OtherBasic Science Investigations

Quantification of Serotonin Transporters in Nonhuman Primates Using [123I]ADAM and SPECT

Paul D. Acton, Seok-Rye Choi, Catherine Hou, Karl Plössl and Hank F. Kung
Journal of Nuclear Medicine October 2001, 42 (10) 1556-1562;

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    Plasma radioactivity as function of time for first 12 min of scan. Shown with total plasma activity is activity after correction for presence of labeled metabolites.

  • FIGURE 2.
    FIGURE 2.

    Typical set of time–activity curves for uptake of [123I]ADAM in various regions in brain. CER = cerebellum; MB = midbrain.

  • FIGURE 3.
    FIGURE 3.

    Example of graphic analysis of set of time–activity data for midbrain, showing good linearity achieved after t* = 130 min. Axes represent normalized integral of midbrain activity as function of normalized integral of plasma activity.

  • FIGURE 4.
    FIGURE 4.

    Correlation between full kinetic model and 2 simplified models for DVRs of midbrain to cerebellum. For reference tissue model, correlation coefficient R2 = 0.94 (P < 0.001), and regression slope = 0.72 ± 0.07. For ratio method, R2 = 0.89 (P < 0.001), and slope = 0.93 ± 0.12.

  • FIGURE 5.
    FIGURE 5.

    Parametric image (right), at level of midbrain, obtained by calculating DVR at every pixel using reference tissue model compared against coregistered MR image (left) of same animal.

  • FIGURE 6.
    FIGURE 6.

    Determination of optimum time point for measuring ratio of midbrain to cerebellum. Ratios were derived as function of time and compared against full kinetic model result using slope of regression or RMS difference (RMS DIFF) between methods. RMS difference method reaches minimum at roughly same time as slope crosses unity, in range 160–180 min.

Tables

  • TABLE 1

    Kinetic Modeling Parameters Derived from Graphic Analysis of [123I]ADAM Uptake in Brain Combined with Metabolite-Corrected Arterial Plasma Data

    ParameterMB t* (min)DV (mL/mL)
    CERMBTHALSTR
    Mean ± SD138  ±  282.25  ±  0.484.86  ±  1.063.83  ±  0.913.53  ±  0.68
    Test–retest (%)13.114.515.514.7
    Intersubject (%)10.411.513.99.6
    ri0.140.400.00.51

    • MB = midbrain; t

    • ↵* = time after which graphic analysis curve becomes linear; CER = cerebellum; THAL = thalamus; STR = striatum; Test–retest = mean absolute difference between each subject’s mean value and each individual value; Intersubject = between-subject variability, calculated same way as Test–retest; ri = intraclass correlation coefficient.

  • TABLE 2

    Comparison of DVRs Measured with Full Kinetic Modeling Against Reference Tissue Model and Simple Ratio Technique

    ParameterDVRReference regionRatio
    MBTHALSTRMBTHALSTRMBTHALSTR
    Mean ± SD2.16 ± 0.231.70 ± 0.191.58 ± 0.152.01 ± 0.171.63 ± 0.161.53 ± 0.122.23 ± 0.221.83 ± 0.181.68 ± 0.19
    Test–retest (%)7.73.56.35.42.34.67.63.98.2
    Intersubject (%)5.38.86.85.28.15.46.97.19.8
    ri0.320.460.220.030.640.150.090.400.48
    DVR R20.940.970.950.890.980.93
    DVR slope0.72 ± 0.070.86 ± 0.060.79 ± 0.070.93 ± 0.120.97 ± 0.051.23 ± 0.13

    • MB = midbrain; THAL = thalamus; STR = striatum; Test–retest = mean absolute difference between each subject’s mean value and each individual value; Intersubject = between-subject variability, calculated same way as Test–retest; ri = intraclass correlation coefficient; R2 = correlation coefficient of simplified methods against full kinetic model; slope = gradient of regression between simplified methods of analysis and full kinetic model.

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