride. (A) Ten minutes after injection. (B) Sixty minutes after injection.

  • FIGURE 2.
    FIGURE 2.

    Test-retest experiments in rat brain with 11C-raclopride. For all graphs, circles represent striatum and diamonds represent cerebellum. %ID/cm3 = percentage of injected dose per cubic centimeter. • and ♦, First injection; ○ and ⋄, Second injection. (A) First injection, 12.84 MBq (347 μCi; 3.8 nmol/kg raclopride); second injection, 11.91 MBq (322 μCi; 1.9 nmol/kg raclopride). (B) First injection, 7.22 MBq (195 μCi; 1.2 nmol/kg raclopride); second injection, 6.51 MBq (176 μCi; 1.0 nmol/kg raclopride). (C) First injection, 5.99 MBq (162 μCi; 0.5 nmol/kg raclopride); second injection, 13.88 MBq (375 μCi; 1.7 nmol/kg raclopride). (D) Blocking study: first injection, 17.58 MBq (475 μCi; 15 nmol/kg raclopride); second injection, 18.54 MBq (501 μCi; 1 mg/kg or 2,881 nmol/kg raclopride).

  • FIGURE 3.
    FIGURE 3.

    Reproducibility of 11C-raclopride binding in brains of 6 adult rats. •, Mean ROI value in striatum in 6 rats. ♦, Mean ROI value in cerebellum of 6 rats. Error bars are ±1 SD of mean. %ID/cm3 = percentage of injected dose per cubic centimeter.

  • FIGURE 4.
    FIGURE 4.

    Effect of raclopride mass on DVR. Receptor occupancy is calculated from injected raclopride mass associated with tracer 11C-raclopride according to Hume et al. (23).

Tables

  • TABLE 1

    Effect of Scatter Correction on Image ROI Data

    StudyΔ (%) ROI
    Striatum*Cerebellum*
    ptvec4−4.7−21
    darat9−3.0−7.9
    darat8−5.5−15
    darat7−4.3−10
    darat6−4.9−16
    darat5−2.7−11
    darat4−2.6−11
    darat3−3.2−15
    darat2†−10†−12†
    darat1−5.4−10
    daptvec2−2.9−17

    • ↵* Sixty minutes after radiotracer injection.

    • ↵† Blocking study: 11C-raclopride coinjected with raclopride (1 mg/kg).

    • Δ = (ROIcorrected − ROIraw)/ROIraw × 100.

  • TABLE 2

    Effect of Scatter Correction on DVR

    StudyDVRDVRsc*% change†
    daptvec22.312.55+10
    ptvec42.392.52+5.4
    darat11.621.65+1.9
    darat21.201.23+2.5
    darat32.082.080
    darat41.901.97+3.7
    darat52.382.46+3.4
    darat62.562.62+2.3
    darat72.192.27+3.7
    darat82.292.35+2.6
    darat92.142.20+2.8

    • ↵* DVR after scatter correction.

    • ↵† (DVRsc − DVR)/DVR × 100.

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